Body Composition as a Mediator between Cardiorespiratory Fitness and Bone Mass during Growth

INTRODUCTION AND PURPOSE

To examine the effect of cardiorespiratory fitness (CRF) and muscle power output (MPO) on bone mass of prepubertal and pubertal children using lean mass (LM) and percentage of fat mass (%FM) as mediator variables. The hypothesis was that both LM and %FM would be independent mediators of the relationships during the sexual maturation period.

METHODS

We analyzed 200 children (88 boys and 112 girls [11.5 ± 2.0 yr]). Body composition was analyzed by bone densitometry, and indirect calorimetry and cycle ergometer were used to calculate V˙O2peak (mL·kg·min) and MPO (W) during an incremental exercise test. Sample was divided by pubertal status.

RESULTS

In the prepubertal group, LM and %FM acted independently as mediators in the relationship between bone mass and CRF or MPO (22%-25% for LM and 37%-50% for %FM, respectively). In pubertal children, LM acted as mediator at 37%.

CONCLUSIONS

Although the independent mediator role of LM and %FM in the associations between CRF or MPO and bone mass was present during the prepubertal stage, only LM remain its mediator role in these associations during the postpubertal period. Therefore, with growth and sexual maturation, the full effect of LM seems to increase, whereas the influence of %FM seems to disappear.

Effects of a 3-month vigorous physical activity intervention on eating behaviors and body composition in overweight and obese boys and girls

PURPOSE

This study aims to analyze the effects of a 3-month vigorous physical activity (VPA) intervention on eating behavior and body composition in overweight and obese children and adolescents.

METHODS

Forty-seven participants (7-16 years) took part in the study: 28 were assigned to the intervention group (IG) (10 boys and 18 girls) and 19 in a control group (CG) (8 boys and 11 girls). Body composition (dual-energy X-ray absorptiometry), anthropometrics (body mass, height, and body mass index (BMI)), and eating behavior traits (Three-Factor Eating Questionnaire-R21C) were determined before and after the VPA intervention.

RESULTS

A decrease in the percentage of body fat and BMI (-2.8% and -1.8%, respectively), and an increase in most lean mass variables were found in the IG (all p ≤ 0.05). In relation to the eating behavior traits, IG subjects showed a 14% reduction in the Emotional Eating score (p = 0.04), while Cognitive Restraint score did not change after the VPA intervention. The baseline factors of the questionnaire predicted changes in body mass and fat mass variables only in the CG.

CONCLUSION

A 3-month VPA intervention influenced eating behaviors of overweight or obese young, especially the Emotional Eating factor, in the presence of favorable body composition changes.

Frailty is associated with objectively assessed sedentary behaviour patterns in older adults: Evidence from the Toledo Study for Healthy Aging (TSHA)

OBJECTIVE

The aim of this study was to examine the association of sedentary behaviour patterns with frailty in older people.

SETTING

Clinical setting.

DESIGN

Cross-sectional, observational study.

PARTICIPANTS AND MEASUREMENTS

A triaxial accelerometer was used in a subsample from the Toledo Study for Healthy Aging (519 participants, 67-97 years) to assess several sedentary behaviour patterns including sedentary time per day, the number and duration (min) of breaks in sedentary time per day, and the proportion of the day spent in sedentary bouts of 10 minutes or more. Frailty was assessed using the Frailty Trait Scale (FTS). Regression analysis was used to ascertain the associations between sedentary behaviour patterns and frailty.

RESULTS

Sedentary time per day and the proportion of the day spent in sedentary bouts of 10 minutes or more, were positively associated with frailty in the study sample. Conversely, the time spent in breaks in sedentary time was negatively associated with frailty.

CONCLUSION

In summary, breaking up sedentary time and time spent in sedentary behaviour are associated with frailty in older people.

Influence of different sports on fat mass and lean mass in growing girls

PURPOSE

The aim of this study was to analyze and compare the effects of different sports (swimming, football, basketball, and handball) on fat mass and lean mass in prepubertal and pubertal girls.

METHODS

Two hundred girls (10.6 ± 1.5 years old, Tanner stages I-III) participated in the study and were divided into 5 groups: 40 swimmers, 40 football players, 40 basketball players, 40 handball players, and 40 controls. Fat and lean masses at whole body, arms, trunk, and legs were measured using dual-energy X-ray absorptiometry (DXA). Pubertal status was determined using Tanner test. Effects of different sports on fat and lean masses were assessed through analysis of covariance with height as covariates. Analyses were performed separately in 2 groups depending on the Tanner stage (prepubertal and pubertal).

RESULTS

The girls of the control group had less lean mass and more fat mass compared to the girls who play sports (p < 0.05). There were differences in body fat between sports. The swimmers and football players had less body fat (p < 0.05). On the other hand, handball players showed the highest values in lean mass (p < 0.05).

CONCLUSION

Impact sports (football, basketball, and handball) and low-impact sports (swimming) provide an appropriate development of lean mass in growing girls. We can conclude that people practicing sports at early ages ensure a lower fat mass and higher lean mass compared to those who do not practice. These results may be useful as a preventive method of adult obesity.

Higher bone mass in prepubertal and peripubertal female footballers

OBJECTIVES

The main aim of this study was to compare the bone mass of female football players with controls of different pubertal stages.

METHODS

Sixty five girls aged 8-14 years (10.14 ± 0.1, Tanner stages I-IV) participated in the study. Twenty participants were prepubertal (10 prepubertal control) and 45 peripubertal (15 peripubertal control). All footballers trained two days per week while the control group did not perform regular physical activity outside of school. Body composition was assessed by Dual-energy X-ray absorptiometry. Analysis of covariance was performed to evaluate differences in lean and bone masses.

RESULTS

Significant differences in lower-body extremities lean mass (LLM) between peripubertal groups were found (P < .05). Additionally, prepubertal footballers showed higher values of bone mineral content (BMC) at the femoral neck (P < .05) while peripubertal footballers exhibited enhanced BMC at the whole-body, trochanter and Wards triangle area. Bone mineral density (BMD) was higher in footballers compared to their non-active peers at the femoral neck and intertrochanter (P < .05, respectively) while in the peripubertal footballers higher BMD values were found in almost all of the studied body sites.

CONCLUSION

Female footballers showed higher bone and lean masses compared to control counterparts; these differences are already detectable at prepubertal ages and more consistent after pubertal spurt.

Influence of hard vs. soft ground surfaces on bone accretion in prepubertal footballers

Information regarding osteogenic effects of physical activity performed on different playing surfaces is scarce. A total of 42 children (9.2±0.2 years, Tanner stages I-II) participated in this study. 14 were playing on artificial turf soft ground (SG), 14 on a natural non-grass hard ground (HG) and 14 were assigned to the sedentary control group (C). Whole body and hip scans (dual energy X-ray absorptiometry), anthropometric variables (weight and height) and physical fitness (VO2max) were determined in all participants. Bone mineral content (BMC) values were higher in the SG group compared to the C group at the legs (209.75±5.11 g vs. 187.42±5.14 g, respectively), pelvis (122.72±4.27 g vs. 98.58±4.29 g respectively) and whole-body level (1 126.1±22.81 g vs. 1 035.34±22.92 g, respectively). The hard ground (HG) group also showed higher values in the majority of BMC variables compared to the C group. Additionally, bone mineral density (BMD) was significantly higher at all sites of the hip in both active groups compared to control (P<0.05). No differences between HG and SG were found. In summary, similar bone mass accretion is obtained by prepubescent footballers independently of the surface on which they practice football.