As a fundamental building block of human nutrition, there is no doubt that amino acids have a wide range of effects on the body, especially when they are lacking. Here is a short bibliography of the ergogenic effects observed in research over the past few decades.

* = study is referenced more than once

Amino Acids and Protein Synthesis:

Essential amino acids increase protein synthesis by transitioning it to positive synthesis.

An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein. (Biolo et al 1997)

Postexercise net protein synthesis in human muscle from orally administered amino acids. (Tipton et al 1999)

An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. (Rasmussen et al 2000)*

Effects of amino acid intake on anabolic processes. (Wolfe 2001)

Hyperaminoacidemia during rest increases protein synthesis:

Increased rates of muscle protein turnover and amino acid transport after resistance exercise in humans. (Biolo et al 1995)

Effects of flooding amino acids on incorporation of labeled amino acids into human muscle protein. (Smith et al 1998)

Human muscle protein synthesis is modulated by extracellular, not intramuscular amino acid availability: a dose-response study. (Bohe et al 2003)

Regulation of muscle protein by amino acids. (Wolfe 2002)

Amino acid availability may be more limiting than energy availability for postworkout protein synthesis:

Postexercise protein intake enhances whole-body and leg protein accretion in humans. (Levenhagen et al 2002)*

The interaction of postexercise metabolic processes and increased amino acid availability maximize the stimulation of muscle protein synthesis and results in even greater muscle anabolism than when dietary amino acids are not present.

An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. (Rasmussen et al 2000)*

Exercise, protein metabolism, and muscle growth. (Tipton, Wolfe 2001)*

Synergy between carbohydrates and amino acids

Independent and combined effects of amino acids and glucose after resistance exercise.(Miller et al 2003)

Postexercise protein intake enhances whole-body and leg protein accretion in humans. (Levenhagen et al 2002)*

The influence of post-exercise macronutrient intake on energy balance and protein metabolism in active females participating in endurance training. (Roy et al. 2002)

Effect of an amino acid, protein, and carbohydrate mixture on net muscle protein balance after resistance exercise. (Borsheim et al 2004)

Influence of exercise mode and carbohydrate on the immune response to prolonged exercise. (Henson et al 1999)

Effect of carbohydrate intake on net muscle protein synthesis during recovery from resistance exercise. (Borsheim et al 2004)

Amino acids and glycogen synthesis

Reversal of fatigue during prolonged exercise by carbohydrate ingestion late in exercise (Coggan and Coyle 1987)

Muscle glycogen during prolonged severe exercise. (Hermansen 1967)

Effect of carbohydrate ingestion on glycogen resynthesis in human liver and skeletal muscle, measured by (13)C MRS. (Casey et al 2000)

Only Essential Amino Acids are required for Protein Synthesis

Exercise, protein metabolism, and muscle growth. (Tipton, Wolfe 2001)*

Leucine modulates protein synthesis, proliferation and insulin release

Metabolic regulation by leucine of translation initiation through the mTOR-signaling pathway by pancreatic beta-cells. (Xu et al 2001)

Gender differences in leucine kinetics and nitrogen balance in endurance athletes. (Phillips et al 1985)

Timing is critical with Amino Acid delivery:

Research has shown that timing can make a huge difference in recovery and performance. Free form amino acids such as Myothon™ are absorbed in the body in under half an hour, providing superior results than even the fastest whole proteins.

Training in combination with immediate amino acid administration has been shown to augment protein synthesis acutely

An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein. (Biolo et al 1997)

An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. (Rasmussen et al 2000)*

Loss of benefits from amino acid supplementation, even after short delays

Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis. (Levenhagen et al 2001)

Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. (Tipton et al 2001)*

The effect of resistance training combined with timed ingestion of protein on muscle fiber size and muscle strength.(Andersen et al 2005)

Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. (Esmarck et al 2001)

Slow and fast dietary proteins differently modulate postprandial protein accretion. (Boirie et al 1997)

Benefits seen from amino acid supplementation preworkout and intraworkout

Effect of a 4:1 ratio carbohydrate/protein beverage on endurance performance, muscle damage, and recovery. (Romano et al 2004)

Effect of a carbohydrate-protein supplement on endurance performance during exercise of varying intensity. (Ivy et al 2003)

Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. (Tipton et al 2001)*

Amino Acids in Sports:

Greater adaptations to excess amino acids in trained athletes:

Evaluation of protein requirements for trained strength athletes. (Tamopolsky et al 1992)

Amino acid quality is important for athletes:

Amino acid supplementation and exercise performance. Analysis of the proposed ergogenic value. (Kreider et al 1993)

International Society of Sports Nutrition position stand: protein and exercise. (Campbell et al 2007)

Amino acids attenuate the effects of overtraining:

The overtrained state has been found in up to 30% of team and 48% individual athletes. (Kentta et al 2001)

training overreaching. (Kraemer et al 2006)

Administration of branched-chain amino acids during sustained exercise–effects on performance and on plasma concentration of some amino acids. (Blomstrand et al 1991)*

Effect of branched-chain amino acid supplementation on mental performance. (Blomstrand et al 1991)

Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. (Lemon et al 1985)

Influence of paroxetine, branched-chain amino acids and tyrosine on neuroendocrine system responses and fatigue in humans. (Struder et al 1998)

Effects of branched-chain amino acids and carbohydrate on fatigue during intermittent, high-intensity running. (Davis et al 1999)

Overtraining and glycogen depletion hypothesis. (Snyder 1998)

Changes in plasma concentrations of aromatic and branched-chain amino acids during sustained exercise in man and their possible role in fatigue. (Blomstrand et al 1988)

Effects of amino acids on exercise capacity:

Effects of a carbohydrate-protein beverage on cycling endurance and muscle damage. (Saunders et al 2004)

Branched-chain amino acids prolong exercise during heat stress in men and women (Mittleman et al 1998)

Administration of branched-chain amino acids during sustained exercise–effects on performance and on plasma concentration of some amino acids. (Blomstrand et al 1991)*

Effects of branched-chain amino acids and carbohydrate on fatigue during intermittent, high-intensity running. (Davis et al 1999)

Increased demand for amino acids in athletes:

Dietary protein requirements in athletes. (Lemon 1997)

Beyond the zone: protein needs of active individuals. (Lemon 2000)

Protein and amino acids for athletes. (Tipton and Wolfe 2004)

Protein and amino acid metabolism during and after exercise and the effects of nutrition. (Rennie and Tipton 2000)

Effects of exercise on dietary protein requirements.(Lemon 1991)

Protein intake and athletic performance. (Lemon and Proctor 1991)

Role of protein in exercise. (Rankin 1999)

Protein requirements for endurance athletes. (Tarnopolsky 2004)

Macronutrient considerations for the sport of bodybuilding. (Lambert et al 2004)

Evaluation of protein requirements for trained strength athletes (Tarnopolsky et al 1986)

Amino Acids and Weight Loss:

Dietary protein impact on glycemic control during weight loss. (Layman and Baum 2004)

Amino Acid-Carbohydrate Intake Combined with Multiple Bouts of Resistance Exercise Increases Resting Energy Expenditure. (Hackney et al 2013)

Independent and combined effects of liquid carbohydrate/essential amino acid ingestion on hormonal and muscular adaptations following resistance training in untrained men. (Bird et al 2006)

Protein and Amino Acid Quality

Human amino acid requirements: can the controversy be resolved? (Fuller and Garlick 1994)

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