The influence of physical training modalities on basal metabolic rate and leptin on obese adolescent boys.
The aim of this study was to investigate the effects of physical training modalities on basal metabolic rate, cardiovascular fitness and serum leptin level in obese adolescent boys. Sixteen obese adolescent boys (age: 16.81 +- 0.91 years) were randomly assigned to either resistance (RTG) (n=8) or endurance (ETG) (n=8) training and followed the respective training programmes for six months (3 days/wk, 60 min/day). Leptin, basal metabolism rate (BMR), and maximum oxygen consumption (VO2max) were evaluated at the beginning and end of the intervention. After the training period, Leptin was decreased and VO2max was increased in both groups (p<0.05), whereas BMR was statistically increased only in ETG (p30 min of resting in a supine position on a bed, in absolute quietness and at thermal neutrality. Oxygen consumption and carbon dioxide production were measured every minute for 30 minutes by a calibrated Ergospirometer (ZANA(r) 680 USB, ZANMessgeraete, Oberthulba, Germany). BMR was calculated using Weir's equation.5
The participants were asked to complete a specific graded exercise treadmill test (Bruce protocol) on a RAM 770 treadmill (Model 770 M, RAM Medical and Industrial Instruments and Supply, Padova, Italy). Total run time in minutes was converted to oxygen consumption values according to Bruce protocol algorithm. Both groups attended their own training programme for six months for three sessions per week (3 days/wk, 60 min/day). Exercise intensity of was controlled by Polar telemetric pulse meter (Polar S625x, Polar Electro Oy, Finland). For the endurance exercise prescription, exercise intensity was designed for an intensity of 50% - 60% for the first two months, 60% - 70% for the third and fourth months, and for the fifth and sixth months at 70% - 75% of the maximum heart rate.
Accordingly, the appropriate resistance exercise programme for each individual was established by calculating 50% - 60% of 1-RM (repetition maximum) during the first two months, 60% - 70% of 1-RM during the second two months, and 70% - 75% of 1-RM during the last two months. A dietitian provided counseling and recommendations on balanced nutrition but a structured diet programme was not implemented throughout the study. The nonparametric Wilcoxon matched-pairs signed test was used to assess the significance of the differences between the mean values of variables in the groups.
All participants were obese according to the international age-related cut-off points for childhood obesity.4 BMI decreased significantly (p<0.05) between pre-and post-tests for the RTG group. Percent body fat decreased significantly (p0.05) (Table-1). Both in the ETG and RTG, there were significant differences between pre-and post-test values for leptin (p<0.05). BMR increased significantly (p<0.05) by 14.75% in the ETG, but not in the RTG group (9.8%). The post-test values for VO2max increased significantly in both groups (p<0.05) (Table-2).
Our findings are in agreement with previous reports presented by Ackel-D'Elia et al,6 who demonstrated that leptin levels were reduced by both endurance training and endurance training combined with strength training in obese adolescents. In contradiction, Barbeau et al7 and Lau et al8 did not observe any weight loss and decrease in leptin levels after physical training. These controversial findings may be due to different patterns and durations of exercises, participants' nutritional status, physical activity or the circadian rhythm of leptin. Regarding cardiovascular fitness, both of our 6-month training interventions were able to significantly increase absolute and relative VO2max. The higher the cardiovascular fitness, the more protected one is against obesity risk factors. In this way, Aires et al9 reinforce the importance of interventions that increase VO2max in obese adolescents.
The resistance exercise protocol was not able to improve BMR, while the endurance exercise proved to be effective in increasing BMR. This is supported by the findings of Alberta et al.10 who showed that 6 months of aerobic, resistance, or combined training with modest dietary restriction did not increase BMR compared with diet only in adolescents with obesity.
Our results indicate that both endurance and resistance exercises without caloric restriction were effective in reducing body fat percentage, increasing VO2max and decreasing leptin levels in obese adolescent boys. Basal metabolic rate increased only by endurance training.
Disclosure: This study was financially supported by the Marmara University Scientific Research Projects Committee (project no: SAG-C-DRP-04609-0145).
Conflicts of Interest: None of the authors have any potential conflicts of interest associated with this research.
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|Publication:||Journal of Pakistan Medical Association|
|Date:||Jun 30, 2018|
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