Yo-Yo Intermittent Recovery Test Performance Research Articles

A repeated shuttle sprint test with female and male international field hockey players is reliable and associated with single sprint but not intermittent endurance performance.

Field hockey is a high-intensity intermittent team sport that has recently undergone a series of rule changes that have resulted in a greater demand for repeated high-intensity movements. Coaches and practitioners now require a reliable assessment of repeated accelerations, decelerations and changes of direction to assess these important match qualities. This investigation assessed the test-retest reliability of a novel 6x40m repeated shuttle sprint test (20m + 20m with a 180° turn) and its association with 40m straight line sprint and YoYo Intermittent Recovery Test performance in 28 International field hockey players (n = 14 females and n = 14 males). The sum of 6 sprint times (SUM) demonstrated ‘excellent’ (ICC = 0.94 and CV = 0.59%) and ‘good’ (ICC = 0.84 and CV = 0.75%) reliability in females and males, respectively. Best sprint time during the repeated shuttle sprint test also demonstrated suitable reliability to evaluate field hockey physical performance (ICC = 0.92 & 0.76, CV = 0.76% & 1.00% in females and males, respectively). SUM was significantly associated with 40 m straight line sprint performance in females (r = 0.90; p<0.001) and males (r = 0.92; p<0.001), but only a weak association was found with YoYo Intermittent Recovery Test performance for either group (r = 0.20; p = 0.495 & r = -0.19; p = 0.525 in females and males, respectively). In summary, field hockey testing batteries that include a repeated shuttle sprint test should consider including a test of intermittent endurance. Further, changes in SUM greater than 1.0% can be confidently interpreted by coaches and practitioners as a real change for both female and male elite field hockey players.

Detrimental Effects of the Off-Season in Soccer Players: A Systematic Review and Meta-analysis.

The off-season period in soccer leads necessarily to changes in fitness status. However, there is a lack of systematization that allows identifying the magnitude of these changes in groups participating in off-season training programs compared with those subjected to training cessation. This systematic review with meta-analysis was conducted to assess the effects of training cessation in off-season training programs on men soccer players' body fat, maximal oxygen uptake (VO2max), yo-yo intermittent recovery test (YYIRT), vertical jump, sprinting time, and repeated-sprint ability. To qualify for inclusion in the systematic review, studies must have included: (1) a detraining period of ≥ 2weeks; (2) controlled trials or cohorts of healthy men soccer players with no restriction on age; and (3) a pre-post training cessation or off-season training programs measure of body fat (%), VO2max (mLkg-1min-1), YYIRT performance (meters), vertical jump (height), sprinting (time), and repeated-sprint ability (total time). The electronic search yielded 563 articles, and 12 were subsequently included. Significant (all p < 0.05) detrimental training cessation effects were noted for body fat (ES = 0.26), VO2max (ES = - 1.48), YYIRT (ES = - 0.46), vertical jump (ES = - 0.81), and repeated-sprint ability (ES = 0.68). Similarly, significant (all p < 0.05) detrimental off-season training programs effects were noted for body fat (ES = 0.26), VO2max (ES = - 0.48), vertical jump (ES = - 0.51), and sprinting time (ES = 0.86). When training cessation and off-season training programs effects were compared, greater detrimental effects were noted after training cessation for VO2max (p = 0.002) and repeated-sprint ability (p < 0.001). Detrimental effects on body composition and physical fitness were observed after both training cessation and off-season training programs. However, off-season training programs seem to ameliorate such detrimental effects on VO2max and repeated-sprint ability to some extent. The results presented here call for the implementation of more effective off-season training programs among male soccer players.

The examination of Yo-Yo intermittent recovery test performance of young soccer players at different playing positions

Background and Study Aim. The aerobic fitness in soccer is an important performance component. The aerobic endurance level of players may positively effect performance of critical match activities. The examination of Yo-Yo intermittent recovery test (YYIRT) performance of young soccer players at different playing positions was aimed in this study.&#x0D; Material and Methods. The research group was consisted of 75 young soccer players playing at U-21 category of professional soccer teams at different leagues. The soccer players at 5 different playing positions participated in study voluntarily (centerback: n=15, fullback: midfielder: n=15, winger: n=15, forward: n=15). The YYIRT (level 1) was performed for determination aerobic endurance parameters (covered distance during test, maximum oxygen uptake (VO2max) and maximal aerobic speed (MAS) of players. The one-way ANOVA analysis was used for comparison between playing positions of YYIRT parameters.&#x0D; Results. It was determined that difference between YYIRT parameters of players at different playing positions was non-significant (p&gt;0.05). However, the midfielders covered more distance (2425,33±440,42 m) than forward (2146,67±339,64 m), winger (2137,33±615,18 m), fullback (2056,00±512,43 m) and centerback (1960,00±313,51 m) players. The positional requirements of midfielders may be decisive on covered distance during YYIRT.&#x0D; Conclusions. Consequently, it may be said that the young soccer players at different playing positions had similar YYIRT performance and the playing position effect on YYIRT performance could vary depending on league level and individual features of players.&#x0D;

Effect of Training Load Distribution on Aerobic Fitness Measures in Hurling Players

Malone, S, Hughes, B, and Collins, K. Effect of training load distribution on aerobic fitness measures in hurling players. J Strength Cond Res 33(3): 825-830, 2019-The aim of the current investigation was to quantify the training intensity distribution of hurling players and their association with changes in aerobic fitness measures within hurling players. Thirty hurling players (n = 30; age 26.5 ± 3.2 years; height 178.9 ± 3.2 cm; body mass 81.5 ± 4.5 kg) were observed during the pre-championship training period (12 weeks). Aerobic fitness measures (V[Combining Dot Above]O2max), peak treadmill velocity (km·h), heart rates (HRs) at 2 and 4 mmol·L blood lactate concentrations, and Yo-Yo intermittent recovery test performance (Yo-YoIR1) were assessed before and after the training period. Training intensities were categorized using 3 individualized HR zones based on the following criteria: low intensity (≤HR 2 mmol·L), moderate intensity (between HR 2 and 4 mmol·L), and high intensity (≥HR 4 mmol·L). Analysis of 1,025 individual training sessions showed that players spent 58.1 ± 2.5%, 24.3 ± 2.9%, and 17.6 ± 1.3% of time in the low-, moderate-, and high-intensity zones, respectively. The training time spent at high intensity (Zone 3) showed moderate-to-large associations with improvements in S2 (r = 0.80; p = 0.04) and S4 (r = 0.58; p = 0.03). Similar trends were observed for time spent in high intensity and improvements in V[Combining Dot Above]O2max (r = 0.77; p = 0.001) and Yo-YoIR1 performance (r = 0.65; p = 0.05). Hurling players have been shown to spend the majority of training time in low (≤ HR 2 mmol·L) to moderate intensity (between HR 2 and 4 mmol·L) training. However, only the time spent at high intensity (≥90% of maximal HR) was related to changes in aerobic fitness. These results support the usefulness of the quantification of aerobic training load using HR. The study also supports the efficacy of spending elements of training time within the high-intensity zone to increase hurling player's aerobic fitness characteristics.

Possible Hormone Predictors of Physical Performance in Adolescent Team Sport Athletes.

Martin, AC, Heazlewood, IT, Kitic, CM, Lys, I, and Johnson, L. Possible hormone predictors of physical performance in adolescent team sport athletes. J Strength Cond Res 33(2): 417-425, 2019-The research aim of this study was to determine possible hormone predictors of physical performance in adolescent team sport athletes. Saliva samples were collected immediately before performance testing sessions from 114 state squad athletes (77 males, 37 females) participating in either Australian football, basketball, hockey, or netball. Participants completed tests of aerobic and anaerobic capacity, agility, power, and speed. Samples were collected over 22 months at quarterly, six-monthly, and/or yearly intervals depending on the testing schedule of the athlete. Saliva was analyzed for testosterone (T), cortisol (C), estradiol (E), and progesterone (P) levels. A strong negative correlation existed between multistage fitness test performance and T:E ratio (r = -0.76, p = 0.01) in females not taking oral contraceptives, and a strong positive correlation existed between repeat agility total time and estradiol levels (r = -0.71, p = 0.001) in females taking oral contraceptives. In males, strong negative correlations were evident for individual changes in planned agility time and estradiol levels (r = 0.87, p = 0.02), and countermovement jump (CMJ) height and T:C (r = -0.88, p = 0.01). In females taking oral contraceptives, a strong positive correlation was noted between individual change in yo-yo intermittent recovery test performance and T:E (r = 0.74, p = 0.01) and a strong negative correlation was noted between 20-m speed and T:P (r = 0.73, p = 0.01). In females not taking oral contraceptives, a strong negative correlation was found between individual change in CMJ height and T:P (r = -0.72, p = 0.02). The findings show that in adolescent team sport athletes, the P:E, T:E, and the T:P ratios are important predictors of performance in tests of physical capacity. The findings also indicate that estradiol and progesterone have a predictive function in the physical performance of adolescent male team sport athletes.

The effect of Opuntia ficus-indica juice supplementation on oxidative stress, cardiovascular parameters, and biochemical markers following yo-yo Intermittent recovery test.

The aim of the study was to investigate the effect of a flavonoid‐rich fresh fruit juice on cardiovascular, oxidative stress, and biochemical parameters during the yo‐yo intermittent recovery test (YYIRT). Twenty‐two healthy males subjects participated in this study divided into two groups: An experimental group (EG: n = 11) who consumed the antioxidant supplement and a control group (CG: n = 11). All participants performed two test sessions at 07:00 hr before and after 2 weeks of supplementation with Opuntia ficus‐indica juice. Blood samples were taken before (P1) and immediately (P2) after the YYIRT. Our results showed that following the 2,2‐diphenyl‐1‐ picrylhydrazyl (DPPH ●) test, the Opuntia ficus‐indica juice has an antioxidant capacity for capturing free radicals (p < .05) and reducing oxidative stress related to exercise. Concerning biochemical and cardiovascular parameters, our results showed a significant increase on total cholesterol (TC) (p < .01), triglycerides (TG) (p < .05), high‐density lipoprotein (HDL) (p < .01), low‐density lipoprotein (LDL) (p < .01), creatine kinase (CK) (p < .01), lactate deshydrogenase (LDH) (p < .01), glucose (GLC) (p < .01), systolic (SBP), and diastolic blood pressure (DBP) (p < .01) immediately after exercise. However, TC (p < .05), TG (p < .05) and LDL (p < .05), the maximal heart rate (HRmax), the CK (p < .05), and LDH (p < .01) as well as the malondialdehyde (MDA) (p < .01) demonstrated a significant decrease after supplementation of Opuntia ficus‐indica juice before and immediately after YYIRT. However, no significant effect on HDL (p > .05), GLC (p > .05) levels nor the SBP and DBP (p > .05) was observed after supplementation with Opuntia ficus‐indica juice. The supplementation leads to an improvement on YYIRT performance (The total distance covered during the YYIRT,VO 2max, VMA) and the rating of perceived exertion (RPE). Opuntia ficus‐indica juice has a potent antioxidant activity that reduces total and LDL‐cholesterol with only a moderate lowering of HDL‐cholesterol and oxidative stress. Moreover, supplementation decreases muscle damage caused by the endurance exercise.

Yo-Yo Intermittent Recovery Test Performance in Subelite Gaelic Football Players From Under Thirteen to Senior Age Groups.

Roe, M and Malone, S. Yo-Yo intermittent recovery test performance in subelite Gaelic football players from under thirteen to senior age groups. J Strength Cond Res 30 (11): 3187-3193, 2016-Gaelic football is indigenous to Ireland and has similar locomotion profiles to soccer and Australian Football. Given the increasing attention on long-term player development, investigations on age-related variation in Yo-Yo intermittent recovery test level 1 (Yo-YoIR1) performance may provide useful information in talent identification, program design, and player monitoring. Therefore, the aim of this study was to evaluate Yo-YoIR1 performance across Gaelic football age groups. Male participants (n = 355) were recruited from division one, Gaelic football teams. Participants were allocated to one of the 7 groups according to respective age groups from under 13 (U13), under 14, under 15 (U15), under 16 (U16), minor, under 21 (U21), to senior age groups. Total Yo-YoIR1 distance (m) increased progressively from U13 (885 ± 347 m) to U16 (1,595 ± 380 m) equating to a rate of change of 180.2%. In comparison to U13, total distance at minor (1,206 ± 327 m) increased by 136.4%. Subsequent increases were observed in U21 (1,585 ± 445 m) and senior players (2,365 ± 489). Minimum (800-880 m) and maximum (2,240-2,280 m) total distances were comparable for U15, U16, and U21 players. Differences in total distance (m) for all age groups were statistically significant when compared to U13 players (p < 0.002). In comparison to U13 players, the magnitude of differences between age groups for total distance was deemed to be large (effect size > 0.8). Similar trends were observed for maximum velocity and estimated V[Combining Dot Above]O2max. The evolution of Yo-YoIR1 performance in Gaelic football players from adolescents to adulthood highlights how maturation may influence sport-related running ability. Changes in Yo-YoIR1 performance should be closely monitored to optimize interventions for individuals transitioning across age groups.

Effect of speed endurance and strength training on performance, running economy and muscular adaptations in endurance-trained runners.

To investigate the effects of combined strength and speed endurance (SE) training along with a reduced training volume on performance, running economy and muscular adaptations in endurance-trained runners. Sixteen male endurance runners (VO2-max: ~60mlkg(-1)min(-1)) were randomly assigned to either a combined strength and SE training (CSS; n=9) or a control (CON; n=7) group. For 8weeks, CSS replaced their normal moderate-intensity training (~63kmweek(-1)) with SE (2×week(-1)) and strength training (2×week(-1)) as well as aerobic high (1×week(-1)) and moderate (1×week(-1)) intensity training with a reduction in total volume of~58%, whereas CON continued their training (~45kmweek(-1)). In CSS, 400-m and Yo-Yo intermittent recovery test performance was improved by 5% (P<0.01) and 19% (P<0.001), respectively, during the intervention period. Maximal aerobic speed was 0.6kmh(-1) higher (P<0.05), and maximal activity of lactate dehydrogenase subunits 1 and 2 was 17% (P<0.05) higher after compared to before the intervention period. Time to exhaustion and peak blood lactate during an incremental treadmill test was 9% (P<0.05) and 32% (P<0.01), respectively, higher and expression of Na(+)-K(+) pump β1 subunit was 15% higher (P<0.05) after compared to before the intervention period. 10-K performance, maximum oxygen uptake and running economy were unchanged. In CON, no changes were observed. Adding strength and speed endurance training, along with a reduced training volume, can improve short-term exercise capacity and induce muscular adaptations related to anaerobic capacity in endurance-trained runners.

Locomotor, Heart-Rate, and Metabolic Power Characteristics of Youth Women's Field Hockey: Female Athletes in Motion (FAiM) Study

Purpose: The purpose of this study was to quantify the locomotor, heart-rate, and metabolic power characteristics of high-level youth female field hockey matches. Method: Players from the U21 and U17 Canadian women's national teams were monitored during a 4-match test series using Global Positioning System technology. Position (forward, midfielder, defender) and age-group (U21, U17) comparisons were made using 2-way analyses of variance. Results: Forwards played 12 min to 22 min fewer than midfielders and defenders and consequently had lower amounts of total, low-intensity, and moderate-intensity distances. Yet, forwards covered similar amounts of high-intensity running and sprinting distances despite the deficit in playing time. Only 10% to 15% of total distance was characterized by high-intensity running and sprinting, yet the majority of time was spent above 90% maximum heart rate. The distances in high, elevated, and maximal metabolic power categories were greater for U21 than U17 players. Yo-Yo Intermittent Recovery Test performance was related to high-intensity running and maximal metabolic power distance. Conclusions: The current findings highlight positional specificity as well as developmental gaps between age groups for youth female field hockey matches. These match characteristics should be used to assist in establishing appropriate training strategies through the developmental pathway and to assist player achievement to higher standards.

Perceptions of well-being and physical performance in English elite youth footballers across a season

The 2011 English Elite Player Performance Plan (EPPP) stipulates training volumes that could put elite youth players at high risk of non-functional overreaching. The aim of the study was to assess player perceptions of well-being and physical performance to these high training loads. Fourteen academy football players (mean ± SD: age 17 ± 1 years; stature 179 ± 6 cm; body mass 70.8 ± 8.6 kg, at pre-season) completed a perception of well-being questionnaire 1–4 times per week throughout each training block (pre-season, in-season 1, 2, 3). Physical performance tests were carried out at the end of each training block. Increases in training exposure (P < 0.05; = 0.52) and moderate to large deteriorations in perceptions of well-being (motivation, sleep quality, recovery, appetite, fatigue, stress, muscle soreness P < 0.05; = 0.30–0.53) were evident as the season progressed. A moderate decrease in 30 m sprint performance (P < 0.05; = 0.48), a large improvement in Yo-Yo intermittent recovery test performance (P < 0.05; = 0.93) and small decreases in countermovement jump (P > 0.05; = 0.18) and arrowhead agility (P < 0.05; = 0.24) performance were evident as the season progressed. The present findings show an imbalance between stress and recovery in English elite youth players even when players experience lower training exposure than stipulated by the EPPP.

The Effect of Cold Water Immersion on 48-Hour Performance Testing in Collegiate Soccer Players

This randomized, controlled, laboratory study was designed to examine the effect of cold water immersion (CWI) as a recovery modality on repeat performance on the yo-yo intermittent recovery test (YIRT), a widely accepted tool for the evaluation of physical performance in soccer, separated by 48 hours. Twenty-two healthy Division I collegiate soccer players (13 men and 9 women; age, 19.8 ± 1.1 years; height, 174.0 ± 9.0 cm; mass, 72.1 ± 9.1 kg) volunteered as participants during the noncompetitive season. The YIRT was used to induce volitional fatigue and was administered at baseline and again 48 hours later. Athletes progressively increased sprint speed between markers set 20 m apart until pace was failed. Countermovement vertical jump (CMVJ) was used to assess anaerobic power and was measured before YIRT, immediately post-YIRT, and 24 and 48 hours post-YIRT. A 10-cm horizontal visual analog scale was administered immediately, 24 hours and 48 hours post-YIRT to assess perceived fatigue (PF) in the legs. Participants were randomly placed into the CWI or control group. The CWI condition consisted of immersion to the umbilicus in a 12°C pool for 15 minutes, whereas the control group sat quietly for 15 minutes. There were no significant differences between intervention conditions on YIRT performance (control, 4,900 ± 884 m; CWI, 5,288 ± 1,000 m; p = 0.35) or PF (control, 9.4 ± 0.5 cm; CWI, 9.3 ± 0.6 cm; p = 0.65) at 48 hours post-YIRT. There was a main time effect for CMVJ over 48 hours, but no group differences (pre-YIRT, 64.6 ± 11.0 cm; post-YIRT, 66.4 ± 10.9 cm; 24 hours post-YIRT, 63.4 ± 9.9 cm; 48 hours post-YIRT, 63.1 ± 9.4 cm; p = 0.02). This study demonstrated that in collegiate soccer players, CWI performed immediately and 24 hours after induced volitional fatigue did not affect subsequent physical performance estimates.

β-alanine supplementation improves YoYo intermittent recovery test performance

Backgroundβ-alanine supplementation has been shown to improve high-intensity exercise performance and capacity. However, the effects on intermittent exercise are less clear, with no effect shown on repeated sprint activity. The aim of this study was to investigate the effects of β-alanine supplementation on YoYo Intermittent Recovery Test Level 2 (YoYo IR2) performance.MethodsSeventeen amateur footballers were allocated to either a placebo (PLA; N = 8) or β-alanine (BA; N = 9) supplementation group, and performed the YoYo IR2 on two separate occasions, pre and post 12 weeks of supplementation during a competitive season. Specifically, players were supplemented from early to mid-season (PLA: N = 5; BA: N = 6) or mid- to the end of the season (PLA: N = 3; BA: N = 3). Data were analysed using a two factor ANOVA with Tukey post-hoc analyses.ResultsPre supplementation scores were 1185 ± 216 and 1093 ± 148 m for PLA and BA, with no differences between groups (P = 0.41). YoYo performance was significantly improved for BA (+34.3%, P ≤ 0.001) but not PLA (−7.3%, P = 0.24) following supplementation. 2 of 8 (Early – Mid: 2 of 5; Mid – End: 0 of 3) players improved their YoYo scores in PLA (Range: -37.5 to + 14.7%) and 8 of 9 (Early – Mid: 6 of 6; Mid – End: 2 of 3) improved for BA (Range: +0.0 to +72.7%).Conclusions12 weeks of β-alanine supplementation improved YoYo IR2 performance, likely due to an increased muscle buffering capacity resulting in an attenuation of the reduction in intracellular pH during high-intensity intermittent exercise.

Relationship Between Resting Heart Rate And Yo-Yo Intermittent Recovery Test Performance In Elite Badminton Players

Monitoring daily changes in resting heart rate is widely recognized by athletes as an objective measure to estimate physical condition. It has not been well examined, however, whether changes in athletes' resting heart rate indeed associate with changes in their physical condition test performance. In the Japanese national badminton team, Yo-Yo intermittent recovery (YYIR) test has been continuously used to evaluate the players' basic physical condition essential for performing competitive badminton. In this study, we examined a relationship between changes in resting heart rate and changes in YYIR test performance in elite Japanese badminton players. PURPOSE: To examine whether changes in resting heart rate associate with changes in Yo-Yo intermittent recovery test performance in international-class badminton players. METHODS: Fifteen Japanese national badminton team players (23.3+3.1 yrs) volunteered to participate in the study. The subjects performed YYIR test twice in three months during the national team training camps. In each test, total running distances were recorded. In addition, resting heart rate (HR-rest) were collected in the morning before each YYIR test. The subjects were also asked to fill in a questionnaire in which they estimated their subjective feeling of fatigue on a visual analog scale. HR-rest and the scorings of subjective feeling of fatigue were respectively compared between the higher and the lower performed YYIR tests. RESULTS: First, in the morning of the higher performed YYIR test, HR-rest were significantly lower than those in the morning of the lower performed YYIR test (54.3+1.6 vs. 57.7+1.3 beats/min, p<0.01). Moreover, differences in HR-rest between the higher and the lower performed YYIR tests correlated negatively with differences in total running distance between the higher and the lower performed YYIR tests (r=-0.79, p<0.001). In contrast, no significant difference were observed in the scorings of subjectively perceived fatigue between the higher and the lower performed YYIR tests (58.1+5.2 vs. 62.2+4.2 mm, p=0.25). CONCLUSION: Measuring daily changes in resting heart rate might be efficient for elite badminton players to objectively monitor physical condition that underlie their sport performance.

Physiological Aspects of Soccer Refereeing Performance and Training

The role of the referee is far from minimal in the economy of soccer, as very often, particularly in professional soccer, a wrong judgment may have profound implications on the outcome of the game. In this regard, a better knowledge of soccer refereeing can obviously benefit the game. Recent studies have shown that during a competitive match, an elite soccer referee may cover 9-13 km attaining approximately 85-90% and approximately 70-80% of maximal heart rate and maximal oxygen uptake (VO2max), respectively. Of the total distance covered about 4-18% is covered at high intensity. Blood lactate concentration has been reported to be in the range of 4-5 mmol/L; however, during competitive matches, blood lactate concentrations as high as 14 mmol/L have been observed. This figure is similar to that extensively reported for soccer players, specifically paralleling that observed in midfield players. However, compared with players, referees are 15-20 years older, often have a non-professional status and cannot be substituted during the game. Furthermore, this important physical stress superimposes onto a high perceptual-cognitive workload throughout the entire game. In relation to fitness status, referees possess VO2max values somewhat lower than the players they officiate, with mean values in the range of 44-50 mL/kg/min. However, the methods used by the Federation Internationale de Football Association and the Union of European Football Associations to test referee fitness need to be changed as the current fitness tests do not relate to match performance. More task-specific tests such as the Yo-Yo Intermittent Recovery Test (YYIRT) have been devised and validated for use with referees. Given that aerobic performance is positively correlated with match performance, it is important that referees are trained to improve their ability to cover large distances during a match and also to repeat high-intensity efforts. A number of studies have shown large improvements in YYIRT performance following both short-term (12 weeks) and long-term (16 months) high-intensity interval training. Future research needs to focus on a number of important areas including the decision-making ability of referees when officiating under different conditions, such as high thermal strain, and the impact of age on both physical and mental performance.

Match performance of high-standard soccer players with special reference to development of fatigue

The aim of this study was to assess physical fitness, match performance and development of fatigue during competitive matches at two high standards of professional soccer. Computerized time-motion analyses were performed 2-7 times during the competitive season on 18 top-class and 24 moderate professional soccer players. In addition, the players performed the Yo-Yo intermittent recovery test. The top-class players performed 28 and 58% more (P < 0.05) high-intensity running and sprinting, respectively, than the moderate players (2.43 ± 0.14 vs 1.90 ± 0.12 km and 0.65 ± 0.06 vs 0.41 ± 0.03 km, respectively). The top-class players were better (11%; P < 0.05) on the Yo-Yo intermittent recovery test than the moderate players (2.26 ± 0.08 vs 2.04 ± 0.06 km, respectively). The amount of high-intensity running, independent of competitive standard and playing position, was lower (35-45%; P < 0.05) in the last than in the first 15 min of the game. After the 5-min period during which the amount of high-intensity running peaked, performance was reduced (P < 0.05) by 12% in the following 5 min compared with the game average. Substitute players (n = 13) covered 25% more (P < 0.05) ground during the final 15 min of high-intensity running than the other players. The coefficient of variation in high-intensity running was 9.2% between successive matches, whereas it was 24.8% between different stages of the season. Total distance covered and the distance covered in high-intensity running were higher (P < 0.05) for midfield players, full-backs and attackers than for defenders. Attackers and full-backs covered a greater (P < 0.05) distance in sprinting than midfield players and defenders. The midfield players and full-backs covered a greater (P < 0.05) distance than attackers and defenders in the Yo-Yo intermittent recovery test (2.23 ± 0.10 and 2.21 ± 0.04 vs 1.99 ± 0.11 and 1.91 ± 0.12 km, respectively). The results show that: (1) top-class soccer players performed more high-intensity running during a game and were better at the Yo-Yo test than moderate professional players; (2) fatigue occurred towards the end of matches as well as temporarily during the game, independently of competitive standard and of team position; (3) defenders covered a shorter distance in high-intensity running than players in other playing positions; (4) defenders and attackers had a poorer Yo-Yo intermittent recovery test performance than midfielders and full-backs; and (5) large seasonal changes were observed in physical performance during matches.