Interpretation of peak oxygen consumption in 10–12-year-old soccer players: effect of biological maturation and body size

The aim of this study was to investigate the effect of biological maturation and body size on aerobic capacity using appropriate scaling procedures in 10–12-year-old soccer players divided into late, average and early maturing boys. Peak oxygen consumption (VO2peak) was expressed as absolute values, ratio standards, theoretical exponents and experimentally observed exponents. VO2peak was not directly proportional to body mass as the experimentally observed exponent for body mass calculated through linear regression analysis yielded to b=0.64 (R2=0.62; p2peak expressed in l/min was different (p2peak values were adjusted for body mass (ml/min/kg), or when the effect of body mass was adjusted for using theoretical exponent scales (ml/kg0.67/min, ml/kg0.75/min) and experimentally observed exponent (ml/kg0.64/min), the VO2peak responses displayed relativeley constant values (p>0.05) throughout different maturation groups. Linear regression analyses indicated that after adjusting for the effects of body mass using the theoretical exponent scales (ml/min/kg0.67), biological maturation and body size had no effect on VO2peak values in young soccer players. In conclusion, the theoretical exponent scale for body mass (ml/kg0.67/min) control adequately for biological maturation and body size differences in VO2peak in 10–12-year-old soccer players. Therefore, more mature soccer players with better body size values should not be preferentially selected for young soccer teams

Caliper vs. Lipometer - comparing two methods of subcutaneous body fat measurement by Bland-Altman diagrams

Skinfold Calipers are widely used to obtain subcutaneous adipose tissue thickness because of its non-invasive, simple and inexpensive technique. Nevertheless, Caliper skinfold thicknesses have the disadvantage of measuring compressed adipose tissue and double layers of skin, which might reduce the precision of these results. In contrast, the computerized optical device Lipometer was developed to permit a quick, precise and non-invasive determination of non-compressed mono layers of subcutaneous adipose tissue thickness. In the present paper we investigate the hypothesis that Caliper skinfold thicknesses are significantly different from subcutaneous adipose tissue thicknesses in mm, which can be measured by Lipometer. Caliper and Lipometer results were obtained from 371 Estonian boys aged between 9.0 and 12.8 years. Measurements were performed at six different body sites: triceps, biceps, upper back, upper abdomen, hip and front thigh. Caliper measurements were systematically higher than Lipometer results in a range between 1.2 mm (hip) and 11.08 mm (front thigh). Comparing Caliper and Lipometer results very low measurement agreement was found. The two methods provided very poor interchangeability

Erinevate antropomeetriliste, füsioloogiliste ja biomehaaniliste näitajate mõju noorujujate ujumistulemusele

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Ujumises alustatakse tavaliselt raskete treeningutega enne puberteediea saabumist ja kõrge rahvusvaheline tase saavutatakse suhteliselt noores eas. Võistlusujumises on peamine eesmärki läbida võistlusdistants võimalikult kiiresti, kulutades selleks võimalikult vähe energiat. Seega on oluline hinnata ujujate ökonoomsust, mis on seotud erinevate antropomeetriliste, füsioloogiliste ja biomehaanilste näitajatega. Nende näitajate mõju täiskasvanud ujujate ujumistulemusele on uuritud suhteliselt palju. Kuid pikaajalisi uuringud kehaliste parameetrite, füsioloogiliste näitajate ja ujumise tehnika vahel on noortel ujujatel tehtud vähe. Võistlusspordis on oluline mõõta erinevaid sportlikke tulemusi mõjutavaid parameetreid võimalikult võistluslähedases situatsioonis. Seega on ujumise aegset hapnikutarbimist oluline mõõta just ujumise ajal (mitte näiteks veloergomeetril), arvestades seejuures erinavate tehnika- ja füsioloogiliste mõjutustega, mis annavad mõõdetavatele parameetritele suurema usaldusväärsuse. Antud, töö eesmärgiks oli uurida, millised parameetrid mõjutavad kõige enam noorujujate ujumistulemust kahe aastase uuringu perioodi jooksul. Tulemused näitasid, et kõige enam mõjutavad noorujujate ujumistulemust tehnika parameetrid, järgnesid antropomeetrilised ja füsioloogilised parameetrid. Seega oleks kõige olulisem noorte ujujate treenimisel pöörata esmast tähelepanu õige ujumistehnika õpetamisele ning kinnistamisele. Samuti tuleks pöörata tähelepanu noorujujate valikule, st. suuremat edu saavutavad need, kes on pikemad ja pikema kätesiruulatusega. Vähem mõjutavad ujumistulemust maksimaalne hapnikutarbimime või ujumise aegne energiakulu.Swimmers usually start serious training before the onset of puberty and achieve international competitive level at a relatively early age. Competitive swimming is a cyclic sport activity performed with the aim of covering the given distance as fast as possible to maximize metabolic power of the athlete and the economy of locomotion. Hence it is important to assess the individual economy of swimming and to understand the factors that determine swimming performance. Several investigations have studied different parameters and swimming performance of successful swimmers, but to our knowledge no studies have been conducted to study longitudinally the effect of different anthropometrical, physiological and biomechanical parameters on swimming performance in complex in young swimmers. In competitive sports it is important to assess different parameters in sport-specific conditions. Hence, it is important to measure maximal oxygen consumption during swimming (not, for example on cycle-ergometer), this enables the swimmer to perform swimming without restrictions and does not intervene with the swimming technique of the athlete. The aim of the present study was to investigate the impact of specific physiological, biomechanical and anthropometrical parameters on the development of swimming performance in young swimmers. The results of our study showed that biomechanical parameters characterized best the 400-m front-crawl swimming performance, followed by anthropometrical and physiological parameters. These results demonstrate that great emphasis should be on learning the correct swimming technique during the early years of training and the correct swimming technique learned during early years of swimming training is the basis for further development of sport-specific physiological measures during later years of swimming training. It is also important to pay attention to the selection process of young swimmers, but the influence of physiological parameters is not so noticeable

Associations of serum leptin, ghrelin and peptide YY levels with physical activity and cardiorespiratory fitness in adolescent boys with different BMI values

The aim of this study was to investigate the differences in associations of serum acylated and des-acylated ghrelin, peptide YY (PYY) and leptin levels with physical activity (PA) and cardiorespiratory fitness (CReF) in adolescent boys (mean age of 14.0 years) with overweight (OWB; n=55) and with normal weight (NWB; n=154). Methods: Total PA was measured by 7-day accelerometry (counts/min) and CReF by peak oxygen consumption (VO2peak/kg). Results: No differences were found in serum PYY, acylated ghrelin or des‑acyl ghrelin levels, whereas mean leptin (11.6±10.6 vs. 2.0±2.7 ng/ml; p<0.05) and insulin (18.1±8.7 vs. 11.0±6.2 mU/l; p<0.05) levels were significantly higher in OWB compared to NWB. Mean CReF was significantly lower in OWB compared to NWB (39.7±8.7 vs. 50.5±6.8 ml/min/kg; p<0.05). Leptin was negatively correlated with CReF in both groups (r=-0.43; p<0.05), des-acylated ghrelin with CReF only in OWB (r =-0.36; p<0.05). In OWB leptin was negatively correlated with total PA (r=-0.32; p<0.05) and positively with sedentary time of PA (r=0.35; p<0.05). In NWB 28.1% of the variability of CReF was determined by leptin and insulin resistance index (HOMA-IR), whereas in OWB 71.9% was determined by trunk FM and BMI. Conclusions: Leptin concentration was inversely associated with CReF in adolescent boys independently of BMI in both groups, while des-acylated ghrelin was associated with CReF only in OWB. Low PA in OWB was associated with high serum leptin level

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 (VO2peak) 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 (p0.694), 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; p0.311; p0.203; p<0.05) factors during all three measurement times

Physical activity and bone mineral accrual in boys with different body mass parameters during puberty: a longitudinal study.

The aim of our longitudinal study was to investigate the relationships between physical activity and bone mass in boys with different body mass status during the years surrounding pubertal growth spurt. Two hundred and six boys entering puberty took part in this study. The subjects were divided into underweight (BMI < 15.35), normal weight (BMI ≥ 15.35-21.22), overweight (BMI ≥ 21.22-26.02) and obese (BMI > 26.02) groups at baseline according to age related categories. Whole-body DXA scans were performed at baseline, after 12 and 24 months to assess body composition (lean body mass, fat mass), and total body (TB), lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD) parameters. Physical activity was measured by 7-day accelerometry. For longitudinal analysis, multilevel fixed effects regression models were constructed. Biological age, height and lean body mass had an effect for explanation of TB BMD, FN BMD and LS BMD. Moderate to vigorous physical activity (MVPA), vigorous physical activity (VPA) and sedentary time (SED) had the significant effect only on FN BMD. Being an underweight boy at the baseline indicated greater chance (p<0.01) to have lower TB BMD in the future (2 years at follow up) development, compared to normal weight (estimates = -0.038), overweight (estimates = -0.061) and obese boys (estimates = -0.106)