Dallas Chiropractor Best Practices

Research Commentary;

Benefits of Sauna and Exercise

By: Lee, E., Kolunsarka, I., Kostensalo, J., Ahtiainen, J. P., Haapala, E. A., Willeit, P., Kunutsor, S. K., & Laukkanen, J. A.

A Review by Dr. Trenton Yeomans

Benefits of Sauna and Exercise

 

Summary of The Benefits of Sauna and Exercise

As a Chiropractor, I am always interested in any study that helps me become a healthier individual by adding little things in my daily routine. This study by Lee et al, wanted to see the effects of sauna and exercise on cardiovascular fitness. In this study, sauna use for 15 minutes 3 times a week in combination with regular exercise was shown to greatly improve cardiorespiratory fitness, decrease systolic blood pressure, and total cholesterol levels when compared to a control group.

“A significant portion of the general population today has at least one cardiovascular disease (CVD) risk factor (obesity, elevated blood pressures, elevated cholesterol, family history of coronary heart disease, and smoking or a history of smoking).”

“Regular exercise using the recommended guidelines three times a week, for 50 min each time, can effectively improve CRF and body composition. The addition of a regular 15-min typical Finnish sauna after exercise supplemented the gains in CRF, reductions in SBP, and lowered total cholesterol levels considerably.”

We know exercise has many benefits and plays a pivotal role in maintaining our overall health and well-being and keep our bodies in a homeostasis state. When we move and exercise research has shown that we decrease inflammation, we stay younger, and we improve our body’s ability to fight against degeneration, disease, and sickness. In this time of prioritizing health and longevity, understanding and embracing the importance of fitness and exercise is an essential step toward a healthier and more fulfilling life. Sauna use is something I think as a cheat code to being a healthier individual. It’s something we can add on top of exercise to improve our mood, cardiovascular fitness, and decrease cardiovascular disease risk factors, so if you have access to a sauna try it out! Even if it is just 15 minutes 3 times a week you will feel the difference and be on track to being a healthier individual.

 

Methods

After the successful completion of prescreening procedures, participants were randomized into the EXS, EXE, or the CON group (Fig. 1). The randomization sequence was created using Excel 2016 (Microsoft, Redmond, WA) with a 1:1:1 allocation using simple randomization with stratification by a researcher with no clinical involvement in the trial. Biological sex was used for stratification, as there was a disproportionate number of female to male participants. Forty-eight participants (42 females, 6 males) were enrolled into the trial by the corresponding author. Participants were assigned to their respective interventions (16 per group, 14 females, and 2 males) by a member of the research team who was uninvolved with the data collection and analysis process. To ensure that the statistical analyses were nonbiased, the statistician was blinded to the assignment and completely uninvolved in the participant recruitment and data collection processes.

Participants in the CON group were informed that a similar 8-wk supervised exercise training program would be offered to them after the trial. This was done to minimize dropout rates and increase adherence to preexisting lifestyle and physical activity habits during the trial period to reduce potential confounding factors. The study consisted of two measurement days completed by all groups and an 8-wk intervention for the EXS and EXE groups. Participants recorded and submitted a food diary the day before their preintervention (PRE) measurement. This was returned to them 48 h before the postintervention (POST) measurement, and they were carefully instructed to follow the same food intake before their measurement days. All participants were reminded regularly to maintain their regular daily activities and diet to minimize the possible influence of external variables on the outcome measures.

The intervention groups exercised three times a week (Monday, Wednesday, and Friday) in the evenings, between 1600 and 2100. Training sessions were carried out in groups of 1–5 participants with two qualified instructors. A predetermined adherence rate of 95% for 24 training sessions was successfully achieved. One participant from the EXS group dropped out during the first week due to undisclosed personal reasons. The exercise intervention was based on the Finnish national exercise guidelines (31), which are adapted from the guidelines of the American College of Sports Medicine (ACSM) and reflect current recommendations (3). Each exercise session lasted 60 min and was performed in the following order: a 10-min full-body warm-up, 20 min of resistance exercise, and 30 min of aerobic exercise.

Details of the intervention. Loads were increased for resistance exercises when participants were able to complete the movement comfortably with good form. More challenging variations for the bodyweight exercises were introduced when the participant completed the basic movement with no noticeable difficulties. For example, resistance bands were used for dead bugs, bird-dog were executed with eyes closed, etc.

Resistance training was a mixture of body weight and basic resistance training exercises. Starting loads for each resistance exercise were determined individually on a separate day before the intervention. The exercises were performed in a circuit fashion, with the aim of providing a full-body workout. Each circuit consisted of five movements, and each movement was performed for 45 s with a 15-s break between them. Completion of a circuit took 5 min, followed by a 1-min break. The circuits were completed three times each session. Circuits A and B were used alternately in each training for the first 4 wk, and circuits C and D were used in the final 4 wk. Harder variations of body weight movements and greater resistance exercise loads for each individual were introduced as performance improved, based on the assessment of the exercise instructors.

Aerobic exercise was performed using Monark cycle ergometers (Monark 828 E, Varberg, Sweden). Individual maximum heart rates were calculated (32) and used thereafter to prescribe aerobic exercise intensity, starting from 65% of maximum heart rate with a fortnightly increase of 5%. Aerobic exercise heart rate was closely monitored and verified every 5 min. Participants maintained a constant pedaling frequency of 65–70 revolutions per minute (rpm), while the magnetic resistance of the bike ergometer was adjusted to achieve the required exercise intensity. After aerobic exercise, participants in the EXS group proceeded to the sauna room, whereas those in the EXE group waited in the gym until the participants in the EXS group completed 15 min of sauna exposure. The temperature of sauna exposure started from 65°C and was increased by 5°C fortnightly and was monitored and recorded every minute via a commercially available wireless thermometer unit (Wireless thermometer 7410; Suomen Lämpömittari Oy, Helsinki, Finland). Relative humidity of the sauna room was between 10% and 20%. Participants were allowed to leave the sauna at any time if they felt uncomfortable, but all participants in the EXS group completed all 15 min of every postexercise sauna exposure successfully without leaving the sauna room.

 

Results

In this multi-arm RCT, we compared the effects of an 8-wk exercise and sauna intervention (EXS) to regular exercise without sauna (EXE), using a sedentary population with relatively low physical activity levels and at least one traditional CVD risk factor. A control group (CON) was included to validate the efficacy of the exercise intervention. Our results show improvements in CRF based on the estimated V̇o2max and lower fat mass for the EXE group compared with the CON group. More importantly, the EXS group demonstrated a greater increase in CRF, and greater decreases in SBP and total cholesterol levels, when compared with the EXE group.

To a reasonable extent, the differences seen between the CON and EXE groups were expected. Physical activity guidelines supported by research evidence suggest that 150 min of moderate-intensity exercise per week is sufficient to induce beneficial health adaptations (4). As such, our 8-wk exercise intervention was constructed to adhere as closely as possible to the recommendations (31). Every supervised session included a full-body warm-up, followed by resistance, then aerobic exercise. In addition, exercise intensity was progressively increased throughout the 8 wk, for both resistance and aerobic exercise.

The long-term benefits of exercise training on physical health have been well established (3, 39), and regular aerobic training has been shown to improve both body composition (39) and CRF (40) even at relatively lower intensities, which is consistent with the main findings of the current study. Furthermore, it has been well documented that performing resistance exercise before aerobic exercise leads to higher energy expenditure and fat mass loss (41–43), which was how our training sessions were designed. The results from this experiment are in support of the literature and are indicative that the 8-wk exercise intervention provided an adequate stimulus for physiological adaptations to both CRF and body composition.

Despite these adaptations, however, there were no differences in changes to BP and other secondary variables such as arterial stiffness between the EXE and CON groups. This may have been partially due to the length of the present intervention, as training interventions are typically longer in duration. Although cardiovascular adaptations such as arterial remodeling and capillary growth have been well documented to occur within the first few weeks of exercise training (44), this did not appear to be the case. The structure of the exercise training likely contributed to this lack of response in the other variables, as the divergent nature of resistance and aerobic exercise has been reasonably established (45). Moreover, combined resistance and aerobic training have been documented to be less effective than aerobic training alone in reducing arterial stiffness (46) and BP (47).

One of the objectives of the current study was to elucidate the synergistic effects of sauna exposure and exercise on the primary variables of BP and CRF, in a sedentary population with traditional CVD risk factors. Specifically, our data suggest that the addition of 15-min sauna exposure, regularly after every exercise session, three times a week for 8 wk was able to improve CRF, SBP, and total cholesterol levels significantly, when compared with performing the same exercise intervention alone. Indeed, previous studies have shown that sauna exposure is an effective additive tool to an exercise program for both clinical (13, 48) and athletic populations (10, 49).

Studies have found positive acute cardiovascular responses from the use of passive heat (50), sauna exposure (27, 51), and sauna exposure with exercise (52, 53). A recent study also showed that postexercise sauna exposure had an augmentative effect, thereby increasing the overall training stress (54). However, to our best knowledge, this is the first multi-arm RCT investigating the cardiovascular and health effects of long-term sauna exposure in the general population with CVD risk factors. The current results suggest that the addition of regular sauna exposure was able to increase CRF and led to a decrease in SBP when comparing the EXS and EXE groups.

Heat acclimation studies have shown the efficacy of using heat to improve aerobic fitness (55, 56). Moreover, the use of heat has been shown to induce a greater level of acute physiological strain and cellular response at a lower relative workload than hypoxia (57). Therefore, it is more likely that the present cardiovascular adaptations seen in this study may be the result of functional enhancements rather than structural changes in the arteries (58), as there were no significant changes to PWV and AIx as measures of arterial stiffness. Nevertheless, this needs to be further investigated, as heat shock proteins, muscle endothelial nitric oxide synthase content, and capillary density were not measured in the present study.

It is worth noting that CRF adaptations to passive heat exposure in the form of sauna bathing have yet to be thoroughly investigated mechanistically. However, cardiovascular adaptations to heat acclimation have been well documented (59), which provides us with a vital framework that may explain the difference in CRF between the EXE and EXS groups. Exercise training and passive heat have been shown to have additive effects that lead to improved myocardial contractility, over exercise training or heat alone, in animal models (60). Eight weeks of heat acclimation has been shown to improve myocardial compliance, rendering it more efficient (60, 61). It is thus plausible that cardiovascular stability may have been augmented by the addition of regular sauna exposure to exercise, and that functional, rather than morphological adaptations were responsible for the differences in CRF between the intervention groups, particularly in the absence of changes to arterial stiffness parameters. Moreover, infrared sauna therapy (13) has also been shown to augment increases in CRF via functional changes, which is consistent with our present findings.

A recent systematic review showed that compared with controls, heat therapy decreased both SBP and DBP by an average of 4 mmHg (23). Based on the latest guidelines on BP (30, 35), it was postulated that a reduction in BP by ∼5 mmHg would improve individual BP categorization (23, 62). Although our study did not find differences in DBP between interventions, SBP levels for the EXS group were 8 mmHg lower than in the EXE group postintervention, which is almost an entire BP category. This is a clinically important new finding to highlight, as a recent meta-analysis (63) reported a nearly linear relationship between a 5-mmHg decrease in SBP and a lowered risk of all-cause mortality across all BP categories.

Although higher resting BP before an intervention has been suggested as a potential mitigating factor in the therapeutic effects seen in heat-related studies (23), only 35% of the participants in the current experiment had an elevated resting BP. In addition, there was no difference in the PRE values of SBP and DBP between all three groups. One mechanism that may have contributed to the lower SBP in the EXS group was the concomitant lowering of total cholesterol levels. This agrees with the findings from an earlier study (64), which found that heat therapy was able to improve the blood lipid profile, specifically total cholesterol levels, in a sedentary obese population. In addition, there were improvements to BP but no changes to BMI or body composition, which is remarkably comparable to the findings from our current study. Even though the authors used hot water immersion as opposed to the sauna, there were similarities between our experimental designs worth noting, such as the intervention period and the frequency of exposure. These are crucial factors to consider for future research in the area, as has been pointed out by several others (23, 58).

Some limitations of this study ought to be noted. The trial lacked a sauna-only group, which would have allowed us to determine if the benefits seen could have been solely attributable to the sauna. Diet of the participants was not controlled for during the trial, which could have influenced the results. However, participants followed the same diet a day before each measurement was taken, which improves the consistency and reliability of our data. Maximal oxygen consumption was not measured directly, but the indirect method better suited the study population and added external validity. The study sample had only six male participants. However, we addressed this issue using stratified randomization and included separate tables of results.

Indeed, our study does have several strengths. We extended the findings of our earlier research in the acute setting (28, 65), with an 8-wk interventional study using a sedentary population, who were nonfrequent sauna users, to investigate the complementary effects of exercise followed by sauna exposure. Body composition was determined using dual-energy X-ray absorptiometry, while arterial stiffness and BP measurements adhered closely to established guidelines (30, 35, 36). Compliance of the intervention groups was excellent, with only 2 participants each missing a single session out of 24. All other participants completed the 24 sessions successfully with only 1 dropout for the entire study. Moreover, a statistician that was blind to the intervention assignment performed the data analysis using coded variables.

In conclusion, regular exercise using the recommended guidelines three times a week, for 50 min each time, can effectively improve CRF and body composition. The addition of a regular 15-min typical Finnish sauna after exercise supplemented the gains in CRF, reductions in SBP, and lowered total cholesterol levels considerably. Future research should adopt a more systematic approach in the study of heat exposure and seek to understand the optimal exposure durations, frequencies, modalities, and temperatures for various beneficial adaptations.

 

References

Lee, E., Kolunsarka, I., Kostensalo, J., Ahtiainen, J. P., Haapala, E. A., Willeit, P., Kunutsor, S. K., & Laukkanen, J. A. (2022). Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: A multi-arm, randomized controlled trial. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 323(3). https://doi.org/10.1152/ajpregu.00076.2022

 

Our Message

We love to help our patients in East Dallas stay healthy. We are here to relieve back pain, neck pain and headaches while also teaching about how our diet and stress effects our over all health. By improving these areas of our lives we can become healthier, stay out of pain and reduce risk of diseases. Our Chiropractors located in Lakewood near, the corner of Mockingbird Ln. and Abrams Rd., will teach you what the research says about the Benefits of Sauna and Exercise want to help you stay healthy and out of pain.