Author(s): MARI, L., D’ALLEVA, M., ZACCARON, S., STAFUZZA, J., GRANIERO, F., AZZINI, V., CIGALOTTO, A., CASASOLA, M., MOLINO, J., PASSARO, A., FIORI, F., MARINONI, M., DE MARTINO, M., ISOLA, M., PARPINEL, M., REJC, E., LAZZER, S., Institution: UNIVERSITY OF UDINE , Country: ITALY, Abstract-ID: 899

INTRODUCTION:
Obesity is primarily caused by unhealthy eating habits and insufficient physical activity [1]. Obesity is associated with reduced cardiorespiratory fitness, impaired exercise tolerance, and a diminished capacity to oxidise lipids at rest and during exercise [2, 3, 4]. Current guidelines from the American College of Sports Medicine (ACSM) state that programmes combining moderate and high intensity exercise are particularly effective in improving body composition and physical performance in this population [4]. Therefore, the present study aimed to investigate and compare the effects of polarised training (POL) and high intensity interval training (HIIT) on body composition, aerobic capacity, energy cost and substrate utilisation during walking.
METHODS:
Forty healthy men with obesity were recruited and randomly assigned into two groups. The HIIT group performed mainly high-intensity training, while the POL group performed mainly low-intensity training. All participants were tested at the beginning (T0), in the middle (T3), and at the end of the study (T6). Tests included measurements of anthropometric characteristics, body composition by BIA, maximal oxygen consumption (VO2max), energy cost and substrate utilisation during walking at 5 km h-1. Training sessions were based on participants actual ventilatory thresholds, with either an interval-based or a polarised weekly distribution.
RESULTS:
Body mass (BM) decreased in both POL and HIIT training groups from baseline to the end of the program (-2%, p=0.013 and -4%, p=0.003, respectively). Fat mass (kg) decreased only in the HIIT group by 6% (p=0.002). Both training groups significantly increased their VO2max (L min-1) by 14% (p=0.007) and 19.2% (p=0.022), respectively, and the maximal aerobic velocity by 13% and 19% (p=0.003, p<0.001, respectively). At the first and second ventilatory thresholds, VO2 and speed increased significantly from baseline to the end of the program in both training groups. The energy cost of transport (CoT, ml kg-1 m-1) at 5 km h-1 decreased in both groups by 16% and 9% (p=0.005, p=0.003), and the POL group showed a shift towards higher fat oxidation by 25% (p=0.016) and lower carbohydrate utilisation by 29% (p<0.001) compared to baseline.
CONCLUSION:
After 6 months of training, both groups decreased BM, improved speed at the ventilatory thresholds and reduced the cost of transport (CoT) during walking, accompanied in the POL group by a shift towards greater fat oxidation and lower carbohydrate utilisation. Overall, these results highlight the effectiveness of structured exercise programs in improving body composition and aerobic fitness, with each program approach providing different benefits.

References
(1) ‘Standard Italiani per la Cura dell’Obesità SIO-ADI’.
(2) ‘Obesity: identification, assessment and management Clinical guideline’, 2014.
(3) J. R. Berggren 2008.
(4) J. E. Donnelly et al; 2009.