The purpose of this study was to examine the influence of the energy cost of swimming, body composition, and technical parameters on swimming performance in young swimmers. Twenty-nine swimmers, 15 prepubertal (11.9 +/- 0.3 years; Tanner Stages 1-2) and 14 pubertal (14.3 +/- 1.4 years; Tanner Stages 3-4) boys participated in the study. The energy cost of swimming (Cs) and stroking parameters were assessed over maximal 400-m front-crawl swimming in a 25-m swimming pool. The backward extrapolation technique was used to evaluate peak oxygen consumption (VO2peak). A stroke index (SI; m2 . s(-1) . cycles(-1)) was calculated by multiplying the swimming speed by the stroke length. VO2peak results were compared with VO2peak test in the laboratory (bicycle, 2.86 +/- 0.74 L/min, vs. in water, 2.53 +/- 0.50 L/min; R2 = .713; p = .0001). Stepwise-regression analyses revealed that SI (R2 = .898), in-water VO2peak (R2 = .358), and arm span (R2 = .454) were the best predictors of swimming performance. The backward-extrapolation method could be used to assess VO2peak in young swimmers. SI, arm span, and VO2peak appear to be the major determinants of front-crawl swimming performance in young 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 times 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 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 in sport-specific VO2 peak value from physiological characteristics, and improvement in stroke indices on biomechanical parameters. In addition, biomechanical factors characterised best the 400-m swimming performance followed by physical and physiological factors during the 2-yr. study period for the young male swimmers.

Rowing is a strength-endurance type of sport and competition performance depends on factors such as aerobic and anaerobic power, physical power, rowing technique and tactics. Therefore, a rower has to develop several capacities in order to be successful and a valid testing battery of a rower has to include parameters that are highly related to rowing performance. Endurance training is the mainstay in rowing. For the 2000 m race, power training at high velocities should be preferred to resistance training at low velocities in order to train more specifically during the off-season. The specific training of the international rower has to be approximately 70% of the whole training time. Several studies have reported different biochemical parameters for monitoring the training of rowers. There is some evidence that plasma leptin is more sensitive to training volume changes than specific stress hormones (e.g. cortisol, testosterone, growth hormone). In rowing, the stress hormone reactions to training volume and/or intensity changes are controversial. The Recovery-Stress Questionnaire for Athletes measures both stress and recovery, and may therefore be more effective than the previously used Borg ratio scale or the Profile of Mood States, which both focus mainly on the stress component. In the future, probably the most effective way to evaluate the training of rowers is to monitor both stress and recovery components at the same time, using both psychometric data together with the biochemical and performance parameters.

The purpose of present study was to investigate plasma adiponectin response to acute exercise in highly trained male rowers. Ten rowers performed a maximal 6,000-m rowing ergometer test [mean performance time approximately 20 min; 1,200.8 (29.9) s], and venous blood samples were obtained before, immediately after and after 30 min of recovery. In addition to adiponectin concentration, leptin, insulin, growth hormone and glucose values were measured. Adiponectin was not changed immediately after the exercise when uncorrected for plasma volume changes (-8.1%; P>0.05). However, adiponectin was decreased immediately after the exercise when adjusted for plasma volume changes (-11.3%; P<0.05). Adiponectin was significantly increased above the resting value after the first 30 min of recovery (uncorrected for plasma volume, +19.3%; corrected for plasma volume, +20.0%). No changes occurred in plasma leptin and insulin concentrations with exercise (uncorrected for plasma volume changes). While growth hormone and glucose values were significantly increased and decreased to the pre-exercise level immediately after the exercise and after the first 30 min of recovery, respectively (uncorrected for plasma volume changes), no differences in the responses to exercise were observed in these measured blood parameters when adjusting for plasma volume changes. There were no relationships between plasma adiponectin and other measured blood parameters before and after the exercise, nor were changes in adiponectin related to changes in other measured blood biochemical values after the exercise. These results suggest that plasma adiponectin is altered as a result of maximal acute exercise in highly trained athletes.

Jü rimäe J, Jü rimäe T. Plasma adiponectin concentration in healthy pre-and postmenopausal women: relationship with body composition, bone mineral, and metabolic variables. Am J Physiol Endocrinol Metab 293: E42-E47, 2007. First published March 6, 2007; doi:10.1152/ajpendo.00610.2006.-The aim of the current investigation was to determine the possible relationships of fasting adiponectin level with body composition, bone mineral, insulin sensitivity, leptin, and cardiorespiratory fitness parameters in 153 women. Subjects were classified as premenopausal (n ϭ 42; 40.8 Ϯ 5.7 yr) if they had regular menstrual periods, early postmenopausal (n ϭ 49; 56.7 Ϯ 3.6 yr) if they had been postmenopausal for more than Ͼ1 yr but Ͻ7 yr (5.5 Ϯ 1.3 yr), and postmenopausal (n ϭ 62; 72.2 Ϯ 4.5 yr) if they had been postmenopausal for Ͼ7 yr. All women studied had a body mass index (BMI) Ͻ30 kg/m 2 . Adiponectin values were higher (P Ͻ 0.05) in middle-aged (12.0 Ϯ 5.1 g/ml) and older (15.3 Ϯ 7.3 g/ml) postmenopausal women compared with middle-aged premenopausal women (8.4 Ϯ 3.2 g/ml). Mean plasma adiponectin concentration in the total group of women (n ϭ 153) was 12.2 Ϯ 6.3 g/ml and was positively related (P Ͻ 0.05) to age, indexes of overall obesity (BMI, body fat mass), and cardiorespiratory fitness (PWC) values. In addition, a negative association (P Ͻ 0.05) between adiponectin with central obesity (waist-to-hip and waist-to-thigh ratio), fat-free mass, bone mineral (bone mineral content, total and lumbar spine bone mineral density), and leptin and insulin resistance (insulin, fasting insulin resistance index) values was observed. However, multivariate regression analysis revealed that only age, fasting insulin resistance index, and leptin were independent predictors of adiponectin concentration. In conclusion, circulating adiponectin concentrations increase with age in normal-weight middle-aged and older women. It appears that adiponectin is independently related to age, leptin, and insulin resistance values in women across the age span and menstrual status. adiponectin; leptin; age; menopausal status; insulin resistance HUMAN ADIPOSE TISSUE has long been perceived predominantly as a storage depot for energy surplus. However, recent research in the biology of adipose tissue indicates that it is not simply an energy storage organ but also a secretory organ that synthesizes and secrets multiple cytokine proteins that modulate various biological functions (8,15,17). The number and range of identified adipocytokines is continuing to expand rapidly (28), but the exact role of them in the regulation of human metabolism is still unknown. These proteins include adipsin, resistin, tumor necrosis factor-␣ (TNF-␣), leptin, and adiponectin (8, 28). Adiponectin was first identified by Scherer et al. (26) and is one of the most abundant circulating adipose tissue-specific adipocytokines. Adiponectin is structurally similar to TNF-␣ and is produced in visceral, subcutaneous, and bone marrow fat depots (30).Several studies have demonstrated that...