Influence of Equimolar Doses of Beetroot Juice and Sodium Nitrate on Time Trial Performance in Handcycling

Abstract

This study aimed to investigate the influence of a single dose of either beetroot juice (BR) or sodium nitrate (NIT) on performance in a 10 km handcycling time trial (TT) in able-bodied individuals and paracyclists. In total, 14 able-bodied individuals [mean ± SD; age: 28 ± 7 years, height: 183 ± 5 cm, body mass (BM): 82 ± 9 kg, peak oxygen consumption (VO2peak): 33.9 ± 4.2 mL/min/kg] and eight paracyclists (age: 40 ± 11 years, height: 176 ± 9cm, BM: 65 ± 9 kg, VO2peak: 38.6 ± 10.5 mL/min/kg) participated in the study. All participants had to perform three TT on different days, receiving either 6 mmol nitrate as BR or NIT or water as a placebo. Time-to-complete the TT, power output (PO), as well as oxygen uptake (VO2) were measured. No significant differences in time-to-complete the TT were found between the three interventions in able-bodied individuals (p = 0.80) or in paracyclists (p = 0.61). Furthermore, VO2 was not significantly changed after the ingestion of BR or NIT in either group (p < 0.05). The PO to VO2 ratio was significantly higher in some kilometers of the TT in able-bodied individuals (p < 0.05). The ingestion of BR or NIT did not increase handcycling performance in able-bodied individuals or in paracyclists.

Physiology of handcycling: A current sports perspective

“…Further, while factors such as abdominal strapping are perceived by athletes to provide stability and more efficient power transfer, 12,24 their use is rarely reported in studies with only Meyer et al making note of this in their methods. 33 Among trained handcyclists, VO 2peak values greater than 3.0 L min −1 , or >40.0 ml kg −1 min −1 , have recently been reported by several researchers during ACE, 28 and recumbent [34][35][36] or kneeling 37 handcycling; this has been achieved by participants in the H3/H4 and H5 categories, respectively. These values of aerobic capacity are accompanied by 5-6 years of handcycling experience 28,36 and 6 ± 2 training sessions per week comprising of 223 ± 57 km wk −1 .…”

“…While there is less information available for athletes in the more impaired H1 and H2 classes, data from these athletes indicate VO 2peak values of 1.1 ± 0.4 to 2.0 ± 0.4 L min −1 may be achieved with higher values reflected by a longer involvement in the sport. 16,29,33,37 Recent work by Flueck et al displayed a clear relationship of aerobic capacity and classification by showing that the H1 class athlete had a much lower VO 2peak than the H5 class athlete (1.3 vs. 3.7 L min −1 or 17.3 vs. 49.7 ml kg −1 min −1 ), 37 with this likely explained by the significantly greater active musculature due to athletes' impairment. Furthermore, the utilization of trunk muscles for propulsion creates added oxygen demand during kneeling versus recumbent handcycling, 14,26,39 again explaining the direct relationship between athletes' classification and aerobic capacity shown previously.…”

“…16 Authors have reported PO peak values of 98-150 W, 240-250 W, or 220 W in trained H1/H2, H3/H4, and H5 handcyclists, respectively. 6,24,[35][36][37] However, it must be acknowledged that large variability exists in the protocols employed when determining PO peak from maximal incremental tests to exhaustion, especially regarding stage durations and workload increments during incremental tests ( Table 2) and definition of PO peak ; thus, comparisons between studies are limited.…”

“…5,31 During simulated 10 and 16 km TT performance on a Cyclus 2 ergometer (RBM electronic automation GmbH), average velocities of ~ 33 km h −1 , equating to 142 ± 49 to 174 ± 15 W, ~170 b min −1 , and ~ 10.0 mmol L −1 [BLa -] have recently been documented in trained handcyclists. 36,37 The average velocities reported for the TT distances of 10-22 km, ranged from 4.9 km h −1 in a 20.2 km mountain climb TT with 863 m elevation gain to 34.5 km h −1 over self-reported best 20 km time. 28,29 However, it is noted that these velocities are considerably lower than the 43.4 km h −1 achieved by a male H4 handcyclist in the 20 km 2016 Paralympic TT, 4 which suggests that more research is warranted in this area for sports scientists and coaches to fully appreciate the performance diagnostics of truly elite athletes competing currently.…”

Diet in neurogenic bowel management: A viewpoint on spinal cord injury

“…However, the positive effects of beetroot juice seen in young individuals were not observed in older adults [145] . In a recent randomized (placebocontrolled) cross-over study in upper body trained able-bodied individuals and Paracyclists with SCI (lesion level between C4 and L4), Para-cyclists showed higher nitrate concentrations after beetroot juice, whereas no differences were found in performance in either group [146] . Although a meta-analysis reported nitrate-independent blood pressure lowering effects of beetroot juice [147] and we found only a case report of interaction with methotrexate [148] , supplementation in patients with in CKD requires further studies [149] .…”