The Ottawa Army Run is just around the corner, it takes place on Sunday, September 21, 2025. Whether you’re signed up for the 5K, 10K, or half marathon, one of the most important (and often overlooked) parts of your race-day strategy is hydration. We know preparation isn’t just about training your legs and lungs, it’s about fuelling your body so you can perform at your best.
Remember when we’re talking about hydration the things most people immediately think about it water. While the consumption of water is very important we also want to make sure you have the ideal amount of electrolytes.
An electrolyte is a mineral that carries an electric charge when dissolved in body fluids like blood, sweat, and urine. Your body needs them for a ton of critical functions, especially during exercise. The main concern is water without eletrolytes doesn’t allow for proper absorption. Always remember, it’s not about what you consume, it’s about what you absorb.
Here are our top hydration tips to help you crush your Army Run:
1. Start Hydrating Days Before
Hydration isn’t something you can fix the morning of the race. In the 2–3 days leading up to race day, make a conscious effort to sip water consistently throughout the day. Aim for at least:
- 2–3 liters of water per day (adjust based on your size, sweat rate, and activity level). For example a smaller 115lb female should be around 2L/day while a 6 foot 225lbs male should be around 3L/day.
- Include electrolytes if you’re training or sweating a lot in the days before. This is especially true for sodium, potassium, and magnesium but more about that later.
- The best way to figure out how much actual water you need is to weigh yourself naked. Go for a run, then re-weigh yourself naked to see how much water you lost and then calculate the correct amount of electrolytes and water to consume.
- Here is a super simple DIY hydration drink that you can make at home (if you’re in a pinch just the lemon and salt will work):
- ½ tsp salt (1,150 mg sodium)
- ¼ tsp potassium chloride (like NoSalt) (~700 mg potassium)
- ¼ tsp magnesium citrate powder (optional, ~100–150 mg magnesium)
- Juice of ½ lemon or lime
- 8–16 oz water
2. Check Your Urine, Not Just Your Bottle
A simple way to track hydration: look at your urine color. Pale yellow = hydrated. Dark yellow = time to drink. Clear all the time = you may be overdoing it.
3. Race Morning Hydration
On the morning of the Army Run:
- Drink 500–750 mL of water about 2–3 hours before the start.
- Have a light snack with some carbs and a pinch of salt if you usually eat before runs.
- About 30 minutes before the race, sip 150–250 mL of water to top things off.
Avoid chugging huge amounts right before the start—you don’t want to be hunting for porta-potties at kilometer two. This is a common issue I see with new runners. 400-600ml is the most amount of water you can absorb in one sitting so consuming more doesn’t help.
4. During the Race
- For 5K runners: Most don’t need to take in fluids during the race unless it’s unusually hot or you’re prone to heavy sweating. Hydrate before and after and you’ll be fine.
- For 10K runners: Use water stations if you feel thirsty, usually once or twice during the race.
- For half marathon runners: Plan to sip water or sports drink every 15–20 minutes. Take advantage of aid stations. If you’re a salty sweater (you see white streaks on your clothes after training), consider a sports drink or electrolyte tabs to replace sodium.
5. Post-Race Recovery
The finish line is just the beginning of recovery. Within 30–60 minutes after your run:
- Drink 500 mL of water plus some electrolytes.
- Pair that with a protein + carb snack (like chocolate milk, a banana with peanut butter, or a protein shake and fruit).
- Keep hydrating steadily for the rest of the day to replace what you lost.
6. Ottawa Weather Factor
September in Ottawa can be unpredictable—sometimes cool, sometimes hot and humid. It’s really hard to tell. Based on the weather lately I would bet on a hot but dry day. Check the race day Ottawa forecast the night before and adjust your hydration plan accordingly. If it’s going to be warm, lean a little more on fluids and electrolytes.
Final Word
Hydration is simple, but it makes a massive difference in your performance and recovery. Treat it like part of your training, not an afterthought. By showing up hydrated and fueling smartly, you’ll set yourself up for a strong Ottawa Army Run, whether you’re chasing a personal best or just soaking up the atmosphere. If you have additional questions let us know.
Good luck out there, we’ll be cheering you on!