Other research by the same authors revealed that interval-walking training or IWT where the intensity of the training alternates more favorably improves glycaemic control in people with type 2 diabetes when compared to continuous-walking training or CWT matched to have the same overall energy expenditure.
For the new study - conducted by Dr. Thomas Solomon and colleagues at the University of Copenhagen in Denmark, and published in Diabetologia, the journal of the European Association for the Study of Diabetes - the authors analyzed the potential mechanisms behind the effect. Individuals with type 2 diabetes were randomized into three groups:
- A control group (CON)
- An IWT group
- An energy-expenditure-matched CWT group
Training groups were prescribed highly standardized but free-living and unsupervised training for five, 60-minute sessions per week. A hyperglycaemic clamp was used to measure insulin secretion a standard method whereby glucose is infused at a constant rate and then used to work out how much insulin is being produced. Glucose isotope tracers were infused to measure glucose metabolism and skeletal muscle biopsies were taken to assess insulin signaling. These variables were measured before and after a four-month intervention.
The researchers found that:
- Improved blood sugar control was only evident in the IWT group. This was likely to be caused by IWT-induced increases in insulin sensitivity and increased peripheral glucose disposal, which is indicative of improved glucose metabolism.
- No changes occurred in the CWT or CON groups and only IWT improved insulin signaling in skeletal muscle.
- The most important finding of this study is that IWT, but not CWT, increased insulin sensitivity without a compensatory decrease in insulin secretion, thus improving the overall impact of insulin on blood sugar in these patients.
- Whether these beneficial effects of IWT continue and result in better health outcomes in the long term must be determined in order to justify the clinical utility of interval training for people with type 2 diabetes.