Nutrition for Muscle Development

Part I

• Efficient/Sufficient diet needed for gains– Aprox. 2300-3500 Cal needed to build 1 lb of

muscle

• Goals for nutrition– Maximize protein synthesis– Minimize protein degredation– Restore muscle fuel stores

• Ensure availability of enzymes and amino acids

• Protein synthesis requires ATP– Replenish energy stores

• Nutrient replacement timing is essential for recovery and gains

Muscle Metabolism

• Building/synthesis = Anabolism

• Breakdown/degradation = Catabolism

• Positive energy = anabolism

• Negative energy = catabolism

• Carbohydrates and fats are primary energy source

• Carbs- stored as glycogen – broken down in muscle/liver to make glucose – metabolized for ATP

• Lipolysis- breakdown of fat for ATP– Long duration, low intensity exercise

• Goal = maintain (+) protein balance

Role of Hormones

• Training effects certain responses

• Roles:– Fuel selection– Nutrient portioning– Gene regulation

• Increased delivery due to blood flow

Insulin

• Stored: pancreas

• Trigger: high levels of blood glucose

• Roles:– Glucose uptake– Glycogen formation– Protein synthesis

Growth Hormone (GH)

• Stored: anterior pituitary gland

• Triggers: exercise, sleep, stress, low plasma glucose

• Roles:– Uptake of amino acids

• Increased amount in anaerobic glycolysis

• Levels vary throughout day

Insulin-like Growth Factor (IGF-I)

• Produced: liver/skeletal muscle

• Trigger: GH presence

• Roles:– Regulates insulin metabolism– Aids growth of tissue– Assists effects of GH

Testosterone

• Produced: male testes and male/female adrenal glands

• Roles:– Anabolic – Androgenic

• Higher levels in males

Estrogen

• Produced: female ovaries, small amounts in male testes

• Roles:– Fat deposition– Female sex characteristics– Unknown exercise benefits

Cortisol

• Produced: adrenal gland• Trigger: exercise, injury, stress• Roles:

– Preserves glucose• Increase fat/protein breakdown

– Use amino acids for energy and repair

– Inhibitory effect on hypertrophy

• Levels fluctuate, increase during training

Male/Female Differences

• Males- better potential for hypertrophy– Increased protein synthesis (testosterone)– Need high net protein balance

• Females- limited in gains for size and strength– Lower testosterone and creatine-kinase

activity