Previous studies have shown that low-intensity resistance training with restricted muscular venous blood flow (KAATSU) causes muscle hypertrophy and strength gain. To investigate the effects of daily physical activity combined with KAATSU, we examined the acute and chronic effects of walk training with and without KAATSU on MRI-measured muscle size and maximum dynamic (1-RM) and isometric strength, along with blood hormonal parameters. Nine men performed KAATSU-walk training and 9 men performed walk training alone (Control-walk). Training was conducted 2 times/day, 6 days/week for 3 weeks using 5 sets of 2-min bout (treadmill speed at 50 m/min), with a 1-min rest between bouts. Mean oxygen uptake (VO₂) during KAATSU-walk and Control-walk exercise were 19.5 ± 3.6% and 17.2 ± 3.1% of treadmill-determined VO₂ max, respectively. Serum growth hormone was elevated (P<0.01) after acute KAATSU-walk exercise, but not in Control-walk exercise. MRI-measured thigh muscle cross-sectional area and muscle volume increased 4~7%, and 1-RM and maximum isometric strength increased 8~10% in the KAATSU-walk group. There was no change in muscle size and dynamic and isometric strength in the Control-walk group. Indicators of muscle damage (creatine kinase and myoglobin) and resting anabolic hormones did not change in both groups. The results suggest that the combination of leg muscle blood flow restriction with slow-walk training induces muscle hypertrophy and strength gain despite the minimal level of exercise intensity. KAATSU-walk training may be a potentially useful method for promoting muscle hypertrophy covering in a wide range of the population, including the frail and elderly.