Faculty Collaboration Database

The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation. Am J Physiol Cell Physiol 2007 Jul;293(1):C313-20

Date

04/06/2007

Pubmed ID

17409123

DOI

10.1152/ajpcell.00573.2006

Scopus ID

2-s2.0-34547101459 (requires institutional sign-in at Scopus site)   90 Citations

Abstract

Prolonged inactivity associated with bed rest in a clinical setting or spaceflight is frequently associated with hypercortisolemia and inadequate caloric intake. Here, we determined the effect of 28 days of bed rest (BR); bed rest plus hypercortisolemia (BRHC); and bed rest plus essential amino acid (AA) and carbohydrate (CHO) supplement (BRAA) on the size and function of single slow- and fast-twitch muscle fibers. Supplementing meals, the BRAA group consumed 16.5 g essential amino acids and 30 g sucrose at 1100, 1600, and 2100 h, and the BRHC subjects received 5 daily doses of 10-15 mg of oral hydrocortisone sodium succinate throughout bed rest. Bed rest induced atrophy and loss of force (mN) and power (muN.FL.s(-1)) in single fibers was exacerbated by hypercortisolemia where soleus peak force declined by 23% in the type I fiber from a prevalue of 0.78 +/- 0.02 to 0.60 +/- 0.02 mN post bed rest (compared to a 7% decline with bed rest alone) and 27% in the type II fiber (1.10 +/- 0.08 vs. 0.81 +/- 0.05 mN). In the BRHC group, peak power dropped by 19, 15, and 11% in the soleus type I, and vastus lateralis (VL) type I and II fibers, respectively. The AA/CHO supplement protected against the bed rest-induced loss of peak force in the type I soleus and peak power in the VL type II fibers. These results provide evidence that an AA/CHO supplement might serve as a successful countermeasure to help preserve muscle function during periods of relative inactivity.

Author List

Fitts RH, Romatowski JG, Peters JR, Paddon-Jones D, Wolfe RR, Ferrando AA

Author

Robert Fitts PhD Professor in the Biological Sciences department at Marquette University

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

Adult
Amino Acids, Essential
Bed Rest
Chronic Disease
Cushing Syndrome
Dietary Sucrose
Humans
Hydrocortisone
Male
Muscle Contraction
Muscle Fibers, Fast-Twitch
Muscle Fibers, Slow-Twitch
Muscle Strength
Muscle, Skeletal
Muscular Atrophy
Time Factors
Treatment Outcome