As you exercise, your muscles create heat. To keep your body safe as you begin to build up internal heat, your body increases your sweat rate to remove heat from the inside of your body – this happens through evaporative cooling. Overtime, as you become dehydrated (from fluid loss), blood volume decreases. As a result, blood gets thicker. And the more blood going to the skin means less blood going to your heart which means less blood to your working muscles. To maintain cardiac output (the amount of blood pumped by the heart per minute), heart rate increases in order to supply the working muscles with blood. But due to a decline in blood availability (because of cooling), less blood is available to go to the working muscles. When the body can no longer take care of all of its responsibilities (remember - all of this is happening so you don't die in the heat), your body will start to slow down by shutting down to keep you safe. If you ignore the signs of overheating, heat builds up in your body, your core temp increases and you are at risk for overheating and may experience heat stroke.
Here are a few helpful tips for exercising in the heat:
Acclimatization
Complete heat acclimatization requires up to 14 days but body systems of the body adapt at varying rates. Be mindful that every time you exercise in the heat, you gain more tolerance but it could take at least 2 weeks for you to feel more comfortable exercising in the heat. But there's no point suffering in the heat if you are unable to complete a quality workout, which means sometimes you just need to exercise indoors.
Change in physiology
It is very important to lower the intensity during the first 2 weeks of exercising in the heat (ex. early summer) as your body is trying to improve control of cardio functioning. Be mindful that acclimatization will require you to reduce your effort/intensity so be OK with seeing slower paces in the first few weeks of acclimating. You will likely notice an increase in cardio strain and your perceived exertion will increase. You may also feel more tired, fatigued and exhausted than normal. Positive cardio adaptations occur in the first 5-10 days whereas changes in sweating mechanisms can take 10-14+ days.
Training modifications
Consider splitting up your workout (half outside, half indoors). Find shady areas to exercise. Opt to exercise indoors when the humidity is very high. Or, try to workout when it's not as hot (early morning or early evening). If you try to push your normal efforts in the heat, your body cannot safely adjust to the heat.
Hydration
The symptoms of underfueling and dehydration are not pleasant.
A sport drink provides a practical and easy way to obtain fluids, electrolytes and carbohydrates - in the precise formulation - to optimize digestion and absorption. If you are exercising in the heat for more than an hour or you are sweating perfusely in the heat, opt for a well formulated sport drink (at least 30g carbohydrates, 240mg of sodium and at least 16 ounce water per hour).
Although your daily diet helps to keep you nourished and fueled, the diverse nature of hot and humid weather validates the importance of consuming well-formulated sport nutrition drinks during specific outdoor workouts.
Females
Females who menstruate regularly each month may notice an increase in thermal strain during exercise during the luteal phase (high hormone phase) before and during menstruation. The increase in progesterone causes body temperature to increase in preparation for the fertilization of an egg. When fertilization does not occur, estrogen and progesterone decrease before the follicular phase. The high concentration of progesterone during the luteal phase affects fluid balance, causing females to feel bloated from fluid retention. Additionally, whereas females are more likely to feel cold during the estrogen-dominant follicular phase, progesterone acts on the hypothalamus (temp control center) which increases body temperature. Females may feel warmer than normal, which makes it more difficult to dissipate heat (although a helpful physiological response for racing in cooler weather events). Females should be mindful of how the body responds to training in the heat, specifically in the 7-10 days before menstruation and adjust efforts accordingly.
Minimize heat stress
There are several ways to minimize heat stress. Your exercise gear should be breathable, light, wicking and should help you stay cool and minimize exposure to the sun. Your clothing should protect the areas of your body that are most exposed to the sun (ex. back, neck, shoulder, face). Always wear broad spectrum sunscreen when you train outdoors and reapply. Wear a cooling towel around your neck and regularly re-wet throughout your run. Bring a sport drink with you and sip consistently (every 10-15 minutes). Search for shaddy sections to run and select "cooler" times in the day to workout.
Know the warning signs
Identify the warning signs of heat cramps (muscle cramps), heat exhaustion (thirst, profuse sweating, fatigue, pale and cool skin, weakness, headache, nausea, chills/goose bumps, cessation of sweating, faintness, dizziness) and heat stroke (strong and rapid pulse, hot and dry skin, confusion). If you suddenly feel like you are experiencing a heat related illness, stop exercising, get into a cool environment and drink electrolyte-based liquids. An extreme loss of appetite, excessive sleepiness, headache, chills or abnormal fatigue during or post workout can all be signs that you are not properly hydrating (or fueling) during your workout.
from Trimarni Coaching and Nutrition https://ift.tt/ok4DKX1
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