Abstract
Introduction
Growing evidence indicates that circulating concentrations of insulin-like growth factor 1 (IGF-I), along with IGF-I relative to IGF-binding proteins (IGFBP), are associated with an increased risk of cancer. In accord, regular exercise is linked with a lower risk of cancer.
Purpose
To assess the effects of a 16-week home-based strength training (HBST) program on serum IGF-I, IGFBP-1 and IGFBP-3.
Methods
A total of 32 obese Latino adolescent males (aged 14–18 years) were randomized into a twice-weekly HBST (n = 16) or a control group (C, n = 16) for 16 weeks. The following were measured at pre- and post-intervention: IGF-I, IGFBP-1 and IGFBP-3, glucose/insulin indices by oral and/or intravenous (IV) glucose tolerance tests, strength by one-repetition maximum (1RM), dietary intake by 3-d records, body composition by DEXA and physical activity using the Actigraph GT1X. The generalized linear model (GLM) was used to assess differences in changes among outcome measures between the HBST and C groups.
Results
Exercise adherence in the HBST group was 89%. IGF-1 showed a trend for significant within-subject improvements (p = 0.078) but no significant within-subject or between-subject differences for IGFBP-1, IGFBP-3 two-glucose, fasting glucose or 2-h glucose (p > 0.05). There was a significant decrease (p > 0.05) in fasting glucose in the C group (p = 0.02) and also in the intervention group (p = 0.03) between baseline and follow-up testing. A significant difference was also found in the C group for 2-h glucose with an increase at follow-up testing (p = 0.04).
Conclusions
Though not statistically significant (p < 0.05), the results indicated that a 16-week HBST program decreased IGF-I and increased IGFBP-1, along with IGFBP-3, concentrations among overweight/obese Latino boys. However, further studies should consider increasing either the dose or the duration of the intervention to elicit greater improvements in this at-risk pediatric population.
A home-based, transtheoretical change model designed strength training intervention to increase exercise to prevent osteoporosis in Iranian women aged 40-65 years: a randomized controlled trial
