Update on the effects of physical activity on insulin sensitivity in humans.
Level 5 - mechanism / opinion, no new human data
Narrative review of human studies and physiological mechanisms without systematic search methodology
PubMed 28879026 · doi:10.1136/bmjsem-2016-000143
What was done
The authors conducted a narrative review summarizing literature and recent (2013–2016) findings on the effects of physical activity, exercise intensity, and exercise modalities (aerobic, resistance, and high-intensity interval training) on whole-body insulin sensitivity, glycaemic regulation, and skeletal muscle signaling in humans.
What was found
The abstract reports no numerical values, effect sizes, or confidence intervals. It qualitatively reports that regular physical activity improves insulin sensitivity and reduces the risk of insulin resistance, metabolic syndrome, and type 2 diabetes. Higher energy expenditures and intensities frequently show greater benefits. Aerobic exercise improves insulin sensitivity even without improvements in maximal oxygen consumption, and combining aerobic and resistance modalities may outperform single modes. Key biological mechanisms highlighted include AMPK- and Akt-mediated GLUT4 translocation, reduced intramuscular saturated fatty acids and ceramides, and increased capillarisation.
Why it matters
This review integrates evidence across exercise modalities and physiological mechanisms, reinforcing exercise as a direct therapeutic tool for glycaemic control regardless of major cardiorespiratory fitness gains.
Limits
As a narrative review, it lacks a systematic methodology, study quality appraisal, and meta-analytic synthesis. The abstract reports no participant counts or effect magnitudes, and notes ongoing debate regarding the extent to which benefits depend on concomitant fat loss.
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