Faculty Collaboration Database

Differential basal and exercise-induced IGF-I system responses to resistance vs. calisthenic-based military readiness training programs. Growth Horm IGF Res 2017 Feb;32:33-40

Date

12/17/2016

Pubmed ID

27979730

DOI

10.1016/j.ghir.2016.12.001

Scopus ID

2-s2.0-85008950444 (requires institutional sign-in at Scopus site)   13 Citations

Abstract

OBJECTIVE: The purpose of this study was to: 1) evaluate differential responses of the IGF-I system to either a calisthenic- or resistance exercise-based program and 2) determine if this chronic training altered the IGF-I system during an acute resistance exercise protocol.

DESIGN: Thirty-two volunteers were randomly assigned into a resistance exercise-based training (RT) group (n=15, 27±5y, 174±6cm, 81±12kg) or a calisthenic-based training group (CT) (n=17, 29±5y, 179±8cm, 85±10kg) and all underwent 8weeks of exercise training (1.5h/d, 5d/wk). Basal blood was sampled pre- (Week 0), mid- (Week 4) and post-training (Week 8) and assayed for IGF-I system analytes. An acute resistance exercise protocol (AREP) was conducted preand post-training consisting of 6 sets of 10 repetitions in the squat with two minutes of rest in between sets and the IGF-I system analytes measured. A repeated measures ANOVA (p≤0.05) was used for statistical analysis.

RESULTS: No interaction or within-subject effects were observed for basal total IGF-I, free IGF-I, or IGFBP-1. IGFBP-2 (pre; 578.6±295.7<mid; 828.6±104.2=post; 833.7±481.2ng/mL; p=0.008) and Acid Labile Subunit (ALS) changed over the exercise training (pre-; 16.2±1.3=mid-; 17.6±1.8>post-training; 14.3±1.9μg/mL; p=0.01). An interaction was observed for the RT group as IGFBP-3 increased from pre to mid (3462.4±216.4 vs. 3962.2±227.9ng/mL), but was not significant at the post-training time point (3770.3±228.7ng/mL). AREP caused all analytes except free IGF-I (40% decrease) to increase (17-27%; p=0.001) during exercise, returning to baseline concentration into recovery.

CONCLUSION: Post-training, bioavailable IGF-I recovered more rapidly post-exercise. 8wks of chronic physical training resulted in increased basal IGFBP-2 and IGFBP-3, decreased ALS, increased pre-AREP free IGF-I and a more rapid free IGF-I recovery post-AREP. While total IGF-I was insensitive to chronic physical training, changes were observed with circulating IGFBPs and bioavailable IGF-I. To glean the most robust information on the effects of exercise training, studies must move beyond relying solely on total IGF-I measures and should consider IGFBPs and bioavailable IGF-I as these components of the circulating IGF-I system are essential determinants of IGF-I physiological action.

Author List

Nindl BC, Alemany JA, Rarick KR, Eagle SR, Darnell ME, Allison KF, Harman EA

Author

Kevin Richard Rarick PhD Assistant Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Body Composition
Exercise
Humans
Insulin-Like Growth Factor Binding Protein 1
Insulin-Like Growth Factor Binding Protein 2
Insulin-Like Growth Factor Binding Protein 3
Insulin-Like Growth Factor I
Male
Military Personnel
Resistance Training