Acute effect of dietary nitrate on forearm muscle oxygenation, blood volume and strength in older adults: A randomized clinical trial

Abstract

Both recovery time of post-exercise muscle oxygenation and muscle strength decline with aging. Although beetroot consumption has been shown to improve muscle oxygenation and exercise performance in adults, these effects in the elderly has not been addressed. The aim of the present study was to evaluate the effect of a beetroot-based gel (BG) on muscle O2 saturation, blood volume (tHb) and handgrip strength in the elderly in response to handgrip exercise. In a randomized crossover double-blind design, twelve older subjects consumed BG (100 g of beetroot-based gel containing ~ 12 mmol nitrate) or PLA (100 g of nitrate-depleted gel nitrate-depleted). The subjects performed a rhythmic handgrip exercise which consisted of a one 1-min set at 30% of the maximal voluntary contraction (MVC) of each subject, followed by a 1 min recovery. The muscle oxygenation parameters and tHb were continuously monitored by using near-infrared spectroscopy. MVC was evaluated at baseline, immediately after exercise, and 30 min afterwards. The muscle O2 resaturation rate during exercise recovery was greater in the BG when compared to PLA condition (1.43 ± 0.77 vs 1.02 ± 0.48%.s-1; P < 0.05). Significant increase was observed in tHb during exercise recovery (10.25 ± 5.47 vs 6.72 ± 4.55 μM; P < 0.05) and significant reduction of handgrip strength decline was observed 30 min after exercise in BG (- 0.24 ± 0.18 vs—0.39 ± 0.20 N; P < 0.05). In summary, a single dose of a beetroot-based gel speeds up muscle O2 resaturation, increases blood volume and improves recovery of handgrip strength after handgrip exercise in older adults.

Dietary nitrate improves skeletal muscle microvascular oxygenation in HIV-infected patients receiving highly active antiretroviral therapy: a randomised, double-blind, cross-over, placebo-controlled study

“…An a priori power analysis was conducted (G*Power, version 3.0.1) for a paired t test. On the basis of statistical power (1 -β) of 0•80, an effect size of 0•7 (based on our findings from Oliveira et al (7) study) and an overall level of significance of 0•05, at least fifteen participants were needed to detect a statistical difference in NIRS parameters (main outcome). To identify differences in SmO 2 and tHb parameters, salivary nitrate and nitrite, ETF and MVC between the NR-BJ and ND-BJ interventions, a paired t test was used.…”

“…The rhythmic handgrip exercise consisted of one bout of rhythmic handgrip exercise at 30 % of MVC until exhaustion, followed by 2 min of recovery. The rhythmic handgrip exercise consisted of isotonic contractions of forearm muscles at a controlled rate (sixty contractions per min, 0•5 s contraction/0•5 s relaxation, determined using a metronome) and range of motions (10-cm excursion of the pulley wire with each contraction), as previously described (7,10) . A high contraction frequency cadence of exercise was chosen, since previous studies have suggested that the reduction of nitrite to NO is favoured as a high contraction frequency is performed (11,12) .…”

“…Muscle oxygen saturation may be measured non-invasively by near-IR spectroscopy (NIRS), which provides information into the ability of muscles to extract oxygen from the capillaries and the ability of microvasculature to respond to a stimulus (6) . Recently we demonstrated that a single dose of a beetroot-based gel (rich in dietary nitrate) improved muscle oxygen resaturation rate in older people (7) and physically active individuals (8) in response to a handgrip exercise protocol, and these improvements were accompanied by increases in urinary nitrate and nitrite (7) . However, to our knowledge, in vivo skeletal muscle oxygen saturation in HIV-infected patients after beetroot juice intake has not yet been examined.…”

A Narrative Review on the Potential of Red Beetroot as an Adjuvant Strategy to Counter Fatigue in Children with Cancer

“…The favorable effects of beetroot juice do not appear to be limited to aerobic exercise; benefits for muscle strength have also been reported. In one such study, in an elderly population, de Oliviera et al found that acute intake of a beetroot-based gel attenuated the decline in handgrip strength following fatiguing handgrip exercise, indicating that beetroot juice might also be useful for counteracting the decline in muscle strength and power associated with age [69,70].…”

Beetroot-based gel supplementation improves handgrip strength and forearm muscle O2 saturation but not exercise tolerance and blood volume in jiu-jitsu athletes

“…The rhythmic handgrip exercise began approximately 120 min after the nutritional supplementation (T120) and lasted for approximately 10 min. Exercising minutes after beetroot gel consumption was chosen based on previous studies demonstrating bioconversion of the dietary nitrate into nitrite at 120-150 min after beetroot ingestion (Fulford et al, 2013;Wylie et al, 2013;Coggan et al, 2015;Oliveira et al, 2017).…”