Physical development and swimming performance during biological maturation in young female swimmers

The present study analyzed the development of physiological, biomechanical and anthropometrical parameters in young female swimmers and assessed the effect of these parameters on swimming performance during biological maturation. In total, 26 female swimmers participated in the study in which data were annually collected for two consecutive years. Body composition, basic anthropometrical parameters and biological age were measured. During the 400 m front-crawl swimming, the energy cost of swimming and stroking parameters were assessed. Peak oxygen consumption (VO2 peak) was assessed by means of the backward-extrapolation technique recording VO2 during the first 20 sec of the recovery period after a maximal trial of 400 m distance. During the 2 year follow-up study period, age, height, body mass, body fat %, fat free mass, bone mineral mass, total bone mineral density, arm span and biological maturation values significantly increased during each year (p<0.05). The tracking of the physical characteristics measured over the 2-years study period was relatevely high (r > 0,694), except for the body fat% (r>0.554). The tracking of the Tanner stages was also high (r = 0.759-0.780). Stepwise regression analyses showed that biomechanical factors (R2 > 0.322;p<0.05) best characterized the 400 m swimming performance in young female swimmers, followed by bioenergetical (R2 > 0.311; p< 0.05) and physical (R2>0.203;p<0.05) factors during all three measurement times

Longitudinal development of physical and performance parameters during biological maturation of young male swimmers

The aim of the study was to examine the development of specific physical, physiological, and biomechanical parameters in 29 young male swimmers for whom measurements were made three time for two consecutive years. During the 400-m front crawl swimming, the energy cost of swimming, and stroking parameters were assessed. Peak oxygen consumption (VO2 peak) was assessed by means of the backward-extrapolation technique recording VO2 during the first 20 sec. of recovery period after a maximal trial of a 400 m distance. Swimming performance at different points of physical maturity was mainly related to the increases in body height and arm-span values from physical parameters, improvement of VO2 peak value from physiological characteristics, and improvement in stroke indices on biomechanical parameters. In addition, biomechanical factors characterized best the 400 m swimming performance followed by physical and physiological factors during the 2-yr. study period for the young male swimmers

Biomechanics and bioenergetics of front crawl swimming in young female swimmers

The purpose of this study was to examine the influence of energy cost of swimming, anthropometrical/body composition and technical parameters on swimming performance in youn swimmers. Twenty six girls, 14 prepubertal (11.1 +- 0.7 yrs; Tanner stages 1-2) and 12 pubertal (14.7+-1.6 yrs; Tanner stages 3-4) girls participated in the study. Energy cost of swimming (Cs) and stroking parameters were assessed over maximal 400 metre front crawl swimming in a 25 metre swimming pool. The backward extrapolation technique was used to evaluate peak oxygen consumption (VO2 peak) in addition to assessed VO2 peak on a cycle ergometer. A stroke index (SI,m2.s-1 cycle-1) was calculated by mulpiplying the swimming speed by the stroke length. Correlation analysis indicated that SI ( r = - 0.92), VO2 peak ( r = - 0.48) and fat free mass ( r = - 0.61) were the best predictors ( p > 0.001) of swimming performance in studied young swimmers. In addition the backward extrapolation technique could be used to asses Vo2peak in youn swimmers in sport specific conditions. In conclusion, the SI, fat frre mass and VO2peak appear to be the major determinants of ront crawl swimming performance in young female swimmers

Influence of pubertal development on ghrelin in young swimmers:a longitudinal study

Ghrelin is a newly peptide hormone, discovered in 1999 who is involved in many biological processes in man. Is linked to appetite regulation, influenced by sleep, and to many physiological parameter linked with growth.No longitudinal studies exists in children and boys studying the time-course of ghrelin secretion along years of pubertal development. Ghrelin is influenced by physical activity, and children who practise intensively sports can show alterations in ghrelin concentrations

The impact of ghrelin on bone mineral density in boys : effect of biological maturation and physical activity

The aims of the present study were to: 1) assess the influence of regular phsyical activity on ghrelin concentration in prepubertal and pubertal boys; and 2) examine the impact of ghrelin and insulin like growth factor-I (IGF-I) concentrations on bene mineral density (BMD) in boys with different physical activity patterns at different pubertal stages. In total, 56 healthy schoolboys aged between 10 and 16 years were divided into the swimming (n=28) and the control (n=28) groups. The subjects were matched by age and body mass index (BMI) genrating 9 matches pairs in pubertal group I (Tanner stage 1), 11 pairs in group II (pubertal stages 2 & 3) and 8 pairs in group III (pubertal stages 4 & 5). To reduce the effect of body size on BMD vaues, apparent volumetric bone mineral density (BMAD) of the lumbar spine was calculated. Swimers in pubertal groups IIand III had significantly (both p < 0.05) higher mean plaslma ghrelin concentration than the control groups. In conclusion plasma ghrelin concentrations decreased durign puberty in physically inactive boys, while in regularly physically active boys it remained relatevely unchanged

Regular Physical Activity Influences Plasma Ghrelin Concentration in Adolescent Girls

Purpose: We examined the effect of regular physical activity on plasma ghrelin concentration after onset of puberty in girls. In addition, we also examined the association of fasting plasma ghrelin concentration with various plasma biochemical , body composition, and anaerobic capacity variables in healthy adolescent girls. Method: fifty healthy schoolgirls ages 11 to 16 yr were divided either into a phsyically active (N = 25) or a physically inactive (N = 25) group. The physically active group consisted of swimmers who had trained on an average of 6.2 +/- 2. h.wk-1 for the last 2 yrs, whereas the inclusion criterion for the physically inactive group was the participation in physical education classes only. The subjects were matched for age (+/- 1 years) and body mass index (BMI +/- 2 kg.m-2). Maturation I group (14 matched pairs) included pubertal stages 2 and 3, and maturation II group (11 matched pairs ) included pubertal stages 4 and 5. Results: physically active girls had significantly higher (p < 0.05) mean plasma ghrelin levels than the physically incative girls (maturation I: 1152.1 +/- 312.9 vs 877+/- 114.8 pg.mL-1; maturation II: 1084 +/- 252.5 vs 793.4 +/- 164.9 pg.mL-1). Plasma ghrelin concentration was negatively related to percent body fat, fat mass, peak oxygen consumption per kilogram of body mass, leptin, estradiol, insulin, and insulin-like growth factor-I(IGF-I)(r > 0.298; P < 0.05). Multivariate linear regression analysis to determine ghrelin concentration using the variables that were significantly associated with ghrelin concentration demonstrated that plasma IGF-I was the most important predictor of plasma ghrelin concentration (b =-0.396; P = 0.008). Conclusion: regular physical activity influences plasma ghrelin concentration in girls with different pubertal maturation levels. Plasma IGF-I concentration seems to be the main determinant of circulating ghrelin in healthy, normal weight adolescent girls

Effect of pubertal development and physical activity on plasma ghrelin concentration in boys

The aim of the present study is to assess the influence of physical activity on a new hormone , ghrelin, who is involved in many physiological as well psychological processes