Fatigue In Players Research Articles

Australian Football Player Work Rate: Evidence of Fatigue and Pacing?

Previous research has suggested elite Australian footballers undertake pacing strategies to preserve high intensity activity later in matches. However, this research used GPS with slow sample rates, did not express performance relative to minutes played during games and used lowly ranked players. Therefore in this study movement was recorded by GPS at 5 Hz. Running performance was expressed per period of the match (rotation) divided into low-intensity activity (LIA, 0.10 to 4.17 m x s(-1)); high-intensity running (HIR, 4.17 to 10.00 m x s(-1)) and maximal accelerations (2.78 to 10.00 m x s(-2)). All data were expressed relative to the first period of play in the match and the magnitude of effects was analyzed with the effect size (ES) statistic and expressed with confidence intervals. The total and LIA distance covered by players did not change by a practically important magnitude during games (ES< 0.20). High intensity running was reduced in both rotations of the second quarter, Q3R2 and both rotations of the fourth quarter (ES -0.30 ± 0.14; -0.42 ± 0.14; -0.30 ± 0.14; -0.42 ± 0.14; and -0.48 ± 0.15 respectively). Maximal acceleration performance was reduced in Q1R2, and each rotation of the second half of matches. When expressed per minute of game time played, total distance and low intensity activity distance are not reduced by a practically important magnitude in AF players during a match. These data are therefore inconsistent with the concept of team sport players pacing their effort during matches. However, both high intensity running and maximal accelerations are reduced later in games, indicative of significant fatigue in players.

Fatigue, H/Q ratios and muscle coactivation in recreational football players

The objective of this study was twofold: first to assess the effect of fatigue on two muscle strength ratios: the conventional ratio – H_{con}/Q_{con} and dynamic control ratio(DCR) – H_{ecc}/Q_{con} and second to assess the coactivation of hamstrings and quadriceps during isokinetic knee flexion/extension. Eight recreational football players (mean ± SD age: 22 ± 2.3 yr; body mass: 85 ± 3.30~kg) volunteered to participate in this study. Peak concentric and eccentric torque of the hamstrings and quadriceps were measured at 120°/s pre and post fatigue using an isokinetic dynamometer. The fatiguing protocol consisted of 50 maximal concentric knee flexion/extension repetitions. Using surface EMG, peak RMS of the biceps femoris and vastus lateralis were measured in order to calculate muscle coactivation during extension and flexion of the knee. Paired samples t-tests concluded that there was a significant increase in both the conventional ratio (0.75 vs. 1.02) and the DCR (0.88 vs. 1.08) following fatigue. A significant increase in hamstring coactivation during concentric quadriceps muscle actions following fatigue was also observed (18.6 vs. 21.3%. These data contribute to the literature aiding the future development of the DCR and its use in injury prevention and rehabilitation strategies.

Overload Creatine Supplementation Effect On Volleyball Players Strength

PURPOSE: To determine the effects of overload oral creatine supplementation during 7 days, on strength gain and delayed muscle fatigue of Volleyball players. METHODS: Twenty four male Volleyball players, with an average age of 21.4 yrs (±2.4) took part in this study: 12 constituted the placebo group (PG) and ingested 20 g of manitol per day, and the others ingested 20 g of creatine monohydrate (CG) per day, distributed by four doses of 5 g each (in the morning, after lunch and before and immediately after the training). To measure strength levels, all the athletes performed a Squat Jump (SJ) and a Counter Movement Jump (CMJ) in the Ergo Jump (Globus Ergo Tester) at the beginning and in the end of the training session, both before the supplementation program started (pretest) and after 7 days (posttest). The groups' strength levels comparisons between pretest and posttest and between the beginning and the end of each training session were made using two-way ANOVA with repeated measures. RESULTS: There were no differences in SJ performance between pretest and posttest either in PG (0.64 + 0.04 vs. 0.66 + 0.07 at beginning, and 0.64 + 0.05 vs. 0.65 + 0.04 at the end of training session) or in CG (0.60 + 0.07 vs. 0.59 + 0.09 at beginning, and 0.59 + 0.07 vs. 0.61 + 0.06 at the end of training session). Similarly, there were no differences in CMJ performance between pretest and posttest either in PG (0.65 + 0.04 vs. 0.67 + 0.03 at beginning, and 0.66 + 0.03 vs. 0.66 + 0.03 at the end of the training session) or in CG (0.61 + 0.07 vs. 0.60 + 0.08 at beginning, and 0.60 + 0.07 vs. 0.61 + 0.07 at the end of the training session). CONCLUSIONS: The overload creatine supplementation failed to induce an increase in strength gain and delayed muscle fatigue of Volleyball players.

TESTES DE CAMPO PARA MONITORAR DESEMPENHO, FADIGA E RECUPERAÇÃO EM BASQUETEBOLISTAS DE ALTO RENDIMENTO

The purpose of this study was to examine a field tests for monitoring changes in performance, fatigue and recovery in high bas performance basketball players. The vertical jump, triple horizontal consecutive jump, T test (C40) and Yo-Yo intermittent endurance test (YO-YO) of the normal training group (NT) and intensified training group (IT) were measured at the beginning of the training (T0), post six weeks training (T1) and post 2-week taper (T2). The data were examined using a two-factor (group x moment) ANOVA with repeated measures. The post hoc HSD Tukey was utilized when necessary. The significance level adopted was 5%. The IT group showed increment at C40 and performance decrement at YO-YO after intensified training (T0-T1). The NT revealed increment at YO-YO between T0-T2. The results suggest that YO-YO may be a practical test for assessing changes in performance, fatigue and recovery of basketball players.

Evaluation Of High Level Tennis Players In A Competition By Measuring The Androgens/Corticosteroids Urinary Ratio

Tennis is an intermittent intensity sport with an average intensity during matches of 55 - 65 % VO2 max and with a duration of 1 - 5 hours in high level tennis players. Physical activity generates stress situations which can be appreciated as hormonal changes depending on effort intensity and duration. Urinary hormones and their metabolites have been used in order to evaluate physical effort, but more knowledge is needed regarding this topic. PURPOSE: The aim of this study is to evaluate physical effort generated during an official match in high level tennis players by using different urinary anabolic / catabolic hormone ratios and to determine which of them could be the best indicator of fatigue analysis. METHODS: Eight professional tennis players, ranked in the top 100 ATP, performed this study (Age: 24,88 ±2,59; Height: 1,80 ±0,05; Weight: 75,63 ±5,21). Urine samples were collected before (60 min before competition) and after (60 min after competition) a tournament match (quarterfinals corresponding to the Spanish Tennis Master). The matches started at 11 a.m and they had an average duration of 90 ± 18 min. Urinary testosterone (T), DHEA (D), cortisol (C), T/C ratio and DHEA/C steroid ratio were determined by using chromatographic techniques for their analysis: GC/MS and GC/MS/MS. The density of urinary samples was in the range of 1,005 - 1,025 g/mL, and the pH was in the normal range of 4,7 - 7,8. The creatinine levels of all the samples were determined in order to report the steroid concentrations related to this urine parameter. The creatinine concentration was determined by spectrophotometry using Sigma Kit "Creatinine 555 - A&". The Wilcoxon test was performed for statistical analysis. Ap value of <0.05 was used to determine statistical significance. RESULTS: The DHEA/C ratio decreased (2,97 ± 0,46 to 0,77 ± 0,26, p<0,05), T/C ratio decreased (1,04 ± 0,35 to 0,53 ± 0,11) although statistical significance was not reached. These ratio changes were due to a decrease in urinary androgens excretion as well as an increase in urinary corticosteroids excretion. A bigger decrease in suprarenal androgens may indicate a greater implication of this glandule in the early phases of recovery. CONCLUSION: The DHEA/C urinary ratio could be a useful parameter in order to gain information on physical effort and fatigue in high level tennis players.

Applied Physiology of Rugby League

Rugby league football is played in several countries worldwide. A rugby league team consists of 13 players (6 forwards and 7 backs), with matches played over two 40-minute halves separated by a 10-minute rest interval. Several studies have documented the physiological capacities of rugby league players and the physiological demands of competition, with the physiological capacities of players and the physiological demands of competition increasing as the playing level is increased. However, there is also evidence to suggest that the physiological capacities of players may deteriorate as the season progresses, with reductions in muscular power and maximal aerobic power and increases in skinfold thickness occurring towards the end of the rugby league season, when training loads are lowest and match loads and injury rates are at their highest. Player fatigue and playing intensity have been suggested to contribute to injuries in rugby league, with a recent study reporting a significant correlation (r=0.74) between match injury rates and playing intensity in semi-professional rugby league players. Studies have also reported a higher risk of injury in players with low 10-m and 40-m speed, while players with a low maximal aerobic power had a greater risk of sustaining a contact injury. Furthermore, players who completed <18 weeks of training prior to sustaining their initial injury were at greater risk of sustaining a subsequent injury. These findings provide some explanation for the high incidence of fatigue-related injuries in rugby league players and highlight the importance of speed and endurance training to reduce the incidence of injury in rugby league players. To date, most, but not all, studies have investigated the movement patterns and physiological demands of rugby league competition, with little emphasis on how training activities simulate the competition environment. An understanding of the movement patterns and physiological demands of specific individual positions during training and competition would allow the development of strength and conditioning programmes to meet the specific requirements of these positions. In addition, further research is required to provide information on the repeated effort demands of rugby league. A test that assesses repeated effort performance and employs distances, tackles and intensities specific to rugby league, while also simulating work-to-rest ratios similar to rugby league competition, is warranted.

Can lower limb fatigue be reliably induced in male athletes?

Basketball, soccer and volleyball players incur a high incidence of lower limb overuse injuries, which have been attributed to factors including player fatigue and repetitive jumping movements typical of these sports. As fatigued muscles are less able to absorb the loads generated during landing, it is thought that fatigue may contribute to the development of overuse knee injuries by increasing the repetitive shock transferred to patellar tendon during landing. However, before the relationship between fatigue and lower limb injuries can be systematically investigated, it is imperative to establish a reliable protocol to induce lower limb fatigue.

Incidence of injuries in the New Zealand national rugby league sevens tournament

This study investigated the incidence, site, nature and causes of injuries sustained in the New Zealand national rugby league sevens tournament. A total of 218 players competing in 47 matches were studied. All injuries sustained within the tournament were prospectively recorded. Injuries were categorised according to the severity assessment at the time of the injury. Information obtained included the time, site, nature and cause of the injury. The incidence of injury was 497.6 per 1000 playing hours. More than 40% (216.1 per 1000) of injuries sustained occurred within the lower limbs. The shoulder was the single most commonly injured site (78.6 per 1000). Sprains were the most common injury type (189.9 per 1000). The ball-carrier sustained significantly more (p<0.05) injuries than the tackling player (216.1 per 1000 [43.4%] versus 117.8 per 1000 [23.7%]). There were significantly more injuries on the first day of competition than on the second day of competition (600.4 per 1000 [76.3%] versus 320.9 per 1000 [23.7%]). The findings of higher injury rates on the first day of competition and during the second period of matches suggest that playing intensity and player fatigue may contribute to injuries in rugby league sevens.

Risk Factors for Injury in Subelite Rugby League Players

Background Although player fatigue and playing intensity have been suggested to contribute to injuries in rugby league players, no study has confirmed if the level of physical fitness is a risk factor for injury in rugby league players. The aim of this study was to identify risk factors for injury in subelite rugby league players. Hypothesis Low physical fitness levels are risk factors for injury in subelite rugby league players. Study Design Cohort study; Level of evidence, 2. Methods One hundred fifty-three players from a subelite rugby league club underwent preseason measurements of muscular power (vertical jump), speed (10- and 40-m sprint), and maximal aerobic power (multistage fitness test) over 4 competitive seasons. All injuries sustained by players were prospectively recorded over the 4 competitive seasons. Results The risk of injury was greater in players with low 10- and 40-m speed. Players with a low maximal aerobic power had a greater risk of sustaining a contact injury. In addition, players who completed less than 18 weeks of training before sustaining their initial injuries were at greater risk of sustaining a subsequent injury. Conclusions Subelite rugby league players with low speed and maximal aerobic power are at an increased risk of injury. In addition, players who complete less than 18 weeks of training before sustaining an initial injury are at greater risk of sustaining a subsequent injury. These findings highlight the importance of speed and endurance training to reduce the incidence of injury in subelite rugby league players.

Position related analysis of the appearance of and relationship between post-match physical and mental fatigue in university rugby football players

Objective: The relationship between physical and mental fatigue in rugby players after a match was examined, taking into account the position played. Methods: The Profile of Mood State (POMS) test,...

Incidence of injury in junior and senior rugby league players.

Rugby league is an international collision sport played at junior, amateur, semi-professional and professional levels. Due to the high numbers of physical collisions and tackles, musculoskeletal injuries are common. A large percentage of injuries result in long-term employment and study limitations, medical costs and loss of income. Review articles addressing the applied physiology of rugby league and common rugby league injuries have been published. However, both of these review articles have focused on the professional rugby league player. This review addresses the extent of the injury problem in rugby league in all levels of competition (i.e. junior, amateur, semi-professional and professional). The incidence of rugby league injuries typically increases as the playing level is increased. The majority of studies have shown that the head and neck is the most common site of match injuries in senior rugby league players, while knee injuries are the most common site of injury in junior rugby league players. Muscular injuries are the most common type of injury sustained by senior rugby league players, while junior rugby league players more commonly sustain fractures. Injuries are most commonly sustained in tackles, by the tackled player. Thigh and calf strains are the most common injuries sustained during rugby league training, while overexertion is the most common cause of training injuries. Player fatigue may influence the incidence of injury, with most sub-elite (amateur and semi-professional) rugby league injuries occurring in the second half of matches or the latter stages of training sessions. The majority of training injuries occur in the early stages of the season, while match injuries occur in the latter stages of the season, suggesting that changes in training and playing intensity may influence the incidence of injury in rugby league. Injury prevention studies are required to reduce the incidence, severity and cost of rugby league injuries. These injury prevention strategies could include coaching on defensive skills, correct tackling technique, correct falling technique and methods to minimise the absorption of impact forces in tackles. Game-specific attacking and defensive drills practised before and during fatigue may also encourage players to make appropriate decisions under fatigued conditions and apply learnt skills during the pressure of competitive matches. Further studies investigating risk factors for injury in junior and senior rugby league players, injuries sustained by specific playing positions and the influence of injuries on playing performance are warranted.

Testing isokinetic muscular fatigue of shoulder internal and external rotation in elite junior tennis players.

Single group, post-test only descriptive analysis of isokinetically measured shoulder internal and external rotation muscular fatigue. To determine whether differences in isokinetically measured muscular fatigue exist between shoulder external (ER) and internal rotation (IR) and between the dominant (DOM) and nondominant (NDOM) extremity in elite junior tennis players. The importance of the rotator cuff in stabilizing the humeral head during repetitive athletic overhead motions has been identified in biomechanical investigations. The application of exercise to improve muscular function of the shoulder and prevent injury is a common practice in physical therapy, but shoulder fatigue in tennis players has received little attention in the literature. Seventy-two elite junior tennis players (ages 12 to 18) underwent bilateral isokinetic testing with 90 degrees of glenohumeral joint abduction. A muscular fatigue protocol consisting of 20 maximal-effort concentric contractions of ER and IR was used to measure muscular fatigue at 300 degrees/s. A relative fatigue ratio was calculated by dividing the work in the last 10 repetitions by the work in the first 10 repetitions. Higher fatigue ratios indicate improved muscular fatigue resistance. A 2x2 ANOVA was used to assess differences in fatigue in DOM versus NDOM arm, and in IR versus ER. Relative muscular fatigue ratios for ER and IR were 69.1+/-15.3% and 82.93+/-14.81% for the DOM extremity, respectively. In the NDOM extremity, ER and IR fatigue ratios were 71.13+/-15.07% and 83.9+/-16.5%, respectively. These results indicate significant differences between the fatigue ratios for ER and IR. No significant difference between extremities in either ER or IR relative fatigue ratios was found. These data have implications for rehabilitation and conditioning of the rotator cuff musculature.

Grip Strength and Fatigue in Junior College Tennis Players

Change in grip strength over 30 trials was documented in two samples of junior college tennis players to assess possible fatigue. Eight men and eight women performed 30 maximum-grip strength tests with 25-sec. rests between trials. Significant positive correlations (.38 and .53 for men and women) were observed between grip strength and trials. In practical terms, grip strength did not change over 30 trials in these tennis players. The data suggested that the repetitive gripping patterns used by these players in tennis play resulted in consistent maximum-grip strengths across 30 trials.

Physiology of ice hockey.

Ice hockey is characterized by high intensity intermittent skating, rapid changes in velocity and duration, and frequent body contact. The typical player performs for 15 to 20 minutes of a 60-minute game. Each shift lasts from 30 to 80 seconds with 4 to 5 minutes of recovery between shifts. The intensity and duration of a particular shift determines the extent of the contribution from aerobic and anaerobic energy systems. The high intensity bursts require the hockey player to develop muscle strength, power, and anaerobic endurance. The length of the game and the need to recover quickly from each shift demands a good aerobic system. Physical characteristics of elite players show that defensemen are taller and heavier than forwards probably due to positional demands. Hockey players are mesomorphic in structure. They are relatively lean since excess mass is detrimental to their skating performance. There is a large interindividual variability in VO2 during skating. Both the aerobic and anaerobic energy systems are important during a hockey game. Peak heart rates during a shift on the ice exceed 90% of HRmax with average on-ice values of about 85% of HRmax. Blood lactate is elevated above resting values confirming the anaerobic nature of the game. Glycogen depletion studies show a preferential utilisation of glycogen from the slow twitch fibres but also significant depletion from the fast twitch fibres. Elite hockey players display a muscle fibre composition similar to untrained individuals. Physiological profiles of elite hockey teams reveal the importance of aerobic endurance, anaerobic power and endurance, muscular strength and skating speed. Training studies have attempted to improve specific components of hockey fitness. Using traditional laboratory tests, a season of hockey play shows gains in anaerobic endurance but no change in aerobic endurance. On-ice tests of hockey fitness have been recommended as an essential part of the hockey player's physiological profile. Existing training procedures may develop chronic muscular fatigue in hockey players. Lactic acidosis is associated with the onset and persistence of muscle fatigue. Muscle force output remains impaired throughout the hockey player's typical cycle of practices and games. A supplementary programme of low-intensity cycling during the competitive phase of training was unsuccessful in altering VO2max. Strength decrements during the hockey season are attributed to a lack of a specifically designed strength maintenance programmes. On-ice and off-ice training programmes should focus on the elevation of aerobic endurance, anaerobic power and endurance, muscular strength and skating speed.

Reducing Travelling Costs and Player Fatigue in the National Basketball Association

The costs of the current National Basketball Association (NBA) schedule have had deleterious effects on the financial position of the league. The 22 teams travel an unnecessary number of airline miles, resulting in increased fatigue for the players and dollar losses to the owners. We have considered several optimization methods to lower the total number of passenger miles the league travels. We have succeeded in developing efficient schedules, by a combination of these techniques, for the 1978–1979 and 1979–1980 seasons. These schedules satisfy the league's constraints and would have led to savings of $757,000 or 20.4% over the NBA's current schedule. The NBA is considering our proposal to schedule the 1980–1981 and 1981–1982 seasons.