When managing blood sugar, exercise is often prescribed as a non-negotiable part of the routine. Most forms of movement, such as walking, yoga, and strength training, help the body regulate glucose better.
But while the benefits of regular exercise are well established, it is necessary to understand whether too much intensity might actually do more harm than good, especially for those with blood sugar issues.
Can going too hard at the gym interfere with your glucose control?
Certified diabetes educator and dietician Kanikka Malhotra tells indianexpress.com, “Very intense exercise (e.g., sprints, heavy resistance training) may result in stress-induced temporary hyperglycemia due to the release of stress hormones. Adrenaline and cortisol initiate glucose production by the liver through glycogenolysis and gluconeogenesis, circumventing the effects of insulin-modulated glucose uptake. This endocrine counterregulatory response occurs despite the overall result of exercise, as a reduction of the amount of glucose because the body perceives high-intensity exercise as a form of physiological stress.”
She adds that the post-exercise spike is “usually temporary (30 120 min after exercise) and can be long-lasting when one starts with a higher glucose concentration (>180 mg/dL).” Low to moderate-intensity non-exercise activity (such as brisk walking) does not have this effect because it uses muscular uptake of glucose more than stress hormones.
Risks for people with insulin resistance or diabetes when they engage in very intense forms of exercise, especially without proper recovery or fuel
The intense exercise is particularly dangerous to people with diabetes, admits Malhotra, adding, “Athletic effort in the presence of an elevated high start of glucose (>200 mg/dL) can accelerate hyperglycemia by catecholamine-stimulated hepatic glucose production. The danger of post-exercise hypoglycemia (4-24 h later) is caused by reduced glycogen stores in muscles/liver, especially when insulin/medications are not modified.”
She continues, “Engaging in physical activities with blood glucose levels of at least 250 mg/dL and the presence of detectable ketones can precipitate ketoacidosis among patients with type 1 diabetes. This is fortified by insufficient fueling (low pre-exercise carbohydrates) or recovery time.”
Also, the rapidity of uncontrolled diabetes causes increased strain on the cardiovascular system when the body is subjected to severe physical stress. “Hormonal reactions and metabolic weaknesses should be met with close glucose-related monitoring and activity adjustment to avert imminent complications,” stresses Malhotra.
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How to maintain a healthy balance
Malhotra says, “To keep blood sugar levels in check, moderate aerobic exercising, including cycling or swimming, is the perfect starter to keep glucose levels down and A1C levels improved. Add 2-3 sessions of high intensity (20 minutes or less) to complement, and be sure to wait at least 48 hours between any 2 of them. The red flags of the counterproductive nature of workouts are hyperglycemia (greater than 250 mg/dL) following exercise, hypoglycemia (less than 70 mg/dL), continued fatigue, increased thirst, presence of ketones or nighttime hypoglycemia following afternoon workouts.”
Before and after exercising, she adds, it is better to check the glucose levels to reduce the risk. When the pre-exercise glucose concentration is less than 100 mg/dL, use 15 g of carbohydrates. “It may also be beneficial to cut off basal insulin (by half) prior to the moderate exercise period. Do not use high-intensity interval training in the presence of ketones and trend using the continuous glucose monitors,” concludes Malhotra.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.