In radiation, heat is given off by one object the athlete and is absorbed by the environment or another object that the person is in contact with e. In convection, heat is lost by a person moving through a current air or fluid.

Conduction is the transfer of heat to another object through touch e. When athletes move from a cool or moderate temperature to a hot environment, proper acclimatization to the heat over a two-week period before competing or training at full volume and intensity is probably the most important thing they can do.

Athletes who experience hyperthermia when competing or training in the heat have usually not acclimatized appropriately. Acclimatization can be done by slowly increasing training volume and then intensity and by training at the coolest times of the day.

The body's response to acclimatization is depicted in figure 9. During the first five days of heat exposure, the adaptations of a decreased heart rate and perceived exertion to a training bout will occur.

This is a result of an increase in plasma volume and the start of an increased retention of electrolytes primarily sodium in the sweat and urine. By day 10, core body temperature is decreased as the brain resets and increases sweat rate to compensate during exercise.

The full increase in sweat rate is completed by day Complete adaptation is also marked by a significant shift from anaerobic to aerobic metabolism and thus a greater reliance on fat as a fuel source rather than carbohydrate.

The increased reliance on fat can be highly attributed to a reduction in strain on the body as a result of increased heat removal through a raised sweat rate, a decreased relative exercise intensity, and a decreased number of muscle fibers needed to perform the same amount of work.

Together, these markers are evidence of a complete adaptation to the heat. Ensuring that an athlete takes in adequate fuel and fluid during exercise in the heat is important to minimize injury and prevent premature fatigue.

An athlete moving from a cool or moderate temperature to one that is hot experiences several shifts in metabolism that must be accounted for during training. At rest, RMR is decreased on average by approximately 5 percent.

This is attributed to a decreased need to maintain body temperature because the environment helps do this; however, a hot environment can lead to decreased appetite, and as a result athletes need to be careful that they meet their energy needs.

Training in the heat increases de-mands on the body's metabolism in proportion to the increase in environmental heat. With a significant shift toward a more anaerobic metabolism, initial exposure results in increased carbohydrate use and decreased fat utilization; an increased sweat rate also leads to greater fluid losses.

This happens because the athlete is working at a higher relative percentage of maximal capacity and because an increase in muscle temperature decreases muscle efficiency. But protein still plays an important role post-exercise, as it helps carbohydrate with its role.

The addition of protein to carbohydrate increases insulin production. Insulin is a hormone that facilitates the uptake and storage of carbohydrates and amino acids read more about hormones here.

Thus, you can restore glycogen more quickly and prepare for your next workout, when you consume a combination of carbohydrate and protein and for the record, a few grams of fat does not delay absorption significantly.

A recent trend in fitness and athletics is a push for real food instead of pills, powders and bars. Supplement manufacturers lead you to believe that liquid calories are superior to solid foods because they are absorbed more rapidly.

And in a laboratory setting, this may be the case. But the only reason to use a supplement over a food is convenience. Few of us have live-in chefs and all of us have busy schedules, so quite often carrying a bar or shaker bottle are the only viable options.

When you do have the opportunity to prepare a meal, the extra digestion time compared to a shake will not hinder glycogen or protein resynthesis.

In fact lean meats, fruits, vegetables and whole grains have the benefit of more vitamins, minerals and antioxidants than the contents of your shaker bottle and may be considerably less expensive.

Transportable food options such as chocolate milk, fruit, yogurt, trail mix, homemade energy bars and sandwiches may provide the best of both worlds. As whole foods, they are nutrient dense and unprocessed, yet easy to take to the office or gym. High-water foods such as melons, apples, pears, cucumbers and bell peppers provide the benefit of assisting with re-hydration as well but you still need to drink water before, during, and after exercise.

A quick note regarding chocolate milk, which some tout as the best post-workout option. Low-fat chocolate milk has a great ratio of macronutrients, provides vitamins and minerals and is incredibly cost-effective.

However, most of the research involving chocolate milk is flawed as it has been compared to lower-calorie drinks and it is no more or less effective than a similar drink or food providing the same amount of calories, carbohydrates and protein.

Your goals are an incredibly important consideration when making pre-, during, and post-workout food choices. Two different people, for example—one with weight-loss aspirations, one with healthy weight gain ambitions—should have two different fueling plans.

For a weight-loss plan, total calories and carbohydrate should be less compared to a hypertrophy plan; protein, however, should remain relatively constant see below for more details.

No one lives in a laboratory and almost no one measures every ounce of food or calculates carbohydrates and proteins down to the tenth of a gram. For a pound individual with the goal of maintaining or gaining weight , these recommendations boil down to 90 grams of carbohydrate and 30 grams of protein a carbohydrate-to-protein ratio.

Justin Robinson is a Registered Sports Dietitian and Strength and Conditioning Coach who has worked with athletes from youth to professional level. As the nutrition director and co-founder of Venn Performance Coaching, he specializes in practical sports nutrition recommendations and functional conditioning techniques.

Over the past 15 years, he has worked with athletes from the youth to professional level, including runners and triathletes, MLB players and U. Military Special Operations soldiers. He graduated from Cal Poly, San Luis Obispo with a dual degree in Nutrition and Kinesiology, completed his dietetic internship at the University of Houston and earned his Master's Degree in Kinesiology at San Diego State University.

Sign up to receive relevant, science-based health and fitness information and other resources. Get answers to all your questions! Things like: How long is the program? What You Need to Know About Nutrient Timing. by Justin Robinson on February 08, A small snack one to 2 hours before exercise may also benefit performance.

It is important to ensure good hydration prior to an event. Consuming approximately ml of fluid in the 2 to 4 hours prior to an event may be a good general strategy to take.

Some people may experience a negative response to eating close to exercise. A meal high in fat, protein or fibre is likely to increase the risk of digestive discomfort.

It is recommended that meals just before exercise should be high in carbohydrates as they do not cause gastrointestinal upset. Liquid meal supplements may also be appropriate, particularly for athletes who suffer from pre-event nerves.

For athletes involved in events lasting less than 60 minutes in duration, a mouth rinse with a carbohydrate beverage may be sufficient to help improve performance. Benefits of this strategy appear to relate to effects on the brain and central nervous system. During exercise lasting more than 60 minutes, an intake of carbohydrate is required to top up blood glucose levels and delay fatigue.

Current recommendations suggest 30 to 60 g of carbohydrate is sufficient, and can be in the form of lollies, sports gels, sports drinks, low-fat muesli and sports bars or sandwiches with white bread. It is important to start your intake early in exercise and to consume regular amounts throughout the exercise period.

It is also important to consume regular fluid during prolonged exercise to avoid dehydration. Sports drinks, diluted fruit juice and water are suitable choices.

For people exercising for more than 4 hours, up to 90 grams of carbohydrate per hour is recommended. Carbohydrate foods and fluids should be consumed after exercise, particularly in the first one to 2 hours after exercise.

While consuming sufficient total carbohydrate post-exercise is important, the type of carbohydrate source might also be important, particularly if a second training session or event will occur less than 8 hours later.

In these situations, athletes should choose carbohydrate sources with a high GI for example white bread, white rice, white potatoes in the first half hour or so after exercise. This should be continued until the normal meal pattern resumes. Since most athletes develop a fluid deficit during exercise, replenishment of fluids post-exercise is also a very important consideration for optimal recovery.

It is recommended that athletes consume 1. Protein is an important part of a training diet and plays a key role in post-exercise recovery and repair. Protein needs are generally met and often exceeded by most athletes who consume sufficient energy in their diet.

The amount of protein recommended for sporting people is only slightly higher than that recommended for the general public.

For athletes interested in increasing lean mass or muscle protein synthesis, consumption of a high-quality protein source such as whey protein or milk containing around 20 to 25 g protein in close proximity to exercise for example, within the period immediately to 2 hours after exercise may be beneficial.

As a general approach to achieving optimal protein intakes, it is suggested to space out protein intake fairly evenly over the course of a day, for instance around 25 to 30 g protein every 3 to 5 hours, including as part of regular meals. There is currently a lack of evidence to show that protein supplements directly improve athletic performance.

Therefore, for most athletes, additional protein supplements are unlikely to improve sport performance. A well-planned diet will meet your vitamin and mineral needs. Supplements will only be of any benefit if your diet is inadequate or you have a diagnosed deficiency, such as an iron or calcium deficiency.

There is no evidence that extra doses of vitamins improve sporting performance. Nutritional supplements can be found in pill, tablet, capsule, powder or liquid form, and cover a broad range of products including:. Before using supplements, you should consider what else you can do to improve your sporting performance — diet, training and lifestyle changes are all more proven and cost effective ways to improve your performance.

Relatively few supplements that claim performance benefits are supported by sound scientific evidence. Use of vitamin and mineral supplements is also potentially dangerous. Supplements should not be taken without the advice of a qualified health professional.