Effect of stride frequency on the energy cost of walking in obese teenagers

The aim of this study was to compare the energy cost of obese and non-obese teenagers while walking at their preferred speed and different stride frequencies. Twelve obese and twelve non-obese teenagers walked continuously on the treadmill at their most comfortable speed for 6 periods of 4 min each. Each period corresponded to a specific stride frequency: preferred (PSF), force-driven harmonic oscillator (FDHO), PSF + 10%, PSF + 20%, PSF - 10% and PSF 20%. Cardiorespiratory parameters were collected between the 3rd and 4th minute of each stage, and used to calculate the energy cost of walking (EC). The main results showed a significantly higher cost of walking expressed relative to lean body mass. In addition, a U-shaped relationship between EC and stride frequency was shown in both groups, with PSF and FDHO leading to a significantly lower value compared to all other frequencies. This showed first, that FDHO is a good predictor of PSF and minimal energy cost of walking in both groups, and second, that excess body fat does not affect the relationship between energy expenditure and stride frequency. Walking at lower or higher than preferred frequencies could be used as an exercise mode to promote weight loss in obese teenagers. (C) 2010 Elsevier B.V. All rights reserved.