Effects of treadmill running on rat gastrocnemius function following botulinum toxin A injection

Abstract

Exercise can improve and maintain neural or muscular function, but the effects of exercise in physiological adaptation to paralysis caused by botulinum toxin A has not been well studied. Twenty-four rats were randomly assigned into control and treadmill groups. The rats assigned to the treadmill group were trained on a treadmill three times per week with the running speed set at 15 m/min. The duration of training was 20 min/session. Muscle strength, nerve conduction study and sciatic functional index (SFI) were used for functional analysis. Treadmill training improved the SFI at 2, 3, and 4 weeks (p = 0.01, 0.004, and 0.01, respectively). The maximal contraction force of the gastrocnemius muscle in the treadmill group was greater than in the control group (p < 0.05). The percentage of activated fibers was higher in the treadmill botox group than the percentage for the control botox group, which was demonstrated by differences in amplitude and area of compound muscle action potential (CMAP) under the curve between the groups (p < 0.05). After BoNT-A injection, treadmill improved the physiological properties of muscle contraction strength, CMAP amplitude, and the recovery of SFI.

An acellular biologic scaffold does not regenerate appreciable de novo muscle tissue in rat models of volumetric muscle loss injury

“…In this study, rats with VML injured muscle repaired with a porcine UBM scaffold were subjected to physical rehabilitation (i.e., voluntary wheel running) beginning either one week or four weeks postinjury. Physical rehabilitation has been shown to foster regeneration of injured muscle using muscle grafts [7,56,57], and is postulated to improve ECM mediated tissue remodeling [42,58,59]. However, in this study, regardless of the time of initiation of physical rehabilitation, neither muscle fiber regeneration nor function of the porcine UBM scaffold repaired muscles improved compared to no rehabilitation.…”

“…It is possible that a different modality or a prescribed running regimen may elicit performance improvements. However, in recognition of the literature [7,56,57], the current results underscore that the efficacy of physical rehabilitation is likely to increase synergy only when appreciable de novo muscle tissue regeneration is realized.…”

Molecular Mechanisms of Treadmill Therapy on Neuromuscular Atrophy Induced via Botulinum Toxin A

“…Studies showed that muscle mass following BoNT-A injection was reduced by approximately 70% to 30% within 1 to 6 months [82–84]. A 30% to 90% (approximately) reduction in muscle force was reported in animal studies [83, 85–87].…”

“…The reduction in CMAP parallels the decrease in the mean rectified voltage during a maximal voluntary contraction [101]. A recent study showed that the CMAP amplitude was significantly reduced, while no changes of distal latency were found in the gastrocnemius following a BoNT-A injection for 4 weeks [84]. This result was compatible with the results of a previous study demonstrating that an injection of BoNT-A caused localized muscle paralysis but no disruption in axonal transport [102].…”

“…In the treadmill training model, different training paradigms have been used. Some groups use ramp protocols [106], and others use the model with a consistent speed and exercise duration [84, 107]. The advantage of treadmill training is that the animals can be made to exercise at a desirable training intensity and duration.…”