Expression of IGF‐1a and change in muscle fiber area after 12 weeks of resistance training in elderly postoperative patients

Abstract

The mRNA splice variant of insulin‐like growth factor‐1a and the changes in muscle fiber cross sectional area after 12 weeks of rehabilitation, were studied in elderly postoperative patients. 28 subjects (age 60–86 yrs) were randomized to either resistance training (RT: 3/wk·12 wks), electrical stimulation (ES: 1 h/day·12 wks) or functional exercises (FE: 1 h/day·12 wks). Muscle biopsies were obtained from vastus lateralis (VL) of both legs at baseline, 5 and 12 wks post‐surgery to analyze for changes in mean muscle fiber area (MFA). Expression levels of IGF‐1a mRNA were determined using real‐time RT‐PCR and normalized to the Ribosomal Protein Large P0 (RPLP0) mRNA. There was no difference in MFA or resting levels of IGF‐1a between the three groups at baseline. RT resulted in a significant increase in IGF‐1a (+131 %, p<0.05) and MFA (+37%, p<0.05). In contrast, 12 weeks of ES and FE did not induce any change in MFA or in the expression of IGF‐1a. The present study is the first to demonstrate that resistance training initiated in the acute (1–2 days) postoperative phase is highly effective in increasing mean fiber area and in addition induced a marked increase in the expression of IGF‐1, supporting the idea that IGF‐1a may be involved in regulating muscle hypertrophy.Funded by the IMK Foundation and the Maersk McKinney Moller Foundation