Author(s): SOLIANIK, R., ZIDONIENE, K., EIMANTAS, N., BRAZAITIS, M., Institution: LITHUANIAN SPORTS UNIVERSITY, Country: LITHUANIA, Abstract-ID: 526

INTRODUCTION:
Fasting 2–3 days before the weigh-in is one of the most used nutritional strategies for rapid weight loss by combat sports (1, 2). However, the motor behavior changes that occur during acute fasting are not completely understood. It is well established that stress affects motor behavior following an inverted U-shaped relationship (3), and that fasting for 48 h evokes stress in both sexes, with greater stress in females than in males (4). Thus, we hypothesized that (i) fasting-induced stress would affect motor behavior in females and males, and (ii) a higher level of stress in females would result in greater changes in motor function. Therefore, the main purpose of this study was to determine if a greater fasting-induced stress in females would be accompanied with greater motor performance changes (i.e., improvement or decrement) in females than in males.
METHODS:
Fourteen healthy, young, non-obese males and fourteen females underwent a 2-day water-only fasting trial. Changes in subjectively perceived stress, salivary cortisol and plasma catecholamine concentrations were measured. Eye–hand coordination and motor speed were assessed using Grooved Pegboard test.
RESULTS:
Fasting increased plasma adrenaline concentrations in both sexes (p < 0.05). Meanwhile, concentrations of plasma noradrenaline and salivary cortisol, and subjectively perceived stress increased only in females (p < 0.05). Surprisingly, fasting decreased performance of task requiring eye–hand coordination and motor speed only in females (p < 0.05), whereas this task performance was maintained in males group.
CONCLUSION:
Two-day fasting induced a greater psychological and physiological stress in females, and consequently this differences represent a plausible explanation for the sex-based differences observed in psychomotor performance. This sexual dimorphism requires further investigation of possible negative effects of fasting in sports related performance in females.
FUNDING:
This work was supported by the Research Council of Lithuania (Grant No. S-MIP-23–84).
REFERENCES:
1. Artioli GG et al. It is time to ban rapid weight loss from combat sports. Sports Med. 2016.46:1579–84.
2. Ranisavljev M et al. Rapid weight loss practices in grapplers competing in combat sports. Front. Physiol. 2022.13:842992.
3. Metz GA. Stress as a modulator of motor system function and pathology. Rev. Neurosci. 2007;18(3-4):209–22.
4. Solianik R et al. Fasting for 48 h induced similar glucose intolerance in both sexes despite greater perceived stress and decreased estradiol levels in females. Eur. J. Appl. Physiol. 2023.