The role of growth and maturation during adolescence on team-selection and short-term sports participation.

BACKGROUND: During adolescence, deselection from sport occurs during team try-outs when month of birth, stage of growth and maturation may influence selection. AIM: The purpose of this study was to identify differences in growth and maturity related factors between those selected and deselected in youth sports teams and identify short-term associations with continued participation. SUBJECTS AND METHODS: Eight hundred and seventy participants, aged 11-17 years, were recruited from six sports try-outs in Saskatchewan, Canada: baseball, basketball, football, hockey, soccer and volleyball. Two hundred and forty-four of the initial 870 (28%) returned for follow-up at 36 months. Chronological (years from birth), biological (years from age at peak height velocity (APHV)) and relative (month of birth as it relates to the selection band) ages were calculated from measures of date of birth, date of test, height, sitting height and weight. Parental heights were measured or recalled and participant's adult height predicted. Reference standards were used to calculate z-scores. Sports participation was self-reported at try-outs and at 36-month follow-up. RESULTS: There was an over-representation of players across all sports born in the first and second quartiles of the selection bands (p < 0.05), whether they were selected or deselected. z-scores for predicted adult height ranged from 0.1 (1.1) to 1.8 (1.2) and were significantly different between sports (p < 0.05). Height and APHV differences (p < 0.05) were found between selected and deselected male participants. In females only weight differed between selected and deselected female hockey players (p < 0.05); no further differences were found between selected and deselected female participants. Four per cent of deselected athletes exited sports participation and 68% of deselected athletes remained in the same sport at 36 months, compared with 84% of selected athletes who remained in the same sport. CONCLUSIONS: It was found that youth who attended sports team's try-outs were more likely to be born early in the selection year, be tall for their age, and in some sports early maturers. The majority of both the selected and deselected participants continued to participate in sport 36 months after try-outs, with the majority continuing to participate in their try-out sport.

Neutral Effect of Increased Dairy Product Intake, as Part of a Lifestyle Modification Program, on Cardiometabolic Health in Adolescent Girls With Overweight/Obesity: A Secondary Analysis From a Randomized Controlled Trial.

Background: The presence of obesity and some cardiometabolic disease risk factors in childhood and adolescence track into adulthood. Intake of dairy products has been shown to be inversely related to adiposity and cardiometabolic variables in youth. However, limited research has examined cardiometabolic disease risk factors following increased dairy product consumption as part of a lifestyle modification intervention in youth with overweight/obesity. This secondary analysis aimed to determine whether 12 weeks of increased dairy consumption, as part of a lifestyle modification program, affects cardiometabolic variables in adolescent females (range: 10-18 years) with overweight/obesity (BMI > 85th centile). Methods: Participants were randomized into two groups: higher dairy intake (RDa; four servings/day [to reflect previous Canada's Food Guide recommendations]; n = 23) or low dairy intake (LDa; 0-2 servings/day; n = 23). Both RDa and LDa participated in a 12-week, eucaloric, lifestyle modification intervention consisting of exercise training, and nutritional counseling. Adiposity (percent body fat [%BF]), dietary intake, and measures of cardiometabolic health were measured pre- and post-intervention. Results: There were no significant changes over time within groups or differences over time between groups for triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), TC/HDL ratio, low-density lipoprotein cholesterol (LDL), glucose, insulin, homeostatic model assessment of insulin resistance, adiponectin, and tumor necrosis factor alpha (TNF-α) (main effects of time and interactions, p > 0.05). Leptin decreased over the 12-week lifestyle intervention in both groups (main effect of time, p = 0.02). After combining the groups (n = 46), significant correlations were found between change in %BF and change in some cardiometabolic variables (HDL [r = -0.40], TC/HDL ratio [r = 0.42], LDL [r = 0.36], and TNF-α [r = 0.35], p < 0.05). After controlling for change in dairy product intake, the correlations were unchanged. Conclusion: Our findings demonstrate that increased dairy product consumption, as part of a lifestyle modification, weight management intervention, had a neutral effect on cardiometabolic disease risk factors in adolescent females with overweight/obesity. Change in dairy product intake did not influence the relationships between change in adiposity and change in cardiometabolic variables. Future research designed to primarily assess the effect of increased dairy product consumption on cardiometabolic disease risk factors in this population is warranted. Clinical Trial Registration: Clinicaltrials.gov; NCT#02581813.

Relationship Between Trajectories of Trunk Fat Development in Emerging Adulthood and Cardiometabolic Risk at 36 Years of Age.

OBJECTIVE: This study examined trajectories of trunk fat mass (FM) accrual during emerging adulthood of individuals categorized, at 36 years of age, as having higher compared with lower scores of (1) metabolic risk and (2) blood pressure risk. METHODS: Fifty-five individuals from the Saskatchewan Pediatric Bone Mineral Accrual Study (1991-2017) were assessed from adolescence (mean [SD], 11.5 [1.8] years) through emerging adulthood (26.2 [2.2] years) and into early adulthood (35.6 [2.2] years) (median 11 visits per individual). Sex-specific median splits of continuous standardized risk scores at 36 years of age were created. Dual-energy x-ray absorptiometry-assessed trunk FM trajectories were analyzed using multilevel random effects models. RESULTS: Higher risk scores of blood pressure risk and metabolic risk had significantly steeper trajectories of fat development (0.45 [0.11] and 0.44 [0.11] log g, respectively) than the lower risk scores. Dietary fat was not related (P > 0.05). Physical activity was negatively related (-0.04 [0.02] physical activity score) to trunk FM development during emerging adulthood. CONCLUSIONS: Young adults with higher metabolic risk at 36 years of age had greater trunk FM development during both adolescence and emerging adulthood, supporting the need for intervention at both these critical periods of fat accrual.