Purpose: No known previous research has been published to explore the efficacy of underwater treadmill (UTM) exercise training for the obese. Thus, the purpose of this study was to compare changes in physical fitness, body weight, and body composition in physically inactive, overweight, and obese adults after 12 wks of land treadmill (LTM) or UTM training.
Methods: Fifty-seven physically inactive, overweight, and obese men (n = 25) and women (n = 32) participated in this investigation. The mean ± SEM age, weight, body mass index (BMI), and V˙O2max upon entry were 44 ± 2 yr, 90.5 ± 2.4 kg, 30.5 ± 0.7 kg·m−2, and 27.1 ± 0.7 mL O2·kg−1·min−1, respectively. Subjects were randomly assigned to exercise three times per week for 12 wk on either LTM (n = 29) or UTM (n = 28) matched for intensity and volume. Session volume was progressively increased from 250 to 500 kcal per session by week 6 and remained at 500 kcal through week 12. Before and after training, V˙O2max was assessed by the Bruce treadmill protocol with open-circuit calorimetry, and body composition was assessed by dual-energy ray absorptiometry. Data were analyzed by a 2 (training) × 2 (exercise mode) × 2 (gender) ANOVA repeated across training (α = 0.05).
Results: Training responses were not different between genders. After either UTM or LTM training, V˙O2max was significantly increased (+3.6 ± 0.4 mL O2·kg−1·min−1), whereas body weight (−1.2 ± 0.3 kg), BMI (−0.56 ± 0.11 kg·m−2), body fat percentage (−1.3% ± 1.3%), and fat mass (−1.1 ± 0.3 kg) were significantly reduced (pooled means for UTM and LTM). Regional leg lean body mass (LBM) was significantly increased with both CTM and UTM (0.4 ± 0.3 and 0.8 ± 0.2 kg, respectively). An increase in total LBM approached significance with UTM training only (+0.6 ± 0.3 kg, P = 0.0599).
Conclusions: UTM and LTM training are equally capable of improving aerobic fitness and body composition in physically inactive overweight individuals, but UTM training may induce increases in LBM.