Strength training is a powerful ana-bolic stimulus and, if performed prop-erly, results in increased lean body mass(2). Specifically, the amount of myo-fibrillar protein, composed of actin andmyosin, is increased. Muscular tissueis made of protein which is synthesizedfrom amino acids. The amino acids arederived from the digestion of proteinfoods. Therefore, eating more proteinfoods provides more building blocks forthe synthesis of new muscular tissue (2,6). After all, during intense weight lift-ing, the muscle fibers are damaged (thisis why you’re sore after a workout), andthey must be repaired(1). Musculargrowth occurs by over-compensationduring the repair process. The harderyou weight train the more damage youdo to your muscles (which stimulatesgrowth), and the more protein you needto repair that damage. While strengthathletes have known this for years, manynutritionists assert that excess proteinwill be stored as fat or glycogen. Toreconcile these views, we should realizethat most studies which fail to demon-strate that exercise increases protein re-quirements use subjects who are nottraining intensely enough to stimulateincreases in lean body mass.
To extract several examples fromthe scientific literature: In a group of 10weight lifters exercising intensely andconsuming 2 g/kg/day (0.9g/pound/day)protein, 4 were in negative nitrogen bal-ance (4). In another study, a protein in-take of 2.8 g/kg/day (1.3 g/pound/day)was found to result in higher nitrogenbalance and greater muscular gains thanan intake of 1.4 g/kg/day (0.64 g/pound/day) (7). When weight lifters increasedtheir protein intake from 2.2 to 3.5 g/kg/day (1.0 to 1.6 g/pound/day) they in-creased in strength and lean mass (5).A protein intake of 2.6 g/kg/day (1.2 g/pound/day) was found to producegreater nitrogen retention than 1 g/kg/day (0.45 g/pound/day) (8,9). Takentogether, these results suggest that a pro-tein intake of 2 g/kg/day (0.9 g/pound/day) is inadequate for many athletes andthat as much as 3.5 g/kg/day (1.6 g/pound/day) works better for at leastsome hard training athletes. Anotherreason athletes require more protein thansedentary people is that amino acidsare used as fuel during exercise.After the body uses up its glyco-gen stores, it begins to burnamino acids (the buildingblocks of protein) and fatfor energy. In the liver,amino acids with three ormore carbon atoms canbe converted into glu-cose via a process called“gluconeogenesis.”
The branched chainamino acids (BCAAs) leucine, isoleucine,and valine can be burned for energy di-rectly in the muscle.This becomes significant duringhigh intensity endurance exercise. Un-der conditions of prolonged enduranceexercise (a 10-mile run, for example),the oxidation of amino acids can ap-proach recomended daily protein require-ments, and dietary amino acid needscould be elevated substantially (2, 10).In contrast, studies involving low inten-sity exercise actually indicate decreasedprotein need as the athlete adapts to thetraining regimen.Oftentimes, an athlete experiences adecrease in red blood cell count and se-rum iron levels during the early phase oftraining (6). This condition, known assports anemia, could be due to the factthat aerobic training causes an increasein myoglobin ( an oxygen carrying pro-tein) and cytochrome content of muscletissue, and the protein and iron requiredfor their formation could be obtainedfrom destruction of red blood cells (6,17). In other words, myoglobin may beincreased at the expense of hemoglobinif protein intake is inadequate. Further-more, skeletal muscle fibers are damagedduring intense exercise training, and thisdamage must be repaired during the re-covery period following exercise.
If di-etary protein intake is inadequate, thebody will draw on red blood cells, he-moglobin, and plasma proteins as asource of protein to repair the muscles(17).Increased nitrogen excretion (inurine and sweat) is commonly observedafter exercise, suggesting that protein isbeing used as an energy substrate to fuelactivity (1). Nearly all studies which in-clude nitrogen loss through sweatingfind subjects to be in negative nitrogenbalance during endurance activities.During prolonged exercise blood glucoselevels drop, eliciting a release of gluca-gon from the pancreas. This hormonemobilizes amino acids from muscle tissue to serve as substrates for glucosesynthesis in the liver. Dohm and co-workers (10) found an increase in uri-nary urea excretion (waste productsfrom protein catabolism) during the dayfollowing a 10 to 12 mile run by malerunners. This result indicates an increasein protein catabolism induced by endur-ance exercise. The amount of proteinmetabolized was calculated to be 57grams, enough to supply 18% of the en-ergy expended during the run. The au-thors suggested that protein was catabo-lized, possibly from skeletal muscle, toprovide precursors for glucose synthe-sis in the liver.
In summary, the short term stud-ies indicate that endurance exercise iscatabolic in nature, leading to an acuteincrease in protein catabolism. Somelong term studies suggest an adaptiveresponse to endurance training wherebythe proteins are utilized more efficiently(1). Other experts suggest that pro-tein requirements of trained athletesremain elevated after adaptation (11,12, 13). For example, 57 grams ofprotein— equivalent to the RDA for a158 pound man – may be catabolized asfuel during a 10-12 mile run (10). Ap-parently, the increased efficiency of pro-tein utilization which occurs as an adap-tive response to endurance training is notsufficient to accommodate the demandsof intense or prolonged endurance exer-cise.Of course, these arguments shouldnot discourage strength athletes from en-gaging in aerobic exercise. Aerobic ex-ercise is required to condition the car-diovascular system and maintain overallhealth and is very effective at burningfat. Athletes interested in increasingmuscular mass should still participate inaerobic exercise but eat enough addi-tional protein and calories to compen-sate for the energy expense.Lemon (2) states, “Although thecurrent recommended dietary allowancedoes not recognize that protein/aminoacid needs are higher in strength athletes,there is a substantial amount of experi-mental support to the contrary…If highprotein/amino acid diets are advanta-geous, it may be due to increased aminoacid availability and the enhanced ana-bolic stimulus of heavy resistance exer-cise.”
The athlete should bear in mindthe importance of adequate energy in-take. For growth to occur, adequateprotein and calories must be consumedto maintain the body as well as provideenough building blocks for new muscu-lar tissue.Since protein needs vary dependingon exercise type, intensity, frequency,duration, environment, and level of con-ditioning of the athlete (14), it is impos-sible to make exact recommendations foran individual athlete. It is possible, how-ever, to extract some minimum guide-lines from the literature. The generaltrend, (among intensely training athletes)seems to be increasing protein intakeincreases nitrogen balance and muscu-lar gains, at least to a level of 3.5 g/kg/day (1.6 g/pound/day). Encouragingly,protein supplements also seem to be ef-fective in improving gains in musclemass over that resulting from trainingalone (15).The published studies generally usesubjects engaged in either strength train-ing or endurance exercise, but not both.Many professional bodybuilders performtwo hours of intense weight lifting plustwo hours of aerobic conditioning perday (or even more), while at the sametime consuming a calorie restricted diet.Rather than being exceptional, we dealwith many athletes following such a regi-men as they prepare for competition.These athletes undoubtedly have excep-tional protein requirements.
On TheParrillo Perfromance Nutrition Pro-gram, we recommend that bodybuild-ers consume 1.5 grams of protein a dayper pound of body weight. One gramper pound of body weight should comefrom lean proteins, with the remaining.5 gram per pound of body weight com-ing from starchy and fibrous carbs.We’ve seen bodybuilders greatly improvetheir physiques by following these guide-lines.If you don’t consume enough pro-tein, your rate of muscular growth willbe retarded. To help you meet yourprotein needs, we have developed Hi-Protein Powder. Each scoop provides20 grams of ultra quality protein.People consuming a high proteindiet should be sure to drink plenty ofwater and to get enough calcium. Pro-tein metabolism generates ammonia,which is converted to urea and excretedin the urine and sweat. Drinking plentyof water aids the kidneys in removingthis nitrogenous waste and dilutes cal-cium salts which could form precipitates(kidney stones). Notably, there is no evi-dence suggesting that strength athletesconsuming a high protein diet have anincreased incidence of kidney disease.The data suggesting that a high proteindiet contributes to the progressive na-ture of kidney disease come from peoplewith pre-existing kidney problems (2).Many studies have demonstrated a posi-tive correlation between protein intakeand calcium excretion (16). Results areequivocal regarding protein intake andcalcium absorption. Some studies showthat protein improves calcium absorp-tion while others show the opposite.Calcium balance can be maintained dur-ing high protein diets by assuring ad-equate calcium and phosphorus intake(at least the RDA, 800-1200 mg/day).Each of our Mineral-Electrolyte tabletsprovide 250 mg calcium and 250 mgphosphorus.
1. Hickson JF and Wolinsky I. Humanprotein intake and metabolism in exer-cise and sport. In: Nutrition in Exerciseand Sport, eds. Hickson JF and WolinskyI, p. 5-36. CRC Press, 1989.
2. Lemon PWR. Protein and Amino AcidNeeds of the Strength Athlete. Interna-tional Journal of Sport Nutrition 1: 127-145, 1991.
3. Lemon PWR. Protein and exercise:update 1987. Med Sci Sports Exercise19: S179-A190, 1987.
4. Celejowa I and Homa M. Food in-take, nitrogen, and energy balance inPolish weight lifters during trainingcamp. Nutr Metab 12:259-274, 1970.
5. Dragen GI, Vasiliu A. Georgescu E.Effect of increased supply of protein onelite weight lifters. In: Milk Proteins,eds. Gasesloot TE and Tinbergen BJ, p.99-103. The Netherlands: Wageningen,1985.
6. Haymes E. Proteins, Vitamins, andIron. In: Ergogenic Aids in Sport, ed.Williams MH, p. 27-55. Human Kinet-ics Publishers, 1983.Protein: Superfood For Bodybuilders, Part II
7. Consolazio I, Nelson RA, MatoushLO, Harding RS, and Canham. Nitro-gen excretion in sweat and its relation tonitrogen balance experiments. J. Nutr.79: 399-406, 1963.
8. Lemon PWR, MacDougall JD,Tarnopolsky MA, and Atkinson SA. Ef-fect of dietary protein and bodybuildingexercise on muscle mass and strengthgains. (abstract) Can. J. Sports Sci.15: 14’s 1990.
9. Tarnopolsky MA, Lemon PWR,MacDougall JD, and Atkinson SA. Ef-fect of body building exercise on pro-tein requirements. (abstract) Can. J.Sports Sci. 15: 22’s, 1990.
10. Dohm GL, Williams RT, KasperekGJ, and Van Rij AM. Increased excre-tion of urea and N-methylhistidine byrats and humans after a bout of exer-cise. J Appl Physiol: Respirat EnvironExercise Physiol 52: 27,1982.
11. Friedman JE and Lemon PWR. Ef-fect of chronic endurance exercise onretention of dietary protein. Int J SportsMed 10: 118-123, 1989.
12. Tarnopolsky MA, MacDougall JD,and Atkinson SA.Influence of protein intake and trainingstatus on nitrogen balance and lean mass.J Appl Physiol 64: 187-193, 1988.
13. Lemon PWR. Influence of dietaryprotein and total energy intake onstrength improvement. Sports Sci Exch2, 1989.
14. Houck J and Slavin J. Protein nutri-tion for the athlete. In: Sports Nutritionfor the 90’s, eds. Berning JR and SteenSN, p. 1-14. Aspen Publishers, 1991.
15. Frontera WR, Meredith CN, andEvans WJ. Dietary effects on musclestrength gain and hypertrophy duringheavy resistance training in older men.(abstract) Can. J. Sports Sci. 13: 13P,1988.
16. Wapnir RA. Protein nutrition andmineral absorption. CRC Press, 1990.Chapter 5: Calcium, magnesium andphosphorus absorption, nutritional sta-tus and effect of proteins, p. 77-98.
17. Sherman and Kramer, Iron Nutritionand Exercise, in: Nutrition in Exerciseand Sport, eds. Hickson and Wolinsky,CRC Press, 1989, p. 291-308.