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  • Sheri Colberg, PhD

Is It Better for Physical Activity to Be Continuous or Discontinuous?


Back when I started in exercise physiology, it was generally accepted that doing any aerobic activity continuously would give you greater fitness and health benefits. We compared moderate-intensity aerobic exercise (like walking, jogging, cycling, or swimming) with doing the same activity in shorter (but not necessarily harder) sessions or discontinuously. Until recently, the recommendation has been that people should exercise for at least 10 minutes at a time, and only people with a really limited capacity to be active were recommended to do shorter or discontinuous workout sessions.


Times have changed as we have learned more about different types and intensities of aerobic and other forms of training that can be beneficial, especially when it comes to management of blood glucose levels and overall health (1, 2). For instance, doing high-intensity interval training (HIIT) for half as much total time as a moderate-intensity continuous activity increases aerobic fitness at least as much, if not more, than the continuous one and has a similar impact on fasting insulin levels in adults with type 2 diabetes (3). Of course, not everyone can or wants to do harder intervals, but even doing the same total amount of the same intensity differently—such as doing three separate 10-minute sessions instead of one continuous 30-minute session—has the same impact on blood glucose levels in adults with prediabetes or diabetes (4).


Are there other equally beneficial ways to be active? Recently, a systematic review and meta-analysis with 27 studies (and a total of 635 adult participants) with and without diabetes looked at the impact of doing a single session of continuous aerobic activity versus accumulating the same amount of activity in much shorter bouts over the course of the day (5). Interestingly, they found that doing physical activity “breaks” that were mostly low- or moderate-intensity was more effective than doing a single continuous activity when it came to managing blood glucose after meals, even with no change in post-meal insulin levels. That means it may be possible to manage blood glucose simply by being more active all day long, even in short sessions, which gives people more options for becoming and staying more physically active to benefit their health and diabetes management when they have limited time or a lower capacity to exercise.


We have even learned in the past decade that not sitting for long periods of time can improve how metabolism works. Plenty of studies have now reported on the benefits of breaking up sedentary time with any type of physical movement (even standing), whether you have diabetes or not (6-8). Taking just a short (10-minute) walk after a meal can keep blood glucose levels from rising as much (9) and so can doing 3 minutes of activity every 20 minutes after a meal, and people with higher levels of insulin resistance to start with benefit the most (10).


The 2018 U.S. federal recommendations on physical activity (11) now reflect much of this new knowledge (available online at https://health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf). They state that “Adults should move more and sit less throughout the day. Some physical activity is better than none. Adults who sit less and do any amount of moderate-to-vigorous physical activity gain some health benefits.” Of course, the more you do, the more benefits you gain—at least up to a point—and adults can benefit from doing a variety of activities weekly that work on cardiorespiratory fitness, strengthen muscles and joints, increase flexibility, and improve balance and agility. Nonetheless, it may be time to implement a nationwide requirement that everyone get up and start moving after every meal. Just think how much that would improve our collective health!

References:

1. Wu N, Bredin SSD, Guan Y, Dickinson K, Kim DD, Chua Z, et al. Cardiovascular Health Benefits of Exercise Training in Persons Living with Type 1 Diabetes: A Systematic Review and Meta-Analysis. J Clin Med. 2019;8(2).

2. Pan B, Ge L, Xun YQ, Chen YJ, Gao CY, Han X, et al. Exercise training modalities in patients with type 2 diabetes mellitus: a systematic review and network meta-analysis. Int J Behav Nutr Phys Act. 2018;15(1):72.

3. Li J, Cheng W, Ma H. A Comparative Study of Health Efficacy Indicators in Subjects with T2DM Applying Power Cycling to 12 Weeks of Low-Volume High-Intensity Interval Training and Moderate-Intensity Continuous Training. J Diabetes Res. 2022;2022:9273830.

4. Chang CR, Russell BM, Dempsey PC, Christie HE, Campbell MD, Francois ME. Accumulating Physical Activity in Short or Brief Bouts for Glycemic Control in Adults With Prediabetes and Diabetes. Can J Diabetes. 2020;44(8):759-67.

5. Zhang X, Zheng C, Ho RST, Miyashita M, Wong SHS. The Effects of Accumulated Versus Continuous Exercise on Postprandial Glycemia, Insulin, and Triglycerides in Adults with or Without Diabetes: A Systematic Review and Meta-Analysis. Sports Med Open. 2022;8.

6. Gillen JB, Estafanos S, Williamson E, Hodson N, Malowany JM, Kumbhare D, et al. Interrupting prolonged sitting with repeated chair stands or short walks reduces postprandial insulinemia in healthy adults. J Appl Physiol (1985). 2021;130(1):104-13.

7. Bailey DP, Maylor BD, Orton CJ, Zakrzewski-Fruer JK. Effects of breaking up prolonged sitting following low and high glycaemic index breakfast consumption on glucose and insulin concentrations. Eur J Appl Physiol. 2017;117(7):1299-307.

8. Dempsey PC, Owen N, Yates TE, Kingwell BA, Dunstan DW. Sitting Less and Moving More: Improved Glycaemic Control for Type 2 Diabetes Prevention and Management. Curr Diab Rep. 2016;16(11):114.

9. Bellini A, Nicolò A, Bazzucchi I, Sacchetti M. Effects of Different Exercise Strategies to Improve Postprandial Glycemia in Healthy Individuals. Med Sci Sports Exerc. 2021;53(7):1334-1344.

10. Dempsey PC, Larsen RN, Winkler EAH, Owen N, Kingwell BA, Dunstan DW. Prolonged uninterrupted sitting elevates postprandial hyperglycaemia proportional to degree of insulin resistance. Diabetes Obes Metab. 2018;20(6):1526-30.

11. Piercy KL, Troiano RP, Ballard RM, Carlson SA, Fulton JE, Galuska DA, et al. The Physical Activity Guidelines for Americans. JAMA. 2018;320(19):2020-8.

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