Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine (2023) 22, 582 - 590   DOI: https://doi.org/10.52082/jssm.2023.582

Research article
Mechanics of The Medial Gastrocnemius–Tendon Unit in Behaving more Efficiently in Habitual Non-Rearfoot Strikers than in Rearfoot Strikers during Running
Liqin Deng1, Xini Zhang1,2, Boyi Dai3, Songlin Xiao1, Faning Zhang1, Weijie Fu1, 
Author Information
1 Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, China
2 Faculty of Sports Science, Ningbo University, China
3 Division of Kinesiology and Health, University of Wyoming, USA

Weijie Fu
✉ PhD Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, 200438 Shanghai, China
Email: fuweijie@sus.edu.cn
Publish Date
Received: 27-03-2023
Accepted: 28-08-2023
Published (online): 01-09-2023
 
 
ABSTRACT

This study aims to quantify how habitual foot strike patterns would affect ankle kinetics and the behavior and mechanics of the medial gastrocnemius–tendon unit (MTU) during running. A total of 14 runners with non-rearfoot strike patterns (NRFS) and 15 runners with rearfoot strike patterns (RFS) ran on an instrumented treadmill at a speed of 9 km/h. An ultrasound system and a motion capture system were synchronously triggered to collect the ultrasound images of the medial gastrocnemius (MG) and marker positions along with ground reaction forces (GRF) during running. Ankle kinetics (moment and power) and MG/MTU behavior and mechanical properties (MG shortening length, velocity, force, power, MTU shortening/lengthening length, velocity, and power) were calculated. Independent t-tests were performed to compare the two groups of runners. Pearson correlation was conducted to detect the relationship between foot strike angle and the MTU behavior and mechanics. Compared with RFS runners, NRFS runners had 1) lower foot strike angles and greater peak ankle moments; 2) lower shortening/change length and contraction velocity and greater MG peak force; 3) greater MTU lengthening, MTU shortening length and MTU lengthening velocity and power; 4) the foot strike angle was positively related to the change of fascicle length, fascicle contraction length, and MTU shortening length during the stance phase. The foot strike angle was negatively related to the MG force and MTU lengthening power. The MG in NRFS runners appears to contract with greater force in relatively isometric behavior and at a slower shortening velocity. Moreover, the lengthening length, the lengthening velocity of MTU, and the MG force were greater in habitual NRFS runners, leading to a stronger stretch reflex response potentially.

Key words: Foot strike pattern, medial gastrocnemius, muscle contraction, ultrasound


           Key Points
  • The medial gastrocnemius of habitual non-rearfoot strike pattern runners appear to contract with the MG producing greater force in relatively isometric behavior and at a slower shortening velocity.
  • The greater shortening and lengthening length and the lengthening velocity of the medial gastrocnemius-tendon unit of habitual non-rearfoot strikers could potentially lead to a stronger stretch reflex response during running.
 
 
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