A weightless environment causes astronauts to suffer muscle atrophy and reduced strength, and considerable attention has focused on identifying exercise prescriptions to reduce this loss. While evidence exists that resistance exercise is partially successful in reducing muscle atrophy, a definitive exercise prescription has not been identified that is suitable for conditioning skeletal muscle. In this animal study, Dr. Kenneth Baldwin’s goals are to determine the effectiveness of specific types of resistance exercises, to test and optimize exercises most effective at lessening atrophy, and to determine the effectiveness of resistance training in combination with pharmaceuticals (such as protease inhibiters), as compared to resistance training alone. Ultimately, the objective is to identify a resistance-training prescription that can be efficiently performed (minimizing time constraints), requires simple, yet reliable equipment devices, and is attractive to the astronauts for compliance.
Overview
Force Regulation as a Countermeasure to Muscle Atrophy
Principal Investigator:
Kenneth M. Baldwin, Ph.D.
Organization:
University of California, Irvine
Technical Summary
In recent years, considerable attention has focused on identifying exercise paradigms to ameliorate the deficits of atrophy and reduced strength in astronaut muscle properties, especially given that exposure to spaceflight is now minimally six months or longer on the International Space Station. While there is evidence that exercise of the resistance type is partially successful in reducing the muscle atrophy response, a definitive exercise prescription has not been identified that is suitable for conditioning skeletal muscle given the various constraints of microgravity that impact the homeostasis of astronauts.
Primary goals of the project are to utilize a rodent resistance-training model in order to:
- Ascertain the efficacy of acute bouts of isometric, concentric, eccentric and concentric-eccentric modes of contraction, as performed under conditions of muscle unloading, in their ability to activate molecular markers indicative of anabolic responses that have been shown to favor a positive protein balance profile in order to blunt the atrophy process;
- Test and optimize the most promising paradigm(s) for efficacy in ameliorating the atrophy of muscle associated with the model of hindlimb suspension; and
- Determine the efficacy of using resistance training, in combination with other pharmacological interventions (such as protease inhibiters), to ameliorate muscle atrophy-induced processes as compared to resistance training alone.
Ultimately, the objective is to identify a resistance-training prescription that can be efficiently performed (minimizing time constraints), requires simple, yet reliable equipment devices and is attractive to the astronauts for compliance.
Earth Applications
Our project provides insight on practical ways to improve muscle mass and lean body mass in both young and old individuals. It has application to sports training and as a means of helping aging individuals maintain strength in their limb muscles thus reducing accidents and injury. Furthermore, our findings indicate that sophisticated exercise modalities are not necessary for inducing muscle mass and strength. Extending this approach by using modes of exercise that can train the muscle for both endurance and strength will allow for a better prescription for conserving the homeostasis of skeletal muscle in the face of unloading stimuli.
This project's funding ended in 2008