This study was undertaken to evaluate the association of intensity or length of activity to coronary heart disease. The study population included 39,372 women aged 45 or older. The women were enrolled between 1992 and 1995 with a follow-up period until 1999. There were 244 cases of coronary heart disease during this time period. Vigorous exercise activities were associated with the lowest relative risk of coronary heart disease (RR= 0.63). Walking was also able to predict a lower risk in women who had no history of a vigorous exercise program or activity. Walking for up to 1 hour a week compared with no walking had a RR of 0.86. The RR for 1-1.5 hours and 2 or more hours were 0.49 and 0.48, respectively. They also analyzed the pace of the walk which ranged from 2-3 mph. They concluded that the length of time spent walking was the most important factor in reducing the risk, not the pace and that light to moderate exercise from walking is associated with a positive health benefit.

Comment: It is well accepted that exercise reduces the risk and occurrence of coronary heart disease. What is not absolutely certain is what is the appropriate level of exercise. Most exercise advice recommends a minimum of 20 minutes of exercise with a 5 minute warm up and 5 minute cool down phase 4 to 5 times per week. Although this study did not specify whether the exercise could be done in multiple blocks of time or all at once, most individuals could find 1 hour per week to walk, and at a reasonable pace of 2-3 mph. I find this study encouraging news for my patients who have a great deal of difficulty creating a lifestyle that includes regular exercise.