Tsuboshima Katsuyuki, Urakawa Susumu, Takamoto Kouichi, Taguchi Toru, Matsuda Teru, Sakai Shigekazu, Mizumura Kazue, Ono Taketoshi, Nishijo Hisao
Department of System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan.
Department of Musculoskeletal Functional Research and Regeneration, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
J Appl Physiol (1985). 2020 Feb 1;128(2):296-306. doi: 10.1152/japplphysiol.00355.2019. Epub 2020 Jan 30.
Delayed-onset muscle soreness (DOMS) is a common but displeasing event induced by excessive muscle use or unaccustomed exercise and characterized by tenderness and movement-related pain in the exercised muscle. Thermal therapies, either icing or heating applied to muscles immediately after exercise, have been used as therapeutic interventions for DOMS. However, the mechanisms of their analgesic effects, and physiological and metabolic changes in the muscle during thermal therapy, remain unclear. In the present study, we investigated the effects of both thermal treatments on mechanical hyperalgesia of DOMS and physiological and muscle metabolite changes using the rat DOMS model induced by lengthening contraction (LC) to the gastrocnemius muscle. Heating treatment just after LC induced analgesic effects, while rats with icing treatment showed mechanical hyperalgesia similar to that of the LC group. Furthermore, increased physiological responses (e.g., muscle temperature and blood flow) following the LC were significantly kept high only in the rats with heating treatment. In addition, heating treatment increased metabolites involved in the improvement of blood flow and oxidative metabolisms in the exercised muscle. The results indicated that heating treatment just after LC has analgesic effects on DOMS, which might be mediated partly through the improvement of muscle oxidative metabolisms by changes in metabolites and elevated physiological responses. Physiological effects of thermal therapy in the muscle and its mechanisms of analgesic effects remain unclear. The results indicated that heating, but not icing, treatment just after lengthening contractions induced analgesic effects in the rat muscle. Increases in hemodynamics, muscle temperature, and metabolites such as nicotinamide were more prominent in heating treatment, consistent with improvement of muscle oxidative metabolisms, which might reduce chemical factors to induce mechanical hyperalgesia.
延迟性肌肉酸痛（DOMS）是一种由过度肌肉使用或不习惯的运动引起的常见但令人不适的情况，其特征是运动肌肉出现压痛和与运动相关的疼痛。热疗法，即在运动后立即对肌肉进行冰敷或热敷，已被用作DOMS的治疗干预措施。然而，其镇痛作用机制以及热疗期间肌肉的生理和代谢变化仍不清楚。在本研究中，我们使用对腓肠肌进行拉长收缩（LC）诱导的大鼠DOMS模型，研究了两种热疗对DOMS机械性痛觉过敏以及生理和肌肉代谢物变化的影响。LC后立即进行热敷治疗可产生镇痛作用，而冰敷治疗的大鼠表现出与LC组相似的机械性痛觉过敏。此外，LC后增加的生理反应（如肌肉温度和血流量）仅在热敷治疗的大鼠中显著保持较高水平。此外，热敷治疗增加了运动肌肉中参与改善血流和氧化代谢的代谢物。结果表明，LC后立即进行热敷治疗对DOMS有镇痛作用，这可能部分是通过代谢物变化和生理反应升高改善肌肉氧化代谢来介导的。热疗在肌肉中的生理作用及其镇痛作用机制仍不清楚。结果表明，在拉长收缩后立即进行热敷而非冰敷治疗可在大鼠肌肉中产生镇痛作用。在热敷治疗中，血流动力学、肌肉温度和烟酰胺等代谢物的增加更为显著，这与肌肉氧化代谢的改善一致，这可能会减少诱导机械性痛觉过敏的化学因素。
