Mechanisms behind the superior effects of interval vs continuous training on glycaemic control in individuals with type 2 diabetes: a randomised controlled trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 25099941 · doi:10.1007/s00125-014-3334-5
What was done
Thirty-two individuals with type 2 diabetes not on exogenous insulin were randomly allocated to a control group (n = 8), an interval walking training group (IWT, n = 12), or an energy expenditure-matched continuous walking training group (CWT, n = 12). Exercise groups were prescribed free-living training five sessions per week (60 min/session) for 4 months. Outcomes were evaluated before and after the intervention using a three-stage hyperglycaemic clamp with glucose isotope tracers and skeletal muscle biopsies in an unblinded hospital setting.
What was found
Improvements in glycaemic control were observed only in the IWT group, with increases in insulin sensitivity index (49.8 ± 14.6%; p < 0.001), peripheral glucose disposal (14.5 ± 4.9%; p < 0.05), and disposition index (66.2 ± 21.8%; p < 0.001), while no changes occurred in the CWT or control groups. Only IWT improved skeletal muscle insulin signalling via increased insulin-stimulated AS160 phosphorylation (29.0 ± 10.8%; p < 0.05). No changes occurred in insulin secretion during hyperglycaemia alone, hyperglycaemia plus glucagon-like peptide 1 infusion, or arginine injection.
Why it matters
This study indicates that alternating exercise intensity, rather than volume or mean energy expenditure alone, is a key driver of improvements in insulin sensitivity and peripheral glucose disposal in type 2 diabetes.
Limits
The study had a small sample size (n = 32 across three groups) and lacked blinding. Training was carried out in free-living conditions, and the sample was limited to individuals with type 2 diabetes not on exogenous insulin.
Cited by
- supports Interval walking alternating between 75% and 60% intensity produces greater improvements in 24-hour glucose regulation, waist circumference, BMI, and HbA1c than continuous walking at 65% intensity.