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[Year]
1
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Effects of Exercise Training with a Sauna Suit on Cardiovascular
Health: a Proof-of-Concept Study
Samuel S. Van de Velde1, Isaiah A. St. Pierre1, Bryant R. Byrd1, Jennifer S. Fargo1, Lexie B. Loring1, Lance C. Dalleck1
1High Altitude Exercise Physiology Program, Western State Colorado University, Gunnison, CO, USA
Abstract
Introduction: Cardiovascular disease (CVD) is the leading cause of death worldwide, accounting for
17.3 million deaths per annum, a figure that is projected to grow to more than 23.6 million by 2030. It
has been estimated that 80% of premature heart disease can be prevented through positive
modification of CVD risk factors. It has been demonstrated that systemic thermal therapy by regular
administration of heat through a variety of methodologies, such as sauna or taking a warm bath, can
induce a number of advantageous responses in terms of cardiovascular health. However, no studies
have investigated the effects of exercise training with a sauna suit, a practical and portable alternative
to other thermal treatments, on cardiometabolic risk factors. The purpose of this study was to
determine the effectiveness of exercise training with a sauna suit at positively modifying
cardiometabolic risk factors. Methods: Twelve men (mean ± SD: age, height, weight, percentage body
fat, and VO2max = 25.3 ± 7.3 yr, 179.6 ± 5.7 cm, 78.6 ± 7.6 kg, 14.6 ± 3.3 %, and 50.4 ± 8.8 mL/kg/min,
respectively) completed a 6wk exercise training program (30min sessions performed 5 days/wk at a
moderate-intensity of 55-60% heart rate reserve) while wearing a sauna suit. Cardiometabolic risk
factors were measured at baseline and post-program. Results: After 6wk of exercise training with a
sauna suit there were significant (p < 0.05) improvements in the following cardiometabolic risk factors:
percentage body fat (relative Δ -1.5%), systolic (relative Δ -1.4%) and diastolic (relative Δ -3.1%) blood
pressure, triglycerides (relative Δ -15.5%), HDL cholesterol (relative Δ +6.4%), and maximal oxygen
uptake (relative Δ +8.5%). Conclusions: Findings from the present study support the feasibility of
exercise training with a sauna suit to improve cardiovascular health. Indeed, the present study
demonstrated that regular moderate-intensity exercise training with a sauna suit elicited
improvements in cardiorespiratory fitness and positive modification to several key CVD risk factors.
Key Words: Heart Disease, Hyperthermic Conditioning, Physical Activity, Prevention
[Year]
2
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Introduction
Cardiovascular disease (CVD) is the leading
cause of death worldwide, accounting for
17.3 million deaths per annum, a figure that
is projected to grow to more than 23.6
million by 20301. It has been estimated that
80% of premature heart disease can be
prevented through positive modification of
CVD risk factors2. In particular, regular
physical activity has been shown to confer a
myriad of health benefits, including the
prevention of numerous CVD risk factors
such as hypertension, obesity, Type 2
diabetes, and dyslipidemia3. Moreover,
contemporary evidence has demonstrated
that systemic thermal therapy by regular
administration of heat through a variety of
methodologies (e.g., sauna and hot tub) can
also induce a number of advantageous
responses in terms of cardiovascular health.
Indeed, chronic exposure to heat stress (in
the form of sauna bathing) has been
reported to be associated with a reduced
risk of cardiovascular disease and mortality
from all-causes4. Additionally, Krause and
colleagues (2015) reported that
heat therapy reduces fasting glycemia,
glycated hemoglobin, body weight, and
adiposity5.
There is also evidence that exercise in
conjunction with heat therapy provides
cardiovascular health benefits. For instance,
it has been demonstrated that 3 weeks of
post-exercise sauna bathing elicits an
improvement in cardiorespiratory fitness,
most likely due to an increase in plasma
volume6. However, to our knowledge, no
studies have investigated the effects of
exercise training with a sauna suit on
cardiometabolic risk factors. It is plausible
that exercise training with a sauna suit may
provide fitness enthusiasts with a more
practical and portable heat therapy
alternative when compared to other
thermal treatments. The purpose of this
‘proof-of-concept’ study was to determine
the potential effectiveness of exercise
training with a sauna suit at positively
modifying cardiometabolic risk factors. It
was hypothesized that exercise training
with a sauna suit would elicit improvements
in cardiovascular health.
Methods
Participants
12 healthy and physically active young-to-
middle age adults (18 to 44 years of age)
consented to participate in the study.
Participants were eligible for inclusion into
the study if they were low risk and
physically active as defined by the American
College of Sports Medicine7. This study was
approved by the Human Research
Committee at Western State Colorado
University.
Experimental Design
At baseline and post-program,
measurements were obtained for all
primary outcome variables presented in
Figure 1. All baseline and post-program
measurements were obtained from each
participant at similar times of the day (± 2
hrs).
[Year]
3
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
All participants completed a standardized
6wk exercise training program that
consisted of 30min of exercise performed
on a cycle ergometer at moderate-intensity
(55-60% heart rate reserve – HRR) for 5
days/wk. All exercise sessions were directly
supervised, completed while wearing a
sauna suit (Kutting Weight, LLC., Los
Angeles, CA), and performed in controlled
environmental conditions (19°C). The
intervention was based on pilot testing
from four experimental trials: (1) 30
minutes of moderate-intensity exercise (55-
60% HRR) with a sauna suit, (2) 20 minutes
of vigorous-intensity exercise (75-80% HRR)
with a sauna suit, (3) 30 minutes of
moderate-intensity exercise (55-60% HRR)
without a sauna suit (i.e., control), and (4)
20 minutes vigorous-intensity exercise (75-
80% HRR) without a sauna suit (i.e.,
control). In the moderate-intensity exercise
trial condition there was a ~45% greater
excess post-exercise oxygen consumption
(EPOC) with the sauna suit (70 calories) vs.
control condition (45 calories). Likewise, in
the vigorous-intensity exercise trial
condition there was a ~20% greater EPOC
with the sauna suit (72 calories) vs. control
condition (88 calories).The 150 min/wk
exercise training with the sauna suit were
substituted for pre-existing exercise training
for each participant in a manner that
resulted in overall exercise training volume
and intensity remaining unchanged
throughout the 6wk intervention period.
This experimental design permitted
examination of the effectiveness of exercise
training with a sauna suit at positively
modifying cardiometabolic risk factors.
Participants were strictly instructed to
maintain their other exercise training and
dietary regimens.
Figure 1. Experimental design for cardiometabolic responses to exercise training with a sauna suit.
[Year]
4
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Protocols
Physical and physiological measurements
All physical measurements were obtained
using standardised guidelines7. Briefly,
participants were weighed to the nearest
0.1 kg on a medical grade scale and
measured for height to the nearest 0.5 cm
using a stadiometer. Percent body fat was
determined via hydrostatic weighing. Waist
circumference measurements were
obtained using a cloth tape measure with a
spring loaded-handle (Creative Health
Products, Ann Arbor, MI). A horizontal
measurement was taken at the narrowest
point of the torso (below the xiphoid
process and above the umbilicus). These
measurements were taken until two were
within 0.5 mm of each other.
Fasting blood lipid and glucose
measurement
All fasting lipid and blood glucose analyses
were collected and performed at room
temperature. Participants’ hands were
washed with soap and rinsed thoroughly
with water, then cleaned with alcohol
swabs and allowed to dry. Skin was
punctured using lancets and a fingerstick
sample was collected into heparin-coated
40 l capillary tube. Blood was allowed to
flow freely from the fingerstick into the
capillary tube without milking of the finger.
Samples were then dispensed immediately
onto commercially available test cassettes
for analysis in a Cholestech LDX System
(Alere Inc., Waltham, MA) according to
strict standardized operating procedures.
The LDX Cholestech measured total
cholesterol, high density lipoprotein (HDL)
cholesterol, low density lipoprotein (LDL)
cholesterol, triglycerides, and blood glucose
in fingerstick blood. A daily optics check
was performed on the LDX Cholestech
analyzer used for the study.
Resting heart rate and blood pressure
measurements
The procedures for assessment of resting
HR and blood pressure outlined elsewhere
were followed7. Briefly, participants were
seated quietly for 5 minutes in a chair with
a back support with feet on the floor and
arm supported at heart level. Resting HR
was obtained by palpating the radial artery
for pulse for 60 seconds. The left arm
brachial artery blood pressure was
measured using a sphygmomanometer in
duplicate and separated by 1 minute. The
mean of the two measurements was
reported for baseline and post-program
values.
Maximal exercise test
Participants completed incremental
maximal exercise on a cycle ergometer
(Viasprint 150P; Sensormedics Corp., Palm
Springs, CA) at baseline and post-program
during which gas exchange data, power
output, and HR were assessed. Participants
completed 2 minutes of pedaling at 50
Watts as a warm up. Workload was then
increased in a steplike manner equal to 8-
12 Watts/20 seconds to elicit volitional
fatigue in approximately 10-12 minutes. The
[Year]
5
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
specific workload increment for each test
was matched to participant fitness level.
Pedal cadence was maintained at 70-90
rev/min, with volitional fatigue representing
a failure to sustain pedal cadence greater
than 40 rev/min. Workload at volitional
fatigue was recorded as peak power output.
Gas exchange and data analysis
Prior to each maximal exercise test, the
metabolic cart (TrueOne 2400, Parvo
Medics, Sandy, UT) was calibrated with
gases of known concentrations (16.02% O2,
4.00% CO2) and with room air (20.93% O2
and 0.03% CO2) as per the manufacture
guidelines. Calibration of the
pneumotachometer was done via a 3 Litre
calibration syringe (Hans-Rudolph, Kansas
City, MO). Throughout the maximal exercise
test continuous pulmonary gas exchange
data was obtained. In order to determine
VO2max from the maximal exercise test, the
final 15 seconds of data were averaged
constituting the final data point. The next
closest data point was calculated by
averaging the data during the 15 seconds
prior to the final 15 seconds. The VO2max
was represented by the mean of the 2
processed data points provided a plateau
was exhibited (VO2 < 150 mL/min)8.
Determination of both the first ventilatory
threshold (VT1) and second ventilatory
threshold (VT2) were made by visual
inspection of graphs of time plotted against
each relevant respiratory variable
(according to 15 second time-averaging)9.
The criteria for VT1 was an increase in
VE/VO2 with no concurrent increase in
VE/VCO2 and departure from the linearity
of VE. The criteria for VT2 was a
simultaneous increase in both VE/VO2 and
VE/VCO2. Overall ventilatory threshold was
recorded as the mean of VT1 and VT2. All
assessments were done by two experienced
exercise physiologists. In the event of
conflicting results, the original assessments
were reevaluated and collectively a
consensus was agreed upon.
Statistical analyses
All analyses were performed using SPSS
Version 22.0 (Chicago, IL) and GraphPad
Prism 6.0. (San Diego, CA). Measures of
centrality and spread are presented as
mean SD and percentage (%) change from
baseline to post-program. Primary outcome
measures were the change in
cardiometabolic risk factors, including
VO2max, systolic blood pressure, diastolic
blood pressure, weight, waist
circumference, body composition, blood
lipids, and blood glucose. Paired t-tests
were used to compare the mean
cardiometabolic risk factors values between
baseline and post-program. The probability
of making a Type I error was set at p ≤ .05
for all statistical analyses.
[Year]
6
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Results
The intervention was well tolerated for all
12 participants. Each of the 12 participants
completed all 30 scheduled exercise
training sessions. Moreover, across 360
total exercise sessions spanning a total of
180 hours training in the sauna suit, there
were no adverse events experienced across
all exercise training sessions and all
physiological responses remained within
normal ranges.
Cardiometabolic outcomes
The physical and cardiometabolic
characteristics for participants at baseline
and 6 weeks post-training are shown in
Table 1. After 6wk, there were significant
improvements (p < 0.05) in resting heart
rate, resting systolic and diastolic blood
pressure, body composition, HDL
cholesterol, and triglycerides. In contrast,
body weight, waist circumference, total
cholesterol, LDL cholesterol, and blood
glucose were relatively unchanged (p >
0.05) following 6wk of exercise training.
Maximal exercise test outcomes
The maximal exercise test outcomes for
participants at baseline and 6wk post-
training are shown in Table 2. After 6wk,
there were significant improvements
(p < 0.05) in peak power output, ventilatory
threshold, and VO2max.
Table 1. Physical and cardiometabolic characteristics at baseline and 6wk. (Values are mean SD).
Characteristic
Baseline
6wk
relative % change
Age (yr)
25.3 7.3
____
____
Height (cm)
179.6 5.7
____
____
Body weight (kg)
78.6 7.6
78.2 7.0
-0.5%
Waist circumference (cm)
81.4 5.7
80.8 5.6
-0.7%
Body fat (%)
14.6 3.3
13.1 2.9*
-10.3%
Resting HR (b/min)
60.6 9.2
57.4 9.3*
-5.3%
Systolic blood pressure (mmHg)
118.8 3.0
117.1 2.6*
-1.4%
Diastolic blood pressure (mmHg)
79.7 4.8
77.2 5.0*
-3.1%
Total cholesterol (mg/dL)
177.0 19.2
171.3 14.1
-3.2%
HDL cholesterol (mg/dL)
54.8 14.3
58.3 11.9*
+6.4%
LDL cholesterol (mg/dL)
96.7 18.0
94.5 16.8
-2.3%
Triglycerides (mg/dL)
106.3 58.1
89.8 52.4*
-15.5%
Blood Glucose (mg/dL)
84.3 6.0
83.0 6.4
-1.5%
* Within-group change is significantly different from baseline, p < 0.05.
[Year]
7
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Table 2. Performance variables at baseline and 6wk. (Values are mean SD).
Variable
Baseline
6wk
relative % change
Peak power output (Watts)
357.8 66.6
371.3 66.3*
+3.8%
Ventilatory threshold (%)
66.9 7.7
72.5 7.1*
+8.4%
VO2max (mL/kg/min)
50.4 8.8
54.7 8.3*
+8.5%
* Within-group change is significantly different from baseline, p < 0.05.
Discussion
The primary finding of the present study is
that a short-term training program
consisting of moderate-intensity exercise in
conjunction with thermal treatment (i.e.,
wearing a sauna suit) augmented
cardiovascular health. Indeed, classical CVD
risk factors, including body composition,
HDL cholesterol, and triglycerides were all
significantly improved post-intervention.
Moreover, cardiorespiratory fitness, an
independent and powerful predictor of CVD
risk and premature mortality, was also
increased. Although administration of heat
through a variety of methodologies,
including sauna and hot tub, has been
previously demonstrated to enhance
cardiovascular health, to our knowledge,
the physiological responses to exercise
training with a sauna suit has not been
scientifically explored. As such, the results
of this novel ‘proof-of-concept’ study are
encouraging and support use of a practical
and portable sauna suit as a form of
thermal treatment to enhance exercise-
related health outcomes and prevent CVD.
Cardiorespiratory response to exercise
training with a sauna suit
We found that 6wk of moderate-intensity
exercise training with a sauna suit increased
VO2max by an absolute amount of 4.3
mL/kg/min. In terms of metabolic
equivalents (METs) this equates to ~1.2
METs (3.5 mL/kg/min = 1.0 METs). This
magnitude improvement in VO2max is
comparable to that reported elsewhere in
the literature for more high-intensity
interval training (HIT). For example,
Helgerud and colleagues reported a 4.9
mL/kg/min increase in VO2max in a cohort
of moderately trained men following 8
weeks of HIT consisting of 4 x 4 minutes of
running at 90-95% maximal HR10. In the
past decade being aerobically or physically
“unfit” has garnered considerable attention
as an independent and powerful predictor
of an increased CVD risk and premature
mortality11. For example, a meta-analysis by
Williams12 showed that there was an 40%
increase in relative risk for CVD in adults in
the lowest quartile of aerobic fitness when
compared to the highest quartile, while
more recently Blair13 proposed that a low
level of aerobic fitness accounted for more
overall deaths compared to those
attributable to traditional CVD risk factors,
such as obesity, smoking, hypertension,
high cholesterol, and diabetes. Accordingly,
the results from this current study have
novel public health relevance, as a large
number of adults fall into defined low
[Year]
8
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
aerobic fitness categories14. Overall, the
improvement in VO2max (i.e., 1.2 METs) in
the present study likely has potentially
important long-term prevention
implications as a recent work has reported
that a 1 MET increase in VO2max was
associated with an 18% reduction in CVD-
related mortality15.
Cardiometabolic responses to exercise
training with a sauna suit
The blood lipid changes in the present study
are also comparable with those typically
reported in the literature following aerobic-
based exercise training. For instance, in a
review on the lipid and lipoprotein
adaptations to exercise, Durstine et al.
(2001) reported that 15 to 20 miles per
week of brisk walking or jogging was
associated with an average 2 to 3 mg/dL
increase in HDL cholesterol and 8 to 20
mg/dL decrease in triglycerides16. Our
findings of a 3.5 mg/dL improvement in HDL
cholesterol and 16.5 mg/dL reduction in
triglycerides are in close agreement with
those previously reported. Moreover, low
HDL cholesterol values represent a strong
modifiable and independent risk factor for
CVD17. Indeed, it has been estimated that
for every 1 mg/dL increase in HDL
cholesterol, the risk for a coronary heart
disease (CHD) event is reduced by 2% in
men18. Our data therefore suggests men
reduced their risk for a CHD event by ~7%
with substitution of 150 minutes per week
of exercise with a sauna suit to their overall
training regimen.
In a previous meta-analysis19, it was
reported that aerobic exercise training will
elicit average reductions in resting systolic
and diastolic blood pressure of 3 to 4 mmHg
and 2 to 3 mmHg, respectively. The
decreased resting systolic blood pressure (-
1.7 mmHg) and diastolic blood preeure (-2.5
mmHg) measurements observed in the
present study are consistent in magnitude
with those previously reported in the
literature. Next to low cardiorespiratory
fitness, hypertension has been implicated in
the second highest number of overall
deaths according to one study13. Although
the reductions in systolic and diastolic
blood pressure in the present study appear
rather modest in nature, the reality is these
training adaptations represent a positive
impact on overall CVD risk as it has been
demonstrated that blood pressure
decreases of as little as 2 mmHg are
associated with a 6% decrease in stroke
mortality and a 4% decrease in coronary
artery disease20.
Heat treatment and cardiovascular health:
possible mechanisms
The array of cardiovascular health benefits
elicited by exercise training with a sauna
suit are likely underpinned by a number of
plausible mechanisms. For example, it has
been demonstrated that heat therapy leads
to elevations in nitric oxide – a potent
vasodilator5. Ultimately, increased
concentrations in nitric oxide can lead to
improvements in insulin signaling, body
composition, and inflammation5.
[Year]
9
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
Additionally, increased plasma volume is a
hallmark adaptation to chronic heat
exposure6. In turn, it is well known that
increased plasma volume is an important
factor mediating improvements in VO2max.
Methodological Considerations
Possible limitations to the present study
merit discussion. First, the present study did
not include a control group. Therefore, it
cannot be entirely excluded that similar
results could be achieved with an exercise
alone intervention of equal 6wk duration.
Nevertheless, the fact that the 150 min/wk
of exercise training with the sauna suit were
substituted for pre-existing exercise training
for each participant in a manner that
resulted in overall exercise training volume
and intensity remaining unchanged
throughout the 6wk intervention
strengthens the likelihood that it was
specifically exercise training with a sauna
suit that elicited positive modifications in
cardiorespiratory fitness and
cardiometabolic risk factors. Additionally,
the chronic physiological responses to
exercise training with a sauna suit may be
more pronounced with a longer training
period beyond the 6wk duration of the
present study.
Conclusions
The main findings of the current study
indicate that exercise training with a sauna
suit confers numerous cardiovascular health
benefits. Previous research has shown that
chronic exposure to heat stress (in the form
of sauna bathing) is linked with reduced risk
for both cardiovascular disease and
mortality from all-causes4. The favorable
changes in various cardiometabolic risk
factors (body composition, blood pressure,
and lipid profile) and cardiorespiratory
fitness observed in the present study
following exercise training with the sauna
suit provide a likely mechanistic explanation
for why chronic exposure to heat stress
improves long-term health. Overall,
exercise training completed while wearing a
sauna suit provides individuals with a
practical and safe heat treatment
alternative to achieve important health and
fitness goals.
Practical Application
To our knowledge, this ‘proof-of-
concept’ study is the first to investigate
the effects of exercise training with a
sauna suit on cardiovascular health.
The present study provides preliminary
evidence that supports use of a
practical and portable sauna suit as a
form of thermal treatment to enhance
exercise-related health outcomes and
prevent CVD.
Overall, these findings are important for
exercise physiologists, fitness
professionals, and others who design
exercise programs and promote
physical activity in the adult population.
Competing interests
This investigation was supported financially by
Kutting Weight, LLC. Kutting Weight, LLC was
not involved in development of the study
design, data collection and analysis, or
[Year]
10
Van De Velde et al. (2016) Int J Res Ex Phys. 11(1):1-10.
Sponsored by:
Exercise and Sport Science Program
Western State Colorado University
preparation of the manuscript. There are no
other potential conflicts of interest related to
this article.
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