Comparison of IPAQ-SF and Two Other Physical Activity Questionnaires with Accelerometer in Adolescent Boys.

Self-report measures of physical activity (PA) are easy to use and popular but their reliability is often questioned. Therefore, the general aim of the present study was to investigate the association of PA questionnaires with accelerometer derived PA, in a sample of adolescent boys. In total, 191 pubertal boys (mean age 14.0 years) completed three self-report questionnaires and wore an accelerometer (ActiGraph GT1M) for 7 consecutive days. The PA questionnaires were: International Physical Activity Questionnaire-Short Form (IPAQ-SF), Tartu Physical Activity Questionnaire (TPAQ), and the Inactivity subscale from Domain-Specific Impulsivity (DSI) scale. All three questionnaires were significantly correlated with accelerometer derived MVPA: the correlations were 0.31 for the IPAQ-SF MVPA, 0.34 for the TPAQ MVPA and -0.29 for the DSI Inactivity scale. Nevertheless, none of the questionnaires can be used as a reliable individual-level estimate of MVPA in male adolescents. The boys underreported their MVPA in IPAQ-SF as compared to accelerometer-derived MVPA (respective averages 43 and 56 minutes); underreporting was more marked in active boys with average daily MVPA at least 60 minutes, and was not significant in less active boys. Conversely, MVPA index from TPAQ overestimated the MVPA in less active boys but underestimated it in more active boys. The sedentary time reported in IPAQ-SF was an underestimate as compared to accelerometer-derived sedentary time (averages 519 and 545 minutes, respectively).

Body composition, maximal aerobic performance and inflammatory biomarkers in endurance-trained athletes.

This study was designed to examine the relationships between body composition, cardiorespiratory fitness and simultaneously measured inflammatory parameters in endurance-trained athletes. In 20 well-trained rowers (19·0 ± 2·9 years; 185·6 ± 4·8 cm; 85·7 ± 10·8 kg; 17·1 ± 5·1% body fat; maximal oxygen consumption [VO2 max]: 63·9 ± 8·5 ml min-1  kg-1 ), body composition was measured by dual-energy X-ray absorptiometry and cardiorespiratory fitness by direct VO2 max test. Twelve inflammatory factors [interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-gamma (IFN-γ), tumour necrosis factor-alpha, IL-1α, IL-1ß, monocyte chemoattractant protein-1 (MCP-1), epidermal growth factor (EGF)] were analysed from serum samples. Serum IFN-γ was related (P<0·05) to fat-free mass (FFM) (r = -0·56) and muscle mass (r = -0·50). The stepwise regression analysis showed that IFN-γ explained 27·5%, and IFN-γ and IL-6 together explained 39·8% of the variability of FFM, while IFN-γ explained 21·1%, and IFN-γ together with EGF explained 36·6% of the variability of muscle mass in male rowers. Serum IL-8 (r = -0·65) and VEGF (r = -0·48) correlated (P<0·05) with VO2 max kg-1 . Serum IL-8 explained 38·5% of the variability of VO2 max kg-1 . Significant correlations were also found among several inflammatory parameters, indicating that various inflammatory cytokines act on the body as an ensemble. In conclusion, this cross-sectional study in endurance-trained male rowers showed that FFM and muscle mass were negatively correlated with serum IFN-γ level, whereas cardiorespiratory fitness was negatively related to serum IL-8 level.

Longitudinal associations between bone and adipose tissue biochemical markers with bone mineralization in boys during puberty.

BACKGROUND: We investigated longitudinal relationships between the biochemical markers of bone and adipose tissue with bone mineral content (BMC), bone mineral density (BMD), moderate-to-vigorous physical activity (MVPA) and sedentary time (SED) in pubertal boys. METHODS: Ninety-six boys (11.9 ± 0.6 years old) were measured at baseline, after 12 and 24 months. Body composition (fat mass [FM], lean body mass [LBM]), and whole body (WB), lumbar spine (LS) and femoral neck (FN) BMD and BMC were assessed. Additionally, serum leptin, adiponectin, osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX) were measured. RESULTS: OC had a strong longitudinal inverse effect on changes in WB_BMD (p < 0.001) and LS_BMD (p = 0.021), while CTX had an inverse effect only on changes in FN_BMD (p = 0.011). Leptin had an inverse effect on changes in WB_BMC/WB_BMD (p = 0.001), FN_BMD (p = 0.002) and LS_BMD (p = 0.001). MVPA showed a longitudinal inverse effect on changes in leptin (p = 0.030), however no longitudinal effect of SED to biochemical markers of bone and adipose tissue was found. CONCLUSIONS: Bone metabolism markers have negative effect on bone mineral accrual during puberty. Increases in MVPA affect leptin, suggesting a positive link of MVPA through leptin metabolism on increases in bone mineralization during puberty.

Cardiovascular fitness, physical activity, and metabolic syndrome risk factors among adolescent estonian boys: A longitudinal study.

OBJECTIVES: The aim was to examine the changes in metabolic syndrome risk factors over a 2-year period, and to investigate the independent influence of baseline physical activity (PA) and cardiovascular fitness (CVF) on these changes. METHODS: 120 Estonian boys (age at baseline 11.9 ± 0.1 years) were grouped according to baseline PA or CVF/kg (VO2max/kg ) and CVF/LBM (VO2max/LBM ). PA was assessed by 7-day accelerometry. Total cholesterol (TC), high-density lipoprotein (HDL), triglycerides (TRG), insulin and glucose were measured and assessment for insulin resistance (HOMA-IR) and TC/HDL ratio were calculated. RESULTS: In both CVF/kg and CVF/LBM , the low CVF groups had significantly higher values of HOMA-IR (P < 0.009) over time. In TRG and TC/HDL ratio values the only significant difference over time emerged between CVF/kg groups (P < 0.001). Participants in high metabolic risk CVF/kg group were 5.9 times more likely to have high HOMA-IR values, 2.9 times more likely to have high triglyceride values, and 3.5 times more likely to have high TC/HDL ratio values (P ≤ 0.045) in the second year follow-up compared to those who were in the low metabolic risk CVF/kg group. In moderate-to-vigorous PA groups there were no significant differences between HOMA-IR, TRG, and TC/HDL ratio values over time. CONCLUSIONS: The results of the study indicate that CVF has a stronger longitudinal prediction value compared to moderate to vigorous physical activity in terms of metabolic risk factors in adolescent boys. Fitness remained a significant predictor if the influence of body fatness was removed from the analysis. Am. J. Hum. Biol. 28:782-788, 2016. © 2016Wiley Periodicals, Inc.

Adipocytokines and bone metabolism markers in relation to bone mineral values in early pubertal boys with different physical activity.

BACKGROUND: We aimed to examine the associations of adipocytokines and circulating bone metabolism markers with bone mineral parameters in early pubertal boys with different physical activity level. METHODS: Eighty-six early pubertal boys were divided into active and non-active boys according to the accumulated moderate-to-vigorous physical activity (MVPA) level. Body composition and bone mineral parameters were assessed and testosterone, leptin, adiponectin, osteocalcin (OC), and C-terminal telopeptide of type I collagen (CTX) were measured. RESULTS: Active subjects had significantly lower (p<0.05) body mass, body mass index (BMI), fat mass (FM), leptin, and sedentary time values, while non-active subjects had lower (p<0.05) vigorous physical activity level and femoral neck bone mineral density (FN-BMD). OC contributed to the models in physically active group and explained 6.6% and 9.7% of variance in whole body (WB) [F(5,44)=10.847; p<0.001] and lumbar spine bone mineral content (LS-BMC) [F(5,44)=4.158; p=0.004], respectively. No other biochemical parameters were found to be related to bone mineral parameters in either the active or non-active group. CONCLUSIONS: Bone metabolism markers were positively correlated with bone mineral values only in active pubertal boys. Leptin and adiponectin were not related to bone mineral parameters in active and non-active pubertal boys.

Adipocytokine and ghrelin levels in relation to bone mineral density in prepubertal rhythmic gymnasts entering puberty: a 3-year follow-up study.

PURPOSE: To investigate changes in bone mineral density (BMD) in rhythmic gymnasts (RG) entering puberty and their age-matched untrained controls (UC) over the 36-month period, and associations with leptin, adiponectin and ghrelin over this period. METHODS: Whole body (WB), lumbar spine (LS) and femoral neck (FN) BMD, WB bone mineral content (BMC), and leptin, adiponectin and ghrelin were measured in 35 RG and 33 UC girls at baseline and at 12-month intervals over the next 3 years. The change over the 36 months was calculated (∆ score). RESULTS: The pubertal development over the next 36 months was slower in RG compard to UC, while there was no difference in bone age development between the groups. BMD at all sites was higher in RG in comparison with UC at every measurement point. ∆LS BMD and ∆FN BMD, but not ∆WB BMD and ∆WB BMC, were higher in RG compared with UC. None of the measured hormones at baseline or their ∆ scores correlated with ∆BMD and ∆BMC in RG. Baseline fat free mass correlated with ∆WB BMD and ∆WB BMC in RG, while baseline leptin was related to ∆WB BMC, ∆WB BMD and ∆LS BMD in UC. CONCLUSIONS: Measured baseline hormones and their ∆ scores did not correlate with increases in bone mineral values in RG entering puberty. Although the pubertal development in RG was slower than in UC, high-intensity training appeared to increase BMD growth and counterbalance negative effects of slow pubertal develpment, lower fat mass and leptin in RG.

Acute inflammatory response to prolonged sculling in competitive male rowers.

BACKGROUND: This study examined the effects of a prolonged low-intensity single scull rowing exercise on a complex of 12 different inflammatory cytokines in rowers. METHODS: Twenty male rowers (19.0±2.9 yrs; 185.6±4.8 cm; 85.7±10.8 kg; 17.1±5.1% body fat; maximal oxygen consumption [VO2max]: 63.9±8.5 mL.min.-1kg-1) completed a rowing training session lasting about 2-h (distance: 21.4±1.8 km; heart rate [HR]: 139±8 beats.min-1; intensity: 79.9±3.6% of the anaerobic threshold) followed by a 30-min rest. Venous blood samples were collected before and after on-water rowing, and analyzed for blood white cell count (WBC), high sensitive C-reactive protein (hsCRP), and 12 inflammatory cytokines (interleukin [IL]-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-gamma, tumor necrosis factor-alpha, IL-1α, IL-1ß, monocyte chemotactic protein-1 [MCP-1], epidermal growth factor). RESULTS: Exercise induced significant (P<0.05) increment in WBC, hsCRP, IL-6, IL-10 and MCP-1 concentrations. The long-distance sculling intensity variables such as the average rating of perceived exertion, HR and blood lactate were correlated with changes in IL-8, IL-1α and IL-1ß levels (r=0.47 to r=0.59; P<0.05). Maximal aerobic performance variables (VO2max and maximal aerobic power) were related to changes in IL-2, IL-4, IL-8 and IL-1ß levels (r=-0.45 to r=-0.54; P<0.05). CONCLUSIONS: Acute exercise-induced inflammatory reaction was reflected by a significant increase in serum IL-6, IL-10 and MCP-1 levels. Variance in exercise-induced increases in inflammatory markers in response to 2-h of endurance exercise was explained by aerobic performance and exercise intensity levels in competitive male rowers.

Spinal posture in different DanceSport dance styles compared with track and field athletes.

BACKGROUND AND OBJECTIVE: In DanceSport, athletes train for many years to develop a very specific posture. Presently there are few data as to whether these adaptations are habitual or cause permanent anatomical changes to the spine. The aim of the current study was to evaluate lumbar lordosis and thoracic kyphosis of the international level DanceSport dancers using track and field athletes as controls. MATERIALS AND METHODS: Thirty competitive DanceSport couples (15 men aged 23.4±6.6 years; 15 women aged 22.5±6.4 years) and 29 track and field athletes (16 mean aged 27±4.4 years and 13 women aged 22±4.1 years) volunteered. Twelve couples were Standard, 7 Latin American and 11 were Ten Dance couples. Thoracic kyphosis and lumbar lordosis angle were assessed in lateral view using a Vertebral Fracture Assessment scan. RESULTS: DanceSport athletes had smaller S-shaped vertebral curvatures compared to track and field athletes. Male (5.7±4.7°) and female dancers (8.7±5.9°) had significantly smaller lumbar lordosis angle compared to their track and field counterparts (22.3±9.9° for men; 20.3±5.9° for women). Female dancers (25.3±8.0°) also demonstrated significantly smaller thoracic kyphosis angle than female track and field (32.1±8.9°) participants. It was further revealed that female Latin American dancers had significantly smaller lumbar lordosis values (3.7±3.1°) compared with female Standard (10.7±6.1°) and Ten Dance dancers (9.7±5.5°). CONCLUSIONS: The results of the present study suggest that smaller S-shaped vertebral curvatures of DanceSport athletes compared with track and field athletes are permanent changes rather than habitual.

ASSOCIATION OF SUBJECTIVE RATINGS TO OBJECTIVELY ASSESSED PHYSICAL ACTIVITY IN PUBERTAL BOYS WITH DIFFERING BMI.

The associations between subjective ratings and objectively measured moderate-to-vigorous physical activity (MVPA) were examined in normal, and overweight and obese, pubertal boys and compared with their parents' reports. In total, 224 boys (M age=12.2 yr.) completed the self-report questionnaire and wore an accelerometer for 7 consecutive days. Questionnaire-based indexes of physical activity (PA) were weakly associated with the accelerometer PA data. Correlations between subjective and objective assessments were significantly higher in overweight and obese groups. Parent reports predicted sedentary time better than boys' self-reports but no difference was found for MVPA. Future studies must consider that the source of rating, season, and weight status may be possible sources of confounding when using subjective assessments of PA.

Associations between Bone Mineral Characteristics and Serum Levels of Ghrelin and Peptide YY in Overweight Adolescent Boys.

BACKGROUND/AIMS: The role of ghrelin and peptide YY (PYY) in bone mineralization is not fully known. The aim of this study was to determine whether acylated and des-acyl ghrelin and PYY in addition to leptin are related to bone mineral density (BMD) in adolescent overweight boys (OWB) and normal-weight boys (NWB). PARTICIPANTS AND METHODS: Fifty- five OWB (BMI >85th percentile) and 154 NWB (BMI <85th percentile) aged 12-16 years participated in this study. Fasting serum acylated and des-acyl ghrelin, PYY, leptin, testosterone levels, total body (TB) and lumbar spine (LS) bone mineral content (BMC), and BMD were measured. TB BMC for height and TB and LS bone mineral apparent density (BMAD) were calculated. RESULTS: No differences were seen in acylated and des-acyl ghrelin or PYY levels, while the leptin levels were significantly higher in the OWB compared to the NWB. In the OWB, TB BMAD was positively correlated with acylated ghrelin and leptin, and TB BMC for height was positively correlated with PYY. In the OWB, the variability of TB BMD was determined by TB fat-free mass and des-acyl ghrelin, whereas the variability of TB BMAD was determined by leptin. CONCLUSIONS: Des-acyl ghrelin and PYY are involved in the bone mineralization process in puberty, and the impact can vary between normal and overweight subjects.

Maturity-related differences in moderate, vigorous, and moderate-to-vigorous physical activity in 10-14-year-old boys.

The goal of this study was to investigate differences in physical activity (PA) levels between early, average, and late maturing boys and the effect of chronological age, body mass index, and fat mass. PA was measured by accelerometry in 10-14-yr.-old boys (N=265) during seven consecutive days. Biological maturation groups (early, average, and late) were created. Average and late maturing boys had significantly higher moderate PA and moderate-to-vigorous PA compared to early maturing boys. Late maturers also had higher vigorous PA compared to early maturers. Differences in moderate PA and moderate-to-vigorous PA remained significant after controlling for chronological age; however, after controlling for Body Mass Index or fat mass the differences were no longer significant. Mean differences in PA between early, average, and late maturing boys are not independent of Body Mass Index or fat mass. Vigorous PA differences between maturity groups were not independent of chronological age.

Vigorous physical activity rather than sedentary behaviour predicts overweight and obesity in pubertal boys: a 2-year follow-up study.

AIM: Current physical activity (PA) recommendations indicate that children should get involved in 60 minutes of moderate-to-vigorous PA (MVPA), and should include vigorous-intensity PA at least three days a week. However, it is not known how many minutes of vigorous PA they should do. Using objective methods and a longitudinal design, this study aimed to examine how different PA intensities and sedentary behaviour relate with the risk of being overweight and obese during puberty over a two-year period. METHODS: A sample of 136 10-12-year-old (at baseline) boys participated. PA was measured by seven-day accelerometry. RESULTS: From MVPA thresholds, only 90 minutes per day of MVPA had important odds ratios (OR) for being overweight at baseline (OR=8.14, 95% confidence interval [CI] 1.03-64.04). A significant cut-off point for being overweight was indicated by 59 minutes per day of MVPA with at least 14 minutes per day of vigorous PA, and 55 minutes per day MVPA with at least 10 minutes per day of vigorous PA for those who were obese. Sedentary behaviour did not have any significant ORs for being overweight or obese. Subjects who did not meet the thresholds of 5 and 20 minutes per day of vigorous PA at baseline had an increased risk of being overweight (OR=4.05, 95% CI 1.41-11.59, and OR=4.14, 95% CI 1.35-12.73, respectively) and obese (OR=6.54, 95% CI 1.97-21.69, and OR=8.75, 95% CI 1.12-68.51, respectively) two years later. CONCLUSIONS: The results indicate that vigorous PA in particular predicts overweight and obesity in boys. They should aim to do at least 60 minutes per day of MVPA. These results contribute to the recommendations suggesting that a minimum of 15 minutes per day of vigorous PA is desired to reduce the risk of developing overweight/obesity in later puberty.

Osteocalcin is inversely associated with adiposity and leptin in adolescent boys.

BACKGROUND/AIMS: Recently, osteocalcin (OC), an osteoblast-derived hormone, has been found to correlate with adiposity, adipocytokines and insulin resistance in adults, but few studies have investigated this in children. The aim of this study was to investigate these associations in adolescent boys, for whom it is a time of significant bone mineral accrual, taking into account possible confounders related to adipose and bone tissues. PARTICIPANTS/METHODS: Participants were 141 adolescent boys (mean age 13.9±0.7 years), who were divided into tertiles according to OC levels. Across these groups, differences in total body fat mass (FM), body fat distribution, adiponectin, leptin and insulin resistance values were examined with relation to age, pubertal stage, daily energy and calcium intakes, and physical activity. RESULTS: Mean body mass index (BMI), FM, body fat% and leptin differed significantly between subjects in the three OC tertiles after adjustment for age, pubertal stage, energy and calcium intakes, and physical activity. There were no differences in fat free mass (FFM), bone mineral content, energy and calcium intakes, physical activity, adiponectin and insulin resistance values between study groups. For the entire cohort, mean serum OC was 130.2±45.2 ng/mL and was related to body mass, BMI, FM, body fat distribution and leptin. Circulating OC was not associated with FFM, daily energy and calcium intakes, physical activity, adiponectin or insulin resistance (insulin, glucose, homeostasis model assessment-insulin resistance) values. CONCLUSIONS: In male adolescents, OC is inversely related to body adiposity and leptin values, even after consideration of several factors that may affect bone and adipose tissues.

Tracking of physical activity in pubertal boys with different BMI over two-year period.

We examined the tracking of physical activity (PA) measured by accelerometers and subjective self- and parental reports in normal weight and overweight and obese pubertal boys over two-year period. In total, 156 boys with mean (±SD) age of 11.53 ± 0.76 at baseline and with mean age of 13.94 ± 0.74 at 2 year follow-up were studied. At baseline and approximately two years later, the boys completed self-report questionnaire and wore an accelerometer for seven consecutive days. On the basis of first year assessment's body mass index (BMI), the children were grouped as normal weight and overweight and obese groups according to BMI cut-offs. Tracking correlations of objectively measured PA and subjectively measured PA were fairly similar across the 12-14 year-old-boys weight groups over two year period. Tracking correlations of objectively measured PA and subjectively measured PA were not significantly different over two-year period between both BMI groups. The results of the study show that pubertal boys objectively measured PA decreased over two-year period and so the boys started to be less active in their pubertal period.

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). The limits of agreement analysis provided intervals from 7.5 mm (biceps) up to 30.14 mm (front thigh). Comparing Caliper and Lipometer results very low measurement agreement was found. The two methods provided very poor interchangeability.

Sedentary time has a negative influence on bone mineral parameters in peripubertal boys: a 1-year prospective study.

One of the key determinants of adult skeletal health is the maximization of bone mass during the growth period. Physical activity (PA) in combination with lean mass and fat mass contribute to a great extent to bone mineral accrual; however, PA changes significantly during puberty. The aim of the present study was to examine PA exposure relative to bone mass acquisition during a longer observation period. Daily PA was measured with 7-day accelerometry and bone mineral parameters by DXA in 11- to 13-year-old peripubertal boys (n = 169). Similar testing was done after 1 calendar year. Changes in sedentary time were negatively related to changes in whole-body bone mineral density (BMD), lumbar spine bone mineral content (BMC), lumbar spine bone area (BA), femoral neck (FN) BMD, and FN BMC (r > -0.157; p < 0.05). Sedentary time emerged as the main PA level in predicting changes in FN BMC (p = 0.027) and in combination with vigorous PA predicting changes in FN BMD (p < 0.024). In addition to the effect of body composition on the skeleton, increase in sedentary time emerged as one main physical activity predictor (in addition to vigorous PA) of bone mineral acquisition during a 12-month period in peripubertal boys.

Adipocytokine and ghrelin levels in relation to body composition in rhythmic gymnasts entering into puberty: a 3-year follow-up study.

The aim of this study was to describe longitudinal changes in body composition, leptin, adiponectin, and ghrelin over a 36-month period in prepubertal rhythmic gymnasts (RG) and their age-matched untrained controls (UC) entering into puberty. Thirty-five RG (8.0 ± 0.6 yrs) and 33 UC (8.2 ± 0.6 yrs) were followed at 12-month intervals for the next 3 years. Height, weight, pubertal stage, body composition, leptin, adiponectin, and ghrelin were measured at each time points. The pubertal development over the next 36 months was slower in the RG compared with UC. Leptin was increased in UC and remained unchanged in RG over 3-year study period (3.7 ± 3.6 vs. 0.2 ± 1.1 ng/ml; p < .05). In RG, baseline leptin was negatively correlated with the change in body fat percentage over a 36-month period (r = -0.34; p < .05). The change in adiponectin over the study period was negatively correlated with the change in BMI (r = -0.43; p < .05). RG had relative leptin deficiency per body fat mass. In conclusion, relatively high leptin concentration at the beginning of puberty may predict those girls who do not increase their body fat percentage through coming years and therefore may have increased risk for delayed puberty.

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).

Correlations of skinfold thicknesses and circumferences at exactly defined body sites with leptin in 10-12-year-old boys with different BMIs.

The aim of this study was to investigate the correlations of leptin with values of skinfold thicknesses and circumferences in 10-12-year-old boys (N = 248) and these correlations were additionally studied in boys with different BMI subgroups (normal N = 190, overweight N = 34 and obese N = 24). In total, 9 skinfolds and 13 circumferences were measured using the recommendations of ISAK. Fasting leptin concentrations were also determined. No significant differences emerged between the three subgroups in age and Tanner stage. Skinfold thicknesses, circumferences and leptin concentrations were significantly higher in overweight and obese groups. In the total group, the correlation (partial correlation, eliminating age and Tanner stage) between separate skinfold thicknesses and leptin was higher than r = 0.70. The sum of 9 skinfold thicknesses correlated significantly to leptin in all groups (r = 0.558-0.779). In the obese group, triceps, biceps and front thigh skinfold thicknesses did not correlate (p > 0.05) with leptin. In the total group, all measured circumferences correlated significantly to leptin concentration (r = 0.328-0.724). However, in the obese group, the measured circumferences did not correlate to leptin (p > 0.05). Waist-to-hip ratio correlated with leptin only in the total group of boys. It was concluded that as a rule, close correlations emerged between leptin and skinfold thicknesses and circumferences. The strongest correlation with leptin was found with the sum of 9 skinfolds and waist-to-hip ratio.

Role of physical activity in bone health in peripubertal boys.

BACKGROUND: The aim of the present cross-sectional study was to investigate the relationship of physical activity level to bone mineral parameters in 11-13-year-old boys. METHODS: In total, 264 boys, divided into normal weight (n = 154) and overweight (n = 110), participated in this study. Physical activity was measured via 7 day accelerometry and bone mineral parameters using dual-energy X-ray absorptiometry. RESULTS: In overweight boys, vigorous physical activity was associated with total bone mineral density (BMD), total bone mineral content (BMC), while moderate-vigorous physical activity MVPA was associated with femoral neck BMD. In normal weight boys, however, only vigorous physical activity was associated with femoral neck BMD. When the normal weight group was divided into tertiles according to MVPA, femoral neck BMD was higher in the highest tertile compared to the lowest tertile. No other significant differences were found in bone mineral parameters according to the tertiles of MVPA. CONCLUSIONS: In overweight peripubertal boys, physical activity is more associated with bone mineral parameters compared to normal weight subjects. In addition to vigorous physical activity, moderate physical activity has a significant impact on bone mineral parameters in overweight subjects.