Article

Summated Training and Match Load Predictors of Salivary Immunoglobulin-A, Alpha-Amylase, Testosterone, Cortisol and T:C Profile Changes in Elite-Level Professional Football Players: A Longitudinal Analysis

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Abstract

We examined how summated training and match load measures relate to salivary immunological and hormonal profile changes in professional football players. Data were collected from 18 elite-level professional male football players from one English Championship team across a complete 40 wk competitive season. Daily training (micro-technology) and match (computerised tracking) measures of total, high-speed and high-metabolic load running distance and sprint, acceleration, deceleration and sRPE load were converted into exponentially weighted moving average ‘acute’ (7d), ‘chronic’ (28d) and acute:chronic composite load measures. Bi-weekly morning saliva samples were analysed for immunoglobulin-A, alpha-amylase, testosterone, cortisol and testosterone:cortisol. A two-stage data reduction technique using partial least squares modelling and a backward stepwise selection procedure determined the most parsimonious model for each salivary variable. Testosterone had non-linear relationships with chronic total (P=0.015; Cohen’s D: large), high-metabolic load (P=0.001;small) and high-speed (P=0.001;trivial) running distance and linear relationships with chronic sRPE (P=0.002;moderate) and acute:chronic high-speed running distance (P=0.001; trivial). Cortisol had a non-linear relationship with chronic high-speed running distance (P=0.001;trivial). Testosterone:cortisol had non-linear relationships with chronic decelerations (P=0.039;small) and chronic summated acceleration and deceleration load (P=0.039;small). Non-linear relationships typically indicated optimal hormonal responses at squad mean loads. No load variables clearly related to salivary immunoglobulin-A or alpha-amylase changes. We conclude that chronic total and high-intensity load measures relate to hormonal changes and might be useful indicators of player readiness. Acute load variables were not related to immunological or hormonal changes and consequently, should not be used as surrogate measures of player readiness in isolation.

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This study aimed 1)- to test the hypothesis that salivary immunoglobulin A (s-IgA) would vary with training intensity sessions (low intensity [LI] vs. high intensity sessions [HI]) during a traditional training program divided in 4 training periods and 2)- to identify key variables (e.g. GPS data, RPE, training duration) which could affect s-IgA.Saliva samples of 10 elite professional soccer players were collected a)- before the investigation started to establish the baseline level, b)-before and after each 4 training sessions (LI vs. HI). Training intensity was monitored as internal (via heart rate responses and RPE) and external (via GPS) loads.HI sessions were associated with higher external load (GPS) and with higher RPE. Baseline and Pre-Training s-IgA did not differ between the 4 training sessions both for HI and LI. Post-Training s-IgA were not different (in absolute value and in percentage of change) between HI and LI sessions at the first three periods. However, at the fourth period, s-IgA concentration for HI session was significantly lower (p<0.05) than the LI session. The percentage change between s-IgA post-training and s-IgA baseline concentrations differ significantly (p<0.05) between HI and LI training sessions. Significant correlations between s-IgA and training intensity were also noted.HI soccer training sessions might cause a significant decrease in s-IgA values during the post-exercise window as compared with LI sessions. This study encourages coaches to monitor s-IgA in routine particularly during HI training periods to take precautions to avoid upper respiratory tract infection in highly trained soccer players.
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Abstract We compared the match activity profiles of elite footballers from Australian football (AF), rugby league (RL) and soccer (SOC), using identical movement definitions. Ninety-four elite footballers from AF, RL or SOC clubs in Australia participated in this study. Movement data were collected using a 5-Hz global positioning system from matches during the 2008-2011 competitive seasons, including measures of velocity, distance, acceleration and bouts of repeat sprints (RS). Australian footballers covered the greatest relative running distances (129 ± 17 m.min(-1)) compared to RL (97 ± 16 m.min(-1)) and SOC (104 ± 10 m.min(-1)) (effect size [ES]; 1.0-2.8). The relative distance covered (4.92 ± 2.10 m.min(-1) vs. 5.42 ± 2.49 m.min(-1); 0.74 ± 0.78 m.min(-1) vs. 0.97 ± 0.80 m.min(-1)) and the number of high-velocity running (0.4 ± 0.2 no.min(-1) vs. 0.4 ± 0.2 no.min(-1)) and sprint (0.06 ± 0.06 no.min(-1) vs. 0.08 ± 0.07 no.min(-1)) efforts between RL and SOC players were similar (ES; 0.1-0.3). Rugby league players undertook the highest relative number of accelerations (1.10 ± 0.56 no.min(-1)). RS bouts were uncommon for all codes. RL and SOC players perform less running than AF players, possibly due to limited open space as a consequence of field size and code specific rules. While training in football should be code specific, there may be some transference of conditioning drills across codes.
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Objectives: This study examined distances covered at low (1-2 ms(-2)), moderate (2-3 ms(-2)) and high (>3 ms(-2)) acceleration (L(ACC), M(ACC) and H(ACC) respectively) and deceleration (L(DEC), M(DEC), and H(DEC) respectively) during competitive football games. Temporal and transient patterns of acceleration and deceleration were also examined. Design: Observational, repeated measures. Methods: Thirty-six professional male professional footballers were monitored using a 10 Hz non-differential global positioning system (NdGPS). Match data was organised into six 15 min periods (P1: 1-15 min, P2: 16-30 min, P3: 31-45 min, P4: 46-60 min, P5: 61-75 min, and P6: 76-90 min) for analysis of temporal patterns, and into eighteen 5 min periods for analysis of transient patterns. ANOVA with Bonferroni post hoc tests were used to identify significant (p<0.05) differences between periods. Results: Distance covered at L(ACC), M(ACC), H(ACC), L(DEC), M(DEC), and H(DEC) was 424±75 m, 242±25 m, 178±38 m, 365±54 m, 210±23 m and 162±29 m respectively. Between period decrements ranged from 8.0% to 13.2% from P1 to P3, 9.2% to 16.3% from P4 to P6, and from 14.9% to 21.0% from P1 to P6. Following PEAK H(ACC) (148% of mean 5 min H(ACC)), H(ACC) at 5POST was 10.4% lower than mean (p<0.01). Conclusions: Time-dependent reductions in distances covered suggest that acceleration and deceleration capability are acutely compromised during match play. Further, the occurrence of transient fatigue may be supported by the findings that HACC and HDEC performance following PEAK was approximately 10% lower than mean values.
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To examine variations in neuromuscular and hormonal status and their relationship to performance throughout a season of elite Australian Rules Football (ARF). Fifteen elite ARF players performed a single jump (CMJ1) and 5 repeated countermovement jumps (CMJ5), and provided saliva samples for the analysis of cortisol (C) and testosterone (T) before the season commenced (Pre) and during the 22-match season. Magnitudes of effects were reported with the effect size (ES) statistic. Correlations were performed to analyze relationships between assessment variables and match time, training load, and performance. CMJ1Flight time:Contraction time was substantially reduced on 60% of measurement occasions. Magnitudes of change compared with Pre ranged from 1.0+/-7.4% (ES 0.04+/-0.29) to -17.1+/-21.8% (ES -0.77+/-0.81). Cortisol was substantially lower (up to -40+/-14.1%, ES of -2.17+/-0.56) than Pre in all but one comparison. Testosterone response was varied, whereas T:C increased substantially on 70% of occasions, with increases to 92.7+/-27.8% (ES 2.03+/-0.76). CMJ1Flight time:Contraction time (r=.24+/-0.13) and C displayed (r=-0.16+/-0.1) small correlations with performance. The response of CMJ1Flight time:Contraction time suggests periods of neuromuscular fatigue. Change in T:C indicates subjects were unlikely to have been in a catabolic state during the season. Increase in C compared with Pre had a small negative correlation with performance. Both CMJ1Flight time:Contraction time and C may be useful variables for monitoring responses to training and competition in elite ARF athletes.
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This paper discusses the use of saliva analysis as a tool for monitoring steroid, peptide, and immune markers of sports training. Salivary gland physiology, regarding the regulation and stimulation of saliva secretion, as well as methodological issues including saliva collection, storage and analysis are addressed in this paper. The effects of exercise on saliva composition are then considered. Exercise elicits changes in salivary levels of steroid hormones, immunoglobulins, antimicrobial proteins and enzymes. Cortisol, testosterone and dehydroepiandrosterone can be assessed in saliva, providing a non-invasive option to assess the catabolic and anabolic effects of exercise. Validation studies using blood and salivary measures of steroid hormones are addressed in this paper. Effects of acute exercise and training on salivary immunoglobulins (SIgA, SIgM, SIgG) and salivary antimicrobial proteins, including α-amylase, lysozyme and lactoferrin, are also discussed. Analysis of cortisol and testosterone in saliva may help detect the onset of non-functional overreaching and subsequently may help to prevent the development of overtraining syndrome. Assessment of salivary immunoglobulins and antimicrobial proteins has been shown to successfully represent the effects of exercise on mucosal immunity. Increases in SIgA and antimicrobial proteins concentration and/or secretion rate are associated with acute exercise whereas conversely, decreases have been reported in athletes over a training season leaving the athlete susceptible for upper respiratory tract infections. The measurement of physiological biomarkers in whole saliva can provide a significant tool for assessing the immunological and endocrinological status associated with exercise and training.
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An imbalance between the overall strain experienced during exercise training and the athlete's tolerance of such effort may induce overreaching or overtraining syndrome. Overtraining syndrome is characterised by diminished sport-specific physical performance, accelerated fatiguability and subjective symptoms of stress. Overtraining is feared by athletes yet there is a lack of objective parameters suitable for its diagnosis and prevention. In addition to the determination of substrates (e.g. lactate, ammonia and urea) and enzymes (e.g. creatine kinase), the possibilities for monitoring of training by measuring hormonal levels in blood are currently being investigated. Endogenous hormones are essential for physiological reactions and adaptations during physical work and influence the recovery phase after exercise by modulating anabolic and catabolic processes. Testosterone and cortisol are playing a significant role in metabolism of protein as well as carbohydrate metabolism. Both are competitive agonists at the receptor level of muscular cells. The testosterone/cortisol ratio is used as an indication of the anabolic/catabolic balance. This ratio decreases in relation to the intensity and duration of physical exercise, as well as during periods of intense training or repetitive competition, and can be reversed by regenerative measures. Correlations have been noted with the training-induced changes of strength. However, it seems more likely that the testosterone/cortisol ratio indicates the actual physiological strain in training, rather than overtraining syndrome. The sympatho-adrenergic system might be involved in the pathogenesis of overtraining. Overtraining appears as a disturbed autonomic regulation, which in its parasympathicotonic form shows a diminished maximal secretion of catecholamines, combined with an impaired full mobilisation of anaerobic lactic reserves. This is supposed to lead to decreased maximal blood lactate levels and maximal performance. Free plasma adrenaline (epinephrine) and noradrenaline (norepinephrine) may provide additional information for the monitoring of endurance training. While prolonged aerobic exercise conducted at intensities below the individual anaerobic threshold lead to a moderate rise of sympathetic activity, workloads exceeding this threshold are characterised by a disproportionate increase in the levels of catecholamines. In addition, psychological stress during competitive events is characterised by a higher catecholamines to lactate ratio in comparison with training exercise sessions. Thus, the frequency of training sessions with higher anaerobic lactic demands or of competition, should be carefully limited in order to prevent overtraining syndrome. In the state of overtraining syndrome and overreaching, respectively, an intraindividually decreased maximum rise of pituitary hormones (corticotrophin, growth hormone), cortisol and insulin has been found after a standardised exhaustive exercise test performed with an intensity of 10% above the individual anaerobic threshold.(ABSTRACT TRUNCATED AT 400 WORDS)
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The ability to monitor training is critical to the process of quantitating training periodization plans. To date, no method has proven successful in monitoring training during multiple types of exercise. High-intensity exercise training is particularly difficult to quantitate. In this study we evaluate the ability of the session rating of perceived exertion (RPE) method to quantitate training during non-steady state and prolonged exercise compared with an objective standard based on heart rate (HR). In a 2-part design, subjects performed steady state and interval cycle exercise or practiced basketball. Exercise bouts were quantitated using both the session RPE method and an objective HR method. During cycle exercise, the relationship between the exercise score derived using the session RPE method and the HR method was highly consistent, although the absolute score was significantly greater with the session RPE method. During basketball, there was a consistent relationship between the 2 methods of monitoring exercise, although the absolute score was also significantly greater with the session RPE method. Despite using different subjects in the 2 parts of the study, the regression relationships between the session RPE method and the HR method were nearly overlapping, suggesting the broad applicability of this method. We conclude that the session RPE method is a valid method of quantitating exercise training during a wide variety of types of exercise. As such, this technique may hold promise as a mode and intensity-independent method of quantitating exercise training and may provide a tool to allow the quantitative evaluation of training periodization plans.
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As a consequence of the physiological demands experienced during a competitive soccer season, the antagonistic relationship between anabolic and catabolic processes can affect performance. Twenty-five male collegiate soccer players were studied throughout a season (11 weeks) to investigate the effects of long-term training and competition. Subjects were grouped as starters (S; n = 11) and nonstarters (NS; n = 14). Measures of physical performance, body composition, and hormonal concentrations (testosterone [T] and cortisol [C]) were assessed preseason (T1) and 5 times throughout the season (T2-T6). Starters and NS participated in 83.06% and 16.95% of total game time, respectively. Nonstarters had a significant increase (+1.6%) in body fat at T6 compared to T1. Isokinetic strength of the knee extensors (1.05 rad.sec(-1)) significantly decreased in both S (-12%) and NS (-10%; p < or = 0.05) at T6. Significant decrements in sprint speed (+4.3%) and vertical jump (-13.8%) were found at T5 in S only. Though within normal ranges (10.4-41.6 nmol.L(-1)), concentrations of T at T1 were low for both groups, but increased significantly by T6. Concentrations of C were elevated in both groups, with concentrations at the high end of the normal range (normal range 138-635 nmol.L(-1)) at T1 and T4 in NS and T4 in S, with both groups remaining elevated at T6. Data indicate that players entering the season with low circulating concentrations of T and elevated levels of C can experience reductions in performance during a season, with performance decrements exacerbated in starters over nonstarters. Soccer players should therefore have a planned program of conditioning that does not result in an acute overtraining phenomenon prior to preseason (e.g., young players trying to get in shape quickly in the 6 to 8 weeks in the summer prior to reporting for preseason camp). The detrimental effects of inappropriate training do not appear to be unloaded during the season and catabolic activities can predominate.
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The ability to accurately control and monitor internal training load is an important aspect of effective coaching. The aim of this study was to apply in soccer the RPE-based method proposed by Foster et al. to quantify internal training load (session-RPE) and to assess its correlations with various methods used to determine internal training load based on the HR response to exercise. Nineteen young soccer players (mean +/- SD: age 17.6 +/- 0.7 yr, weight 70.2 +/- 4.7 kg, height 178.5 +/- 4.8 cm, body fat 7.5 +/- 2.2%, VO2max, 57.1 +/- 4.0 mL x kg x min) were involved in the study. All subjects performed an incremental treadmill test before and after the training period during which lactate threshold (1.5 mmol x L above baseline) and OBLA (4.0 mmol x L) were determined. The training loads completed during the seven training weeks were determined multiplying the session RPE (CR10-scale) by session duration in minutes. These session-RPE values were correlated with training load measures obtained from three different HR-based methods suggested by Edwards, Banister, and Lucia, respectively. Individual internal loads of 479 training sessions were collected. All individual correlations between various HR-based training load and session-RPE were statistically significant (from r = 0.50 to r = 0.85, P < 0.01). The results of this study show that the session-RPE can be considered a good indicator of global internal load of soccer training. This method does not require particular expensive equipment and can be very useful and practical for coaches and athletic trainer to monitor and control internal load, and to design periodization strategies.
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The following up of some hormonal parameters during the professional soccer training process could be one of the indicators of the training effects. On the other hand, overreaching and overtraining as an opposite adaptation of supercompensation could be detected by following up some hormonal changes. The aim of this study is to evaluate the changes in some hormonal parameters in professional soccer players during a half-season competition. We included 30 professional soccer players from a soccer club of our National Soccer League in this study. All sport medical examinations were conducted tree times: before the preparation phase, before the competition phase (after previous phase) and after finishing the competition phase. There were significant differences in all evaluated hormones between three phases of soccer training process, including significant decrease in T/C of more than 30% at the end of the competition phase (phase III). The decrease in muscle mass after the preparation phase and the increase in fat mass at the end of competition phase were insignificant. The hormonal changes indicated that some indices could indicate overreaching and overtraining at the end of professional soccer competition season. Although insignificant, the decrease in muscle mass after the preparation phase and the increase in fat mass at the end of competition phase were undesirable effects for us (Tab. 4, Fig. 2, Ref. 19).
Article
In part 2 of this clinical commentary, we highlight the conceptual and methodologic pitfalls evident in current training-load-injury research. These limitations make these studies unsuitable for determining how to use new metrics such as acute workload, chronic workload, and their ratio for reducing injury risk. The main overarching concerns are the lack of a conceptual framework and reference models that do not allow for appropriate interpretation of the results to define a causal structure. The lack of any conceptual framework also gives investigators too many degrees of freedom, which can dramatically increase the risk of false discoveries and confirmation bias by forcing the interpretation of results toward common beliefs and accepted training principles. Specifically, we underline methodologic concerns relating to (1) measure of exposures, (2) pitfalls of using ratios, (3) training-load measures, (4) time windows, (5) discretization and reference category, (6) injury definitions, (7) unclear analyses, (8) sample size and generalizability, (9) missing data, and (10) standards and quality of reporting. Given the pitfalls of previous studies, we need to return to our practices before this research influx began, when practitioners relied on traditional training principles (eg, overload progression) and adjusted training loads based on athletes' responses. Training-load measures cannot tell us whether the variations are increasing or decreasing the injury risk; we recommend that practitioners still rely on their expert knowledge and experience.
Article
This investigation examined the effect of prior workload on high-intensity football match performance. Player load variables were recorded using a global positioning system and converted into composite variables: rolling season accumulated load (AL), exponentially weighted moving average acute, chronic and acute:chronic workload ratio (A:C). Match-play high-intensity performance-per-minute: accelerations (ACC), sprints, high-speed running (HSR) and high metabolic load (HMLd) distances; and situational and contextual variables were recorded for all games. Partial least squares modelling, and backward stepwise selection determined the most parsimonious model for each performance variable. Quadratic relationships of small to moderate effect sizes were identified for sprint AL and sprint performance, HSR AL and HSR performance, acute HMLd and HMLd performance, acute sprint load and ACC performance and A:C sprint load and ACC performance. Match performance was typically greatest between the mean and +1SD. High chronic HMLd, and combined acceleration and deceleration (ACC+DEC) load exerted small beneficial effects on HMLd and HSR performance, whereas high acute load exerted trivial to moderate negative effects. High sprint A:C exerted a small beneficial effect on sprint performance and playing position exerted small effects on HSR and HMLd performance. Prior workload has trivial to moderate effects on high-intensity match performance in professional players.
Article
Exercise is a stressor that induces various psychophysiological responses, which mediate cellular adaptations in many organ systems. To maximize this adaptive response, coaches and scientists need to control the stress applied to the athlete at the individual level. To achieve this, precise control and manipulation of the training load are required. In 2003, the authors introduced a theoretical framework to define and conceptualize the measurable constructs of the training process. They described training load as having 2 measurable components: internal and external load. The aim of this commentary is to extend, clarify, and refine both the theoretical framework and the definitions of internal and external training load to avoid misinterpretation of this concept.
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Inactive runners or sedentary active individuals?
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Purpose: Stress responses in athletes can be attributed to training and also competition, where increased physiological and psychological stress may negatively impact on performance and recovery. The aim of this study was to examine the relationship between training load and salivary biomarkers IgA, alpha-amylase (AA) and cortisol across a 16-week preparation phase and 10-day competition phase in Paralympic swimmers. Methods: Four Paralympic swimmers provided bi-weekly saliva samples during three training phases - 1) normal training, 2) intensified training and 3) taper as well as daily saliva samples in the 10 day Paralympic competition (2016 Paralympic Games). Training load (TL) was measured using session-RPE. Results: Multi-level analysis identified a significant increase in sIgA (94.98 (27.69) μg.ml-1), sAA (45.78 (19.07) μg.ml-1) and salivary cortisol (7.92 (2.17) ng.ml) during intensified training concurrent with a 38.3% increase in TL. During taper phase, a 49.5% decrease in TL from the intensified training phase resulted in decrease in sIgA, sAA and salivary cortisol; however, all three remained higher than baseline levels. A further significant increase was observed during competition in sIgA (168.69(24.19) μg.ml-1), sAA (35.86(16.67) μg.ml-1) and salivary cortisol (10.49(1.89) ng.ml) despite a continued decrease (77.8%) in TL from taper phase. Conclusions: Results demonstrate performance in major competition such as Paralympic Games despite a noticeable reduction in TL induces a stress response in athletes. Due to elevated stress response observed, modifications to individual post-race recovery protocols may be required to enable athletes to maximise performance across all ten days of competition.
Article
The purpose of this study was to a) determine the heart rate variability (HRV) and saliva markers of immunity (salivary immunoglobulin A; sIgA) and stress (salivary alpha-amylase; sAA) responses to chronic training in elite swimmers with a disability; and b) identify the relationships between HRV, sIgA, sAA and training volume. Eight members of a high performance Paralympic swimming program were monitored for their weekly resting HRV, sIgA and sAA levels in the 14 weeks leading up to a major international competition. The 14 week training program included aerobic, anaerobic, power and speed, and taper training phases, while also incorporating two swimming step tests and two swimming competitions. Specific time (root mean square of the successive differences; RMSSD) and frequency (high frequency normalized units [HFnu]) domain measures, along with non-linear indices (standard deviation of instantaneous RR variability; SD1 and short term fractal scaling exponent; α1) of HRV were used for all analyses with effects examined using magnitude-based inferences. Relationships between HRV and saliva markers were identified by Spearman rank rho (ρ) correlation coefficients. Compared with week 1, SD1 was very likely lower (96/4/0, ES = -2.21), while sAA was very likely elevated (100/0/0, ES = 2.32) at the beginning of week 7 for all athletes. The training program did not alter HRV or saliva whereas competition did. There were also no apparent differences observed for HRV, sIgA and sAA between each of the training phases during the 14 week swimming program. Correlations were observed between sAA and SD1 (ρ = -0.212, p
Article
The aim of this study was to examine the validity and reliability of a novel immunoassay, developed to assess salivary Immunoglobulin A (s-IgA). Validity and reliability of the Individual Profiling Lateral Flow Device (IPRO LFD) for s-IgA concentrations ([s-IgA]) was assessed in males (n = 12) and females (n =13) who were involved in recreational activities. Reliability of the IPRO LFD method was assessed by comparing [s-IgA] of two saliva samples collected concurrently, while validity was assessed by comparing with an enzyme-linked immunosorbent assay (ELISA) method. The IPRO LFD had a strong positive correlation (r = 0.93, p < 0.001), with no difference in [s-IgA] compared with the ELISA. The IPRO LFD was considered reliable (ICC r = 0.89, p < 0.001 and CV = 9.40 %) for measures of [s-IgA]. We concluded that the IPRO LFD method may be a substitute to the ELISA method for measurements of [s-IgA].
Article
To (1) examine the pre- and post-match salivary Immunoglobulin A concentration ([s-IgA]) response to AFL match-play, and (2) investigate the acute and cumulative influence of player workload and post-match [s-IgA] following repeated participation in AFL match-play. Eleven elite AFL athletes (21.8 ± 2.4 years, 186.9 ± 7.9 cm, 87.4 ± 7.5 kg) were monitored throughout three matches, during the pre-season which were separated by seven days. Saliva samples were collected across each AFL matches at 24 hours (h) and 1 h pre-match, and 1 h, 12 h, 36 h, and 60 h post-match, to determine [s-IgA]. Global Positioning Systems (GPS) with integrated tri-axial accelerometers were used to determine total player workload during match-play. Hypothesis testing was conducted for time dependant changes in [s-IgA] and player load using a repeated measures ANOVA. Player load during match three (1266 ± 124.6 AU) was significantly (p < 0.01) greater than match one (1096 ± 115.1 AU) and match two (1082 ± 90.4 AU). Across match three; [s-IgA] was significantly (p < 0.01) suppressed at two post-match measures (12 h and 36 h) compared to pre-match measures (24 h and 1 h) which coincided with significantly (p < 0.01) elevated player load. Our findings indicate that an increase in player load during AFL pre-season match-play resulted in compromised post-match mucosal immunological function. Longitudinal assessment of AFL match player load, and mucosal immunological function across the first 60 h of recovery may augment monitoring and preparedness strategies for athletes.
Conference Paper
ABSTRACT Introduction The measurement of a number of salivary biomarkers has become common place in Premier League Soccer teams, in an attempt to monitor responses to training, competition, lifestyle factors and stress. The purpose of this paper was to analyse markers of mucosal immunity through the second half of a competitive season in a cohort of Premier League Academy players. Methods A total of 256 saliva samples were taken during routine monitoring of a cohort 16 players in the under-18 age group of an English Premier League club Academy. Morning saliva samples were collected weekly over a period of 17 weeks between the christmas break and the end of the competitive season. The IgA concentration of the samples was determined using an IPRO Point of Care device and the remaining sample was sent to a remote laboratory for the subsequent determination of IgG and alpha-amylase (sAA) by ELISA. On any occasion that players perceived upper respiratory symptoms (URS) a WURSS questionnaire was completed and extra saliva samples (115) taken each day until symptoms had ceased. Results IgA, IgG and sAA were highly variable between subjects (with CV 57.6, 81.4 and 59.5% respectively) and within subjects (48.5, 65.9, and 46.4%) through the 17 week period. Weekly group mean (±SD) IgA ranged from 114.1 (57.5) to 318.4 (176) μg/ml, IgG from 27.4 (23.7) to 61.7 ( 30.5) μg/ml and sAA from 191.9 (100.7) to 370.6 (203) μg/ml, but no significant differences were seen due to the high individual variability. During the 17 week study period 26 incidences of URS were reported by 15 of the players and were monitored using WURSS and subsequent saliva testing. A drop in IgA by more than 40% from individual healthy mean values, within two weeks of each URS episode, was seen in 14 of the 26 episodes. A drop in IgA/sAA ratio by more than 40% of individual healthy mean values, within two weeks of each URS episode, was seen in 19 of the 26 episodes. However, using the same individualised criteria for IgA and IgA/sAA ratio there were 28 and 38 samples, respectively, where such drops did not lead to URS, with several such occurences seen within the same individuals. In cases where URS were reported, subsequent IgA during perceived symptoms was seen to rise 40% above individual healthy mean levels in 15 of the 26 episodes. Conclusion Salivary markers of mucosal immunity, particularly IgA and sAA when expressed as percentages of healthy baseline norms have good potential for predicting self-reported URS in this cohort of elite under 18 soccer players. Rather than remain suppressed through symptoms, these markers were often then seen to rise by more than 40%. Creation of individual profiles of such salivary markers seems warranted for purposes of monitoring.
Article
We quantified the acceleration and high-velocity running of elite Australian soccer players. We hypothesised that high-intensity activity would be underestimated when excluding acceleration during match analysis given its high metabolic demand and occurrence at low velocities. Player movements were observed from 29 players (forwards and central and wide defenders and midfielders) during domestic Australian competition using 5-Hz global positioning system. Effort occurrence were determined for high-velocity running, sprinting and maximal accelerations. The commencement and final velocity of maximal accelerations were also identified. Players undertook an 8~fold greater number of maximal accelerations than sprints per game (65±21 vs. 8±5). Of maximal accelerations ~98% commenced from a starting velocity lower than what would be considered high-velocity running while ~85% did not cross the high-velocity running threshold. The number of efforts performed in all categories were position dependent (P<0.001). Wide defenders performed more maximal accelerations (P<0.006) and central defenders and midfielders performed less sprints compared to all other positions (P<0.02). Maximal accelerations are frequently undertaken during a match often occurring at low velocities. Excluding maximal accelerations in match analysis research may underestimate the amount of high-intensity movements undertaken. Additionally positional differences in high-intensity movements should be accounted for when developing specific conditioning drills.
Article
Thorpe, R and Sunderland, C. Muscle damage, endocrine, and immune marker response to a soccer match. J Strength Cond Res 26(10): 2783-2790, 2012-This study represents the first time that muscle damage, endocrine, and immune markers have been measured, together with activity profile, during a competitive soccer match. Seven semiprofessional soccer players participated in a competitive league match. Blood and saliva samples were obtained 1 hour before kick off and immediately postmatch. Global positioning system equipment was used to measure heart rate and activity profile data throughout the match. Percentage increase in creatine kinase (CK) and myoglobin (MYO) concentrations was correlated with the number of sprints performed during the match (r = 0.88, p = 0.019; r = 0.75, p = 0.047, respectively). Creatine kinase increased by 84% (p = 0.17) from prematch to postmatch, whereas MYO increased by 238% (p = 0.05). Players performed 39 ± 18 sprints during the course of the match. Cortisol increased by 78% (p = 0.103), whereas testosterone increased significantly by 44% (p = 0.004). No differences were seen from prematch to postmatch in the testosterone to cortisol ratio, immunoglobulin (Ig) A, IgM, or IgG. Sprinting is correlated with changes in CK and MYO and may therefore be associated with muscle damage in semiprofessional soccer players.
Article
Statistical guidelines and expert statements are now available to assist in the analysis and reporting of studies in some biomedical disciplines. We present here a more progressive resource for sample-based studies, meta-analyses, and case studies in sports medicine and exercise science. We offer forthright advice on the following controversial or novel issues: using precision of estimation for inferences about population effects in preference to null-hypothesis testing, which is inadequate for assessing clinical or practical importance; justifying sample size via acceptable precision or confidence for clinical decisions rather than via adequate power for statistical significance; showing SD rather than SEM, to better communicate the magnitude of differences in means and nonuniformity of error; avoiding purely nonparametric analyses, which cannot provide inferences about magnitude and are unnecessary; using regression statistics in validity studies, in preference to the impractical and biased limits of agreement; making greater use of qualitative methods to enrich sample-based quantitative projects; and seeking ethics approval for public access to the depersonalized raw data of a study, to address the need for more scrutiny of research and better meta-analyses. Advice on less contentious issues includes the following: using covariates in linear models to adjust for confounders, to account for individual differences, and to identify potential mechanisms of an effect; using log transformation to deal with nonuniformity of effects and error; identifying and deleting outliers; presenting descriptive, effect, and inferential statistics in appropriate formats; and contending with bias arising from problems with sampling, assignment, blinding, measurement error, and researchers' prejudices. This article should advance the field by stimulating debate, promoting innovative approaches, and serving as a useful checklist for authors, reviewers, and editors.
Article
We examined changes in the haematological, metabolic, immunological, hormonal, and psychological fields using selected variables in 20 professional soccer players. over the course of a competitive season. The team performance was assessed by computing the winning percentage. A symptom checklist was used to assess the severity of upper respiratory tract infections. A high-intensity training programme induced a significant increase in cortisol and uric acid concentrations. Despite lower glutamine concentrations than the normal range throughout the study, infection occurred only in two of the soccer players. Moreover, the levels of immunological factors IgA, IgG, and IgM, and the haematological parameters were unaltered. Subsequent decreased performance coincided with changes in specific mood states of the team. Our results show some alterations on the metabolic, hormonal, and psychological variables over the five fields studied, suggesting that combined psychological and physiological changes during training are of primary interest to monitor the training stress in relation to performance in team sport.
Article
Accurate determination of speed is important in many studies of human and animal locomotion. Some global positioning system (GPS) receivers can data log instantaneous speed. The speed accuracy of these systems is, however, unclear with manufacturers reporting velocity accuracies of 0.1-0.2 ms(-1). This study set out to trial non-differential GPS as a means of determining speed under real-life conditions. A bicycle was ridden around a running track and a custom-made bicycle speedometer was calibrated. Additional experiments were performed around circular tracks of known circumference and along a straight road. Instantaneous speed was determined simultaneously by the custom speedometer and a data logging helmet-mounted GPS receiver. GPS speed was compared to speedometer speed. The effect on speed accuracy of satellite number; changing satellite geometry, achieved through shielding the GPS antenna; speed; horizontal dilution of precision and cyclist position on a straight or a bend, was evaluated. The relative contribution of each variable to overall speed accuracy was determined by ANOVA. The speed determined by the GPS receiver was within 0.2 ms(-1) of the true speed measured for 45% of the values with a further 19% lying within 0.4 ms(-1) (n = 5060). The accuracy of speed determination was preserved even when the positional data were degraded due to poor satellite number or geometry. GPS data loggers are therefore accurate for the determination of speed over-ground in biomechanical and energetic studies performed on relatively straight courses. Errors increase on circular paths, especially those with small radii of curvature, due to a tendency to underestimate speed.
How much is too much?
  • T Soligard
  • M Schwellnus
  • J M Alonso
Soligard T, Schwellnus M, Alonso JM, et al. How much is too much? (Part 1) 540
International Olympic Committee consensus statement on load in sport and risk 541 of injury
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Football: Current Practice and Perceptions
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