Asked & Answered: How much exercise is too much?

January 20, 2020



By: Tim Gribbin, MEd, ATC*

HPRC staff get many Ask the Expert questions from Military Service Members, and the answers often include important information that can help you stay mission-ready, so you can perform well.

Asked & Answered
Last week I performed 780 minutes of moderate- to high-intensity exercise based on age-calculated, heart-rate percentages—and read that it might be TOO much. This week I’m on target to burn a combined total of 11,700 kCal in exercise alone, which might be a bit much as well. What are your thoughts?

The U.S. Department of Health and Human Services 2018 Physical Activity Guidelines for Americans recommend 150 minutes a week of moderate-intensity or 75 minutes a week of vigorous-intensity aerobic exercise such as running. Or for “additional and more extensive health benefits,” the recommendation is 300 minutes a week of moderate-intensity or 150 minutes a week of vigorous-intensity aerobic physical activity. While 780 minutes of activity a week is well over the recommendations, it’s hard to say if this is too much without knowing your specific activity habits and exercise goals.

With regard to your estimated calorie burn during the week, again, it’s hard to say if this is too much without knowing your specific dietary habits. To maintain your weight and muscle mass, you should be eating the same number of calories per day as you’re expending through exercise and your resting metabolic rate (the number of calories you use as you go about your daily life). When calculating calorie expenditure, keep in mind that energy expenditure (calories burned) measured by devices like smart watches are relatively inaccurate and should only be used as an estimation. If you find yourself unexpectedly gaining weight as you eat to match your calories burned, you might be overestimating how much you’re burning.

Something to consider when scheduling workouts is that 780 minutes per week of exercise equates to 13 hours, which is a huge burden on your time. Consider consulting with a personal trainer, or Army Master Fitness Trainer if your unit has one, to help develop a well-structured exercise plan that could help make your workouts more efficient and possibly cut down on the amount of time spent working out. For members in the other services, your unit might have a USMC Force Fitness Instructor or USAF Physical Training Leader who can work with you. In addition, consider meeting with a registered dietitian to take a look at your dietary habits and make sure you’re consuming enough calories and the proper nutrients to maintain your weight and muscle mass.

Ask the expert
To learn more about exercise or ask an HPRC expert about other issues that affect performance, visit the HPRC website.

About the Author
Tim Gribbin, of the Henry M. Jackson Foundation, is a Senior Scientist for the Consortium for Health and Military Performance (CHAMP) at the Uniformed Services University of the Health Sciences (USUHS).

Disclosure: The opinions and assertions expressed herein are those of the author and do not necessarily reflect the official policy or position of USUHS or DoD.The contents of this publication are the sole responsibility of the author and do not necessarily reflect the views, opinions, or policies of The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Government. The author has no financial interests or relationships to disclose.

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