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Hyperglycemia reduces benefits of aerobic exercise

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MedicalXpress has an article on the deleterious effect of hyperglycemia.  Increased blood sugar levels may decrease benefits of aerobic exercise 

Very short summary – avoiding hyperglycemia starts a virtuous circle where you (or at least mice as in the experiment) get more benefits from exercise which helps you maintain normal blood sugar levels.

Highlights from the article:

some benefits of aerobic exercise may be dampened by higher-than-normal blood sugar levels, a condition known as hyperglycemia.

These diminished gains are seen in mouse models and humans with chronic hyperglycemia that is in the "prediabetes" range … The study also showed that this maladaptive trait is independent of obesity and insulin levels in the blood.

Clinical studies have demonstrated that people with diabetes or chronically high levels of blood sugar struggle to improve their aerobic exercise capacity compared to people with normal blood sugar levels. 

Her team used two mouse models that reflect the two major causes of hyperglycemia in humans. One group of mice consumed a Western diet, high in sugar and saturated fat, which caused some weight gain in addition to hyperglycemia. The other group was modified to produce less insulin, which caused similar increases in blood sugar as the Western diet, even though the mice ate a diet lower in sugar and fat, and maintained normal body weight. 

 both hyperglycemic groups, animals ran around 500 kilometers over the course of the study but, on average, failed to improve their aerobic exercise capacity compared to mice with lower blood sugar levels

Looking in more detail at skeletal muscle in these mice, she and her colleagues saw that the muscle was not adapting to the aerobic challenge as muscle normally would.

The scientists propose that high levels of blood sugar may prevent muscle remodeling in part by modifying the "extracellular matrix" proteins in the space between the muscle cells, where blood vessels are formed.

Following up on these animal findings in clinical tests with young adult volunteers, the Joslin scientists found that those who had higher blood sugar levels in response to ingesting glucose, a condition known as impaired glucose tolerance, showed the lowest aerobic exercise capacity. "Looking at how their muscles responded to a single bout of typical aerobic exercise, we also saw that those with the lowest glucose tolerance had the highest activation of the JNK signaling pathway, which blocks aerobic adaptations," she says.

the study suggests several approaches that might help people with chronic hyperglycemia eventually overcome the obstacles to building aerobic capacity. One is to adopt a diet designed to keep blood sugar levels low. Another is to take existing diabetes drugs designed to keep blood sugar levels in normal ranges.

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  • 4 weeks later...

As noted in the first post , in this case “inducing hyperglycaemia in the weeks before exercise training is associated with blunted gains in exercise capacity and aerobic remodelling, suggesting that hyperglycaemia may impart a resistance to aerobic training adaptations.“  

As per Tom’s recounted responses to exercise and perennial and recent discourse into “individualized responses,” ( and the post above), the authors speculated that this may account for these differences in at least some individuals.

OTOH, to Dean’s point in other threads, indeed there was still some improvement even with blunted aerobic capacity, and other benefits such as improved insulin sensitivity.

Ar least this mechanism is partially modifiable via CR; there are others no doubt not so much or not at all.... so like so many things a mixed picture. 

(1) MacDonald TL, Pattamaprapanont P, Pathak P, et al. Hyperglycaemia is associated with impaired muscle signalling and aerobic adaptation to exercise [published online ahead of print, 2020 Jul 20]. Nat Metab. 2020;10.1038/s42255-020-0240-7. doi:10.1038/s42255-020-0240-7

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Edited by Mechanism
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