Submitted on July 16, 2007
Accepted on September 13, 2007
Hypergravity resistance exercise: the use of artificial gravity as potential countermeasure to microgravity
Yifan Yang1, Michael J. Baker2, Scott C. Graf3, Jennifer K. Larson3, and Vincent J. Caiozzo4*
1 Department of Orthopedic Surgery, University of California, Irvine, Irvine, California, United States
2 Department of Orthopedic Surgery, Univeristy of California, Irvine, Irvine, California, United States
3 General Clinical Research Center, University of California, Irvine, Irvine, California, United States
4 Department of Orthopedic Surgery, University of California, Irvine, Irvine, California, United States; Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, United States
* To whom correspondence should be addressed. E-mail: vjcaiozz{at}uci.edu.
INTRODUCTION: The aims of this study were to 1) determine if hypergravity (HG) squats can produce foot forces similar to those measured during 10-repetition maximum (10RM) squats using weights under normal 1 Gz condition, and 2) compare the kinematics (duration and goniometry) and electromyographic (EMG) activities of selected joints and muscles, between 10RM and HG squats of similar total foot forces. METHODS: Eight men and 6 women [27 yr (SD 4), 66 kg (SD 10)] completed ten 10RM [83 kg (SD 23)] and 10 HG squats (2.25 to 3.75 Gz). HG squats were performed on a human powered short-arm centrifuge. Foot forces were measured using insole force sensors. Hip, knee and ankle angles were measured using electrogoniometers. EMG activities of the erector spinae, bicep femoris, rectus femoris and gastrocnemius were also recorded during both squats. RESULTS: All subjects were able to achieve similar or higher average total foot forces during HG squats compared to those obtained during 10RM squats. There were no differences in total duration per set, average duration per repetition, and goniometry and EMG activities of the selected joints and muscles, respectively between 10RM and HG squats. CONCLUSIONS: These results demonstrate that HG squats can produce very high foot forces that are comparable to those produced during 10RM squats at 1 Gz. In addition, the technique and muscle activation are similar between the two types of squats. This observation supports the view that HG resistance training may represent an important countermeasure to microgravity.
