Preliminary study on the effect of sex on skin cooling response during whole body cryostimulation (−110 °C): Modeling and prediction of exposure durations
Authors: G Polidori
F Legrand
F Beaumont
B Bouchet
F Bogard
B Abbes
R Elfahem
Journal: Cryobiology (2020)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: Cooling ratio; Protocol duration; Sex effect; Skin temperature.
Affiliations: Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France., C2S, Cognition Health and Society, EA 6291, University of Reims Champagne-Ardenne, France., Cryotera, 2 Rue Jules Méline, 51430, Bezannes, France., Faculty of Exact and Natural Sciences, University of Reims Champagne Ardenne, France. Electronic address: .

Abstract:  In order to determine the required duration of whole-body exposure to extreme cold (-110 °C) in males and females for achieving the same cold-induced response, a mathematical model of skin cooling kinetics was developed. This modeling is derived from the implementation of a new experimental cryotherapy protocol to obtain continuous skin temperature maps over time. Each 3-min whole-body cryostimulation session was divided into six incremental sessions of 30 s carried out over six consecutive days. Seventeen young, healthy subjects (8 males aged 22.6 ±3.0 years and 9 females aged 23.7 ±4.7 years) agreed to participate in this study. The smallest sex-related difference in temperature was found in the trunk area (2.93 °C after 3 min) while the greatest temperature drop was found in the lower limbs (5.92 °C after 3 min). The largest temperature variation was observed between the trunk and the lower limbs, and peaked at 2.67 °C in males and 6.99 °C in females. For both sexes, skin cooling kinetics showed a strong transient exponential type decrease followed by linear regression behavior. It appeared that for achieving the same cold-induced response, the required duration of cryostimulation is longer for males. For example, a trunk skin cooling of -12 °C could be achieved in 125s for females vs 170s for males (+36% longer); for the lower limbs, the same skin cooling magnitude could be reached after 87s for females vs 140s for males (+62% longer). 

Retracted: No

PubPeer comments:
 **Preliminary note:** Another article from the same authors was retracted because the study did not obtain an approval from a Comitu00e9 de Protection des Personnes (CPP) before to start. Which is a serious breach to the French Health Law related to research in humans. In France, CPPs are the only IRBs that can approve prospective researches in human. **Comment on this study:** The ethics statement mentions that : *No permission from the local ethics committee was obtained, since only biomedical clinical studies require this approval according to French law. However, the research participants provided written informed consent and the study was conducted in line with the principles of the Helsinki Declaration and its following amendments.* This is an inaccurate statement. Indeed, in France, all prospective research in humans intended to increase the knowledge in sciences must obtain an approval from a CPP before to start. This study is a prospective research in human. This type of study MUST obtain an approval from a CPP before to start the recruitment. The lack of CPP approval is a serious breach to the French Health Law related to research in humans. It should have been a cause for rejection of the article. Furthermore, the Declaration of Helsinky (article 23) requires to obtain an ethics approval for all study in humans and to be in compliance with the local law. It is not the case here. ,