Amino acid research: Muscle soreness, fat metabolism, and inflammation

L-Carnitine Reduces Muscle Soreness, Shortens Recovery Time

L-carnitine isn’t new by any means, but recent research is further validating its benefits in the context of sports nutrition. Douglas Kalman, PhD, RD, is the vice president of scientific affairs for contract research organization Nutrasource (Guelph, ON, Canada) and co-editor of the Journal of the International Society of Sports Nutrition. Kalman says that a number of amino acids are showing positive effects outside of muscle protein synthesis.

“Amino acids, when combined with electrolyte beverages, outperform typical electrolyte drinks in terms of rehydration and sports performance,” Kalman says. “And when you add in additional dietary sources of amino acids, there’s a reduction in perceived muscle soreness, which some people would argue is a measure of recovery. People don’t limit themselves during exercise when they don’t feel sore-they push harder.”

One study, a 2018 literature review of 32 clinical trials, found that L-carnitine supplementation facilitated exercise recovery, especially in young, healthy subjects. The review, funded by Lonza (Basel, Switzerland), also found that L-carnitine increased muscle mass, improved muscle function, and boosted physical performance in frail and elderly trial subjects.²

Reference
2. Fielding R et al. “L-carnitine supplementation in recovery after exercise.” Nutrients, vol. 10 no. 3 (March 2018): 349-365

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BCAAs and B6 Improve Fat Metabolism

Amino acids aren’t just beneficial for reducing muscle soreness. They can also increase the rate of fat metabolism during exercise when administered in conjunction with vitamin B6.

One randomized, placebo-controlled clinical trial followed 42 overweight and obese women (BMI of 25 to 34.9) over the course of four weeks. All participants in all conditions were assigned a calorie-deficit diet (-500 kcal per day). Participants also received either a daily dose of branched-chain amino acids (6 g) and vitamin B6 (40 mg) (n = 21), or a matching placebo (n = 21). The study authors tracked several measures of body composition, including total cholesterol, LDL/HDL cholesterol, fasting blood sugar, plasma insulin concentrations, bioelectrical impedance analysis scores, and other variables. While this study did not find a statistically significant effect of BCAA plus B6 on weight loss, it did find a statistically significant time-supplementation interaction related to waist-to-hip ratio and lean muscle concentration in the legs.³

Kalman says that amino acids have been shown to promote maintenance of lean muscle mass during exercise: “There’s data to show a retention of fat-free mass during caloric restriction,” Kalman explains. “That’s why amino acids are often used in weight-based sports like wrestling, boxing, and combat MMA.”

Reference
3. Novin Z et al. “The weight loss effects of branched-chain amino acids and vitamin B6: A randomized controlled trial on obese and overweight women.” International Journal for Vitamin and Nutrition Research, vol. 88 no. 1-2 (February 2018): 80-89

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Beta-Alanine Reduces Inflammation during Training

Beta-alanine is not an essential amino acid, but research indicates that it may have beneficial effects during exercise. Its anti-inflammatory properties are particularly noteworthy when considering sports nutrition applications. Clinical trial data provided to Nutritional Outlook by Natural Alternatives International (Carlsbad, CA) indicate that beta-alanine supplementation can help reduce muscle fatigue and inflammation during and after exercise.

One randomized, placebo-controlled clinical trial on 20 military soldiers (average age 20) examined the effects of Natural Alternatives International’s patented beta-alanine ingredient, CarnoSyn, on endurance during a restricted-sleep (five hours of sleep per night) navigational training exercise. Participants were randomly assigned to receive either 12 g per day of CarnoSyn (n=10) or a matching placebo (n=10) for seven days. The soldiers participated in a five-day training mission that required them to travel 28 km per day while carrying 50% of their body mass. At the end of this mission, soldiers returned to base for a seven-day supplementation regimen before participating in a second field mission that required them to travel 10 km per day for five days while carrying a similar load. Participants’ blood concentrations of interleukin-10 were measured after the initial training period and at the end of the study.

This study, funded by Natural Alternatives International, found that CarnoSyn beta-alanine supplementation caused a statistically significant reduction in blood interleukin-10 levels compared to a placebo. The study authors conclude that beta-alanine may enhance the anti-inflammatory response during exercise.⁴

Reference
4. Hoffman JR et al. “Effect of high dose, short-duration β-alanine supplementation on circulating IL-10 concentrations during intense military training.” Journal of Strength & Conditioning Research, vol. 32, no. 10 (October 2018): 2978-2981

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Amino Acid Market Set to Grow

Amino acids are demonstrating efficacy as workout supplements, with studies confirming their ability to increase muscle mass, boost fat metabolism, and reduce inflammation when paired with exercise. As consumers look for more natural workout supplements with strong clinical research behind them, expect demand for amino acid supplements to increase, both in the strength training market and in the healthy lifestyle market.

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