Effects of icing or heat stress on the induction of fibrosis and/or regeneration of injured rat soleus muscle

Abstract

The effects of icing or heat stress on the regeneration of injured soleus muscle were investigated in male Wistar rats. Bupivacaine was injected into soleus muscles bilaterally to induce muscle injury. Icing (0 °C, 20 min) was carried out immediately after the injury. Heat stress (42 °C, 30 min) was applied every other day during 2-14 days after the bupivacaine injection. Injury-related increase in collagen deposition was promoted by icing. However, the level of collagen deposition in heat-stressed animals was maintained at control levels throughout the experimental period and was significantly lower than that in icing-treated animals at 15 and 28 days after bupivacaine injection. Furthermore, the recovery of muscle mass, protein content, and muscle fiber size of injured soleus toward control levels was partially facilitated by heat stress. These results suggest that, compared with icing, heat stress may be a beneficial treatment for successful muscle regeneration at least by reducing fibrosis.

Impact of heat therapy on recovery after eccentric exercise in humans

“…Our results show that exposure to HT immediately after and for 4 consecutive days after a maximal bout of eccentric exercise in humans hastens recovery of fatigue resistance and tends to reduce perceived soreness. These findings are in line with a growing body of literature supporting a beneficial impact of HT on recovery after noninjurious exercise (8) as well as severe muscle injuries (19,32,33,44,48). Additional studies are warranted to determine whether repeated exposure to local HT amplifies the skeletal muscle adaptations to exercise training in humans.…”

“…In sharp contrast to the observations of an impairment in muscle recovery following exposure to cryotherapy, mounting evidence indicates that heat therapy (HT) accelerates postexercise recovery of contractile function after endurance exercise (8) and improves muscle regeneration after severe injury (19). Indeed, studies in animal models of muscle injury induced by crushing or injection of toxins revealed that repeated exposure to HT markedly improves skeletal muscle regeneration (19,32,44,48). The beneficial effects of HT are thought to derive from several mechanisms, including accelerated infiltration of macrophages into the injury site (48).…”

Mild Hyperthermia-Induced Myogenic Differentiation in Skeletal Muscle Cells: Implications for Local Hyperthermic Therapy for Skeletal Muscle Injury

“…The increased myogenic differentiation is further supported by the enhanced fusion index and myotube sizes in a heat treatment time-dependent fashion (Figures 2(a) – 2(g) ). In previous in vivo studies using rodents, the effects of hyperthermia have been demonstrated by immersing animals with injured legs into warm water for only 20 to 30 minutes a day to avoid the excessive increase of the body temperature [ 4 , 24 , 25 ]. Therefore, it still remains elusive if a longer treatment would further enhance the rate of skeletal muscle regeneration.…”

The Role of Skeletal Muscles in Exertional Heat Stroke Pathophysiology

“…Even though microdialysis techniques exist to allow sampling of interstitial fluid in skeletal muscles [69], it is difficult to determine the source of the inflammatory cell population because during heat injury there is the infiltration of inflammatory cells into the skeletal muscle milieu [70,71]. That is where in vitro approaches can be helpful to address the problem.…”