The Competitive Season and Off-Season: Preliminary Research concerning the Sport-Specific Performance, Stress, and Sleep in Elite Male Adolescent Basketball Athletes

d: Through scholastic sports programs, adolescent athletes compete to represent their communities. However, few studies investigate the changes in physiological and mental pro les during varied sport periodization among this population. Therefore, the purpose of this study was to compare the changes in sports performance and stress-related biomarkers between the competitive season (CS) and off-season (OS) in elite adolescent basketball players.

Through scholastic sports programs, adolescent athletes compete to represent their communities. However, few studies investigate the changes in physiological and mental pro les during varied sport periodization among this population. Therefore, the purpose of this study was to compare the changes in sports performance and stress-related biomarkers between the competitive season (CS) and off-season (OS) in elite adolescent basketball players. Method: Nine elite Division I male basketball players (age: 15–18 years. old) participated in this study. Basketball-speci c performance, salivary dehydroepiandrosterone sulfate (DHEA-S)/cortisol levels, mood state, and sleep quality were all accessed during the CS and OS periods. Results: The training load during OS was 26.0% lower than CS (p = 0.001). Muscle mass, aerobic capacity, 10 m sprint, and Abalakov jump (AJ) power during OS were greater than that during CS (+2.2–9.8%, p < 0.05), but planned agility was greater during CS (p = 0.003). The salivary DHEA-S/cortisol was greater during CS than during OS (p = 0.039). The overall mood state and sleep quality did not differ between periods, but the POMS-tension was higher during CS (p = 0.005). Conclusion: The present study demonstrates that muscle mass, aerobic capacity, peak AJ power, and 10 m sprint performance, but not planned agility, were greater during OS compared to CS among elite adolescent basketball players. Furthermore, the stress-related responses re ected by the D/C ratio and mood tension were relatively lower during the OS in these athletes. Thus, this study suggests that coaches and sport science professionals should closely monitor athletes' training states across varied training/competition periods to better react to modifying training or recovery plans. Keywords: dehydroepiandrosterone sulfate (DHEA-S); cortisol; sleep quality; mood state; change of direction 1. Introduction High school student–athletes spend a great deal of time meeting the physical and competition preparation demands of their sport training, which includes physical training, strength training, simulated game practice, and of cial competition throughout the season. At the same time, high school student–athletes also require ongoing physical and skill training during the off-season, and student–athletes also need to cope with their academic workloads. It is well known that participation in

the physical and competition preparation demands of their sport training, which includes physical training, strength training, simulated game practice, and of cial competition throughout the season. At the same time, high school student–athletes also require ongoing physical and skill training during the off-season, and student–athletes also need to cope with their academic workloads. It is well known that participation in intensive sports training and league play Int. J. Environ. Res. Public Health2021,18, 13259.

Int. J. Environ. Res. Public Health2021,18, 13259 2 of 16 affects a variety of physiological parameters in collegiate athletes [1,2], including body composition, muscle strength, and sports performance characteristics. However, there is a lack of studies that have examined the potential changes in these parameters as youth elite basketball players move from the competitive to the off-season. The student–athletes stand out among their peers. The typical student has their basic academic requirements. However, student–athletes not only have the basic academic requirements but the additional training and competition associated with scholastic sports, making this is a particularly challenging and oftentimes stressful balancing act between academics and sports for adolescent athletes. Unlike more studied populations, such as collegiate or professional athletes [3–5], adolescent student–athletes may be undergoing various stages of puberty. Thus, the internal physiological/mental changes associated with puberty are compounded by the external stresses of schoolwork and athletic training and competition [6,7]. Therefore, students need to develop routines to attenuate external stresses while the internal stresses of physiological/mental development continue. Un- fortunately, studies investigating the stress status placed on student–athletes are limited. Although a current systemic review reveals that regular participation in high-intensity in- terval exercise would positively affect cognitive performance and psychological factors [8], there is even less known about the changes in physiological and mental pro les during varied sports periodization in adolescent athletes. Training periodization refers to athletic training that is structured around periods of progressive overload training followed by periods of rest [9]. According to sport-speci c training and competitive performance, athletes' physiological and psychological parame- ters may vary at the different periods during their annual training plan [1,2,10–13]. During the off-season (the end of one season until the next), high school basketball players typi- cally participate in a regular physical training program designed to optimize agility, speed, aerobic, and anaerobic capacity. During the competitive season, strength and conditioning are substituted for team training, simulated games, friendly competition, and athletic recovery. On the other hand, unlike professional athletes, student–athletes may not devote all their time to training periodization. A way to circumvent this, while still reaching peak

in a regular physical training program designed to optimize agility, speed, aerobic, and anaerobic capacity. During the competitive season, strength and conditioning are substituted for team training, simulated games, friendly competition, and athletic recovery. On the other hand, unlike professional athletes, student–athletes may not devote all their time to training periodization. A way to circumvent this, while still reaching peak athletic performance, is to increase training volume and practice time [14]. However, this puts tremendous pressure and stress on student–athletes, both athletically and aca- demically, which may increase the likelihood of illness or injury [11–13] and negatively affect their sleep, recovery, physiological adaptations [15], and academic performance [16]. For example, impaired sleep quality and quantity appear to cause athletes to develop symptoms similar to those of overtraining syndrome; in addition, sleep deprivation affects cognitive function and may lead to slower and less accurate cognitive performance [17]. It has been reported that feelings of tiredness among adolescents oftentimes manifest themselves as dif culty maintaining behaviors that require effort [18] and increase the risk of sport injuries during training/competition [13,19]. Moreover, several recent systemic reviews have revealed that changes in salivary markers (e.g., cortisol, testosterone, im- munoglobulin A, total protein) were observed during long and short training periods in basketball players and that basketball games also induce highly stressful salivary marker changes [20,21]. However, few studies have explored the relationship between changes in stress hormone concentrations, speci c physical performance, and sleep quality among varied training/competition periods in adolescent elite players, particularly in basketball. It is important to closely monitor the changing patterns of these stress-related biomarkers and sleep quality during both competitions and the off-season periods to better prescribe the appropriate training/recovery programs for adolescent basketball athletes. We hypothesized that overall, sports performance, conditioning, and body composi- tion would be better during the competitive season than during the off-season period. As a result of the substantial diversity in training volume and target demands between the competitive and off-season periods, we further hypothesized that sleep quality, fatigue status, and anabolic metabolic stress biomarkers might be affected by the transition from competitive season

sports performance, conditioning, and body composi- tion would be better during the competitive season than during the off-season period. As a result of the substantial diversity in training volume and target demands between the competitive and off-season periods, we further hypothesized that sleep quality, fatigue status, and anabolic metabolic stress biomarkers might be affected by the transition from competitive season to the off-season period in elite high school basketball players. There-

Int. J. Environ. Res. Public Health2021,18, 13259 3 of 16 fore, this study investigated differences in the salivary stress-related hormonal response, mood states, sleep quality, and basketball-speci c physical performance between the com- petitive season (CS) and off-season (OS) periods in elite adolescent basketball players. These ndings may help coaches and sports scientists to better understand the changes in mental and physiological stress states among elite adolescent basketball players. 2. Materials and Methods 2.1. Study Design The purpose of this study was to investigate the periodic changes in sport performance, biomarkers, mood state, and sleep quality in elite high-school basketball athletes. Therefore, the present study design was observational in nature, with no control group. Elite male adolescent Division I high school basketball players were recruited in this study, and our study design is to observe the changes of salivary stress-related hormonal response, mood states, sleep quality, and basketball-speci c physical performance between the competitive season (CS) and off-season (OS) periods in elite adolescent basketball players. This study was approved by the Institutional Review Board (IRB) of National Yang Ming University (protocol#: YM105088F) and performed following the current Declaration of Helsinki. 2.2. Participants Nine elite male adolescent Division I high school basketball players (aged 15–18 years) participated and completed all the tests/questionnaires in this study. Under their coaches' supervision, participants maintained a year-round training schedule. All participants, as well as their guardians/parents, completed an informed consent form prior to the study. The athletes were from teams ranked among the top 8 in the nation at the Division I level. Thus, the athletes that participated in this study were categorized as elite. The anthropometric data of participants are shown in Table. Table 1.Anthropometric data of participants. Variables N = 9 Age (year) 16.1 0.2 Height (cm) 185.9 1.5 Weight (kg) 78.3 1.4 Body fat percentage (%) 14.5 1.0 Muscle mass (kg) 30.1 0.8 2.3. Procedure Basic characteristics, physical performance, and sleep/mood state questionnaires were completed by the participating basketball players and collected during the national competitive season (National High-School Basketball Competition Series, High School Basketball League, Taiwan) and again at the end

16.1 0.2 Height (cm) 185.9 1.5 Weight (kg) 78.3 1.4 Body fat percentage (%) 14.5 1.0 Muscle mass (kg) 30.1 0.8 2.3. Procedure Basic characteristics, physical performance, and sleep/mood state questionnaires were completed by the participating basketball players and collected during the national competitive season (National High-School Basketball Competition Series, High School Basketball League, Taiwan) and again at the end of the off-season recovery period. The training, consisting of basketball-speci c skills and strength/conditioning practice during the periodic training program, was performed under their coaches' supervision during both CS and OS periods (Table). All participants fully complied with the training programs. For the high school Division I basketball team in Taiwan, they were required to continue practicing until summer vacation; thus, the basketball players maintained their regular training during the OS period. For the experimental measurement procedure (study procedure/timeframe, see Figure), physical performance for the competition period was tested within 3 days after the last playoff game was completed (Pre-test), while the OS recovery period was tested 3 months after the national competition (Post-test). To minimize any possible impact from previous training sessions, strenuous exercise and resistance training were avoided for the 2 days leading into the physical performance test during the OS period (Post-test). Both Pre-test and Post-tests included anthropometric measurements, basketball-speci c sports performance, a physical activity log, and mood/sleep quality questionnaires (Figure).

Int. J. Environ. Res. Public Health2021,18, 13259 4 of 16 Table 2.Training programs for the competitive season and off-season. Competitive Season (CS) Off-Season (OS) Total Training Hours per week 20 h 14 h Basic physical training Endurance run, shuttle run, personal practice (dribbling, passing, shutting, cut, crossover, layup, screen) 6 h/week 360 min/session/day 36 sessions/week 6 h/week 360 min/session/day 36 sessions/week Basketball-speci c training Motion offense, defense, one on one, two on two, three on three, team practice, etc. 6 h/week 360 min/session/day 36 sessions/week 3 h/week 360 min/session/day 33 sessions/week Strength and Conditioning Weight/training, agility training, speed training, plyometric training, etc. 3 h/week 360 min/session/day 33 sessions/week 3 h/week 360 min/session/day 33 sessions/week Practice Tournament (Competitions or practice games) 5 h/week (Competition and practice) 2 h/week (Practice games only) Coach rating training intensity 3Physical Challenge (PC) 3Skill-Speci c Challenge (SC) 3PC: 6 scores 3SC: 8 scores 3PC: 7 scores 3SC: 3 scores Note: The Coach rating training intensity (1–10 scale) was rated by the head coach according to the challenge levels of training (scoring level: 1-to-10 scale; e.g., 1: extremely easy; 10: extremely hard).Int. J. Environ. Res. Public Health 2021, 18, x FOR PEER REVIEW 4 of 17 (study procedure/timeframe, see Figure 1), physical performance for the competition period was tested within 3 days after the last playoff game was completed (Pre-test), while the OS recovery period was tested 3 months after the national competition (Post-test). To minimize any possible impact from previous training sessions, strenuous exercise and resistance training were avoided for the 2 days leading into the physical performance test during the OS period (Post-test). Both Pre-test and Post-tests included anthropometric measurements, basketball-specific sports performance, a physical activity log, and mood/sleep quality questionnaires (Figure 1). On the morning of the test day (0700–0830 AM), and following a 10 h fast, salivary samples and anthropometric measurements were collected. Participants also completed the questionnaires. During the afternoon on test day, all basketball-specific physical/sport performance tests were performed. The specific time of day was kept consistent throughout the study (1400–1700 PM). High-intensity exercise training, resistance training, or competitions were not

morning of the test day (0700–0830 AM), and following a 10 h fast, salivary samples and anthropometric measurements were collected. Participants also completed the questionnaires. During the afternoon on test day, all basketball-specific physical/sport performance tests were performed. The specific time of day was kept consistent throughout the study (1400–1700 PM). High-intensity exercise training, resistance training, or competitions were not permitted the two days prior to testing, thus ensuring consistency and minimizing possible confounding factors. The salivary samples were used primarily to analyze levels of the anabolic hormone (DHEA-S) and the stress hormone (cortisol) during the different training/competition periods. Figure 1. Diagram depicting measurement procedures for the competitive season and off-season. Table 2. Training programs for the competitive season and off-season. Competitive Season (CS) Off-Season (OS) Total Training Hours per week 20 h 14 h Basic physical training Endurance run, shuttle run, personal practice (dribbling, passing, shutting, cut, crossover, layup, screen) 6 h/week ✓ 60 min/session/day ✓ 6 sessions/week 6 h/week ✓ 60 min/session/day ✓ 6 sessions/week Basketball-specific training Motion offense, defense, one on one, two on two, three on three, team practice, etc. 6 h/week ✓ 60 min/session/day ✓ 6 sessions/week 3 h/week ✓ 60 min/session/day ✓ 3 sessions/week Figure 1.Diagram depicting measurement procedures for the competitive season and off-season. On the morning of the test day (0700–0830 AM), and following a 10 h fast, salivary samples and anthropometric measurements were collected. Participants also completed the questionnaires. During the afternoon on test day, all basketball-speci c physical/sport performance tests were performed. The speci c time of day was kept consistent throughout the study (1400–1700 PM). High-intensity exercise training, resistance training, or compe- titions were not permitted the two days prior to testing, thus ensuring consistency and minimizing possible confounding factors. The salivary samples were used primarily to

Int. J. Environ. Res. Public Health2021,18, 13259 5 of 16 analyze levels of the anabolic hormone (DHEA-S) and the stress hormone (cortisol) during the different training/competition periods. 2.4. Training and Diet Monitoring From CS to OS periods, the participants were accommodated in student dorms, and the coaches standardized dietary plans and developed a monitored basketball-speci c training program. The dietary plan was referenced to general recommendations (carbohydrate: 55%; protein: 25%; and fat: 20%). For training intensity, the basketball-speci c skills and strength/conditioning practice were performed under their coaches' supervision during both CS and OS periods, and the coach subjective rating training intensity (1–10; low-to-extremely high) is shown in Table. Moreover, the 3-day physical activity recall log (3d-PAL) was also used to record the level of physical activity during the CS and OS periods, as previously described [22]. 2.5. Anthropometric Measurements Two days before anthropometric measurements, all participants were asked to avoid any type of exercise, and the anthropometric measurements were performed after a 10 h overnight fast as previously described [22]. In brief, all participants were instructed to wear the same lightweight shorts and pants between different competition/off-season periods to ensure consistency in front-to-back testing. Bioelectrical impedance (BIA) (HBF- 371, OMRON Inc., Kyoto, Japan) was used to determine body fat percentage and other anthropometric values (weight, body fat rate, fat-free weight, body mass index, etc.). When performing the BIA measurement, each measurement was taken after an overnight fast (10 h), and participants were asked to abstain from drinking water and any other liquids containing alcohol or caffeine for at least 4 h before the BIA assessment. Moreover, to ensure the accuracy of the body composition assessment, the BIA measurement was only taken between 08:00 and 09:00 a.m. 2.6. Basketball Speci c Physical Performance Measurements 2.6.1. Handgrip Strength Dominant handgrip strength was measured using a digital hand-grip dynamometer (TKK 5401; Takei Scienti c Instruments Co, Ltd., Tokyo, Japan). Participants took one attempt, rested for 90 s, and then made a second attempt. The best score was recorded and used for later analyses. 2.6.2. Maximum Vertical Jump Performance The Abalakov jump (AJ)

c Physical Performance Measurements 2.6.1. Handgrip Strength Dominant handgrip strength was measured using a digital hand-grip dynamometer (TKK 5401; Takei Scienti c Instruments Co, Ltd., Tokyo, Japan). Participants took one attempt, rested for 90 s, and then made a second attempt. The best score was recorded and used for later analyses. 2.6.2. Maximum Vertical Jump Performance The Abalakov jump (AJ) test has been widely used to assess lower extremity jump power [23]. The test procedure followed that used in previous reports [24]. Brie y, partici- pants began in an upright posture with feet shoulder-width apart. They were instructed to jump as high as possible, landing with both feet simultaneously. A 90 s rest was al- lowed between attempts. The best attempt was recorded and used for later analysis. The conversion for AJ height to peak vertical jump power value was calculated using the following formula [25]: peak power (Watts) = 61.9 (jump height [cm]) + 36.0 (body mass [kg]) + 1.822. 2.6.3. 10 m/20 m Sprint Performance Ten to 20 m sprint performance was measured using electronic timing gates (TCI Timing System, Brower Timing Systems, UT, USA) [24]. Timing gates were placed at the starting point (0 m; starting line), 10 m, and 20 m. The timing gate recorded 2 sprint session times at 10 m and 20 m, respectively. This set up allowed the researchers to measure speed and acceleration in 20 m. The recorded time (accuracy: 10 msec) was the best time obtained from two attempts, and the participants had a 3 min rest interval between 2 attempts.

Investigates performance and stress changes in elite adolescent basketball players across competitive and off-season periods.