Hydration, Heat, and Summer Training in Manitoba

By Dr. Michael Minenna D.C., B.Sc., SFMA, FMS

Manitoba doesn't ease into summer so much as flip a switch. One week you're running in a windbreaker, the next it's 30 degrees with prairie humidity. Your body, your training, and your recovery all have to adjust — and the people who get caught out are usually the ones who train through the first heat wave exactly as they did in the cool of spring. A little planning keeps the heat from derailing your summer.

Heat changes the math of a workout

When you exercise in the heat, your body is doing two demanding jobs at once: powering the activity and cooling itself. Blood is diverted to the skin to shed heat, your heart rate climbs for the same effort, and you lose fluid and electrolytes through sweat. The practical result is that a workout that felt easy in May feels much harder in a June heat wave — your usual pace or load is simply more taxing when it's hot.

That's not a sign you've lost fitness. It's your body managing a bigger total workload. Treating a hot-weather session as the same demand as a cool one is how people end up overcooked, depleted, and dragging for days.

Hydration done sensibly

Fluid matters, but the goal is balance, not extremes. Significant dehydration meaningfully impairs performance and your ability to regulate temperature, so going into a session well-hydrated and replacing fluid during and after longer or hotter efforts is worthwhile.¹ For sessions over about an hour, or in real heat, replacing some electrolytes — not just plain water — helps. The simplest practical guide is to drink to thirst, keep an eye on the colour of your urine (pale is the target), and weigh the day's heat into how much you'll need. You can overdo fluids too, so chugging litres "just in case" isn't the answer.

Let your body acclimatize

Here's the reassuring part: the human body adapts to heat remarkably well, but it takes time — typically a week or two of gradual exposure for the adaptations to take hold.² Early in a heat wave, your body simply hasn't adjusted yet, which is exactly when people push too hard and suffer for it. Ease into hot-weather training, and within a couple of weeks the same conditions feel far more manageable.

The familiar principle, with a summer twist

This is the same idea we apply to everything: there are no bad workouts, only too much too soon.³ In the heat, "too much too soon" includes the heat itself as part of the load. Stacking a hard session, a sudden jump in volume, and the first 30-degree day is a triple spike. Pull back the intensity or duration when it's hot, especially before you've acclimatized, and treat the heat as part of the dose rather than something to grind through.

Practical habits cover most of it: train in the cooler parts of the day when you can, build heat exposure gradually, hydrate before and during longer efforts, and respect that recovery takes longer when you've been working in the heat. Sleep and shade are part of training too.

When to back off entirely

Heat illness is the one place to be genuinely cautious. Symptoms like dizziness, nausea, a headache, confusion, or stopping sweating during exercise in the heat are warning signs to stop, cool down, and hydrate — and to seek medical help if they're severe. These are uncommon with sensible training, but worth knowing.

For everything short of that, summer training is one of the real joys of a Manitoba year. Manage the heat as part of your load, build in gradually, and you'll get the most out of the season. At Boreal Spine & Sport we help active people train smart through every season — including the three weeks of summer that actually feel like summer.

References

1. Sawka MN, Burke LM, Eichner ER, et al. American College of Sports Medicine position stand: exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-390.
2. Racinais S, Alonso JM, Coutts AJ, et al. Consensus recommendations on training and competing in the heat. Br J Sports Med. 2015;49(18):1164-1173.
3. Gabbett TJ. The training-injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med. 2016;50(5):273-280.