Overtraining may affect the majority of elite athletes at least once in their career, the pathophysiology is, however, not clearly understood. This study investigated dietary patterns in adolescent sprinters by comparing athletes who maladapted to prior training with those who adapted well, to identify underlying triggers of overtraining. Food diaries were completed by participants during different training phases over 26 weeks. Participants were classified as non-athletes (NA, n = 13), maladapted (MA, n = 12) and adapted (AA, n = 20) athletes. Total energy (p < 0.001), protein (p = 0.009) and carbohydrate (p < 0001) intakes changed across the different training phases. Compared to AA, MA showed a decrease in total energy (p = 0.009) and carbohydrate (p < 0.001) intakes throughout the season. Similarly, compared to NA, MA showed a decrease in total energy (p = 0.005) and carbohydrate (p < 0.001) intake across the season. A combination of total energy and carbohydrate intakes, sleep quality, and training load/volume were assessed in a logistic regression model, energy intake [OR (95%CI): 4.7 (1.4, 9.3), p < 0.001], carbohydrate intake [OR (95%CI): 14.6 (10.0, 21.4), p < 0.001], and sleep quality [OR (95%CI): 2.8 (1.9, 4.8), p = 0.014] explained overtraining beyond the training load/volume in sprinters. Reduced total energy intake, carbohydrate intake and sleep quality are likely triggers of overtraining beyond intensive training. Caloric and macronutrient periodization as a part of training could prevent maladaptation to training in adolescent sprinters.

This study aimed to investigate the influence of testosterone (T) and cortisol (C) on Skeletal Muscle Markers (SMM) at each phase of a track and field macrocycle. On a secondary basis, we also sought to determine whether C or T moderates the relationship between SMM and performance. Twenty-eighth (28) elite junior sprint athletes (15.48 ±1.89 years), and 13 non-athletic (16.15 ±1.51 years), age and gender-matched controls participated in this study. Isometric muscle strength (MS) and muscle thickness (MTH) were considered SMM. Salivary C and T levels, MS and MTH were collected between 2:30 and 3:00 p.m. before training sessions, twice during the preparatory phase [baseline (T1) and midway into the specific preparation period (T2)] and twice in competition phase [midway point of pre-competition (T3) and midway of the major competition period (T4)]. Performance data were collected during the competition phase only. No significant improvements in SMM were observed. T and T/C ratio significantly increased (p<0.05) across the season, while C levels increased relative to baseline only. While T levels did not significantly predict SMM at any phase, C levels significantly explained (p<0.05) a 60% and 74% variance in MTH and performance respectively. However, neither C nor T significantly moderated the relationship between SMM and performance. These findings suggest that raising T levels across a season may be more indicative of a response to training load, rather than a reflection of skeletal muscle adaptation. While training-induced C, which was demonstrated to have a greater influence on SMM is more sensitive to muscle function changes and performance compared to testosterone.

BACKGROUND: Although the effect of dehydration on performance is widely studied, limited data concerning the levels of risk training types pose to hydration status exists. This study sought to determine: 1) pretraining hydration status in adolescent sprinters relative to non-athletes; 2) changes in hydration markers across a season of adolescent sprinters relative to non-athletes; and 3) if frequency of training type explains unique variance in hydration.METHODS: Hydration (via pretraining urine osmolality [UOsm] and thirst perception [TP]), daily water intake (TWI) (via 24-h food/fluid diaries) and frequencies of resistance, endurance and sprint training types (via training regime questionnaires) were assessed in 26 sprinters (age: 15.6±1.9 years) and 26 non-athletes (age: 16.0±1.6 years), during 4 mesocycles (general [T1] and specific [T2] preparation; precompetitive [T3] and peaking [T4] phases), over 26 weeks.RESULTS: Most athletes (62-81%) and non-athletes (73-92%) were underhydrated (UOsm>700 mOsmol/kg) pretraining across the season, despite a low TP. There were significant time (P=0.042) and group (P=0.006) effects, and a main group by time interaction for UOsm (P=0.006) but not TP across the season, after controlling for TWI. Greater UOsm (in mOsmol/kg) were observed during T1 (906.3±250.1) and T2 (934.5±257.0) compared to T3 (852.1±268.8) and T4 (854.2±218.8). There was no significant change across the season for non-athletes. Frequencies of endurance training were positively associated with UOsm and explained unique variances across the season (R2 range from 7%-16%).CONCLUSIONS: Underhydration is high in the adolescent population. Training type may be related to the variations in hydration throughout a season, which may help to inform hydration practices of sprint athletes.

The aims of this study were to investigate the feasibility of an experiential learning initiative led by minority exercise science undergraduates and to observe the adaptations after a 10-week high-intensity functional training (HIFT) program in 34 underrepresented, hypertensive, and overweight/obese professional firefighters (PFF; age: 36.8 ± 11.0 years, body weight: 97.3 ± 21.5 kg, height: 181.7 ± 6.6 cm; BMI: 29.2 ± 4.9 kg/m2). Data were analyzed for muscular strength and endurance, cardiorespiratory endurance, body composition, agility, flexibility, and readiness for change. The PFFs trained two to three times weekly during their work shifts at vigorous intensity for 40 min. Their resting diastolic blood pressure and resting heart rate significantly decreased. Improvements in agility, muscular strength, and readiness for change were observed. This HIFT experiential learning initiative was feasible and beneficial and improved the PFFs’ health and physical fitness with limited resources. Accredited programs in exercise science participating in low-cost initiatives may aid in mitigating public service workers’ compensation and injury rates to better respond to occupational demands.

Although sleep disturbance is a common complaint in overtrained athletes, the role of sleep in the overtraining process is not clear. This study aimed (i) to compare sleep efficiency/quantity at the start of a competition phase in elite adolescent sprinters who adapted to prior training with that in those who maladapt and (ii) to examine the influence of prior training, fatigue, and sleep on performance through a moderated mediation model. Fatigue (via Profile of Mood State) and internal training load (via session rating of perceived exertion and duration of training as volume) were measured in 20 sprinters (mean age: 15.9 ± 1.7 years) across 4 mesocycles (baseline (T1); preparatory (T2); precompetitive (T3); and competitive (T4) phases), over 26 weeks. Performances were assessed during the competitive period (T3, T4), while sleep was monitored (via actigraphy) for a week during T4. It was inferred that sprinters who had increasingly greater fatigue and concomitant decrements in performance (35%) were maladapted to training and the remaining sprinters who improved fatigue and performance (65%) were adapted to training. Sleep efficiency (91 ± 3% vs. 82 ± 3%, p < 0.001) and quantity (425 ± 33 min vs. 394 ± 20 min, p < 0.001) at the start of T4 were significantly greater in sprinters who adapted. Moreover, higher prior training volume (mean of T1 to T3 training volume) was associated with lower sleep efficiency at the start of T4 (R 2 = 0.55, p < 0.001) which was associated with poorer performance (R 2 = 0.82, p < 0.001). Fatigue moderated the indirect effect of prior training volume on performance through its moderation of the effect of sleep efficiency on performance (R 2 = 0.89, p < 0.001). Impaired sleep as a result of greater prior training volume may be related to performance decrements through fatigue. Athletes should improve sleep during periods of higher training volume to reduce fatigue for better adaptation to training.

•Salivary cortisol and trait anxiety correlated negatively with junior track and field athletic performance.•Salivary cortisol explains a unique variance in youth’s sport performance.•Salivary cortisol mediates the anxiety performance relationship in junior athletes.

PURPOSE: : To characterize and evaluate the body composition and muscle characteristics profile of junior track and field athletes in the athletic preseason and postseason. METHODS: The study included 55 junior athletes. Age, height and weight ranged from 12-19 yrs,157-191 cm, and 42.88-100.88kg, respectively. Body composition and muscle characteristics were measured using ultrasound technology. The two-compartmental model which divides the body into fat mass (FM) and fat free mass (FFM) was used for the analysis of body composition. Muscle cross sectional area (mCSA), muscle thickness (MT) and echo intensity (EI) were used to analyze muscle characteristics. Performance (∫P) was quantified using the IAAF scoring system, where each time/distance, was assigned a score and ∫P calculated. Athletes were categorized into two groups, based on ∫P: (Group A- increase in performance, Group B- decrease in performance in terms of time or distance). RESULTS: Group B athletes had higher mean values for body %fat in the preseason. However, there was no significant change in %fat or regional fat thickness between preseason and postseason, irrespective of performance group. Though not significant, (p>0.05) %fat and waist circumference increased in group B athletes, but decreased in group A athletes. Significant correlations were found between change in muscle cross sectional area in the waist (p<0.05, r= 0.63) and thigh (p<0.05, r= 0.87), with performance in all athletes CONCLUSIONS: Significant differences in body composition parameters between group A and group B athletes at preseason, highlights the importance of maintaining optimal body composition in the offseason. Changes in muscle characteristics in preseason and post-season may influence athletic performance more than changes in body composition over the same period.

Understanding determinants associated with dropout from sport is important for talent development. This study aimed (i) to determine dropout rates for Jamaican track and field athletes and (ii) to examine contextual factors (i.e., relative age effect and place of development) as potential determinants of junior athletes progressing to the senior level. A sample of 1552 track and field athletes (mean age 18.57±0.41 years) who were finalists at the national high school (junior) championships in Jamaica between 2000 and 2017 were evaluated from the Jamaica Athletics Administrative Association database. The database provided birth date, school attendance and performance results. A retrospective analysis was completed to investigate the relationship between junior and senior successes and dropout rates. Chi-square analyses were conducted to examine the distribution of birth date quartiles based on the selection year. Using the Jamaican census information, the population size of regions where participants attended school were categorized and used as a proxy for athletes' place of development. Results showed that the majority of the participants did not progress to senior levels (81%). The relative age effect was evident for athletes who progressed to the senior level but was not evident for athletes who did not progress. There was a bias towards participants who attended school in regions with a population size between 5000-29 999. This study illuminates some of the contextual factors that may influence the likelihood of progressing from junior to senior levels which may help to inform talent identification, selection and development in the sport of track and field.

Exercise and competition function as stress factors and may result in dsyregulation in the neuroendocrine and cardiovascular systems. PURPOSE: The intent of the study was to evaluate neuroendocrine and cardiovascular response using salivary cortisol and heart rate/ blood pressure respectively in junior track and field athletes across a season. METHOD: Fifty-One Jamaican junior level track and field athletes (26 females, 25 males) participated in the study. Data was collected throughout the athletic season over two main periods: (1) a preparation period and (2) a competition period which was further subdivided into two stages: development game stage and major game stage. Athletes delivered a saliva sample prior to bedtime (8 pm - 10 pm) during each phase of the season. Resting blood pressure and heart rate were monitored throughout the season. Data collected during the preparation and competition periods were compared using Friedman’s test and Wilcoxon signed-rank test. RESULTS: There were significant changes in salivary cortisol across the season p<0.05. The concentration of cortisol increased during the development game stage (42%), then further increased in the major game stage (53%). With regard to cardiovascular response, there were significant differences in heart rate across the season p <0.05. However, there was no significant change in blood pressure across the season in the athletes. CONCLUSION: Overall, there was an increase in cortisol across the season. This could possibly be due to the accumulation of stress factors over the competitive season which might be due to improper training regimens. Resting heart rate and blood pressure may not be good indicators of stress in athletes.

Psychophysiological stress appears to be a significant parameter in youth competitive sport participation. Primarily because adolescent athletes are faced with the extreme pressurized scenarios, youth competitive sport offers. Numerous youth sport performers have not learned adaptive coping skills to ameliorate the effects of an inherently stressful environment. This oftentimes results in the elicitation of stress responses, which when prolonged cause an overproduction of hormones which can have severe negative psychological and physiological implications. The implications include a disruption of metabolism and cognitive functioning, as well as cell production in the immune system which may influence the course of chronic diseases and disorders. A detailed understanding of the molecular and genetic events underlying the association of stressors with the psychophysiological pathways is crucial for the design of psychological interventions tailored specifically for athletes so as to improve well-being and performance.

Changes in body composition parameters can be used as a mean of tracking an athlete’s health. Athletic performance relative to fat mass should be evaluated as an increase may be detrimental to physical activities by increasing energy demands and decreasing performance. Body composition, is an important indicator of nutritional status, water homeostasis and the specific adaptations to different physical training regimens. Similarly, assessment of the thigh muscles can provide adequate information on functionality and injury vulnerability. Knowledge garnered from biometric analysis using ultrasound and bio-impedance analysis technology, may be used to gauge the health status of future elite athletes. Assessing the body composition and muscle characteristics of young athletes, allow for early detection of weak areas that may negatively affect the performance of these athletes in the future. In addition, knowledge of how these parameters vary with performance provides an athlete with data that may be used to optimize performance.