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


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.

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The data will be made available from the corresponding author on reasonable request.


  1. Aarts E, Verhage M, Veenvliet JV, Dolan CV, Van Der Sluis S (2014) A solution to dependency: using multilevel analysis to accommodate nested data. Nat Neurosci 17:491–496.

    CAS  Article  PubMed  Google Scholar 

  2. Alford EK, Roy RR, Hodgson JA, Edgerton VR (1987) Electromyography of rat soleus, medial gastrocnemius, and tibialis anterior during hind limb suspension. Exp Neurol 96(3):635–649.

    CAS  Article  PubMed  Google Scholar 

  3. Ashley-Ross MA (1995) Patterns of hind limb motor output during walking in the salamander Dicamptodon tenebrosus, with comparisons to other tetrapods. J Comp Physiol A 177:273–285

    Article  Google Scholar 

  4. Canu MH, Falempin M (1996) Effect of hindlimb unloading on locomotor strategy during treadmill locomotion in the rat. Eur J Appl Physiol Occup Physiol 74(4):297–304.

    CAS  Article  PubMed  Google Scholar 

  5. Canu MH, Falempin M (1997) Effect of hindlimb unloading on two hindlimb muscles during treadmill locomotion in rats. Eur J Appl Physiol Occup Physiol 75(4):283–288.

    CAS  Article  PubMed  Google Scholar 

  6. Canu MH, Garnier C (2009) A 3D analysis of fore- and hindlimb motion during overground and ladder walking: comparison of control and unloaded rats. Exp Neurol 218(1):98–108.

    Article  PubMed  Google Scholar 

  7. Canu MH, Falempin M, Orsal D (2001) Fictive motor activity in rat after 14 days of hindlimb unloading. Exp Brain Res 139(1):30–38.

    CAS  Article  PubMed  Google Scholar 

  8. Canu MH, Garnier C, Lepoutre FX, Falempin M (2005) A 3D analysis of hindlimb motion during treadmill locomotion in rats after a 14-day episode of simulated microgravity. Behav Brain Res 157(2):309–321.

    Article  PubMed  Google Scholar 

  9. Capogrosso M, Wagner FB, Gandar J, Moraud EM, Wenger N, Milekovic T et al (2018) Configuration of electrical spinal cord stimulation through real-time processing of gait kinematics. Nat Protoc 13:2031–2061.

    CAS  Article  PubMed  Google Scholar 

  10. Diogo R, Bello-Hellegouarch G, Kohlsdorf T, Esteve-Altava B, Molnar JL (2016) Comparative myology and evolution of marsupials and other vertebrates, with notes on complexity, bauplan, and “scala naturae.” Anat Rec (Hoboken) 299(9):1224–1255.

    Article  Google Scholar 

  11. Duysens J, Pearson KG (1980) Inhibition of flexor burst generation by loading ankle extensor muscles in walking cats. Brain Res 187(2):321–332.

    CAS  Article  PubMed  Google Scholar 

  12. English AW, Weeks OI (1987) An anatomical and functional analysis of cat biceps femoris and semitendinosus muscles. J Morphol 191(2):161–175.

    CAS  Article  PubMed  Google Scholar 

  13. Goudard I, Orsal D, Cabelguen JM (1992) An electromyographic study of the hindlimb locomotor movements in the acute thalamic rat. Eur J Neurosci 4(11):1130–1139.

    Article  PubMed  Google Scholar 

  14. Higham TE, Jayne BC (2004) In vivo muscle activity in the hindlimb of the arboreal lizard, Chamaeleo calyptratus: general patterns and the effects of incline. J Exp Biol 207(Pt 2):249–261.

    Article  PubMed  Google Scholar 

  15. Hodgson JA (1983) The relationship between soleus and gastrocnemius muscle activity in conscious cats–a model for motor unit recruitment? J Physiol 337:553–562.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  16. Hutchison DL, Roy RR, Hodgson JA, Edgerton VR (1989) EMG amplitude relationships between the rat soleus and medial gastrocnemius during various motor tasks. Brain Res 502(2):233–244.

    CAS  Article  PubMed  Google Scholar 

  17. Jayne BC, Irschick DJ (1999) Effects of incline and speed on the three-dimensional hindlimb kinematics of a generalized iguanian lizard (Dipsosaurus dorsalis). J Exp Biol 202:143–159

    Article  Google Scholar 

  18. Kaya M, Leonard T, Herzog W (2003) Coordination of medial gastrocnemius and soleus forces during cat locomotion. J Exp Biol 206(Pt 20):3645–3655.

    Article  PubMed  Google Scholar 

  19. Lauber B, Lichtwark GA, Cresswell AG (2014) Reciprocal activation of gastrocnemius and soleus motor units is associated with fascicle length change during knee flexion. Physiol Rep.

    Article  PubMed  PubMed Central  Google Scholar 

  20. Lawrence JH 3rd, Nichols TR, English AW (1993) Cat hindlimb muscles exert substantial torques outside the sagittal plane. J Neurophysiol 69(1):282–285.

    Article  PubMed  Google Scholar 

  21. Macpherson JM (1988) Strategies that simplify the control of quadrupedal stance. I. Forces at the ground. J Neurophysiol 60(1):204–217.

    CAS  Article  PubMed  Google Scholar 

  22. Molnar JL, Diogo R, Hutchinson JR, Pierce SE (2020) Evolution of hindlimb muscle anatomy across the tetrapod water-to-land transition, including comparisons with forelimb anatomy. Anat Rec (Hoboken) 303(2):218–234.

    Article  Google Scholar 

  23. Morey-Holton ER, Globus RK (2002) Hindlimb unloading rodent model: technical aspects. J Appl Physiol (1985) 92(4):1367–1377.

    Article  Google Scholar 

  24. Musienko P, van den Brand R, Märzendorfe O, Roy RR, Gerasimenko Y, Edgerton VR, Courtine G (2011) Controlling specific locomotor behaviors through multidimensional monoaminergic modulation of spinal circuitries. J Neurosci 31:9264–9278

    CAS  Article  Google Scholar 

  25. Ohira Y, Nomura T, Kawano F, Sato Y, Ishihara A, Nonaka I (2002) Effects of nine weeks of unloading on neuromuscular activities in adult rats. J Gravit Physiol 9(2):49–59

    PubMed  Google Scholar 

  26. Pearson KG, Ramirez JM, Jiang W (1992) Entrainment of the locomotor rhythm by group Ib afferents from ankle extensor muscles in spinal cats. Exp Brain Res 90(3):557–566.

    CAS  Article  PubMed  Google Scholar 

  27. Philippson M (1905) L’autonomie et la centralisation dans le syst`eme nerveux des animaux. Trav Lab Physio Inst Solvay (Bruxelles) 7:1–208

    Google Scholar 

  28. Popov A, Lyakhovetskii V, Bazhenova E, Gorskii O, Kalinina D, Merkulyeva N, Musienko P (2021) The role of the load-dependent sensory input in control of balance during gait. J Exp Biol. jeb.242138:

  29. Roy RR, Hutchison DL, Pierotti DJ, Hodgson JA, Edgerton VR (1991) EMG patterns of rat ankle extensors and flexors during treadmill locomotion and swimming. J Appl Physiol 70(6):2522–2529.

    CAS  Article  PubMed  Google Scholar 

  30. Smith JL, Betts B, Edgerton VR, Zernicke RF (1980) Rapid ankle extension during paw shakes: selective recruitment of fast ankle extensors. J Neurophysiol 43(3):612–620.

    CAS  Article  PubMed  Google Scholar 

  31. Suzuki T, Chino K, Fukashiro S (2014) Gastrocnemius and soleus are selectively activated when adding knee extensor activity to plantar flexion. Hum Mov Sci 36:35–45.

    Article  PubMed  Google Scholar 

  32. Tachibana A, McVea DA, Donelan JM, Pearson KG (2006) Recruitment of gastrocnemius muscles during the swing phase of stepping following partial denervation of knee flexor muscles in the cat. Exp Brain Res 169(4):449–460.

    CAS  Article  PubMed  Google Scholar 

  33. Tajino J, Ito A, Nagai M, Zhang X, Yamaguchi S, Iijima H, Aoyama T, Kuroki H (2015) Intermittent application of hypergravity by centrifugation attenuates disruption of rat gait induced by 2 weeks of simulated microgravity. Behav Brain Res 287:276–284.

    Article  PubMed  Google Scholar 

  34. Templeton GH, Padalino M, Manton J, Glasberg M, Silver CJ, Silver P, DeMartino G, Leconey T, Klug G, Hagler H et al (1984) Influence of suspension hypokinesia on rat soleus muscle. J Appl Physiol Respir Environ Exerc Physiol 56(2):278–286.

    CAS  Article  PubMed  Google Scholar 

  35. Walmsley B, Hodgson JA, Burke RE (1978) Forces produced by medial gastrocnemius and soleus muscles during locomotion in freely moving cats. J Neurophysiol 41(5):1203–1216.

    CAS  Article  PubMed  Google Scholar 

  36. Winiarski AM, Roy RR, Alford EK, Chiang PC, Edgerton VR (1987) Mechanical properties of rat skeletal muscle after hind limb suspension. Exp Neurol 96(3):650–660

    CAS  Article  Google Scholar 

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This work was performed within project ID: 73025408 of the St. Petersburg State University, St. Petersburg, Russia (for N.M.), supported by the Russian Foundation for Basic Research grant №17-29-01034_ofi_m (for electrophysiological testing), Grant № 20-015-00568 (for the data analysis). We thank the following people for their help and expertise: O.V. Gorskii (technical support for experimental setup), E.Y. Bazhenova (care and technical assistance with the animals), Olga Ptitsyna (design and layout of figures).

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AP and PM conceived and designed the experiments; AP and PM performed the research; AP and VL analyzed the data; AP wrote the first draft of the paper; AP, VL, NM and PM revised and approved the final manuscript PM supervised the study.

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Correspondence to Musienko Pavel.

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Alexander, P., Vsevolod, L., Natalia, M. et al. Effect of hindlimb unloading on recruitment of gastrocnemius medialis muscle during treadmill locomotion in rats. Exp Brain Res 239, 2793–2801 (2021).

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  • Hindlimb unloading
  • Locomotion
  • Gastrocnemius medialis muscle
  • Rat