In 2007, the United States faced a 60% prevalence of overweight and obesity, affecting people’s daily lives. This research aimed to compare the physical changes, body weight, and body composition in individuals who were physically inactive and overweight or obese before and after engaging in land-based running (LBR) and underwater treadmill training (UTM). 

The study involved 57 participants who were overweight, physically inactive, and randomly assigned to either LBR (29 participants) or UTM (28 participants) for 12 weeks (3 times/week). Participants consistently increased their calorie expenditure, starting from 250 – 500 kCal/session until week 6, where it remained at 500 kCal by week 12. After LBR and UTM training, significant improvements were observed in several aspects. The maximal oxygen consumption (VO 2max) increased significantly, while body weight, BMI (-0.56 ± 0.11 kg·m-2), % body fat and fat mass significantly decreased. Notably, the increase in leg lean body mass (leg LBM) was significant in the UTM group. Additionally, UTM reduced the impact on joints and muscles during exercise, resulting in a reduction in joint and muscle pain.