Four ideas do most of the heavy lifting in hydration science. Get them right and you'll make better decisions for yourself and the athletes you support.
Roughly 60% of the human body is water, and every physical and cognitive system depends on it. Blood volume, joint lubrication, temperature regulation, nutrient transport, and nerve signaling all rely on adequate fluid.
Even small losses matter. Research has repeatedly shown that fluid losses of just 1–2% of body weight can measurably impair endurance, reaction time, and decision-making.
Dehydration is rarely dramatic. It's usually quiet — a slight drop in performance, a slower recovery, a heavier feeling at practice. That's what makes it so easy to miss.
Hydration is a performance input, not just a safety concern. Treating it that way changes how you plan practice.
Electrolytes are charged minerals — primarily sodium, potassium, and magnesium — that regulate how fluid moves in and out of cells. Sweat pulls them out. If you don't replace them, absorption of new fluid slows down.
The single most important electrolyte for hydration is sodium. When sodium and glucose are consumed together, they activate a specific transporter in the gut wall that pulls water into the bloodstream faster than water alone.
This mechanism — sodium-glucose co-transport — is the foundation of oral rehydration science and the reason well-formulated sports drinks outperform plain water during hard activity.
An athlete drinking only water during a hard practice may actually dilute sodium levels, worsening cramping risk. Electrolytes aren't optional in the heat.
Reaction time, decision speed, and executive function are all sensitive to hydration status. Studies of athletes and soldiers have shown measurable declines in tasks like target identification and reaction time at just 2% fluid loss.
That matters because most sports are decision-heavy. A wide receiver reading coverage, a shortstop reacting to a line drive, a defender picking up an off-ball run — these are cognitive tasks under physical load.
Acuity was built with this in mind. Beyond fluid and electrolytes, the formula includes L-theanine to support focus without stimulants, and B vitamins to support normal energy metabolism.
Late-game mistakes are often blamed on 'losing focus.' Sometimes they're blamed on the wrong thing — the athlete is dehydrated.
The 30 minutes after activity is the most productive window for rehydration. Sodium drives fluid retention, so the drink you use matters — plain water passes through faster and does less to restore balance.
A common rule of thumb: for every pound of body weight lost during a session, replace roughly 16 ounces of fluid. Weigh in, weigh out, and adjust accordingly.
Recovery isn't just about the current session. It's about the next one. Athletes who rehydrate well after practice show up better prepared for tomorrow.
A five-minute post-practice hydration routine is one of the highest-leverage habits a program can build.
A curated list of the studies we lean on most, with plain-language takeaways for coaches, athletes, and parents. Updated regularly.