ß₂ Agonist Administration and Resistance Exercise as a Combined Countermeasure for the Antigravity Musculature During Simulated Microgravity

Co-PIs: Dr. John W. Williams, Krug Life Sciences, NASA/Johnson Space Center
B. J. McKenzie, M.D., Student Health Services, Montana State University

The project combines ß₂ agonist administration with resistance exercise as a countermeasure to ameliorate simulated (unilateral limb suspension-ULLS) space flight losses to the antigravity musculoskeleton. Employing a double-blind design, eight nonasthmatics will be randomized into one of two groups (placebo or ß₂) prior to 40 days of ULLS. Subjects will concurrently train their left (unweighted) leg's knee and ankle extensors 2-3 times per week on an inertial resistance ergometer. Pre (week 0) and post (week 6) dual energy x-ray absorptiometry (DEXA) whole body and regional scans will examine bone mineral density (BMD) in the unweighted leg. Pre (week 0), mid (week 3), and post (week 6) cross-sectional area (CSA), electromyography (EMG), and antigravity strength analyses will quantify muscle performance and morphology. Subjects will ingest the maximal therapeutic dosage (16 mg/day) of the ß₂ agonist (albuterol) or the placebo (lactose) by four capsule administrations. Strength testing consists of one set of eight maximal repetitions to volitional fatigue. Statistical analysis employs a 2x3 MANCOVA on strength data, covarying performance with profile of mood states (POMS) scores. A 2x3 ANOVA will examine the unweighted leg's CSA and EMG mearsures. Finally a 2x2 ANOVA will examine BMD changes to the unweighted leg's weight-bearing skeletal segments. This study will help determine if combining treatments is an effective countermeasure to musculoskeletal deconditioning using a 40 day space flight analog.

Juan Aybar is pictured here exercising his unweighted leg on the YoYo Strength Ergometer while Dr. Caruso counts repetitions.

Contact Information

Mail:	Dr. John F. Caruso
	Department of Health Ecology/274
	217 Lombardi Building
	University of Nevada-Reno
	Reno, NV 89557-0036
E-mail:	caruso@unr.edu