Estimation of Gait Characteristics during Walking in Lower Gravity Environment Using a Wearable Device

Abstract

Event Abstract Back to Event Estimation of Gait Characteristics during Walking in Lower Gravity Environment Using a Wearable Device Léo Lamassoure1*, Keisuke Araki1, Akihito Ito1, Kiyotaka Kamibayashi1, Yoshinobu Ohira1 and Nobutaka Tsujiuchi1 1 Doshisha University, Japan Abstract Responses of walking patterns at 3.5 km/h and 0% inclination in 8 male subjects to reduction of body weight were estimated using a lower body positive pressure (LBPP) treadmill. Gait patterns and ground reaction forces (GRF) were estimated using a wearable device for motion analysis. In response to the reduction of body weight, the GRFs lowered accordingly. The gait patterns shifted from rear-foot strike to fore-foot strike, especially when the body weight was reduced from 60 to 40% vs. the 1-G condition. Further, the angle of ankle joints increased and that of knee joints and the movement ranges of hip joint were decreased, on the contrary. Introduction New space missions to The Moon and Mars are planned. In this context, a better understanding of the influence of low-gravity environments on gait characteristics is required (3/8-G) [1-3]. In a previous experiment, electromyogram activities and joint angles were measured during walking and/or running on a LBPP treadmill [4, 5]. It clearly indicated that the mobilization of the ankle plantar-flexor, slow-twitch, and soleus muscles was reduced in response to the gravitational unloading. However the close relationship between these parameters and the ground reaction forces was still unclear. Therefore, the current study was performed to investigate the walking patterns, including ground reaction force and gait patterns during walking on a LBPP treadmill using a wearable device [5, 6]. Methods Eight healthy male students volunteered as subjects (height: 170 ± 5 cm, weight: 70.9 ± 5.4 kg). The Human Use Committees at Doshisha University approved the study. All experimental procedures were conducted in accordance with World Medical Association Declaration of Helsinki (Ethical Principles for Medical Research Involving Human Subjects). The wearable devices were composed of sandal-type shoes each equipped with two forceplates in their soles, and of sensors for joint angles (acceleration, gyroscopes, and geomagnetic). The subjects were equipped with the wearable devices (sampling frequency 100 Hz) and walked for 60 sec at 3.5 km/h and 0% inclination with 100, 80, 60, 40, or 20% body weight support on a LBPP treadmill (AlterG Inc., USA). The levels of loading were assigned randomly for each subject. Results The normalized GRFs reduced gradually with the body weight (BW) (Fig. 1). The level of the GRF at toe-off was slightly greater than that at touch down, when the body-weight support was 100-60%. But it was reversed following further decrease below 40%. Joint angles were affected differently by the reduction of the BW. For the ankle, the absolute value of the plantar flexion peak increased when the BW was reduced, especially between 60 and 40% of BW. For the knee, the peak value of the flexion angle reduced, especially at the 60-40% and 40-20% transitions. For the hip joint, the movement range decreased, most significantly below 60% of BW. An increase in the total duration of the average gait cycle also appeared with the reduction of the BW. Figure 1 shows clearly that the duration of the stance phase remained the same for all weight rates, but the swing phase got longer as the weight rate decreased. Discussion These results explain more precisely the evolution of the gait pattern observed on subjects walking at low weight rates. For the ankle, the increase of the plantar flexion peak could explain the shift in foot-strike pattern that happens at low weight rates, while the lengthening of the swing phase observed is in accord with previous research [6, 7]. The ANOVA results indicate that the changes in joint angles are mostly significant when changing from 60% to 40% of BW, suggesting it is between these two weight rates that the gait transition happened. Conclusion In response to the reduction of body weight, the GRFs were lowered accordingly. The gait patterns were shifted from rear-foot to fore-foot strike, especially when the body weight was reduced from 60 to 40% vs. the 1-G condition. Further, the angle of ankle joints was increased and that of knee joints and the movement ranges of hip joint were decreased, on the contrary. Figure 1 Acknowledgements This study was, in part, supported by the Grant-in-Aid for Scientific Research (B, JP17H03193, N.T.) from Japan Society for the Promotion of Science.