Journal
AVIATION SPACE AND ENVIRONMENTAL MEDICINE
Volume 85, Issue 7, Pages 694-699Publisher
AEROSPACE MEDICAL ASSOC
DOI: 10.3357/ASEM.3856.2014
Keywords
exercise countermeasures; PFK; PGC-1 alpha; unilateral lower limb unloading; human spaceflight
Funding
- Swedish National Space Board (SNSB)
- European Space Agency (ESA)
- National Aeronautics and Space Administration (NASA) [5286]
Ask authors/readers for more resources
Background: As spaceflight compromises skeletal muscle oxidative and aerobic work capacity, this study assessed the efficacy of resistance exercise (RE) to counteract muscle metabolic perturbations induced by 5 wk unilateral lower limb unloading (UL). Methods: There were 21 men and women (30-56 yr) who were randomly assigned to either UL with (Group, Grp; UL+RE; N = 10) or without (Grp UL; N = 11) concurrent RE. Iso-inertial RE comprised four sets of seven maximal coupled concentric-eccentric knee extensions executed 2-3 times per week. Percutaneous biopsies were obtained from m. vastus lateralis before and after either intervention. Levels of mRNA expression of factors regulating skeletal muscle oxidative capacity, i.e., peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1 alpha) and vascular endothelial growth factor (VEGF), and glycolytic capacity, i.e., phosphofructokinase (PFK), glycogen phosphorylase and synthase, hexokinase, and phosphorylase kinase alpha 1, were subsequently analyzed. Results: Grp UL showed decreased (36%) PGC-1 alpha expression, increased (1.5-fold) PFK expression, and a trend toward decreased VEGF post-intervention. Grp UL+RE showed no changes. Discussion: These results suggest that 5 wk unloading reduces skeletal muscle oxidative capacity and increases glycolytic enzyme activity. More importantly, only 12 bouts of high-force, low-volume resistance exercise attenuated these responses: Thus, the current resistance exercise paradigm emphasizing eccentric overload effectively counteracts unwarranted metabolic alterations induced by 5 wk unloading and may, therefore, aid in maintaining skeletal muscle integrity and endurance, and hence astronaut health and fitness during spaceflight.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available