Performance In Adolescent Athletes Research Articles

Evaluation of the Left Ventricular Myocardium Using Layer-Specific Strain Analysis in Adolescent Athletes Performing High-Intensity Interval Training.

High-intensity interval training (HIIT) has been demonstrated to be an efficient way of improving physical performance in adolescent athletes compared to conventional training modalities. The objective of this study was to evaluate the impact of HIIT on the myocardial function of adolescent athletes, specifically focusing on left ventricular (LV) function, using conventional echocardiography and layer-specific strain (LSS) analysis. A total of 19 male adolescent athletes (with mean age of 16.83 ± 1.29years) participating in various football clubs were recruited for this study. During the course of 8weeks, these adolescent male athletes engaged in HIIT program centered around running. Upon completion of HIIT program, a treadmill exercise test was conducted. Subsequently, conventional and LSS echocardiography were conducted to acquire the evaluation of LV myocardial function. Interventricular septum thickness and ventricular mass index were significantly increased post high-intensity interval training (p < 0.005). After the HIIT, the treadmill exercise test demonstrated a significant increase in test duration and metabolic equivalent compared to the pre-training values (p < 0.005). Post high-intensity interval training, LSS analysis revealed significantly improved LV circumferential strain values in the basal and mid-segments of the left ventricle when compared to the pre-training measurements (p < 0.005). The implementation of high-intensity interval training led to an enhancement of circumferential LSS in the LV, indicating a favorable physiological adaptation and improved efficiency of the myocardium.

The Impact of Neck Cooling on Serum Oxidant/Antioxidant Status and HSP70 Levels during High-Intensity Cycling.

Numerous studies have been conducted in an attempt to discover cooling strategies that can be effective in improving exercise performance. However, the mechanism by which neck cooling relieves exercise-induced physiological stress and the optimal cooling temperature are unclear. This study aimed to investigate the effects of neck cooling at different temperatures during high-intensity cycling on body temperature, physiological variables, oxidant/antioxidant status, heat shock protein (HSP) 70 levels, and exercise performance in adolescent athletes. Seven well-trained male adolescent cyclists (age, 17.00 ± 0.76 years; athletic career, 3.86 ± 0.90 years) participated in three exercise trials involving three cooling regimens: control (CON), low-temperature (7 °C) neck cooling (LNC), and mixed-temperature (14 + 20 °C) neck cooling (MNC). The experimental condition used a cross-over design to minimize adaption to the repetitive cycling trials. Cycling consisted of a 20 km warm-up session and a two 2 km race session. Neck cooling at different temperatures was administered for 20 min during each rest period: after the warm-up, after the first 2 km race, and after the second 2 km race. Blood samples were taken to assess serum malondialdehyde (MDA), superoxide dismutase (SOD), and HSP70 levels. In addition, tympanic temperature (Tty), thermal sensation (TS), heart rate (HR), and the saturation of percutaneous oxygen (SpO2) were measured before, immediately after, and 24 h after exercise. As a measure of cycling performance, the race record and speed were measured in the first and second 2 km races. In all trials, Tty, TS, HR, MDA, SOD, and HSP70 levels significantly increased (p < 0.05), and SpO2 levels significantly decreased (p < 0.05). TS significantly decreased 24 h after exercise compared to that immediately after exercise in the LNC and MNC trials (p < 0.05). Serum HSP70 levels were significantly higher 24 h after exercise (0.87 ± 0.10 ng/mL) than immediately after exercise (0.79 ± 0.04 ng/mL) in the CON trial (p < 0.05). Twenty-four hours after exercise, the CON (0.87 ± 0.10 ng/mL) trial showed significantly higher serum HSP70 levels than the LNC (0.73 ± 0.01 ng/mL) trial (p < 0.05). There was no significant difference in cycling race record or speed between the trials (p > 0.05). Our findings suggest that neck cooling can induce a positive effect on thermal perception during recovery after cycling and that neck cooling at a relatively low temperature may be more effective in reducing exercise-induced HSP70 expression.

Contribution of different strength determinants on distinct phases of Olympic rowing performance in adolescent athletes

ABSTRACT Aerobic metabolism dominates Olympic rowing, but research on the relative contribution of strength and power demands is limited. This study aimed to identify the contribution of different strength determinants for distinct phases of rowing ergometer performance. The cross-sectional analysis comprised of 14 rowing athletes (4 female, 10 male, age: 18.8 ± 3.0y, 16.9 ± 2.2y). Measurements included anthropometrics, maximal strength of leg press, trunk extension and flexion, mid-thigh pull (MTP) and handgrip strength, VO2max, and a 2000 m time trial, where peak forces at the start, middle and end phase were assessed. Additionally, rate of force development (RFD) was assessed during the isometric leg press and MTP with intervals of 150, 350 ms and 150, 300 ms, respectively. Stepwise regression models for ergometer performance showed that the start phase was mainly explained by maximal trunk extension and RFD 300 ms of MTP (R2 = 0.91, p < 0.001) and the middle section by VO2max, maximal leg press strength and sitting height (R2 = 0.84, p < 0.001). For the end phase, a best fit was observed for trunk flexion, RFD 350 ms of leg press, body height and sex (R2 = 0.97 p < 0.001), whereas absolute VO2max, trunk flexion and sex explained variance over the entire 2000 m time trial (R2 = 0.98, p < 0.001). It appears that for the high acceleration in the start phase, force transmission through maximum strength for trunk extension is essential, while fast power production along the kinetic chain is also relevant. Additionally, the results support that maximal force complements the reliance on VO2max. Further intervention studies are needed to refine training recommendations.

Differential effects of strength determinants on different phases of olympic rowing performance in adolescent athletes

Background&#x0D; Olympic rowing relies heavily on aerobic metabolism, but the demands on strength and power have not yet been thoroughly investigated (Lawton et al., 2011). As the characteristic pacing strategy compounds an initial start sprint, a sustained middle section and end spurt, the neuromuscular and physiological requirements of the particular phases need to be considered more closely (Garland, 2005; Mikulic, 2011). Therefore, the purpose of this study was to identify strength qualities for distinct phases in rowing performance in adolescent athletes.&#x0D; Methods&#x0D; The cross-sectional analysis of fourteen national competitive rowing athletes (4 female; 10 male) included anthropometrics, isometric and isokinetic leg press, back extension and flexion, isometric mid-thigh pull (MTP) and handgrip strength, VO2max, and a 2000 m time trial, in which peak forces were measured in the start, middle and end phase. The rate of force developments (RFD) were obtained for isometric leg press (150 and 350 ms) and MTP (150 ms and 300 ms). Stepwise regression models were created for ergometer performance in the start, middle and end phases.&#x0D; Results&#x0D; The best fit model for the start phase included isometric back extension and RFD 300 ms of MTP (R2 = 0.912, p &lt; 0.001), while for the middle section it were VO2max, isometric leg press and sitting height (R2 = 0.844, p &lt; 0.001). For the end phase a best fit was observed for isometric back flexion, RFD 350 ms of leg press, body height and sex (R2 = 0.965 p &lt; 0.001), whereas absolute VO2max, isokinetic back flexion and sex explained variance over the entire 2000 m time trial (R2 = 0.975, p &lt; 0.001).&#x0D; Conclusion&#x0D; For the high acceleration at the start, force transmission through maximum back strength seems to be essential, while fast power production along the kinetic chain is also relevant (Baudouin &amp; Hawkins, 2002). In addition to VO2max, produced maximum strength in the leg press explains the importance for the force production of the sustained middle section (Cosgrove et al., 1999). These results indicate that maximal force complements the reliance on VO2max, as well as neuromuscular parameters and maximal force transmission seems to be important for the start phase. Further research through intervention studies is needed to refine training recommendations.&#x0D; References&#x0D; Baudouin, A., &amp; Hawkins, D. (2002). A biomechanical review of factors affecting rowing performance. British Journal of Sports Medicine, 36(6), 396-402. http://dx.doi.org/10.1136/bjsm.36.6.396&#x0D; Cosgrove, M. J., Wilson, J., Watt, D., Grant, S. F. (1999). The relationship between selected physiological variables of rowers and rowing performance as determined by a 2000 m ergometer test. Journal of Sports Sciences, 17(11), 845-852. https://doi.org/10.1080/026404199365407&#x0D; Garland, S. (2005). An analysis of the pacing strategy adopted by elite competitors in 2000 m rowing. British Journal of Sports Medicine, 39(1), 39-42. https://doi.org/10.1136/bjsm.2003.010801&#x0D; Lawton, T. W., Cronin, J. B., &amp; McGuigan, M. R. (2011). Strength testing and training of rowers: A review. Sports Medicine, 41(5), 413-432. https://doi.org/10.2165/11588540-000000000-00000&#x0D; Mikulic, P. (2011). Maturation to elite status: A six-year physiological case study of a world champion rowing crew. European Journal of Applied Physiology, 111(9), 2363-2368. https://doi.org/10.1007/s00421-011-1870-y

A Meta-analysis of the Effects of High-Intensity Interval Training and Small-Sided Games on Sprint Performance in Adolescents

ABSTRACT This study aimed to compare the effects of high-intensity interval training (HIIT) and small-sided games (SSGs) on sprint performance in adolescent athletes in team sports and to provide reference data for training adolescent team-sport athletes. The literature search was performed in PubMed, Web of Science, Scopus, Embase, and SPORTDiscus. Seven eligible articles were selected according to the inclusion and exclusion criteria. HIIT was significantly better than SSGs in the improvement of linear sprint ability (LSA) (standardized mean difference [SMD] = 0.35; p = 0.007). Within-group comparisons showed that both HIIT (SMD = 0.45; p = 0.0007) and SSGs (SMD = 0.27; p = 0.04) effectively improved LSA. There was no significant difference between HIIT and SSGs in the improvement of repeated sprint ability (RSA) (SMD = −0.05; p = 0.77). Within-group comparisons showed no significant differences but a larger effect size of HIIT (SMD = 0.36) than that of SSGs (SMD = 0.17). HIIT is superior to SSGs in improving LSA. Although HIIT is not the best training method for sprint ability, it improves aerobic capacity and speed performance, helping athletes save time and improve training efficiency. HIIT and SSGs have similar training effects on RSA.

Association of the intrinsic foot muscles and plantar fascia with repetitive rebound jumping and jump landing in adolescent athletes: An ultrasound-based study

BackgroundThe characteristics of foot structure in adolescents and adults are different, affecting sports performance and leading to the progression of foot and lower extremity disorders. Research questionThis study aimed to investigate the relationship between the intrinsic foot muscles (IFM) and plantar fascia morphology and the repetitive rebound jumping and jump landing ability in adolescent athletes. MethodsA total of 60 adolescent athletes (35 boys and 25 girls) participated in this study. B-mode ultrasonography was used to obtain images of the IFM and plantar fascia morphology [thickness and cross-sectional area (CSA) of the abductor hallucis (AbH), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and thickness of the plantar fascia]. The repetitive rebound jump performance was evaluated using the Optojump™ system. Participants were instructed to jump five times continuously with one leg, jumping as high as possible with minimal ground contact time. The jump landing was assessed by measuring the dynamic posture stability index (DPSI) using forward one-legged jump landings. ResultsThe thickness and CSA of the AbH and FDB were positively correlated with the jump height and reactive jump index. The DPSI score was significantly correlated with the thickness of the AbH, but not with other IFMs or plantar fascia. In the multiple regression analysis, only the thickness of the FDB was associated with the jump height and reactive jump index, indicating that FDB thickness might facilitate adolescent athletes to jump higher with minimal contact time in repetitive rebounding movements. SignificanceThe IFM (especially FDB) should be focused on when examining sports performance in adolescent athletes.

Contribution of biological maturation and power of upper and lower limbs to crawl swim performance in adolescent athletes

PurposeThere is no consensus in literature data about the influence of biological maturation (BM) on swim performance in young athletes. We analysed the relationship of BM, upper-limb power (ULP), and lower-limb power (LLP) with adolescent athletes’ performance in crawl swim.MethodsThis observational study determined the BM of 16 competitive swimmers (50% males and 50% females; 12.90 ± 0.88 years) by a mathematical model based on bone age and anthropometric measures. ULP and LLP were established by the horizontal launch test and the vertical and countermovement jump tests on a force platform, respectively. Swim performance was evaluated by the average speed in a 100-m crawl sprint.ResultsBM was related to ULP (males: &lt;i&gt;r&lt;/i&gt; = 0.76, &lt;i&gt;p&lt;/i&gt; = 0.001; females: &lt;i&gt;r&lt;/i&gt; = 0.39, &lt;i&gt;p&lt;/i&gt; = 0.02), LLP (males: vertical jump &lt;i&gt;r&lt;/i&gt; = 0.80, &lt;i&gt;p&lt;/i&gt; = 0.02, countermovement jump &lt;i&gt;r&lt;/i&gt; = 0.48, &lt;i&gt;p&lt;/i&gt; = 0.02; females: vertical jump &lt;i&gt;r&lt;/i&gt; = 0.30, &lt;i&gt;p&lt;/i&gt; = 0.04, countermovement jump &lt;i&gt;r&lt;/i&gt; = 0.80, &lt;i&gt;p&lt;/i&gt; = 0.01), and crawl swim performance (males: &lt;i&gt;r&lt;/i&gt; = –0.91, &lt;i&gt;p&lt;/i&gt; = 0.001; females: &lt;i&gt;r&lt;/i&gt; = –0.72, &lt;i&gt;p&lt;/i&gt; = 0.04). BM had a 87% contribution to crawl swim performance in males and a 66% contribution in females. ULP and LLP showed &lt; 50% contribution to crawl swim performance in both females and males.ConclusionsBM was associated with crawl swim performance of adolescent athletes of both sexes. BM exhibited a stronger contribution to crawl swim performance than ULP and LLP in adolescent swimmers at the puberty window.

Influence of Advancing Biological Maturation on Aerobic and Anaerobic Power and on Sport Performance of Junior Rowers: A Longitudinal Study.

Background: Researches are linking Biological Maturation (BM) with the performance of adolescent rowers from both genders. Despite this, there is still not enough information about the influence of BM advancement correlating to sports, aerobic and anaerobic performance in adolescent athletes at the sport modality rowing. Objective: Investigate the influence of Biological Maturation on sports performance and aerobic and anaerobic power in adolescent rowing athletes. Methods: A longitudinal observational study, developed over 3 years, with a sample of 52 adolescents, rowing athletes, of both genders (61% male and 39% female) mean age of 16.0 ± 0.5 years old at the start and 18.4 ± 0.5 years old at the end of the study. Analysis was performed once a year. BM was evaluated through maturational groups generated from Age Peak Height Velocity; maximum aerobic power [VO2Max (ml/kg/min)] and mean anaerobic power (Watts) through the ergometer test (indoor rowing); peak anaerobic power (Watts) through a mathematical model derived from competition time, to determine sports performance analyzed the race time during world championship tryouts. Results: The advancement of BM influenced the reduction of the test time and increase of the mean anaerobic power (Watts) in indoor rowing (η2p > 0.36, p < 0.05), as well as an improvement in performance in sports competition (η2p > 0.35, p < 0.05). However, the advancement of BM did not affect VO2Max (ml/kg/min) in young elite rowing athletes of both sexes (p > 0.05). Conclusion: Advances in biological maturation have been shown to influence the anaerobic and sports performance (reduction of the execution time in 2,000-m) of adolescent rowing athletes of both genders.

Speed, Change of Direction Speed, and Lower Body Power in Young Athletes and Nonathletes According to Maturity Stage

The aim of this study was to establish the role of maturation on the development of physical performance in adolescent athletes and nonathletes. The total studied sample consisted of 231 participants (131 athletes: 72 boys with an average chronological age of 13.53 ± 0.7 and 59 girls with an average chronological age of 11.97 ± 0.8; 100 nonathletes: 47 boys with an average chronological age of 13.73 ± 0.47 and 53 girls with an average chronological age of 11.93 ± 0.33), distributed according to their biological maturity stage (Pre-, Mid-, and Post-Peak Height Velocity [PHV]) and to their gender. The assessment of physical performance was performed using the following tests: Countermovement jump (CMJ), countermovement jump with arm swing (CMJA), squat jump (SJ), five-jump test (5JT), 5 m sprint (5 m), 10 m sprint (10 m), 20 m sprint (20 m), T-test, Zig Zag, and Slalom. The differences in athletes according to biological maturity were identified in all variables except for 5 m (p = 0.33) and Slalom (p = 0.07), while in nonathletes the differences were found in 5JT (p = 0.01), 5 m (p = 0.02), 10 m (p = 0.01), and 20 m (p = 0.01) tests. Additionally, a significant interaction of gender and biological maturity was detected for CMJ (p = 0.03), CMJA (p = 0.01), and Zig Zag (p = 0.05) in athletes. The findings of the current study confirm the importance of maturity status in the assessment of physical performance. As a consequence, a more rational selection of talented athletes could be provided, also enabling the timely development of physical performance in nonathletes as a “window of opportunity”.

Higher levels of inhibitory control are associated with superior neuromuscular performance in adolescent athletes

Higher levels of inhibitory control are associated with superior neuromuscular performance in adolescent athletes

The relevance of whole or segmental body bioelectrical impedance phase angle and physical performance in adolescent athletes

Objective. The physical condition of athletes can be assessed easily and quantitatively using objective indicators. Bioelectrical impedance measures the phase angle (PA), representing hydration and cell function, and is a potential clinical indicator of physical condition. This study aimed to investigate the association between PA and physical performance in adolescent athletes. Approach. Overall, 170 adolescent athletes underwent a sports medical check-up, including body composition measurements and physical performance tests. Whole-body and segmental PAs (arm and leg) were determined based on body composition values. Isometric grip power and knee isokinetic muscle strength were measured as parameters of muscle strength. Counter movement jump height and squat jump height were measured as jump parameters. Associations between PA and each muscle strength or jump parameters were analysed using Pearson product-moment correlation coefficient or Spearman’s rank correlation coefficient. Main results. Whole-body and upper limb PAs were highly correlated with grip power (r = 0.70–0.80). Whole-body and lower limb PAs were correlated with knee isokinetic muscle strength (r = 0.43–0.59). Whole and all segmental PAs were correlated with counter movement jump height (r = 0.46–0.57) and squat jump height (r = 0.42–0.52). Significance. PA can be used to monitor physical condition and sports performance in adolescent athletes. Segmental PAs can help assess the condition of the corresponding body part.

Creatine Supplementation in Children and Adolescents.

Creatine is a popular ergogenic aid among athletic populations with consistent evidence indicating that creatine supplementation also continues to be commonly used among adolescent populations. In addition, the evidence base supporting the therapeutic benefits of creatine supplementation for a plethora of clinical applications in both adults and children continues to grow. Among pediatric populations, a strong rationale exists for creatine to afford therapeutic benefits pertaining to multiple neuromuscular and metabolic disorders, with preliminary evidence for other subsets of clinical populations as well. Despite the strong evidence supporting the efficacy and safety of creatine supplementation among adult populations, less is known as to whether similar physiological benefits extend to children and adolescent populations, and in particular those adolescent populations who are regularly participating in high-intensity exercise training. While limited in scope, studies involving creatine supplementation and exercise performance in adolescent athletes generally report improvements in several ergogenic outcomes with limited evidence of ergolytic properties and consistent reports indicating no adverse events associated with supplementation. The purpose of this article is to summarize the rationale, prevalence of use, performance benefits, clinical applications, and safety of creatine use in children and adolescents.

Heading-Related Slowing by Twenty-Four Hours in Youth Athletes.

Research suggests cumulative effects of repetitive head impacts (RHIs) on brain structure, especially with younger age of first exposure. Further, recent evidence suggests no immediate cognitive changes with increased RHIs but impairments across a sports season. The aim was to examine more closely the short-term time course of behavioral effects of exposure to RHI. Across 2 years, 18 female adolescent soccer players were tested on ProPoint (sensorimotor) and AntiPoint (cognitive) tasks with reaction time (RT) being the main outcome measure. The athletes were tested before and after workout with ball heading (immediate effect), as well as 24 h after workout (24 h effect) throughout two consecutive seasons. The number of headers performed 24 h before workout, during workout, and season average per workout were recorded. The athletes showed a decrease in ProPoint and AntiPoint RTs immediately after a workout, with no change or decrease in RTs with increasing RHIs. However, increasing RHIs during workout increased RTs in both tasks when tested 24 h later. The athletes also showed an increase in AntiPoint RTs with increasing season average RHIs. Our findings show a complex time course of effects of RHIs on sensorimotor and cognitive performance in adolescent athletes, with exposure to RHIs associated with no change or immediate benefits and then deficits by 24 h. Pathophysiological changes associated with exercise and traumatic brain injury can account for the sensorimotor and cognitive performance changes occurring within 24 h after RHIs.

Caffeine improves various aspects of athletic performance in adolescents independent of their 163 C>A CYP1A2 genotypes.

The purpose of this study was to investigate whether variations in 163 C>A CYP1A2 genotypes (rs 762551) (AA, AC, and CC) modify the ergogenic effects of caffeine (CAF) on strength, power, muscular endurance, agility, and endurance in adolescent athletes. One hundred adolescents (age=15±2years) were recruited. Participants ingested CAF (6mg.kg-1 ) or placebo (PLA, 300mg of cellulose) 1hour before performing a sequence of physical tests: handgrip strength, vertical jumps, agility test, sit-ups, push-ups, and the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1). Compared to PLA, CAF enhanced (P<.05) sit-up (CAF=37±9; PLA=35±8 repetitions) and push-up repetitions (CAF=26±11; PLA=24±11 repetitions), and increased distance covered in Yo-Yo IR1 test (CAF=1010.4±378.9; PLA=903.2±325.7m). There was no influence of CAF on handgrip strength (CAF=35.1±8.9; PLA=33.7±8.7 kgf), countermovement jump height (CAF=49.3±12.6; PLA=47.9±13.8cm), spike jump height (CAF=54.2±13.6; PLA=52.9±14.5cm), and time in agility test (CAF=15.8±1.1; PLA=15.9±1.3s, P>.05). When present, the ergogenic effect of CAF was not dependent of genotype. CAF improves muscular endurance and aerobic performance in adolescent athletes, regardless of their 163 C>A CYP1A2 genotype.

In-Season Integrative Neuromuscular Strength Training Improves Performance of Early-Adolescent Soccer Athletes.

Panagoulis, C, Chatzinikolaou, A, Avloniti, A, Leontsini, D, Deli, CK, Draganidis, D, Stampoulis, T, Oikonomou, T, Papanikolaou, K, Rafailakis, L, Kambas, A, Jamurtas, AZ, and Fatouros, IG. In-season integrative neuromuscular strength training improves performance of early-adolescent soccer athletes. J Strength Cond Res 34(2): 516-526, 2020-Although forms of integrative neuromuscular training (INT) are used extensively for injury prevention and treatment, no information exists about its effects on performance of adolescent athletes. We investigated the effects of an in-season INT intervention on performance of early-adolescent players using a 2-group, repeated-measures design. Twenty-eight early adolescents were randomly assigned to a control group (CG, participated only in soccer training, N = 14, 11.4 ± 0.57 years, Tanner stage 2.8 ± 0.6) or an experimental group (INT was added to conventional soccer training, N = 14, 11.2 ± 0.5 years, Tanner stage 2.6 ± 0.5). Integrative neuromuscular training (8 weeks, 3 sessions·wk) aimed to develop core strength, hamstrings eccentric strength, hip/knee musculature, and dynamic stability using body mass exercises, medicine balls, rocker boards, Bosu, stability balls, etc. Ball shooting speed, speed (10, 20-m), change of direction (COD), jumping performance, and strength were measured before and after training. A 2-way repeated-measures ANOVA was used to analyze data. Integrative neuromuscular training improved 10- and 20-m speed (2.52-2.13 and 3.61-3.39 seconds, respectively, p < 0.05), strength (40.1-44.4 kg, p < 0.05), jumping ability (squat jump: 16.3-17.9 cm; countermovement jump: 19.1-20.3 cm, p < 0.05), COD (18.0-17.3 seconds, p < 0.05), and shooting speed (73.8-79.0 km·h, p < 0.05). In the CG, soccer training caused an improvement of smaller magnitude in 10 m and shooting speed (p < 0.05), whereas COD and jumping performance remained unaffected while 20-m speed, COD, and strength deteriorated. These results indicate that an 8-week INT program may induce positive adaptations in performance of early-adolescent soccer players during in-season training, suggesting that INT may be an effective training intervention for this age group.

Development of an Evidence-based Nutritional Intervention Protocol for Adolescent Athletes.

Effective nutritional intervention can help reduce the risk of nutritional problems and improve athletic performance in adolescents. The five A's (assess, advise, agree, assist, and arrange) model is widely used as the theoretical framework for advice on nutrition, smoking, drinking, and physical activity and it recommends that practitioners in primary health care promote behavior change to facilitate positive outcomes. This model has also been useful in understanding the underlying processes of behavior change. This study aimed to develop both a novel evidence-based nutritional intervention protocol, rooted in sound nutritional theory, and a customizable nutritional intervention program to support sustainable healthy eating, enhance nutrient intake, and improve athletic performance in adolescent athletes. In this study, we adapted the 5 A's behavioral change model and motivational interview to develop a theoretical framework to help adolescent athletes change their behavior and achieve their goals. During each step of the 5 A's protocol, a customized nutritional intervention protocol was developed by nutrition experts for each of adolescent athletes. Each plan was developed to improve the eating habits of adolescent athletes through group education and counseling. All nutritional counseling sessions were designed to enable participants to apply nutritional knowledge and practical action plans to their training and competition conditions to enable each of them to achieve individual athletic goals and facilitate self-management. A theoretical and evidence-based nutritional intervention protocol was developed to identify and address obstacles to healthy dietary habits in adolescent athletes. This could be used as the basis for further studies aimed at improving nutrient intake and athletic performance in adolescent athletes.

The Associations of Vitamin D Status with Athletic Performance and Blood-borne Markers in Adolescent Athletes: A Cross-Sectional Study.

The purpose of this study was to examine the associations of vitamin D status with athletic performance and blood-borne markers in adolescent athletes. This cross-sectional study included forty-seven Taekwondo athletes, aged 15–18 years old. Athletic performance was assessed using maximal oxygen consumption (VO2max), Wingate anaerobic power test, vertical jump, agility T-test, lower limb muscle strength, and fatigue resistance. Blood samples were collected to assess serum 25-hydroxyvitamin D [25(OH)D], free-testosterone, cortisol, creatine kinase, and urea. One-way ANOVAs were applied using Bonferroni adjusted alpha levels, which was 0.02 (i.e., 0.05/3). Multiple linear regressions analyses as well as Pearson and partial correlation analyses were used to examine the relationship among 25(OH)D concentration, athletic performance, and blood-borne markers. The participants 25(OH)D concentration were ranged from 16 to 73.25 nmol/L, indicating that 74.5% of the adolescent athletes have vitamin D insufficiency or deficiency. The vitamin D status did not show any significant effects on the performance factors or blood-borne markers. Serum 25(OH)D concentration was positively correlated with mean power output (r = 0.359, p < 0.05) and relative mean power output (r = 0.325, p < 0.05) after adjusting for bone age, height, weight, training experience, lean body mass, and fat mass. However, 25(OH)D concentration was not associated with other performance-related factors and blood-borne markers. In addition, multiple linear regressions analyses revealed that serum 25(OH)D concentration were not significant predictors of athletic performance in adolescent athletes. In conclusion, vitamin D status is weakly correlated with anaerobic capacity; moreover, the underlying mechanisms of how vitamin D influence anaerobic performance is unclear in the present study. Nevertheless, the importance of vitamin D on health benefits should not be underestimated, especially during growth periods.

Effect of COL5A1, GDF5, and PPARA Genes on a Movement Screen and Neuromuscular Performance in Adolescent Team Sport Athletes.

Stastny, P, Lehnert, M, De Ste Croix, M, Petr, M, Svoboda, Z, Maixnerova, E, Varekova, R, Botek, M, Petrek, M, Lenka, K, and Cięszczyk, P. Effect of COL5A1, GDF5, and PPARA genes on a movement screen and neuromuscular performance in adolescent team sport athletes. J Strength Cond Res 33(8): 2057-2065, 2019-The risk of injury increases with adolescents' chronological age and may be related to limited muscle function neuromuscular, genetic, and biomechanical factors. The purpose of this study was to determine whether COL5A1, PPARA, and GDF5 genes are associated with muscle functions and stretch-shortening cycle performance in adolescent athletes. One hundred forty-six youth players (14.4 ± 0.2 years) from various team sports (basketball n = 54, soccer n = 50, handball n = 32) underwent a manual test for muscle function, maturity estimation, functional bend test (FBT), passive straight leg raise (SLR) test, leg stiffness test, test of reactive strength index (RSI), and gene sampling for COL5A1, PPARA, and GDF5. The χ test did not show any differences in allele or genotype frequency between participants before and after peak height velocity. Multivariate analysis of variance showed that COL5A1 rs12722 CT heterozygotes had worse score in FBT (p < 0.001), worse score in SLR (p = 0.003), and lower maturity offset (p = 0.029, only in females) than TT homozygotes. Male GDF5 rs143383 GG homozygotes showed better score in SLR than AA and AG genotypes (p = 0.003), and AA and AG genotypes in both sex had greater RSI than GG homozygotes (p = 0.016). The PPARA rs4253778 CC homozygotes had greater RSI than GG and GC genotypes (p = 0.004). The CT genotype in COL5A1 rs12722 is possible predictor of functional movement disruption in the posterior hip muscle chain, causing shortening in FBT and SLR, which includes hamstrings function. CT genotype in COL5A1 rs12722 should be involved in programs targeting hamstring and posterior hip muscle chain.

Exposure to Serial Post-Concussion Neurocognitive Testing Does not Affect Future “Updated” Baseline Neurocognitive Performance in Adolescent Athletes

Abstract Purpose We investigated a dose response for serial post-concussion neurocognitive testing exposure on updated post-concussion baseline testing performance. Methods Athletes (13-18 yrs) that completed two, valid baseline neurocognitive testing (ImPACT) sessions approximately 1-3 years apart participated in this study. A sub-sample of athletes that sustained a SRC between baseline sessions were categorized into dose-response groups based on the number of serial, post-concussion neurocognitive tests completed following SRC: ONE (n=76), TWO (n=99), and THREE OR MORE (n=111). Athletes that did not sustain a SRC comprised the ZERO group (n=289). Change scores between the first to the second baseline were calculated for the ImPACT Composite and Symptom Scores and compared between the dose-response groups and controls with 5 ANOVAs, with a Bonferroni-corrected p-value of (p&lt;.01). Baseline testing was administered using ImPACT stimuli within the “Baseline” administration, and all post-concussion ImPACT testing was administered using alternate-form associated with that specific post-injury assessment (Post-Injury1, Post-Injury2, etc). Results ANOVAs revealed no effect of number of post-concussion assessments (0, 1, 2, or 3+) on magnitude of the change between first and final baselines, for Verbal Memory (p=.08), Visual Memory (p=.96), Visual Motor Speed (p=.47), Reaction Time (p=.91), or Total Symptom Scores (p=.86). Conclusion Repeated exposure to neurocognitive testing has revealed improvements in Visual Motor Speed among normal controls, across test-retest intervals of 1-month, 1-year, and 2-years. However, in this study, exposure to post-concussion, serial neurocognitive testing had no effect on future performance on post-concussion baseline neurocognitive testing.

The effects of sprint training and the Nordic hamstring exercise on eccentric hamstring strength and sprint performance in adolescent athletes.

Hamstring strain injuries (HSI) are among the most common injuries in field-based team sports with a high-speed running component. The implementation of the Nordic hamstring exercise (NHE) is a well-documented method of improving eccentric hamstring strength to mitigate the risk of HSI occurrence. Sprint training is specific to the injury mechanism and is thought to activate the hamstrings through maximal eccentric contractions. The purpose of this study was to compare the effects of sprint training and the NHE on eccentric hamstring strength and sprint performance. Twenty-eight participants (mean±SD age=16.21±1.34 years; height=1.75m±0.10m; body mass=68.5kg±12.1kg) completed an eccentric hamstring strength assessment and 40m sprint to assess acceleration and maximum speed. Participants were randomly allocated to either a NHE training or sprint training group. Two sessions per week for four-weeks of training was performed with baseline testing procedures repeated in the week following the intervention. Perceptions of soreness were recorded following the warm-up in each training session. Both the NHE (effect size=0.39, P<0.05) and sprint training (effect size=0.29, P<0.05) groups displayed significant gains in eccentric hamstring strength. The NHE group reported trivial improvements in sprint performance, whilst the sprint training group experienced a moderate improvement, specifically in maximum speed (ES=0.83 Moderate). Sprint training also produced greater perceptions of soreness than the NHE following a four-week training intervention, specifically before the start of the last session (P<0.05). These findings indicate that sprint training had a beneficial effect for both eccentric hamstring strength and sprint performance, whilst also producing greater soreness than the NHE following the final training session. It was concluded that a four-week block of maximum speed training may have both an injury prevention and performance enhancement benefit.