Net energy expenditure of gravity-independent high-speed resistive exercise done by women.
BACKGROUND
Elevated metabolism is common to spaceflight while exercise in microgravity exacerbates energy costs. Thus in-flight exercise countermeasures must be devised that minimize energy costs as they are performed on hardware operable in microgravity.


METHODS
Female subjects (N = 28), subdivided into athletic and sedentary groups, each performed two workouts on a resistive exercise device (Impulse Training Systems; Newnan, GA). Comprised exclusively of either tonic or phasic repetitions, each exercise bout entailed two 1 -min sets interspersed by a 90-s rest from which the work volume was determined. Oxygen consumption was measured before, during, and after workouts until gas uptake returned to pre-exercise levels. Net oxygen consumption was converted to net energy expenditures via indirect calorimetry. Mean net energy expenditure and work volume values were each compared with 2 (athletes, sedentaries) x 2 (tonic, phasic) ANOVAs, with repeated measures for workout. In addition, multivariate regression employed three predictor (body mass, body fat percentage, work volume) variables to account for the net energy expenditure variance.


RESULTS
Workouts yielded a metabolic cost of approximately 14 kcal, yet the data produced no significant intergroup or workout differences. However, work volume analysis yielded a significant (tonic > phasic) effect. The multivariate analysis explained small yet significant amounts of net energy expenditure variance.


CONCLUSIONS
Current results: 1) are partly attributable to higher series elastic element activity seen with Impulse repetitions; and 2) offer new information with respect to in-flight exercise protocols for female astronauts.
Exercise and Sport Science Program, The University of Tulsa, OK 74104, USA. john-caruso@utulsa.edu
John F
JF
Caruso
Jake A
JA
Borgsmiller
Rebekah D
RD
Riner
Melissa L
ML
Mason
Brant R
BR
Lutz
Colbert C
CC
Nelson
D000704:Analysis of Variance; D056352:Athletes; D002153:Calorimetry, Indirect; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D015999:Multivariate Analysis; D010101:Oxygen Consumption / Q000502:physiology; D055070:Resistance Training; D057185:Sedentary Behavior; D055815:Young Adult