High-Intensity Walking Time Is a Key Determinant to Increase Physical Fitness and Improve Health Outcomes After Interval Walking Training in Middle-Aged and Older People

Abstract

Objective: To examine the effects of interval walking training (IWT) on the estimated peak aerobic capacity (eV˙O_2peak) and lifestyle-related disease (LSD) score while focusing on exercise intensity and volume in middle-aged and older people.

Participants and methods: Men and women (N=679; mean age, 65±7 SD years) completed 5-month IWT. Participants were instructed to repeat 5 or more sets of fast and slow walking for 3 minutes each at 70% or more and 40% eV˙O_2peak for walking, respectively, per day for 4 or more d/wk. This study was conducted from April 1, 2005, through February 29, 2008.

Results: Interval walking training increased eV˙O_2peak by 14% and decreased LSD score by 17% on average (P<.001). During 5-month IWT, fast and slow walking times were 88±65 SD and 100±86 min/wk, respectively, but varied among participants. We divided participants into approximately 10 bins for 6 minutes each of fast and slow walking times per week up to 60 min/wk, and above this time, approximately 8 bins for 30 or 60 minutes each of fast and slow walking up to the maximal time. We found that both eV˙O_2peak and LSD score improved as fast walking time per week increased up to 50 min/wk (R²=0.94; P<.001 for eV˙O_2peak; R²=0.51; P=.03 for LSDS) but plateaued above this time. In contrast, improvement in neither eV˙O_2peak nor LSDS was positively correlated with slow or total walking time per week. Multiple regression analyses confirmed that fast walking time per week was the major determinant of improvements in eV˙O_2peak (P<.001) and LSD score (P=.001).

Conclusion: High-intensity walking time during IWT is a key factor to increase eV˙O_2peak and decrease LSD score in middle-aged and older people.