Experience From - Dr. Bill Miser , Karl King ,

Dr. Bill Miser

Lately, I have received several questions related to protein, plus some excellent comments from the IUS-L on (1) "Fuel Selection", (2) the 40-30-30 diet, and (3) how to achieve optimal protein nutrition balance for energy demands during prolonged endurance activities. Perhaps this somewhat longer treatise(xp) will summarize some of my principle answers for the kind of dietary application that may result in optimal performance, especially in the area of specific dietary protein protocols. The correct exact use for dietary protein to support prolonged endurance activity is widely debated among sportscientists. What follows is my opinion based on published research and observations/measurements I have recorded.

Mistakes can be made with dietary intake of carbohydrates and fat, but the margin for error is typically less for PROTEIN since it is the basis for all body structures and functions. Radioisotope techniques have confirmed that 98% of every cell in the body is replaced within 1 year's time! In any 6 months time period, all muscle cells, all blood cells, all enzymes, and all gene cells are completely replaced. Over half the dry weight of the human body is protein. Skeletal muscles are 65% protein, hemoglobin is 20% protein, and brain cells are 10% protein. Muscle mitochondria, where ATP/CP metabolizes energy for movement in time and space, over 2000 enzymes made up of globular proteins spark the biochemistry of performance. The solid structures of the body such as skin, nails, bone, hair, ligaments, and tendons are made from the structural class of proteins. If the balance of dietary protein is tipped toward too much or too little, either way, the results are devastating to both training and performance. How do I know if my dietary intake is either insufficient or too much?


  1. Muscle Mass will deteriorate resulting in weight loss or girth size loss.
  2. Premature fatigue occurs during endurance training.
  3. Heart rate will be high during interval training.
  4. Lack of motivation to train will prevail before workouts involving intensity of effort.

  1. Excess Amino Acids are converted to toxic tissue ammonia, which is then deaminated to form urea.
  2. Urea is excreted by way of kidneys and sweat glands.
  3. Excess Urea in kidneys will cause low back pain.
  4. Excess Urea will cause "feelings" of Malaise, discomfort, lack-lustre,and apathy.
  5. Blood Urea Nitrogen(BUN) will measure in normal health between 10-14 mg/dl. If BUN is over 21 mg/dl then you are either severely dehydrated or you are eating too much protein.
  6. Dietary physiological correction may take as long as 4 weeks to "balance" all the body systems from either excessive or lack of quality protein in the diet.
  7. UREA measured(BUN) in Sweat Loss has been shown to be elevated in endurance athletes who consume low carbohydrate diets.(Lemon et al., 1981) The UREA(BUN) also tends to be higher when muscle glycogen stores are depleted near the end of an endurance session. Both may be prime indicators for using a 60-20-20 or 70-15-15 Cho-Pro-Fat dietary protocols for pre-training nutrition, and are definitively do not in favor the use of a 40-30-30 diet. When Blood Urea Nitrogen(BUN) is high, lean muscle mass cannibalization is high, not the optimal direction for progressive training gains. A high serum BUN is a clear indication of negative training digression.

Make no mistake about this important dietary note...You are what you eat in a very physical sense. Recently some associates of mine in Great Britain had there soft tissue structures analyzed by Magnetic Resonance Imaging(MRI). The vegetarians, in this study, showed minute amounts of body fat stores located in subcutaneous areas, while the meat eaters tended toward intra-muscular "marbling" similar to the dietary red meat they had included in their daily diet. Body fat is dead weight for the endurance athlete especially on hilly terrain and specifically during longer bouts requiring prolonged effort. When the demand for strength movement in terms of torque generated over shorter periods of time is great, the demand for muscle fiber girth and larger amounts of dietary protein tend to be greater. Nitrogen Balance studies have determined actual protein needs for 3 types of exercise demand:


  • Strength Sports
    Weight lifting-Gymnastics
    Track and Field Throwers.......2.0 grams/kg.

  • Sprint Sports
    Boxing, Karate, Judo
    Swimming, Track................1.7 grams/kg.

  • Endurance Sports
    Triathlon, Marathon
    Ultramarathon, cycling
    Cross Country Skiing,
    Mountain Biking................1.4 grams/kg.

    Since the QUALITY of dietary protein is only as good as its weakest amino acid link, the FDA has rated dietary proteins as based on the Predicted Digestibility Corrected Amino Acid Scale(PDCAAS). The highest score any source of protein can achieve is 1.00 in terms of this rating scale and the effects of protein for human metabolic functions. What then are the best sources of 1.0 PDCAAS rated protein?

    PROTEIN SOURCE                  PDCAAS SCORE
    Soy Protein                         1.00
    Whey Protein                        1.00
    Egg White Protein                   1.00
    Beef                                 .92
    Rolled Oats                          .57
    Peanut Meal                          .52
    Rice Flour                           .47
    Corn Flour                           .42
    Wheat Gluten                         .25
    Combinations                         **see below
    **For vegetarian athletes, combining grains, legumes, and vegetables within a 24-hour window, assuming the quantity is sufficient, will ensure a 1.0 PDCAAS equivalence.

    Mass studies of dietary intake in countries where lean muscle mass balances are maintained, those diets contained 12% protein from total caloric intake. Even the lowly potato contains 11% of its total caloric content as dietary protein, so it is not too difficult to get 12-15% of your calories from food sources, but to get the best dietary amino acid profile, I would offer the following suggestions*:

    1. Use only 1.0 PDCAAS protein food sources.
    2. Divide protein intake equally in each meal.
    3. During training, use an energy drink that contains the Branched Chain Amino Acids(BCAA) or some form of complete protein.
    4. Supplement at least 1-2 per day a Soy, Whey, or Egg-White powdered protein source.(90%+ protein by weight)
    5. Estimate Protein intake by dividing total body weight by 2.2(kilogram weight), then multiply kilogram weight by 1.4...That will give you how much protein in grams per day that you will need to maintain a positive Nitrogen balance.

    *A FOOTNOTE... If anyone on the list is confused by this hopefully "Practical Application" for dietary protein, please do not hesitate to contact me and I will post answers back to the list as appropriate as I am able. Let all be aware that sportscience still is disagreed upon this issue. In 1997, I did a research project among 8 randomly selected "experts" in the sportscience field, all with M.S. and Ph.D. degrees....there were dramatic differences of opinion and rationale for the dietary protein requirements they use to counsel their athletes. I do hope this will at least assist some of you with the dietary design of your fuels-of-choice, especially the most important one, the right amount of the best dietary protein.

    Karl King

    The vast majority of protein supplement powders are a huge rip-off. The only redeeming feature is very low fat content compared to a double cheeseburger.

    For protein away from the run, try real food. You can get more than enough protein from eggs, chicken, fish, etc. The price is much lower, and you get some vitamins and minerals to boot. Many of the "engineered" body builder foods are inexpensive carbohydrates mixed with low to moderate grade protein. They are a great way to sell carbohydrate at protein prices.

    During a run, I find that whey protein is the easiest to digest.

    In short, I think it makes sense to use a specialized product during a run, but to eat normal food otherwise.