International Journal of Physical
Medicine & Rehabilitation

Mini Review

Enhanced Athletic Recovery Using Cold-Water Immersion with Dissolved CO2
and H2
Miho Yoshimura1*, Yoshiyuki Fukuoka1, Yuri Sawada2, Hiroshi Ichikawa2, Masatoshi Nakamura3
1Department of Health and Sports Science, Doshisha University, Tatara Miyakodani, Kyotanabe, Kyoto, Japan; 2Department of Life

and Medical Science, Doshisha University, Tatara Miyakodani, Kyotanabe, Kyoto, Japan; 3Department of Rehabilitation Sciences,
NishiKyushu University, Kanzaki, Saga, Japan

ABSTRACT
A Cold therapy is widely recognized as a prescription for acute-phase recovery in athletes. However, it has beensuggested that vasoconstriction caused by cooling may, in fact, delay the recovery process after exercise. Therefore, weare researching a new cooling method that involves supplementing ice baths with carbon dioxide gas, which has
vasodilatory effects, and hydrogen gas, which has anti-inflammatory properties. This new approach aims to improvemuscle blood flow and performance while maintaining the benefits of cooling, such as pain alleviation. This mini
review provides an overview of the acute recovery effects of this innovative method and its potential applications.
Keywords: Cold-water immersion; Carbon dioxide; Hydrogen; Muscle damage; Recovery; Athlete

INTRODUCTION
Cold-water immersion after exercise has become a common
practice on the competitive sports scene. Athletes engage in daily
training to enhance their performance and may participate inmultiple competitions a day, sometimes consecutively. Therefore,
discovering a body conditioning strategy for the period of amatch (e.g. in sports) and the most effective recovery regimen is
crucial for improving performance and preventing fatigue-related
injury. Cooling is one of the most widely utilized acute-phasetreatments [1-3]. In particular, Cold-Water Immersion (CWI)
after exercise has been reported to decrease muscle damage
markers such as creatine kinase and to reduce muscle fatigue andmuscle soreness [4-6]. However, recent studies have indicatedthat the cooling stimulus induces vasoconstriction, thereby
decreasing blood flow and delaying the recovery of injured
tissues [7]. Given this paradox, we have pursued innovative
recovery methods that facilitate patent blood flow while taking
advantage of the anti-inflammatory and analgesic effects ofcooling. The purpose of the present work is to review thephysiological effects of external exposure to dissolved carbon
dioxide (CO2) gas and the combination of dissolved CO2 andhydrogen (H2) gas on exercise performance in healthy subjects.
This mini-review is based on our previous literature to identify

potential athletic performance recovery and the possibility of
future research.

LITERATURE REVIEW
Cold-Water Immersion (CWI)
Clinicians CWI is a kind of cryotherapy in which the wholebody is immersed in cold water, and it has become widely
popular. However, when it comes to the effects of CWI on
performance recovery, both positive and negative observations
have been reported, and no consensus has been reached [8-10].
In a 2020 meta-analysis of male athletes, CWI following
resistance exercise sessions attenuated improvements in muscularstrength [11]. Another study suggested that the cooling stimulus
provided by CWI may induce vasoconstriction, thus reducing
blood flow [7]. Previous studies focused on the kinetics of lactate
clearance from the bloodstream have highlighted a notable
relationship between blood flow and lactate removal [12,13]. The
cooling stimulus from CWI leads to vasoconstriction, which may
potentially delay the arrival of recovery mediators and inhibit theremoval of lactate and other inflammatory substances byreducing blood flow. Although there is no consensus on the
short-and long-term effects of CWI, it is apparent that effective

Correspondence to: Miho Yoshimura, Department of Health and Sports Science, Doshisha University, Tatara Miyakodani, Kyotanabe, Kyoto, Japan; Email: mpckt.121@gmail.com
Received: 08-Nov-2023, Manuscript No. JPMR-23-27952; Editor assigned: 10-Nov-2023, Pre QC No. JPMR-23-27952 (PQ); Reviewed: 28-Nov-2023, QC
No. JPMR-23-27952; Revised: 06-Dec-2023, Manuscript No. JPMR-23-27952 (R); Published: 14-Dec-2023, DOI: 10.35248/2329-9096.23.11.704
Citation: Yoshimura M, Fukuoka Y, Sawada Y, Ichikawa H, Nakamura M (2023) Enhanced Athletic Recovery Using Cold-Water Immersion with Dissolved
CO2 and H2. Int J Phys Med Rehabil. 11:704.
Copyright: © 2023 Yoshimura M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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CWI treatment for injured muscles must address the issue of
reduced blood flow.

Carbon dioxide vasodilation
External exposure to dissolved CO2 into water is used as a typeof thermotherapy, with reported effects such as peripheral
vasodilatation, increased blood flow, and heat retention [14,15].
Hartmann reported that approximately 3% of CO2 isphysiologically released through the skin. However, when theCO2 concentration saturates the environment around the body,
CO2 absorption also takes place through the skin, both in its
gaseous form and via water containing carbonic acid [16]. Uponskin absorption or permeation, CO2 gas generates hydrogenions through buffering. These ions act upon the smooth musclesof cutaneous blood vessels, particularly the small arteries of theanterior capillaries, inducing relaxation of the vascular smoothmuscles. This relaxation causes dilation of the vessels andconsequent elevation in cutaneous blood flow [17,18].
Furthermore, there is an indication that the blood flowenhancing effect of carbonated spring water not only impacts
surface tissues but also extends to muscles [19].

Vasodilation during cooling
There have been few prior studies concerning recovery involving
the combination of cold water and CO2 gas. To confirm
whether the vasodilatory effects of CO2 gas could be activatedin the context of cold-water immersion, we conducted afoundational study. We prepared both CWI and CWI with
CO2 concentrations above 1000 ppm (C-CWI) at 20°C andassessed the changes in physiological parameters and tissue
oxygenation dynamics when one leg was immersed up to theknee [20]. Our investigation demonstrated that in C-CWI, there
was a greater increase in arterial blood flow compared to CWI.
In addition, during the 18-minute recovery period after
immersion, we observed that heat dissipation was significantly
accelerated [20]. Subsequent research involving post-bicycle
exercise performance measurements confirmed that C-CWI
significantly reduced deep body temperature and accelerated
lactate clearance [21]. When evaluated from the perspective ofathletic performance recovery, we observed a strong correlation
between acceleration of lactate clearance after water immersion
and cycling efficiency or the decrease in peak pedal repetitionsof cycling [20,21]. These observations in our previous studies
underlined the effectiveness of recovery by immersion in coldcarbonated water [21,22].

noted that even though H2 soaking does not affecttheinflammatory response, pain levels in DOMS may be
alleviated by H2 soaking.
Our recent research suggests the potential for alleviating several
symptoms of DOMS, which typically occur 48-72 hours after
eccentric exercise, by implementing a combination of dissolved
CO2 and H2 gas in Cold Water Immersion (CH-CWI) [26].
Specifically, within the CH-CWI group, there were no
significant decreases in measures such as maximal voluntaryisometric contraction torque, countermovement jump height,
and knee flexion range of motion while the other groups(Control, CWI, and C-CWI) showed significant decreases inthese variables. Additionally, echo intensity and tissue hardness
showed no significant increases in the CH-CWI group [26].
However, it is not clear how H2 gas in CH-CWI promotes
scavenging of Reactive Oxygen Species (ROS) and suppresses
inflammation and muscle damage.

DISCUSSION
Here, we present reference data for the outcomes of the CWI
with CO2 gas and H2 gas. Twenty trained male athletes (age 20.6
± 1.2 years, height 173.1 ± 5.1 cm, weight 69.9 ± 7.0 kg; means ±Standard Deviations (SDs)) were randomized into four groups(① Control, ② CWI, ③ C-CWI, and ④ CH-CWI). In thethree CWI groups, all participants were immersed in one of thethree baths at 20ºC for 20 min immediately after the first highintensity Wingate Anaerobic Test (WAnT). After the recovery
intervention, the participants performed the second WAnT
(Figure 1). Their heart rate, core body temperature, blood lactate,
and ROS including Hydroxyl radicals (･OH) were measured fourtimes at Basal Rest (BL), the end of First WAnT (WAnT①),
recovery Intervention (WI20) and the end of Second WAnT
(WAnT②). The mean power output of WAnT was also measured
at the first bout and the second bout following each recovery
intervention. The Electron Spin Resonance (ESR) spin-trapping
method is able to detect ROS and evaluate ･OH elimination
activities using the Multiple Free-Radical Scavenging (MULTIS)
method. As a result, a significant correlation between the rate ofincrease in mean power of WAnT from the 1st bout to the 2nd
bout and the rate of increase in the ･OH scavenging activity wasobserved only in the CH-CWI group (n=5, r=0.89, p<0.05)(Figure 2).

Antioxidant action of hydrogen
Exposure to dissolved Hydrogen molecular (H2) gas immediately
after high-intensity exercise has also been tried as a strategy for
decreasing inflammation and muscle injury [23]. H2 can beabsorbed by the body through a variety of routes, including
drinking and soaking. H2 is thought to selectively neutralizehydroxyl radicals and peroxynitrite in cells and exhibit
cytoprotective effects against oxidative stress [24]. For instance,
Kawamura evaluated the pain associated with Delayed Onset
Muscle Soreness (DOMS) using a visual analog scale [25]. TheyInt J Phys Med Rehabil, Vol.11 Iss.11 No:1000704

Figure 1: Experimental protocol. Note: Participants were asked
to rest for 15 minutes and then pedal for 10 minutes to warm
up. Next, they underwent a 30 seconds WAnT. After the
exercise, participants had a 20 minutes recovery period with
passive recovery (Control), CWI, C-CWI or CH-CWI.
Following the interventions, the participants performed theexercise again.

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FUNDING
This study was supported by an Osaka City Innovation
Creation Support Grant (2019).

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Figure 2: Relationship between ･OH scavenging activity andmean power. Note: A significant correlation between theincrease rate in mean power of WAnT ((WAnT②-WAnT①)/
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Moreover, by adding H2 gas to the C-CWI, there was anindication of the potential to alleviate some symptoms of DOMS
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Further analysis is required to understand the mechanism ofinteraction between CO2 gas and H2 gas.

ETHICS STATEMENT
This study was approved by the Ethics Committee of theInstitutional Review Board of the Doshisha University, Kyoto,
Japan (no.19023), and complied with the requirements of the
Declaration of Helsinki.

CONFLICTS OF INTEREST
The authors have no conflicts of interest relevant to this article.
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CONCLUSION
We investigated whether the new CWI method, which involves
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