Water, sports drink or shake: what is the difference?
Water provides fluid without sugar or calories. A sports drink generally adds carbohydrate and electrolytes, especially sodium. A protein shake mainly helps meet your daily protein intake. These drinks therefore serve different purposes.
The sports nutrition review by Kerksick and colleagues mainly links the value of carbohydrate drinks to prolonged exercise, especially in the heat. Much of that evidence concerns endurance and does not show that a sports drink improves a typical strength workout.
How should you adjust what you drink during a workout?
Start your workout after your normal meals and drinks. Bring water, drink when thirsty, and notice whether heat, duration or unusually heavy sweating changes the situation. For a very long or hot session, bring enough fluid and take suitable breaks. Do not turn a volume intended for endurance athletes into a requirement for every gym visit.
If you also want to plan food, see what to eat before strength training. For protein, see the guide to protein timing around workouts.
What does the evidence say about hydration and strength?
A systematic review by McCartney and colleagues examined tests performed after experimentally induced dehydration. Results for resistance exercise varied: some muscular-endurance tests improved after fluid intake, while maximal-strength results were less clear. The authors judged the studies too different to support a general rule.
This supports the practical idea of avoiding marked dehydration before training, but proves neither that you must drink at fixed intervals between sets nor that a sugary drink adds reps in a temperate gym.
When should you review your plan for the next workout?
If several comparable workouts go poorly in hot conditions, look at duration, breaks, food and fluids together. Change one factor at a time and compare sets on the same exercise. One workout cannot pin a performance dip on hydration alone.
The guide to measuring strength-training progress explains how to read several workouts. To record useful data, also see the workout log.
Sources and methodology
The review below mainly studies rehydration after fluid loss induced before testing, not sips taken during an ordinary workout. The position paper covers various sports, often endurance exercise. Advice for a typical strength session is therefore practical guidance, not a proven dose.
Frequently asked questions
Do you need a fixed amount at every workout?
No. Duration, temperature, sweat loss and what you drank beforehand all affect your needs. Keep water available and adjust without forcing yourself to finish a prescribed bottle.
Does a protein shake replace water during training?
It also provides fluid, but protein serves a separate nutritional purpose. A protein shake is not required for hydration during every workout.