Icing after skeletal muscle injury decreases M1 macrophage accumulation and TNF-α expression during the early phase of muscle regeneration in rats

Effects of thermal interventions on skeletal muscle adaptations and regeneration: perspectives on epigenetics: a narrative review

Recovery methods, such as thermal interventions, have been developed to promote optimal recovery and maximize long-term training adaptations. However, the beneficial effects of these recovery strategies remain a source of controversy. This narrative review aims to provide a detailed understanding of how cold and heat interventions impact long-term training adaptations. Emphasis is placed on skeletal muscle adaptations, particularly the involvement of signaling pathways regulating protein turnover, ribosome and mitochondrial biogenesis, as well as the critical role of satellite cells in promoting myofiber regeneration following atrophy. The current literature suggests that cold interventions can blunt molecular adaptations (e.g., protein synthesis and satellite cell activation) and oxi-inflammatory responses after resistance exercise, resulting in diminished exercise-induced hypertrophy and lower gains in isometric strength during training protocols. Conversely, heat interventions appear promising for mitigating skeletal muscle degradation during immobilization and atrophy. Indeed, heat treatments (e.g., passive interventions such as sauna-bathing or diathermy) can enhance protein turnover and improve the maintenance of muscle mass in atrophic conditions, although their effects on uninjured skeletal muscles in both humans and rodents remain controversial. Nonetheless, heat treatment may serve as an important tool for attenuating atrophy and preserving mitochondrial function in immobilized or injured athletes. Finally, the potential interplay between exercise, thermal interventions and epigenetics is discussed. Future studies must be encouraged to clarify how repeated thermal interventions (heat and cold) affect long-term exercise training adaptations and to determine the optimal modalities (i.e., method of application, temperature, duration, relative humidity, and timing).

Cryotherapy for treating soft tissue injuries in sport medicine: a critical review

Sports medicine physicians and physiotherapists commonly use cryotherapy (eg, ice application) postinjury to decrease tissue temperature with the objective of reducing pain, limiting secondary injury and inflammation, and supporting healing. However, besides the analgesic effect of cryotherapy, a literature search revealed no evidence from human studies that cryotherapy limits secondary injury or has positive effects on tissue regeneration. Thus, our current understanding of the potential mechanisms and applications of cryotherapy largely relies on the results from animal studies. Importantly, treatment should not aim at obliterating the inflammatory and regeneration processes but instead aim to restore an adapted/normal regulation of these processes to improve function and recovery. However, some animal studies suggest that cryotherapy may delay or impair tissue regeneration. With the translation of laboratory animal studies to human sport medicine being limited by different injury and muscle characteristics, the effect of cryotherapy in patients with musculoskeletal injuries is uncertain. Thus, pending the results of human studies, cryotherapy may be recommended in the first 6 hours following an injury to reduce pain (and possibly haematoma), but it should be used with caution beyond 12 hours postinjury as animal studies suggest it may interfere with tissue healing and regeneration.

Frequent Icing Stimulates Skeletal Muscle Regeneration Following Injury With Necrosis in a Small Fraction of Myofibers in Rats

Icing interventions on the injured skeletal muscle affect the macrophage-related regenerative events and muscle repair. However, despite its importance for the practice in sport medicine, the influence of different icing protocols on muscle regeneration remains unclear. Here, using a rodent model of mild muscle injury with necrosis in a small fraction of myofibers, the injured animals were allocated to four groups: non-icing control (Con) and a single treatment (Ice-1), three treatments (Ice-3), or nine treatments (Ice-9) with a 30-min icing each time within two days following injury. Muscle regeneration was compared between the groups on post-injury days 1, 3, 5, and 7. The results showed that compared with the Con group, muscle regeneration was faster in the Ice-9 group (but not in the Ice-1 and Ice-3 groups), as indicated by more rapid accumulation of satellite cells within the regenerating area and enlarged size of regenerating myofibers (p<0.05, respectively). There was also less macrophage accumulation (p<0.05) and a trend toward early removal of necrotic myofibers in the damaged/regenerating area in the Ice-9 group (p=0.0535). These results demonstrate that in the case of mild muscle damage, more frequent icing treatment is more effective to stimulate muscle regeneration.

Resveratrol and Vitamin D: Eclectic Molecules Promoting Mitochondrial Health in Sarcopenia

Sarcopenia refers to the progressive loss and atrophy of skeletal muscle function, often associated with aging or secondary to conditions involving systemic inflammation, oxidative stress, and mitochondrial dysfunction. Recent evidence indicates that skeletal muscle function is not only influenced by physical, environmental, and genetic factors but is also significantly impacted by nutritional deficiencies. Natural compounds with antioxidant properties, such as resveratrol and vitamin D, have shown promise in preventing mitochondrial dysfunction in skeletal muscle cells. These antioxidants can slow down muscle atrophy by regulating mitochondrial functions and neuromuscular junctions. This review provides an overview of the molecular mechanisms leading to skeletal muscle atrophy and summarizes recent advances in using resveratrol and vitamin D supplementation for its prevention and treatment. Understanding these molecular mechanisms and implementing combined interventions can optimize treatment outcomes, ensure muscle function recovery, and improve the quality of life for patients.

Regulation of Satellite Cells Functions during Skeletal Muscle Regeneration: A Critical Step in Physiological and Pathological Conditions

Skeletal muscle regeneration is a complex process involving the generation of new myofibers after trauma, competitive physical activity, or disease. In this context, adult skeletal muscle stem cells, also known as satellite cells (SCs), play a crucial role in regulating muscle tissue homeostasis and activating regeneration. Alterations in their number or function have been associated with various pathological conditions. The main factors involved in the dysregulation of SCs' activity are inflammation, oxidative stress, and fibrosis. This review critically summarizes the current knowledge on the role of SCs in skeletal muscle regeneration. It examines the changes in the activity of SCs in three of the most common and severe muscle disorders: sarcopenia, muscular dystrophy, and cancer cachexia. Understanding the molecular mechanisms involved in their dysregulations is essential for improving current treatments, such as exercise, and developing personalized approaches to reactivate SCs.

Is it the End of the Ice Age?

The use of the RICE (Rest, Ice, Compression, Elevation) protocol has been the preferred method of treatment for acute musculoskeletal injuries for decades. However, the efficacy of using ice as a recovery strategy following injury in humans remains uncertain, and there is a growing trend recommending against icing following injury. Animal models suggest that while ice can help to accelerate the recovery process, extreme muscle cooling might delay repair and increase muscle scarring. Despite the conflicting evidence, ice should not be dismissed as a potential treatment option. When considering what is known about the injury cascade, the optimal application window for ice is in the immediate acute stage following injury to reduce the proliferation of secondary tissue damage that occurs in the hours after the initial injury. Practitioners should tailor the application of ice based on the injury timeline and repair process, consistent with applications in 20-30 minute intervals within the first 12 hours post-injury. Until the evidence unanimously proves otherwise, the culture of icing injuries should remain a staple in sports medicine.