rock climbing courses

Are high protein diets needed for rock climbers?


Nutritional aids and gimmicks are commonplace in sports. Body builders and power lifters have in many cases been taken in by these and often only rely on information supplied by other body builders, supplement endorsers and magazine advertisements (Manore et al, 1993). These high protein diets have also been used by rock climbers aiming to achieve greater strength and power. It is not unusual for people involved in strength training to consume a high protein and low carbohydrate diet. Spitler et al in 1980 reported that male bodybuilders get 85% of there kcals from protein and these diets still seem to be popular with today's bodybuilders (Hickson and Wolinsky, 1989; Kleiner et al 1990 and 1989). In contrast to this endurance athletes have no long history of high protein diets (Lemon, 1995) In this article I am going the review protein and whether rock climbers, bodybuilders and power lifters need higher levels of protein above that of other active people.


Protein is made up of chains of amino acids linked through peptide bonds. The sequence (the primary structure) and the number of amino acids in the chain distinguish the type of protein made. The chain will form a folded, three-dimensional shape called the secondary structure; this is local folding into an alpha helix or beta-sheet. A tertiary structure (folding of the chain on its self) can be formed and if two or more of these join the quaternary structure if formed.


There are 20 amino acids 8 of which are essential to the diet as the body cannot synthesize these from other amino acids. These are listed in table 1. Amino acids are made out of hydrogen, carbon, oxygen and nitrogen which are arranged into a carboxylic group, amino group and a side chain and can take on different forms depending on which amino acids it is.


Table 1. Essential and non-essential amino acids

Essential amino acids Non-essential amino acids
Isoleucine (BCAA) Alanine
Leucine (BCAA) Aspartic acid
Valine (BCAA) Asparagine
Lysine Cysteine (C)
Histidine Glutamic acid
Methionine Glycine (C)
Threonine Proline (C)
Phenylalanine Serine (C)
Tryptophan Tyrosine (C)
Arginine (C)
Histidine (C)

BCAA- branched chain amino acids

C – Conditionally essential amino acids may be synthesized from other essential amino acids but may be needed in some situations e.g. histidine cannot be synthesized rapidly enough if there is none provided in the diet.


In animals protein is not just stored for energy requirements, that is all proteins in the body have a function other than storage of energy such as skeletal muscle, transport proteins in cell membranes, enzymes, hormones and pH buffers.


Protein is found in many food types and foods contain different amounts of the amino acids. A food that contains all of the essential amino acids is considered to be of high biological value, such as meats.


Table 2. Common foods and their protein values

Food type Protein content (grams of protein / ounce of food)
Breads 1.55 – 3.42
Cheese cake 1.5
Vanilla milk shake 0.98
Plain pancakes 2.10
Cereals (without milk)
Corn flakes 4.24
Froot loops 2.30
Fruit and fibre 2.99
Oatmeal 0.73
Puffed wheat 4.25
Rice krispies 1.86
Raisin bran 2.7 – 3.1
Special K 5.58
Hard cheeses 4.5 – 8.4
Cottage cheese 3.5 – 4.9
Fish 5.0 – 7.5
Shrimp 5.93
Tuna in water 8.38
Ground beef 7.0
Roast beef 8.1 – 9.0
Beef frankfurter 3.20
Cooked chicken 7.7- 9.3
Turkey frankfurter 4.05
Turkey ham 5.37
Cooked eggs 2.9 – 3.5
Milk 0.93 – 0.97
Yogurt 1.2 – 1.6
Green beans (cooked) 0.4 – 0.5
Navy beans 2.46
Corn 0.80
Lentils 2.56
Peas 1.5
Potatoes 0.5
Spinach 0.84
Tofu 2.93
Almonds 5.7
Spaghetti 1.0 – 1.4
Pizza with cheese 3.54
Pizza with cheese and pepperoni 5.94

Protein is first denatured (breaking of higher protein structures) by cooking then further broken down by enzymes in the stomach. They are then digested into single amino acids, which are then metabolised mainly in the liver, some amino acids are also metabolised in the muscles. The liver controls the releases of amino acids into the free amino acids pool in the blood and the tissues. Amino acids enter the free amino acid pool by ingested amino acids, protein break down or synthesis of non-essential amino acids via trans-amination in the liver. Amino acids are lost from the pool by secretion into the gut, the building of new proteins or by oxidation for energy and when it is made into carbohydrates or fat. Amino acids are lost from the body when the skin peals, in the urine, sweat and carbon when we breathe.


During exercise and recovery muscle protein turnover is increased because of a greater rate of muscle protein synthesis and breakdown (Biolo et al 1995). Muscle protein synthesis is more than doubled at 24 hours after exercise (MacDougal et al 1995) and breakdown is increased to 31% and 18% after 3 hours and 24 hours respectively after exercise (Phillips et al, 1997).


Under normal situations the body does not gain or lose protein. This means that amino acid oxidation should balance dietary protein (normally 70-100g of protein per day). Resistance exercise caused an increase in protein synthesis and protein turnover (Chesley et al, 1992; Marable et al, 1979; Yarasheski et al, 1993; Macdougal et al, 1995), this suggests that athletes, particularly those wanting to increase muscle mass need extra protein in there diet therefore athletes wanting to gain muscle size have a larger requirement of dietary protein. The protein needs of people taking part in strength training have been shown to be up to two times the needs of sedentary individuals (Lemon et al, 1992; Tarnopolsky et al, 1992). Protein requirements have been shown to be related to intensity and volume of training (Burke et al, 2001). As strength training is more intense than endurance we can assume that people evolved in this sort if training will need extra protein in their diets.


In general there is a consensus that protein intake should be slightly higher in active individuals than in the sedentary population (recommended protein intake for the sedentary population is 0.8g/kg/day). A protein intake of 2.0g per kilogram of body weight is required to maintain a positive nitrogen balance in strength athletes (Celejowa et al, 1970; Laritcheva et al, 1978). A study in 2001 by Burke et al showed that after 6 weeks of resistance training a group receiving Whey protein of 1.2g/kg of body weight increased their lean mass over the placebo group and knee extension torque increased over the control group (P < 0.05). Increases in 1-rep max tests may have been due to the learning effect as all the groups in this study displayed a significant increase from the start of the study to the end. There was no change 1 rep max for the bench press and squat strength. A similar value was set by Hargreaves (2000) and said that strength athletes should consume 1.2 - 1.6 grams of protein per kilogram of body weight, this value is higher than the recommended daily allowance, and even under extreme condition daily requirements are unlikely to exceed this slightly higher value (Gibala, 2000).


Figure 3. A graph showing how protein synthesis increases with exercise and protein intake.


Adapted from Tarnopolsky et al (1992).


When 2 grams of protein on top of the normal diet is ingested there is an increase in amino acid oxidation, which suggests that protein intake was exceeding muscle growth (Fern et al, 1991). As shown in Figure 3 Tarnopolsky reported that increasing protein intake two 2.4grams of protein per kilogram of body weight did not increase protein synthesis above that of 1.4g. kg-1 (Tarnopolsky et al, 1992). All this evidence suggest the theory that body builders do need to take large amounts of dietary protein above that of other individuals but there is a cut of point above which any more protein in the diet is metabolised. Because athletes have high-energy intakes they should be able to obtain all their protein needs from there normal diet and no dietary supplements are needed (Tipton, 2000).


Exercise has been shown to increase blood urea which is an end product of amino acid metabolism (Lemon, 1991) this suggests that protein requirement of endurance athletes are also elevated above that of sedentary individuals. A protein intake of 1.0g/kg-body weight has been suggested for people starting endurance activities (Gontzea, 1974). Many studies have indicated that a value of 1.2-1.4 g/kg/day should be used for endurance athletes (Brouns et al, 1989; Friedman and Lemon, 1989; Meredith et al, 1989; Tarnopolsky et al, 1988). These values are higher than the sedentary populations recommended daily allowance but slightly lower than strength athletes.


Amino acids may become substrates for gluconeogenesis, be used in the Kreb cycle or oxidised directly in the muscle to produce energy. Energy requirements for all types of exercise are from carbohydrates and lipids and for short term exercise the energy contribution from proteins and amino acids is small (Astrand, 1977). This may change during endurance events where carbohydrate stores are reduced forcing the body the rely more on proteins. Protein contribution for endurance events is still low at around 2 –5 %. Extra protein does not need to be ingested by power lifters for extra energy benefits. This may be the opposite in the case of endurance athletes. This could be due to increased amino acid oxidation during prolonged exercise and to replace damaged muscles, which can be increased if the exercise has a high eccentric component (Evans, 1991). It has been shown that amino acids can be lost due to the carbon skeletons been oxidised in the muscle or liver (Lemon et al, 1985; 1982) and training may also increase amino acid oxidation, studies on rats have shown that amino acid oxidation increased after 8 weeks of training (Dohm et al, 1977). The effects of exercise and diet are shown in figure 4.


Figure 4. A graph showing how exercise increases whole body leucine oxidation.

Adapted from Layman et al (1994).


To obtain maximum gains in muscle mass and to aid performance athletes should eat the type of food energy that is been utilised, this is carbohydrate, i.e. at least 50%. During resistance exercise skeletal muscle net protein balance increases but if the athlete is fasted protein breakdown will exceed anabolism (Gibala, 2000). A high protein diet has been shown to cause an increase in protein catabolism (Walberg et al, 1988). Athletes who are trying to increase there lean body mass such as wrestlers and bodybuilders may need to consume more protein to compensate for the protein breakdown caused by there low energy diets (Butterfield et al, 1992; Lemon, 1992). This problem would also be over come by eating a diet with sufficient carbohydrates so that the body will not need to rely on energy from protein. Glycogenolysis during resistance exercise is extremely high and a multiple sets of a single exercise can decrease muscle glycogen by 20 –40 % (Gibala, 2000) and during a mixture of endurance and strength exercise it can be as much as 88% (Montgomery, 1988). This means that carbohydrate ingestion is very important for both strength gains and endurance exercise. Eating carbohydrates will increase blood insulin (Rasmussen et al, 2000) and insulin is responsible for an increase of amino acids into the muscles (Biolo et al, 1995) so may help in muscle synthesis. Hargreaves (2000) suggests that diets of both endurance and bodybuilders should be high in carbohydrates but also contain a normal amount of protein (1.2 –1.6g/kg) to optimise muscle growth. This theory has been backed up by Zant et al (2002) who showed that diet rich in carbohydrates and fats did not affect strength performance in moderately trained males.


Muscle protein synthesis rates after strength training are stimulated with amino acid supplementation, which included essential and non-essential amino acids. (Tipton et al, 1999). The mechanisms by which this happens are not known but may be due to an increase in the amino acid supply to the muscle causing a higher delivery across the muscle membrane and supply amino acids and energy for protein synthesis (Zachwieja et al, 2000). It is also possible that that amino acid supplementation will decrease protein catabolism (Maclennan et al, 1988). It has been shown that infusion of a mixed amino acid solution in the post absorptive state stimulates mixed muscle protein synthesis (Bennet et al, 1990 and 1989; Biolo et al, 1997; Rasmussen et al, 2000; Zachwieja et al, 2000). There are some problems with these studies, Zachwieja et al (2000) used L[1-13C]leucine to evaluate the rate of muscle synthesis. Leucine is a branched chain amino acid that is normally metabolised in the muscle not the liver. In my opinion the uptake if L [1-13C]leucine is the study is not an indicator of increased muscle synthesis but just an indicator of normal protein metabolism. A similar study by Rasmussen et al (2000) over came this problem by using ring-2H5-phenylalanine to evaluate muscle protein uptake. Also none of these studies measured muscle size or muscle strength. All these studies have also only been short-term studies and the long-term effects are still to be established.


A build up of serotonin in the brain has been linked to fatigue during exercise. If branched chain amino acids (BCAA) reduced the uptake of the amino acid Tryptophan into the brain so less trypotophan was converted into serotonin it would be advantageous for athletes, particularly endurance type to consume BCAA during exercise. This has been shown to be the case but BCAA ingestion does not seem to benefit performance (Tipton et al, 2000; Vanhall et al, 1995).


There is a hormonal response to exercise and this has been shown to increase with protein supplementation (Chandler et al, 1994 and Kraemer et al, 1998) Results from studies looking at hormonal changes causing a alteration in muscle mass have been equivocal with some studies showing protein to have an effect (FiataroneSingh et al, 1999 and Meredith et al, 1992) and others showing no effect of protein supplementation (Cambell et al, 1995; Lemon, 1992; Tarnopolsky et al, 1992 and 1988). It has been claimed that amino acids can cause an increase in human growth hormone and insulin levels. Bucci et al (1990; 1992) gave body builders 40, 100, 170mg/kg-body weight of L-ornithine and no increase in insulin was found but there was a significant increase in growth hormone. Still this may not increase strength or lean body mass as there is little evidence linking growth hormone to strength or muscle mass gains and some studies showing no effect (Deyssig et al, 1993; Yarasheski et al, 1993 and 1995). This data suggests that body builders and power lifters will not get and hormonal benefits from high protein diets and therefore do not need to take extra protein above that of other active individual for endocrine responses.


The amounts of amino acids that the manufactures suggest are unlikely to increase muscle mass. Supplements on average contain only 4g per serving. Higher levels can cause mild and severe stomach cramps and diarrhoea. A high protein diet will cause higher Nitrogen excretion and extra water will be needed to allow this to happen. This loss of water could detriment sporting performance particularly in sports with high sweat loss.


In conclusion protein needs of active individuals are slightly increased above that of a sedentary individual. Endurance athletes also have and increased need for protein intake but not as much as strength training individuals. This increased intake does not support the fact that some athletes consume the majority of their energy intake from protein alone. The slightly raised protein needs can be gained from a normal diet consisting of 70% carbohydrates, 20% fats and 10% protein due the larger energy intake (Tipton, 2000). There seems to be little evidence for other advantages of protein and amino acid supplementation such as reducing fatigue and increase levels of anabolic hormones.


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