Inverse Dynamics Analysis for Squat Exercise on a Human Centrifuge

Kurzfassung

This study is a part of the ExRoTe study (Exercise Performance with the Body Mass Accelerated by Rotation Compared with the Acceleration by the Terrestrial Gravitational Field) at the Institute of Aerospace Medicine, German Aerospace Center (DLR). As squat is a resistive exercise that has significant musculoskeletal and cardiovascular benefits when combined with artificial gravity (AG), it is a potential countermeasure to the physiological deconditioning that results from long-duration spaceflight. However, body movements on a rotating short-arm human centrifuge are affected by the gravity gradient and Coriolis accelerations. The biomechanical responses including leg kinematics, foot reaction forces, joint torques, and muscle activities of squat exercise while lying supine on a human centrifuge were investigated and compared with 1-G upright squats on Earth. The purpose of this study is to develop the biomechanical model and simulation for squat exercise on a short-radius human centrifuge for predicting foot reaction forces, the effects of the Coriolis accelerations and gravity Gradient acting on the body during the exercise, and estimating joint torques in order to provide safe and effective artificial gravity squat exercise protocols for future human missions to distant destinations such as the Moon and Mars. In order to validate the model and simulation, the human measurements and squat experiments were conducted on the next generation DLR ShortArm Human Centrifuge (envifuge) and on the ground control station to collect the data of 8 subjects (4 males and 4 females). All of the subjects were healthy at age between 20 and 50 years, height between 1.58 and 1.90 meters, weight between 50 and 100 kilograms, and BMI between 18 and 28. Motion capturing system, force plates and accelerometers were the main equipment used for collecting the data. This research furthered our nderstanding of the behavior of the musculoskeletal system in an artificial gravity environment, human kinematics and dynamics, and the effects of the Coriolis accelerations and gravity gradient acting on the body during the artificial gravity squat exercise. For the next generation DLR Short-Arm Human Centrifuge (envifuge), it was the first time that the basic vital parameters in this context were observed and recorded. Furthermore, using inverse dynamics method to develop a biomechanical model and simulation for artificial gravity squat exercise that demonstrate foot reaction forces, joint torques, and body movements and deflections due to the Coriolis effect and g-gradient with the adjustable input parameters including radius of the centrifuge, rotation rate, and test subject’s height, weight, and lengths of body parts, was new knowledge and would be very beneficial to the further artificial gravity squat exercise studies as well as other exercises such as hopping, jumping, or cycling along with the studies on cardiovascular system during short-radius centrifugation. Moreover, it may also lead to developing, improving, and standardizing artificial gravity exercise protocols, operations and safety of various centrifuges.