Forelimb joints contribute to locomotor performance in reindeer ( Rangifer tarandus ) by maintaining stability and storing energy

• Published in: PeerJ
• Main Authors: Li, Guoyu, Zhang, Rui, Han, Dianlei, Pang, Hao, Yu, Guolong, Cao, Qingqiu, Wang, Chen, Kong, Lingxi, Chengjin, Wang, Dong, Wenchao, Li, Tao, Li, Jianqiao
• Other Authors: National Natural Science Foundation of China, Science and Technology Development Planning Project of Jilin Province of China, Science and Technology Research Project in the 13th Five-Year Period of Education Department of Jilin Province
• Format: Article in Journal/Newspaper
• Language: English
• Published: PeerJ 2020
• Subjects: General Agricultural and Biological Sciences; General Biochemistry, Genetics and Molecular Biology; General Medicine; General Neuroscience; Rangifer tarandus
• Online Access: http://dx.doi.org/10.7717/peerj.10278; https://peerj.com/articles/10278.pdf; https://peerj.com/articles/10278.xml; https://peerj.com/articles/10278.html

Reindeer ( Rangifer tarandus ) have lengthy seasonal migrations on land and their feet possess excellent locomotor characteristics that can adapt to complex terrains. In this study, the kinematics and vertical ground reaction force (GRF) of reindeer forelimb joints (interphalangeal joint b , metacarpophalangeal joint c , and wrist joint d ) under walk, trot 1, and trot 2 were measured using a motion tracking system and Footscan pressure plates. Significant differences among different locomotor activities were observed in the joint angles, but not in changes of the joint angles ( α b , α c , α d ) during the stance phase. Peak vertical GRF increased as locomotor speed increased. Net joint moment, power, and work at the forelimb joints were calculated via inverse dynamics. The peak joint moment and net joint power related to the vertical GRF increased as locomotor speed increased. The feet absorbed and generated more energy at the joints. During different locomotor activities, the contribution of work of the forelimbs changed with both gait and speed. In the stance phase, the metacarpophalangeal joint absorbed more energy than the other two joints while trotting and thus performed better in elastic energy storage. The joint angles changed very little (∼5°) from 0 to 75% of the stance phase, which reflected the stability of reindeer wrist joints. Compared to typical ungulates, reindeer toe joints are more stable and the stability and energy storage of forelimb joints contribute to locomotor performance in reindeer.