PepsiCo research highlights growing need for personalized hydration strategies

Researchers in the UK, some of whom were employed at PepsiCo Life Sciences’s Gatorade Sports Science Institute, investigated sweat and fluid/carbohydrate intake responses in 36 elite male professional soccer players training at a high intensity in cool environments during the 2024–25 and 2025–26 seasons.

Results showed that players had varied sweat and sodium losses, while carbohydrate intake varied widely and often fell below recommendations.

“Practitioners can utilize the present data to inform the hydration recommendations for elite soccer players when training at high intensity in cool environments,” the researchers wrote. “This is important, as hydration may be perceived as less important in cool environments than during training in the heat.”

Hydration and sweat losses in elite soccer players

During high-intensity soccer training, players lose water and sodium through sweat, which can reduce blood plasma volume and make it harder for the body to regulate temperature. These changes can increase cardiovascular strain and potentially impair physical performance. Drinking fluids helps maintain fluid balance, while replacing sodium supports fluid retention and electrolyte balance.

Previous research has identified substantial individual differences in sweat rates, sodium losses and fluid intake, including in cool environments. However, research exploring the variable demands of elite soccer players is more limited, the researchers of the new study noted.

They therefore set out to investigate sweat rates, sweat sodium concentrations, fluid intake and carbohydrate consumption in elite male players during high-intensity training in cool conditions, hypothesizing that players would show high sweat and sodium losses, varying levels of hypohydration, and carbohydrate intake below 30 g per hour.

Dehydration risk and low carb intake in elite soccer players

The researchers weighed the 36 players before and after 70 minutes of training, correcting for fluid intake and urine or stool losses to calculate sweat rate and changes in body mass.

They measured sweat sodium concentration by attaching absorbent patches to players’ upper backs and thighs and analyzing the collected sweat with a portable ion-selective electrode analyzer.

During training, players had free access to water, carbohydrate-electrolyte drinks and electrolyte beverages, allowing researchers to assess fluid and carbohydrate intake in grams per hour.

The researchers also collected pre-training urine samples from 11 players and measured urine-specific gravity using a digital refractometer to assess hydration status.

Results showed that outfield players sweated an average of 1.5 L/h, compared with 0.7 L/h for goalkeepers. Sweat sodium concentrations varied considerably (21–49 mmol/L), and 17% of players lost more than 2% of their pre-training body mass. Players who trained at higher intensities lost more sodium chloride.

Carbohydrate intake also varied widely (0–25 g/h), with 23 of the 36 players consuming no carbohydrates during training. The researchers noted that consuming 30–60 g/h may improve performance during intense 60–70-minute training sessions.

“The findings of this study indicate that the ad libitum hydration strategies employed by elite male soccer players training at high intensity in a cool environment may not be sufficient to prevent hypohydration of <2% pre-exercise body mass in all players,” the researchers concluded.

They noted that future research should investigate personalized hydration and carbohydrate-fuelling strategies that account for individual sweat rates, sodium losses and training demands to help optimize performance.

Source: Nutrients; doi: https://doi.org/10.3390/nu18203459; “Fluid Balance, Sweat Na+ Losses and Carbohydrate Intake in Elite Male Soccer Players Training in Cool Environments.” Authors: V. Sabou, et al.