High-intensity walking increases physical function, reduces BP in elderly

NEW YORK (Reuters Health) – High-intensity interval walking protects against age-associated increases in blood pressure and decreases in thigh muscle strength, and raises peak aerobic capacity as well, according to results of a study published in the July issue of Mayo Clinic Proceedings.

"The rapid growth in the elderly population in many countries has highlighted the importance of exercise training to decrease the likelihood of disability and age-associated disease, promote independence, and enhance quality of life," Dr. Hiroshi Nose and colleagues from Shinshu University Graduate School of Medicine, Matsumoto, Japan, write. "Moderately paced (about 6 km/h) walking, thought to protect against disability and age-associated diseases, has been widely recommended to middle-aged and older people. However, that pace may not be intense enough to increase peak aerobic capacity (Vo2peak) and other markers of physical fitness."

To address this issue, researchers assigned 60 men and 186 women (mean age 63 years) randomly to one of three groups: no walking training, moderate-intensity continuous walking training, and high-intensity interval walking training. They studied them for five months.

Subjects assigned to the moderate-intensity continuous walking training were instructed to walk at approximately 50% of their peak aerobic capacity for walking. A pedometer was used to verify that they took at least 8000 steps per day for 4 or more days per week.

Participants who were assigned to the high-intensity interval walking training group were monitored by accelerometry. These subjects were instructed to repeat five or more sets of 3-minute low-intensity walking at 40% of peak aerobic capacity for walking followed by a 3-minute high-intensity walking above 70% of peak aerobic capacity for walking per day for 4 or more days per week. The team measured isometric knee extension and flexion forces, peak aerobic capacity for cycling, and peak aerobic capacity for walking before and after training.

Of 25 men and 59 women in the no walking training group, nine and 37, respectively, met the target. Targets were met by eight of 16 men and 43 of 59 women in the moderate-intensity continuous walking training group, and by 11 of 19 men and 31 of 68 women in the high-intensity interval walking training group. In the high-intensity interval walking training group, knee extension increased by 13% and knee flexion increased by 17% (p < 0.001). Significant increases were also observed in Vo2peak for walking by 9% and for cycling by 8% (p < 0.001). All of these values were significantly higher than those in the no walking training group and the moderate-intensity continuous walking group.

"Systolic blood pressure and diastolic blood pressure for the high-intensity interval walking group decreased significantly by 9 mm Hg and 5 mm Hg, respectively (both p < 0.001), and the reduction in systolic blood pressure after training was significantly greater in the high-intensity interval walking group than in the no walking training group (p = 0.002) and in the moderate-intensity continuous walking group (p = 0.01)," Dr. Nose and colleagues write. "Moreover, systolic blood pressure decreased in 25 of 33 participants with increased Vo2peak for walking in the interval walking group (76%), suggesting a close relationship between systolic blood pressure and Vo2peak."

"Overall, the critical health benefit may be derived from the displacement of sedentariness by activity," Dr. James Levine, of the Mayo Clinic, Rochester, Minnesota, writes in an accompanying editorial. "The longer a person is active, the better, regardless of what form the activity takes."

"We are designed to walk all day long, and (this) article suggests that we should," Dr. Levine concludes.

Mayo Clin Proc 2007;82:803-811.