Serum levels of Insulin-like growth factor-1 (IGF-I) as an indicator associated with aerobic and anaerobic fitness assessment in adolescent boys

Insulin-like growth factor -1 (IGF-I) has a variety of roles, But the abundance of scientific evidence indicates that it is a metabolic biomarker associated with indicators of physical fitness and health. The present study examined the relationship between serum levels of IGF-I and aerobic fitness, anaerobic capacity and body fat percent, systolic, and diastolic blood pressure before and after the eight weeks of high intensity intermittent training (HIIT) in adolescent boys.

In this experimental study, 22 adolescent boys in a randomly and double-blinded design were allocated in two equal groups: HIIT group (N=11) and control group (N=11). Training programs were conducted 3-4 times per week for 8 weeks. The HIIT program consisted of 6-8 running sprints (30-60 seconds) with a 3.5-4 min recovery. Mentioned indicators assessments were performed 18-24 hours pre and post intervention.

IGF-1, Maximum Oxygen uptake (VO2max(, Peak Power Output (PPO) and mean power output (MPO) were significantly higher after 8 week HIIT than the pre-exercise training evaluations (P<0.001). Fatigue index and body fat percent decreased in HIIT trial after 8 week HIIT (P<0.001). Also, there was a significant positive correlation between IGF-I changes and aerobic fitness, anaerobic and body fat percentage. However, Systolic and diastolic blood pressure did not change significantly after the training period (P > 0.05).

The IGF-I can be used as an indicator to assess the fitness of adolescent boys.