A high carbohydrate diet with a low glycaemic index improves training effects in male endurance athletes

Abstract

The present study investigated the effect of a 4-week high fat low carbohydrate (HFLC-G) versus high carbohydrate low glycaemic (LGI-G) or high glycaemic (HGI-G) diet on power output at lactate thresholds, peak oxygen uptake and peak performance during an incremental cycle test in 28 male endurance athletes. All participants showed improved levels of power output at the lactate thresholds with a more pronounced effect in the HFLC-G and LGI-G. In the HFLC-G peak performance (−11.6 ± 16.3 W) decreased, while in the LGI-G (9.20 ± 13.8 W) and HGI-G (9.89 ± 12.8 W) peak performance increased (p = 0.009). In summary, the LGI-G showed comparable training adaptations as the HFLC-G at submaximal intensities without limiting the ability to perform at high intensities. Compared to a HFLC and HGI diet, the LGI diet in this study seemed to be advantageous during submaximal and high intensities resulting from an improved metabolic flexibility.

Keywords:

• High fat
• high carbohydrate
• glycaemic index
• endurance
• peak performance
• peak oxygen uptake

Acknowledgements

The authors thank all the participants as well as the staff of the University of Freiburg who supported us with the examination.

Author contribution

After the study was finished, D. Z. started as researcher in the Collagen Research Institute, Kiel.

Ethical approval

The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the independent Ethics Committee of the University of Freiburg (protocol code: 136-16 and date of approval: 2017/10/05). The study was registered at the German Clinical Trials Register (DRKS00015521).

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Data availability statement

The datasets generated for this study are available on request to the corresponding author.