Tag Archives: sports nutrition

Sports physiology in the Tour de France

 

This week marks the start of the 2017 Tour de France. This year the race covers 2200 miles in 21 days of racing, comprised of team and individual time trials as well as stages through cities, countryside, and mountains of France. The Tour de France is interesting to me because it provides an excellent opportunity for a short lesson in sports physiology. Which I did in my Health & Fitness column in the Aiken Standard this week.

Tour de France


All the riders in the Tour are exceptionally fit since their bodies have adapted to years of dedicated, intense training. Endurance sports like cycling are dependent on the delivery of oxygenated blood to the muscle to produce ATP, the energy needed to sustain exercise. The riders have large, strong hearts, resulting in the ejection of more blood to the muscle. Within the muscle there is an increase in the number of capillaries, the small blood vessels that deliver blood to the muscle, and mitochondria, the part of the cell that produces most of the ATP. Together, these adaptations allow the muscle to produce more ATP without fatigue, allowing the athlete to exercise at a higher intensity for a longer time.

But training isn’t the only reason these athletes can sustain such intense exercise for so long. Proper nutrition, especially what the athletes eat and drink before, during, and after each stage, also plays an important role. Intense endurance exercise like cycling relies on carbohydrates, in particular, muscle glycogen, as a fuel. Muscle glycogen is a storage form of glucose, sugar that the muscle converts into energy. During prolonged exercise that lasts several hours, muscle glycogen levels can be severely depleted.

Eating carbohydrates before exercise can boost muscle glycogen levels, so cyclists eat carbohydrate-rich foods for breakfast before each stage. They also consume carbohydrates in the form of sports drinks (think Gatorade) and energy bars prior to starting. In fact, they start replenishing their muscle glycogen immediately after finishing the previous day’s ride. This usually begins with a recovery beverage, which may contain some protein for more rapid muscle glycogen synthesis, and extends through carbohydrate-rich meals and snacks that afternoon and evening.

During exercise it is crucial to maintain adequate blood glucose levels, which tend to drop since the muscle is using so much as a fuel. Failure to replenish blood glucose results in what cyclists call “hitting the wall” or “bonking,” which is like your car running out of gas. To prevent this, glucose must be replenished, typically with sports drinks, energy bars, or a sugary mixture called goo.

Prolonged, intense exercise, especially in the heat, results in a high sweat rate which can lead to dehydration. Sweat loss of several liters per hour is not uncommon during cycling, so fluid intake is essential. This means that cyclists spend a lot of time drinking water while they ride. Sports drinks are also commonly used since they contain carbohydrates and electrolytes in addition to water.

Endurance events like cycling, especially multi-stage events like the Tour de France, highlight important concepts of sports physiology. Even though you may never compete at that level, understanding how training can improve your endurance is relevant if you cycle—or run, walk, or swim—for exercise. Knowing how proper nutrition before, during, and after exercise can improve performance can help you make better decision about what to eat. Hopefully, it also gives you a greater appreciation for the science that goes into a performance like the Tour de France.


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Santa’s exercise plan for functional fitness and health

Since Christmas is only a few days away our attention is naturally focused on one person: Santa Claus. Have you ever wondered how Santa gets in shape for his yearly sleigh ride to deliver gifts to good boys and girls around the globe? Like many elite athletes, Santa does not publicly discuss his training or his fitness. There are certainly no published studies that report his one repetition maximum strength or his maximal oxygen uptake. Given this lack of information, I attempted to make an educated guess about Santa’s training, fitness, and health. This is the topic of my Health & Fitness column in the Aiken Standard this week.

santa


By all accounts, Santa is overweight. While we don’t know his body mass index, he would probably be considered obese. Furthermore, he appears to have a large waist circumference, indicating a high level of visceral fat. This suggests that Santa is a high risk for type 2 diabetes, high blood pressure, and heart disease. This combination can lead to a heart attack and, possibly, death at a relatively young age.

But Santa has avoided this fate, and seems to be living a healthy life. His secret, no doubt, is regular exercise. There is good evidence that maintaining a high level of physical activity can “undo” some of the negative effects of obesity and can reduce the risk of death in people who are obese (and everyone else).

Like many athletes, Santa trains in the “offseason” to get ready for his annual Christmas Eve journey. Santa’s training likely includes endurance, strength, and flexibility exercises. In order to visit every home around the world in one night, Santa moves quickly. This suggests that he has a high maximal aerobic capacity as well as good endurance. This is a result of both high-intensity interval training and long-duration, lower intensity training, similar to what a marathon runner might do. Evidence for his good aerobic fitness is shown by the fact that he flies away from each home with a hearty “ho, ho, ho.” If he were out of shape, he would be too short of breath to speak, much less give such a robust farewell.

Santa must also dedicate training time to improving his strength. His sack of gifts is certainly very heavy and he repeatedly carries it up and down chimneys. In addition to traditional weight lifting, Santa probably also engages in plyometric training, which involves explosive movements that develop muscle power. Santa must also have good flexibility in order to squeeze through narrow spaces and move quickly without pulling a muscle. This is the result of stretching and, likely, other exercises such as yoga.

Santa is also educated about sports nutrition. The cookies and milk you leave for him are more than a reward for delivering gifts at your house. The carbohydrates (sugar) in the cookies help Santa maintain his blood glucose to delay muscle fatigue. Some research suggests that combining carbohydrates with protein is even more effective, so the glass of milk is a good addition. Of course, Santa could have a specialized sports drink, but that doesn’t make for such a good story.

We can learn an important health lesson from Santa. Even though he is overweight, through regular exercise, Santa has reduced his risk of health problems and maintained his fitness at a level that allows him to complete his necessary activities. Like Santa, all of us can benefit from being physically active, whether we are overweight or not. He would likely be healthier and be able to perform his job better if he lost weight, but I’m not about to tell Santa what to do!


Nutrition, exercise, and health information can be confusing. 
But it doesn't have to be that way.
What can I help you with?
 drbrianparr@gmail.com | http://twitter.com/drbrianparr

How much protein do you need?

Recently I wrote about carbohydrates, fats, and protein, the major sources of energy in our diet. Getting sufficient amounts of these nutrients is essential to promote good health and exercise performance. Given the current trend of low-carbohydrate diets and an emphasis on protein for everything from fitness to weight loss, many people have wondered about how much protein they should eat. This is the topic of my Health & Fitness column in the Aiken Standard this week.


Good food display

As you might expect, protein needs vary from person to person for a variety of reasons. For example, an athlete who is working out to add muscle or training for a triathlon needs more protein than a person who does less strenuous exercise. Despite these individualized protein needs, there are some broad recommendations that apply to most people.

There are two ways to estimate the amount of protein a person needs, both of which you may be familiar with. One is to recommend a certain amount of protein, in grams, based on body weight. The RDA, the amount that meets the needs of almost all healthy adults, is 0.8 grams of protein per kilogram of body weight (g/kg) per day. You can calculate your protein requirement by multiplying your body weight by 0.4, so a 200 lb. person would require about 80 g protein per day. (You can also use an online calculator, like this one)

Meeting this protein requirement isn’t very difficult. A four-ounce serving of meat contains about 30 grams of protein, an egg has 6 grams, and a cup of milk has 8 grams. Plants contain protein, too—whole grain bread and cereal has about 4 grams per serving, and one cup of cooked beans contains about 15 g. Getting enough protein is important, but there is little benefit to eating more protein than you need and excessive intake could cause health problems.

In general, most adults get enough protein but children, women who are pregnant, and older adults should make an extra effort to eat protein-rich foods. Vegetarians and vegans, especially athletes, need to carefully plan meals to get enough protein and the right balance of amino acids to meet health and performance requirements.

The other way to estimate protein needs is based on the number of calories you eat. According to the Institute of Medicine, the acceptable range for protein is between 10–35% of total calories. If you eat 2,000 calories each day, this would equal 50 to 175 grams of protein each day. For someone who weighs 200 lbs, this would be between 0.5 and 2.0 grams of protein per kilogram. Notice that the RDA fits within this range, which accounts for the protein requirements of nearly everyone, including people who have very high protein needs.

While the RDA is sufficient for most healthy people, even those who exercise regularly, it may be too low for athletes engaged in strenuous endurance or strength training. The protein requirement for endurance athletes, including runners, cyclists, and triathletes, is 1.2–1.4 g/kg per day. Athletes who are training to add muscle mass and strength—think football players in the offseason—need even more protein: 1.2–1.7 g/kg per day. This should meet both energy needs to fuel training sessions and provide adequate protein for muscle repair and growth.

For most of us, though, the focus should not be on eating more protein but to get our protein from healthy sources. For starters, several servings of protein-rich lean meat, eggs, and dairy as well as whole grains, legumes, and vegetables should meet protein needs. The emphasis should be on real food rather than processed foods with added protein. After all, no amount of granola bars with added protein will make you healthier!


Nutrition, exercise, and health information can be confusing. 
But it doesn't have to be that way.
What can I help you with?
 drbrianparr@gmail.com | http://twitter.com/drbrianparr