Canadian Cycling Magazine


Fuelling in the heat

- by Matthew Kadey

You may have noticed that our summer riding months aren’t getting any cooler. In the days to come, you’ll likely be facing some saddle time in sauna-like conditions. Although steamy temperatur­es are not typically conducive to optimal cycling performanc­e, certain nutritiona­l strategies can play an important role in helping you perform as well as possible when in the grips of a rubber-melting heatwave. Here are a few things to consider when it comes to your fuelling strategy when the sun won’t let up.

Reach for Carbs

Most cyclists know that carbs are what stoke their engines. During prolonged exercise, your glycogen, a storage form of carbohydra­te found in your muscles and liver, is broken down into sugar (glucose) molecules that can then be oxidized by muscle cells to produce the energy needed for muscular contractio­n. When temperatur­es are soaring, exercising in the heat will put added strain on this valuable energy source. Research that has exposed subjects to endurance tests in the heat has consistent­ly shown that the burn rate for muscle glycogen – a major energy source for high-intensity riding – is greater when temperatur­es are higher, especially in people who are not accustomed to working out in hot climates. An increase in core body temperatur­e and a shift in hormonal balance might be why we rip through our carb stores quicker when the heat is on. Many athletes place more focus on fluids when pedalling in the heat, yet by staying on top of your heightened carb needs, you can delay fatigue.

It’s widely believed that we need roughly 30 to 60 g of carbohydra­tes per hour of exercise. Since the digestion and absorption of nutrition is compromise­d when exercising in a hot environmen­t, it can be a good idea to start fuelling on the lower end of this range to gauge your tolerance and lower the risk for mid-ride stomach woes. If you find your system can handle higher amounts of carbs, consume more to help offset the higher burn rate that occurs when the mercury is rising. Keeping a schedule of more frequent and consistent intake of carbohydra­tes is better than consuming all your calories in one shot. Your carbs can come from any combinatio­n of sports drink (four to eight per cent carb concentrat­ion), gels, chews and various forms of food. Everyone reacts to nutrition differentl­y when exercising in steamy conditions, so it might take a bit of trial and error to determine what works best for you when pushing the pace in the heat. Remember that if you aren’t drinking enough water to go along with your carbs, you’re setting yourself up for gut rot. Aim to drink 350 to 475 ml of liquid for every 30 to 40 minutes of exercise in hot weather.

Since glycogen stores are particular­ly vulnerable when working out in the heat, it’s important that daily food patterns leading up to a race or important training session likely to happen in fiery conditions focus on carb-rich foods, such as whole grains and potatoes, to make sure you hit the start line with fully stocked stores.

Mine the Salt

The average person has roughly two to four million sweat glands. When you’re pushing the pace in the heat, they are going to be working overtime to balance your body temperatur­e. As a result, you’ll be shedding more electrolyt­es, namely sodium chloride (salt) with smaller amounts of potassium, magnesium and calcium also present in sweat. Essentiall­y, think of your body as a big bag of salty water. Electrolyt­es are necessary for proper muscle contractio­n and relaxation as well as helping you absorb, retain and distribute the water you drink for better fluid balance. Salt consumptio­n stimulates thirst, which drives you to drink more and, in turn, maintain better hydration. During spirited rides in the heat, you need to replenish electrolyt­es, particular­ly sodium. Replacing salt losses becomes more of a concern when you push past the onehour mark, particular­ly if you’re sweating greatly. Most people will sweat out between 400 to 1,000 mg of sodium per hour of activity. If you’re exercising in a humid climate or naturally sweat a lot, you’ll shed closer to the higher end of this range.

A number of sports nutrition products – such as sports drinks, dissolvabl­e tablets and a few gels – emphasize their enhanced electrolyt­e content, designed to replace some of what’s lost in sweat and prevent hyponatrem­ia, a dangerous drop in blood sodium levels that can occur when athletes drink plain water to excess. For drinkables, you’re looking for a product that delivers at least 200 mg of sodium per 240 ml of fluid, but be careful about downing too much salt in a single shot. Dumping a bunch of sodium in your body at once can cause fluid retention in the stomach and dreaded gut issues. As with carbs, go with smaller doses of electrolyt­es spread out during your workout. Think ahead when you know you’ll be exercising in an intense climate. A study in the journal Medicinean­dsciencein­sportsande­xercise found that taking in a moderate amount of pre-workout salt can offer a performanc­e benefit for those about to take part in prolonged exercise in a hot environmen­t. So, feel free to break out that bag of salty pretzels for a pre-workout snack.

Frozen Asset

A few studies have found that sucking back a frosty slushy before exercising in the heat can improve performanc­e. The benefit is likely owing to the power that the cold drink has to reduce core body temperatur­e, which makes your pedal strokes seem easier. Before heading out into the furnace, consider blending together some ice cubes and fruit juice or water-rich fresh fruit, such as watermelon, as part of your pre-ride hydration plan.

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