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Positive Nitrogen Balance

Positive Nitrogen Balance For Muscle Growth

Proteins are nitrogenous (i.e. nitrogen-containing) compounds  made of amino acids which serve as structural building blocks of the human body. Additionally, they are crucial for the synthesis of hormones, enzymes, red blood cells and can also be used secondarily (carbohydrates and fats usually preferred) in energy production. There are three basic states of nitrogen balance. These include:

  • Positive: The optimal state for muscle growth, where the nitrogen intake is greater than nitrogen output. Estentially, this shows that the body has sufficiently recovered from its last workout.
  • Negative: The worst state a bodybuilder can find themselves in, where nitrogen loss is greater than nitrogen intake. Not only is the nitrogen drawn away from  muscle, where it is needed for growth, it is also taken from the vital organs where serious damage can occur. Negative nitrogen balance also destroys muscle and is consequently considered a catabolic state.
  • Equilibrium: The minimum state a bodybuilder should achieve, where nitrogen intake and loss are equal. The trainer in this state is not regressing, nor are they really gaining any appreciable muscle.

Muscle Anabolism vs Catabolism

Generally, a nitrogen balance assessment is used to indicate the level of protein requirement for an individual. A net positive nitrogen balance indicates overall anabolism (protein synthesis is greater than breakdown), where as a net negative nitrogen balance indicates overall catabolism (protein breakdown is greater than synthesis). However, this is only a rough estimate and may be inaccurate as it does not focus solely on exercise. A bout of resistance training induces an anabolic state (heightened protein synthesis), but the body remains in a net negative nitrogen balance without protein supplementation, and may eventually lead to overall catabolism and delayed muscle recovery.

Protein Needed to Build Muscle

Given that dietary protein contributes mainly to anabolic processes of the body; strenuous, high-intensity workouts require more protein to stimulate muscle protein synthesis (MPS) and subsequently aid recovery and adaptation to training. Studies have shown that dietary protein intakes of 1.4-2.4 g/kg daily help sustain a positive nitrogen balance in resistance-trained athletes. The current recommended intake is 2g protein per kg per day for strength training individuals. Additionally, it is important to consider the quality of protein consumed, timing of intake and intensity of training. For example, whey protein isolate (WPI) is a high quality protein as it contains a high-proportion of branched-chain amino acids (BCAAs); crucial for MPS. Studies have shown that a BCAA supplement post-workout can attenuate muscle damage and improve recovery. Consumption of a high-quality protein source with moderate to high carbohydrates is recommended immediately following high-intensity training.

Anabolic Androgenic Steroids (AAS)

The discovery of synthetic testosterone several decades ago has led to increasing use of its derivatives to manufacture anabolic androgenic steroids (AAS). How steroids work:

  • Steroids are used medically to attenuate muscle loss and increase lean mass in patients with chronic illnesses such as AIDS. However, the favourable physiological effects produced by AAS have attracted bodybuilders and athletes leading to sports doping and substance abuse.
  • Generally, AAS modulate the cell’s expression of androgen receptors, subsequently affecting protein synthesis through genetic transcription. A much quicker action is produced by AAS via a non-genomic pathway by transiently increasing calcium levels in the cell which is found to have an important role in growth of skeletal muscle through cell signalling. It is also postulated that AAS has an anti-catabolic effect by inhibiting glucocorticoid (e.g. cortisol) receptor expression in the cell. Though the ability of AAS to induce sufficient muscle growth to enhance performance remains unestablished, it has been recognised that these substances have the ability to attenuate muscle damage.
  • However, most performance-seeking individuals administer AAS doses well above the therapeutic level producing unfavourable side effects. AAS have been found to induce biochemical changes in the central nervous system thereby affecting behaviour often leading to aggression. Furthermore, the cardiovascular effects produced by chronic use of AAS such as hypertension, heart attacks and stroke are well documented. Other long term effects are balding, impotence and masculine characteristics in women.

Make the Right Choices in Bodybuilding

Athletes and bodybuilders have risked the adverse health effects of steroids claiming that they “separate the boys from men.” However, it seems more like a question of personal integrity and mental strength to endure the hardships of training to achieve gold. From an overall perspective, the synergistic approach of nutritional supplements (high quality protein, amino acids, carbohydrates etc.) and a good training regime would be the wiser alternative in improving strength and performance without having to sacrifice health and the quality of life in the long-term.

Bathori, M et al, 'Phytoecdysteroids and Anabolic-Androgenic Steroids-Structure and Effects on Humans' (2008) 15(1) Current medicinal chemistry 75
Campbell, B et al, 'International Society of Sports Nutrition position stand: protein and exercise' (2007) 4 Journal of the International Society of Sports Nutrition 8
Hoffman, JR and MJ Falvo, 'PROTEIN–WHICH IS BEST?' (2004) 3(3) Journal of Sports Science and Medicine 118
Kicman, AT, 'Pharmacology of anabolic steroids' (2008) 154(3) British journal of pharmacology 502
Lambert, CP, LL Frank and WJ Evans, 'Macronutrient considerations for the sport of bodybuilding' (2004) 34(5) Sports Medicine 317
Lynch, GS, JD Schertzer and JG Ryall, 'Anabolic agents for improving muscle regeneration and function after injury' (2008) 35(7) Clinical and Experimental Pharmacology and Physiology 852
Tamaki, T et al, 'Anabolic-androgenic steroid does not enhance compensatory muscle hypertrophy but significantly diminish muscle damages in the rat surgical ablation model' (2009) 132(1) Histochemistry and cell biology 71
van Amsterdam, J, A Opperhuizen and F Hartgens, 'Adverse health effects of anabolic-androgenic steroids' (2010) 57(1) Regulatory Toxicology and Pharmacology 117

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