Update on the effects of physical activity on insulin sensitivity in humans

Abstract

Purpose and methodsThis review presents established knowledge on the effects of physical activity (PA) on whole-body insulin sensitivity (SI) and summarises the findings of recent (2013–2016) studies.Discussion and conclusionsRecent studies provide further evidence to support the notion that regular PA reduces the risk of insulin resistance, metabolic syndrome and type 2 diabetes, and SI improves when individuals comply with exercise and/or PA guidelines. Many studies indicate a dose response, with higher energy expenditures and higher exercise intensities, including high intensity interval training (HIIT), producing greater benefits on whole-body SI, although these findings are not unanimous. Aerobic exercise interventions can improve SI without an associated increase in cardiorespiratory fitness as measured by maximal or peak oxygen consumption. Both aerobic and resistance exercise can induce improvements in glycaemic regulation, with some suggestions that exercise regimens including both may be more efficacious than either exercise mode alone. Some studies report exercise-induced benefits to SI that are independent of habitual diet and weight loss, while others indicate an association with fat reduction, hence the debate over the relative importance of PA and weight loss continues. During exercise, muscle contraction stimulated improvements in SI are associated with increases in AMPK activity, which deactivates TCB1D1, promoting GLUT4 translocation to the cell membrane and thereby increasing glucose uptake. Postexercise, increases in Akt deactivate TCB1D4 and thereby increase GLUT4 translocation to the cell membrane. The reduction in intramuscular saturated fatty acids and concomitant reductions in ceramides, but not diacylglycerols, provide a potential link between intramuscular lipid content and SI. Increased skeletal muscle capillarisation provides another independent adaptation through which SI is improved, as does enhanced β cell activity. Recent studies are combining exercise interventions with dietary and feeding manipulations to investigate the potential for augmenting the exercise-induced improvements in SI and glycaemic control.

Objectively measured physical activity and cognitive function in urban‐dwelling older adults

“…The mechanisms underlying the association between physical inactivity and cognitive impairment remain to be elucidated. Insulin resistance (IR) is closely associated with inactivity and obesity, and PA improves IR . IR is also associated with cognitive impairment at least partly because insulin‐like signaling in the brain is crucial to promote neuronal survival and longevity …”

“…Insulin resistance (IR) is closely associated with inactivity and obesity, and PA improves IR. 10 IR is also associated with cognitive impairment 11 at least partly because insulin-like signaling in the brain is crucial to promote neuronal survival and longevity. 12 The association between cognitive impairment and inactivity might occur through the mechanism of IR, but this has not yet been clarified.…”

Claimed effects, outcome variables and methods of measurement for health claims proposed under European Community Regulation 1924/2006 in the area of blood glucose and insulin concentrations

“…Several factors related to lifestyle, including regular physical exercise and diet/weight loss, are known to positively affect IS [51,52]. TLC, which improve IS (i.e.…”

Soy husk extract improves physical and biochemical parameters of obese–diabetic rats through the regulation of PPARγ expression

“…A study conducted by Mason et al () showed that weight loss improved the insulin resistance of inactive and overweight/obese postmenopausal women. Weight loss, either by dietary control or performing physical activities, may facilitate better insulin response in obese individuals (Bird & Hawley, ). In line with the aforementioned findings, it can be postulated that it is an ideal approach to improve insulin sensitivity in obese individuals.…”