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Applied horizontal force increases impact loading in reduced-gravity running
Y H Chang1, C M Hamerski, R Kram
1Locomotion Laboratory, Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA. younghui@yahoo.com
Journal of Biomechanics
|April 20, 2001
Summary
Astronauts experience bone loss in microgravity. Running with anterior horizontal forces (AHF) simulates Earth-like impact loading, potentially preventing bone degradation during spaceflight.
Area of Science:
- Space medicine
- Biomechanics
- Skeletal physiology
Background:
- Microgravity exposure causes lower limb bone structural degradation in astronauts.
- Current exercise countermeasures lack effectiveness in preventing this bone loss.
- Earth-based locomotion's impact loading maintains bone integrity, a factor missing in space.
Purpose of the Study:
- To investigate if running with anterior horizontal forces (AHF) can simulate Earth-like impact loads in reduced gravity.
- To test the hypothesis that AHF in simulated reduced gravity produces impact loads comparable to or exceeding those during normal Earth running.
- To evaluate AHF's potential as an exercise countermeasure against spaceflight-induced bone degradation.
Main Methods:
- Utilized a simulated reduced-gravity running model.
- Applied anterior horizontal forces (AHF) equivalent to 20% of gravity-specific body weight.
- Measured impact force peaks, loading rates, active force peaks, duty factor, and stride frequency.
Main Results:
- AHF significantly increased impact force peaks (74%), average impact loading rates (46%), and maximum impact loading rates (89%) compared to running without AHF.
- AHF did not substantially alter active force peaks.
- Duty factor and stride frequency showed modest decreases with AHF application.
Conclusions:
- Running with AHF in simulated reduced gravity successfully generated impact loads equal to or greater than those experienced during Earth gravity running.
- AHF can augment existing treadmill running exercise protocols for spaceflight.
- This approach shows promise for preventing musculoskeletal degradation in astronauts.