Author(s): KANATANI, K., TAKAGI, T., KAWABATA, T., Institution: ENVIROMENT PHYSIOLOGY FOR EXERCISE, Country: JAPAN, Abstract-ID: 1904

INTRODUCTION:
Interval walking training (IWT) improves fitness, muscle strength, and blood pressure in older adults within several months, but evidence on long‑term adaptations beyond 6 months is limited. This study examined the 12‑month effects of IWT on peak aerobic capacity (VO₂peak), lower‑limb muscle strength, and blood pressure, focusing on whether adaptations continue or plateau after exercise‑intensity readjustment at 6 months.
METHODS:
Thirty‑three community‑dwelling older adults (2 men, 31 women; 73±5 years) completed a 12‑month IWT program. IWT consisted of alternating 3‑min fast walking at 70% of maximal capacity and 3‑min normal walking, performed for 30 min/day on ~4 days/week using an activity monitor that provided real‑time feedback. VO₂peak was assessed at baseline, 6 months, and 12 months using a validated 3‑stage step‑up walking test. Exercise intensity was readjusted at 6 months. Knee extensor/flexor strength and resting blood pressure were measured monthly. VO₂peak was analyzed using repeated‑measures ANOVA, and monthly variables using linear mixed models with estimated marginal means.

RESULTS:
VO₂peak increased significantly from baseline (3.77±1.13 mL/kg/min) to 6 months (4.26±1.11) and 12 months (4.35±1.26) (p<0.001), with no significant difference between 6 and 12 months, indicating maintained improvement after intensity readjustment. Knee extensor strength increased from the first month and flexor strength from the third month, with both maintained thereafter (extensor: +5.5 kgf; flexor: +2.2 kgf at 12 months). No additional gains were observed between 6 and 12 months. Systolic blood pressure decreased significantly from the third month and remained reduced through 12 months. Diastolic blood pressure showed continuous improvement, with a significant additional reduction from 6 to 12 months (−1.97 mmHg, p<0.001). Fast‑walking duration remained stable, whereas total exercise time increased after the second month, indicating high adherence.
CONCLUSION:
Twelve months of IWT resulted in sustained improvements in cardiorespiratory fitness, lower limb muscle strength, and resting blood pressure in older adults. Knee extensor and flexor muscle strength increased during the early intervention period and were successfully maintained thereafter even following exercise intensity readjustment at 6 months. VO₂peak improved by 6 months and remained elevated through 12 months. Both systolic and diastolic blood pressure decreased during the early phase and maintained reduced levels throughout the intervention period. These results demonstrate that long-term IWT is effective for not only achieving initial improvements but also maintaining enhanced physical fitness, muscle strength, and cardiovascular health over an extended period. The consistent fast-walking duration throughout the 12-month intervention suggests that maintaining a steady level of high-intensity walking stimulus is sufficient to preserve the health benefits gained from IWT in older adults.