This article is featured in: Research Highlights, Office of Research and Development
Original link: https://rh.acad.ntnu.edu.tw/tw/article/content/168 (2022.09.06)
(English Version Powered by ChatGPT, Edited by Serena H.)
When the general public engages in unfamiliar eccentric exercises, it often triggers delayed onset muscle soreness (DOMS), which in turn causes proprioceptive dysfunction and affects daily activities. However, far-infrared radiation is a non-invasive method that can penetrate into deep tissues of the human body; thus, recent studies suggest it may be a potential way to relieve pain and promote better healing of injured tissues. Nevertheless, the therapeutic effects of far-infrared radiation on DOMS and proprioception remain unclear.
This study aims to test the hypothesis: after performing a single bout of maximal eccentric exercise on one side’s elbow flexor muscles, would four consecutive days of far-infrared radiation be more effective than sham treatment in reducing DOMS and restoring proprioception? Women with regular physical activity were randomly assigned to either the far-infrared radiation group or the sham treatment group (9 participants per group).
Each participant performed a single session of 12 sets of 6 repeated bouts of maximal isokinetic eccentric exercise using the elbow flexors on either the left or right arm, in a balanced manner. At 1, 25, 49, and 73 hours after the eccentric exercise, the infrared group received far-infrared radiation while the sham group received blue light exposure. Measurements of DOMS, joint position sense, and angle of joint release were taken at pre-exercise, and at 0, 24, 48, 72, 96, and 120 hours post-exercise.
The results showed that when DOMS was induced by eccentric exercise, far-infrared radiation significantly outperformed the sham treatment in alleviating DOMS, which also led to faster recovery of joint position sense and joint release angle compared to the sham group. These findings indicate that far-infrared radiation treatment is clearly more effective than sham treatment in accelerating the reduction of DOMS and the recovery of proprioception after eccentric exercise, suggesting that it could serve as an effective method for the general public to relieve DOMS and recover from proprioceptive decline following eccentric activity.
People without habits of exercising regularly who suddenly engage in intense physical activities (e.g., moving house, downhill hiking, running, resistance training), especially when performing unfamiliar eccentric movements, are prone to experiencing delayed onset muscle soreness (commonly known as “iron legs” in Taiwan).
This leads to decreased muscle function and proprioceptive disruption, which in turn impacts daily life. Athletes who abruptly increase training intensity or volume also often face issues like muscle soreness, reduced performance, and impaired muscle function.
From news reports in the past, there have been frequent complaints from parents alleging that students were subjected to physical punishment by teachers (e.g., frog jumps, running stairs) or by military superiors (e.g., unreasonable drills with no access to hydration), resulting in “iron legs,” muscle inflammation (myositis), or rhabdomyolysis — all posing serious health risks.
Although the negative symptoms caused by eccentric exercise typically last about 5 to 14 days, current literature shows that with proper management — such as drinking at least 1.5 liters of water per day and using cooling methods — these conditions are not life-threatening.
However, how to get rid of muscle soreness, maximize athletic performance, and restore from the decrease in muscle performance and proprioception, has long been an issue frequently faced by the public and athletes alike, requiring effective solutions.
Therefore, developing effective and easy-to-apply methods to reduce fatigue, restore performance, and improve proprioceptive recovery has been one of the long-term goals set by sports scientists.
Far-infrared radiation is a non-invasive treatment that can penetrate into the deep tissues of the human body, and recent animal studies have shown that it can relieve long-term chronic muscle pain, improve blood circulation at the targeted area, enhance healing and recovery of injured tissues, and also reduce high blood pressure and inhibit neural tissue overgrowth.
Yet, the effects of far-infrared radiation in relieving or accelerating recovery from muscle soreness and fatigue or proprioceptive disorders caused by eccentric exercise have not been studied in prior literature. Therefore, this study was conducted to investigate these specific issues.
The results revealed that when eccentric exercise caused significant muscle soreness and proprioceptive disturbance, administering 30 minutes of far-infrared radiation per day for four consecutive days not only significantly improved soreness relief compared to the sham treatment, but also made the recovery of proprioceptive function faster than in the sham group.
These findings suggest that far-infrared radiation treatment is clearly more effective than sham treatment in accelerating both the relief of muscle soreness and the recovery of proprioceptive function after eccentric exercise. Therefore, far-infrared radiation could serve as an effective method for the general public to reduce muscle soreness, alleviate fatigue, and aid recovery from proprioceptive disturbance caused by intense physical activity.
Original Source: Chou, T.-Y., et al. (2020). Evaluation of the Effects of Far-Infrared Radiation on Delayed Onset Muscle Soreness and Proprioception Recovery. Physical Education Journal, 53(2), 235–249.
https://doi.org/10.6222/pej.202006_53(2).0007
https://doi.org/10.6222/pej.202006_53(2).0007