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The aim of this study was to explore the relationship between maximal oxygen consumption (VO2 max) and bone mineral density (BMD) in a group of young Lebanese adults. Twenty women and 37 men whose ages range from 18 to 32 yr participated in this study. Informed written consent was obtained from the participants. Body weight and height were measured, and body mass index was calculated. VO2 max was determined by direct measurement while exercising on a bicycle ergometer (Siemens-Elema RE 820; Rodby Elektronik AB, Enhorna, Sweden). Whole body bone mineral content (WB BMC), whole body bone mineral density (WB BMD), lumbar spine BMD (L1-L4 BMD), total hip BMD (TH BMD), and femoral neck BMD (FN BMD) were measured by dual-energy X-ray absorptiometry. In women, VO2 max (expressed as L/mn) was positively correlated to WB BMC (r = 0.82; p < 0.001), WB BMD (r = 0.80; p < 0.001), L1-L4 BMD (r = 0.73; p < 0.001), TH BMD (r = 0.80; p < 0.001), and FN BMD (r = 0.85; p < 0.001). In men, VO2 max (expressed as L/mn) was positively correlated to WB BMC (r = 0.57; p < 0.001), WB BMD (r = 0.53; p < 0.001), L1-L4 BMD (r = 0.50; p < 0.001), TH BMD (r = 0.38; p < 0.01), and FN BMD (r = 0.30; p < 0.05). In both sexes, the positive associations between VO2 max and bone variables (BMC and BMD) remained significant after adjustment for age (p < 0.001). This study suggests that VO2 max (L/mn) is a positive determinant of BMC and BMD in young adults. Aerobic power seems to be a determinant of BMC and BMD in young adults., (Copyright © 2014 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

The aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight adolescent girls using hip structure analysis (HSA). This study included 64 postmenarcheal adolescent girls (14 obese, 21 overweight, and 29 normal weight). The 3 groups (obese, overweight, and normal weight) were matched for maturity (years since menarche). Body composition and bone mineral density (BMD) of whole body, lumbar spine, and proximal femur were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN) at its narrow neck (NN) region, the intertrochanteric (IT), and the femoral shaft (FS) by the HSA program. Cross-sectional area and section modulus were measured from hip BMD profiles. Total hip BMD and FN BMD were significantly higher in obese and overweight girls in comparison with normal-weight girls (p < 0.05). However, after adjusting for weight, using a one-way analysis of covariance, there were no significant differences among the 3 groups regarding HSA variables. This study suggests that in obese and overweight adolescent girls, axial strength and bending strength indices of the NN, IT, and FS are adapted to the increased body weight., (Copyright © 2013 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

Aim of the Study: The aim of this study was to compare bone mineral content (BMC), bone mineral density (BMD) and bone mineral apparent density (BMAD) in obese, overweight and normal weight adolescent boys., Methods & Results: This study included 23 obese, 19 overweight and 25 normal weight adolescents (aged 14-20 years) boys. The three groups (obese, overweight and normal weight) were matched for age and maturation index. Body composition, BMC and BMD were assessed by dual-energy X-ray absorptiometry (DXA). The expressions whole body (WB) BMC/height and WB BMD/height were used to adjust for WB bone size. BMAD was calculated for the WB. WB BMC, WB BMC/height, total hip (TH) BMD, femoral neck (FN) BMD and ultra distal (UD) radius BMD) were higher in obese and overweight boys in comparison to normal weight boys (p < 0.05). WB BMAD was lower in obese boys in comparison to overweight and normal weight boys (p < 0.05). After adjustment for either weight or lean mass, obese boys displayed lower WB BMC, WB BMC/height and WB BMD values in comparison to overweight and normal weight boys (p < 0.05)., Conclusion: This study suggests that WB BMC, WB BMC/height and WB BMD do not adapt to the increased body weight in obese adolescent boys.

The aim of this study was to assess the relationships of fatness and fitness with metabolic risk factors, including liver transaminases and inflammation in obese youth, taking in account gender, age, and pubertal stage. 241 children were studied (135 girls), age 11.9 +/- 2.2 years (x +/- SD), Body Mass Index z score 5.4 +/- 2.7. For girls, VO(2max) was significantly associated with insulin (P = .001), Insulin resistance (HOMA-IR) (P = .005), and ALT (P = .012); a relationship was displayed between fibrinogen and age and % fat mass (FM) (P = .008); for boys, relationships were found between VO(2max) and diastolic blood pressure and triglycerides; independent associations were also found between age and insulin, HOMA-IR and HDL cholesterol; fibrinogen and sedimentation rate were related (P

The aim of this study was to compare equivalence and agreement of physical activity output data collected by a Research Tri-axial accelerometer (R3T) during walking and running on a treadmill versus on land. Fifty healthy volunteers, 35 males (age 21.9 +/- 1.8 years) and 15 females (age 21.6 +/- 0.7 years), underwent a series of tests on a treadmill and on land with the order of testing administered randomly. Each participant walked for 10 min at 4 km x h(-1) and 6 km x h(-1), and ran at 8 km x h(-1) and 10 km x h(-1), with the same accelerometer. Analysis of output data was assessed by two statistical tests: the equivalence test and Bland and Altman method. Mean differences for walking were 41.2 +/- 129.8 counts per minute and -68.8 +/- 173.15 counts per minute at 4 km . h(-1) and km x h(-1), respectively. Mean differences for running were 19.1 +/- 253.20 counts per minute and 38.9 +/- 270.2 counts per minute at 8 km x h(-1) and 10 km x h(-1), respectively. The physical activity output data from the treadmill were higher by an average of 3.5% than the data collected on land. The differences obtained between the treadmill and on land were small and non-significant. The equivalence test showed that output data from the treadmill versus on land were equivalent (P < 0.05). The Bland and Altman method showed good agreement between the counts obtained on the treadmill and on land (P < 0.05). In conclusion, physical activity output data were similar as measured by the RT3 accelerometer on a treadmill and on land. The findings suggest that the RT3 may be used in a laboratory and extrapolated to data obtained on land.

In this study, we examined fat oxidation rates during exercise in obese pubescent boys. Three groups of pubescent boys (16 pre-pubescent, Tanner's stage I; 16 pubescent, Tanner's stage III; and 14 post-pubescent, Tanner's stage V) performed a graded test on a leg cycle ergometer. The first step of the test was fixed at 30 W and power was gradually increased by 20 W every 3.5 min. Oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)) were determined as the means of measurements during the last 30 s of each step, which allowed us to calculate fat oxidation rates versus exercise intensity. Between 20 and 50% of peak oxygen consumption (VO(2peak)), fat oxidation rate in relative values (mg . min(-1) . kg FFM(-1)) decreased continuously with pubertal development. In the same way, the maximum rate of fat oxidation occurred at a lower percentage of VO(2peak) (pre-pubescent: 49.47 +/- 1.62%; pubescent: 47.43 +/- 1.26%; post-pubescent: 45.00 +/- 0.97%). Our results confirm that puberty is responsible for a decrease in fat free mass capacities to use fat during exercise. The results suggest that post-pubescent obese boys need to practise physical activity at a lower intensity than pre-pubescent boys to enhance lipolysis and diminish adipose tissue and the consequences of obesity.

Aims: To assess the efficiency of an ambulatory weight management programme of pediatric obesity, including 1 gymnastic session per week, on body composition and physical fitness (max)., Subjects: Fifteen adolescents participated in the 9-month intervention. BMI and fitness and physical activity assessed by a questionnaire were evaluated at baseline, and after intervention., Results: Prepubescent subjects (N=6): no significant change of BMI, body composition, nor max. Pubescent subjects: significant decrease of BMI, and z score BMI, and % fat mass, increase of fat free mass. Activity questionnaire: non-significant trend to decreased TV watching, significant increase in practice of physical activity during weekend., Conclusion: A modest increase in physical practice, included in the dietary-behavioural management of adolescent obesity, is able to improve overweight and physical fitness.

The aim of the present study was to investigate effect of puberty on substrate oxidation rates using a graded exercise test to exhaustion. Two groups of obese adolescent males (34 prepubertal: body mass index (BMI) = 25,94 +/- 2,63; Z-score = 4,43 +/- 1,83; and 26 postpubertal: BMI = 31,14 +/- 4,88; Z-score = 5,264 +/- 1,76) performed an exercise test on a cycle ergometer. The test consisted in a series of graded exercises on a cycle ergometer. Stage duration was 3 min 30 s. Fat and carbohydrate rates were calculated during the last 30 s of each stage using stoichiometric equations, and this permitted us to calculate substrate oxidation according to exercise intensity. Lipid oxidation rates are significantly higher in the postpubertal group. When the fat oxidation rates are reported relative to fat free mass, fat oxidation rates are higher in the prepubertal group. Puberty decreases significantly the capacity of fat free mass to oxidize fat for a same level of exercise.

Lipid peroxidation stress induced by iron supplementation can contribute to the induction of gut lesions. Intensive sports lead to ischemia reperfusion, which increases free radical production. Athletes frequently use heavy iron supplementation, whose effects are unknown. On the other hand, milk proteins have in vitro antioxidant properties, which could counteract these potential side effects. The main aims of the study were: (1) to demonstrate the effects of combined exercise training (ET) and iron overload on antioxidant status; (2) to assess the protective properties of casein in vivo; (3) to study the mechanisms involved in an in vitro model. Antioxidant status was assessed by measuring the activity of antioxidant enzymes (superoxide dismutase (SOD); glutathione peroxidase (GSH-Px)), and on the onset of aberrant crypts (AC) in colon, which can be induced by lipid peroxidation. At day 30, all ET animals showed an increase in the activity of antioxidant enzymes, in iron concentration in colon mucosa and liver and in the number of AC compared to untrained rats. It was found that Casein's milk protein supplementation significantly reduced these parameters. Additional information on protective effect of casein was provided by measuring the extent of TBARS formation during iron/ascorbate-induced oxidation of liposomes. Free casein and casein bound to iron were found to significantly reduce iron-induced lipid peroxidation. The results of the overall study suggest that Iron supplementation during intensive sport training would decrease anti-oxidant status. Dietary milk protein supplementation could at least partly prevent occurrence of deleterious effects to tissue induced by iron overload.