Abstract

Effects of High Intensity Interval Training on Plasma Levels of GH and IGF-I

Introduction: It is well-recognized that exercise has a significant impact on the GH/IGF system but less is known about the effects of HIIT on this axis. Aim of the present study was to evaluate the effect of ten weeks of HIIT on plasma levels of GH and IGF-I in healthy men. Methods: Twenty young men (age 23.34 ± 2.56 weight 72.47 ± 12.01 height 174.10 ± 5.75) recruited and randomly assigned into control (n=10) and HIIT (n=12) groups. HIIT protocol was started with 4 cycles. Then, every two weeks one cycle was added to the previous ones. Finally, it was to 8 cycles/ session in tenth weeks that lasted 16 minutes. Blood samples were collected prior to and after HIIT program for all subjects and IGF-I and GH levels were measured. Result: HIIT subjects showed a signi�?¯�?¬�?cant increase in IGF-I (P=0.002, F=12.38). However, no significant change was shown in GH levels (P=0.716, F=0.62). Discussion and conclusion: Our �?¯�?¬�?ndings indicate that the HIIT caused increase in circulating levels of IGF-I independently from GH levels. Both hormones may contribute to positive effects of anabolic conditions.

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