Extremely short duration high intensity interval training substantially improves insulin action in young healthy males

John A Babraj,James A Timmons,Greg Cottrell,Fergus M Guppy,Niels Bj Vollaard,Cameron Keast

doi:10.1186/1472-6823-9-3

Abstract

BackgroundTraditional high volume aerobic exercise training reduces cardiovascular and metabolic disease risk but involves a substantial time commitment. Extremely low volume high-intensity interval training (HIT) has recently been demonstrated to produce improvements to aerobic function, but it is unknown whether HIT has the capacity to improve insulin action and hence glycemic control.MethodsSixteen young men (age: 21 ± 2 y; BMI: 23.7 ± 3.1 kg·m-2; VO2peak: 48 ± 9 ml·kg-1·min-1) performed 2 weeks of supervised HIT comprising of a total of 15 min of exercise (6 sessions; 4–6 × 30-s cycle sprints per session). Aerobic performance (250-kJ self-paced cycling time trial), and glucose, insulin and NEFA responses to a 75-g oral glucose load (oral glucose tolerance test; OGTT) were determined before and after training.ResultsFollowing 2 weeks of HIT, the area under the plasma glucose, insulin and NEFA concentration-time curves were all reduced (12%, 37%, 26% respectively, all P < 0.001). Fasting plasma insulin and glucose concentrations remained unchanged, but there was a tendency for reduced fasting plasma NEFA concentrations post-training (pre: 350 ± 36 v post: 290 ± 39 μmol·l-1, P = 0.058). Insulin sensitivity, as measured by the Cederholm index, was improved by 23% (P < 0.01), while aerobic cycling performance improved by ~6% (P < 0.01).ConclusionThe efficacy of a high intensity exercise protocol, involving only ~250 kcal of work each week, to substantially improve insulin action in young sedentary subjects is remarkable. This novel time-efficient training paradigm can be used as a strategy to reduce metabolic risk factors in young and middle aged sedentary populations who otherwise would not adhere to time consuming traditional aerobic exercise regimes.

Highlights

Traditional high volume aerobic exercise training reduces cardiovascular and metabolic disease risk but involves a substantial time commitment
Glucose responses Fasting plasma glucose concentrations were unaltered after 2 weeks of highintensity interval training (HIT)
In the present study we demonstrate for the first time that only a few minutes of high intensity interval exercise performed over two weeks is required to substantially improve both insulin action and glucose homeostasis in sedentary young males

Summary

Introduction

Traditional high volume aerobic exercise training reduces cardiovascular and metabolic disease risk but involves a substantial time commitment. The estimated direct and indirect economic costs of cardiovascular disease (CVD) in the US for 2008 are estimated at $287 billion [2]. The risk of developing CVD and T2D can be modified by regular physical activity [3]. As we do not understand the precise mechanisms which link physical activity and a reduced risk of developing CVD or T2D, the scientific rationale for current health guides needs to be improved [4]. For exercise guidelines to yield a positive economic benefit for society, as well as a health benefit for the individual, should the regime reliably modify key disease risk factors, it must be plausible to implement

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