The effects of creatine and glycerol hyperhydration on running economy in well trained endurance runners

Abstract

Background

Ingestion of creatine (Cr) and glycerol (Gly) has been reported to be an effective method in expanding water compartments within the human body, attenuating the rise in heart rate (HR) and core temperature (T_core) during exercise in the heat. Despite these positive effects, a substantial water retention could potentially impair endurance performance through increasing body mass (BM) and consequently impacting negatively on running economy (RE). The objective of the present study was to investigate the effects of a combined Cr and Gly supplementation on thermoregulatory and cardiovascular responses and RE during running for 30 min at speed corresponding to 60% of maximal oxygen uptake $\left(\dot{\mathsf{\text{V}}}{\mathsf{\text{O}}}_{\mathsf{\text{2}}}max\right)$ in hot and cool conditions.

Methods

Cr·H₂O (11.4 g), Gly (1 g·kg^-1 BM) and Glucose polymer (75 g) were administered twice daily to 15 male endurance runners during a 7-day period. Exercise trials were conducted pre- and post-supplementation at 10 and 35°C and 70% relative humidity.

Results

BM and total body water increased by 0.90 ± 0.40 kg (P < 0.01; mean ± SD) and 0.71 ± 0.42 L (P < 0.01), respectively following supplementation. Despite the significant increase in BM, supplementation had no effect on $\dot{\mathsf{\text{V}}}{\mathsf{\text{O}}}_{\mathsf{\text{2}}}$ and therefore RE. Both HR and T_core were attenuated significantly after supplementation (P < 0.05, for both). Nevertheless, thermal comfort and rating of perceived exertion was not significantly different between pre- and post-supplementation. Similarly, no significant differences were found in sweat loss, serum osmolality, blood lactate and in plasma volume changes between pre- and post-supplementation.

Conclusions

Combining Cr and Gly is effective in reducing thermal and cardiovascular strain during exercise in the heat without negatively impacting on RE.

Keywords:

• Thermal Comfort
• Total Body Water
• Respiratory Exchange Ratio
• Thermoregulatory Response
• Water Compartment

Electronic supplementary material

The online version of this article (doi:10.1186/1550-2783-8-24) contains supplementary material, which is available to authorized users.

Copyright comment

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Electronic supplementary material

The online version of this article (doi:10.1186/1550-2783-8-24) contains supplementary material, which is available to authorized users.

Copyright comment

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgements

The authors acknowledge Oleg Chepelin, Chao Wang and Andreas Anagnostopoulos for their major contribution in the data collection as well as John Wilson for his technical assistance.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

LYB was the primary author of the manuscript. TP was involved in subject recruitment, data collection and helped to draft the manuscript. DM was involved in data collection and editing the manuscript. YPP conceived of the study, participated in its design and coordination and helped to draft the manuscript. All authors read and approved the final manuscript.