de Oliveira Gustavo Vieira, Morgado Marina, Conte-Junior Carlos Adam, Alvares Thiago Silveira
Nutrition and Exercise Metabolism Research Group, Nutrition Institute, Universidade Federal do Rio de Janeiro, Macaé, Rio de Janeiro, Brazil.
Department of Food Technology, Universidade Federal Fluminense, Macaé, Brazil.
PLoS One. 2017 Nov 30;12(11):e0188893. doi: 10.1371/journal.pone.0188893. eCollection 2017.
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.
运动后肌肉氧合的恢复时间和肌肉力量都会随着年龄的增长而下降。虽然食用甜菜根已被证明可以改善成年人的肌肉氧合和运动表现，但这些影响在老年人中尚未得到研究。本研究的目的是评估基于甜菜根的凝胶（BG）对老年人肌肉氧饱和度、血容量（总血红蛋白，tHb）和握力的影响，这些影响是针对握力运动而言的。在随机交叉双盲设计中，12名老年受试者食用BG（100克含约12毫摩尔硝酸盐的基于甜菜根的凝胶）或PLA（100克硝酸盐耗尽的凝胶）。受试者进行有节奏的握力运动，包括以每个受试者最大自主收缩（MVC）的30%进行1分钟的一组运动，随后休息1分钟。使用近红外光谱法连续监测肌肉氧合参数和tHb。在基线、运动后立即和运动后30分钟评估MVC。与PLA组相比，BG组运动恢复期间的肌肉氧再饱和率更高（1.43±0.77对1.02±0.48%·s-1；P<0.05）。运动恢复期间观察到tHb显著增加（10.25±5.47对6.72±4.55μM；P<0.05），并且在BG组中运动后30分钟观察到握力下降显著减少（-0.24±0.18对-0.39±0.20 N；P<0.05）。总之，单剂量的基于甜菜根的凝胶可加快老年人握力运动后肌肉氧的再饱和，增加血容量并改善握力恢复。
