Working Out in Hot Weather
Physical activity during hot weather represents great stress for human body - running, cycling, hiking, swimming or just physically working can be demanding for the body, but when done in hot weather, can be even very dangerous.
During physical activity body temperature rises and one of the tasks that must be done is to keep body temperature within biological limits - therefore, we sweat. Higher the temperature, heavier the physical activity, more clothes we have etc. body will sweat more. More sweat means more liquid on the skin that can evaporate - water evaporation cools the body and keep the temperature at acceptable levels. This heat is also known as the heat of vaporization or heat of evaporation.
Sweat is combination of water and various minerals, also known as electrolytes - mostly sodium and magnesium but other minerals as well. A composition of sweat vary from person to person, but typically a liter of sweat contains: 1.48g of chloride, 1.15g of sodium, 0.23g of potassium, 0.02g of calcium, 0.05g of magnesium and other compounds in smaller quantities.
Fluid loss can have various effects on human body, depending on the amount of lost liquid. These effects are individual, but generally, effects of liquid loss on human body depending on body weight percentage lost as sweat:
- 2% loss of body weight as sweat results in impaired performances,
- 4% loss of body weight as sweat results in declined ability of muscles to work,
- 6% loss of body weight as sweat results in total heat exhaustion,
- 8% loss of body weight as sweat results in hallucinations,
- 10% loss of body weight as sweat results in heat stroke, circulatory collapse and death.
Capability to perform physically simply fades away as the body loses more liquid and electrolytes, up to the point where physical activity of any kind is no longer possible - this is very dangerous level of dehydration and mineral loss that can lead to death.
High Temperatures - Hot Weather
Tolerances for high temperatures vary and it is very individual. Slim people often tolerate higher temperatures more easily than heavier or bulkier people - this is due to higher skin surface to body volume ratio. Also, there are other factors that determine how we feel on any given temperature, like are we on the sun or in the shade, color and type of the clothes, is there any wind of any kind, type of physical activity, age, height, weight, body fat percentage, ancestry and habits etc.
Obviously, high temperatures are hard to define. But, people often forget to mention air humidity - amount of evaporated water in air. More humid the air, sweat from the skin will harder evaporate, thus reducing cooling effect - to compensate that, body will sweat more and we will lose more liquids and more minerals. This decrease even more body's capability to perform physically.
Skin Protection During Hot Weather
During hot and sunny days, skin should be protected from dangerous UV light. It is highly recommended to use protective creams with sun block factor of 25 or higher, especially if you are planing to be exposed to sun radiation during critical hours - between 10:00h and 16:00h. During these hours, even reflected UV radiation can cause skin burns, so be careful.
Also, proper clothing can help a lot in protecting body from sun radiation and heat in general.
Lightweight Clothing for Hot Weather
If you are physically active during hot weather, than you need some lightweight clothes. These clothes are mostly made from natural materials like cotton, but modern materials are also something to consider. Mixed materials are most often the best choice.
For activities during daylight, white and similar bright colors are recommend for decreasing the heat from the sun - dark colors absorb sunlight and in moderate regions heat from the sun can reach up to or even more than 1 kW per square meter (93 W per square foot) - you don't need this additional heat during high temperatures.
Many people opt for short sleeve shirts during hot weather - this is good choice for activities in shades. But, if you are out in the open, long sleeve shirt with wide sleeves and bright colors can be surprisingly efficient in repelling sun heat from the body. Long sleeve shirts for hot weather are made from suitable materials that provide plenty of fresh air near the skin to promote evaporation of the sweat and thus promote cooling effect, plus they protect much more skin area than short sleeve shirts.
Hats are not only fashion accessory during hot weather - they protect head from direct sun light and help in cooling head by allowing air to pass near the skin. Wide hats are great for protecting head, neck and even shoulders, but they can interfere with physical activity - choose hats according to your needs.
Sun glasses are needed for eye protection, depending on the individual preferences and sensitivity. When wearing sun glasses for longer period of time, be careful when taking them off. Proper sun glasses can be very expensive, but what you pay is often what you get ...
Staying Hydrated in Hot Weather
Staying hydrated is one of the most important things to have in mind in hot weather. When you are sweating, you need water and in very hot weather, you need plenty of it. Drinking water is important for replenishing lost water, but also for cooling body's core. This doesn't mean that one should drink freezing water during hot weather - on contrary, drinking too cold water can upset stomach and can cause diarrhea and other stomach related problems. Last thing that you need in hot weather is to increase loss of liquid due to stomach problems.
Replenishing lost minerals is also very important. Isotonic and similar drinks with minerals like sodium, magnesium, potassium etc prevent muscle cramps and can significantly prolong ability of the body to perform in hot weather. There are also pills and tablets that can help in replenishing electrolytes.
Water vs Isotonic Drinks
Water contains - water. Isotonic and similar drinks contain simple carbohydrates like glucose and various minerals in different proportions:
- hypotonic drinks contain water, minerals and carbohydrates. Carbohydrate content is less than 4-5%
- isotonic drinks contain water, minerals and carbohydrates. Carbohydrate content is around 6-8%
- hypertonic drinks contain also water, minerals and carbohydrates. Carbohydrate content is above 8%
It is important to note that carbohydrates up to 6-8% percent in the fluid like water, don't influence rate of absorption. After that level, the higher the carbohydrate percentage in the fluid, the slower the rate of absorption. So, if you are engaged in physical activity during hot weather, you need much more fluid to keep hydrated than simple carbs to keep blood sugar levels stable - take hypotonic drinks or combine them with isotonic drinks. If you are engages in physical activity during normal weather conditions and you are not sweating a lot, than isotonic or hypertonic drinks can be taken in order to boost energy levels.
Nonetheless, it is highly recommended to take pure water from time to time in small sips.
Protein Intake and Hot Weather
If you are engaged in some sport event that last less than 2-3 hours, taking any protein in the form of solid food is not advisable. Such food will take relatively long time to digest and can hamper physical performance. Also, to digest protein, body needs fluids, so during protein digestion, water absorption can be slowed down. Not so good when sweating heavily.
If you are physically active for longer periods of time and you can't have break for proper meal and resting (at least 45 - 60 minutes), take really small portions 'on the run' of solid meals (mostly protein + carbs) with some water during the meal and have water every 10 - 15 minutes to keep your body hydrated. Taking such meals will help you keep nitrogen (amino acids) and blood sugar levels more or less stable. If preparing and taking such meals is not practical than consider taking various Meal Replacement Powder (MRP) shakes or bars when needed.
Also, having few tablets of BCAA, EAA or complete amino acids from time to time can help in keeping strength and stamina high.
Rowing in Hot Weather
When rowing outside, row early in the morning or late in the evening. Be sure to have enough water and other liquids and just in case, a protein bar or Ready-to-Drink meal replacement or some protein/energy shake or anything similar. Also, a good multimineral and multivitamin tablets are recommended.
Some rowers consider all of this as a burden, except perhaps a bottle of water, but if you want to keep your body functioning properly during hot weather while rowing for extended period of time, body simply must have what it needs - water and macro- and micronutrients.
Fortunately, when rowing on the water, there is plenty of air circulation around the body, which decreases the sweating.
When rowing indoors, during summer, be sure to have AC unit on, but stay away from direct stream of cold air. Adjust temperature according to your preferences and enjoy your rowing workout. Just to be sure, have a bottle of water with you.
Running in Hot Weather
Running in hot weather provides plenty of air around the body - cooling effect due to sweating is increased. But due to running, produced energy is also much higher when compared with walking or similar activities. Bottom line - running will significantly increase sweating and loss of water and minerals. For the running events that last longer period of time proper hydration in the form of water and other drinks is absolutely needed in order to keep body functioning.
Skin protection in the form of high sun block factor creams, hats and glasses is highly advisable.
Cycling in Hot Weather
Cycling provide much more air around the body when compared with running or walking. Energy expenditure depends on intensity of cycling. Generally, it is much easier to take fluids and liquid food when cycling than when running - you can have food, water and drinks with you all the time, while this is much harder when running. So, fluids and food can be taken when desired.
Protection in the form of glasses and helmets is recommended. Modern cycling suites promote sweat evaporation and keep body cool as much as possible - same thing happens with some running suites, but effect of cooling is smaller due to less air speed when running.
Hiking in Hot Weather
Hiking in nature usually lasts all day long. It is very important to have proper wide hat to protect head, neck and as much shoulders as possible. Bright colored clothes protect rest of the body from strong sun radiation. Hikers usually have backpacks with water, various drinks and foods. Taking fluids in regular intervals will keep body hydrated, while taking carbs and protein in various forms of food can help in providing energy for all day long activities.
Note that depending on the hiking track, hikers often can climb significant heights where sun radiation is even stronger, but air temperature can be much much lower - lower temperatures can trick hikers about sun radiation, so be very careful regarding sun burns.
Swimming in Hot Weather
Swimming is great activity for fitness and staying fit during summer. Body weight is supported by water and body strength is entirely used for positioning and propelling body trough the water. When swimming, energy expenditure due to type of physical activity is reduced, but swimming is not something that most of the people do on regular basis - muscles are not accustomed to prolonged swimming activities and can get tired quickly.
Anyway, when swimming, fluid loss in the form of sweat is minimal and depends on water temperature. Swimming in moderately warm water (25°C/77°F) provides adequate 'cooling' for the body and swimming can last for longer period of time. Swimming in the cold water (20°C/68°F or less) will not only stop sweating, but when done for longer periods of time can cause body core temperature to drop. Not recommended without protection suits, although this vary significantly from individual to individual. Swimming in the warm water (30°C/86°F or higher) can cause fluid loss in the form of sweat since water flow can't provide enough cooling- again, this is very individual. Swimming in very warm water (35°/95°F) can cause body to overheat - be very careful.
Wearing hats and sun glasses when swimming - if your swimming style allows this and you plan to stay in the water longer period of time, then it is recommendable to wear at least a hat.
Sun creams with higher sun block factors are recommendable regardless of swimming styles, especially for face, neck, shoulders, chest and upper back. Today, plenty of sun creams state that they are water proof, but recommend applying new protective layer of sun cream right after swimming ...
Regardless of your physical activity during hot weather - be careful. Keep your self protected from strong sun radiation, hydrate your body by drinking water and other fluids and watch out for symptoms of overheating - when this occurs, stop whatever you are doing, go into the shades, sit or lay down and cool your self by drinking water and fluids. Often, spraying (cold) water over exposed skin can help in cooling down - if you do this, do it slowly and gradually since sudden drop in temperature of periphery blood can cause other severe health problems.
When engaged in extreme physical activities, it is recommended not to be alone - if something happens to you, other people can help. Also, if something happens to others, you can help them ...