High Intensity Interval Training in Healthy Males Does not Improve Markers of Insulin

Purpose: Determine if three weeks of HIT (high-intensity interval training) improves fasting insulin sensitivity in healthy males. Methods: Participants were recreationally active ( ≥ 10 hours per week) men between 18 and 35 years of age (Ht: 180 ± 1.44 cm; Wt: 85 ± 2.95 kg; BMI: 26.1 ± 0.59 kg/m2; body fat: 19.7 ± 1.76%). HIT training occurred 3 days weekly for 3 weeks, at intensities equivalent to 7.5% of body mass. Training volume increased weekly as follows: three sprints per session (week 1), four sprints per session (week 2), and five sprints per session (week 3). Fasting blood samples were collected at baseline and after each week and tested for glucose and insulin. A repeated measures ANOVA was used to measure changes in both fasting glucose and insulin concentrations as well as HOMA(IR) (homeostatic model assessment) and QUICKI (quantitative insulin sensitivity check index). Results: Values were in the normal range throughout the study and there were no significant improvements in glucose (P = 0.346), insulin (P = 0.680), HOMA (P = 0.567), or QUICKI (P = 0.186), as a result of HIT. Conclusion: While HIT may be useful in maintaining insulin sensitivity in healthy males, 3-weeks of HIT did not further improve insulin sensitivity in this group.