The Effect of Sauna Induced Hyperthermia on Muscle Recovery in Athlete
INTRODUCTION
Athletes are always searching for optimal performance while also trying to recover as fast as possible. As the intensity of sports and exercise ramps up, there is a greater need for recovery modalities that mitigate muscle soreness, promote healing, and allow for faster readiness for the next bout or injury. There are many recovery modalities, sauna induced hyperthermia from the sauna has attracted a lot of attention for muscle recovery. Sauna bathing, particularly. after an intense training session, is being adopted by many athletes around the world. This article will explore in detail how sauna-induced hyperthermia might support muscle recovery in athletes and what the current scientific evidence reveals.
What Is Sauna Induced Hyperthermia?
Sauna-induced hyperthermia is defined by exposure to increased ambient temperature levels (usually between 70°C and 100°C [158°F–212°F]) for about 10 to 30 minutes. Under these circumstances, one would expect core body temperature changes of approximately 1 to 2°C that subsequently elicit responses from the body. These responses include vasodilation (the widening of blood vessels, which helps dissipate heat), an increased heart rate, improvement in circulation, an increase in sweat gland activity to dissipate heat, and additional changes in blood flow. Sauna-induced hyperthermia also elicits hormonal changes in response to stressors. This response includes modifications of heat shock proteins and increased secretion of growth hormone. These adaptive responses may allow for recovery of muscles and contribute to improvements in overall athletic performance by enhancing the physical tolerance of the body to stressors.
Physiological Effects of Sauna Induced Hyperthermia in Muscle Recovery
1. Improve Blood Flow
There are many physiological changes your body experiences due to an increase in temperature and subsequent sauna exposure.
- One of the first responses to heat is vasodilation, or the dilation (widening) of blood vessels (capillaries) close to the skin, which occurs in response to high temperatures and hot sauna air. This vasodilation increases blood flow to the skin and to the peripheral musculature.
- Enhanced peripheral blood flow (perfusion) is beneficial for recovery from any strenuous physical activity as it provides excess blood flow, oxygen and essential nutrients to muscle tissues. Increased peripheral circulation or perfusion also helps the body remove metabolic waste products, such as lactic acid, that build up during heavy exercise (muscle fatigue). Increased circulation allows fatigued (and often damaged) muscle fibers to receive oxygen quicker and replace lost nutrients quicker as well.
- With fast muscle perfusion, the muscle may begin the rebuilding process of muscle repair and regeneration following an extended bout of exercise. Enhanced perfusion improves muscle recovery, increasing the rate and quality of recovery and repair after exercise.
2. Induction of Heat Shock Proteins
Heat exposure while using a sauna stimulates the production of heat shock proteins (HSPs), particularly HSP70 which is an essential component of cellular protection and recovery.
- HSPs’ function is serving to assist in proper folding of proteins and repair proteins that have experienced damage, which helps maintain both the functional structure of proteins that are damaged during vigorous physical activity.
- HSPs also have a role in protecting cells from oxidative stress by eliminating harmful free radicals and stabilizing newly synthesized muscle protein in the hours and days following exercise.
- HSPs allow cellular processes to occur that retain the integrity of muscle under stress and dramatically speed recovery that occurs after exercise.
3. Reduction in Muscle Soreness
After physical exertion, the body undergoes an inflammatory process in response to microtears in the muscle fibers often resulting in soreness and discomfort.
- Sauna bathing is one strategy to mitigate post-exercise associated inflammation by reducing the levels of pro-inflammatory cytokines (for example, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha)).
- Also, sauna bathing activates anti-inflammatory pathways to regulate and balance the immune response. This process can lead to a marked decrease in Delayed Onset Muscle Soreness (DOMS) that often follows strenuous exercising.
- Repeated sauna bathing after exercise is connected with reductions in the markers of inflammation supporting an expedited recovery pathway and better muscle health.
4. Hormonal Response
Sauna use stimulates key hormonal shifts that are associated with both recoverability and mental restoratives.
- Growth hormone (GH) is one of the hormones that respond to sauna exposure. GH is associated with muscle repair, tissue restoration, and overall adaptations to physical stressors. A post sauna spike in GH following sauna exposure can aid the body’s recoverability from strenuous exercise.
- With this dehydration response, sauna bathing also promotes the release of endorphins, which are natural brain chemicals that help reduce pain and improve mood. In addition to alleviating pain, endorphins also enhance a sense of calmness and reduction in stress, both of which further supports an individual’s recoverability.
5. Mitochondrial Biogenesis and Cellular Repair
Studies have evidenced that exposure to hyperthermia induced by sauna can aid mitochondrial biogenesis, which is the process of forming new mitochondria in muscle cells.
- The increase in mitochondrial density improves the cell’s ability to generate energy in the ATP pathway efficiently. Under intense exercise, endurance athletes depend on rapid ATP recovery and thus any method to improve the number and functionality of their mitochondria can enhance the cellular energy metabolic system and provide metabolic reparative adaptation to the cell.
- Improved performance from increased endurance and reduced recovery times results from several sessions induced by hyperthermia. Furthermore beyond cellular energy metabolism, hyperthermia induced adaptations improve cellular repair and resiliency.
Scientific Evidence on Sauna and Muscle Recovery
Many scientific studies have demonstrated the effectiveness of sauna therapy in muscle recovery and increased athletic performance.
- A study by Scoon et al. (2007) demonstrated that using a sauna in the 30 minutes after exercising (for 30 minutes) increased endurance performance in distance runners after 3 weeks of habitual use.
- Laukkanen et al. (2018) followed up with a study showing that after habitual sauna use, subjects had better vascular function and lower inflammation markers. Both vascular health and recovery with markers of inflammation are necessary for recovery. Regarding regeneration, studies show sauna use improves muscle capillarization and increases variables of mitochondrial biogenesis which is important for prolonged muscle performance and endurance.
- A 2020 review identified that localized heat therapy is effective for accelerating recovery with exercise induced muscle damage.
- Heat therapy activates heat shock proteins (HSP) which assist in muscle repair and lowers the risk of injury associated with physical activity, both of which demonstrate healing in tissues at the cellular level. Overall, sauna therapy provides recovery benefits that are supported by the current science for athletes and active lifestyles.
Final Thought
Hyperthermia via the sauna is a scientifically substantiated, holistic option for muscle recovery. Sauna therapy enhances muscle recovery, accelerates performance, and utilizes mechanisms such as increasing circulation, activating heat shock proteins, reducing inflammation, and influencing hormonal pathways and mitochondrial biogenesis. Post-exercise regular sauna therapy could help decrease soreness, facilitate tissue regeneration, and promote psychological health. As this recovery method is well-supported with literature, the sauna can be shown to help improve athletic performance while also developing long-term physical resilience. Sauna bathing as a natural and highly available recovery tool can be a viable course of action for athletes that want to maximize their performance and enhance its recovery.
Reference
- Patrick, R. P., & Johnson, T. L. (2021). Sauna use as a lifestyle practice to extend healthspan. Experimental Gerontology, 154, 111509. https://doi.org/10.1016/j.exger.2021.111509
- Huhtaniemi, I. T., & Laukkanen, J. A. (2020). Endocrine effects of sauna baths. Current Opinion in Endocrine and Metabolic Research, 11, 15-20. https://doi.org/10.1016/j.coemr.2019.12.004
- Marchant, E. D., Nelson, W. B., Hyldahl, R. D., Gifford, J. R., & Hancock, C. R. (2023). Passive heat stress induces mitochondrial adaptations in skeletal muscle. International Journal of Hyperthermia, 40(1). https://doi.org/10.1080/02656736.2023.2205066
- Scoon, G. S., Hopkins, W. G., Mayhew, S., & Cotter, J. D. (2006). Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport, 10(4), 259–262. https://doi.org/10.1016/j.jsams.2006.06.009
- Laukkanen, J. A., Laukkanen, T., & Kunutsor, S. K. (2018). Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the evidence. Mayo Clinic Proceedings, 93(8), 1111–1121. https://doi.org/10.1016/j.mayocp.2018.04.008
- Kim, K., Monroe, J. C., Gavin, T. P., & Roseguini, B. T. (2020). Local Heat Therapy to Accelerate Recovery After Exercise-Induced Muscle Damage. Exercise and Sport Sciences Reviews, 48(4), 163. https://doi.org/10.1249/JES.0000000000000230
