Combo Training Superior for Insulin Sensitivity

Combo Training Superior for Insulin Sensitivity

by: Robbie Durand

Insulin does a lot of important things in the body. Most importantly, insulin transports glucose from the blood into our cells to be burned for energy or stored as glycogen. It also promotes muscle protein synthesis and helps augment muscular hypertrophy, especially following resistance training. When gluocose levels become to high, it can cause major health effects such as hyperglycemic toxicity (i.e. excess levels of glucose in the body) to neurons, pancreatic cells, the arterial walls and the generation of excessive levels of reactive oxygen species. Insulin is vital for health but insulin levels can increase with obesity and lead to heart disease and other vascular issues. Insulin sensitivity refers to how sensitive the body is to the effects of insulin. Exercise has been shown to increase insulin sensitivity, which is a big health benefit.

Athletes who are insulin sensitive will have cells that are far more permeable to insulin than those who are resistant, resulting in the muscle cells absorbing the glucose which the insulin is transporting from the blood. If the cell is resistant then the glucose will be converted and stored as visceral fat rather than in the muscle. The body is most sensitive to insulin first thing in the morning and immediately post training. By increasing ones sensitivity to insulin and improving cellular permeability, carbohydrates consumed post training will more than likely replenish and repair the muscle rather than being stored as visceral fat, thus resulting in hypertrophy of the muscle and an increase in lean muscle mass. Most health organizations recommend a combination of aerobic training and resistance training, yet few studies have compared their acute and sustained effects alone and in combination on health parameters.According to the newest research in the prestigious Journal of Applied Physiology, the combination of aerobic and resistance exercise results in the greatest impact on insulin sensitivity.

Researchers compared the effects of aerobic training, resistance training and the combination of aerobic and resistance exercise on insulin action at both acute (within 24 hours of the last exercise bout) and sustained (14 days of detraining) phases. Subjects completed the intervention and were assigned to:

1.) the resistance training protocol was 3 days/week, 8 exercises, 3 sets/exercise, 8-12 repetitions/set

2) aerobic training: equivalent to ~19.2 km/wk (12 miles/wk) at 75% peak VO₂

3) aerobic training/resistance training : the combination of aerobic training and resistance training.

Eighty-eight subjects completed all pre- and post-intervention testing visits. Insulin sensitivity, glucose effectiveness and disposition index were measured via a frequently sampled, intravenous glucose tolerance test. At the end of the study, the combination aerobic training/resistance training group resulted in significantly greater improvements in insulin sensitivity than either aerobic training or resistance training alone. Approximately 52% of the improvement in insulin sensitivity by aerobic training/resistance training was retained 14 days after the last exercise training bout. In summary, only aerobic training/resistance training (which required twice as much time as either alone) led to significant acute and sustained benefits in insulin sensitivity. So the research seems to suggest that combo training is best for improving insulin sensitivity.

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