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Logo of bmcendiBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Endocrine Disorders
 
BMC Endocr Disord. 2009; 9: 3.
Published online Jan 28, 2009. doi:  10.1186/1472-6823-9-3
PMCID: PMC2640399
Extremely short duration high intensity interval training substantially improves insulin action in young healthy males
John A Babraj,#1 Niels BJ Vollaard,#1 Cameron Keast,1 Fergus M Guppy,1 Greg Cottrell,1 and James A Timmonscorresponding author1,2
1Translational Biomedicine, School of Engineering and Physical Sciences, Heriot-Watt University Edinburgh, Scotland, UK
2The Wenner-Gren Institute, Arrhenius Laboratories, Stockholm University, Sweden
corresponding authorCorresponding author.
#Contributed equally.
John A Babraj: j.babraj/at/hw.ac.uk; Niels BJ Vollaard: n.vollaard/at/hw.ac.uk; Cameron Keast: ck51/at/hw.ac.uk; Fergus M Guppy: fmg1/at/hw.ac.uk; Greg Cottrell: gc29/at/hw.ac.uk; James A Timmons: jamie.timmons/at/gmail.com
Received September 10, 2008; Accepted January 28, 2009.
Abstract
Background
Traditional 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.
Methods
Sixteen 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.
Results
Following 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).
Conclusion
The 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.
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