Excessive exercise training causes mitochondrial functional impairment and decreases glucose tolerance in healthy volunteers.
Level 3 - non-randomized controlled study
Non-randomized prospective interventional cohort and cross-sectional comparison
PubMed 33740420 · doi:10.1016/j.cmet.2021.02.017
What was done
Healthy volunteers completed a 4-week exercise intervention with progressively increasing training loads. Researchers tracked changes in glucose tolerance, intrinsic mitochondrial function and dynamics, physical exercise capacity, and whole-body metabolism. Continuous blood glucose profiles were also measured in world-class endurance athletes and compared with a matched control group.
What was found
The abstract reports no numerical values, effect sizes, or statistical metrics. Following the week with the highest exercise load, participants experienced a reduction in intrinsic mitochondrial function that coincided with disturbances in glucose tolerance and insulin secretion. World-class endurance athletes showed impaired glucose control compared with matched controls.
Why it matters
The findings demonstrate a potential upper limit to exercise volume, showing that excessive overload can transiently impair mitochondrial respiration and glycemic regulation in healthy individuals.
Limits
The abstract does not disclose the sample size, participant demographics, specific exercise protocols, or numerical data. The interventional component lacks a randomized non-training comparator, and the elite athlete evaluation is an observational cross-sectional comparison.
Cited by
- supports Excessive volumes of high-intensity interval training (HIIT) can impair mitochondrial function.