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 ( $$\dot{V}$$ V ˙ O2GET), with a subjective feeling of 16–18 points of the Borg scale during fast walking in each condition. Before and after IWT, we measured $$\dot{V}$$ V ˙ O2GET, peak aerobic capacity ( $$\dot{V}$$ V ˙ O2peak) by graded walking and cycling tests on land and isometric knee extension (F EXT) and flexion (F FLX) forces.
Results
Before IWT, the $$\dot{V}$$ V ˙ O2GET for walking in water was 14 % higher and the heart rate (HR) at a given $$\dot{V}$$ V ˙ O2 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 $$\dot{V}$$ V ˙ O2peak and $$\dot{V}$$ V ˙ O2GET for cycling, F EXT and F FLX increased more in WG than in LG (all, P < 0.05).
Conclusion
Walking in water elevated $$\dot{V}$$ V ˙ O2GET 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.