Effects of artificial CO₂-rich cold-water immersion on repeated-cycling work efficiency

ABSTRACT

We investigated the acute effects of cold-water immersion (20°C) with higher CO₂ concentration (CCWI) following a high-intensity Wingate anaerobic exercise test (WAnT) on subjects’ sublingual temperature (T_sub), blood lactate ([La]b), heart rate (HR), and aerobic cycling work efficiency (WE) compared to cold tap-water immersion (20°C; CWI) and passive recovery (PAS). Fifteen subjects completed three testing sessions at 1-week intervals. Each trial consisted of a first WE and WAnT, and a 20-min recovery intervention (randomized: CCWI, CWI, and PAS) before repeating a second WE and WAnT. The WE was measured by the metabolic demand during 50% V.O₂max exercise. HR, T_sub, and [La]b were recorded throughout the testing sessions. There was a significant decline in the WE from 1st bout to 2nd bout at each recovery intervention. The WAnT was also significantly reduced at 2nd bout. Significantly reduced [La]b was achieved at CCWI compared to PAS, but not to the CWI. Likewise, the reduction in HR following immersion was the largest at CCWI compared to the other conditions. These findings indicate that CCWI is an effective intervention for maintaining repeated cycling work efficiency, which might be associated with reduced [La]b and HR.

KEYWORDS:

• Cold water
• work efficiency
• Wingate test
• lactate
• heart rate
• carbon dioxide

Acknowledgments

The authors thank all fifteen participants, who volunteered their time to take part in this study.

Disclosure statement

The authors declare that there are no conflicts of interest regarding the publication of this article.

Ethical approval

The study was approved by the human research ethics committee of the Doshisha University (No. 15082).

Additional information

Funding

This study was supported by Japan Science and Technology Agency (JST) Regional Industry-Academia Value Program [C7710, to YF].