Curtin University
School of Physiotherapy

Strength gains are enhanced by nutritional supplements!

Proposition for Debate - by Tania Ashfield and Hilde Gjellesvik

Contents

Statement of the Topic

Strength gains are enhanced by nutritional supplements!

Affirmative Argument by Tania Ashfield

Background Knowledge

Muscle strength enhances power, endurance and protects against injury and as such is an integral part of athletic training. To achieve the competitive edge, many athletes use ergogenic aids aiming to increase lean body mass. One category of ergogenic aids are nutritional supplements.

Synthesis of muscle tissue requires energy to perform the exercise that will stimulate muscle growth and energy to build muscle. Therefore adequate dietary energy and protein are key constituents for muscle growth. It is necessary to consider the role of the basic requirements for muscle growth prior to investigating the types of nutritional supplements used to increase lean body mass.

Role of Carbohydrates (CHO)

Carbohydrates exist in the form of monosaccharides, olidosaccharides (double sugars) and polysaccharides. Sources of polysaccharides are either plants providing starch and cellulose or animals providing glycogen (McArdle et al. 1986).

Functions of carbohydrates
CHO in exercise

During intense exercise, CHO provides an anaerobic energy source in the period of early exercise and fulfills the shortfall of the aerobic energy system. With increased intensity and duration of exercise there is a resultant increase in CHO requirements.

Dietary deficiency of CHO results in rapid depletion of muscle and liver glycogen stores and decreased performance in intense short term exercise.

Fatigue during prolonged exercise has been directly related to the onset of muscle glycogen depletion or hypoglycaemia (Kleiner 1997, Tsintzas and Williams 1998).

Recommendations for body builders

Role of Protein

Protein is the basic building material for muscle tissue and is formed by amino acids linked by peptide bonds form proteins containing an amino acid (AA) radical NH2 and an organic acid COOH (McArdle et al. 1986).

Amino acids are classified as essential and non essential. Essential AAs are those that are not synthesised in the body and include isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Other AAs are synthesised in the body at a rate required for N growth and development. Complete proteins are contained in meat. In comparison plant proteins are termed incomplete.

Protein makes up 12 - 15% of body weight. In contrast to CHO, there are no stores of protein (McArdle et al. 1986).

Functions of protein

Protein has a primary anabolic function and is essential for the contractile function of muscle: actin, myosin are contractile proteins. 2 - 5% of energy requirements are provided by protein in normal individuals (McArdle et al. 1986).

Resistance training is a potent stimulus for muscle growth. Muscle protein synthesis rises markedly after endurance and resistance type exercise and conversely, disuse of muscle results in catabolism of protein for energy requirements.

The RDA of protein for the normally active individual is:

These quantities support normal growth and development (Williams 1993).

Recommendations for body builders

Role of Vitamins

Vitamins A,D,E and K are fat soluble vitamins while water soluble vitamins include B6, B1, B2, niacin, pantothenic acid, biotin, folic acid, B12, C and ascorbic acid.

B complex vitamins are of interest to body builders for their important function in energy yielding reactions of fat and CHO metabolism (Williams 1993).

Role of Creatine

Creatine is a nitrogen containing substance formed in the liver, kidneys and pancreas by AAs and meat and fish supply a dietary source. Normal daily requirements (of a 70kg male) are 2g. 1.1kg of raw meat supplies 5g of creatine.

95 per cent of body creatine is stored in muscle tissue, with Type II fibres having a larger store than Type I fibres. Muscle creatine used in contraction is replaced by supplies by the blood (Engelhardt et al. 1997).

Creatine rapidly bonds with phosphate to form high energy compound stored in muscle (CP). It is necessary for formation of CP in the mitochondria and resynthesis of ADP to ATP.

Types of Supplements and Benefits

Carbohydrates

The aims of carbohydrate supplementation are to supply an immediate source of energy to delay the onset of fatigue. Supplementation in the form of sport drinks also acts to maintain fluid levels therefore preventing heat illness and decline in performance due to dehydration (Tsintzas and Williams 1998).

Onset of fatigue coincides with glycogen depletion in type I fibres. CHO supplementation results in hyperglycaemia and hyperinsulinaemia to increase uptake of CHO to muscle cells. Availability of glucose to muscle cells delays glycogenolysis and depletion of muscle glycogen stores. CHO supplements have been proven to increase the time to fatigue during prolonged submaximal efforts and improve high intensity efforts after prolonged submaximal exercise (Tsintzas and Williams 1998).

Sports drinks are supported by research to be useful if exercise particularly if activity is of a duration longer than one hour (Williams 1993). CHO in the form of a seven per cent solution pre game and at half time has been shown to have a resultant 39 per cent decrease in muscle glycogen depletion in soccer players (Tsintzas and Williams 1998). Ingestion of a bolus of fluid prior to sport of volume five to eight mLs/kg body weight and a further 2mL/kg body weight every subsequent 15 to 20 minutes has been found to stimulate gastric emptying, increase blood glucose levels and decrease muscle glycogen depletion during the first hour of exercise (Tsintzas and Williams 1998).

Pre exercise "loading" of CHO provides maximal muscle glycogen stores prior to exercise. Ingestion of CHO two hours prior to exercise will increase uptake from blood sugars and spare glycogen stores (Tsintzas and Williams 1998). Maintenance of CHO levels also results in protein sparing so that the amino acid chains are available to synthesise muscle rather than a source of energy (McKardle et al. 1994).

Tsintzas and Williams (1998) summarise the ergogenic effects of CHO ingestion during exercise as:

  1. "the restoration of euglycaemia and increased oxidation of blood glucose late in exercise at a time when muscle glycogen contribution to energy metabolism is diminished" and
  2. "a decreased rate of muscle glycogen utilisation, which would delay its depletion and hence the point of fatigue".

Protein

Protein supplements are available in the form of powder or canned liquid meals. Availability of protein stimulates the release of insulin and growth hormone providing optimal conditions for muscle synthesis after exercise. Ingestion of AAs regulates human growth hormone (HGH) and insulin secretion resulting in decreased body fat, increased lean body mass and increased strength over five weeks (Williams 1993).

While a balanced diet will provide adequate protein, supplementation of protein fulfills the short fall of an inadequate diet and is a convenient source of protein for the busy athlete.

Anabolic hormones

The anabolic effect of resistance training is influenced by levels of serum testosterone, HGH and insulin. Exogenous sources reported to have beneficial effects on muscle synthesis (Williams 1993).

Creatine

Increased oral intake of creatine results in increased blood creatine concentration and increased uptake by the muscle cells. Oral supplements of 20 - 25g / day have been shown to result in increased creatine content in muscle by 20 to 25 per cent, increase muscle torque and improve athletic performance. Untrained individuals are able to achieve creatine levels equal to those of trained athletes and trained athletes have exhibited improved endurance performance after creatine supplementation (Williams 1993 and Engelhardt et al. 1997).

Vitamins

Antioxidant vitamins (C,E and B carotene) may protect against muscle damage caused by intense exercise and production of free radicals (Williams 1993).

Carnitine

Carnitine is a vitamin like substance found in food, especially meat. It facilitates transfer of long chain free fatty acids into the mitochondria and therefore improve aerobic endurance. In the strength athlete, it is though to facilitate the loss of body fat (Williams 1993).

When do Nutritional Supplements Enhance Strength Gains?

References

Engelhardt M, Neumann G, Berbalk A and Reuter I (1998)
Creatine supplementation in endurance sports. Medicine and Science in Sports and Exercise 30: 1123 - 1129.
Kleiner SM (1997)
Nutrition for muscle builders. Physician and Sports Medicine 25: 146 -146.
McArdle WD, Katch FI and Katch VL (1986)
Exercise Physiology: Energy, Nutrition and Human Performance. (2nd ed.) Philadelphia: Lea & Febiger.
Tsintzas K and Williams C (1998)
Human muscle glycogen metabolism durine exercise: effect of carbohydrate supplementation. Sports Medicine 25: 7 - 23.
Williams M (1993)
Nuritional supplements for strength trained athletes. Sports Science Exchange 6.

Negative Argument by Hilde Gjellesvik

Introduction

It is believed that good muscle strength will enhance performance and prevent injuries. Increased strength is especially important for athletes involved in sports where increased lean body mass is a determinant ofsuccess. While it is true that good nutrition is essential for weightlifters to enhance strength and power, for others improving stability (football), and for bodybuilders to enhancing their aesthetic appearance (Tucker 1987), is supplementation necessary?

The most obvious effect of strength training is muscular hypertrophy. For athletes with genetic limitations in hormonal status (especially testosterone) exogenous anabolic/androgenic steroids are used to maximise muscle growth (Williams 1994). There is an increasing focus on nutrient supplementation as an alternative ergogenic mean to enhance muscular mass and strength (Coward 1992 and Kleiner 1991).

Surveys of nutritional supplements (hundreds of products) are being published in health and bodybuilding magazines (Ironman, Muscle and fitness), claiming to enhance muscle growth although in many cases the scientific data are very limited or non-existent.

Facts about Nutritional Supplements

Nutritional supports for muscle growth are carbohydrates, fat, protein, vitamins, minerals, and water provides energy. They also regulate metabolic processes, and are all of importance for strength trained athletes trying to increase muscle mass and strength.

Protein is an essential nutrient for energy and support of muscle growth. It is the major constituent of muscle other than water. Adequate dietary protein intake is a key element for muscle growth.

So how much energy do athletes need?

According to Lemon (1991) daily energy intake for athletes maintaining their body weight should be equal to energy expenditure. For athletes trying to stimulate muscle development it is not known exactly how many additional megajoules (1MJ= 238 kcal) of energy are necessary to form one kilogram (kg) of muscle tissue. Nor in what form this energy should be consumed. Estimations range from 21 to 33,6 MJ/kg of muscle. Williams (1992), Bartels et al (1989) claim that an additional intake of 2.2MJ (500 kcal) daily is reasonable if the athlete is attempting to gain 1lb of muscle mass per week.

How much protein do athletes need?

Recommended dietary allowance (RDA) for protein is 0.8 g/kg body weight per day for persons 19 and above (0.9 for 15-18 and 1.0 for 11-14). Athletes involved in intense strength training programs have higher protein requirements (Lemon 1991, Lemon et al 1992, Tarnopolsky et al 1992). For them it recommended a protein RDA of 1.5-2.0 g/kg.

How to get the additional energy and protein?

Lemon and Mullin (1980) suggest that a balanced diet with carbohydrates such as bread, cereals, rice and pasta is sufficient to get the additional energy needed. Other healthful protein sources are lean meat, fish, skim milk, and legumes complemented with grains.

Protein supplements targeted to strength athletes are marketed as powdered protein, canned liquid meals high in protein has its protein content derived from food sources as milk, egg, or soy protein and have no advantages over natural sources. According to Williams (1993) there is no reliable research supporting these protein supplements when compared to natural protein sources. Commercial supplements can be convenient for some busy athletes to secure additional protein in the diet, but must not serve as a substitute for natural food.

Nutrients for Metabolic Regulation of Muscle Growth

Levels of serum testosterone, human growth hormone (HGH) and insulin (all anabolic hormones) may influence resistance training and its anabolic effect. Gregory et al (1992) showed that exogenous testosterone administrated had an effect on LBM when normal serum levels are low (delayed puberty). Binners et al (1992) showed that exogenous HGH might increase LBM in male with HGH deficiencies. Deyssig (1993) and Yarasheski et al (1992) however showed no significant anabolic effect when HGH was given to healthy subjects involved in strength training programs. Williams (1993) states that it is likely that nutritional supplements could be effective if they remedied a deficiency and corrected hormonal imbalance, but without effect if the body s hormone receptors are sensitive to naturally occurring testosterone, growth hormone and or insulin. Gelland et al (1987) showed that insulin spare muscle protein from being degraded, but there is no evidence that increase in insulin enhance muscle mass in resistance trained persons.

Amino Acids and Other Nitrogen Containing Substances

Amino acids are used to regulate secretion of HGH, somatomedins and insulin. Grunewald and Bayley (1993) research showed that amino acid mixtures are the largest supplements marketed to bodybuilders. Some studies have showed that high oral doses of ornithine may increase HGH (Bucci et al 1990). Recent research has revealed no significant effect of arginine, lysine, ornithine and tyrosine on HGH or insulin (Fogelholm et al 1993, Lambert et al 1993, Siminski et al 1993, Bucci et al 1992).

Arginine, lysine and ornithine have received most attention in relation of possible effects on strength training. Barron and Vanscoy (1993) cited Elam (1988 and 1989) for scientific support that arginine and ornithine could stimulate HGH and increase LBM. Williams (1992) criticised the studies for questionable statistical analysis. Several other studies have showed no effect on muscle torque or endurance using experienced weight lifters.

Summary - no consistent evidence supporting anabolic or ergogenic effect of amino acid supplementation.

Creatinine

Creatinine is a nitrogen-containing substance found naturally in meat. Combine with phosphate to form creatine phosphate, a high-energy compound stored in the muscle. Recent studies have showed that oral supplements of creatine monohydrate could lead to increased creatine content within the muscle (Harris et al 1992), increased muscle torque with isokinetic exercise (Greeenhaff et al 1993), and improved performance in high intensity cycling exercise (Blasom et al 1993). Blasom et al (1993) also reported an: increase in body mass following supplementation with creatine monohydrate, an increase that could also be due to greater retention of water or synthesis of contractile proteins however additional research is needed for confirmation.

Inosine is a nucleoside and not an amino acid. Advertisements have suggested that it can enhance adenosine triphosphate ATP formation in the muscle and therefor be of value to strength training athletes. However there are no evidence to support these claims.

Choline is an amine found in plant and animal foods. and of importance for development of acetylcholine (neurotransmitter) and in lipid transport. Based on its role supplementation may be hypothesised to increase strength or facilitate loss of body fat. There is no support for this in research (Grunewald and Bailey 1993, Williams 1992).

Vitamins and Minerals

Multivitamin or mineral supplement is one of the most popular products marketed for athletes. Studies report that long term supplementation with multivitamin doesn t enhance sports performance, including strength performance (Singh et al 1992, Telford et al 1992). Even tough several vitamins have been marketed for athletes.

Vitamin B12 is essential for DNA synthesis and thereby hypothesised to stimulate muscle growth. Dibencobal, a coenzyme for B12 is promoted among bodybuilders to increase growth and strength, but no documentation is available for this claim (Williams 1992).

Singh (1992) suggested that antioxidant vitamins C, E and beta-carotene may protect against muscle tissue damage in eccentric strength training program. Early studies produced promising results. Goldfarb summarised the literature in 1993 and noted that athletes may have a greater need for antioxidants, but that more research is needed to decide if they protect against exercise induced muscle damage EIMD.

Carnitine is found naturally in food, particular in meats. It has been suggested that it is ergogenic for aerobic endurance, but well-controlled research suggests otherwise (Decombaz et al 1993). For strength athletes carnitine has been advertised as a mean to facilitate loss of body fat.

Chromium is essential for the glucose-tolerance factor, which potentiates the effect of insulin (Lefavi et al 1992). It has been marketed as an aid for strength athletes. Evans (1989) demonstrated that a daily intake of a chromium picolinate supplement increased LBM and decreased body fat, but this study has been criticised for poor experimental control (Lefavi et al 1992). Recent study with better experimental control revealed no significant effect.

Boron is an essential component of plant foods. Nielsen (1992) noted that boron helped to prevent osteoporosis by increasing postmenopausal women s serum testosterone levels. This led to the belief that it could increase testosterone levels and was written about in muscle magazines. Nielsen later commented that he had misinterpreted his results.

Magnesium is a nutrient with multiple metabolic roles, involvement in protein synthesis and muscle contraction. Some research showed effects on strength (Brilla and Hayley 1992), while other research has not. There is some research on strength and on fatigue.

Lipids

Most lipid derivatives marketed for strength athletes are advertised to provide beneficial effects on metabolic processes. MCT no studies on effect on muscle or weight loss in strength trained athletes. Omega 3 fatty acids found in fish oils may be metabolised in the body to eicosandoids. Bucci (1993) noted that it might stimulate HGH, but again poor study design. Gamma oryzanol is said to increase serum testosterone and HGH, no data support. Smilax is a genus advertised as means to stimulate testosterone production and to increase muscle gains and strength, no scientific support.

See the Summary Table titled "Nutritional Supplements Marketed for Strength-Trained Individuals" (Sports Science Exchange 47 Supplement) from the Gatorade Sports Science Institute.

Exercise Physiology Educational Resources 1998