Matthew Ronald Spencer

• Bugten, Jesper Barth; Solstad, Bård Erlend; Ivarsson, Andreas; Spencer, Matthew; Stenling, Andreas & Haugen, Tommy (2026). Youth Sport Players' Enjoyment in Team Practice Sessions: The Daily Impact of Coaches and Basic Psychological Need Satisfaction. Journal of Sport & Exercise Psychology (JSEP). ISSN 0895-2779. 48(5), s. 315–323. doi: 10.1123/jsep.2025-0306. Fulltekst i vitenarkiv
• O'Brien, Brendan J; Worn, Ryan; Clark, Brad & Spencer, Matthew (2025). Reliability and criterion validity of the Concept 2 SkiErg™ to assess 1000-m on-snow, time trial performance – a case study. Frontiers in Sports and Active Living. 7. doi: 10.3389/fspor.2025.1631229. Fulltekst i vitenarkiv Vis sammendrag

  Objectives: This study investigated the reliability and criterion validity of the Concept 2 SkiErg™ to assess 1000-m on-snow, time trial performance using the classical double poling technique. Methods: Ten athletes (5 males and females) from a National cross-country ski team participated in the study and completed a 1000-m time trial on snow, as well as two 1000-m time trials on the Concept 2 SkiErg™ in a temperature-controlled room during a 4-day training camp. Results: There was a significant decrease in time from test 1 to test 2 of 4.87 s (238.3 ± 26.1 v 233.4 ± 23.9 s; 95% limits of agreement [LoA]: -5.5, 15.3). The Concept 2 SkiErg™ time-trial had a coefficient of variation (CV) of 1.6% and the standard error of measurement was 3.8 s. When compared to the on-snow time-trial, the Concept 2 SkiErg™ time-trial demonstrated a mean bias of 20.7 s (95% LoA; 11.6, 29.8) and the concordance correlation coefficient was 0.72. Conclusion: The Concept 2 SkiErg™ demonstrated excellent single-trial reliability. However, there was significant proportional bias in the Concept 2 SkiErg™ relative to the on-snow test and agreement between the two was relatively poor. Research using a larger sample and different trial durations is required to further validate the Concept 2 SkiErg™ for cross-country skiing performance testing.

• Bugten, Jesper Barth; Haugen, Tommy; Ivarsson, Andreas; Knight, Camilla J.; Ommundsen, Yngvar & Spencer, Matthew [Vis alle 8 forfattere av denne artikkelen] (2025). Daily measures of sport enjoyment, social interaction, and attendance among female adolescent handball players. Psychology of Sport And Exercise. ISSN 1469-0292. 79. doi: 10.1016/j.psychsport.2025.102852. Fulltekst i vitenarkiv Vis sammendrag

  This study investigates how sport enjoyment and the immediate impact of social interactions with peers and coaches influence short-term sport participation among early adolescent female handball players. By using a diary study approach, data from 27 players over 10 practices in 4 weeks (270 measurement points) were collected. The findings revealed that coach controlling use of rewards during practice increased the risk of non-attendance at the subsequent practices, while peer relatedness support after practice increased attendance probability. Contrarily, peer intra-team conflict, coach negative conditional regard, and sport enjoyment did not predict attendance, suggesting that peer relatedness support and coach controlling use of rewards are more influential in short-term participation decisions for this group of players. Sport enjoyment during practice, as well as peer relatedness support during and after practice, predicted sport enjoyment the following practice. These results highlight the importance of feedback timing and interaction quality in youth sports. Further exploration is proposed on these dynamics across a wider range of demographics, and longer time periods to understand the impact of short- and long-term sport participation.

• Byrkjedal, Per Thomas; Bjørnsen, Thomas; Luteberget, Live Steinnes; Ivarsson, Andreas & Spencer, Matthew (2024). Assessing the individual relationships between physical test improvements and external load match parameters in male professional football players—a brief report. Frontiers in Sports and Active Living. 6. doi: 10.3389/fspor.2024.1367894. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: This study aimed to explore whether a meaningful improvement in physical performance following an in-season strength training intervention can be related to external load match parameters at an individual level in professional male football players. Methods: Eight male professional football players (25.4 ± 3.1 years, 184.1 ± 3.4 cm, 79.3 ± 2.2 kg) completed a 10-week strength intervention period in addition to football-specific training and matches. Commonly used physical and external load measures were assessed before and after intervention. Physical performance improvements had to exceed the measurement’s typical error and the smallest worthwhile difference (SWD) to be considered meaningful. External load match parameters were assessed before and after the intervention period using SWD and non-overlap of all pairs (NAP) analysis. A Bayesian pairwise correlation analysis was performed to evaluate relationships between changes in physical performance and external load match parameters. Results: Three players displayed meaningful improvements in two to five physical performance measures. However, positive changes exceeding the SWD and positive effects in NAP results were observed for all players in external load match parameters. Kendall's tau correlation analysis showed evidence (base factor >3) for only one correlation (maximum speed − decelerations, τ = −0.62) between the changes in physical performance and external load measures, while the remaining comparisons exhibited no relation. Conclusions: The findings suggest that improvements in physical performance may not necessarily translate to improvements in external load match parameters. Further research, with larger sample sizes, is needed to understand potential mechanisms between acute and chronic physical performance changes and football external load parameters during training and matches.

• Mooney, Mitchell; Worn, Ryan; Spencer, Matthew & O’Brien, Brendan J. (2024). Anaerobic and Aerobic Metabolic Capacities Contributing to Yo-Yo Intermittent Recovery Level 2 Test Performance in Australian Rules Footballers. Sports. 12(9). doi: 10.3390/sports12090236. Fulltekst i vitenarkiv
• Byrkjedal, Per Thomas; Thunshelle, Atle; Spencer, Matthew; Luteberget, Live Steinnes; Ivarsson, Andreas & Vårvik, Fredrik Tonstad [Vis alle 8 forfattere av denne artikkelen] (2023). In-season autoregulation of one weekly strength training session maintains physical and external load match performance in professional male football players. Journal of Sports Sciences. ISSN 0264-0414. 41(6), s. 536–546. doi: 10.1080/02640414.2023.2227536. Fulltekst i vitenarkiv Vis sammendrag

  The aim of this study was to compare the effects of autoregulating strength training volume based on an objective (external load match performance) versus a subjective (self-selected) method in professional male football players. Sixteen players completed a 10-week strength training programme where the number of sets was regulated based on football match high-intensity running distance (HIR >19.8 km/h, AUTO, n = 7), or self-selected (SELF, n = 9). In addition to traditional physical performance assessments (30-m sprint, countermovement jump, leg-strength, and body composition), external load match performance was assessed with five matches in the beginning and in the end of the study period. Both groups performed ~ 1 weekly bout of ~ 6 sets in leg extensor exercises during the 10-week period, and maintained physical performance during the competitive season, with no group differences detected after the training period. Non-overlap of all pairs (NAP) analysis showed weak-to-moderate effects in external load match performance from before to after the study period, suggesting that players maintained or improved their performance. In conclusion, no group differences were observed, suggesting that both external load autoregulated and self-selected, low-volume in-season strength training maintained physical, and external load match performance in professional male football players.

• Byrkjedal, Per Thomas; Bjørnsen, Thomas; Luteberget, Live; Lindberg, Kolbjørn Andreas; Ivarsson, Andreas & Haukali, Eirik [Vis alle 7 forfattere av denne artikkelen] (2023). Association Between Physical Performance Tests and External Load During Scrimmages in Highly Trained Youth Ice Hockey Players. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 18(1), s. 47–54. doi: 10.1123/ijspp.2022-0225. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: To investigate the relationship between physical performance tests and on-ice external load from simulated games (scrimmages) in ice hockey. Methods: A total of 14 players completed a physical performance test battery consisting of 30-m sprint test—run and 30-m sprint test—skate (including 10-m split times and maximum speed), countermovement jump, standing long jump, bench press, pull-ups, and trap bar deadlift and participated in 4 scrimmages. External load variables from scrimmages included total distance; peak speed; slow (< 11.0 km/h), moderate (11.0–16.9 km/h), high (17.0–23.9 km/h), and sprint (> 24.0 km/h) speed skating distance; number of sprints; PlayerLoad™; number of high-intensity events (> 2.5 m/s); accelerations; decelerations; and changes of direction. Bayesian pairwise correlation analyses were performed to assess the relationship between physical performance tests and external load performance variables. Results: The results showed strong evidence (Bayes factor > 10) for associations between pull-ups and high-intensity events (τ = .61) and between maximum speed skate and peak speed (τ = .55). There was moderate evidence (Bayes factor >3 to <10) for 6 associations: both maximum speed skate (τ = .44) and countermovement jump (τ = .44) with sprint speed skating distance, countermovement jump with number of sprints (τ = .46), pull-ups with changes of direction (τ = .50), trap bar with peak speed (τ = .45), and body mass with total distance (τ = .49). Conclusion: This study found physical performance tests to be associated with some of the external load variables from scrimmages. Nevertheless, the majority of correlations did not display meaningful associations, possibly being influenced by the selection of physical performance tests.

• Byrkjedal, Per Thomas; Luteberget, Live; Bjørnsen, Thomas; Ivarsson, Andreas & Spencer, Matthew (2022). Simulated Game-Based Ice Hockey Match Design (Scrimmage) Elicits Greater Intensity in External Load Parameters Compared With Official Matches. Frontiers in Sports and Active Living. 4. doi: 10.3389/fspor.2022.822127. Fulltekst i vitenarkiv Vis sammendrag

  Objective: A limited number of studies have explored the external load experienced in indoor sports such as ice hockey, and few the link between training and match performance. As a paucity exists within this topic, this study explored whether a simulated match design (i.e., scrimmage) could be representative of official match demands and elicit similar external loads as in official matches in a group of elite youth male ice hockey players. Methods: A total of 26 players were monitored during eight official and four simulation matches using a Local Positioning System. Total distance, max velocity, slow (0–10.9 km/h), moderate (11–16.9 km/h), high (17.0–23.9 km/h), and sprint (>24 km/h) speed skating distance, distance per min, PlayerLoadTM, PlayerLoadTM per min, high-intensity events (HIEs) (>2.5 m/s−2), acceleration (ACCs), decelerations (DECs), and change of directions (CODs) were extracted from the tracking devices. A two-level regression analysis was conducted to compare the difference between match types when controlling for time on ice, match day, and position. Results: Between match-type results showed a credible difference in all variables except max velocity and ACCs. Distance per min was 27.3% higher during simulation matches and was explained by a 21.3, 24.1, and 14.8% higher distance in sprint-, high-, and moderate speed skating distance, while slow speed-skating distance was 49.2% lower and total distance only trivially different from official to simulation matches. Total PlayerLoadTM was 11.2% lower, while PlayerLoadTM per min was 8.5% higher during simulation matches. HIEs, CODs, and DECs were 10.0, 11.9, and 22.3% higher during simulation matches. Conclusion: The simulated match design is related to official match demands with comparable match-time, playing time, number of shifts, and shift duration. However, simulation matches provoked a higher external load output compared with official matches, possibly explained by a more continuous movement design. A game-based simulation match design can therefore be utilized when match-related actions at high intensity are warranted.

• Wiig, Håvard; Cumming, Kristoffer Toldnes; Handegard, Vilde; Hansen, Jostein Stabell; Spencer, Matthew & Raastad, Truls (2022). Muscular heat shock protein response and muscle damage after semi-professional football match. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 32(6), s. 984–996. doi: 10.1111/sms.14148. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: A typical football match leads to neuromuscular fatigue and physical performance impairments up to 72–96 h post-match. While muscle damage is thought to be a major factor, damage on the ultrastructural level has never been documented. The purpose of this study was to investigate post-match cellular muscle damage by quantifying the heat shock protein (HSP) response as a proxy for protein damage. Methods: Muscle biopsies, blood samples, countermovement jumps, and perception of muscle soreness were obtained from twelve semi-professional football players 1, 24, 48, and 72 h after a 90-min football match. Muscle biopsies were analyzed for αB-crystallin and HSP70 in the cytosolic and cytoskeletal sub-cellular fractions by Western blotting. Fiber type-specific αB-crystallin and HSP70 staining intensity, and tenascin-C immunoreactivity were analyzed with immunohistochemistry. Blood samples were analyzed for creatine kinase and myoglobin. Results: Within 24 h post-match, a 2.7- and 9.9-fold increase in creatine kinase and myoglobin were observed, countermovement jump performance decreased by −9.7% and muscle soreness increased by 0.68 units. αB-crystallin and HSP70 accumulated in cytoskeletal structures evident by a 3.6- and 1.8-fold increase in the cytoskeletal fraction and a parallel decrease in the cytosolic fraction. In type I and II fibers, αB-crystallin staining intensity increased by 15%–41% and remained elevated at 72 h post-match. Lastly, the percentage of fibers with granular staining of αB-crystallin increased 2.2-fold. Conclusions: Football match play induced a muscular HSP stress response 1–72 h post-match. Specifically, the accumulation of HSPs in cytoskeletal structures and the granular staining of αB-crystallin suggests occurrence of ultrastructural damage. The damage, indicated by the HSP response, might be one reason for the typically 72 h decrease in force-generating capacity after football matches.

• Taylor, Madison; Almquist, Nicki Winfield; Rønnestad, Bent; Tjønna, Arnt Erik; Kristoffersen, Morten & Spencer, Matthew [Vis alle 8 forfattere av denne artikkelen] (2021). The inclusion of sprints in low-intensity sessions during the transition period of elite cyclists improves endurance performance 6 weeks into the subsequent preparatory period. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 16(10), s. 1502–1509. doi: 10.1123/IJSPP.2020-0594. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: To investigate the effects of including repeated sprints in a weekly low-intensity (LIT) session during a 3-week transition period on cycling performance 6 weeks into the subsequent preparatory period (PREP) in elite cyclists. Methods: Eleven elite male cyclists (age = 22.0 [3.8] y, body mass = 73.0 [5.8] kg, height = 186 [7] cm, maximal oxygen uptake [VO2max] = 5469 [384] mL·min−1) reduced their training load by 64% and performed only LIT sessions (CON, n = 6) or included 3 sets of 3 × 30-second maximal sprints in a weekly LIT session (SPR, n = 5) during a 3-week transition period. There was no difference in the reduction in training load during the transition period between groups. Physiological and performance measures were compared between the end of the competitive period and 6 weeks into the PREP. Results: SPR demonstrated a 7.3% (7.2%) improvement in mean power output during a 20-minute all-out test at PREP, which was greater than CON (−1.3% [4.6%]) (P = .048). SPR had a corresponding 7.0% (3.6%) improvement in average VO2 during the 20-minute all-out test, which was larger than the 0.7% (6.0%) change in CON (P = .042). No change in VO2max, gross efficiency, or power output at blood lactate concentration of 4 mmol·L−1 from competitive period to PREP occurred in either group. Conclusion: Including sprints in a weekly LIT session during the transition period of elite cyclists provided a performance advantage 6 weeks into the subsequent PREP, which coincided with a higher performance VO2.

• McGawley, Kerry; Spencer, Matthew; Olofsson, Anna & Andersson, Erik (2021). Comparing active, passive, and combined warm-ups among junior alpine skiers in -7°C. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 16(8), s. 1140–1147. doi: 10.1123/IJSPP.2020-0300. Fulltekst i vitenarkiv Vis sammendrag

  Context: Warming up in very cold climates and maintaining an elevated body temperature prior to a race is challenging for snow-sport athletes. Purpose: To investigate the effects of active (ACT), passive (PAS), and a combination of ACT and PAS (COM) warm-ups on maximal physical performance in a subzero environment among snow-sport athletes. Methods: Ten junior alpine skiers completed 3 experimental trials in −7.2 (0.2)°C. The ACT involved 5 minutes of moderate cycling, 3 × 15-second accelerations, a 6-second sprint, 5 countermovement jumps (CMJs), and a 10-minute passive transition phase, while in PAS, participants wore a lower-body heated garment for 24 minutes. In COM, participants completed the active warm-up, then wore the heated garment during the transition phase. Two maximal CMJs and a 90-second maximal isokinetic cycling test followed the warm-up. Results: CMJ performance was likely (P =.150) and very likely (P =.013) greater in ACT and COM, respectively, versus PAS. Average power output during the cycling test was likely (P =.074) greater in ACT and COM versus PAS. Participants felt likely to almost certainly warmer (P <.01) and more comfortable (P =.161) during ACT and COM versus PAS. In addition, participants felt likely warmer (P =.136) and very likely more comfortable (P =.161) in COM versus ACT. Conclusions: COM resulted in significantly improved CMJ performance versus PAS while both ACT and COM led to likely improved 90-second cycling performance. Participants felt significantly warmer during ACT and COM versus PAS and likely warmer in COM versus ACT. Therefore, a combined warm-up is recommended for alpine skiers performing in subzero temperatures.

• Almquist, Nicki Winfield; Løvlien, Ine; Byrkjedal, Per Thomas; Spencer, Matthew; Kristoffersen, Morten & Skovereng, Knut [Vis alle 8 forfattere av denne artikkelen] (2020). Effects of Including Sprints in One Weekly Low-Intensity Training Session During the Transition Period of Elite Cyclists. Frontiers in Physiology. 11(1000). doi: 10.3389/fphys.2020.01000. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of this study was to investigate the effects of including 30-s sprints in one weekly low-intensity training (LIT) session during a 3-week transition period in elite cyclists. Sixteen male elite cyclists (maximal oxygen uptake, VO2max: 72 ± 5 ml·kg−1·min−1) reduced their training load by ~60% for 3 weeks from the end of competitive season and performed only LIT or included 30-s sprints (SPR) in one weekly LIT-session. Performance and physiological capacities were evaluated during a prolonged (~2.5 h) test-session, including a strength test, a submaximal blood lactate profile test, an incremental test to exhaustion to determine VO2max, 1 h continuous cycling including four maximal 30-s sprints, and a 20-min all-out test. In addition, mental recovery was evaluated using the Athlete Burnout Questionnaire (ARQ). The only significant between-group change during the transition period was an 8 ± 11% larger improvement in 30-s sprint performance in SPR compared to control (CON; SPR: 4 ± 5%, CON: −4 ± 5%, p = 0.01). Although not different from CON, SPR maintained 20-min all-out performance (−1 ± 5%, p = 0.37) and fractional utilization of VO2max (1.9 ± 6.1%-points, p = 0.18) during the 20-min all-out test, whereas corresponding declines were observed in CON (−3 ± 5%, p = 0.04, and −2.5 ± 2.9%-points, p = 0.02, respectively). Power output at 4 mmol·L−1 blood lactate concentration decreased similarly in SPR (−4 ± 4%, p = 0.02) and CON (−5 ± 5%, p = 0.01), while VO2max, maximal aerobic power (Wmax), and total burnout score were unaffected in both groups. Including sprints in one weekly LIT-session in the transition period improves sprint performance and maintains 20-min all-out power and fractional utilization of VO2max without compromising mental recovery. Inclusion of sprints in LIT-sessions may therefore be a plausible, time-efficient strategy during short periods of reduced training.

• Wiig, Håvard; Andersen, Thor Einar; Luteberget, Live & Spencer, Matthew (2020). Individual Response to External Training Load in Elite Football Players. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 15(5), s. 696–704. doi: 10.1123/ijspp.2019-0453. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: To investigate within-player effect, between-player effect, and individual response of external training load from player tracking devices on session rating of perceived exertion training load (sRPE-TL) in elite football players. Methods: The authors collected sRPE-TL from 18 outfield players in 21 training sessions. Total distance, high-speed running distance (>14.4 m/s), very high-speed running distance (>19.8 m/s), PlayerLoad™, PlayerLoad2D™, and high-intensity events (HIE > 1.5, HIE > 2.5, and HIE > 3.5 m/s) were extracted from the tracking devices. The authors modeled within-player and between-player effects of single external load variables on sRPE-TL, and multiple levels of variability, using a linear mixed model. The effect of 2 SDs of external load on sRPE-TL was evaluated with magnitude-based inferences. Results: Total distance, PlayerLoad™, PlayerLoad2D™, and HIE > 1.5 had most likely substantial within-player effects on sRPE-TL (100%–106%, very large effect sizes). Moreover, the authors observed likely substantial between-player effects (12%–19%, small to moderate effect sizes) from the majority of the external load variables and likely to very likely substantial individual responses of PlayerLoad™, high-speed running distance, very high-speed running distance, and HIE > 1.5 (19%–30% coefficient of variation, moderate to large effect sizes). Finally, sRPE-TL showed large to very large between-session variability with all external load variables. Conclusions: External load variables with low intensity-thresholds had the strongest relationship with sRPE-TL. Furthermore, the between-player effect of external load and the individual response to external load advocate for monitoring sRPE-TL in addition to external load. Finally, the large between-session variability in sRPE-TL demonstrates that substantial amounts of sRPE-TL in training sessions are not explained by single external load variables.

• Wiig, Håvard; Raastad, Truls; Luteberget, Live; Ims, Ingvar & Spencer, Matthew (2019). External load variables affect recovery markers up to 72 h after semiprofessional football matches. Frontiers in Physiology. 10. doi: 10.3389/fphys.2019.00689. Fulltekst i vitenarkiv Vis sammendrag

  Background: Player tracking devices are commonly used to monitor external load from training and matches in team sports. Yet, how the derived external load variables relate to fatigue and recovery post-training or post-match is scarcely researched. The objective was, therefore, to investigate how external load variables affect recovery markers up to 72 h post-match. Methods: Semiprofessional players from six teams wore tracking devices during three experimental football matches. External load variables including individual playing duration, total distance, PlayerLoad™, high-intensity running, and high-intensity events were derived from the tracking devices, and blood samples and performance tests from 24–59 players were undertaken post-match. The effect of the external load variables on creatine kinase, myoglobin, and countermovement jump at 1, 24, 48, and 72 h, and 30-m sprint and Yo-Yo intermittent recovery tests level 1 at 72 h post-match, were modeled. Effects were gauged as two standard deviations of the external load and interpreted as the difference between a typical high-load and a typical low-load match. The effects were evaluated with 90% confidence intervals and magnitude-based inferences. Results: High-intensity running had very likely substantial effects on creatine kinase and myoglobin (moderate factor increases of 1.5–2.0 and 1.3–1.6 respectively), while duration, total distance, and HIE showed small, likely substantial effects. PlayerLoad™ and total distance had likely substantial effects on 30-m sprint time (small increases of 2.1–2.6%). Effects on countermovement jump performance were generally non-substantial. Despite these relationships, the uncertainty was too large to predict the recovery of individual players from the external load variables. Conclusions: This study provides evidence that external load variables have an effect on recovery markers up to 72 h post-match. Hence, tracking external load in matches may be helpful for practitioners when managing training load and recovery strategies post-match. However, it is recommended that several different external load variables are monitored. Future research should continue to address the problem of predicting recovery from external load variables.

• Gamble, Declan; Spencer, Matthew; Mccarren, Andrew & Moyna, Niall (2019). Activity profile, PlayerLoad™ and heart rate response of Gaelic football players: A pilot study. Journal of Human Sport and Exercise. 14(4), s. 711–724. doi: 10.14198/jhse.2019.144.01. Fulltekst i vitenarkiv Vis sammendrag

  The objectives of this study were to; quantify positional differences in the activity profiles of Gaelic football players and to evaluate decrements in physical performance during a pre-season competition. Global positioning system (GPS) data was recorded from 36 players from 3 teams across 5 games. The relative distance covered in locomotor activities, peak speed, relative PlayerLoad™ (PL.min-1 ) and heart rate responses were evaluated between playing positions and across match periods using a mixed model analysis. The mean relative distance of 92.4 ± 23.3 m.min-1 covered, comprised 28.4 ± 10.2 m.min-1 of high intensity running (m.min-1 ≥ 4.0 m.s-1 ) and 9.9 ± 3.9 m.min-1 of very high intensity running (m.min-1 ≥ 5.5 m.s-1 ). High intensity running and relative PlayerLoad™ (PL.min-1 ) was significantly higher in half-backs, midfielders and half-forwards compared to the full-backs, whereas only the half-backs and half-forwards displayed significantly greater values compared to full-forwards. When compared to the first 15 min (P1) of the game, analysis of pooled positional data revealed significant declines in; overall relative distance covered, jogging (≥2.0 - < 4.0 m.s-1 ), running (≥4.0 - <5.5 m.s-1 ), high intensity running and PL.min-1 ,in P2 (20-35 min) and P4 (55-70 min). Significant reductions in average heart rate were also found between the first and second halves and between P1 with both P3 and P4. These results highlight differences in the physical performance requirements of specific positions and provide evidence of reductions in work-rate during games. Coaches can use this information to inform the development of both team and position-specific conditioning programmes.

• Luteberget, Live; Spencer, Matthew & Gilgien, Matthias (2018). Validity of the Catapult ClearSky T6 local positioning system for team sports specific drills, in indoor conditions. Frontiers in Physiology. 9. doi: 10.3389/fphys.2018.00115. Fulltekst i vitenarkiv Vis sammendrag

  Aim: The aim of the present study was to determine the validity of position, distance traveled and instantaneous speed of team sport players as measured by a commercially available local positioning system (LPS) during indoor use. In addition, the study investigated how the placement of the field of play relative to the anchor nodes and walls of the building affected the validity of the system. Method: The LPS (Catapult ClearSky T6, Catapult Sports, Australia) and the reference system [Qualisys Oqus, Qualisys AB, Sweden, (infra-red camera system)] were installed around the field of play to capture the athletes' motion. Athletes completed five tasks, all designed to imitate team-sports movements. The same protocol was completed in two sessions, one with an assumed optimal geometrical setup of the LPS (optimal condition), and once with a sub-optimal geometrical setup of the LPS (sub-optimal condition). Raw two-dimensional position data were extracted from both the LPS and the reference system for accuracy assessment. Position, distance and speed were compared. Results: The mean difference between the LPS and reference system for all position estimations was 0.21 ± 0.13 m (n = 30,166) in the optimal setup, and 1.79 ± 7.61 m (n = 22,799) in the sub-optimal setup. The average difference in distance was below 2% for all tasks in the optimal condition, while it was below 30% in the sub-optimal condition. Instantaneous speed showed the largest differences between the LPS and reference system of all variables, both in the optimal (≥35%) and sub-optimal condition (≥74%). The differences between the LPS and reference system in instantaneous speed were speed dependent, showing increased differences with increasing speed. Discussion: Measures of position, distance, and average speed from the LPS show low errors, and can be used confidently in time-motion analyses for indoor team sports. The calculation of instantaneous speed from LPS raw data is not valid. To enhance instantaneous speed calculation the application of appropriate filtering techniques to enhance the validity of such data should be investigated. For all measures, the placement of anchor nodes and the field of play relative to the walls of the building influence LPS output to a large degree.

• Luteberget, Live; Holme, Benjamin R. & Spencer, Matthew (2018). Reliability of Wearable Inertial Measurement Units to Measure Physical Activity in Team Handball. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 13(4), s. 467–473. doi: 10.1123/ijspp.2017-0036. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: The purpose of this study was to assess the reliability and sensitivity of commercially available inertial measurement units (IMU) to measure physical activity in team handball. Method: Twenty-two handball players were instrumented with two IMUs (OptimEye S5, Catapult Sports, Australia) taped together. They participated in either a laboratory assessment (n=10), consisting of seven team handball specific tasks, or field assessment (n=12) conducted in twelve training sessions. Variables, including PlayerLoad™ and inertial movement analysis (IMA) magnitude and counts, were extracted from the manufactures software. IMA count was divided into intensity bands of low (1.5-2.5m·s-1), medium (2.5-3.5m·s-1), high (>3.5m·s-1), medium/high (>2.5m·s-1), and total (>1.5m·s-1). Reliability between devices and sensitivity was established using coefficient of variation (CV) and smallest worthwhile difference (SWD). Results: Laboratory assessment : IMA magnitude showed a good reliability (CV: 3.1%) in well-controlled tasks. CV increased (4.4-6.7%) in more complex tasks. Field assessment : Total IMA count (CV: 1.8%, SWD: 2.5%), PlayerLoad™ (CV: 0.9 % SWD: 2.1%), and its associated variables (CV: 0.4-1.7%) showed a good reliability, well below the SWD. However, the CV of IMA increased when categorized into intensity bands (2.9-5.6%). Conclusion: The reliability of IMA count were good, when data was displayed as total, high or medium/high counts. A good reliability for PlayerLoad™ and associated variables was evident. The CV of the aforementioned variables was well below the SWD, suggesting that OptimEye IMU and its software are sensitive for use in team handball.

• Luteberget, Live; Trollerud, Hege Pernille & Spencer, Matthew (2018). Physical demands of game-based training drills in women’s team handball. Journal of Sports Sciences. ISSN 0264-0414. 36(5), s. 592–598. doi: 10.1080/02640414.2017.1325964. Fulltekst i vitenarkiv Vis sammendrag

  Game-based training drills are popular in team sports. This study compared two game-based training conditions and official matches in team handball. Thirty-one women players wore inertial measurement units in five training sessions and five official matches. In training, 3vs3 and 6vs6 game-based training conditions were performed with a 5-min duration. PlayerLoad™ and high-intensity events (HIEs; >2.5 m · s−1) were extracted from the raw data. Data were analysed using magnitude-based inferences and reported with effect sizes (ESs). PlayerLoad™ · min−1 from all positions combined was 11.37 ± 0.49 (mean ± 90% confidence limits) and 9.71 ± 0.3 for the 3vs3 and 6vs6 conditions, respectively. Backs (ES: 1.63), wings (ES: 1.91), and pivots (ES: 1.58) had greater PlayerLoad™ in 3vs3 than 6vs6. Substantially greater HIE · min−1 in 3vs3 occurred for all positions. There was substantially greater PlayerLoad™ · min−1 in 3vs3 and 6vs6 than match play for backs, wings, and pivots. Wings (ES: 1.95), pivots (ES: 0.70), and goalkeeper (ES: 1.13) had substantially greater HIE · min−1 in 3vs3 than match play. This study shows greater PlayerLoad™ and HIE in 3vs3 than 6vs6. Both game-based training conditions investigated in this study provide an overload in overall PlayerLoad™; however, additional exercises might be needed to overload HIE, especially for backs and pivots.

• Luteberget, Live & Spencer, Matthew (2017). High-intensity events in international women's team handball matches. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 12(1), s. 56–61. doi: 10.1123/ijspp.2015-0641. Fulltekst i vitenarkiv Vis sammendrag

  International female team handball is a physically demanding sport and is intermittent in nature. The aim of the study was to profile high intensity events (HIE) in international female team handball matches, with regards to playing positions. Methods: Twenty female national team handball players were equipped with inertial movement units (OptimEye S5, Catapult Sports, Australia) in 9 official international matches. Players were categorized in four different playing positions: backs, wings, pivots, and goalkeepers (GK). Player Load™, accelerations (Acc), changes of direction (CoD), decelerations (Dec), and the sum of the latter three, HIE, were extracted from data raw-files, using the manufacture’s software. All Acc, Dec, CoD, and HIE >2.5 m·s-1 were included. Data were log-transformed and differences were standardized for interpretation of magnitudes and reported with effect size (ES) statistic. Results: Mean number of events was 0.7 ± 0.4 Acc·min-1, 2.3 ± 0.9 Dec·min-1, and 1.0 ± 0.4 CoD·min-1. Substantial differences between playing positions, ranging from small to very large, were found in the three parameters. Backs showed a most likely greater frequency for HIE·min-1 (5.0 ± 1.1 HIE·min-1), than all other playing positions. Differences between playing positions was also apparent in Player Load·min-1. Conclusion: The present study shows that HIE in international female team handball are position specific, and that the overall intensity is dependent on the positional role within a team. Specific HIE and intensity profiles from match play provide useful information for a better understanding of the overall game demands and for each playing position.

• Wik, Eirik Halvorsen; Luteberget, Live & Spencer, Matthew (2017). Activity Profiles in International Female Team Handball Using PlayerLoad™. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 12(7), s. 934–942. doi: 10.1123/ijspp.2015-0732. Fulltekst i vitenarkiv Vis sammendrag

  Team handball matches place diverse physical demands on players, which may result in fatigue and decreased activity levels. However, previous speed-based methods of quantifying player activity may not be sensitive for capturing short-lasting team handball-specific movements. Purpose: To examine activity profiles of a female team handball team and individual player profiles, using inertial measurement units (IMUs). Methods: Match data was obtained from one female national team in nine international matches (n=85 individual player samples), using the Catapult OptimEye S5. PlayerLoad™􀂘min-1 was used as a measure of intensity in 5- and 10-minute periods. Team profiles were presented as relative to the player’s match means, and individual profiles were presented as relative to the mean of the 5- minute periods with >60% field time. Results: A high initial intensity was observed for team profiles, and for players with ≥2 consecutive periods of play. Substantial declines in PlayerLoad™􀂘min-1 were observed throughout matches for the team, and for players with several consecutive periods of field time. These trends were found for all positional categories. Intensity increased substantially in the final five minutes of the first half for team profiles. Activity levels were substantially lower in the five minutes after a player’s most intense period, and were partly restored in the subsequent 5-minute period. Discussion: Possible explanations for the observed declines in activity profiles for the team and individual players include fatiguing players, situational factors and pacing. However, underlying mechanisms were not accounted for, and these assumptions are therefore based on previous team-sport studies.

• Rønnestad, Bent; Hansen, Joar; Hollan, Ivana; Spencer, Matthew & Ellefsen, Stian (2015). In-Season Strength Training Cessation Impairs Performance Variables in Elite Cyclists. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. doi: 10.1123/ijspp.2015-0372. Fulltekst i vitenarkiv Vis sammendrag

  The present study investigates the effects of 8 weeks of strength training cessation following 25 weeks of strength training on strength- and cycling performance characteristics. Elite cyclists were randomly assigned to either 25 weeks of endurance training combined with heavy strength training [EXP, n=7, maximal oxygen uptake (VO2max): 77±6 ml·kg-1·min-1 (3x4-10 RM, 1-2 day·week-1)] or to endurance training only [CON, n=7, VO2max: 73±5 ml·kg-1·min-1]. Thereafter, both groups performed endurance training only for 8 weeks, coinciding with the initial part of the competition season. Data were assessed for practical significance using magnitude-based inferences. During the 25-week preparatory period, EXP had a larger positive impact on maximal isometric half squat force, squat jump (SJ), maximal aerobic power (Wmax), power output at 4 mmol∙L-1 [la-], and mean power in 30-s Wingate test compared to CON (ES=0.46-0.74). Conversely, during the 8-week competition period EXP had a reduction in SJ, Wmax, and mean power in the 30-s Wingate test compared to CON (ES=0.49-0.84). The present findings suggest rapid decline of adaptations upon termination of strength training during the 8 first weeks of the competition period in elite cyclists.

• Luteberget, Live; Raastad, Truls; Seynnes, Olivier R. & Spencer, Matthew (2015). Effect of Traditional and Resisted Sprint Training in Highly-Trained, Female Team Handball Players. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 10(5), s. 642–647. doi: 10.1123/ijspp.2014-0276. Fulltekst i vitenarkiv Vis sammendrag

  Fast acceleration is an important performance factor in handball. In addition to traditional sprint training (TST), resisted sprint training (RST) is a method often used to improve acceleration. However, studies on RST show conflicting results, and underlying mechanisms are not studied. Purpose: To compare the effects of RST, by sled towing, against traditional sprint training on sprint performance and muscle architecture. Methods: Participants (n=18) were assigned to either RST or TST and completed two training sessions of RST or TST per week (10 weeks), in addition to their normal team training. Sprint-tests (10-m and 30-m) and measurements of muscle architecture were performed pre- and post-training. Results: Beneficial effects were found in the 30-m sprint test (mean; ±90% CL) for both groups (TST=-0.31; ±0.19 s, RST=-0.16; ±0.13 s), with unclear differences between the groups. Only TST had a beneficial effect on 10-m time (-0.04; ±0.04 s), with a likely difference between the two groups (85 %, ES= 0.60). Both groups had a decrease in pennation angle (-6.0; ±3.3% for TST and -2.8; ±2.0% for RST), which had a nearly perfect correlation with percentage change in 10-m sprint performance (r=0.92). A small increase in fascicle length (5.3; ±3.9% and 4.0; ±2.1% for TST and RST, respectively) was found, with unclear differences between groups. Discussion: TST appears to be more effective than RST in enhancing 10-m sprint time. Both groups showed similar effects in 30-m sprint time. A similar, yet small, effect of sprint training on muscle architecture was observed in both groups.

• Sandbakk, Øyvind; Skålvik, Tommy Fredriksen; Spencer, Matthew; Beekvelt, Mireille Van; Welde, Boye & Hegge, Ann Magdalen [Vis alle 8 forfattere av denne artikkelen] (2015). The physiological responses to repeated upper-body sprint exercise in highly trained athletes. European Journal of Applied Physiology. ISSN 1439-6319. 115(6), s. 1381–1391. doi: 10.1007/s00421-015-3128-6. Fulltekst i vitenarkiv
• Losnegard, Thomas; Andersen, Martin; Spencer, Matthew & Hallén, Jostein (2015). Effects of active versus passive recovery in sprint cross-country skiing. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 10(5), s. 630–635. doi: 10.1123/ijspp.2014-0218. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: To investigate the effects of an active and a passive recovery protocol on physiological responses and performance between 2 heats in sprint cross-country skiing. Methods: Ten elite male skiers (22 ± 3 y, 184 ± 4 cm, 79 ± 7 kg) undertook 2 experimental test sessions that both consisted of 2 heats with 25 min between start of the first and second heats. The heats were conducted as an 800-m time trial (6°, >3.5 m/s, ~205 s) and included measurements of oxygen uptake (VO2) and accumulated oxygen deficit. The active recovery trial involved 2 min standing/walking, 16 min jogging (58% ± 5% of VO2peak), and 3 min standing/walking. The passive recovery trial involved 15 min sitting, 3 min walk/jog (~ 30% of VO2peak), and 3 min standing/walking. Blood lactate concentration and heart rate were monitored throughout the recovery periods. Results: The increased 800-m time between heat 1 and heat 2 was trivial after active recovery (effect size [ES] = 0.1, P = .64) and small after passive recovery (ES = 0.4, P = .14). The 1.2% ± 2.1% (mean ± 90% CL) difference between protocols was not significant (ES = 0.3, P = .3). In heat 2, peak and average VO2 was increased after the active recovery protocol. Conclusions: Neither passive recovery nor running at ~58% of VO2peak between 2 heats changed performance significantly.

• Stadheim, Hans Kristian; Nossum, Eirik Myhr; Olsen, Raymond; Spencer, Matthew & Jensen, Jørgen (2015). Caffeine improves performance in double poling during acute exposure to 2,000-m altitude. Journal of applied physiology. ISSN 8750-7587. 119(12), s. 1501–1509. doi: 10.1152/japplphysiol.00509.2015. Fulltekst i vitenarkiv Vis sammendrag

  There is limited research on the physiological effects of caffeine (CAF) ingestion on exercise performance during acute hypoxia. The aim of the present study was therefore to test the effect of placebo (PLA) and CAF (4.5 mg/kg) on double poling (DP) performance during acute hypoxia. Thirteen male subelite cross-country skiers (V̇o2max 72.6 ± 5.68 ml·kg−1·min−1) were included. Performance was assessed as 1) an 8-km cross-country DP time-trial (C-PT), and 2) time until task failure at a set workload equal to ∼90% of DP V̇o2max. Testing was carried out in a hypobaric chamber, at 800 mbar (Pio2: ∼125 mmHg) corresponding to ∼2,000 m above sea level in a randomized double-blinded, placebo-controlled, cross-over design. CAF improved time to task failure from 6.10 ± 1.40 to 7.22 ± 1.30 min (P < 0.05) and velocity the first 4 km (P < 0.05) but not overall time usage for the 8-km C-PT. During submaximal exercise subjects reported lower pain in arms and rate of perceived exertion (RPE) following CAF ingestion. Throughout C-PTs similar RPE and pain was shown between treatments. However, higher heart rate was observed during the CAF 8 km (187 ± 7 vs. 185 ± 7; P < 0.05) and 90% C-PT (185 ± 7 vs. 181 ± 9) associated with increased ventilation, blood lactate, glucose, adrenaline, decreased pH, and bicarbonate. The present study demonstrates for the first time that CAF ingestion improves DP time to task failure although not consistently time trial performance during acute exposure to altitude. Mechanisms underpinning improvements seem related to reduced pain RPE and increased heart rate during CAF C-PTs.

• Hermassi, Souhail; Gabbett, Tim J.; Spencer, Matthew; Khalifa, Riadh; Chelly, Mohamed Souhaiel & Chamari, Karim (2014). Relationship between Explosive Performance Measurements of the Lower Limb and Repeated Shuttle-Sprint ability in Elite Adolescent Handball Players. International journal of sports science & coaching. ISSN 1747-9541. 9(5), s. 1191–1204. doi: 10.1260/1747-9541.9.5.1191. Fulltekst i vitenarkiv Vis sammendrag

  This study investigated the relationship between performance measures of the lower-limb and repeated shuttle-sprint ability (RSSA) in elite adolescent handball players. Twenty-two male handball players (age: 17.7 ± 0.3 years) participated in the study. Subjects underwent measurements of lower-limb maximal strength (1-RM half back squat), explosive power (force-velocity test), jumping ability (squat and counter-movement jumps), sprinting velocities over the first step (VS) and the first 5 m (V5) of a 15 m sprint, and Yo-Yo Intermittent Recovery Test, Level 1. The players were tested for RSSA using a protocol of 6 repetitions of maximal 2 x 15-m shuttle sprints with 180° turns (~6 s) departing every 20 s. RSSA results were evaluated in three ways: best time in a single trial (RSSAbest), decrement (RSSAdec) and total time (RSSATT). The correlations of RSSA with the assorted fitness measures varied considerably. The RSSATT and RSSAdec were positively associated with 1-RM half back squat (r = 0.78 and r = 0.68 respectively; p< 0.01). Significant correlations were also found between RSSATT and RSSAbest and absolute peak power of the lower limb (r = -0.81 and -0.66, respectively; p<0.01). There was a moderate correlation between first step sprinting velocities and RSSATT (r= -0.71; p< 0.01). The RSSA test score has a moderate to large association with other explosive power measurements in elite adolescent handball players. RSSA may provide a useful composite index on responses to training or rehabilitation, and is very suitable for monitoring athletic performance of the lower-limbs of elite adolescent handball players.

• Pyne, David Bruce; Spencer, Matthew & Mujika, Iñigo (2014). Improving the value of fitness testing for football. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 9(3), s. 511–514. doi: 10.1123/IJSPP.2013-0453. Fulltekst i vitenarkiv Vis sammendrag

  One of the challenges for sports scientists working in football is to balance the needs for routine fitness testing with daily fatigue and well-being monitoring to best manage the physical preparation of players. In this com - mentary, the authors examine contemporary issues of fitness testing in football to identify ways of improving the value of routine testing and monitoring. A testing program must be well planned and organized to ensure that the results are useful. Different tests can be employed for younger and older players. A rigorous approach to analysis and interpretation of results is desirable, and database management must address both short- and long-term requirements of players, staff, and programs.

• Sandbakk, Øyvind; Spencer, Matthew; Ettema, Gerardus Johannes C; Bucher, Silvana Andrea; Skovereng, Knut & Welde, Boye (2014). The Physiology and Biomechanics of Upper-Body Repeated Sprints in Ice Sledge Hockey. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 9(1), s. 77–84. doi: 10.1123/IJSPP.2012-0355. Fulltekst i vitenarkiv Vis sammendrag

  PURPOSE: To investigate performance and the associated physiological and biomechanical responses during upper-body repeated sprint work. METHODS: Twelve male ice sledge hockey players from the Norwegian national team performed eight 30-m sprints with start every 30 s and an active recovery between sprints. Time was captured every 10 m by photocells, cycle length and rate were determined by video analyses, and heart rate and blood lactate concentration were measured by conventional methods. RESULTS: The percent sprint decrement was 7% over the eight trials, with significant reductions in performances from the previous trial already on the second trial (all P<0.05). Furthermore, cycle rate was reduced by 9% over the eight trials (P<0.05). Similar changes in performance and kinematic patterns were evident for all 10-m phases of the sprints. Heart rate gradually increased to 94% of maximal (178±10 beats/min) over the eight trials, and the mean reductions in heart rate was 7±2 beats/min during the 22-24 s of active recovery for all trials (all P<0.05). The blood lactate concentration increased to the athletes' maximal levels over the eight sprints (P<0.05). CONCLUSIONS: This is the first study to investigate performance, physiological and biomechanical aspects of self propulsed upper-body repeated sprint work. The observed sprint decrement over the eight trials was associated with reductions in cycle rates and high physiological demands. However, no kinematic and physiological characteristics were significantly correlated to repeated sprint ability or the sprint decrement.

• Spencer, Matthew; Losnegard, Thomas; Hallén, Jostein & Hopkins, Will (2014). Variability and Predictability of Performance Times of Elite Cross-Country Skiers. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 9(1), s. 5–11. doi: 10.1123/IJSPP.2012-0382. Fulltekst i vitenarkiv Vis sammendrag

  Analyses of elite competitive performance provide useful information for research and practical applications. Purpose: Here the authors analyze performance times of cross-country skiers at international competitions (World Cup, World Championship, and Olympics) in classical and free styles of women’s and men’s distance and sprint events, each with a total of 410–569 athletes competing in 1–44 races at 15–25 venues from seasons 2002 to 2011. Methods: A linear mixed model of race times for each event provided estimates of within-athlete race-to-race variability expressed as a coefficient of variation (CV) after adjustment for fixed or random effects of snow conditions, altitude, race length, and competition terrain. Results: Within-athlete variability was similar for men and women over various events for all athletes (CV of 1.5–1.8%) and for the annual top-10 athletes (1.1–1.4%). Observed effects of snow conditions and altitude on mean time were substantial (~2%) but mostly unclear, owing to large effects of terrain (CV of 4–10% in top-10 analyses). Predictability of performance was extremely high for all athletes (intraclass correlations of .90–.96) but only trivial to poor for top-10 athletes (men .00–.03, women .03–.35). Conclusion: The race-to-race variability of top-ranked skiers is similar to that of other elite endurance athletes. Estimates of the smallest worthwhile performance enhancement (0.3× within-athlete variability) will help researchers and practitioners evaluate strategies affecting performance of elite skiers.

• Stadheim, Hans Kristian; Spencer, Matthew; Olsen, Raymond & Jensen, Jørgen (2014). Caffeine and performance over consecutive days of simulated competition. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 46(9), s. 1787–1796. doi: 10.1249/MSS.0000000000000288. Fulltekst i vitenarkiv Vis sammendrag

  Caffeine and Performance over Consecutive Days of Simulated Competition. Med. Sci. Sports Exerc., Vol. 46, No. 9, pp. 1787–1796, 2014. Purpose: Performance improvements after caffeine (CAF) ingestion are well documented when using a 1-d protocol. In numerous competitions such as the Tour de France, Tour de Ski, world championships, and National College Athletic Association championships, athletes compete for several days in a row. To date, no studies have investigated the effects of CAF when competing for consecutive days in a row. This study aimed to investigate the effects of placebo (PLA) and two different CAF doses (3 and 4.5 mgIkgj1 body mass) on performance in a 10-min all-out, cross-country, double poling ergometer test (C-PT) 2 d in a row. Method: Eight highly trained male cross-country skiers (V˙ O2max-run, 78.5 T 1.6 mLIkgj1 Iminj1 ) participated in the study, which was a randomized, double-blind, PLA-controlled, crossover design. Performance was assessed as distance covered during a 10-min all-out C-PT. Oral ingestion of CAF or PLA was consumed 75 min before the all-out C-PT. Results: Poling distance was improved after CAF ingestions compared with that after PLA on both days. The improvements on day 1 were 4.0% (90% confidence limits, T3.3) and 4.0% T 2.9% for both CAF doses, respectively (P G 0.05), whereas improvements on day 2 were 5.0% T 3.6% and 5.1% T 2.8% for CAF3 and CAF4.5, respectively, compared with those for PLA. Improved performance was associated with increased HR, adrenaline concentration, blood lactate concentration, and V˙ O2 consumption after CAF ingestion. Furthermore, performance was elevated despite higher creatine kinase concentration and muscular pain at arrival on day 2 for both CAF doses. Conclusions: Both CAF doses improved performance in the 10-min all-out C-PT compared with PLA over two consecutive days. Therefore, CAF seems useful for athletes competing over consecutive days despite higher muscle damage occurring after enhanced performance on the first day.

• Gabbett, Tim J.; Wiig, Håvard & Spencer, Matthew (2013). Repeated High-Intensity Running and Sprinting in Elite Women's Soccer Competition. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 8(2), s. 130–138. doi: 10.1123/ijspp.8.2.130. Fulltekst i vitenarkiv Vis sammendrag

  Background: To the authors’ knowledge, no study has investigated the concurrent repeated, high-intensity (RHIA) and repeated-sprint activity (RSA) of intermittent team-sport competition. Purpose: In this study, they report on the RSA of elite women’s football competition. In addition, they describe the nature of RHIA (eg, striding and sprinting activities) that involve a high energy cost and are associated with short (ie, ≤20 s) recovery periods. Methods: Thirteen elite women soccer players underwent video-based time–motion analysis on 34 occasions during national and international standard matches. RSA and RHIA were defined as successive (ie, 2) sprints or striding and sprinting efforts that occurred with ≤20 s between efforts. Results: The number of RSA and RHIA bouts performed was similar between the first and second halves of matches. Sprinting and striding/sprinting durations tended to remain relatively stable irrespective of the number of efforts in an RSA or RHIA bout or the period of play. However, recovery duration between efforts increased in the second half, when a greater number of efforts were performed per bout. Conclusion: These findings suggest that first- to second-half reductions in RHIA and RSA do not occur in elite women’s soccer competition. However, players increase the amount of low-intensity recovery undertaken between RHIA and RSA efforts, most likely in an attempt to maintain RHIA and RSA performance. These findings emphasize the importance of RSA and RHIA to elite women’s soccer and highlight the importance of training this quality to prevent reductions in performance during competitive match play.

• Ettema, Gertja; Skålvik, Tommy; Spencer, Matthew & Sandbakk, Øyvind (2013). Performance and coordination in repeated sprint exercise for the upper body. I Balagué, N.; Torrents, C.; Villanova, A.; Cadefau, J.; Tarragó, R. & Tsolakidis, E. (Red.), Book of Abstracts.18th annual Congress of the European College of Sport Science. 26th - 29th June, Barcelona - Spain. European College of Sport Science. ISSN 9788469577868. Fulltekst i vitenarkiv
• Losnegard, Thomas; Myklebust, Håvard; Spencer, Matthew & Hallén, Jostein (2013). Seasonal Variations in V.o(2)max, O-2-Cost, O-2-Deficit, and Performance in Elite Cross-Country Skiers. Journal of Strength and Conditioning Research. ISSN 1064-8011. 27(7), s. 1780–1790. doi: 10.1519/JSC.0b013e31827368f6. Fulltekst i vitenarkiv Vis sammendrag

  Long-term effects of training are important information for athletes, coaches, and scientists when associating changes in physiological indices with changes in performance. Therefore, this study monitored changes in aerobic and anaerobic capacities and performance in a group of elite cross-country skiers during a full sport season. Thirteen men (age, 23 ± 2 years; height, 182 ± 6 cm; body mass, 76 ± 8 kg; V2 roller ski skating VO2max, 79.3 ± 4.4 ml·kg·min or 6.0 ± 0.5 L·min) were tested during the early, middle, and late preparation phase: June (T1), August (T2), and October (T3); during the competition phase: January/February (T4); and after early precompetition phase: June (T5). O2-cost during submaximal efforts, V[Combining Dot Above]O2peak, accumulated oxygen deficit (ΣO2-deficit), and performance during a 1,000-m test were determined in the V2 ski skating technique on a roller ski treadmill. Subjects performed their training on an individual basis, and detailed training logs were categorized into different intensity zones and exercise modes. Total training volume was highest during the summer months (early preseason) and decreased toward and through the winter season, whereas the volume of high-intensity training increased (all p < 0.05). There was a significant main effect among testing sessions for 1,000 m time, O2-cost, and ΣO2-deficit (Cohen's d effect size; ES = 0.63-1.37, moderate to large, all p < 0.05). In general, the changes occurred between T1 and T3 with minor changes in the competitive season (T3 to T4). No significant changes were found in V[Combining Dot Above]O2peak across the year (ES = 0.17, trivial). In conclusion, the training performed by elite cross-country skiers induced no significant changes in V[Combining Dot Above]O2peak but improved performance, O2-cost, and ΣO2-deficit.

• Spencer, Matthew; Pyne, David; Santisteban, Juanma & Mujika, Iñigo (2011). Fitness Determinants of Repeated-Sprint Ability in Highly Trained Youth Football Players. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 6(4), s. 497–508. doi: 10.1123/ijspp.6.4.497. Fulltekst i vitenarkiv Vis sammendrag

  Variations in rates of growth and development in young football players can influence relationships among various fitness qualities. Purpose: To investigate the relationships between repeated-sprint ability and other fundamental fitness qualities of acceleration, agility, explosive leg power, and aerobic conditioning through the age groups of U11 to U18 in highly trained junior football players. Methods: Male players (n = 119) across the age groups completed a fitness assessment battery over two testing sessions. The first session consisted of countermovement jumps without and with arm swing, 15-m sprint run, 15-m agility run, and the 20-m Shuttle Run (U11 to U15) or the Yo-Yo Intermittent Recovery Test, Level 1 (U16 to U18). The players were tested for repeated-sprint ability in the second testing session using a protocol of 6 × 30-m sprints on 30 s with an active recovery. Results: The correlations of repeated-sprint ability with the assorted fitness tests varied considerably between the age groups, especially for agility (r = .02 to .92) and explosive leg power (r = .04 to .84). Correlations of repeated sprint ability with acceleration (r = .48 to .93) and aerobic conditioning (r = .28 to .68) were less variable with age. Conclusion: Repeated-sprint ability associates differently with other fundamental fitness tests throughout the teenage years in highly trained football players, although stabilization of these relationships occurs by the age of 18 y. Coaches in junior football should prescribe physical training accounting for variations in short-term disruptions or impairment of physical performance during this developmental period.

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• Spencer, Matthew; Byrkjedal, Per Thomas; Luteberget, Live Steinnes; Ivarsson, Andreas & Bjørnsen, Thomas (2023). Assessing the individual relationship between physical fitness improvements and external load match performance in male professional football players – a case study. Fulltekst i vitenarkiv
• Byrkjedal, Per Thomas; Thunshelle, Atle; Spencer, Matthew; Luteberget, Live Steinnes; Ivarsson, Andreas & Vårvik, Fredrik Tonstad [Vis alle 8 forfattere av denne artikkelen] (2023). In-season autoregulation of one weekly strength training session maintains physical performance in professional male football players. Fulltekst i vitenarkiv
• Byrkjedal, Per Thomas; Bjørnsen, Thomas; Luteberget, Live Steinnes; Lindberg, Kolbjørn Andreas; Ivarsson, Andreas & Haukali, Eirik [Vis alle 7 forfattere av denne artikkelen] (2022). Relationship between external load from simulated ice-hockey games and physical test performance. Fulltekst i vitenarkiv
• Spencer, Matthew (2022). Hvordan best varme opp i OL-kulda? lokalavisen fedrelandsvennen. Fulltekst i vitenarkiv
• Spencer, Matthew (2022). Measuring training load in team sports: opportunities, challenges, and practical applications. Fulltekst i vitenarkiv
• Spencer, Matthew & Wiig, Håvard (2022). Within player monitoring of wellness, sleep and readiness to play and the effect of training load in elite football. Fulltekst i vitenarkiv
• Byrkjedal, Per Thomas; Stenqvist, Thomas Birkedal; Torstveit, Monica Klungland; Bergsvik, Kristina & Spencer, Matthew (2020). No effect of a three-week post-season transition period on markers of RED-S in highly-trained male cyclists. Fulltekst i vitenarkiv
• Spencer, Matthew (2020). Fysiske krav i fotball med bruk av teknologi. Fulltekst i vitenarkiv
• Spencer, Matthew; Wiig, Håvard; Andersen, Thor Einar & Luteberget, Live (2020). INDIVIDUAL RESPONSE TO EXTERNAL TRAINING LOAD IN ELITE FOOTBALL PLAYERS. Fulltekst i vitenarkiv
• Coward, Espen; Spencer, Matthew & Stenqvist, Thomas Birkedal (2020). TRAINING METHODS AND INTENSITY DISTRIBUTION OF YOUNG ELITE ENDURANCE ATHLETES: A TWO-YEAR LONGITUDI- NAL STUDY. Fulltekst i vitenarkiv
• Wiig, Håvard; Raastad, Truls; Andersen, Thor Einar & Spencer, Matthew (2015). Monitoring Sleep, Well-Being and Training Load During a Season in Norwegian Professional Football. Fulltekst i vitenarkiv
• Vagle, Markus & Spencer, Matthew (2014). The effect of maximal resistance training vs. combined resistance/plyometric training on strength and sprint performance in elite women's football. Fulltekst i vitenarkiv
• Rønnestad, Bent; Hansen, Joar; Ellefsen, Stian & Spencer, Matthew (2014). Use it or lose it: In-season strength training cessation impairs performance variables in elite cyclists. Fulltekst i vitenarkiv
• Ettema, Gertja; Skålvik, Tommy; Spencer, Matthew & Sandbakk, Øyvind (2013). Performance and coordination in repeated sprint exercise for the upper body. Fulltekst i vitenarkiv

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