Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
©Journal of Sports Science and Medicine (2021) 20, 766 - 777   DOI:

Research article
Muscle Actuators, Not Springs, Drive Maximal Effort Human Locomotor Performance
Jeffrey M. McBride 
Author Information
Neuromuscular & Biomechanics Laboratory, Beaver College of Health Sciences, North Carolina, USA

Jeffrey M. McBride
✉ Neuromuscular & Biomechanics Laboratory, Beaver College of Health Sciences, Department of Health & Exercise Science, Appalachian State University, Levine Hall 412A, Boone, North Carolina, USA
Publish Date
Received: 03-09-2021
Accepted: 20-09-2021
Published (online): 01-10-2021
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The current investigation examined muscle-tendon unit kinematics and kinetics in human participants asked to perform a hopping task for maximal performance with variational preceding milieu. Twenty-four participants were allocated post-data collection into those participants with an average hop height of higher (HH) or lower (LH) than 0.1 m. Participants were placed on a customized sled at a 20º angle while standing on a force plate. Participants used their dominant ankle for all testing and their knee was immobilized and thus all movement involved only the ankle joint and corresponding propulsive unit (triceps surae muscle complex). Participants were asked to perform a maximal effort during a single dynamic countermovement hop (CMH) and drop hops from 10 cm (DH10) and 50 cm (DH50). Three-dimensional motion analysis was performed by utilizing an infrared camera VICON motion analysis system and a corresponding force plate. An ultrasound probe was placed on the triceps surae muscle complex for muscle fascicle imaging. HH hopped significantly higher in all hopping tasks in comparison to LH. In addition, the HH group concentric ankle work was significantly higher in comparison to LH during all of the hopping tasks. Active muscle work was significantly higher in HH in comparison to LH as well. Tendon work was not significantly different between HH and LH. Active muscle work was significantly correlated with hopping height (r = 0.97) across both groups and hopping tasks and contributed more than 50% of the total work. The data indicates that humans primarily use a motor-driven system and thus it is concluded that muscle actuators and not springs maximize performance in hopping locomotor tasks in humans.

Key words: Tendon, hopping, biomechanics, ankle, titin

           Key Points
  • Humans use a predominance of active muscle contractility to enhance single maximal effort performance as opposed to tendon stored elastic energy
  • Single effort maximal performance in humans may entail a motor-driven system as opposed to a spring-driven system
  • However, the role of passive work (elastic components) from both muscle and tendon cannot be completely discounted as their contribution to performance may have activity dependent significance
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