Beetroot-Based Gel Improves Forearm Reoxygenation and Strength after Exercise in Elderly with Cardiovascular Risk Factors.

Abstract

Muscle oxidative capacity and recovery time of muscle oxygenation following maximal exercise decline with the aging. Although dietary nitrate supplementation has been shown to improve muscle oxygenation in health subjects, these effects in elderly has not been addressed. PURPOSE: To evaluate the effect of a beetroot-based nutritional gel (BG) on forearm muscle oxygenation, blood volume and handgrip strength in elderly with cardiovascular risk factors. METHODS: 12 elderly participated in a randomized, double-blind and crossover study. Maximal voluntary contraction (MVC) was collected for baseline, immediately and 20 min after exercise in both BG (100 g of beetroot-based gel containing approx. 12 mmol nitrate) or PLA (100 g of nitrate-depleted gel nitrate-depleted) were provided. After 150 min of ingestion of each intervention, elderly performed a rhythmic handgrip exercise which consisted of one 1-min sets at 30 % of the MVC of each subject following 1 min of quiet recovery after exercise. Muscle deoxygenation (SmO2min), muscle reoxygenation (SmO2max), muscle deoxygenation time (SmO2½DT), muscle reoxygenation time (SmO2½RT) and bood volume (tHb) were continuously monitored using an NIRS device. RESULTS: significant reduction in SmO2min and SmO2½DT was observed during exercise and SmO2½RT during recovery, as it was in the ΔMVC (BG: -18.56±13.8 vs. PLA: -26.18±14.6 N; P<0.05) only 20 min after handgrip exercise. Significant increase in tHb during and after exercise was observed in BG. There was no significant difference in SmO2max between interventions. CONCLUSION: Single dose of BG improve microvascular hemodynamic which may accelerate the muscle recovery after short exercise in elderly with cardiovascular risk factors. Supported by FAPERJ (E-26/010.002692/2014) and CNPq (442977/2014-0) Grant.Table 1: Values of near-infrared spectroscopy (NIRS) during exercise and recovery period of exercise.