Target intensity and interval walking training in water to enhance physical fitness in middle-aged and older women: a randomised controlled study.

Purpose: To determine the target intensity for fast walking during interval walking training (IWT) in water for middle-aged and older people to enhance physical fitness.

Methods: Thirty-one women [59 ± 5 (SD) years old] were randomly divided into two groups: IWT on land (LG, N = 15) and in water (WG, N = 16). All subjects were instructed to perform ≥ 6 sets of fast and slow walking for 3 min each in a day, ≥ 4 days week(-1), for 8 weeks, at an intensity 35% higher than the oxygen consumption rate at the gas exchange threshold (VO2GET), with a subjective feeling of 16-18 points of the Borg scale during fast walking in each condition. Before and after IWT, we measured VO2GET, peak aerobic capacity (VO2peak) by graded walking and cycling tests on land and isometric knee extension (F EXT) and flexion (F FLX) forces.

Results: Before IWT, the VO2GET for walking in water was 14% higher and the heart rate (HR) at a given VO2 was ~10 beats min(-1) lower (P=0.001) than on land. During IWT, subjects in both groups performed IWT for ~4 days week(-1)(P > 0.9) with a 14% higher fast walking intensity in WG than in LG (P < 0.05). After IWT, the VO2peak and VO2GET for cycling, F EXT and F FLX increased more in WG than in LG (all, P < 0.05).

Conclusion: Walking in water elevated VO2GET and decreased HR at a given exercise intensity in middle-aged and older women, which enabled them to perform exercise at a higher metabolic rate than on land due to improved subjective feelings, which, for these subjects, resulted in greater gains in physical fitness.