Whole muscle contractile parameters and thickness loss during 35-day bed rest

Abstract

Extended exposure to microgravity leads to significant musculoskeletal adaptations. Contractile parameters of four skeletal muscles (biceps brachii-BB, vastus medialis-VM, biceps femoris-BF and gastrocnemius medialis-GM) were measured in ten healthy males (aged 22.3 +/- 2.2 years) during 35 days of horizontal bed rest by a mechanomyography-based method termed 'tensiomyography' (TMG). Two contractile parameters: contraction time (Tc) and maximal displacement (Dm) were individually measured from electrically evoked maximal single twitch TMG response of all four muscles before and after bed rest. Significant changes in Tc were found after bed rest, as shown by an increase in GM muscle Tc by 18% (p < 0.01). Dm values significantly increased (p < 0.01) after bed rest, by 24, 26 and 30% in the VM, BF and GM muscles, respectively. In the GM, the change in Dm significantly correlated with the decrease in muscle thickness (r = -0.70, p < 0.01). In conclusion, bed rest induced changes in both Dm and Tc of the TMG signal; changes in Dm being inversely related to those of muscle thickness. Amongst the investigated muscles, most affected, in terms of atrophy and mechanical alterations, were those of the lower limbs. The observed increase in Dm may be attributed to a decrease in muscle, as well as tendon stiffness, causing larger muscle fibre and non-contractile tissue oscillations following contraction.

Comportamiento neuromuscular posterior a la competencia en jugadores profesionales de fútbol de Costa Rica: un seguimiento tensiomiográfico

“…Lo anterior se respalda por Pisot et al, (2008), quienes rescatan que los efectos del reposo posterior a 35 días en cama producen un aumento del Dm y un aumento del Tc. Asimismo, la respuesta a la fatiga muestra un comportamiento similar, inmediatamente posterior a la participación de los atletas en una ultratriatlón (García-Manso et al, 2011), lo cual refleja un aumento de los valores de Dm y Tc para bíceps femoral, pero nuevamente no se muestran valores 24 horas posteriores a la actividad.…”

“…Por consiguiente, basado en los anterior se debe señalar que el J4 tuvo una particularidad con respecto a la LB, J1, J2 y J3, esto se podría explicar basándose en lo descrito por Rusu et al, (2013), quien indica que hay una respuesta aguda al entrenamiento en un lapso de 22 días de ejercicio físico contra resistencia, similar al tiempo en que transcurrieron las mediciones del presente estudio (24 días), hubo una disminución del Tc y un aumento del Dm. Las respuestas neuromusculares mencionadas anteriormente son respuestas contrarias a las señaladas por Pisot et al, (2008) (aumento de Tc y de Dm como respuesta al reposo prolongado), García-Manso et al, (2011) (aumento de Tc y Dm como respuesta inmediata a un evento de resistencia), (aumento del Tc y Dm 24 horas posterior a un maratón).…”

Tensiomyographic Characteristics of Rectus Femoris after a Single Bout of Intense Exercise

“…From all TMG parameters, Dm, Ts and Tr seem to provide the most useful information in evaluation of muscle fatigue (Krizaj et al, 2008). Dm, which could be equated to electrically evoked peak twitch torque, is determined by both the number and the type of muscle fibers recruited by the electrical stimulus, being considered as a measure of muscle belly stiffness (Pisot et al, 2008). In the present study TMG analysis of RF of right leg was performed before (pre-test) and after intense exercise (post-test), reported significant decreases in Dm and Td values, although no statistical differences were observed when Tr and Ts assessed in pre-test and posttest were compared.…”

“…In the last few years, measurements of contraction time by TMG have been successfully implemented on different muscle groups (Valencic and Knez, 1997) to investigate endurance and muscle belly stiffness among other muscular responses (Grabljevec et al, 2005;Pisot et al, 2008). However, muscle contractile properties during or after fatiguing exercise remains unclear (Letafatkar et al, 2009;Hosseinimehr et al, 2010) mainly due to a lack of adequate assay system.…”

MR elastography measurement of the effect of passive warmup prior to eccentric exercise on thigh muscle mechanical properties

“…MRE provides a direct quantitative measure of muscle belly stiffness by measurement of the complex shear modulus. Direct measurement of the muscle belly stiffness removes contributions from sources other than the muscle group in question, e.g., synergists and antagonist muscle groups, skin, ligaments, tendons, and articular structures,29 which may be a factor in other methodologies used to indirectly measure muscle stiffness such as range of motion analysis30 and tensiomyography (TMG) 31. MRE has previously been applied to muscle by Dresner et al,32 who showed that muscle stiffness increased with applied load, and Klatt et al,33 who showed that muscle stiffness increases linearly with strength of contraction.…”