TY - JOUR

T1 - Effect of hindlimb unloading on recruitment of gastrocnemius medialis muscle during treadmill locomotion in rats

AU - Попов, Александр Анатольевич

AU - Ляховецкий, Всеволод Александрович

AU - Меркульева, Наталья Сергеевна

AU - Мусиенко, Павел Евгеньевич

N1 - Publisher Copyright: © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

PY - 2021/9

Y1 - 2021/9

N2 - After hindlimb unloading (HU), the adaptive changing of the rat step cycle duration, kinematics of the ankle and knee joints, and duration of one-joint ankle extensor m. soleus (SOL) activity are detected. However, how the activity of their synergist gastrocnemius medialis muscle (GM) changes in locomotion after HU remains unknown. GM is a two-joint muscle that produces both extension and flexion torques at the ankle and knee, respectively, regardless of the step cycle phase. The aim of our study was to assess changes in the flexor and extensor activity of GM and their influence on hindlimb kinematics after HU. The hindlimb kinematics, activity of GM, and SOL were evaluated, and semitendinosus muscle (ST) activity was registered in six Wistar rats in treadmill locomotion before and after HU. The mean EMG of the GM activity, which was co-active with ST burst activity, significantly increased after HU. The mean EMG of the GM activity, which was co-active with SOL activity, was unchanged after HU, but both SOL and GM bursts had a tendency to increase in duration. Hyperextension of the knee joint and the tendency to overextension of the ankle joint in the late of the stance phase were revealed after HU. The results show that the absence of weight bearing leads to an increase only in the flexor activity of GM and does not affect the extensor GM activity. Possible mechanisms of changes in GM activity and joint kinematics after HU are discussed.

AB - After hindlimb unloading (HU), the adaptive changing of the rat step cycle duration, kinematics of the ankle and knee joints, and duration of one-joint ankle extensor m. soleus (SOL) activity are detected. However, how the activity of their synergist gastrocnemius medialis muscle (GM) changes in locomotion after HU remains unknown. GM is a two-joint muscle that produces both extension and flexion torques at the ankle and knee, respectively, regardless of the step cycle phase. The aim of our study was to assess changes in the flexor and extensor activity of GM and their influence on hindlimb kinematics after HU. The hindlimb kinematics, activity of GM, and SOL were evaluated, and semitendinosus muscle (ST) activity was registered in six Wistar rats in treadmill locomotion before and after HU. The mean EMG of the GM activity, which was co-active with ST burst activity, significantly increased after HU. The mean EMG of the GM activity, which was co-active with SOL activity, was unchanged after HU, but both SOL and GM bursts had a tendency to increase in duration. Hyperextension of the knee joint and the tendency to overextension of the ankle joint in the late of the stance phase were revealed after HU. The results show that the absence of weight bearing leads to an increase only in the flexor activity of GM and does not affect the extensor GM activity. Possible mechanisms of changes in GM activity and joint kinematics after HU are discussed.

KW - Gastrocnemius medialis muscle

KW - Hindlimb unloading

KW - Locomotion

KW - Rat

KW - WALKING

KW - LIZARD

KW - ANKLE EXTENSOR MUSCLES

KW - PATTERNS

KW - FORCES

KW - MODEL

KW - SOLEUS

UR - http://www.scopus.com/inward/record.url?scp=85110324470&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/1b59eee5-67ea-3241-b706-ef6faccc6e5c/

U2 - 10.1007/s00221-021-06167-9

DO - 10.1007/s00221-021-06167-9

M3 - Article

VL - 239

SP - 2793

EP - 2801

JO - Experimental Brain Research

JF - Experimental Brain Research

SN - 0014-4819

IS - 9

ER -