A Method for Determining Body Weight Replacement Load during Squat Exercise in Weightlessness



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47th International Conference on Environmental Systems


Studies on Astronauts in Mir space station has confirmed a loss of 1-2% in bone mass density for each month.They are prone to lose as much as 20% of their bone strength in their lower body which includes pelvis, hip bone, legs and feet over a six month duration of space flight. The prime focus of this research is to optimize exercise prescriptions for astronauts in reduced gravity in terms of bone and muscle loading for body weight squat. The study involved motion capture data collection from four female subjects while performing a body weight squat at Human Systems and Simulations Laboratory (HSSL) at University of Cincinnati. In 1g environment, the normalized peak muscle forces are 14.3 N/kg in gluteal muscle group, 5.6 N/kg in hamstrings, 35.9 N/kg in quadriceps and 32.4 N/kg in calf muscle group. The normalized peak joint reaction loads are 35.6 N/kg at hip joint, 46.4 N/kg at knee joint, 95.5 N/kg at ankle joint and 16.7 N/kg at lumbar joint. In weightless environment, bone and muscle forces are significantly less due to which the bone and muscle strength deteriorates. This study aims at optimizing the application of external loads on the subject such that it generates similar bone and muscle forces as in 1g. It includes varying the external loads at shoulders from 50% BW to 150% BW with 10% increments. Further, a novel approach is proposed and implemented to determine optimal external load to be applied. This body weight replacement (BWR) load for producing comparable joint moments as in 1g is 71% BW applied at shoulders. This external load is 84% BW for muscle forces and 76% for joint reaction loads.


Satya Sri Mummidivarapu, Autoliv Americas, USA
Grant Schaffner, University of Cincinnati, USA
ICES513: Computational Modeling for Human Health and Performance Analysis
The 47th International Conference on Environmental Systems was held in South Carolina, USA on 16 July 2017 through 20 July 2017.


Bone mass density, reduced gravity, squat, joint, moments, muscle forces, joint loads, body weight replacement load