The relationship between aerobic exercise capacity and circulating IGF-1 levels in healthy men and women

OBJECTIVES: To determine whether aerobic capacity is associated independent ly with insulin-like growth factor-I (IGF-1) levels in healthy community-dw elling men and women. SETTING: The Baltimore Longitudinal Study on Aging (BLSA). DESIGN: A cross-sectional analysis of data from the population-based cohort of the Baltimore Longitudinal Study of Aging (BLSA). PARTICIPANTS: We studied 181 men and 92 women aged 20 to 93 years, voluntee rs in the Baltimore Longitudinal Study on Aging (BLSA). Subjects were free of endocrine, renal, hepatic, gastrointestinal, or cardiac diseases, and th ey were taking no medications known to interfere with the growth hormone-IG F-l axis. MEASUREMENTS: All subjects underwent a single measurement of serum IGF-1 in the fasting state, as well as peak Oo, determinations during maximal tread mill exercise testing performed within one visit of the IGF-1 determination . Dual energy X-ray absorptiometry (DEXA) scans were performed in a subset of 171 subjects (64 women and 107 men) for determination of fat free mass ( FFM). RESULTS: In the pooled group of women and men, univariate regression analys is revealed that age was correlated strongly with decreasing IGF-1 levels ( r = -0.53, P < .001) and with peak (V) over dot o(2) (r = -0.56, P < .001). IGF-1 levels were also significantly correlated with peak (V) over dot o(2 ), (r = 0.29, P < .001). There were no significant gender-related differenc es in these relationships. On multivariate analysis, age (P = -0.54, P < .0 01), but not peak (V) over dot o(2) (beta = -0.01, P = .840), remained stro ngly associated with IGF-1 levels. After adjustment of peak (V) over dot o( 2) for FFM in subjects with DEXA scans, results were similar. CONCLUSIONS: These findings indicate that although both peak aerobic capaci ty and circulating IGF-1 levels decline with age, aerobic capacity is not i ndependently related to circulating IGF-1 in healthy men and women across t he adult life span.