Creatine kinase and its relationship with match performance in elite Australian Rules football

Does Physical Conditioning Influence Performance Attenuation and Recovery in Gaelic Football?

PURPOSE

This study investigated the influence of components of fitness on measures of performance attenuation and recovery following Gaelic football match play.

METHODS

Measurements of players' anthropometric characteristics, body composition, running speed, lower-body strength and power, blood lactate concentrations, running economy, and maximal aerobic capacity (V˙O2max) were taken over 2 separate days 1 week prior to a competitive match. Creatine kinase, countermovement jump height, drop jump height, contact time, reactive strength index, and perceptual responses were tested prematch, at full time, 24 hours postmatch, and 48 hours postmatch.

RESULTS

Multiple components of fitness were associated with reduced performance attenuation and improved recovery responses (adjusted R2 = 9.8%-27.6%; P < .05). Players were divided into higher-standard and lower-standard V˙O2max (higher standard: 57.4 [4.2] mL·kg-1·min-1; lower standard: 45.3 [3.8] mL·kg-1·min-1) and relative squat (higher standard: 1.46 [0.11] 1-repetition-maximum kg·body mass-1; lower standard: 1.20 [0.08] 1-repetition-maximum kg·body mass-1) groups. After adjusting for prematch baseline differences, there were significant differences between V˙O2max groups in drop jump height at 24 hours postmatch (ηp2=.078-.154; P < .05) and countermovement jump height at 48 hours postmatch (ηp2=.134; P < .05), where the lower-standard group displayed larger decrements. In addition, there were significant differences between relative squat groups at all postmatch time points in contact time (ηp2=.156-.194; P < .05) and reactive strength index (ηp2=.127-.223; P < .05) and in perceptual responses at 24 hours postmatch (ηp2=.152; P < .05), where the lower-standard group expressed larger decrements.

CONCLUSION

Coaches should prioritize the development of aerobic capacity and neuromuscular function as an effective method of reducing performance attenuation and enhancing recovery kinetics in Gaelic football.

Custom-Fitted Compression Garments Enhance Recovery From Muscle Damage in Rugby Players

ABSTRACT

Brown, F, Jeffries, O, Gissane, C, Howatson, G, van Someren, K, Pedlar, C, Myers, T, and Hill, JA. Custom-fitted compression garments enhance recovery from muscle damage in rugby players. J Strength Cond Res 36(1): 212-219, 2022-to evaluate the effects of custom-fitted compression garments (CG) on recovery from muscle damage in rugby players. Forty-five players were tested for lower-body strength, power, and indices of muscle damage before completing a damaging protocol (20 × 20-m sprints with 5-m deceleration, 100 drop jumps). Players were randomly assigned to wear either custom-fitted (CF, n = 13), or standard-sized CG (SSG, n = 16), or to receive sham ultrasound therapy (CON, n = 16) immediately after exercise. Players were retested immediately, then after 24 and 48 hours. Strength recovery was significantly different between groups (F = 2.7, p = 0.02), with only CF recovering to baseline values by 48 hours (p = 0.973). Time × condition effects were also apparent for creatine kinase activity (χ2 = 30.4, p < 0.001) and midthigh girth (F = 3.7, p = 0.005), with faster recovery apparent in CF compared with both CON and SSG (p < 0.05). Custom-fitted CG improved strength recovery and indices of muscle damage in rugby players, compared with controls and standard-sized garments. Athletes and coaches would be advised to use appropriately fitted CG to enhance strength recovery after damaging exercise.

Apples and oranges? Comparing player performances between the Australian Football League and second-tier leagues

This study developed a model to determine the extent to which player performance objectively differs between various Australian football (AF) leagues. Champion Data (CD) ranking points were obtained during the 2016-2019 seasons, for all players across the Australian Football League (AFL) and the 10 main second-tier AF leagues. Data pertaining to each player's age, playing position and the AF leagues in which they competed in were also collected. Phase One investigated the difference between the AFL and the senior second-tier leagues in which AFL affiliate teams participate. Post-hoc tests indicated that objective player performance was substantially different between the AFL and each of the four senior second-tier leagues (effects ranging from 16.8 to 21.6 CD ranking points). Phase Two investigated the difference between the second-tier leagues from which players are traditionally drafted by an AFL club. Post-hoc tests indicated that objective player performance was substantially different between the four senior second-tier leagues as well as the under-18 national championships, in comparison to each of the reserve and under-18 state leagues. Professional sporting organisations may utilise the methods provided here as an example of what could be implemented to support decisions regarding player contracting, recruitment and team selection.

Impact of Preceding Workload on Team Performance in Collegiate Men's Ice Hockey

ABSTRACT

Neeld, KL, Peterson, BJ, Dietz, CC, Cappaert, TA, and Alvar, BA. Impact of preceding workload on team performance in collegiate men's ice hockey. J Strength Cond Res 35(8): 2272-2278, 2021-Although the workload-injury relationship has received ample research attention, the relationship between prior workload and performance in team sport remains poorly understood. The purpose of this study was to determine if preceding workloads influence competition performance in men's ice hockey. On-ice workload data were collected from all players on a NCAA Division I men's ice hockey team for 2 consecutive seasons. Training and match workloads were characterized using 7 variables (player load, skating load, explosive efforts, high force strides, player load·min-1, skating load·min-1, and average stride force·lb-1). Team performance was calculated as the difference between the subject and opposing teams' shots on goal. Nine separate ANCOVAs were performed to assess the effect of workload across quartiles of 5 different time spans (1,3,5,7 and 28 days), and low, typical, and high zones of 4 time ratios (1/28, 3/28, 5/28, and 7/28) days) on team shot differential, accounting for season quarter and rank differential between the subject and opposing team. Alpha was set a priori to 0.05. Of all workload measures included in each analysis, only 7-day high force strides (p < 0.01, eta2 = 0.72), and 7-day player load·min-1 (p < 0.05, eta2 = 0.50) had a significant effect on shot differential. Measures of skating intensity in the week preceding competition have the largest impact on team performance. These results can be used by performance coaches to examine tests of speed, power, strength, and conditioning to identify potential limiting factors to high-intensity skating, design training programs with specific need-based emphases, and make recommendations for weekly management of high-intensity skating loads.

Does perceived wellness influence technical-tactical match performance? A study in youth international rugby using partial least squares correlation analysis

The purpose of this study was to determine the relationship between matchday wellness status and a technical-tactical performance construct during rugby match-play. One hundred and thirty-three male rugby union players (73 forwards and 60 backs) from five under-18 national squads who participated in the under-18 Six Nations competition completed a subjective wellness questionnaire on each matchday morning. Players subjectively rated each item (sleep quality, fatigue, muscle soreness, stress and mood) on a five-point Likert scale to calculate their daily wellness status (i.e. difference between matchday and baseline perceived wellness). Technical-tactical performance during match-play was quantified by coding individual key performance indicators (e.g. number of carries, number of tackles). Partial least squares correlation analysis (PLSCA) was employed to compute the latent variables of perceived wellness status (X matrix) and technical-tactical performance (Y matrix) for each player observation (n = 271). The latent variables are a construct of each variable group, enabling higher dimensional data to be visualised more simply. Linear mixed-effect models were later conducted to assess the relationships between the latent variables. The effect of perceived wellness status on technical-tactical performance was statistically significant in forwards (p = .042), not statistically significant in backs (p = .120) and accounted for 4.9% and 1.9% variance in the technical-tactical performance construct, respectively. The findings of this study suggest that perceived wellness status can influence technical-tactical match performance, but the practical significance of these findings should be interpreted with caution given the amount of variance in technical-tactical performance accounted by the models.

Running Performance Is Correlated With Creatine Kinase Levels and Muscle Soreness During an Olympic Games in Hockey

PURPOSE

To compare the global positioning system- and accelerometry-derived running demands, creatine kinase (CK), and self-reported wellness during an Olympic Games in international hockey.

METHODS

Data were collected across 5 games during the 2016 Rio Olympic Games. Global positioning system units (10 Hz) were used to assess the running demands, accelerations, and decelerations of outfield players in a men's hockey squad with matches 2 to 5 compared with match 1. CK was used as a marker of muscle damage, and self-reported psychometric questionnaires were used to assess wellness, with each of the 5 matches compared with precompetition assessments.

RESULTS

There were significant increases (P < .05) in either, or both, absolute and relative total distance, player load, high-speed running distance, sprint distance, and accelerations and decelerations, compared with baseline. There was a significant decrease (P < .05) in maximal velocity by match 5. CK significantly increased from match 1 to 5 and displayed significant correlations with total distance (r = .55) and player load (r = .41). Muscle soreness correlated with total distance and player load, with other wellness markers unchanged compared with baseline.

CONCLUSIONS

International hockey athletes may maintain or increase running activities over the course of an Olympic tournament; however, this may be impacted by situational (match score/outcome) and environmental (ambient temperature) factors. Despite CK and muscle soreness displaying relationships with running variables, further work is needed to establish their individual value in monitoring international hockey athletes.

Clinical Practice Guidelines for Exertional Rhabdomyolysis: A Military Medicine Perspective

ABSTRACT

Exertional rhabdomyolysis (ER) is an uncommon condition with a paucity of evidence-based guidance for diagnosis, management, and return to duty or play. Recently, a clinical practice guideline for diagnosis and management of ER in warfighters was updated by a team of military and civilian physicians and researchers using current scientific literature and decades of experience within the military population. The revision concentrated on challenging and controversial clinical questions with applicability to providers in the military and those in the greater sports medicine community. Specific topics addressed: 1) diagnostic criteria for ER; 2) clinical decision making for outpatient versus inpatient treatment; 3) optimal strategies for inpatient management; 4) discharge criteria; 5) identification and assessment of warfighters/athletes at risk for recurrent ER; 6) an appropriate rehabilitative plan; and finally, 7) key clinical questions warranting future research.

Gaelic Football Match-Play: Performance Attenuation and Timeline of Recovery

This study investigated acute changes in markers of fatigue and performance attenuation during and following a competitive senior club-level Gaelic football match. Forty-one players were tested immediately pre-match, at half-time, full-time, 24 h post-match and 48 h post-match. Creatine kinase, drop jump height and contact-time, reactive strength index, countermovement jump height and perceptual responses were assessed at the aforementioned time-points. 18 Hz global positioning system devices were used to record players in-game workload measures. Compared to pre-match, perceptual responses (−27.6%) and countermovement jump height (−3.9%) were significantly reduced at full-time (p < 0.05). Drop jump height (−8.8%), perceptual responses (−27.6%), reactive strength index (−15.6%) and countermovement jump height (−8.6%) were significantly lower 24 h post-match (p < 0.05). Pre-match creatine kinase was significantly increased (+16.2% to +159.9%) when compared to all other time-points (p < 0.05). Total distance, total accelerations, total sprints, sprint distance and average heart rate were all correlated to changes in perceptual responses (r = 0.34 to 0.56, p < 0.05). Additionally, maximum speed achieved (r = 0.34) and sprint distance (r = 0.31) were significantly related to countermovement jump changes (p < 0.05), while impacts (r = 0.36) were correlated to creatine kinase increases (p < 0.05). These results demonstrate that Gaelic football match-play elicits substantial neuromuscular, biochemical and perceptual disturbances.

Muscle Damage During a Soccer World Cup Preparatory and Competition Period

PURPOSE

To report creatine kinase ([CK]) responses during a soccer World Cup preparatory and first-leg period and to determine the influence of aerobic fitness on postmatch [CK] responses.

METHODS

Eleven national-team players were analyzed in this study. A lactate threshold test was performed during the first 3 d, whereas fingertip blood was drawn most mornings (21 out of 30 d) for [CK] measurements. One-way repeated-measures analysis of variance was used for determining the effect of time on [CK] measurements, whereas Pearson correlation coefficient was used for assessing associations between the changes in [CK] and velocities associated with blood lactate concentrations of 2 (v2) and 4 mmol·L-1 (v4).

RESULTS

Peak [CK] concentrations were consistently reached on the first day after the match with values of 474 (261), 520 (419), and 460 (126) U·L-1 but with no significant differences between them. [CK] concentrations returned to prematch values (331 [201] U·L-1) on the second day after the match. The change in [CK] concentration between prematch and postmatch day was largely correlated (r = .614, P = .044) with v2.

CONCLUSIONS

Top-level soccer players display low levels of muscle damage during official tournaments, and they recover before the next match. Postmatch muscle damage is greater in players with higher aerobic endurance because this fitness quality enables them to execute high-intensity activities known to be a major contributor to muscle damage.

Deceleration, Acceleration, and Impacts Are Strong Contributors to Muscle Damage in Professional Australian Football

Gastin, PB, Hunkin, SL, Fahrner, B, and Robertson, S. Deceleration, acceleration, and impacts are strong contributors to muscle damage in professional Australian football. J Strength Cond Res 33(12): 3374-3383, 2019-The purpose of this study was to investigate the relationships between serum creatine kinase [CK], an indirect marker of muscle damage, and specific indices of match load in elite Australian football. Twenty-six professional players were assessed during a competitive Australian Football League (AFL) season. [CK] was collected 24-36 hours before match and 34-40 hours after match during 8 in-season rounds. An athlete-tracking technology was used to quantify match load. Generalized estimating equations and random forest models were constructed to determine the extent to which match-load indices and pre-match [CK] explained post-match [CK]. There was a 129 ± 152% increase in [CK] in response to AFL competition. Generalized estimating equations found that number of impacts >3g (p = 0.004) and game time (p = 0.016) were most strongly associated with post-match [CK]. Random forest, with considerably lower errors (130 vs. 316 U·L), found deceleration, acceleration, impacts >3g, and sprint distance to be the strongest predictors. Pre-match [CK] accounted for 11% of post-match [CK], and considerable interindividual and intraindividual variability existed in the data. Creatine kinase, an indicator of muscle damage, was considerably elevated as a result of AFL competition. Parametric and machine-learning analysis techniques found several indices of physical load associated with muscle damage during competition, with impacts >3g and high-intensity running variables as the strongest predictors. [CK] may be used as a global measure of muscle damage in field team sports such as AF, yet with some caution given cost, invasiveness, and inherent variability. Quantifying physical load and the responses to that load can guide athlete management decision-making and is best undertaken within a suite of practical, sport-specific measures, where data are interpreted individually and with an understanding of the limitations.

Effects of Cupping Therapy in Amateur and Professional Athletes: Systematic Review of Randomized Controlled Trials

OBJECTIVE

Despite the recent re-emergence of the process of cupping by athletes, supporting evidence for its efficacy and safety remains scarce. This systematic review aims to summarize the evidence of clinical trials on cupping for athletes.

METHODS

SCOPUS, Cochrane Library, PubMed, AMED, and CNKI databases were searched from their inception to December 10, 2016. Randomized controlled trials on cupping therapy with no restriction regarding the technique, or cointerventions, were included, if they measured the effects of cupping compared with any other intervention on health and performance outcomes in professionals, semi-professionals, and leisure athletes. Data extraction and risk of bias assessment using the Cochrane Risk of Bias Tool were conducted independently by two pairs of reviewers.

RESULTS

Eleven trials with n = 498 participants from China, the United States, Greece, Iran, and the United Arab Emirates were included, reporting effects on different populations, including soccer, football, and handball players, swimmers, gymnasts, and track and field athletes of both amateur and professional nature. Cupping was applied between 1 and 20 times, in daily or weekly intervals, alone or in combination with, for example, acupuncture. Outcomes varied greatly from symptom intensity, recovery measures, functional measures, serum markers, and experimental outcomes. Cupping was reported as beneficial for perceptions of pain and disability, increased range of motion, and reductions in creatine kinase when compared to mostly untreated control groups. The majority of trials had an unclear or high risk of bias. None of the studies reported safety.

CONCLUSIONS

No explicit recommendation for or against the use of cupping for athletes can be made. More studies are necessary for conclusive judgment on the efficacy and safety of cupping in athletes.

Proposal of a Global Training Load Measure Predicting Match Performance in an Elite Team Sport

Aim: The use of external and internal load is an important aspect of monitoring systems in team sport. The aim of this study was to validate a novel measure of training load by quantifying the training-performance relationship of elite Australian footballers.

Methods: The primary training measure of each of 36 players was weekly load derived from a weighted combination of Global Positioning System (GPS) data and perceived wellness over a 24-week season. Smoothed loads representing an exponentially weighted rolling average were derived with decay time constants of 1.5, 2, 3, and 4 weeks. Differential loads representing rate of change in load were generated in similar fashion. Other derived measures of training included monotony, strain and acute:chronic ratio. Performance was a proprietary score derived from match performance indicators. Effects of a 1 SD within-player change below and above the mean of each training measure were quantified with a quadratic mixed model for each position (defenders, forwards, midfielders, and rucks). Effects were interpreted using standardization and magnitude-based inferences.

Results: Performance was generally highest near the mean or ~1 SD below the mean of each training measure, and 1 SD increases in the following measures produced small impairments: weekly load (defenders, forwards, and midfielders); 1.5-week smoothed load (midfielders); 4-week differential load (defenders, forwards, and midfielders); and acute:chronic ratio (defenders and forwards). Effects of other measures in other positions were either trivial or unclear.

Conclusion: The innovative combination of load was sensitive to performance in this elite Australian football cohort. Periods of high acute load and sustained increases in load impaired match performance. Positional differences should be taken into account for individual training prescription.

SIgA response and incidence of upper respiratory tract infections during intensified training in youth basketball players

The aim of the present study was to examine the effect of an intensified training phase followed by a tapering phase on the salivary immunoglobulin A concentration and on the upper respiratory tract infection (URTI) symptoms in young male basketball players. The session rating of perceived exertion method was used to quantify the internal training load, and the Wisconsin Upper Respiratory Symptom Survey-21 questionnaire was used to assess URTI symptoms. The Yo-Yo IR1 test and saliva collection were carried out at the beginning of the study (T1), after the intensified phase (T2), and after tapering (T3). A higher internal training load was observed for the intensified phase compared with the tapering phase (t=19.10; p<0.001), and a significant decrease in salivary immunoglobulin A concentration was detected (F=7.48; p=0.004) at T3 compared to T1 (p=0.02) and T2 (p=0.05). However, there was no significant difference between phases for severity of URTI (χ²= 2.83; p=0.242). The Yo-Yo IR1 test performance increased from T2 and T3 compared to T1 (F=58.24; p<0.001). There was no significant effect of aerobic fitness level on salivary immunoglobulin A response (F=1.095; p=0.344). In summary, the present findings suggest that an intensified training load followed by a tapering period negatively affects the mucosal immune function with no significant change in severity of URTI in young basketball players.

Applied sport science of rugby league

Rugby league is a team sport in which players engage in repeated high-intensity exercise involving frequent collisions. Recent research, much of which has involved global positioning system (GPS) technology, has provided coaches and sport scientists with a deeper understanding of match demands, particularly at the elite level. This has allowed for the development of training programmes that prepare players for the most intense contact and running demands likely to be experienced in competition. At the elite level, rugby league players have well-developed aerobic and anaerobic endurance, muscular strength and power, reactive agility, and speed. Upper- and lower-body strength and aerobic power are associated with a broad range of technical and sport-specific skills, in addition to a lower risk of injury. Significant muscle damage (as estimated from creatine kinase concentrations) and fatigue occurs as a result of match-play; while muscle function and perceptual fatigue generally return to baseline 48 h following competition, increases in plasma concentrations of creatine kinase can last for up to 5 days post-match. Well-developed physical qualities may minimise post-match fatigue and facilitate recovery. Ultimately, the literature highlights that players require a broad range of physical and technical skills developed through specific training. This review evaluates the demands of the modern game, drawing on research that has used GPS technology. These findings highlight that preparing players based on the average demands of competition is likely to leave them underprepared for the most demanding passages of play. As such, coaches should incorporate drills that replicate the most intense repeated high-intensity demands of competition in order to prepare players for the worst-case scenarios expected during match-play.