Spring training imposes a period of intense physical preparation for professional baseball players with high training intensities, various environmental conditions, and significant fluid and electrolyte losses through sweating. Although hydration is a well-established factor influencing athletic performance, its application within baseball is more nuanced than often assumed. The exertional demands—and therefore hydration needs—vary considerably across positions.
In February, both new and returning professional baseball players report to spring training, gathering at their teams’ respective camps in Arizona or Florida. This critical pre-season period is marked by intense physical preparation, skill refinement, experimentation with new positions or techniques, and team-building activities to foster on-field chemistry. Throughout this time, coaches, athletic trainers, and dietitians closely monitor players to ensure they are progressing toward peak performance. Among the many factors they track, hydration plays a pivotal role—supporting player health, optimizing performance, and accelerating recovery during this demanding period of training.
Four professional baseball teams incorporated Nix into their spring training programs as they headed into the 2025 season. Incorporating this new technology provided an invaluable opportunity to collect baseline sweat data for each athlete, enabling teams to develop personalized hydration strategies tailored to individual needs ahead of the season.
During spring training, both infielders and outfielders wore the Nix Hydration Biosensor throughout a range of practice sessions—including batting practice, pitching drills, fielding drills, conditioning, weightlifting, and base running. These sessions often spanned several hours, placing sustained demands on players’ cardiovascular and muscular systems. The rapid ramp-up in workloads early in the season further amplifies the risk of dehydration, underscoring the need for hydration management.
Data was collected from professional baseball players, with all sessions conducted outdoors in temperatures ranging from 48°F to 78°F and humidity levels between 42% and 95%. The findings revealed that, on average, players lost 20.1 fluid ounces of sweat and 806 milligrams of electrolytes per hour during spring training—highlighting the significant and often underestimated hydration demands of baseball players during this pre-season period.
While all professional baseball players face significant physical demands, these demands vary notably by position. Infielders experience frequent, high-intensity bursts of movement—quick lateral movements, fast throws, and reactive plays on ground balls and advancing runners. Their exertion is largely anaerobic, relying on short, explosive efforts.
Outfielders, by contrast, often spend extended periods relatively stationary but must be ready for sudden, high-speed sprints over longer distances when the ball is in play. These efforts blend anaerobic power with aerobic capacity, especially during extended plays. Outfielders also execute high-effort throws and acrobatic catches that require full-body coordination and exertion.
Data from spring training workouts reflected these positional differences. On average, outfielders lost 20% more fluid and 30% more electrolytes per hour compared to infielders. Players who split time between infield and outfield positions exhibited sweat losses that fell between these two groups.
From a hydration perspective, this data allows coaching staff to identify positional differences and underscores the need for individualized hydration and recovery strategies—even among players on the same team.
Pitchers and catchers represent two of the most physically and cognitively demanding positions in baseball, each with unique exertional profiles. Starting pitchers typically average around 85 pitches per game, a figure that has been declining over the past few years due to strategic bullpen usage and injury prevention measures. Pitchers operate in short, explosive bursts, delivering pitches with maximum force and precision. Though pitchers aren’t constantly moving, the neuromuscular demand is immense, requiring acute focus and efficient recovery mechanisms.
In contrast, catchers ensure a continuous, full-body workload throughout games and training sessions. Wearing full protective gear, catchers perform hundreds of squats, block pitches, execute throws, and maintain constant vigilance over base runners and hitters. Their role demands a combination of muscular endurance, anaerobic strength, and cardiovascular fitness. Our data showed that catchers lost 22% more fluids and 25% more electrolytes per hour than pitchers.
Because catchers lose large amounts of fluid through sweat while in full gear, they often face some of the highest hydration demands on the team.
The difference in exertion between pitchers and catchers reinforces how hydration and recovery plans must account for not just general activity, but position-specific stressors and sweat patterns.
Hydration is critical for all players; however, understanding position-specific demands, gear load, and individual workloads enables strength and conditioning coaches and dietitians to advocate for more precise, proactive hydration strategies for their players, including electrolyte supplementation by athletes.
For these four MLB teams, integrating Nix during spring training was a critical step in establishing personalized hydration baselines for each player. These data-driven insights allowed teams to develop individualized hydration protocols heading into the regular season, ensuring players began competition with a clear, evidence-based plan.
As the season progresses and environmental conditions change, ongoing monitoring becomes equally important. Adjusting hydration and recovery strategies based on variables such as temperature, humidity, and player workload is key to sustaining performance and mitigating dehydration risks.
This advice is not exclusive to baseball and therefore can be applied to athletes across all disciplines. For example, an athlete's sweat profile during cool-weather training can differ markedly from that during hot, humid summer sessions. Periodic sweat testing and monitoring are essential to maintain optimal hydration, support recovery, and safeguard performance year-round.
Do you have a hydration topic that you want to see us cover? Send us a note to info@nixbiosensors.com and we’ll add it to our list of upcoming article content.
Data for this article was compiled based athlete position, workout length and activity type (baseball) for workouts from February 20235through April 2025. This data range was selected to ensure all workouts were from Spring Training. Workouts were pulled from Nix Pro, the group-monitoring app from Nix Biosensors.