Protein Power

by DR. Aaron Keith

Protein plays three critical roles for cyclists.  First, it is the main structural component of muscles.  Second, the enzymes that are responsible for producing the energy necessary to power muscles are proteins.  Third, protein can supply up to 15 % of the energy used during long workouts.

While cyclists generally get enough protein in their diet, some of them get it from the wrong sources, and at the wrong times.  Few cyclists recognize and take full advantage of the performance-boosting benefits of consuming protein both during and after practices, workouts, and games or competitions.

How much protein you need each day depends on your size and the amount of exercise you do.  The bigger you are and the more you exercise, the more protein you need.  The average sedentary adult should consume about 1 gram of protein for every 3 pounds of body weight each day.  Athletes in moderate training should consume 1 gram of protein for every two pounds of body weight.  Athletes in heavy training can consume 1 gram of protein per pound of body weight.  For all athletes, protein should account for at least 15 percent of calories consumed, whereas carbohydrates should account for 60 percent and fat the other 25. Note that protein and carbohydrate yield about 4 cal/gram of energy while fats yield about 9 cal/gram.

Improving Athletic Performance

Protein’s role in improving exercise performance is becoming increasingly recognized.  In the past, sports nutrition research has focused on the benefits of carbohydrate and fluid supplementation during exercise.  It has been well established that fluid replenishment can improve temperature regulation and reduce cardiovascular stress.  Similarly, carbohydrate supplementation has been shown to delay the onset of fatigue.  This research established the scientific underpinnings for the ideal composition of a sports drink, which includes sodium, potassium, and 6-8% carbohydrate.  This has been the standard for almost 25 years.

However, research is now showing that protein can provide five additional benefits, when added to a carbohydrate/electrolyte sport drink.  Today, there is strong evidence that protein, in the proper ratio with carbohydrate, should be considered an essential ingredient in an effective sports drink.

1. Protein improves muscle energy dynamics 

Ingesting carbohydrate during exercise delays fatigue by increasing the amount of energy that is supplied by blood glucose and thereby slowing the rate of muscle glycogen depletion.  The hormone insulin is responsible for delivering carbohydrate to the muscle cell.  Insulin is released by the pancreas automatically in response to increasing glucose levels in the blood.  But, protein also stimulates insulin release.  When a small amount of protein is consumed with carbohydrate, there is a stronger insulin response and glucose is delivered to the working muscles more quickly, resulting in greater glycogen conservation and endurance.  But the amount of protein is important.  When too much protein is consumed during exercise, the stomach empties more slowly.  The ideal ratio of carbohydrate to protein in a sports drink is 4:1.  In this amount, protein has no effect on gastric (stomach) emptying.  In a university study, a sports drink containing carbohydrate and protein in a 4:1 ratio  (product used was Accelerade) increased endurance by 24% as compared to a conventional sports drink without protein and by 57% as compared to water.

2. Protein blunts rise in stress hormones

While most of the effects of long, hard workouts are positive, prolonged exercise results in the release of the stress hormone cortisol, which breaks down proteins for use as energy, leading to post-exercise soreness.  However, when blood insulin levels are kept high, cortisol levels remain low.  By stimulating higher blood insulin levels, a sports drink containing carbohydrate and protein reduces cortisol release more than conventional sports drinks and thereby reduces protein breakdown.

3. Protein delays fatigue

Protein may offer two advantages in helping delay fatigue during exercise.  The primary cause of fatigue has been shown to be depletion of muscle glycogen stores.  By stimulating insulin, protein helps preserve muscle glycogen stores.  In addition, protein may also affect other factors that play a role in the development of central nervous system fatigue (or “central fatigue”), which is associated with the breakdown of muscle proteins for fuel when carbohydrate fuel runs low.  By reducing the breakdown of    muscle proteins for energy, protein consumed during exercise could delay central fatigue, as well.

4. Protein maintains muscle protein

During exercise, muscle protein breakdown increases.  This is because protein supplies up to 15 percent of energy needs during the latter portions of long workouts.  This leads to a significant net muscle protein loss and a reduced ability to rebuild muscle protein after workouts.  Consuming a sports drink that contains protein spares muscle protein during exercise and speeds muscle recovery after exercise.

5. Protein may protect the immune system

Hard exercise can suppress the immune system and increase an athlete’s risk of viral infection.  The amino acid glutamine is believed to counteract exercise-induced immune system suppression.  In one study, 200 runners and rowers consumed either a glutamine-containing drink or placebo drink.  The percentage of athletes who reports no infections was 81% in the glutamine group and 49% in the placebo drink. Whey protein has a high concentration of glutamine.

Protein and Recovery

Following exercise, protein plays a powerful role in rebuilding and reenergizing muscle cells, especially when combined with carbohydrate.  As a general rule, within the first hour after a workout, try to consume 1 gram of protein for every 8 pounds of body weight.  In addition, consume about 4 grams of carbohydrate for every 1 gram of protein.

Research has shown that consuming carbohydrate and protein together within an hour of completing exercise results in faster muscle glycogen resynthesis and faster muscle protein building than when carbohydrate is taken alone, or when both are taken more than a half hour post-exercise.  In one study, a carbohydrate-protein recovery drink (Endurox R4) decreased post-exercise muscle damage, increased post-exercise muscle glycogen synthesis, and extended next-workout endurance more than a sports drink containing carbohydrate and no protein.

Protein Guidelines

Protein, particularly when consumed in the proper ratio with carbohydrate, can give cyclists an edge.  Here are some simple protein guidelines that I use to help my recovery from cycling. 

Every Day:  Protein should represent 15% of total calories.  For me I tend to shift my protein intake to 20-25% during the winter months while I am doing more weight training rather than aerobic endurance athletics.  

During Exercise:  10-20 grams (40-80 calories) of protein per hour in combination with 40-80 grams (160-320 calories)of carbohydrate (a sports drink such as Accelerade)

After Exercise:  0.5 gram (2 calories) of carbohydrate plus 0.125 gram (0.5 calories) of protein per pound of body weight.

Thoughts to ponder.   I realize that most people do not think in terms of grams or have a food scale around to measure all their foods.  When thinking about proper portions of protein, use the palm of your hand.  Don’t eat it, think chicken, beef, pork or fish or eggs.  The palm represents approximately the amount of protein that should be eaten at each meal.  Everyone is different in the way their body responds to food, supplements, etc.  So, experiment with supplements during our practice rides.   If someone you ride with has a sports drink they find beneficial, try it and monitor your response.  Also, try and monitor your intake of plain water versus sports drinks as well as energy bars and other energy supplements such as Gu .

This article is adapted from Edmund Burk, Ph.D. He was an exercise physiologist, who authored many books on cycling and muscle recovery.