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15 Feb Pre-exercise hypohydration prevalence in soccer players: A quantitative systematic review

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THEORETICAL FRAMEWORK

Hypohydration is known to decrease plasma volume and increase plasma osmotic pressure. Although the increased plasma osmotic pressure mobilizes fluid from the intracellular space into the extracellular space, this amount of fluid is not sufficient to totally restore plasma volume (Kenefick and Cheuvront 2016). Therefore, skin blood flow and sweating response will decrease during exercise, thereby increasing body core temperature. The decreased plasma volume also results in decreased cardiac output and increased heart rate, leading to a higher physiological strain (Kenefick and Cheuvront 2016). These physiological responses have been demonstrated in hypohydrated soccer players (Nuccio et al., 2017). Regarding soccer performance, hypohydration may cause a significant decrease in aerobic and sprint performance, and dribbling and cognitive skills (Ali et al., 2011). Several studies have examined and reported the prevalence of pre-exercise hypohydration in different soccer populations and different contexts. Nevertheless, the overall prevalence of pre-exercise hypohydration in soccer players is currently unknown.

STUDY OBJECTIVES

This systematic review aimed to report the prevalence of pre-exercise hypohydration in soccer players by analyzing distinct methods of hydration assessment and examining possible differences in the pre-exercise hypohydration prevalence in various subgroups based on sex, performance level, and context.

MAIN RESULTS

After analyzing the results of the 24 studies included in the systematic review, the authors reported that:

  1. Pre-exercise hypohydration prevalence of soccer players ranged from 37.4 to 63.5 % depending on the hydration assessment method.
  2. Pre-exercise hypohydration prevalence was significantly higher amongst male(66.0%) in comparison to female soccer players (49.4%).
  3. Pre-exercise hypohydration prevalence was higher in professional (66.2 %) in comparison to recreational soccer players (55.6 %).
  4. Hypohydration prevalence was significantly lower before a game (41.3 %) in comparison to before a training session (79.6 %).

CONCLUSIONS

The prevalence of pre-exercise hypohydration in soccer players observed in this study is of concern for coaches, sport scientists, and nutritionists. Although differences were observed in the prevalence of hypohydration after a subgroup analysis, it demonstrated a considerable presence among all player groups, regardless of sex, competitive level, and context. This indicates that a lot of progress can still be made amongst all subgroups.

FSI STATEMENTS

  • Irrespective of sex and/or competitive level, there is a high prevalence of soccer players who start both training sessions and matches in a hypohydrated state.
  • Practitioners are advised to constantly monitor the hydration status of players to avoid hypohydration and, consequently, its negative effects on performance.
  • Sport scientists and nutritionists should develop individualized hydration strategies for soccer players.
  • Soccer players should have individualized daily goals to achieve for quantity of liquid ingestion in order to create better hydration habits.

Ali, A., Gardiner, R., Foskett, A., & Gant, N. (2011). Fluid balance, thermoregulation and sprint and passing skill performance in female soccer players. Scandinavian journal of medicine & science in sports, 21(3), 437-445.

Kenefick, R. W., & Cheuvront, S. N. (2016). Physiological adjustments to hypohydration: Impact on thermoregulation. Autonomic Neuroscience, 196, 47-51.

Nuccio, R. P., Barnes, K. A., Carter, J. M., & Baker, L. B. (2017). Fluid balance in team sport athletes and the effect of hypohydration on cognitive, technical, and physical performance. Sports Medicine, 47(10), 1951-1982.