The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Does exercise intensity matter?

Written by
Sue Beckham, PhD
Posted in
Move more

Monday, Jul 18, 2011

Is vigorous exercise better than moderate intensity exercise as long as you achieve the recommended number of minutes per week based on intensity? Recall that for health benefits, the American College of Sports Medicine (ACSM) and American Heart Association (AHA) recommend 150 minutes/week of moderate intensity exercise or 75 minutes/week of vigorous exercise to achieve health benefits. The most current research on this topic was recently summarized in ACSM’s Position Stand1, Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise, which was published in Medicine and Science in Sports and Exercise. 

Many of the studies investigating the effect of vigorous vs. moderate intensity exercise on a variety of risk factors did not control for volume (calorie expenditure) of exercise. Recall that volume of exercise, which is often measured in calories expended, depends on the intensity, duration, and frequency of each exercise bout. To study the impact of exercise intensity only on risk factors, the overall volume of exercise for both the moderate and vigorous intensity study groups should be equal. For example, vigorous intensity exercise burns more total calories per minute than moderate intensity for the same duration. This could lead to additional benefits related to calorie burning and not exercise intensity. 

A review of only the well designed studies which controlled for exercise volume showed that vigorous exercise produced greater increases in aerobic capacity than moderate intensity exercise. Vigorous exercise has also been shown to provide greater reductions in cardiovascular disease and premature death. A study by L. DiPietro and her colleagues2 reported significant improvements in insulin sensitivity in nonobese, older women who participated in vigorous intensity but not moderate intensity exercise when both groups expended 300 calories per exercise session four days per week. This suggests that if time is limited that vigorous exercise may provide more benefits in regards to improving insulin sensitivity. However, this should be interpreted with caution as moderate intensity exercise may be as effective as vigorous exercise if performed more frequently (daily) or for longer durations.

With regard to HDL (good) cholesterol, LDL (bad) cholesterol, and triglyceride (blood fats) levels, the few studies that controlled for volume suggest that vigorous exercise does not provide greater benefits than moderate intensity exercise in improving these risk factors. Unfortunately, there is not enough research on blood pressure which controlled for caloric expenditure to determine whether vigorous exercise lowers blood pressure more than moderate intensity exercise.

Given that time is a precious resource in today’s busy world, most individuals have limited time for exercise. Knowing how to make every minute you can devote to aerobic exercise count is valuable. Clearly, vigorous exercise results in more improvements in aerobic capacity and greater reductions in heart disease and premature death than moderate intensity exercise. With regard to risk factors like cholesterol and triglycerides, moderate intensity exercise seems to be as effective as vigorous intensity. However, there are many factors to consider when determining your optimal exercise intensity including age, current fitness level, health status, risk factors for cardiovascular disease, and exercise preferences. Your physician and an experienced fitness professional can help you select the best intensity to improve health and best meet your overall fitness goals.  

So what is the take home message? For everyone, reduce the amount of time spent each day in sedentary activities and break up the periods of inactivity throughout the day. Use activities like standing, walking, stair climbing or even seated stretching or strengthening exercises to incorporate more activity into your day. What if you can’t seem to work the recommended 150 minutes of moderate intensity exercise into your schedule right now? Research suggests that less than 150 minutes of moderate intensity aerobic activity per week that may not include all components of fitness (aerobic, strengthening and flexibility) is likely to provide some health benefits, especially in sedentary individuals. For those just starting an exercise program, begin with moderate intensity exercise with the goal of exercising consistently. The most important take home message is GET MOVING! 

1American College of Sports Medicine. (2011). Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise. Medicine and Science in Sports and Exercise. 43(7), 1334-1359. 2DiPietro, L., Dziura, J., Yeckel, C.W. and Neufer, P.D. (2006). Exercise and improved insulin sensitivity in older women: evidence of the enduring benefits of higher intensity training. Journal of Applied Physiology. 100(1):142-149.