Branched Chain Amino Acids (BCAAs) Clinical Evidence

Journal of Nutrition;

Shimomura, Y., et. al.  Nutraceutical effects of branched-chain amino acids on skeletal muscle. 2006 Feb;136(2):529S-532S.

Topic:

What are the effects of BCAA supplementation on delayed-onset muscle soreness (DOMS) and muscle fatigue induced by squat exercise in humans?

Background:

A branched chain amino acid complex in skeletal muscle may contribute to muscle protein synthesis and muscle growth. Exercise may increase the BCAA requirement, while BCAA supplementation before exercise reduces the breakdown of muscle proteins during exercise. One of them, leucine, strongly promotes protein synthesis in skeletal muscle in humans and rats, suggesting that a BCAA supplement may attenuate muscle damage induced by exercise and promote recovery from the damage.

Study Type:

Human clinical intervention trial.

Study Design:

Randomized, single blinded, placebo-controlled, crossover

Results:

The results obtained showed that BCAA supplementation prior to squat exercise decreased DOMS and muscle fatigue occurring for a few days after exercise.

Conclusion:

BCAAs may be useful for muscle recovery following exercise.

International Journal of Sports Nutrition Exercise Metabolism 

Shimomura Y, Inaguma A, Watanabe S, Yamamoto Y, Muramatsu Y, Bajotto G, Sato J, Shimomura N, Kobayashi H, Mawatari K. Branched-chain amino acid supplementation before squat exercise and delayed-onset muscle soreness. 2010 Jun;20(3):236-44.

Topic:

What is the effect of branched-chain amino acid (BCAA) supplementation on squat-exercise-induced delayed-onset muscle soreness (DOMS)?

Background:

Elastase is an inflammatory enzyme elevated in  DOMS (delayed-onset muscle soreness) after strenuous exercise. BCAA may have an ameliorating effect on inflammation related to DOMS if taken before exercise. The strenuous type of exercise needed to induce DOMS in this study is the squat exercise, which consisted of 7 sets of 20 squats per set. There were 3-minute intervals between sets. DOMS demonstrated a peak on days 2 and 3. BCAA consisted of the following amino acids in the specific ratio of isoleucine:leucine:valine = 1:2.3:1.2. Leg-muscle force during maximal voluntary isometric contractions was measured 2 days after exercise on day 3. Elastase activity and myoglobin concentration were also measured.

Study Type:

Human clinical intervention trial.

Study Design:

Double-blind, placebo-controlled, randomized crossover

Subjects:

12 young, healthy, untrained female participants

Dosage:

100 mg/kg or an average of 5-6 g for a 5 -60 kg woman

Results:

  • BCAA supplementation suppressed the muscle-force decrease to approximately 80% of the value recorded under the control conditions that were observed in the placebo trial. 
  • BCAA concentrations, which decreased after exercise in the placebo trial, were markedly elevated during the 2-hour postexercise in the BCAA trial.  
  • Serum myoglobin concentration was increased by exercise in the placebo but not in the BCAA trial, demonstrating reduced muscle damage. 

Conclusion:

"The results suggest that muscle damage may be suppressed by BCAA supplementation."

Mechanism of Action

BCAA supplementation before exercise attenuates the breakdown of muscle proteins during exercise in humans, and leucine strongly promotes protein synthesis in skeletal muscle in humans and rats, suggesting that a BCAA supplement may attenuate muscle damage induced by exercise and promote recovery from the damage. BBCA suppresses inflammation through the elastase pathway, reducing muscle damage and helping with repair and recovery.