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Results: The equation for total energy expenditure (cal x min-1 x kg-1) was found to be 34. 44 + 0.22 x counts x 15s-1 and for activity energy expenditure 5,35 + 0,22 x counts x 15s-1. Accelerometer output explained 83% (95% CI; 0.77 to 0.89) and 86% (95% CI: 0,81 to 0,91), of the variance in total energy expenditure and activity energy expenditure, respectively. The explained variances were generally higher for prediction of activity intensity (METs) than energy expenditure (EE or AEE). Cut-off limits (95% CI) for inactivity (1.5 METs), moderate intensity (3 METs) and vigorous intensity (6 METs) respectively was found to be 83 counts x 15s-1 (75 to 91), 251 counts x 15s-1 (226 to 274) and 584 counts x 15s-1 (531 to 637), respectively. Gender, age, resting energy expenditure and anthropometric variables increased precision only marginally.
Discussion: The present study indicates that a motion sensor, worn on the wrist of the non-dominant arm, appears to be valid for estimating energy expenditure and physical activity intensity in children aged 8 to 10 yrs. The proposed cut-off limits may be used to record time spent in physical activity of different intensities. Other measures of physical activity, such as self-reported data or direct observation, are generally less valid in children (Welk GJ et al), possibly due to the intermittent nature of their movement. Additionally, the placement on the wrist is comfortable and makes it possible to wear the monitor continuously for several days, without taking it off.
References Steele RM, Brage S, Corder K, Wareham NJ, Ekelund U (2008) J Appl Physiol. 105(1):342-51.
Welk GJ, Corbin CB, Dale D. (2000) Res Q Exerc Sport. 71(2 Suppl):S59-73.
HABITUAL RESISTANCE TRAINING IN MEN ASSOCIATES WITH GREATER FOREARM VENOUS COMPLIANCEKAWANO, H.
WASEDA UNIVERSITYBACKGROUND and PURPOSE: Venous compliance of the extremities is a major determinant of the amount of blood that may be translocated to the central region, because small changes in peripheral blood volume can greatly impact cardiac filling pressure and subsequently cardiac output. It is reported that the venous compliance is reduced with age in sedentary and endurance-trained men, but compliance is greater preserved in endurance trained-men. Aerobic exercise as well as resistance exercise has become a popular modality of exercise performed by most populations, and has become an integral component of exercise recommendations endorsed by a number of national health organizations. It remains unclear, however, whether habitual resistance training affects venous compliance. The purpose of the present study was to compare the venous compliance in daily resistance-trained men with age-matched control men.
METHODS: Eleven resistance-trained middle-aged men (age, 37.7±1.5 yrs; height, 171.3±1.9 cm; body weight, 75.6±2.2 kg) and thirteen age-matched controls (age, 36.7 ± 1.6 yrs; height, 171.6±1.6 cm; body weight, 73.4±1.9 kg) were studied. Resistance-trained men had
14 ANNUAL CONGRESS OF THE EUROPEAN COLLEGE OF SPORT SCIENCETH Wednesday, June 24th, 2009 been performing resistance training for over10 years. Changes in forearm volume were measured noninvasively using strain-gauge plethysmography at the maximal forearm circumference. Forearm venous compliance was measured in supine subjects by inflating a venous collecting cuff, placed around the upper arm, to 60 mmHg for 8 min and the decreasing cuff pressure at 1 mmHg/s to 0 mmHg.
Forearm venous compliance was determined using the first derivative of the pressure-volume relation during cuff pressure reduction (compliance = β1 + 2•β2•cuff pressure).
RESULTS: The leg extension power and the handgrip strength in resistance-trained men were significantly higher than those in control men (2293±155 vs 1693±99 watts, 52.6±1.3 vs 44.3±1.9 kg, respectively; both p0.05). Systolic blood pressure and mean arterial pressure were significantly higher in resistance-trained men as compared with control peers (132±4 vs 116±3 mmHg, 95±3 vs 85±2 mmHg, respectively; both p0.05). There were no group differences in maximal oxygen consumption, resting or maximal heart rate, blood glucose, HDL-cholesterol and triglyceride. Forearm venous compliance at 20 mmHg cuff pressure was 16% greater in resistance-trained men as compared with age-matched sedentary controls (0.097±0.005 ml/dl/mmHg vs 0.083±0.004ml/dl/mmHg, p0.05).
CONCLUSIONS: These results of the present study indicate that performing chronic resistance training may increase venous compliance in middle-aged men, suggesting that greater venous compliance with habitual resistance exercise may have important implications regarding arterial blood pressure regulation during orthostatic stress or during exercise in healthy adult men.
BONE MINERAL DENSITY AND IGF-1 IN 13-15 YEAR OLD FEMALE ATHLETESGRUODYTE, R., JÜRIMÄE, J., SAAR, M., JÜRIMÄE, T.
UNIVERSITY OF TARTU; LITHUANIAN ACADEMY OF PHYSICAL EDUCATION, LITHUANIAIntroduction: It is well known that insulin-like growth factor-1 (IGF-1) is an effective osteoporotic growth factor, which increase dramatically during puberty, augmented by the increasing levels of sex steroids, and positively affects bone turnover by stimulating osteoblasts proliferation and differentiation (Davies et al., 2005). Bone mineralization increases with age, height, and body mass increase throughout childhood, with a significant gain during pubertal development, resulting in an increase of BMD of about 40% during this period (Gordon, 1991). The aim of this cross-sectional study was to evaluate the relationships between BMD and IGF-1 in adolescent female athletes.
Methods The participants were eighty 13-15 year-old girls comprising three groups: gymnasts (n=23), sprinters (n=24) and controls (n=33). Body height and body mass were measured, and body mass index (BMI) was calculated (kg/m2). BMD at lumbar spine (L2-L4) and femoral neck (FN) were measured by DXA. Morning fasting blood samples were collected for analysis of IGF-1 and IGFBP-3, and IGF-1/IGFBP-3 molar ratio was calculated. For those girls who had menarche, the fasting blood samples were drawn on early follicular phase of the menstrual cycle.
Results: Gymnasts BMD FN was significantly higher than sprinters and controls (1.13 ± 0.15 vs. 1.05 ± 0.09 and 1.01 ± 0.11 g/cm2, respectively). The levels of IGFBP-3 were significantly greater in gymnasts than in sprinters (6.0 ± 0.7 vs. 5.5 ± 0.7 mg/L, respectively). There were significant correlations of IGF-1 and IGF-1/IGFBP-3 molar ratio with BMD FN and L2-L4 (r = 0.39-0.59) in gymnast and control groups, but not in sprinters. After adjusting for age, body height and body mass, the significant correlations between IGF-1 and BMD variables (r = 0.49-0.52) were revealed in gymnast group only. Stepwise multiple regression analysis indicated that BMD FN and L2-L4 were influenced by IGF-1 up to 31.0-34.6 % (R2x100) in gymnasts, and by IGF-1/IGFBP-3 – up to 19-32 % (R2x100) in controls.
Discussion: In our study, no significant differences between the groups were found in respect to IGF-1 levels and IGF-1/IGFBP-3 ratio, but BMD FN was significantly greater in gymnasts. Previously, IGF-1/IGFBP-3 was indicated as the most robust predictor of femoral neck BMD in young adult women with different physical activity patterns (Snow et al., 2000). This corresponds well with our research findings, although the significant relationships of BMD FN and L2-L4 with IGF-1 levels and IGF-1/IGFBP-3 ratio were found in pubertal gymnast and controls, but not in sprinters. We conclude that IGF-1 is strongly correlated with BMD FN and L2-L4 in adolescent gymnasts, but not sprinters.
References Gordon CL, Halton JM, Atkinson SA (1991) Growth Dev. Aging, 55: 257-262.
Davies JH, Evans BAJ, Gregory JW (2005) Arch Dis Child, 90:373-8.
Snow CM, Rosen CJ, Robinson TL (2000) Med Sci Sports Exerc, 32(11):1902-7.
THE CELLULARITY OF ADIPOCYTE AND SECRETION OF ADIPOCYTOKINES DURING AND AFTER VOLUNTARY WHEEL
RUNNING EXERCISE IN HYPERPHAGIC AND OBESE OLETF RATSKIMURA, M., SHINOZAKI, T., TAKIUE, Y., HOSOYAMADA, M., SHIBASAKI, T.
The purpose of this study was to investigate the optimal weight reduction program for the exercise therapy. We tested about the relationships between cellularity of adipocytes and secretion of adipocytokines at the end and 2-day after of voluntary wheel running exercise.
Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of hyperphagia and obesity, were used in this study (19-week-old at the end of experiment). The rats were randomly assigned to either the 4-week voluntary wheel running exercise (15 to 19-week-old) or control group (Cont). The half numbers of exercising rats were killed at the end of exercise period (Ex-end), and the others were assigned to the 2-day recovery period at which these rats were prohibited from accessing to running wheel (Ex-recov). Throughout the experimental period, all rats were provided with water and standard chow food ad libitum. For the quantification of number and size of adipocyte, adipose tissue were fixed with 10% formalin phosphate buffer, and the sectional cell diameter of adipocyte were analyzed in the hematoxylin and eosin stained preparations. Adipocytokine levels in blood were measured using ELISA kit.
Compared to Cont group, Ex-end group exhibited the remarkable reduction in body weight, abdominal fat pad weight, blood leptin concentration, and size of adipocyte in abdominal fat pads. Compared to Ex-end group, Ex-recov group provided a marked increase in body weight, although there were no changes in weight and size of adipocyte in abdominal fat pads. Unexpectedly, blood leptin concentrations in Ex-recov group were higher than in Ex-end group.
These results suggested that the regulatory mechanism in expression and/or secretion of leptin from adipocyte is different between during and after exercise therapy.
IS SKELETAL MUSCLE LEPTIN SENSITIVITY REDUCED BY BED REST?FUENTES, T., GUERRA, B., GUADALUPE-GRAU, A., SANTANA, A., MORALES-ALAMO, D., PILEGAARD, H., CALBET, J.A.L.
ULPGC (LAS PALMAS GC, SPAIN). GENETIC UNIT CHIMI (LAS PALMAS GC, SPAIN). RESEARCH UNIT HGCDRN (LAS PALMAS GC, SPAIN). DEPARTMENT OF BIOLOGY CU (COPENHAGEN, DENMARK).Human obesity is mainly caused by a sedentary life style and is characterised by a high concentration of leptin in plasma associated with leptin and insulin resistance in peripheral tissues, such as skeletal muscle. Skeletal muscle expresses long and short protein isoforms of the leptin receptor. A mechanism that could explain skeletal muscle leptin resistance in obesity is a down-regulation of leptin receptors (OB-Rs) and/or up-regulation of suppressor of cytokine signaling 3 (SOCS3) and protein-tyrosine phosphatase 1B (PTP1B) which are negative regulators of insulin and leptin signaling. Both obesity and bed rest may induce inflammation and according to rodent experiments PTP1B protein expression may be increased by inflammation in skeletal muscle. Therefore, the aim of this study was to test the hypothesis that bed rest causes down- and upregulation of OB-R and SOCS3/PTP1B protein expression, respectively, in human skeletal muscle.
Methods. Deltoid and Vastus Lateralis muscle biopsies were obtained from 12 healthy men before and after one week bed rest performed in eucaloric conditions (mean ± SD, age: 26.2 ± 5.3 years; height: 181.7 ± 6.1 cm; body mass: 75.5 ± 11.2 kg; BMI: 22.8 ± 2.7 kg/m2 and VO2max: 3.9 ± 0.8 L/min). Total protein extracts were prepared from muscle biopsies and OB-R, SOCS3 and PTP1B protein expression was analyzed by Western blot. Serum leptin and soluble isoform of the leptin receptor (sOB-R) concentrations were determined by ELISA before and after bed rest.
Results. Serum leptin concentration was increased by 26% after bed rest compared with before bed rest (P0.05). However, serum s-OBR concentration was unaffected by bed rest (P=0.6). Alpha tubulin protein expression, used as a loading control in our immunoblotting assays, was not affected by bed rest in either the deltoid or Vastus Lateralis muscle biopsies (both P0.05 compared with before bed rest). OB-R (short and long isoforms) and SOCS3 protein expression normalized to alpha-tubulin was unchanged after bed rest compared with before bed rest in deltoid and Vastus Lateralis muscles (all P0.05). PTP1B protein expression normalized by alpha-tubulin was unaffected by bed rest in deltoid muscle biopsies (P0.05). However, PTP1B protein content in Vastus Lateralis muscle was 90% higher after bed rest than before bed rest (P0.01).
Conclusions. PTP1B protein expression is markedly increased in human Vastus Lateralis but not in the deltoid muscles after one week of bed rest. Since PTP1B is able to dephosphorylate the insulin receptor and also the Janus Kinase 2 (JAK2) (first step in leptin signalling), it may induce both insulin and leptin resistance. Moreover, our results indicate that one-week bed rest elicits leptin resistance as reflected by the increased basal leptin serum concentration and its free fraction, despite no significant changes in body fat mass.
References. Guerra et al. PLoS ONE 3, e3466 (2008). Guerra et al. J Appl Physiol 102, 1786 (2007).
Granted by the Ministerio de Ciencia e Innovación (BFU2006-13784 and FEDER) and the Lundbeck Foundation.