A half-marathon training plan usually lasts 10 to 12 weeks. Over that period, you spend far more time training than running the race itself.

Your sports drink strategy is built and tested during those weeks, especially on your long runs. This guide covers your hydration during training, before race day.

Why your long training runs matter most

In a half-marathon plan, the weekly long run usually starts at 10 to 12 km early in the block. It builds up to 16 to 18 km, sometimes 20 km, in the weeks before the race.

Your training pace is often slower than your target race pace. These runs can therefore last 1h30 to 2h or more, even before you reach the full 21.1 km distance.

How your needs evolve over the 10 to 12 weeks of training

This table is a starting point. The exact amount depends on three factors:

• your weight
• the intensity of your run
• your digestive tolerance

Increase your intake gradually, at the same pace as your runs get longer. Waiting until race week to improvise is the scenario to avoid.

Adjust to your weight and sweat rate

A common approximation is to aim for about 0.7 to 1 g of carbohydrates per kilo of body weight per hour on your long runs. Depending on your build, that gives:

• 70 kg runner: about 50 to 70 g per hour
• 55 kg runner: closer to 40 to 55 g per hour

For sodium, weigh yourself before and after a long training run, without drinking or while noting exactly what you drink. Significant weight loss signals a high sweat rate.

In that case, aim for the high end of the 300 to 600 mg of sodium per hour range on your longest runs.

Your tempo and interval sessions

Besides the long run, a half-marathon plan includes tempo sessions and sometimes intervals. A tempo run is a sustained, continuous effort of 20 to 40 minutes.

With the warm-up and cool-down, these sessions often last 50 to 70 minutes in total. They are shorter than your long run, but their high intensity increases your sweat rate.

Show up well hydrated for these sessions. It often matters more for the quality of your session than what you drink during it.

Where Maple MC2 fits into your training

One sachet of Maple MC2 provides 28 g of carbohydrates and 273 mg of sodium. On your long runs late in the block, two sachets spread out cover 56 g of carbohydrates and 546 mg of sodium.

Those amounts fall within the recommended ranges for an effort of more than 2 hours.

Gear to carry your drink on your long runs

Your gear follows the length of your runs.

• First long runs: a small handheld bottle is enough.
• Late in the block: past one hour, a bottle belt or a hydration vest with soft flasks becomes more comfortable than a handheld bottle.
• Refills along the route: if your route passes water fountains or you can stash a bottle halfway, you avoid carrying everything.

Solid nutrition around your long runs

• Before: a meal high in carbohydrates and low in fibre, eaten 2 to 3 hours before the start, fills your glycogen stores. The night before, pasta or rice with little fat remains a safe choice, followed by a light breakfast that morning.
• After: a meal combining carbohydrates and protein within the hour, along with your electrolyte sachet, speeds up muscle recovery before your next key session.

On long runs over 1h30, some runners add a gel or dried fruit to the diluted sachet. It helps most in the weeks when the recommended intake exceeds what a single sachet can provide.

What to do if you get cramps during your long runs

Cramps late in a long run are common. Their link to sodium is less clear than people often think.

Much of the current research points to local neuromuscular fatigue, meaning a muscle that has worked beyond its usual capacity. A simple lack of minerals explains the problem less well.

On your long runs, you can act in three ways:

• keep a steady sodium intake throughout the run
• don't start faster than your planned training pace
• if a cramp hits, slow down and gently stretch the affected muscle

Long runs in the heat versus long runs in cool weather

The season of your training block changes your sodium needs.

• Summer training block: heat and humidity usually call for the high end of the sodium range on your long runs.
• Fall or spring training block: cooler weather reduces that need, without eliminating it on your longest runs late in the block.

Hydration myths in half-marathon training

"I'll test my fuelling plan on race day." It's the most costly mistake.

Your stomach reacts differently under the stress and adrenaline of a race, and what works in training isn't guaranteed on race day. A plan you've never tested is even more likely to go wrong.

"The more I drink, the less I risk dehydration." Drinking beyond your losses dilutes your blood sodium, a well-documented risk in efforts over 2 hours.

Aim to replace your losses, without trying to maximize your water intake.

"My body will adapt on its own if I train enough." Training improves your efficiency, but it doesn't replace a tested fuelling plan.

The tune-up race before the half-marathon

Many training plans include a shorter race, 10 km or 15 km, around week 7 or 8. It lets you test your pace in race conditions.

It's also an excellent chance to validate your fuelling plan with the stress and aid-station rhythm of an official start.

Treat this tune-up race like a long run, repeating what you plan to do on half-marathon day:

• the same sachet
• the same concentration
• the same timing

If something doesn't sit well, you still have 2 to 3 weeks to adjust before your goal race.

How to know if your fuelling plan is working

Three signs show your approach is the right one:

• you finish your long runs without a marked energy drop in the final kilometres
• your pace stays steady from the start to the end of the run
• you recover well in the following days

Other signals point to a plan that needs adjusting:

• a clear slowdown in the last kilometres of every long run
• recurring headaches after the effort
• repeatedly dark urine

Better to fix it on a long training run than to discover it at kilometre 16 on race day.

How to build your routine across the training block

Set a simple routine at the start of your training, then adjust it gradually using the table above. That way, you don't have to decide every week what you'll drink.

Prepare your bottles or belt the night before each long run, so you don't improvise that morning. Session after session, this consistency builds the digestive tolerance you'll need on race day.

If you miss a long run in your plan

A long run missed because of a busy schedule or a minor injury doesn't justify doubling the distance the following week. Resume your normal progression, even if it means staying one more week at a given distance.

Your carbohydrate and sodium intake needs no particular adjustment after a missed week. Simply resume your usual progression, without making up for lost time all at once.

Build your plan before race week

The half-marathon is the first distance in this guide series where training and racing look alike in duration. A plan tested on your long runs and increased gradually over 10 to 12 weeks becomes the most reliable foundation for race day.

The difference comes down to how many times you've tested your drink before the start line.

Your last week of training before the race

In the week before the race, your runs get much shorter to let your legs recover. Keep your usual hydration routine on these shorter runs, even as the distances drop.

Use this week to check your gear as well:

• enough sachets on hand
• a working bottle or belt
• nothing left to improvise the night before the start

Common mistakes in half-marathon training

• Waiting until race week to test your fuelling plan, instead of doing it gradually on your long runs
• Keeping the same intake from the start to the end of the block, without increasing it as your runs get longer
• Drinking too much at once, instead of small, regular sips during the run
• Ignoring body weight and following a plan designed for a runner of a very different build

Want to see how your needs change with your training distance in general? Check out our guide by distance.

Frequently asked questions