Water Redistribution in The Body and Muscles of Young Athletes After a Single Workout Complemented by Water Intake

Background and aim: Individuals practising a sporting activity in the long term show significant changes in the relative masses of fat tissue and other water-containing physiological structures, particularly muscles. Such longitudinal changes of the body composition activated and sustained by sports practices are documented to be health-promoting (in non-agonistic) and performance-improving (in agonistic). However, short-time mass indices variation after each session of sporting activity is limited and inconclusive. It would be worth assessing the effectiveness of the training protocol in sports players for real-time interventions. Hence, our study primarily aims at establishing a post-session evaluation of body index variation. Furthermore, it aims to clarify how a specific training modality affects the body compartments and if the changes affect men and women to the same extent or not. Methods: The study includes 100 healthy young adult athletes showing a 2:1 male-to-female ratio of near age. Hence, one male cohort (N=62, average age: 27.17±5.25 years) and one female cohort (N=38, age: 26.52±5.37 years) were considered for the comparative analysis of the data. Each participant gave the informed consent to undergo two BIA measurements, one pre- and one post- a single training session, within not more than 3 hours apart. At this aim, weight (W), height (H), body mass index (BMI), and the following body composition compartments Fat Mass (FM), Fat-free Mass (FFM, lean mass), Skeletal Muscle Mass (SSM), Total Body Water (TBW), and Extracellular Water (ECW) have been measured and their relative changes analyzed. Intracellular water (ICW) was calculated as TBW-minus-ECW. Conclusion: Given equivalent training conditions we found changes in body composition between pre- and post-session of one single training showed, for each index, the reduction of ECW, and the increase of inferred ICW. The short-term bioimpedance evaluation shown here might be useful in identifying the hydration mode and type of training able to impede dehydration of muscle cells during each exercise session to monitor and improve overall athletes’ muscle performance in competitions and, in the general population at risk of muscle function decline, to prevent dehydration and loss of muscle cells.