How a Single Workout Helps Diabetes (September 26, 2022)
Lowering blood sugar levels with just one workout may sound too good to be true, but a single session of exercise is a powerful way to improve several areas of health in diabetes (1). As you may have suspected, there is a catch, however. To maintain these health improvements, exercise has to be done on a regular basis. Nonetheless, it is still motivating to know that you can experience immediate health benefits with just one workout, especially when it comes to muscle-strengthening exercise! This type of exercise typically includes weight machines, free weights (example: handheld weights), elastic/resistance bands, or bodyweight movements like sit-ups or push-ups. These benefits extend not only to your physical health, but to your mental health as well. This post is going to focus specifically on how a single session of muscle-strengthening exercise improves mental health in different groups of people, and physical health in people with type 2 diabetes. This information is summarized in the video below.
Anxiety. While most of the research related to exercise and mental health has focused on aerobic exercise, there is evidence that a single muscle-strengthening workout can help to reduce symptoms of anxiety (2). These benefits have been seen in people with fibromyalgia, breast cancer, general anxiety disorder, ischemic stroke, and in postmenopausal women, law officers, healthy older adults, and office workers. How muscle-strengthening exercise affects anxiety seems to be related to intensity, with low- to moderate-intensity exercise appearing to be the most effective in reducing anxiety symptoms. Muscle-strengthening exercise intensity is commonly expressed as a percentage of the maximum amount that someone can lift per exercise with correct technique, or one-repetition maximum (1 RM). Intensity can only be fully understood in the context of how difficult the resistance was to move combined with the number of repetitions completed. In studies that have found that a single muscle-strengthening workout reduces anxiety, researchers used very low-intensity (10% of 1 RM) for 3 minutes at a rate of 20 repetitions (reps) per minute (60 repetitions total) (3), low- to moderate-intensity (50-60% of 1 RM) for eight reps (4), and low-intensity (50-55% of 1 RM) for 10-11 reps (5). For someone new to muscle-strengthening exercise, starting at low- to moderate-intensities may reduce feelings of anxiety which could lead to more consistent exercise habits.
Glucose (sugar). The most important area of cardiometabolic (cardiovascular and metabolic) health for people with diabetes to consider is how exercise benefits their blood sugar levels. Our research team conducted a review that looked at how one muscle-strengthening workout improved metabolic (glucose and insulin) and cardiovascular (blood pressure and triglycerides) health in people with type 2 diabetes, and the results were very positive (1)! One muscle-strengthening workout can reduce blood glucose levels by ~14.5% for up to 24 hours (6). Exercise is a strong stimulus for clearing out extra glucose in the blood even in the absence of insulin, as the muscle will use the glucose for energy.
Insulin. Our review also found that a single muscle-strengthening workout can reduce insulin levels in the blood by 48% and keep these levels lowered by 21% for up to 18 hours (7). This decrease in blood insulin levels shows that the muscle is interacting with insulin in a helpful way (insulin sensitivity) to help clear extra glucose out of the blood and into the muscle. We do not currently know if these insulin lowering effects last longer than 18 hours because only one other study has tested it for a longer period of time. This other study found no effects of muscle-strengthening exercise on insulin levels for up to 24 hours, but they used a different technique to measure insulin and did not provide dietary guidelines to participants (6). Knowing how long the benefits of exercise last helps us in determining how frequently to exercise.
Cardiovascular disease risk: blood pressure and triglycerides. The last area of our review, cardiovascular disease risk, found that a session of muscle-strengthening exercise outperformed aerobic exercise by decreasing systolic blood pressure by ~7 mmHg and diastolic blood pressure by ~5 mmHg for up to 24 hours (8). The higher intensity of the muscle-strengthening workout probably caused the blood vessels to expand (dilate) more than the moderate-intensity aerobic exercise, and likely was the reason that blood pressure decreased more with this type of exercise. Also, another study found that a muscle-strengthening workout done 45 minutes after a meal lowered triglycerides in the blood by 92% (9)! Since exercise causes our bodies to use triglycerides stored in our muscle and other types of tissues (adipose) for energy, it is likely that the decrease in blood triglycerides was due to the body trying to replenish emptied stores.
A single session of muscle-strengthening exercise can lower anxiety, blood glucose, insulin, blood pressure, and triglycerides for many hours after the workout. Since these benefits only last for a certain amount of time, exercise must be done on a regular basis to maintain and further these improvements. It is clear that aerobic exercise is not the only story around town for improving metabolic and cardiovascular health in people with type 2 diabetes. Muscle-strengthening exercise has long been considered a primary way to improve bone and muscle health and general movements of everyday life. Now that we know how effective this type of exercise is in improving other areas of health, it’s time for the science to catch up with aerobic exercise.
Sources Used:
Brown EC, Franklin BA, Regensteiner JG, Stewart KJ. Effects of single bout resistance exercise on glucose levels, insulin action, and cardiovascular risk in type 2 diabetes: A narrative review. J Diabetes Complications. 2020 Aug;34(8):107610. doi: 10.1016/j.jdiacomp.2020.107610. Epub 2020 May 3. PMID: 32402840.
Strickland JC, Smith MA. The anxiolytic effects of resistance exercise. Front Psychol. 2014 Jul 10;5:753. doi: 10.3389/fpsyg.2014.00753. PMID: 25071694; PMCID: PMC4090891.
O'Connor PJ, Cook DB. Anxiolytic and blood pressure effects of acute static compared to dynamic exercise. Int J Sports Med. 1998 Apr;19(3):188-92. doi: 10.1055/s-2007-971902. PMID: 9630024.
Bartholomew JB, Linder DE. State anxiety following resistance exercise: the role of gender and exercise intensity. J Behav Med. 1998 Apr;21(2):205-19. doi: 10.1023/a:1018732025340. PMID: 9591170.
Bibeau WS, Moore JB, Mitchell NG, Vargas-Tonsing T, Bartholomew JB. Effects of acute resistance training of different intensities and rest periods on anxiety and affect. J Strength Cond Res. 2010 Aug;24(8):2184-91. doi: 10.1519/JSC.0b013e3181ae794b. PMID: 19834350.
Fenicchia LM, Kanaley JA, Azevedo JL Jr, Miller CS, Weinstock RS, Carhart RL, Ploutz-Snyder LL. Influence of resistance exercise training on glucose control in women with type 2 diabetes. Metabolism. 2004 Mar;53(3):284-9. doi: 10.1016/j.metabol.2003.10.007. PMID: 15015138.
Fluckey JD, Hickey MS, Brambrink JK, Hart KK, Alexander K, Craig BW. Effects of resistance exercise on glucose tolerance in normal and glucose-intolerant subjects. J Appl Physiol (1985). 1994 Sep;77(3):1087-92. doi: 10.1152/jappl.1994.77.3.1087. PMID: 7836108.
Morais PK, Campbell CS, Sales MM, Motta DF, Moreira SR, Cunha VN, Benford RE, Simões HG. Acute resistance exercise is more effective than aerobic exercise for 24h blood pressure control in type 2 diabetics. Diabetes Metab. 2011 Apr;37(2):112-7. doi: 10.1016/j.diabet.2010.08.008. Epub 2010 Dec 14. PMID: 21159536.
Heden TD, Winn NC, Mari A, et al. Postdinner resistance exercise improves postprandial risk factors more effectively than predinner resistance exercise in patients with
type 2 diabetes. J Appl Physiol (1985) 2015;118:624-34 https://doi.org/10.1152/japplphysiol.00917.2014.