Effect of Exercise-induced Muscle Damage on Neuromuscular Function of the Quadriceps Muscle

Abstract

Exercise-induced muscle injury is commonly accompanied by a reduction of muscular strength. It has been suggested that this reduction in voluntary force is attributable to "peripheral" and "central" mechanisms within the neuromuscular system. The quadriceps muscle of 15 subjects was damaged with four bouts of 25 maximal voluntary concentric-eccentric contractions at a speed of 60°/s. In a time period of 7 days, we investigated the contribution of agonist muscle activation and contractile properties (CP) to changes in isometric maximum voluntary torque (iMVT). In order to provide a comprehensive assessment, the neural drive to muscles was estimated with the interpolated twitch technique and root mean square of the EMG signal. CP were evaluated by analysing the twitch torque signal induced by single and doublet stimulation. Furthermore, we measured changes in alpha motoneuron excitability of vastus medialis at the spinal level due to muscle soreness using the H reflex technique. The iMVT was impaired at post, 24 h and 48 h, while rate of torque development and voluntary activation (VA) were only decreased immediately after the intervention. CP were impaired immediately after exercise and at 24 h. Maximal H reflex (Hmax), maximal M wave (Mmax) and the Hmax/Mmax-ratio were not affected. Sensation of muscle soreness assessment revealed impairments at 24 h, 48 h and 72 h. Data suggest that reduced VA and altered CP contribute to the force loss immediately after concentric-eccentric exercise. Thereafter, the impairment of CP seems to be mainly responsible for the reduced iMVT. In addition, there is no evidence for an association between muscle soreness and VA as well as between muscle soreness and spinal excitability.

Time-course of recovery of peak oxygen uptake after exercise-induced muscle damage

“…Additionally, the slowing of +dT/dt was consistent with previous studies (Behrens et al, 2012;Sayers et al, 2003) and could be the result of impairments in excitationcontraction coupling (Warren et al, 1993) and/or a shift in the length-tension relationship such that maximal force production would occur at longer muscle lengths (Prasartwuth et al, 2006). In agreement with previous findings (Behrens et al, 2012;Hubal et al, 2007), motor-unit recruitment was unaffected by EIMD in the present study-suggesting muscle soreness/pain did not prevent participants from fully activating/recruiting the damaged muscle group. The reductions in TT and +dT/dt in combination with no changes in%ACT support the idea damage to the contractile apparatus was the primary factor contributing to the observed declines in strength.…”

Peak power is reduced following lengthening contractions despite a maintenance of shortening velocity

“…A potential key component that may contribute to the impaired power production following lengthening contractions is the rate of torque development (RTD) (Andersen and Aagaard 2006). The reduction in MVC following fatigue or lengthening contractions is associated with impaired RTD (Behrens et al 2012;Crameri et al 2007;Hannah et al 2012), and this would be manifested during dynamic contractions such that the ensuing angular velocity and power production will be reduced when the contractile torque equals and then exceeds the specific isotonic load.…”

Ipsilateral resistance exercise prevents exercise-induced central sensitization in the contralateral limb: a randomized controlled trial

“…The NWRT can be considered as an outcome measure reflecting centrally mediated mechanisms, while local (i.e., TA muscle) muscle oxygenation can be seen as a peripherally (localized) mediated mechanism. Previous studies demonstrated the RBE on isolated eccentric contraction of elbow flexors (Muthalib et al 2011) and knee extensors (Behrens et al 2012), but no previous study has examined the contralateral repeated bout effect of TA. In the present study, TA muscle was chosen due to its muscle action, fiber composition, and activation profile (Johnson et al 1973;Madeleine et al 2006) and also because of its appropriateness for NWR recordings (Andersen 2007).…”