Anderson, Olivia K.; Martinez-Ferran, María; Lorenzo-Calvo, Jorge; Jiménez, Sergio L.; Pareja-Galeano, Helios.

Journal of Strength and Conditioning Research: December 2022 - Volume 36 - Issue 12 - p 3562-3570, doi: 10.1519/JSC.0000000000004101

PURPOSE:

A systematic review that examined the effect of dietary nitrate supplementation (SUP) on muscle strength and hypertrophy when combined with physical exercise.

PROCEDURES:

The databases PubMed, Web of Science, and MEDLINE were searched for full-text articles published between January 2000 and June 2020. For inclusion, studies had to report on the effects of SUP administered as acute or chronic doses together with a standardized exercise protocol on muscle strength and hypertrophy compared with placebo in healthy adults who were sedentary, physically active, or professional athletes. Twelve studies (1,571 subjects) were finally selected.

CONCLUSIONS:

· In five studies, the SUP regime was acute, and in seven, it was chronic.

· SUP was nitrate-rich beetroot juice in nine studies, a potassium nitrate capsule in one, and increased dietary nitrate in 

  two. Ingested nitrate was 64–1,200 mg.

· Of the 12 studies, six observed an ergogenic effect of SUP compared with placebo.

· These findings indicate that muscle strength gains are possible provided the dose, format, frequency, period, and 

  exercise test are appropriate.

· Best results were observed with a minimum acute dose of 400 mg of nitrate provided as beetroot juice/shot taken 2–2.5 

  hours before exercise involving low- and high-intensity muscle contractions. This SUP regime seems to improve muscle 

  efficiency in terms of reduced phosphocreatine and energy costs (P-magnetic resonance spectroscopy) and improved 

  time to exhaustion.

IN PLAIN ENGLISH:

Beet juice/root supplements may have a positive effect on muscle performance.