Less-intense workouts may be less effective

NEW YORK, Feb 14 (Reuters) Low-intensity endurance exercise is not as effective as moderate intensity endurance exercise for promoting fitness, German researchers found in a controlled study.

Low-intensity workout recommendations ''might be appropriate for those who have impaired health or cardiac disease, but not for healthy middle aged subjects, like the majority of those who come and ask for preventive exercise'' recommendations, Dr Tim Meyer of the University of Saarland in Saarbrucken, the study's lead author, told Reuters Health.

Less-strenuous exercise has been promoted in recent years, and is often touted as being more efficient for burning fat, Meyer noted. While low-intensity exercise has indeed been proven to reduce mortality and help prevent heart disease, it is less clear whether easier workouts can build fitness as efficiently.

To investigate, Meyer and colleagues randomized 39 healthy people to a control group who did not exercise, a group who exercised at moderate intensity 5 days a week for 30 minutes, and a low-intensity group instructed to keep their heart rate at a level about 15 beats per minute, which is lower than the rate prescribed for the moderate intensity group. The low-intensity group worked out somewhat longer so they would burn an equal number of calories.

The low-intensity group worked out at an average of 71 per cent of their maximum heart rate, while the moderate intensity group got their heart rates up to 79 per cent of the maximum. From 55 per cent to 65 per cent of maximum heart rate intensity is generally considered to be the threshold that must be reached in order for endurance training to be effective.

After 12 weeks, the moderate intensity group showed slightly greater gains in endurance, Meyer and his team found.

Specifically, the moderate exercisers were able to use oxygen more efficiently, while they showed greater reductions in heart rate during exercise.

Based on the findings, Meyer said, healthy people with no heart problems should shoot for reaching at least 80 per cent of their maximum heart rate during endurance workouts. ''If you have a healthy cardio-circulatory system, there is no reason to avoid intense exercise.'' SOURCE: International Journal of Sports Medicine, January 2007.

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