Frequency and duration of vigorous physical activity bouts are associated with adolescent boys' bone mineral status: A cross-sectional study.

PURPOSE: Vigorous physical activity (VPA) has been proven to promote osteogenesis in adolescents; however the specifics of the optimal pattern of frequency and duration of VPA are unknown. The main goal of the present study was to analyze the associations of different length of VPA bouts with bone health. METHODS: 180 healthy male adolescents (11-13 years) had their bone mineral content and density assessed by dual-energy X-ray absorptiometry scans at the whole body, femoral neck (FN) and lumbar spine and their physical activity measured by an accelerometer during one week. RESULTS: VPA was the intensity with the strongest associations with bone mineral parameters especially at the FN. Subjects whose longest VPA bout was 5 min or above had higher FN bone mineral density (BMD) than those who did not complete any 5-min bout and these differences were greater with participants who reached 15 consecutive minutes of VPA (>15': 0.977 ±â€¯0.020 g/cm2; 5'-15': 0.907 ±â€¯0.009 g/cm2; <5': 0.876 ±â€¯0.009 g/cm2; all p < 0.05). When comparing the relevance of VPA bouts and volume of physical activity, the group with low volume and having a VPA bout had better FN BMD compared to the group with high volume but no VPA bout. Additionally, the group with both high volume and VPA bout showed better FN BMD than the rest of the groups. CONCLUSIONS: VPA may be the most effective activity intensity to improve bone mineral density and content of adolescent boys, with greater benefits if VPA periods either long or frequent.

Associations of Accumulated Time in Bouts of Sedentary Behavior and Moderate-to-Vigorous Physical Activity With Cardiometabolic Health in 10- to 13-Year-Old Boys.

BACKGROUND: Little is known about the impact of sedentary and moderate-to-vigorous physical activity (MVPA) bouts on cardiometabolic health. The aim was to examine how the accumulation of bouts of sedentary time and MVPA associates to cardiometabolic health in children independently of total sedentary and MVPA time. METHODS: In a cross-sectional study with 123 boys (10-13 y), sedentary and MVPA bouts were determined using 7-day accelerometry. Each bout was compared with cardiometabolic risk factors and with the risk score that was calculated using standardized values of body mass index, waist circumference, homeostasis model assessment for insulin resistance, triglycerides, and total cholesterol/high-density cholesterol ratio. RESULTS: Time in 10- to 14-minute sedentary bouts was negatively associated with continuous cardiometabolic risk score in weekdays and weekend days and with triglycerides in a weekend (P < .05). Time accumulated in ≥30-minute sedentary bouts was associated with higher insulin and homeostasis model assessment for insulin resistance values in weekend (P < .05). Weekday total MVPA and time accumulated in ≥10-minute MVPA bouts were negatively associated with continuous cardiometabolic risk score and body mass index in weekdays (P < .05). No associations were found between total sedentary time and metabolic health. CONCLUSION: Significant associations between sedentary and MVPA bouts with cardiometabolic risk factors suggest the need of the more detailed analysis for sedentary behavior and its effects on health risks.

Longitudinal changes in bone-testis axis and their associations with insulin resistance in 11- to 12-year-old boys.

PURPOSE: Associations between osteocalcin (OCN), an osteoblast-specific hormone, and different markers of energy metabolism and insulin resistance have been reported in adults, but few studies have investigated this in children. The aim of the current study was to investigate serum OCN levels during pubertal development in normal weight (NW) and overweight (OW) boys, and to evaluate possible associations of OCN with body composition, testosterone, insulin resistance and adipocytokine values during puberty. METHODS: Ninety 11- to 12-year-old boys were investigated at 12-month intervals over the next 2years. Boys were divided by their BMI into NW (n=60) and OW (n=30) groups. Serum OCN, testosterone, leptin, adiponectin, insulin, HOMA-IR score, and body composition were measured. RESULTS: Pubertal development over the 2-year period was similar in both groups. Serum OCN was not different at the beginning of the study and increased similarly in both groups. However, at the end of the study, NW had higher OCN than OW (142.9±5.2 vs. 124.0±7.4ng/ml; p<0.05). OW had higher leptin, insulin and HOMA-IR compared to NW, and these differences remained significant through the 2-year period. Testosterone, insulin and HOMA-IR increased through the study period in both groups. In multiple regression analyses increment in OCN was associated with the increase in testosterone in NW (p<0.001) and OW (p=0.049) boys. Increment in OCN was also associated with the increase in insulin (p=0.019) and HOMA-IR (p=0.012) over the 2-year period in NW boys. CONCLUSION: Serum OCN concentration increases in puberty and the increment is positively associated with the rise in testosterone level in both NW and OW boys. The positive association between the rise in OCN and insulin in NW boys would suggest that OCN may have a role in the development of insulin resistance.

The Impact of Physical Activity on Serum Inflammatory Markers in Overweight Pubertal Boys: 24-Month Follow-Up Study.

PURPOSE: To investigate the differences in the pattern of changes in serum inflammatory cytokines measured annually over a 24-month period, between less active and more active overweight boys. PARTICIPANTS/METHODS: In total, 25 pubertal overweight boys were divided by their moderate to vigorous physical activity (MVPA) levels into 2 groups: less active group (LAG; n = 10; MVPA < 60 min/d) and more active group (MAG; n = 15; MVPA > 60 min/d). Physical activity was measured by 7-day accelerometry. Serum concentration of 13 inflammatory cytokines [interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, IL-1α, IL-1ß, vascular endothelial growth factor, interferon-γ, tumor necrosis factor-α, monocyte chemotactic protein-1, epidermal growth factor, and C-reactive protein] was measured at baseline (T0), after 12 months (T1), and after 24 months (T2) from fasting blood samples. RESULTS: Serum IL-6 level was significantly higher [LAG: 1.27 (0.86, 1.98) pg/mL; MAG: 0.80 (0.52, 0.84) pg/mL] at T0 and IL-8 level [LAG: 10.26 (8.80, 11.64) pg/mL; MAG: 7.42 (6.10, 9.54) pg/mL] at T2 in LAG compared with MAG. The changes over the study period varied between different inflammatory markers. None of the slopes of any measured markers were statistically different between the LAG and MAG, although the slopes of interferon-γ and IL-10 tended to be different between the groups. CONCLUSIONS: The pattern of changes over the study period varied between different inflammatory markers, but these changes were not different between the MVPA groups. More longitudinal studies are needed to investigate whether IL-6, IL-8, IL-10, and interferon-γ would be the choice of inflammatory markers to study the associations between obesity and physical activity in future.

Extensive BMI Gain in Puberty is Associated with Lower Increments in Bone Mineral Density in Estonian Boys with Overweight and Obesity: A 3-Year Longitudinal Study.

The aim of this 3-year prospective study was to examine changes in bone mineral characteristics during pubertal maturation in boys with different BMI values at the beginning of puberty and with different BMI increments during puberty. 26 boys with overweight and obesity (OWB) and 29 normal weight boys (NWB) were studied yearly for 3 years from the age of 11 years to measure the changes in different bone mineral characteristics. The OWB group was further divided into two subgroups according to extensive or non-extensive BMI increment during 3-year period. OWB had higher (P < 0.01) baseline total body (TB) bone mineral density (BMD), TB bone mineral content (BMC), TB BMC for height, lumbar spine (LS) BMD, and LS BMC compared to NWB. Throughout the study period, OWB gained more TB BMD (P = 0.0001), TB BMC (P = 0.0048), TB BMC for height (P = 0.0124), LS BMD (P = 0.0029), and LS BMC (P = 0.0022) compared to NWB. Also during the study period, TB BMD (P = 0.0065), TB BMC (P = 0.0141), TB BMC for height (P = 0.0199), LS BMD (P = 0.0066), LS apparent volumetric BMD (BMAD) (P = 0.0075), and LS BMC (P = 0.017) increased significantly less in those OWB whose BMI increased more extensively. Extensive BMI gain is associated with lower increments in bone mineral characteristics in boys with overweight and obesity. Unfavorable increment in total body fat mass and percentage during pubertal years could be one reason for that.

Changes in inflammatory markers in estonian pubertal boys with different BMI values and increments: A 3-Year Follow-Up Study.

OBJECTIVE: Serum inflammatory markers could help to identify those boys with overweight (OWB) who gain weight more extensively during puberty. This study aimed to examine the longitudinal changes in different serum inflammatory markers through puberty in boys with different BMI values and increments. METHODS: Twenty-six OWB and 29 normal-weight boys (NWB) were followed yearly for 3 years to measure changes in BMI and serum concentrations of 12 inflammatory markers. RESULTS: OWB had higher (P < 0.033) baseline interleukin (IL)-6, IL-8, interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and IL-1α concentrations in comparison with NWB. Over the 3-year period, IFN-γ (P = 0.0001) and TNF-α (P = 0.0042) decreased more in OWB compared to NWB. Serum IL-8, monocyte chemoattractant protein (MCP)-1, and leptin increased further in those OWB who gained BMI more extensively through puberty compared to OWB who gained weight at slower rates (P < 0.033). CONCLUSIONS: Serum IFN-γ and TNF-α levels decreased more during pubertal years in OWB compared to NWB, indicating that pubertal maturation itself may have a favorable impact on the inflammation of obesity. Serum IL-8, MCP-1, and leptin could help to identify OWB who gain BMI more extensively during pubertal years.

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).

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.

Diet misreporting can be corrected: confirmation of the association between energy intake and fat-free mass in adolescents.

Subjective energy intake (sEI) is often misreported, providing unreliable estimates of energy consumed. Therefore, relating sEI data to health outcomes is difficult. Recently, Börnhorst et al. compared various methods to correct sEI-based energy intake estimates. They criticised approaches that categorise participants as under-reporters, plausible reporters and over-reporters based on the sEI:total energy expenditure (TEE) ratio, and thereafter use these categories as statistical covariates or exclusion criteria. Instead, they recommended using external predictors of sEI misreporting as statistical covariates. We sought to confirm and extend these findings. Using a sample of 190 adolescent boys (mean age=14), we demonstrated that dual-energy X-ray absorptiometry-measured fat-free mass is strongly associated with objective energy intake data (onsite weighted breakfast), but the association with sEI (previous 3-d dietary interview) is weak. Comparing sEI with TEE revealed that sEI was mostly under-reported (74 %). Interestingly, statistically controlling for dietary reporting groups or restricting samples to plausible reporters created a stronger-than-expected association between fat-free mass and sEI. However, the association was an artifact caused by selection bias - that is, data re-sampling and simulations showed that these methods overestimated the effect size because fat-free mass was related to sEI both directly and indirectly via TEE. A more realistic association between sEI and fat-free mass was obtained when the model included common predictors of misreporting (e.g. BMI, restraint). To conclude, restricting sEI data only to plausible reporters can cause selection bias and inflated associations in later analyses. Therefore, we further support statistically correcting sEI data in nutritional analyses. The script for running simulations is provided.

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.

Short-term creatine supplementation has no impact on upper-body anaerobic power in trained wrestlers.

BACKGROUND: Creatine (CR) is considered an effective nutritional supplement having ergogenic effects, which appears more pronounced in upper-body compared to lower-body exercise. Nevertheless, results regarding the impact of CR loading on repeated high-intensity arm-cranking exercise are scarce and in some cases conflicting. Interestingly, few of the conducted studies have structured their research designs to mimic real world sporting events. Therefore, our purpose was to address the hypothesis that CR ingestion would increase anaerobic power output in consecutive upper-body intermittent sprint performance (UBISP) tests designed to simulate wrestling matches on a competition-day. METHODS: In a double-blind, placebo-controlled, parallel-group study, 20 trained wrestlers were assigned to either placebo or CR supplemented group (0.3 g ∙ kg(-1) of body mass per day). Four 6-min UBISP tests interspersed with 30-min recovery periods were performed before (trial 1) and after 5 days (trial 2) of supplementation. Each test consisted of six 15-s periods of arm-cranking at maximal executable cadence against resistance of 0.04 kg ∙ kg(-1) body mass interspersed with 40-s unloaded easy cranking periods and 5-s acceleration intervals (T1-T4). Mean power (MP), peak power (PP), fatigue index and heart rate parameters were measured during UBISP tests. Also, body weight and hydration status were assessed. Principle measures were statistical analysed with mixed-model ANOVAs. RESULTS: Mean individual CR consumption in the CR group was 24.8 ± 2.5 g ∙ d(-1). No significant (P > 0.05) differences occurred in body mass or hydration status indices between the groups or across trials. MP, PP and fatigue index responses were unaffected by supplementation; although, a significant reduction in MP and PP did occurred from T1 to T4 in both trial 1 and 2 (P < 0.001). Overall heart rate responses in the tests tended to be higher in the CR than PLC group (P < 0.05); but, trends in responses in trials and tests were comparable (P > 0.05). CONCLUSION: These results suggest that 5-day CR supplementation has no impact on upper-body muscle anaerobic power output in consecutive UBISP anaerobic tests mimicking wrestling matches on a competition day.

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.