Hydration for BJJ: What to Drink Before, During and After Class

I spent about four years thinking hydration for BJJ was a competition thing. Something you worried about the week of a tournament and ignored the rest of the year. Then I had a stretch in my early forties where the fourth round of every Tuesday class felt like someone had swapped my arms out, and I put it down to age, or sleep, or the twenty-three-year-old blue belt who kept picking me.

What it actually was, most of the time, was that I arrived at a 7pm class having drunk two coffees and one glass of water since breakfast. I was not dramatically dehydrated. I was just quietly behind, every single session, and I had been for years.

This is the fix, and it is unglamorous. No product solves it. It is almost entirely about when you drink rather than what.

Why you turn up dehydrated without ever noticing

The typical over-40 grappler trains in the evening after a full day at a desk, with at least one coffee and no particular reason to drink water. By the time you are tying your belt you have had maybe a litre since you woke up, and you are about to lose a good chunk of it in an hour.

The gi is the multiplier. Heavy cotton over your whole body is close to the worst possible garment for shedding heat. Sweat that cannot evaporate does not cool you, so you keep producing more of it, and a gi session in a warm room will pull more out of you than the same hour of no-gi. Anyone who has wrung out a jacket after a hard Saturday knows the volume involved is not small.

Then there is thirst itself. The research on older adults consistently finds that thirst becomes a less reliable signal with age, and that people drink less than they need when they are simply told to drink to thirst. That work is on general older populations rather than grapplers, so I would not push the finding further than it goes, but the direction is not controversial. Practically it means the thing you used at 25 to tell you to drink is a weaker instrument at 45. You have to replace it with a habit.

What actually goes first when you are down on fluid

Not strength. That is the surprise. Your grip does not measurably fall off the cliff first, and you can still bench whatever you could bench. What degrades is endurance, how hard a given effort feels, and how well you make decisions late in a session.

The figure you will see quoted everywhere is that performance starts to suffer somewhere around a 2% loss of body mass. For an 85kg guy that is 1.7kg of fluid, which is genuinely achievable in one hard gi class in a warm room. I want to be honest about where that number comes from: it is drawn largely from endurance-exercise research, cycling and running protocols, not from grappling. Nobody has run that study on forty-something purple belts on a Tuesday night. Treat it as a useful rule of thumb rather than a measured fact about jiu-jitsu.

On the mat it is subtle. You do not collapse. You make worse choices in round four, hold positions a beat too long, force a pass you would normally abandon. It reads exactly like being tired, which is why almost nobody attributes it to fluid.

Worth separating two problems that feel identical. If you are blowing hard in round two, that is your aerobic engine, and no amount of water fixes it. That is a training problem and I have written about it separately in cardio for BJJ over 40. If you are fine early and fall apart late, especially on hot days or back-to-back sessions, fluid is a much more plausible suspect.

The 24-hour habit that replaces the pre-class panic

Here is what I actually do now, and it took about three weeks to become automatic.

• Through the day. A bottle on the desk in my eyeline, refilled twice. This is the part that does 80% of the work and it happens nowhere near the gym.
• About two hours before class. Roughly 500ml. Two hours gives you time to absorb it and time to use the bathroom before you are on the mat.
• Ten minutes before. A mouthful, not a bottle. Chugging 750ml at the door means rolling with a full stomach and nothing absorbed yet.
• Between rounds. A few sips each time you swap partners. Not a target, just a default action so you are not making a decision every round.

The ordinary failure here is treating the drive to the gym as the hydration window. It is not. By then you are topping up a tank you spent nine hours draining.

Food fails in exactly the same shape, and usually on the same commute. The snack you grab at 6:45 for a 7pm class is the eating equivalent of chugging a bottle at the door, and it is the reason so many people feel heavy in round three. The timing that fixes it is in what to eat before BJJ.

Do you actually need electrolytes, or is water enough?

For a single hour-long class in a reasonable room, water is enough. I am not going to pretend otherwise in order to make a section sound important.

Sodium starts to matter when any of these are true:

• The session runs past about 90 minutes, or you stay for open mat afterwards.
• The room is hot, or it is summer and the gym has one fan and a lot of optimism.
• It is your second session of the day, or your second day in a row of hard gi training.
• You are a heavy or salty sweater, which you will know because your rash guard dries with white marks on it.

How much sodium you lose varies enormously between people. The commonly cited range in sweat research spans roughly a fivefold difference from one person to another, which is another way of saying that anyone confidently telling you your number is guessing. You cannot copy someone else’s protocol here.

What to use is less interesting than people want it to be. A pinch of salt in a water bottle does most of what a sachet does. Commercial mixes buy you convenience, consistent dosing and a taste you will actually drink, which is a real benefit if plain salty water makes you gag, but they are not doing anything exotic. I am deliberately not sending you to a product on this page, because the honest recommendation for most people reading this is table salt and a bottle they already own.

One thing electrolytes are not is a cramp cure. Mid-roll cramping has more inputs than fluid, and I went through what actually helped in magnesium for BJJ cramps. If cramping is your headline symptom, start there rather than here.

Afterwards, and the back-to-back day problem

The single most useful thing you can do is find out your own sweat rate, once. Weigh yourself before a hard gi class and again straight after, towelled off. Whatever the difference is, that is fluid, and it will probably be more than you expect. Do it twice more across different seasons and you will have a better picture of your own body than any calculator can give you.

Then replace it over the following couple of hours rather than in one go, and eat something salty with it. The sodium in a normal post-training meal does most of the retention work, which is why the guys who eat properly after class rarely have a hydration problem. More on that side of it in BJJ nutrition over 40, and hydration fits into the wider picture in how to recover faster between sessions.

Back-to-back days are where this compounds. Turn up on Wednesday still down from Tuesday and you start the session already in the hole, which is exactly the state I spent years training in without knowing it. If you train three or more evenings a week, the daytime habit stops being optional. It is worth reading alongside how often to train after 40, because frequency and recovery are the same conversation.

The over-40 wrinkles nobody mentions

Medication is the one to take seriously. Plenty of us are on something by our forties, and blood pressure medication in particular can change how your body handles fluid and sodium. I am a purple belt with opinions, not a clinician, and this is the one item on the page where the answer is genuinely not mine to give. If you take anything daily, ask the person who prescribed it what it means for training in a hot room. Do not change your intake or start adding salt because a jiu-jitsu blog said so.

Coffee is mostly fine. The idea that caffeine dehydrates you is overstated for habitual drinkers, and the fluid in the coffee counts. The actual problem is coffee instead of water across a working day, which is a substitution problem rather than a caffeine one. If you also use a pre-workout before an evening class, be aware of what it does to your sleep, which matters more than the fluid question and is covered in BJJ sleep and recovery.

Session load matters more than any generic number. A technical class and a hard round set are not the same demand, and the calories burned calculator is a reasonable way to scale your expectations for a given night.

Two things not to do

Do not cut water to make a division. Masters brackets are reasonably generous, you weigh in wearing your gi under most rulesets, and the gap between divisions is usually not worth it. Dehydrating deliberately to hit a number means competing in a compromised state and taking on a real risk for a competitive edge that, at 47, you almost certainly do not need. Sort out which bracket you actually belong in with the weight classes breakdown and go compete in it. There is more on the practical side in masters competition tips.

Do not drink enormous volumes of plain water very fast. This gets skipped because it sounds unlikely, but drinking litres of plain water quickly while sweating heavily can dilute your blood sodium, and it happens specifically to people who are trying hard to do the right thing. It is uncommon. It is also not something to be casual about. The protection is straightforward: spread your intake out, and when you are drinking a lot because the session was long and hot, include sodium rather than more water.

How to tell whether any of this is working

Three signals, in order of usefulness.

• Round four. This is the one that matters. If the back half of class stops feeling like a different sport, something is working.
• Morning urine colour. Pale straw is the target. This is a rough guide and not a test, and a B vitamin will turn it bright yellow regardless of how well hydrated you are.
• Morning body weight. Not for weight loss purposes, just for stability. If you are consistently a kilo lighter the morning after training than the morning before, you are not replacing what you lose.

Give it three weeks before you judge it. The habit takes longer to build than the physiology takes to respond, and most people quit at day four because nothing has changed yet.

None of this page is medical advice, and nothing on it treats or prevents anything. If you have symptoms that persist, or anything that feels sharp or serious rather than merely tired, that is a conversation for a professional rather than a blog. The general injury picture is in common BJJ injuries, and the wider over-40 training picture lives on the BJJ after 40 pillar.

Frequently asked questions

How much water should I drink before BJJ training?

Around 500ml about two hours before class works well for most people, on top of drinking normally through the day. The two hour gap matters as much as the volume because it gives you time to absorb the fluid and time to use the bathroom before you step on the mat. Drinking a large amount in the ten minutes before warm up mostly leaves you rolling with a full stomach.

Do I need an electrolyte drink for a normal BJJ class?

For one hour in a reasonably cool room, plain water is enough. Sodium becomes worth adding when the session runs past about 90 minutes, when the room is hot, when it is your second session of the day, or when you sweat heavily enough to leave white marks on your rash guard. A pinch of salt in your bottle does most of what a commercial sachet does.

Why do I cramp even when I drink plenty of water?

Because cramping has more than one input and fluid volume is only part of it. Drinking a large amount of plain water while sweating heavily can actually make things worse by diluting sodium. If cramping is your main symptom rather than late session fatigue, that is a separate topic with its own answers and it is worth reading the dedicated write up on cramps.

Does coffee before an evening class dehydrate me?

Not meaningfully if you drink coffee regularly. The fluid in the cup counts and habitual drinkers adapt to the mild diuretic effect. The real problem is drinking coffee instead of water across a working day rather than the caffeine itself. If you use a stronger pre workout before evening class, the effect on your sleep is a bigger concern than the effect on your hydration.

Where to go next

If you fix the daytime habit for three weeks and the back half of class still feels like drowning, the problem is not fluid, it is your engine. Read cardio for BJJ over 40 next and start there instead.