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Purpose: This study aimed to examine the recovery kinetics (i.e., time-dependent changes) of performance-related variables between two 120-min male football games performed 3 d apart with and without carbohydrate supplementation. Methods: Twenty male players (20 ± 1 yr; body fat, 14.9% ± 5.1%; maximal oxygen consumption, 59.4 ± 3.7 mL⋅kg-1⋅min-1) participated in two 120-min football games (G1, G2) according to a randomized, two-trial, repeated-measures, crossover, double-blind design. Participants received carbohydrate/placebo supplements during recovery between games. Field activity was monitored during the games. Performance testing and blood sampling were performed before and at 90 and 120 min of each game. Muscle biopsies were collected at baseline and at 90 and 120 min of G1 and pre-G2. Results: Compared with G1, G2 was associated with reduced total distance (10,870 vs 10,685 m during 90 min and 3327 vs 3089 m during extra 30 min; P = 0.007-0.038), average (6.7 vs 6.2 km/h during extra 30-min game-play; P = 0.007) and maximal speed (32.2 vs 30.2 km/h during 90 min and 29.0 vs 27.9 km/h during extra 30 min; P < 0.05), accelerations/decelerations (P < 0.05), and mean heart rate (P < 0.05). Repeated sprint ability (P < 0.001), jumping (P < 0.05), and strength (P < 0.001) performance were compromised before and during G2. Muscle glycogen was not restored at G2 baseline (P = 0.005). Extended game-play reduced lymphocyte, erythrocyte counts, hematocrit, hemoglobin, reduced glutathione (P < 0.05) and increased delayed onset of muscle soreness, creatine kinase activity, blood glycerol, ammonia, and protein carbonyls (P < 0.05) before and during G2. Pax7+ (P = 0.004) and MyoD+ cells (P = 0.019) increased at baseline G2. Carbohydrate supplementation restored performance and glycogen, reduced glycerol and delayed onset of muscle soreness responses, and increased leukocyte counts and Pax7+ and MyoD+ cells. Conclusions: Results suggest that extended football games induce a prolonged recovery of performance, which may be facilitated by carbohydrate supplementation during a congested game fixture. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated how extended match time (90 + 30 min) affected physiological responses and fatigue in male soccer players. Methods: Twenty competitive players (mean ± SD: age, 20 ± 1 yr; maximal oxygen uptake, 59 ± 4 mL·min−1·kg−1) completed an experimental match with their activity pattern and heart rate assessed throughout the game, whereas countermovement jump performance and repeated sprint ability were tested and quadriceps muscle biopsies and venous blood samples were taken at baseline and after 90 and 120 min of match play. Results: Less high-intensity running (12%) was performed in extra time in association with fewer intense accelerations and decelerations per minute compared with normal time. Peak sprint speed was 11% lower in extra time compared with normal time, and fatigue also manifested in impaired postmatch repeated sprint ability and countermovement jump performance (all P < 0.05). Muscle glycogen declined from 373 ± 59 mmol·kg−1 dry weight (dw) at baseline to 266 ± 64 mmol·kg−1 dw after 90 min, with a further decline to 186 ± 56 mmol·kg−1 dw after extra time (P < 0.05) and with single-fiber analyses revealing depleted or very low glycogen levels in ~75% of both slow and fast twitch fibers. Blood glucose did not change during the first 90-min but declined (P < 0.05) to 81 ± 8 mg·dL−1 after extra time. Plasma glycerol and ammonia peaked at 236 ± 33 mg·dL−1 and 75 ± 21 μmol·L−1 after the extra period. Conclusions: These findings demonstrate exacerbated fatigue after extra time compared with normal time, which seems to be associated with muscle glycogen depletion, reductions in blood glucose levels, and hyperammonemia. Together, this points to metabolic disturbances being a major part of the integrated and multifaceted fatigue response during extended soccer match play. [ABSTRACT FROM AUTHOR]

Rago, V, Vigh-Larsen, JF, Deylami, K, Muschinsky, A, and Mohr, M. Use of rating of perceived exertion–based training load in elite ice hockey training and match-play. J Strength Cond Res 36(10): 2837–2843, 2022—Training load (TL) based on the subjective rating of perceived exertion (RPE) may be a useful athlete monitoring alternative when wearable technology is unavailable. The aim of this study was to examine the validity of RPE-based TL monitoring in elite ice hockey. A male ice hockey team (n = 18) was monitored using a 200-Hz accelerometer, heart rate (HR) and RPE (0–10 scale), throughout a 4-week competitive period (n = 309 individual observations). Session-RPE (RPE × duration) averaged 244.8 ± 135.2 and 728.6 ± 150.9 arbitrary units (AU) during practice sessions and during official games, respectively. The smallest worthwhile change was 19.8 AU. Within-individual correlations between session-RPE and total accelerations >0.5 m·s−2 (Acctot), accelerations >2 m·s−2 (Acc2), total decelerations >−0.5 m·s−2 (Dectot), decelerations < −2 m·s−2 (Dec2), time > 85% maximum HR, Edwards' TL, and modified training impulse were very large (r = 0.70–0.89; p < 0.001). In addition, correlations between RPE and measures of exercise intensity (Acctot per min, Acc2 per min, Dectot per min, mean HR, and peak HR) were small (r = 0.02–0.29; p < 0.05) except for Dec2 being unclear (p = 0.686). Differences in intensity parameters between RPE range (easy to very hard, 2–7 AU) were small (r = 0.22–0.31; p < 0.05). The session-RPE method can be used as a global indicator of TL in ice hockey. Specific ranges of time-motion and HR intensity variables can be demarcated between RPE categories (easy to very hard; 2–7 AU). Accounting for training volume (session-RPE) more accurately reflects objective methods of TL based on accelerative efforts and HR, than the RPE score (based on the perception of the intensity). [ABSTRACT FROM AUTHOR]

Rago, V, Rebelo, A, Krustrup, P, and Mohr, M. Contextual variables and training load throughout a competitive period in a top-level male soccer team. J Strength Cond Res 35(11): 3177–3183, 2021—The aim of the present study was to investigate and quantify the weekly training load (TL) according to different match-related contextual factors in a professional male soccer team (n = 23). Training load was quantified using a 10-Hz global positioning system with integrated 100-Hz accelerometer and heart rate recordings over a 3-month competitive period. Total distance (TD) covered and high-speed running (HSR, >16 km·h−1) during training were higher in the week after playing against a bottom-level or top-level opponent compared to a medium-level opponent (p < 0.05; effect size [ES] = 0.30–1.04). TD was also higher when preparing for a match against a bottom-level opponent (p < 0.05; ES = 0.39–0.76). In addition, the percentage of HSR was higher after playing a bottom-level compared to a medium-level opponent (p < 0.001; ES = 0.49 [0.27; 0.71]). TD covered was higher in the week following a draw or a win, and higher before a loss compared to a draw (p < 0.05, ES = 0.32–0.81). Both absolute HSR and HSR expressed as percentage of TD were higher before losing and winning a match compared to a draw (p < 0.05; ES = 0.72–0.98). Weekly TL seems to be slightly affected by match-related contextual variables, with special emphasis on the opponent standard and match outcome. Higher training volume was observed before and after playing against a top-level opponent, and after losing a match, whereas the volume of high-intensity training seems to be higher when preparing for a game against a top-level opponent. Future experimental research should clarify the interaction between match-related contextual variables (e.g., cause) and weekly TL (e.g., effect). [ABSTRACT FROM AUTHOR]

Differences in body composition and performance were investigated between elite and U20 male ice hockey players of 2 different national standards. One hundred seventy-nine players were recruited from the highest Finnish (n = 82) and Danish (n = 61) national level, as well as from 1 U20 team from Finland (n = 19) and Denmark (n = 17). Body composition and countermovement jump performance (CMJ) were measured off-ice in addition to on-ice assessments of agility, 10- and 30-m sprint performance, and endurance capacity (the maximal Yo-Yo Intermittent Recovery Level 1 Ice Hockey Test, Yo-Yo IR1-IHmax). Large differences in on-ice performances were demonstrated between Finnish and Danish elite players for agility, 10- and 30-m sprint performance (2-3%, P ≤ 0.05), and Yo-Yo IR1-IHmax performance (15%, P ≤ 0.05). By contrast, no differences (P > 0.05) were present between elite players for CMJ ability or body composition. However, elite players possessed more body and muscle mass than U20 players. Finally, the Finnish U20 cohort had a similar performance level as the Danish elite players and superior 10-m sprint performance, whereas the Danish U20 level was inferior to the other groups in every performance assessment (P ≤ 0.05). In conclusion, on-ice speed and endurance differ markedly between elite players of 2 different national standards with no distinction in body composition or CMJ ability. Moreover, the most consistent difference between U20 and senior elite players was related to body and muscle mass. These results highlight the usefulness of on-ice assessments and suggest the importance of on-ice high-intensity training in elite players in addition to training targeted the development of lean body mass in youth prospects. [ABSTRACT FROM AUTHOR]

The purpose was to evaluate fitness profiles in elite (age 23.5 ± 4.4 years) and subelite (age 19.4 ± 3.1 years) male ice hockey players. Twenty teams from the best (n = 164) and second-best (n = 132) Danish ice hockey division were assessed in-season using a field-test battery consisting of off-ice measurements of countermovement jump (CMJ) performance and body composition, as well as performance tests on the ice. These included the submaximal and maximal Yo-Yo intermittent recovery ice hockey tests, level 1 (Yo-Yo IR1-IHSUB and Yo-Yo IR1-IHMAX), the 5-10-5 pro-agility test, and a straight-line sprint test. Elite players were heavier (85.7 ± 8.1 vs. 80.8 ± 10.0 kg, p ≤ 0.05) and had a higher skeletal muscle mass (41.9 ± 3.9 vs. 38.8 ± 4.7 kg, p ≤ 0.05) than subelite players. Moreover, elite players elicited a superior CMJ (50.1 ± 6.1 vs. 44.9 ± 5.4 cm, p ≤ 0.05), agility (4.76 ± 0.17 vs. 4.96 ± 0.22 seconds, p ≤ 0.05), and sprint (4.49 ± 0.16 vs. 4.71 ± 0.19 seconds, p ≤ 0.05) performance. Finally, elite players outperformed subelite players in Yo-Yo IR1-IHSUB (79.7 ± 6.8 vs. 88.0 ± 5.4% HRmax, p ≤ 0.05) and Yo-Yo IR1-IHMAX tests (2,434 ± 414 vs. 1,850 ± 499 m, p ≤ 0.05). Top elite teams performed. 1.1 and 7% better than bottom elite teams on the agility and CMJ test (p ≤ 0.05), whereas differences approached significance for sprint (p = 0.08) and Yo-Yo IR1-IHMAX (p = 0.08) performance in favor of top-tier teams. No differences were observed between forwards and defensemen. In conclusion, elite-level ice hockey requires a high level of fitness in terms of muscle mass and explosive strength, as well as a well-developed high-intensity intermittent exercise capacity. In addition, these demands seem to apply for both forwards and defensemen. [ABSTRACT FROM AUTHOR]

We examined high-intensity activities in a top-class ice-hockey game and the effect of training status. Male ice-hockey players (n = 36) from the National Hockey League participated. Match analysis was performed during a game and physical capacity was assessed by a sub- maximal Yo-Yo Intermittent Recovery Ice-hockey test, level 1 (YYIR1-IHSUB). Venous blood samples were collected 24-hour post-game to determine markers of muscle damage. Players performed 119 ± 8 and 31 ± 3m⋅min-1 of high intensity and sprint skating, respectively, during a game. Total distance covered was 4,606 ± 219 m (2,260-6,749 m), of which high-intensity distance was 2042 ± 97 m (757-3,026 m). Sprint-skating speed was 5-8% higher (p ≤ 0.05) in periods 1 and 2 vs. period 3 and overtime. Defensemen (D) covered 29% more (p ≤ 0.05) skating in total than forwards (F) and were on the ice 47% longer. However, F performed 54% more (p ≤ 0.05) high-intensity skating per minute than defensemen. Plasma creatine kinase (CK) was 338 ± 45 (78-757) U⋅L-1 24-hour post-game. Heart rate loading during YYIR1-IHSUB correlated inversely (p ≤ 0.05) to the frequency of high-intensity skating bouts (r = 20.55) and ...O2max (r = 20.85) and positively to post-game CK (r =0.49; p ≤ 0.05). In conclusion, ice hockey is a multiple-sprint sport that provokes fatigue in the latter half of a game. Forwards perform more intense skating than defense-men. Moreover, high-intensity game activities during top-class ice hockey are correlated with cardiovascular loading during a submaximal skating test. Taken together, training of elite ice-hockey players should improve the ability for repeated high-intensity skating, and testing should include the YYIR1-IHSUB test as an indicator for ice-hockey-specific physical match performance. [ABSTRACT FROM AUTHOR]

Elite women volleyball players (n = 25; mean ± SD: age, 19 ± 5 years; height, 171 ± 7 cm; weight, 63 ± 1 0 kg) volunteered to participate in the study. They were randomized into a high-intensity training (HIT; n = 13) group and a control (CON; n = 12) group. In addition to the normal team training and games, HIT performed 6-10 x 30-seconds all-out running intervals separated by 3-minute recovery periods 3 times per week during a 4-week in-season period whereas CON only completed the team training sessions and games. Preintervention and postintervention, all players completed the arrowhead agility test (AAT), a repeated sprint test (RST; 5 x 30 meters separated by 25 seconds of recovery), and the Yo-Yo Intermittent Recovery level 2 test (Yo-Yo IR2) followed by a-10 minute rest period and the Yo-Yo IR1 test. Mean running distance during HIT in week 1 was 152 ± 4 m and increased (p ≤ 0.05) by 4.6% (1 59 ± 3 m) in week 4. The AAT performance improved (p ≤ 0.05) by 2.3% (1 8.87 ± 0.97-1 8.44 ± 1.06 seconds) and RST by 4.3% postintervention in the HIT group only. Baseline RST fatigue index was 7.0 ± 2.9 and 6.2 ± 5.0% in HIT and CON, respectively, but was lowered (p ≤ 0.05) to 2.7 ± 3.0% posttraining in HIT and remained unaltered in CON (5.5 ± 5.0%). In HIT, Yo-Yo IR2 and Yo-Yo IR1 performance improved by 1 2.6 and 1 8.3% postintervention, respectively, with greater (p ≤ 0.05) Yo-yo IR1 change scores than in CON. In conclusion, additional high-intensity in-season training performed as interval running improved agility, repeated sprint ability, and high-intensity intermittent exercise performance in elite women volleyball players. [ABSTRACT FROM AUTHOR]

Background: Although regular exercise is recommended for preventing and treating overweight/obesity, the most effective exercise type for improving cardiometabolic health in individuals with overweight/obesity remains largely undecided. This network meta-analysis aimed to evaluate and rank the comparative efficacy of 5 exercise modalities on cardiometabolic health measures in individuals with overweight/obesity.Methods: A database search was conducted in MEDLINE, Embase, Scopus, and Web of Science from inception up to September 2020. The review focused on randomized controlled trials involving exercise interventions consisting of continuous endurance training, interval training, resistance training, combined aerobic and resistance training (combined training), and hybrid-type training. Exercise interventions aimed to improve somatometric variables, body composition, lipid metabolism, glucose control, blood pressure, cardiorespiratory fitness, and muscular strength. The Cochrane risk of bias tool was used to evaluate eligible studies. A random-effects network meta-analysis was performed within a frequentist framework. The intervention ranking was carried out using a Bayesian model where mean and SD were equal to the respective frequentist estimates.Results: A total of 4331 participants (59% female; mean age: 38.7±12.3 years) from 81 studies were included. Combined training was the most effective modality and hybrid-type training the second most effective in improving cardiometabolic health-related outcomes in these populations suggesting a higher efficacy for multicomponent exercise interventions compared to single-component modalities, that is, continuous endurance training, interval training, and resistance training. A subgroup analysis revealed that the effects from different exercise types were mediated by gender.Conclusions: These findings corroborate the latest guidelines on exercise for individuals with overweight/obesity highlighting the importance of a multicomponent exercise approach to improve cardiometabolic health. Physicians and healthcare professionals should consider prescribing multicomponent exercise interventions to adults with overweight/obesity to maximize clinical outcomes.Registration: URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42020202647. [ABSTRACT FROM AUTHOR]

The article reports on research conducted to compare movement pattern, fatigue development, and heart rate for top class elite female players when playing international versus domestic league games. Researchers evaluated 17 players. They found that the elite female soccer players performed more high intensity running when playing in international games than in domestic league games and that there was no difference in heart rate between the two types of games.

The article reports on research conducted to examine the fatigue pattern of elite female soccer players after competitive games. Researchers evaluated 23 players from the Danish women Premier League. They found that the type of fatigue that occurs after a female soccer game caused marked impairment in intense intermittent exercise and repeated sprint performance but did not affect vertical jump performance.

The article presents the study conducted regarding the match performance and physical demands of the elite women soccer players. The study, administered to top-class and high-level players, will examine the effect of their changing locomotor activities on their performance. It shows that the greater the standard of the players the greater their running intensity becomes.

The article cites a study on the physiological response, reliability and validity of Yo-Yo intermittent recovery level two test (Yo-Yo IR2) in soccer players. Thirteen males carried four Yo-Yo IR2 tests, an incremental treadmill test and various sprint tests. Subjects' muscle biopsies, blood samples and heart rate were measured before, during and after the tests. One-hundred ninety-nine Scandinavian elite soccer players carried out Yo-Yo IR2 test in two or four occasions. The study analyzed that Yo-Yo IR2 test was reproducible and evaluates athletes' ability to perform aerobic or anaerobic exercises. It is concluded that Yo-Yo IR2 test is sensitive tool to differentiate intermittent exercise performance of soccer players.

The article examines muscle and blood metabolites during soccer match play, which are then related to possible changes in sprint performance. The study used 31 Danish fourth division players, who took part in three friendly soccer games. Blood samples were frequently collected from the test subjects during the game, and muscle biopsies were taken before and after the game as well as immediately after each half or after an intense exercise period in each half. Muscle lactate and blood lactate levels were measured during the first and second halves of the soccer games.

PURPOSE: To examine hydration, wellness status and physical loading during a National team training camp in football. METHODS: Thirty-one male players (age; 27±4 yrs., height; 185±6 cm, weight; 82.9±6.7 kg; body-fat content; 10.4±2.3%) representing a UEFA National team participated in the study. The players were investigated during three different National team training camps in the fall of 2020 in relation to the UEFA National League tournament. Urine specific gravity (USG) was measured during all tree camps in order to assess hydrational status. The players were actively coached during all camps on improving hydration strategies and were given individual feedback on their test results. Training load was measured with GPS technology and wellness questionnaires were completed. RESULTS: Baseline USC on the first camp day was 1.025±0.005 g·ml -1 with nearly 90% of the players being significantly dehydrated and none of them being well hydrated. During camp-1, 2 and 3 mean USG was 1.019±0.003, 1.018±0.002 and 1.018±0.004 g·ml-1, respectively, being lower (P<0.05) compared to baseline. Mean USG on day -2 and match-day during camp-1, 2 and 3 demonstrated that 42, 17 and 33%, respectively, of the players were dehydrated during the three camps. When data from the three camps were pooled together USG was 1.021±0.003 g·ml-1 on day -2 and decreased (P<0.05) to 1.016±0.002 g·ml-1 on match-day. On average 52% of the players were dehydrated on only day -2 and 6% on match-day. Hydrational status improved progressively during the three camps with fewer dehydrated players and more well hydrated players during the last part of camp-3 compared to the first part of camp-1. No correlations were observed between hydrational status and training load or wellness markers. CONCLUSION: dehydration appears to be a challenge in elite male football, but continuous monitoring of hydrations status and coaching hydration strategies causes great improvement and reduced the degree of dehydration. [ABSTRACT FROM AUTHOR]

Purpose: To examine the activity profile and physical loading of elite female soccer players during match play and to study the relationship between training status and physical match performance., Methods: Time-motion analysis and HR recordings were performed on 14 elite female soccer players during competitive matches. In addition, the players carried out a laboratory treadmill test and the Yo-Yo intermittent recovery test., Results: The total distance covered during a game was 10.3 km (range: 9.7-11.3) with high-intensity running (HIR) accounting for 1.31 km (0.71-1.70). HIR was performed 125 times (72-159) for 2.3 s (2.0-2.4) on average. The average and peak HR in a game were 167 beats per minute (bpm) (152-186) and 186 (171-205), respectively, corresponding to 87% (81-93) and 97% (96-100) of HR(max). Maximal pulmonary oxygen uptake (VO2max) was 49.4 mL.min(-1).kg(-1) (43.4-56.8), and incremental treadmill test (ITT) performance was 4.49 min (3.38-5.17). The Yo-Yo test performance was 1379 m (600-1960). The total distance covered during match play did not correlate with VO2max or ITT performance but correlated with the Yo-Yo test result (r = 0.56, P < 0.05). Significant positive correlations were observed between HIR and VO2max (r = 0.81, P < 0.05), ITT (r = 0.82, P < 0.05), and Yo-Yo test performance (r = 0.76, P < 0.05). No relationship was observed between HR(max) during match play and any of the performance measures., Conclusion: The present study demonstrated that 1) HIR during games varies markedly between elite female soccer players, 2) all players have high HR throughout a competitive game with periods of near-maximal values, 3) the distance covered by HIR during match play is closely related to the physical capacity, and 4) the Yo-Yo intermittent recovery test can be used as an indicator of the physical match performance of elite female players.

Purpose: We tested the hypotheses that previous glycogen depletion of slow-twitch (ST) fibers enhances recruitment of fast-twitch (FT) fibers, elevates energy requirement, and results in a slow component of VO2 during moderate-intensity dynamic exercise in humans., Methods: Twelve healthy, male subjects cycled for 20 min at approximately 50% VO2max with normal glycogen stores (CON) and with exercise-induced glycogen depleted ST fibers (CHO-DEP). Pulmonary VO2 was measured continuously and single fiber, muscle homogenate, and blood metabolites were determined repeatedly during each trial., Results: ST fiber glycogen content decreased (P < 0.05) during CON (293 +/- 24 to 204 +/- 17 mmol x kg d.w.), but not during CHO-DEP (92 +/- 22 and 84 +/- 13 mmol x kg d.w.). FT fiber CP and glycogen levels were unaltered during CON, whereas FT fiber CP levels decreased (29 +/- 7%, P < 0.05) during CHO-DEP and glycogen content tended to decrease (32 +/- 14%, P = 0.07). During CHO-DEP, VO2 was higher (P < 0.05) from 2 to 20 min than in CON (0-20 min:7 +/- 1%). Muscle lactate, pH and temperature, ventilation, and plasma epinephrine were not different between trials. From 3 to 20 min of CHO-DEP, VO2 increased (P <0.05) by 5 +/- 1% from 1.95 +/- 0.05 to 2.06 +/- 0.08 L x min but was unchanged during CON. In this exercise period, muscle pH and blood lactate were unaltered in both trials. Exponential modeling revealed a slow component of VO2 equivalent to 0.12 +/- 0.04 L x min during CHO-DEP., Conclusion: This study demonstrates that previous glycogen depletion of ST fibers enhances FT fiber recruitment, elevates O2 cost, and causes a slow component of VO2 during dynamic exercise with no blood lactate accumulation or muscular acidosis. These findings suggest that FT fiber recruitment elevates energy requirement of dynamic exercise in humans and support an important role of active FT fibers in producing the slow component of VO2

Purpose: To examine the physiological response and reproducibility of the Yo-Yo intermittent recovery test and its application to elite soccer., Methods: Heart rate was measured, and metabolites were determined in blood and muscle biopsies obtained before, during, and after the Yo-Yo test in 17 males. Physiological measurements were also performed during a Yo-Yo retest and an exhaustive incremental treadmill test (ITT). Additionally, 37 male elite soccer players performed two to four seasonal tests, and the results were related to physical performance in matches., Results: The test-retest CV for the Yo-Yo test was 4.9%. Peak heart rate was similar in ITT and Yo-Yo test (189 +/- 2 vs 187 +/- 2 bpm), whereas peak blood lactate was higher (P < 0.05) in the Yo-Yo test. During the Yo-Yo test, muscle lactate increased eightfold (P < 0.05) and muscle creatine phosphate (CP) and glycogen decreased (P < 0.05) by 51% and 23%, respectively. No significant differences were observed in muscle CP, lactate, pH, or glycogen between 90 and 100% of exhaustion time. During the precompetition period, elite soccer players improved (P < 0.05) Yo-Yo test performance and maximum oxygen uptake ([OV0312]O(2max)) by 25 +/- 6 and 7 +/- 1%, respectively. High-intensity running covered by the players during games was correlated to Yo-Yo test performance (r = 0.71, P < 0.05) but not to [OV0312]O(2max) and ITT performance., Conclusion: The test had a high reproducibility and sensitivity, allowing for detailed analysis of the physical capacity of athletes in intermittent sports. Specifically, the Yo-Yo intermittent recovery test was a valid measure of fitness performance in soccer. During the test, the aerobic loading approached maximal values, and the anaerobic energy system was highly taxed. Additionally, the study suggests that fatigue during intense intermittent short-term exercise was unrelated to muscle CP, lactate, pH, and glycogen.