What is better for your health, exercise more at low intensity or exercise less with higher intensity? A number of studies have been performed to try to answer this question and one such study was published this month. For people who are trying to lose weight and stay fit, this information should help in the planning of fitness programs. Also, it is always important to discuss fitness programs with health care providers.
This trial was performed over 24 weeks in Ontario, Canada with 300 abdominally obese adults. The arms of the study were as follows:
- control group of 75 individuals (no exercise)
- low-intensity exercise group of 73 individuals (5 weekly sessions of exercise that consumed 180 or 300 calories per session for men or women, respectively, at 50% of maximum oxygen consumption) (average exercise time per session of 31 minutes)
- high-amount, low-intensity exercise group of 76 individuals (5 weekly sessions of exercise that consumed 360 or 600 calories per session for men or women, respectively, at 50% of maximum oxygen consumption) (average exercise time per session of 58 minutes)
- high-amount, high-intensity exercise group of 76 individuals (5 weekly sessions of exercise that consumed 360 or 600 calories per session for men or women, respectively, at 75% of maximum oxygen consumption) (average exercise time per session of 40 minutes)
The main outcomes that were measured were waist circumference and 2-hour glucose level.
Daily unsupervised physical activity and sedentary time was similar in all groups. The three different exercise groups reduced their waist circumferences by 3.9 to 4.6 cm by the end of the study. This was a significant difference from the control group, but there was not a significant difference amongst the three exercise groups. The results were similar for weight loss, which averaged about 16 pounds and 5-6% of body weight. In contrast, only the high-amount, high-intensity exercise group had a greater reduction in 2-hour glucose level than the control group. This reduced glucose level may indicate a reduced risk for diabetes, heart disease, and stroke.
Focusing on weight-loss goals only, 31 minutes 5 times a week (155 minutes per week) of low-intensity exercise achieved the same results as 290 minutes per week of low-intensity exercise or 200 minutes per week of high-intensity exercise. National guidelines call for 150 minutes per week of moderate-intensity exercise or 75 minutes per week of high-intensity exercise. Please note, however, that high-intensity exercise is probably defined differently between this study and national guidelines. As a rule of thumb, I normally think that low-intensity exercise will allow maintaining an unlabored conversation, moderate-intensity exercise will lead to a good sweat, while high-intensity exercise will take some concentration and determination to maintain.
Beyond simple weight loss, for more complete health, increased intensity of exercise (if determined safe and tolerable by a health care provider) is key. This does not have to be painful, dreaded workouts. Some simple ways to increase intensity include increasing the grade on a treadmill, increasing the amount of run vs walk during a run/walk session, increasing the resistance on an elliptical trainer or exercise bike, and tackling a hill rather than taking a flat route. For many people, adding some increased intensity, if done carefully, also adds some fun and variety to workouts.
Be healthy and be safe.
Published March 29, 2015
Ross R, Hudson R, Stotz PJ, et al. Effects of exercise amount and intensity on abdominal obesity and glucose tolerance in obese adults: a randomized trial. Ann Intern Med. 2015 Mar 3;162(5):325-334.