Nitrate Supplementation on Motor Unit Activity

Northumbria University14 enrolled

Overview

This study aimed to assess if nitrate supplementation influence motor unit (MU) activity following a sustained ischemic contraction and whether this is affected by blood flow restriction (BFR) during the recovery period. Fourteen male participants (mean ± SD, 25 ± 6 years) completed two experimental trials following 5-days of supplementation with either nitrate-rich (NIT) or nitrate-depleted (PLA) beetroot juice in a randomized, double-blinded, cross-over design. Intramuscular electromyography was used to assess MU potential (MUP) size and firing rates (MUFR) during a submaximal (25% MVC) sustained isometric contraction with BFR. These variables were also assessed during a 90 s recovery period with the first half completed with, and the second half completed without, BFR. Nitrate supplementation can expedite the recovery of MUP duration following a sustained ischemic contraction in healthy adults. These novel observations improve understanding of the effects of nitrate on the recovery of neuromuscular function post-exercise and might have implications for recovery of muscle contractile function.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

OTHER

Masking

DOUBLE

Enrollment

Conditions

Dietary Supplements Healthy

Nitrate supplementationDIETARY_SUPPLEMENT

Participants ingested 2 × 70 mL/day shots of concentrate nitrate-rich (\~12.8 mmol/day nitrate) or nitrate-depleted (\~0.08 mmol/day nitrite) beetroot juice (Beet It, James White Drinks Ltd., Ipswich, UK). Two shots were supplemented for 5 days; one each morning (\~9 am) and one each evening (\~9 pm) except for the day of the experimental trial when both shots were taken together 2.5 h before the experimental trial.

Placebo supplementtaionDIETARY_SUPPLEMENT

2 × 70 mL/day shots of concentrate nitrate-depleted (\~0.08 mmol/day NO3-) beetroot juice. Two shots were supplemented for 5 days; one each morning (\~9 am) and one each evening (\~9 pm) except for the day of the experimental trial when both shots were taken together 2.5 h before the experimental trial.

Eligibility

Sex: MALEMin age: 18 YearsMax age: 30 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Male between 18 - 30 years * free from known respiratory insufficiency, cardiovascular disease and neuro-musculo-skeletal problems at present or in the preceding 6 months. * having at least 5 years competitively (team) sport experience. Exclusion Criteria: * having cardiovascular disease, neuromuscular disease and any lower limb injury and treatment for chronic respiratory complaints.

Outcomes

Primary Outcomes

Plasma Nitrite Level

concentration \[nmol\]

Time frame: Pre-exercise

Motor Unit Activity

Duration (ms), area (uV.ms), firing rate (Hz)

Time frame: Pre-exercise, post-exercise, recovery (45 s)