Acute beetroot juice administration improves peak isometric force production in adolescent males

• Published in: Applied physiology, nutrition, and metabolism nutrition, and metabolism, 2018-08, Vol.43 (8), p.816-821
• Main Authors: Bender, David, Townsend, Jeremy R, Vantrease, William C, Marshall, Autumn C, Henry, Ruth N, Heffington, Stephen H, Johnson, Kent D
• Format: Article
• Language: English
• Subjects: Adolescent; Age Factors; anaerobic exercise; Athletic ability; Beets; Beta vulgaris; Cross-Over Studies; dietary nitrates; Double-Blind Method; entraînement par intervalle d’intensité élevée; exercice anaérobie; Exercise; Exercise Test; Fruit and Vegetable Juices; Health aspects; high-intensity interval training; Humans; Isometric Contraction - drug effects; jeunesse; Male; Males; Muscle Fatigue - drug effects; Muscle Strength - drug effects; Muscle, Skeletal - drug effects; Muscle, Skeletal - physiology; nitrate alimentaire; Nitrates; Nitrates - administration & dosage; Nitrates - adverse effects; nitric oxide; oxyde nitrique; Physiological research; Plant products; Plant Roots; Running; Sex Factors; Teenagers; Tennessee; Time Factors; Treatment Outcome; youth
• ISSN: 1715-5312; 1715-5320
• DOI: 10.1139/apnm-2018-0050

The purpose of this study was to examine the effects of acute beetroot juice (BR) administration on repeated sprint performance and isometric force production in adolescent males. Twelve male adolescents (age, 16.8 ± 1.0 years; height, 178.8 ± 9.2 cm; mass, 74.8 ± 12.5 kg; peak height velocity, 2.53 ± 1.2 years) participated in this double-blind, placebo-controlled, crossover designed study. Participants consumed 2 × 70 mL of BR (∼12.9 mmol NO 3 − ; Beet It Sport) or a nitrate-depleted placebo (PL) at 2.5 h prior to performing isometric mid-thigh pulls (IMTP) and 4 repeated 20-s Wingate sprints interspersed with 4 min of rest. Sprint data were analyzed by a 2 × 4 (group × time) repeated-measures ANOVA while a dependent t test was used to compare conditions for IMTP peak force. A significant main effect for time (p < 0.05) was observed for peak power (PP), average power (P avg ), and fatigue index (FI) across sprints. Compared with sprint 1, sprint 4 resulted in significant decreases in PP (p < 0.000; −16.6%) and P avg (p = 0.000; −21.8%) and FI was significantly elevated (p < 0.000; 15.2%). No significant group × time interactions were observed between conditions for PP (p = 0.402), P avg (p = 0.479), or FI (p = 0.37). IMTP peak force was significantly higher (p = 0.004; 13.9%) following BR consumption compared with PL. The repeated sprint protocol resulted in significant fatigue while BR did not influence sprint performance. However, it appears BR administration may improve peak force production in adolescent males.