Exercise Timing in Patients with Diabetes: Maximizing Metabolic Benefit

The promise of personalized medicine has led growing interest among researchers in innovative ways to maximize treatment effectiveness. Researchers at the University of Missouri and the National Research Council in Padova, Italy, recently investigated the role that timing of resistance exercise plays in lowering cardiovascular risk. They wondered if the time of day when diabetics exercise could explain the lower-than-expected exercise-derived benefits seen in some diabetics.

Previous studies have examined the benefit of aerobic exercise, but the researchers observed that aerobic exercise (especially after a meal) is impractical for many obese diabetics. Resistance exercise, consisting of short work periods with longer breaks, was suggested as a more practical alternative.

Abnormal post-prandial glucose or triacylglycerol (TAG) elevations have been shown to be a significant cardiovascular risk factor in type 2 diabetes. These researchers designed a small trial (N=13) and evaluated post-prandial glucose and TAG levels when diabetics performed resistance exercise before a meal, after a meal, or not at all.

Participants were obese, physician-diagnosed type 2 diabetics who did not use insulin but continued their current medication regimens. The researchers noted gastric emptying, endocrine responses, free fatty acids, and beta-cell function (via mathematical modeling).

Study participants completed a three-day program of controlled diet and exercise routines. The resistance exercises included leg presses, seated calf raises, seated chest flyes, seated back flyes, back extensions, shoulder raises, leg curls, and abdominal crunches. The researchers recorded clinical outcomes during each phase and then conducted statistical analyses to demonstrate the significance of their findings.

The study concluded that resistance exercise engenders a beneficial reduction in post-prandial glucose levels. Exercise after a meal was shown to produce a more effective reduction than exercise before a meal, however. Additionally, the authors noted that, for the first time, TAG levels were shown to be unaffected by resistance exercise before a meal.

The researchers suggested that resistance exercise is most effectively timed after a meal, although they acknowledged the benefits were modest. They suggested, unsurprisingly, that appropriate exercise of any sort, regardless of timing, offers important metabolic benefits for type 2 diabetics. This study appears ahead of print in the Journal of Applied Physiology.