Biological, Hormonal, and Psychological Parameters in Professional Soccer Players Throughout a Competitive Season

Body mass index: A determinant of distress, depression, self-esteem, and satisfaction with life amongst recreational athletes from random intermittent dynamic type sports

This study aimed to understand the impact of body mass index on distress, depression, self-esteem, and satisfaction with life amongst recreational athletes from random intermittent dynamic type sports. A cross-sectional study design was selected with 440 recreational athletes to conduct this study. The mean age was 20.34 ± 1.33 years, height was 157.27 ± 5.93 cm, weight was 57.31 ± 13.02 kg, and BMI was 25.82 ± 6.64 kg/m². All the athletes voluntarily participated in this study. Psychological distress was measured with the K10 questionnaire; depression was measured with the PHQ-9 self-reported questionnaire. The Rosenberg self-esteem scale measured self-esteem, and Diener's satisfaction with life scale measured satisfaction with life. The data collection was conducted in the classroom setting. It took 12-15 min to complete the survey. The descriptive statistics were calculated, and the ordinal-scale, qualitative variables and frequency distributions for different categories were determined. The Chi-Square (two-tails) test was applied to find the relationship between the variables. The significant level was set at 0.05 level. The result showed that body mass index was significantly related to distress (X ²  = 27.59, p = .001) and life satisfaction (X ²  = 45.14, p = .001). Whereas depression (X ²  = 15.46, p = .148) and self-esteem (X ²  = 12.02, p = .212) showed an insignificant relationship with body mass index among recreational athletes from random intermittent dynamic sports. The study highlighted the health implications of psychological distress, depression, self-esteem, and satisfaction with life with body mass index among recreational athletes from random intermittent dynamic sports. Future studies are needed to understand better the interaction between psychological variables and body mass index level.

Prevalence of low energy availability and associations with seasonal changes in salivary hormones and IgA in elite male Gaelic footballers

PURPOSE

Evidence suggests low energy availability (LEA) is prevalent in elite male Gaelic football (GF) players. Previous research in male and female team sports found LEA may negatively impact endocrine function. The aim of this study was to examine the seasonal variations in energy availability (EA) and its associations with salivary measures in elite male GF players across the competitive season.

METHODS

Energy availability was assessed using field-based methods in conjunction with salivary testosterone (s-T), cortisol (s-C) and immunoglobin A (s-IgA) concentrations at pre-season (PRE), in-season (IN) and post-season (POST).

RESULTS

38% reported LEA at PRE, 33% at IN, and 28.5% at POST. s-C, s-T and s-IgA levels were within normal ranges at PRE, IN and POST. Salivary cortisol declined significantly from PRE to IN, remaining reduced at POST. Salivary testosterone decreased significantly from PRE to IN but was significantly elevated at POST compared to IN. Salivary IgA was significantly greater at POST than IN. No significant associations were found between s-C or s-T and EA at any time point. Pre-season s-IgA exhibited a significant inverse association with PRE EA. Decreased s-IgA flow rate and s-IgA secretion rate were significantly associated with decreased EA at PRE. Reduced carbohydrate (CHO) intake was also associated with decreased s-IgA secretion rate at PRE.

CONCLUSION

This study suggests that LEA is prevalent in elite male GF players, but is not associated with s-C or s-T. However, EA is associated with s-IgA which may impact the immune system. Therefore, education and interventions surrounding the prevalence and associations of EA should be implemented in this population.

Body Composition of Male Professional Soccer Players Using Different Measurement Methods: A Systematic Review and Meta-Analysis

The performance of male soccer players (MSP) depends on multiple factors such as body composition. The physical demands of modern soccer have changed, so the ideal body composition (BC) requirements must be adapted to the present. The aim of this systematic review and meta-analysis was to describe the anthropometric, BC, and somatotype characteristics of professional MSP and to compare the values reported according to the methods and equations used. We systematically searched Embase, PubMed, SPORTDiscus, and Web of Science following the PRISMA statement. Random-effects meta-analysis, a pooled summary of means, and 95% CI (method or equation) were calculated. Random models were used with the restricted maximum likelihood (REML) method. Seventy-four articles were included in the systematic review and seventy-three in the meta-analysis. After comparing the groups according to the assessment method (kinanthropometry, bioimpedance, and densitometry), significant differences were found in height, fat mass in kilograms, fat mass percentage, and fat-free mass in kilograms (p = 0.001; p < 0.0001). Taking into account the equation used to calculate the fat mass percentage and ∑skinfolds, significant differences were observed in the data reported according to groups (p < 0.001). Despite the limitations, this study provides useful information that could help medical technical staff to properly assess the BC of professional MSP, providing a range of guidance values for the different BC.

Acute and chronic effects of physical exercise on IgA and IgG levels and susceptibility to upper respiratory tract infections: a systematic review and meta-analysis

This systematic review and meta-analysis aimed at evaluating acute and chronic effects of physical exercise on IgA and IgG levels, as well as its relationship with the susceptibility to develop upper respiratory tract infections (URTI). This systematic review and meta-analysis was conducted and reported in accordance with PRISMA statement. A systematic search of PubMed, Web of Science, and EMBASE was performed in July 2020. This systematic review and meta-analysis included studies in which participants performed acute exercise or chronic physical training and were subjected to analyses of URTI incidence and concentrations of IgA and IgG. The selected studies for systematic review were divided into the following three groups: (I) trials that evaluated the effects of acute exercise in sedentary subjects, (II) trials that evaluated the effects of acute exercise in athletes/trained individuals, and (III) trials that evaluated the effects of chronic physical training on the incidence of URTI, as well as on the levels of IgA and IgG. Acute exercise increases the IgA levels in trained subjects but does not affect its levels in untrained subjects. Such increase in IgA levels induced by acute exercise is greater in trained individual that performed ultramarathon. On the other hand, chronic physical training reduces IgA levels in both trained and untrained subjects, does not change IgA levels in non-military subjects, besides from not affecting IgG levels. The present systematic review and meta-analysis indicates that acute exercise positively influences IgA levels in trained individuals, being this effect pronounced when a strenuous exercise such as ultramarathon is executed. Chronic physical training, in turn, does not affect IgG levels.

The Immunological and Hormonal Responses to Competitive Match-Play in Elite Soccer Players

This study aimed to examine the salivary immunoglobulin A (s-IgA) and salivary cortisol (s-Cort) responses to competitive matches in elite male soccer players. Data were collected for 19 players (mean ± SD, age: 26 ± 4 years; weight: 80.5 ± 8.1 kg; height: 1.83 ± 0.07 m; body-fat 10.8 ± 0.7%) from a Russian Premier League team throughout a 6-week period during the 2021-2022 season. Physical match loads were measured through an optical tracking system. s-IgA and s-Cort were assessed one day before each match (MD - 1), 60-min before kick-off, 30-min post-match, and 48-h post-match (MD + 2). At 60-min before kick-off, s-IgA values were lower than at MD - 1 (90% CI difference 15.7-71.3 μg/mL). Additionally, compared to 60-min before kick-off, s-IgA was higher at 30-min post-match (90% CI difference 1.8-57.8 μg/mL) and at MD + 2 (90% CI difference 5.4-60.5 μg/mL). At 30-min post-match, s-Cort was higher than at 60-min before kick-off (90% CI difference 4.84-7.86 ng/mL), while on MD + 2 s-Cort was higher than at 60-min before kick-off (90% CI difference 0.76-3.72 ng/mL). Mixed model regressions revealed that longer playing time and total distance covered, and higher number of high-intensity accelerations, involved smaller s-IgA differences between 30-min post-match and 60-min before kick-off, and between 60-min before kick-off and MD + 2. Additionally, greater high-intensity and sprint distances, and a higher number of high-intensity and maximal accelerations, involved smaller s-Cort differences between 60-min before kick-off and MD + 2. In conclusion, the present results demonstrate that using salivary monitoring combined with match load may be a useful tool to monitor individual mucosal immunity and hormonal responses to match-play and the subsequent recovery periods in elite soccer players.

Psychophysiological Stress Markers During Preseason Among Elite Female Soccer Players

ABSTRACT

Botelho, R, Abad, CCC, Spadari, RC, Winckler, C, Garcia, MC, and Guerra, RLF. Psychophysiological stress markers during preseason among elite female soccer players. J Strength Cond Res 36(6): 1648-1654, 2022-This study aimed to investigate changes and correlations between mood states and various physiological stress markers after a 7-week preseason period among elite female soccer players. Twenty-four elite female soccer players participated in this study (26.4 ± 3.7 years). Their internal training load, mood states, day and evening salivary testosterone and cortisol concentrations, blood creatine kinase concentration (CK), and heart rate variability (HRV) were assessed during the first week of preseason (PRE), and again 7 weeks after a systematic training period (END). After the preseason, there were significant increases in subject negative mood scales (p ≤ 0.03; Effect Size [ES] > 0.60), total mood scores (p = 0.01; QI = 100/0/0; ES = 1.32), day and evening testosterone and cortisol concentrations (p ≤ 0.03; ES > 0.54), and CK concentrations (p = 0.01; QI = 100/0/0; ES = 1.54). Correlations were found between cortisol and tension (r = 0.53 and 0.60; p ≤ 0.02), cortisol and confusion (r = 0.75; p = 0.01), and cortisol and the LF/HF index of HRV (r = -0.52; p = 0.04). Mood states (except vigor), salivary testosterone, and cortisol concentrations, as well as CK, showed significant changes after a 7-week systematic training system. The cortisol was the factor most highly related to various mood states (including tension and confusion), and with the HRV indices. Coaches and researchers can use these data to design, monitor, and control soccer training programs, in particular throughout the preseason period.

Selected Immunoendocrine Measures for Monitoring Responses to Training and Match Load in Professional Association Football: A Review of the Evidence

Biomarkers relating to player “stress balance,” immunological (ie, immunoglobulin-A), and hormonal (ie, testosterone and cortisol [T:C]) status are now commonly used in football. This article is our critical review of the scientific literature relating to the response of these measures to player load and their relationships with player health. The commonly reported relationship between immunoglobulin-A and training or match load highlights its sensitivity to changes in psychophysiological stress and the increased risk of compromised mucosal immunity. This is supported by its close relationship with symptoms of upper respiratory tract infection and its association with perceived fatigue in football players. Testosterone and cortisol concentrations and the testosterone–cortisol ratio are sensitive to changes in player load, but the direction of their response is often inconsistent and is likely influenced by player training status and non-sport-related stressors. Some evidence indicates that sustained periods of high training volume can increase resting testosterone and that sustained periods of low and high training intensity can increase resting cortisol, compromising the testosterone–cortisol ratio. These findings are noteworthy, as recent findings indicate interrelationships between testosterone, cortisol, and testosterone:cortisol and perceived measures of fatigue, sleep quality, and muscle soreness in football players. Variability in individual responses suggests the need for a multivariate and individualized approach to player monitoring. Overall, we consider that there is sufficient evidence to support the use of salivary immunoglobulin-A, testosterone, cortisol, and testosterone:cortisol measures as part of a multivariate, individualized player monitoring system in professional football.

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

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.

Upper-Body Resistance Training Following Soccer Match Play: Compatible, Complementary, or Contraindicated?

PURPOSE

During heavily congested schedules, professional soccer players can experience exacerbated fatigue responses, which are thought to contribute to an increased risk of injury. Given that match-induced residual fatigue can last up to 72 hours, many coaches naturally prioritize recovery in the days immediately following match day. While it is intuitive for coaches and training staff to decrease the amount of auxiliary training practices to focus on recovery, prescribing upper-body resistance training on the day after match play has recently emerged as a specific training modality in this context. While these sessions may be implemented to increase training stimulus, there are limited data available regarding the efficacy of such a practice to improve recovery kinetics.

METHODS

In this narrative review, the authors look at the theoretical implications of performing upper-body resistance training on the day after match play on the status of various physiological and psychological systems, including neuromuscular, metabolic, hormonal, perceptual, and immunological recovery.

RESULTS

The available evidence suggests that in most cases this practice, as currently implemented (ie, low volume, low intensity), is unlikely to be complementary (ie, does not accelerate recovery) but is potentially compatible (ie, does not impair recovery).

CONCLUSION

Overall, because the perception of such sessions may be player dependent, their programming requires an individualized approach and should take into account match dynamics (eg, fixture scheduling, playing time, travel).

Biomarkers Correlate With Body Composition and Performance Changes Throughout the Season in Women's Division I Collegiate Soccer Players

The purpose of this study was to evaluate the effects of a competitive soccer season on biomarkers and performance metrics in order to determine the correlation between changes in biomarkers, body composition, and performance outcomes. Twenty-one Division 1 female collegiate soccer players were monitored throughout the 16-week season. Player workload was measured using heart rate and Global Position Satellite systems at all practices and games. Performance testing, including vertical jump, VO_2max, and 3-repetition maximum testing for bench press, squat and deadlift, occurred prior to pre-season and immediately post-season. Blood draws occurred prior to preseason and every 4-weeks thereafter, following a game. Body composition was assessed prior to the start of season (week 0) and weeks 6, 10, 14, and 17 (post-season). Delta area under the curve was calculated for biomarkers and body composition variables to account for seasonal changes adjusted for baseline. Pearson-product moment correlations were used to assess relationships with significance set at p < 0.05. Trends were considered p ≤ 0.10. No significant time main effects were seen for anabolic biomarkers (p > 0.05). Significant time effects were seen for catabolic biomarkers throughout the season (p = 0.001). No changes in body weight, VO_2max, vertical jump, and deadlift occurred. Squat and bench press improved (p = 0.01 and p = 0.02, respectively) with a decline in percent body fat (p = 0.03) and a trend for increased fat free mass (p = 0.09). Additionally, total cortisol (TCORT) negatively correlated with fat free mass (r = −0.48; p = 0.03) and positively correlated with VO_2max (r = 0.47; p = 0.04). A trend was shown for a positive correlation between both TCORT and free cortisol (FCORT) and percent body fat (r = 0.39; r = 0.40; p = 0.08, respectively). IGF-1 and growth hormone positively correlated to deadlift (r = 0.57; P = 0.02 and r = 0.59; p = 0.03), whereas creatine kinase showed a trend for a positive correlation with deadlift (r = 0.49; p = 0.06). IL-6 negatively correlated with bench press (r = −0.53; p = 0.03). These findings support a relationship between biomarkers, performance outcomes, and body composition. Biomarker monitoring may be useful to detect individual player's physiological response to an athletic season and may help provide insights in efforts to optimize performance outcomes.

Upper respiratory symptoms (URS) and salivary responses across a season in youth soccer players: A useful and non-invasive approach associated to URS susceptibility and occurrence in young athletes

This study examined the effect of a competitive season on salivary responses [cortisol (sC), testosterone (sT), Testosterone/Cortisol ratio (sT/C), Immunoglobulin A (sIgA), sIgA secretion rate (srIgA), alpha-amylase (sAA)] and upper respiratory symptoms (URS) occurrence in three teams of male soccer players (Under-15, Under-17 and Under-19 yrs.). Training and competition volumes, salivary biomarkers and URS were determined monthly. No differences were found for monthly training volume between teams. Incidence of URS was higher for the U15 (44.9% of the total cases). Higher sT and srIgA were observed for the U19, lower sC were found for the U17 and sAA showed higher values for the U15 throughout the season. In the U15, significant difference (p = .023) was found for sIgA concentration with higher concentration values in January compared to December (-42.7%; p = .008) and the sT showed seasonal variation (p < .001) with the highest value in January significantly different from October (-40.2%; p = .035), November (-38.5%; p = 0.022) and December (-51.6%; p = .008). The U19 presented an increase in sC in March compared to February (-66.1%, p = .018), sT/C were higher in February compared to March (-58.1%; p = .022) and sAA increased in March compared to September (-20.5%; p = .037). Negative correlations, controlled for age group, were found between URS occurrence and srIgA (r = -0.170, p = .001), sAA (r = -0.179, p = .001) and sT (r = -0.107, p = .047). Monitoring salivary biomarkers provides information on mucosal immunity with impact in URS occurrence. Coaches could manipulate training loads to attenuate the physical stressors imposed on athletes, especially at demanding and stressful periods.

Seasonal Repeated Sprint Ability With Change of Direction Variations in U17 and U20 Elite Brazilian Soccer Players: A Comparative Study

Jorge, G, Garrafoli, MT, and Cal Abad, CC. Seasonal repeated sprint ability with change of direction variations in U17 and U20 elite Brazilian soccer players: a comparative study. J Strength Cond Res 34(5): 1431-1439, 2020-This study aimed to describe seasonal variations of repeated sprint with change-of-direction ability in young elite Brazilian soccer players. The Bangsbo sprint test (BST) was performed by 21 under-17 (U17) (176.9 cm; 68.2 kg) and 22 under-20 (U20) athletes (178.7 cm, 74.4 kg) at the start, middle, and end of the season. The fatigue index (FI) was calculated in seconds and in percentage of decrease (%D) for comparisons. Both age categories showed higher BST performance in the middle and end compared with the start of the season (p ≤ 0.05). The U20 players performed better at the start than the U17 players. The U17 soccer players showed higher FI at the start and in the middle in comparison with the U20 players (p ≤ 0.05). They also showed lower FI at the end of the season in comparison with the start and middle of the season (p ≤ 0.05). The U20 players showed significant reductions in the FI in the middle and at the end in comparison with the start of the season (p ≤ 0.05). Only the U17 soccer players showed lower %D at the end in comparison with the start of the season (p ≤ 0.05). To summarize, both U17 and U20 players performed BST poorly at the start, increased the BST performance until the middle, and maintained the BST performance until the end of the season. A difference in the magnitude of enhancement was observed between U17 and U20 soccer players, which was found to be dependent on the initial values. Finally, the mathematical model to calculate the FI requires caution.

Anabolic-catabolic hormonal responses in youth soccer players during a half-season

This study sought to evaluate the hormonal response (i.e. total testosterone, free testosterone, cortisol, and their ratios TT/C and FT/C) in the under-19 youth soccer team (n = 18) throughout a six-month period. All sport medical examinations were conducted four times: before the beginning of the preparation period (T1), just after preparation period (T2), in the middle of the competitive period (T3), and at the end of the season (T4). The cortisol concentration was decreased at the T3 (-16.9%; p = 0.014), then increased at the T2 (16.8%; p = 0.001) and at the T4 (12.7%; p = 0.062), respectively, compared to the initial value. The analyses for total and free testosterone demonstrated no differences between the measurements. Finally, values of the TT/C and FT/C ratios were increased during the T3 (25%; p = 0.017, 24.4%; p = 0.021) in comparison with the initial measurement and decreased at the T4 (-28.9%; p = 0.001, - 30.8%; p = 0.001) in comparison with the T3. The study results showed that the lowest level of peripheral fatigue was recorded in the T3, which may suggest that a correct selection of training loads does not affect the severity of catabolic processes in youth players.

Monitoring Blood Biomarkers and Training Load Throughout a Collegiate Soccer Season

Huggins, RA, Fortunati, AR, Curtis, RM, Looney, DP, West, CA, Lee, EC, Fragala, MS, Hall, ML, and Casa, DJ. Monitoring blood biomarkers and training load throughout a collegiate soccer season. J Strength Cond Res 33(11): 3065-3077, 2019-This observational study aimed to characterize the responses of a comprehensive panel of biomarkers, observed ranges, training load (TL) metrics, and performance throughout the collegiate soccer season (August-November). Biomarkers (n = 92) were collected before the start of pre-season (PS), in-season weeks (W)1, W4, W8, and W12 in NCAA Division I male soccer players (n = 20, mean ± SD; age = 21 ± 1 years, height = 180 ± 6 cm, body mass = 78.19 ± 6.3 kg, body fat = 12.0 ± 2.6%, VO2max 51.5 ± 5.1 ml·kg·min). Fitness tests were measured at PS, and W12 and TL was monitored daily. Changes in biomarkers and performance were calculated via separate repeated-measures analysis of variance. Despite similar fitness (p > 0.05), endocrine, muscle, inflammatory, and immune markers changed over time (p < 0.05). Total and free testosterone was lower in W1 vs. PS, whereas free cortisol remained unchanged at PS, W1, and W4 (>0.94 mg·dL). Oxygen transport and iron metabolism markers remained unchanged except for HCT (W1 vs. PS) and total iron binding capacity (W8-W12 vs. W1). Hepatic markers albumin, globulin, albumin:globulin, and total protein levels were elevated (p < 0.05) at W12 vs. W1, whereas aspartate aminotransferase and alanine aminotransferase levels were elevated at W1-W12 and W8-W12 vs. PS, respectively. Vitamin E, zinc, selenium, and calcium levels were elevated (p < 0.05) at W12 vs. W1, whereas Vitamin D was decreased (p < 0.05). Fatty acids and cardiovascular markers (omega-3 index, cholesterol:high-density lipoprotein [HDL], docosahexenoic acid, low-density lipoprotein [LDL], direct LDL, non-HDL, ApoB) were reduced at W1 vs. PS (p ≤ 0.05). Immune, lipid, and muscle damage biomarkers were frequently outside clinical reference ranges. Routine biomarker monitoring revealed subclinical and clinical changes, suggesting soccer-specific reference ranges. Biomarker monitoring may augment positive adaptation and reduce injuries from stressors incurred during soccer.

The complex and bidirectional interaction between sex hormones and exercise performance in team sports with emphasis on soccer

A constant topic reported in the lay press is the effect of sex hormones on athletic performance and their abuse by athletes in their effort to enhance their performance or to either boost or sidestep their hard, protracted, and demanding training regimens. However, an issue that it is almost never mentioned is that the athletic training itself affects the endogenous production of androgens and estrogens, while also being affected by them. Among sports, soccer is a particularly demanding activity, soccer players needing to possess high levels of endurance, strength, and both aerobic and anaerobic capacity, with the very great physiological, metabolic, physical, and psychological exertion required of the players being both influenced by sex steroids and, reciprocally, affecting sex steroid levels. This review focuses on the currently available knowledge regarding the complex relationship between athletic training and competition and sex steroid hormone adaptation to the demands of the exercise effort. In the first part of the review, we will examine the effects of endogenous testosterone, estrogen, and adrenal androgens on athletic performance both during training and in competition. In the second part, we will explore the reciprocal effects of exercise on the endogenous sex hormones while briefly discussing the recent data on anabolic androgenic steroid abuse.

Salivary Biomarkers and Training Load During Training and Competition in Paralympic Swimmers

Context: Stress responses in athletes can be attributed to training and competition, where increased physiological and psychological stress may negatively affect performance and recovery. Purpose: To examine the relationship between training load (TL) and salivary biomarkers immunoglobulin A (IgA), alpha-amylase (AA), and cortisol across a 16-wk preparation phase and 10-d competition phase in Paralympic swimmers. Methods: Four Paralympic swimmers provided biweekly saliva samples during 3 training phases—(1) normal training, (2) intensified training, and (3) taper—as well as daily saliva samples in the 10-d Paralympic competition (2016 Paralympic Games). TL was measured using session rating of perceived exertion. Results: Multilevel analysis identified a significant increase in salivary immunoglobulin A (sIgA: 94.98 [27.69] μg·mL−1), salivary alpha-amylase (sAA: 45.78 [19.07] μg·mL−1), and salivary cortisol (7.92 [2.17] nM) during intensified training concurrent with a 38.3% increase in TL. During the taper phase, a 49.5% decrease in TL from the intensified training phase resulted in a decrease in sIgA, sAA, and salivary cortisol; however, all 3 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] nM) despite a continued decrease (77.8%) in TL from the taper phase. Conclusions: Results demonstrate that performance in major competition such as Paralympic games, despite a noticeable reduction in TL, induces a stress response in athletes. Because of the elevated stress response observed, modifications to individual postrace recovery protocols may be required to enable athletes to maximize performance across all 10 d of competition.

Effects of Training and Competition Load on Neuromuscular Recovery, Testosterone, Cortisol, and Match Performance During a Season of Professional Football

Introduction: Training load and other measures potentially related to match performance are routinely monitored in team-sport athletes. The aim of this research was to examine the effect of training load on such measures and on match performance during a season of professional football. Materials and Methods: Training load was measured daily as session duration times perceived exertion in 23 A-League football players. Measures of exponentially weighted cumulative training load were calculated using decay factors representing time constants of 3-28 days. Players performed a countermovement jump for estimation of a measure of neuromuscular recovery (ratio of flight time to contraction time, FT:CT), and provided a saliva sample for measurement of testosterone and cortisol concentrations 1-day prior to each of 34 matches. Match performance was assessed via ratings provided by five coaching and fitness staff on a 5-point Likert scale. Effects of training load on FT:CT, hormone concentrations and match performance were modeled as quadratic predictors and expressed as changes in the outcome measure for a change in the predictor of one within-player standard deviation (1 SD) below and above the mean. Changes in each of five playing positions were assessed using standardization and magnitude-based inference. Results: The largest effects of training were generally observed in the 3- to 14-day windows. Center defenders showed a small reduction in coach rating when 14-day a smoothed load increased from -1 SD to the mean (-0.31, ±0.15; mean, ±90% confidence limits), whereas strikers and wide midfielders displayed a small increase in coach rating when load increased 1 SD above the mean. The effects of training load on FT:CT were mostly unclear or trivial, but effects of training load on hormones included a large increase in cortisol (102, ±58%) and moderate increase in testosterone (24, ±18%) in center defenders when 3-day smoothed training load increased 1 SD above the mean. A 1 SD increase in training load above the mean generally resulted in substantial reductions in testosterone:cortisol ratio. Conclusion: The effects of recent training on match performance and hormones in A-League football players highlight the importance of position-specific monitoring and training.

Mood Effects of Blood Flow Restriction Resistance Exercise Among Basketball Players

This study compared the acute effects of resistance exercise with and without blood flow restriction (BFR) on basketball players' mood states. A total of 11 male basketball players (M age = 19.9, SD = 2.8 years; M height = 180.8, SD = 7.8 cm; M weight = 71.1, SD = 9.1 kg; M body mass index = 22.1, SD = 1.9 kg/m²) were randomly assigned to two experimental conditions: (a) low-load resistance exercise with BFR (LLRE + BFR) and high-load resistance exercise (HLRE) without BFR. We measured mood state with the Brunel Mood Scale before and after each session. There was a significant interaction effect such that there was increased fatigue over time with LLRE + BFR ( p = .001, Δ% = 169.2). Regarding total mood disorder, there were significant pre and postexercise differences between athletes exposed to both the LLRE + BFR and HLRE conditions ( p = .048) and a decharacterization of the iceberg mood profile in the post-training LLRE + BFR condition. LLRE + BFR, compared to HLRE, promoted an acute negative effect on mood state, decharacterization of the iceberg profile, total mood disturbance, and increased participant fatigue, suggesting that this method of strength training should be avoided before sports competitions.

Pallarés J, Pérez-López A, Mora-Rodríguez R, Ortega JF. Hormonal and neuromuscular responses during a singles match in male professional tennis players

We sought to measure the response of cortisol concentrations around a professional tennis match and its association with hydration status and neuromuscular performance. Nine professional male tennis players were tested in a rest day, and 2-week after, during the first match of a professional tournament played in a clay-court. Salivary concentrations of cortisol (SalCC) were measured in a resting day (9:00 am and 8:00 pm), at the match day (9:00 am and 8:00 pm) and immediately before and after the match. Hydration status was assessed before the match (urine specific gravity; USG) while fluid turnover was tracked during the match. Finally, counter movement jump (CMJ) and handgrip isometric strength (HS) were measured before and after the match. SalCC, either in the morning (P = 0.161) and afternoon (P = 0.683) was similar in rest and match days. However, SalCC increased after the match (P = 0.033). Participants started the match hypohydrated (USG = 1.026±0.002) and during the match lost 1.0±0.3% of body weight despite 1.035±0.124 L/h of fluid ingested. CMJ and HS did not change post-match (P = 0.210 and P = 0.881, respectively). Correlations between the elevations in SalCC and dehydration (% BW loss) during the match were significant (r = -0.632; P = 0.034). Professional male tennis players did not show an anticipatory increase in SalCC the day of the match and neither signs of neuromuscular fatigue after it. During the match, the mild dehydration (i.e., <1.5%) was associated with the increases in cortisol levels which suggests that dehydration may be an added stress to be considered.

Monitoring training load and fatigue in soccer players with physiological markers

The quantification and monitoring of training load (TL) has been the topic of many scientific works in the last fifteen years. TL monitoring helps coaches to individually prescribe, follow-up, analyse, adjust and programme training sessions. In particular, the aim of the present review was to provide a critical literature report regarding different physiological markers of TL monitoring, particularly in soccer, as the load is specific to individual sports. Therefore, the interests and limitations of heart rate (HR), HR variability (HRV) and biochemical variables (blood, urinary and hormonal variations) were analysed, with a special focus on daily measures (before, during and after training) and monitoring throughout a whole season. It appears that the most relevant markers were the resting HR before training, HR reserve during training, HRV during rest days, blood lactate, and blood and salivary immunological status in follow-ups throughout the season. Urinary markers indicative of the players' hydration status also deserve attention. However, these objective markers should be considered with a subjective marker of TL such as the rating of perceived exertion to give a more precise quantification of TL and its perception. Future research could be directed towards urinary marker analysis and the analysis of specific markers of TL, which could be related to injury occurrence and to performance during competition.

Redox status alterations during the competitive season in élite soccer players: focus on peripheral leukocyte-derived ROS

It is well known that exercise training can deeply affect redox homeostasis by enhancing antioxidant defenses. However, exhaustive exercise can induce excessive reactive oxygen species (ROS) production, leading to oxidative stress-related tissue injury and impaired muscle contractility. Hence, ROS represent important signaling molecules whose level has to be maintained to preserve normal cellular function, but which can also accumulate in response to repetitive muscle contraction. In fact, low levels of oxidants have been suggested to be essential for muscle contraction. Both aerobic and anaerobic exercise induce ROS production from several sources (mitochondria, NADPH oxidases and xanthine oxidases); however, the exact mechanisms underlying exercise-induced oxidative stress remain undefined. Professional athletes show a high risk for oxidative stress, and consequently muscle injury or decreased performance. Based on this background, we investigated leukocyte redox homeostasis alterations during the soccer season in élite soccer players. Overall blood redox status was investigated in twenty-seven male soccer players from primary division (Italian "Serie A" team) at four critical time points during the soccer season: T0: just before the first team training session; T1: at the beginning of the season; T2: in the middle of the season and T3: at the end of the season. The main markers of muscular damage (CK, myoglobin, LDH), assessed by standard routine methods, are significantly altered at the considered time points (T0 vs T1 P < 0.01). In peripheral leukocyte subpopulations, ROS production shows significant alterations at the considered time points during the soccer season, and strictly and significantly correlates with CK values at every considered time point. Our experimental data indicate that deep redox homeostasis alterations are evident during the soccer season in élite soccer players, and that oxidative stress can be easily monitored, besides using the standard plasma biochemical parameters, by leukocyte ROS production analysis.

Saliva: a reliable sample matrix in bioanalytics

Saliva is gaining increasing attention as a bioanalytical sample matrix. Mostly because of the easy and noninvasive collection, it is not only beneficial in endocrinological and behavioral science, but also in pediatrics. Saliva also has the advantage of being the only body fluid which can be collected even during physical exercise, for example, during sportive activities, and there are physiological characteristics that make it superior to serum/plasma or urine for specific scientific questions. This review provides an insight into the physiology of saliva formation, explaining how certain compounds enter this bodily fluid, and gives advice for collection, storage and analytical methods. Finally, it presents a number of reliable and proven applications for saliva analysis from scientific fields including endocrinology, sports medicine, forensics and immunology.

Fatigue and Recovery in Soccer: Evidence and Challenges

Background:

Soccer presents physiological, metabolic, physical and psychological demands which can deteriorate players’ performance due to fatigue. The high variability in physiological, metabolic, physical and psychological responses also influences the magnitude of exercise-induced muscle damage, with symptoms negatively affecting neuromuscular function during recovery or subsequent training sessions or matches. Consequently, more precise and consistent knowledge is required in this area to optimize training and performance.

Objective:

Therefore, the purpose is to sum-up current evidence on fatigue and recovery in soccer players, to shed light on factors that can affect players’ performance, and to suggest applications for coaches and further research.

Method:

A comprehensive review of the scientific literature on the field was conducted.

Results:

Physical performance decrements during matches have traditionally been associated with physiological fatigue, but the magnitude of the symptoms in soccer players is unclear and depends on several factors. Moreover, the decline in physical performance during a soccer match is related to specific demands of each match. These could explain inter-individual variability in acute fatigue or training recovery processes when comparing players from the same team. Recovery counteracts the effects of fatigue, both peripheral and central, but there is a lack of consensus about the usefulness of tests used to monitor fatigue and recovery kinetics.

Conclusion:

Although fatigue and recovery in soccer has been extensively studied, there are still uncertainties about the underlying mechanisms because they are influenced by physiological and match-related demands.

The Transition Period in Soccer: A Window of Opportunity

The aim of this paper is to describe the physiological changes that occur during the transition period in soccer players. A secondary aim is to address the issue of utilizing the transition period to lay the foundation for the succeeding season. We reviewed published peer-reviewed studies if they met the following three selection criteria: (1) the studied population comprised adult soccer players (aged >18 years), (2) time points of physiological and performance assessments were provided, and (3) appropriate statistics for the calculation of effect sizes were reported. Following two selection phases, 12 scientific publications were considered, involving a total sample of 252 players. The transition period elicits small to moderate negative changes in body composition, a moderate decline in sprint performance with and without changes of direction, and small to moderate decrements in muscle power. Detraining effects are also evident for endurance-related physiological and performance outcomes: large decrements in maximal oxygen consumption V̇O2max) and time to exhaustion, and moderate to very large impairments have been observed in intermittent-running performance. Off-season programs should be characterized by clear training objectives, a low frequency of training sessions, and simple training tools in order to facilitate compliance. The program suggested here may constitute the 'minimum effective dose' to maintain or at least attenuate the decay of endurance- and neuromuscular-related performance parameters, as well as restore an adequate strength profile (reduce muscle strength imbalances). This periodization strategy may improve the ability of players to cope with the elevated training demands of pre-season training and therefore reduce the risk of injury. Moreover, this strategy will favor a more efficient development of other relevant facets of performance during the pre-competition phase (e.g., tactical organization). We contend that the transition period needs to be perceived as a 'window of opportunity' for players to both recover and 'rebuild' for the following season.

Strength training in soccer with a specific focus on highly trained players

Background

Data concerning the physical demands of soccer (e.g., activity pattern) suggest that a high level of performance requires well-developed neuromuscular function (NF). Proficient NF may be relevant to maintain and/or increase players’ short- (intense periods of soccer-specific activity; accelerations, decelerations, and sprinting) and long-term performance during a match and throughout the season.

Objective

This review examines the extent to which distinct modes of strength training improve soccer players’ performance, as well as the effects of concurrent strength and endurance training on the physical capacity of players.

Data sources

A selection of studies was performed in two screening phases. The first phase consisted of identifying articles through a systematic search using relevant databases, including the US National Library of Medicine (PubMed), MEDLINE, and SportDiscus. Several permutations of keywords were utilized (e.g., soccer; strength; power; muscle function), along with the additional scanning of the reference lists of relevant manuscripts. Given the wide range of this review, additional researchers were included. The second phase involved applying six selection criteria to the articles.

Results and conclusions

After the two selection phases, 24 manuscripts involving a total sample of 523 soccer players were considered. Our analysis suggests that professional players need to significantly increase their strength to obtain slight improvements in certain running-based actions (sprint and change of direction speed). Strength training induces greater performance improvements in jump actions than in running-based activities, and these achievements varied according to the motor task [e.g., greater improvements in acceleration (10 m) than in maximal speed (40 m) running movements and in non-squat jump (SJ) than in SSC-based actions (countermovement jump)]. With regard to the strength/power training methods used by soccer players, high-intensity resistance training seems to be more efficient than moderate-intensity resistance training (hypertrophic). From a training frequency perspective, two weekly sessions of strength training are sufficient to increase a player’s force production and muscle power-based actions during pre-season, with one weekly session being adequate to avoid in-season detraining. Nevertheless, to further improve performance during the competitive period, training should incorporate a higher volume of soccer-specific power-based actions that target the neuromuscular system. Combined strength/power training programs involving different movement patterns and an increased focus on soccer-specific power-based actions are preferred over traditional resistance exercises, not only due to their superior efficiency but also due to their ecological value. Strength/power training programs should incorporate a significant number of exercises targeting the efficiency of stretch-shortening-cycle activities and soccer-specific strength-based actions. Manipulation of training surfaces could constitute an important training strategy (e.g., when players are returning from an injury). In addition, given the conditional concurrent nature of the sport, concurrent high-intensity strength and high-intensity endurance training modes (HIT) may enhance a player’s overall performance capacity.

Our analysis suggests that neuromuscular training improves both physiological and physical measures associated with the high-level performance of soccer players.

Electronic supplementary material

The online version of this article (doi:10.1186/s40798-015-0006-z) contains supplementary material, which is available to authorized users.

Markers of biological stress and mucosal immunity during a week leading to competition in adolescent swimmers

In this study we examined changes in the salivary concentrations of immunoglobulin A (sIgA), cortisol (sC), testosterone (sT), and testosterone-to-cortisol ratio (T/C) in 21 competitive swimmers, 11–15 years old, during a week leading to competition as compared to a control (noncompetition) week. No day-to-day changes or significant differences between weeks were observed for sIgA (47.9 ± 4.4 versus 54.9 ± 5.2 μg/mL for control versus competition week, resp.), sC (2.7 ± 0.2 versus 2.5 ± 0.2 ng/mL for control versus competition week, resp.), and T/C ratio (83.4 ± 7.0 versus 77.9 ± 7.7 for control versus competition week, resp.). In contrast, sT was significantly lower during the week of competition (154.5 ± 11.3 pg/mL) as compared to the control week (181.3 ± 11.5 pg/mL) suggesting that the swimmers were in a catabolic state, although this did not have a negative effect on their performance. In conclusion, salivary cortisol did not change between the two weeks, and thus competition stress was relatively low, and mucosal immunity was unaffected in these young athletes prior to competition.

Efeitos do treinamento sobre variaveis psicofisiologicas na pre-temporada de futebol

OBJETIVO: Verificar o efeito da carga de treinamento em variáveis bioquímicas, psicológicas, fisiológicas e hematológicas durante uma pré-temporada em atletas profissionais de futebol. MÉTODOS: Oito jogadores de futebol profissional foram monitorados por 21 dias durante uma pré-temporada e submetidos a quatro avaliações (T1, T2, T3 e T4). As variáveis analisadas foram: concentração de hemoglobina, creatina quinase, questionário POMS e variabilidade da frequência cardíaca no domínio do tempo e da frequência. A carga de treinamento de cada sessão foi quantificada através do método TRIMP. RESULTADOS: A creatina quinase aumentou significativamente (p<0,05) em T2 e T3 com relação a T1, seguindo o comportamento da carga de treinamento. As outras variáveis não apresentaram diferença significativa (p>0,05) e não foram encontradas correlações entre as variáveis. CONCLUSÃO: Parece que a creatina quinase é a variável mais sensível à carga de treinamento do que as outras analisadas. Os valores da variabilidade da frequência cardíaca no domínio da frequência apresentam uma tendência na resposta para mudanças na carga de treinamento.

Biochemical impact of soccer: an analysis of hormonal, muscle damage, and redox markers during the season

This study aimed to analyze changes in performance, muscle function, and stress-related biochemical markers in professional soccer players (n = 14) at 4 timepoints (3 for performance and 4 for stress-related biochemical markers) during the soccer season [Formula: see text] preseason (E1), midseason (E2), end of the season (E3) [Formula: see text] and after the end of the recovery period (E4). Performance in 5- and 30-m sprints, countermovement jump, and agility, and maximal isokinetic knee extension and knee flexion strength were measured (E1 to E3). We observed increased in-season levels of myoglobin (E2 > E1 and E4; p < 0.05), a higher testosterone/cortisol ratio (T/C), and increased levels of creatine kinase (CK), C-reactive protein, superoxide dismutase (SOD), protein sulfhydryls (-SH), and malondialdehyde (E2 and E3 > E1 and E4; p < 0.05). Lower cortisol concentrations (E3 < E1 and E4; p < 0.05) and glutathione reductase activity (E3 < E2 and E4; p < 0.05) were observed at the end of the season. T/C, CK, SOD, -SH, and malondialdehyde decreased during the off-season, and cortisol and glutathione reductase increased (E3 < E4; p < 0.05). Agility increased in E2 and E3 (p < 0.01). Significant correlations were found during the season between hormonal and muscle function parameters (r = 0.56-0.86; p < 0.05). In addition, in E2, significant associations were observed between match-accumulated time (MATE2; minutes played by each player during the competition period), performance, and hormonal and redox parameters (r = 0.456-0.615; p < 0.05). In conclusion, this study shows that soccer players face significant changes in biomarkers of physiologic strain (muscle damage and oxidative stress-related markers) during the season, but values return to normal during the off-season. Additionally, MAT influences physical, hormonal, and oxidative stress-related parameters in professional soccer players.

Muscle damage, endocrine, and immune marker response to a soccer match

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.

DD, Aoki MS. Monitoramento do nível de estresse de atletas da seleção brasileira de basquetebol feminino durante a preparação para a Copa América 2009

OBJETIVOS: 1) investigar a influência da periodização do treinamento de força sobre o perfil dos estados de humor e resposta do cortisol salivar; e 2) verificar a ocorrência do "perfil iceberg" em atletas da seleção brasileira de basquetebol feminino. MÉTODO: O estudo foi conduzido durante o período preparatório para a Copa América 2009, que incluiu três microciclos de treinamento de força com objetivos distintos (resistência muscular, força máxima e potência). As atletas forneceram amostras de saliva e, posteriormente, responderam o questionário short-POMS no início e ao final de cada microciclo. RESULTADOS: Após a ANOVA de medidas repetidas, não foram observadas diferenças para os estados de humor e a concentração de cortisol durante o período investigado. CONCLUSÃO: Os diferentes conteúdos do treinamento de força não afetaram os parâmetros investigados, indicando estabilidade do nível de estresse. O "perfil iceberg" foi verificado em todos os momentos avaliados.

Elaboração de tabelas de percentis através de parâmetros antropométricos, de desempenho, bioquímicos, hematológicos, hormonais e psicológicos em futebolistas profissionais

INTRODUÇÃO: A carência de valores de referência de parâmetros antropométricos, de desempenho, bioquímicos, hematológicos, hormonais e psicológicos é uma limitação importante nas investigações envolvendo futebolistas profissionais. OBJETIVO: Elaborar tabelas de percentis para servirem como referencial de comparação para estudos posteriores. MÉTODOS: Foram utilizados 82 jogadores profissionais de futebol que foram avaliados aproximadamente 30 dias após o início da principal competição disputada pelas equipes. No primeiro dia de avaliação foram coletadas amostras de sangue (25mL) em jejum para determinação dos parâmetros hematológicos (eritrócitos, hemoglobina, hematócrito, volume corpuscular médio - VCM, hemoglobina corpuscular média - HCM, concentração de hemoglobina corpuscular média - CHCM, leucócitos, neutrófilos, eosinófilos, linfócitos, monócitos e plaquetas) e das concentrações de adrenalina, cortisol, creatina quinase, creatinina, noradrenalina, testosterona e ureia. Posteriormente, os atletas foram submetidos à avaliação antropométrica e psicológica. Em seguida, a avaliação da eficiência do sistema anaeróbio lático foi realizada em pista oficial de atletismo. No segundo dia foram realizadas as avaliações para determinação da eficiência do sistema anaeróbio alático e aeróbio. RESULTADOS: A distribuição de percentis (P0, P15, P30, P50, P70, P85 e P100) foi utilizada para apresentação dos resultados. CONCLUSÃO: A elaboração de tabelas de percentis pode ser utilizada como referencial de comparação para investigações posteriores.

Periodization paradigms in the 21st century: evidence-led or tradition-driven?

The planning and organization of athletic training have historically been much discussed and debated in the coaching and sports science literature. Various influential periodization theorists have devised, promoted, and substantiated particular training-planning models based on interpretation of the scientific evidence and individual beliefs and experiences. Superficially, these proposed planning models appear to differ substantially. However, at a deeper level, it can be suggested that such models share a deep-rooted cultural heritage underpinned by a common set of historically pervasive planning beliefs and assumptions. A concern with certain of these formative assumptions is that, although no longer scientifically justifiable, their shaping influence remains deeply embedded. In recent years substantial evidence has emerged demonstrating that training responses vary extensively, depending upon multiple underlying factors. Such findings challenge the appropriateness of applying generic methodologies, founded in overly simplistic rule-based decision making, to the planning problems posed by inherently complex biological systems. The purpose of this review is not to suggest a whole-scale rejection of periodization theories but to promote a refined awareness of their various strengths and weaknesses. Eminent periodization theorists-and their variously proposed periodization models-have contributed substantially to the evolution of training-planning practice. However, there is a logical line of reasoning suggesting an urgent need for periodization theories to be realigned with contemporary elite practice and modern scientific conceptual models. In concluding, it is recommended that increased emphasis be placed on the design and implementation of sensitive and responsive training systems that facilitate the guided emergence of customized context-specific training-planning solutions.

Indicators for high physical strain and overload in elite football players

Laboratory, psychological and performance parameters as possible indicators of physical strain and overload during highly demanding competition phases were evaluated in elite male football players. In two studies with the same objective, periods of high (HE: >270 min during 3 weeks before testing) and low (LE: <270 min) match exposure were compared over the course of an entire season. In study 1 (n=88 players of the first and second German leagues; age: 25.6 ± 4.3 years; body mass index (BMI): 23.2 ± 1.0 kg/m(2) ), blood count, CK, urea, uric acid, CRP and ferritin were determined. In study 2, 19 players of the third German league and the highest under-19 league (age: 19.7 ± 2.8 years; BMI: 22.8 ± 1.7 kg/m(2) ) were screened for individual vertical jump height, maximal velocity and by the Recovery-Stress-Questionnaire for Athletes (REST-Q Sport). The mean differences in exposure times were 180 min (study 1: quartiles: 105, 270 min) and 247 min (study 2: 180, 347 min), respectively. Significant differences were found neither in blood parameters (study 1; P>0.36) nor in physiological testing results or in REST-Q scores (study 2; P>0.20). A 3-week period of high match exposure in elite football players does not affect laboratory, psychometric and performance parameters.

The development and application of an injury prediction model for noncontact, soft-tissue injuries in elite collision sport athletes

Limited information exists on the training dose-response relationship in elite collision sport athletes. In addition, no study has developed an injury prediction model for collision sport athletes. The purpose of this study was to develop an injury prediction model for noncontact, soft-tissue injuries in elite collision sport athletes. Ninety-one professional rugby league players participated in this 4-year prospective study. This study was conducted in 2 phases. Firstly, training load and injury data were prospectively recorded over 2 competitive seasons in elite collision sport athletes. Training load and injury data were modeled using a logistic regression model with a binomial distribution (injury vs. no injury) and logit link function. Secondly, training load and injury data were prospectively recorded over a further 2 competitive seasons in the same cohort of elite collision sport athletes. An injury prediction model based on planned and actual training loads was developed and implemented to determine if noncontact, soft-tissue injuries could be predicted and therefore prevented in elite collision sport athletes. Players were 50-80% likely to sustain a preseason injury within the training load range of 3,000-5,000 units. These training load 'thresholds' were considerably reduced (1,700-3,000 units) in the late-competition phase of the season. A total of 159 noncontact, soft-tissue injuries were sustained over the latter 2 seasons. The percentage of true positive predictions was 62.3% (n = 121), whereas the total number of false positive and false negative predictions was 20 and 18, respectively. Players that exceeded the training load threshold were 70 times more likely to test positive for noncontact, soft-tissue injury, whereas players that did not exceed the training load threshold were injured 1/10 as often. These findings provide information on the training dose-response relationship and a scientific method of monitoring and regulating training load in elite collision sport athletes.

Neuromuscular, endocrine, and perceptual fatigue responses during different length between-match microcycles in professional rugby league players

INTRODUCTION

The purpose of this study was to examine the changes in neuromuscular, perceptual and hormonal measures following professional rugby league matches during different length between-match microcycles.

METHODS

Twelve professional rugby league players from the same team were assessed for changes in countermovement jump (CMJ) performance (flight time and relative power), perceptual responses (fatigue, well-being and muscle soreness) and salivary hormone (testosterone [T] and cortisol [C]) levels during 5, 7 and 9 d between-match training microcycles. All training was prescribed by the club coaches and was monitored using the session-RPE method.

RESULTS

Lower mean daily training load was completed on the 5 d compared with the 7 and 9 d microcycles. CMJ flight time and relative power, perception of fatigue, overall well-being and muscle soreness were significantly reduced in the 48 h following the match in each microcycle (P < .05). Most CMJ variables returned to near baseline values following 4 d in each microcycle. Countermovement jump relative power was lower in the 7 d microcycle in comparison with the 9 d microcycle (P < .05). There was increased fatigue at 48 h in the 7 and 9 d microcycles (P < .05) but had returned to baseline in the 5 d microcycle. Salivary T and C did not change in response to the match.

DISCUSSION

Neuromuscular performance and perception of fatigue are reduced for at least 48 h following a rugby league match but can be recovered to baseline levels within 4 d. These findings show that with appropriate training, it is possible to recover neuromuscular and perceptual measures within 4 d after a rugby league match.

Changes in perceived stress and recovery in overreached young elite soccer players

The aim of this study was to prospectively monitor sport-specific performance and assess the stress-recovery balance in overreached (OR) soccer players and controls. During two competitive seasons, 94 players participated in the study. The stress-recovery balance (RESTQ-Sport) and sport-specific performance (Interval Shuttle Run Test) were assessed monthly. Seven players with performance decrement of at least a month were classified as OR. Stress and recovery measures were assessed between groups (OR vs healthy players) and at different times within the OR group. An unfavorable total recovery score appeared 2 months before diagnosis when compared with the reference values of the healthy group established at the start of the season (P=0.009) and also over the two seasons (P=0.028). The scales Emotional Stress (P=0.044), Physical Recovery (P=0.009), General Well-being (P=0.001) and Sleep Quality (P=0.045) were sensitive to OR compared with the average of the healthy group over the two seasons. Finally, Fatigue and Being in Shape demonstrated the largest changes in stress and recovery within the OR players (effect size=1.14 and 1.50). The longitudinal monitoring of performance and changes in stress and recovery may be useful for the detection of OR in its earliest stage. The information obtained from these tests can be used to optimize individual training and recovery programs.

Perceived tiredness and heart rate variability in relation to overload during a field hockey World Cup

The aim of the study was to examine the utility of perceived tiredness to predict cardiac autonomic response to overload among field hockey players during the 2006 World Cup. The French Society for Sports Medicine (SFMS) questionnaire was administered at the start of the Cup to evaluate perception of tiredness. Autonomic function was assessed nine days later at the semifinal match by time and frequency domain analysis of heart rate variability. An anxiety questionnaire was administered so that the effect of precompetitive anxiety on heart rate variability could be controlled. Results showed a negative correlation between perceived tiredness scores and time domain indexes, and a positive correlation of perceived tiredness scores and the high frequency component ratio (LF/HF ratio) of heart rate variability. Anxiety did not influence the precompetitive cardiac response despite somatic anxiety's correlation with sympathetic response (LF/HF ratio) and tiredness scores. Perceived tiredness predicted the autonomic cardiac response to competitive overload. Thus, the perceived tiredness assessment would be a good early marker of fatigue and overload states during competition.

Effects of cold-water immersion on physical performance between successive matches in high-performance junior male soccer players

In this study, we investigated the effect of water immersion on physical test performance and perception of fatigue/recovery during a 4-day simulated soccer tournament. Twenty high-performance junior male soccer players (age 15.9 +/- 0.6 years) played four matches in 4 days and undertook either cold-water immersion (10 +/- 0.5 degrees C) or thermoneutral water immersion (34 +/- 0.5 degrees C) after each match. Physical performance tests (countermovement jump height, heart rate, and rating of perceived exertion after a standard 5-min run and 12 x 20-m repeated sprint test), intracellular proteins, and inflammatory markers were recorded approximately 90 min before each match and 22 h after the final match. Perceptual measures of recovery (physical, mental, leg soreness, and general fatigue) were recorded 22 h after each match. There were non-significant reductions in countermovement jump height (1.7-7.3%, P = 0.74, eta(2) = 0.34) and repeated sprint ability (1.0-2.1%, P = 0.41, eta(2) = 0.07) over the 4-day tournament with no differences between groups. Post-shuttle run rating of perceived exertion increased over the tournament in both groups (P < 0.001, eta(2) = 0.48), whereas the perceptions of leg soreness (P = 0.004, eta(2) = 0.30) and general fatigue (P = 0.007, eta(2) = 0.12) were lower in the cold-water immersion group than the thermoneutral immersion group over the tournament. Creatine kinase (P = 0.004, eta(2) = 0.26) and lactate dehydrogenase (P < 0.001, eta(2) = 0.40) concentrations increased in both groups but there were no changes over time for any inflammatory markers. These results suggest that immediate post-match cold-water immersion does not affect physical test performance or indices of muscle damage and inflammation but does reduce the perception of general fatigue and leg soreness between matches in tournaments.

Neuromuscular and endocrine responses of elite players during an Australian rules football season

PURPOSE

To examine variations in neuromuscular and hormonal status and their relationship to performance throughout a season of elite Australian Rules Football (ARF).

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Monitoring Changes in Rugby League Players' Perceived Stress and Recovery during Intensified Training

This study assessed whether the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) could be used to monitor changes in perceived stress and recovery during intensified training of rugby league players. 20 semiprofessional rugby league players were divided into two equal groups randomly assigned to complete 6 wk. of Normal Training or Intensified Training, each followed with a 7-day taper. Multistage Fitness Test performance and RESTQ–Sport measures were taken at the beginning, at 2-wk. intervals, and at the end of the training period. Endurance significantly decreased with Intensified Training and returned to baseline levels following the taper, while remaining unchanged in the Normal Training group. The RESTQ–Sport scores with training were positively related to stress subscale scores (Fatigue, Disturbed Breaks, and General Stress) and recovery subscale measures (Success, Physical Recovery, Being in Shape, Self-efficacy, Social Relaxation, General Well-being, and Sleep Quality) decreasing in the Intensified Training group and then normalising following the taper (Stress subscales: Fatigue and General Stress, and Recovery subscales: Physical Recovery and General Well-being). The RESTQ–Sport is a practical psychometric tool for monitoring responses to training in team-sport athletes.

Relationships between training load, injury, and fitness in sub-elite collision sport athletes

The purpose of this study was to develop statistical models that estimate the influence of training load on training injury and physical fitness in collision sport athletes. The incidence of training injuries was studied in 183 rugby league players over two competitive seasons. Participants were assessed for height, body mass, skinfold thickness, vertical jump, 10-m, 20-m and 40-m sprint time, agility, and estimated maximal aerobic power in the off-season, pre-season, mid-season, and end-season. Training load and injury data were summarised into pre-season, early-competition, and late-competition training phases. Individual training load, fitness, and injury data were modelled using a logistic regression model with a binomial distribution and logit link function, while team training load and injury data were modelled using a linear regression model. While physical fitness improved with training, there was no association (P=0.16-0.99) between training load and changes in physical fitness during any of the training phases. However, increases in training load during the early-competition training phase decreased (P= 0.04) agility performance. A relationship (P= 0.01-0.04) was observed between the log of training load and odds of injury during each training phase, resulting in a 1.50 - 2.85 increase in the odds of injury for each arbitrary unit increase in training load. Furthermore, during the pre-season training phase there was a relationship (P= 0.01) between training load and injury incidence within the training load range of 155 and 590 arbitrary units. During the early and late-competition training phases, increases in training load of 175-620 arbitrary units and 145-410 arbitrary units, respectively, resulted in no further increase in injury incidence. These findings demonstrate that increases in training load, particularly during the pre-season training phase, increase the odds of injury in collision sport athletes. However, while increases in training load from 175 to 620 arbitrary units during the early-competition training phase result in no further increase in injury incidence, marked reductions in agility performances can occur. These findings suggest that reductions in training load during the early-competition training phase can reduce the odds of injury without compromising agility performances in collision sport athletes.

Monitoring for overreaching in rugby league players

The aim of this study was to identify indicators of non-functional overreaching (NFOR) in team sport athletes undertaking intensive training loads. Eighteen semi-professional rugby league players were randomly assigned into two pair matched groups. One group completed 6 weeks of normal training (NT) whilst the other group was deliberately overreached through intensified training (IT). Both groups then completed the same 7-day stepwise training load reduction taper. Multistage fitness test (MSFT) performance, VO2 (max), peak aerobic running velocity (V (max)), maximal heart rate, vertical jump, 10-s cycle sprint performance and body mass were measured pre- and post-training period and following the taper. Hormonal, haematological and immunological parameters were also measured pre-training and following weeks 2, 4 and 6 of training and post-taper. MANOVA for repeated measures with contrast analysis indicated that MSFT performance and VO2 (max) were significantly reduced in the IT group over time and condition, indicating that a state of overreaching was attained. However, the only biochemical measure that was significantly different between the IT and NT group was the glutamine to glutamate (Gln/Glu) ratio even though testosterone, testosterone to cortisol (T/C) ratio, plasma glutamate, and CK activity were significantly changed after training in both groups. Positive endurance and power performance changes were observed post-taper in the IT group confirming NFOR. These changes were associated with increases in the T/C ratio and the Gln/Glu ratio and decreases in plasma glutamate and CK activity. These results indicate that although there was no single reliable biochemical marker of NFOR in these athletes, the Gln/Glu ratio and MSFT test may be useful measures for monitoring responses to IT in team sport athletes.