Differential Effect of Metabolic Alkalosis and Hypoxia on High-Intensity Cycling Performance

Abstract

Flinn, S, Herbert, K, Graham, K, and Siegler, JC. Differential effect of metabolic alkalosis and hypoxia on high-intensity cycling performance. J Strength Cond Res 28(10): 2852-2858, 2014-The purpose of this study was to investigate the effects of sodium bicarbonate (NaHCO 3 ) ingestion and acute hypoxic exposure on repeated bouts of high-intensity cycling to task failure. Twelve subjects completed 4 separate intermittent cycling bouts cycling bouts to task failure (120% peak power output for 30-second interspersed with 30-second active recovery) under the following conditions: normoxia (F I O 2 % at 20.93%) alkalosis (NA), normoxia placebo (NP), hypoxia (F I O 2 % at 14.7%) alkalosis (HA), and hypoxia placebo (HP). For the NA and HA trials, the buffer solution (0.3 g$kg 21 of NaHCO 3 ) was dispensed into gelatin capsules and consumed over 90 minutes with 1 L of water. Whole-blood acidbase findings demonstrated metabolic alkalosis in both NA and HA before exercise (HCO 3 2 : 32.8 6 1.8 mmol$L 21 ). Time to task failure was significantly impaired in the hypoxic conditions (NA: 199.1 6 62.3 seconds, NP: 183.8 6 45.0 seconds, HA: 127.8 6 27.9 seconds, HP: 133.3 6 28.7 seconds; p , 0.001; h 2 = 0.7). There was no difference between the HA and HP conditions (p = 0.41); however the 2 normoxic conditions approached significance with the NA condition on average resulting in approximately 15-second improvement in time to task failure (p = 0.09). These findings suggest that an acute decline in F I O 2 % consistent with hypoxic exposure is more inhibiting than metabolic acidosis during intermittent highintensity cycling to task failure. In application, the use of hypoxia and NaHCO 3 concurrently to improve performance under these conditions does not seem warranted. Figure 2. Time to task failure (s) for the 4 trial conditions (NA, NP, HA, and HP). Data are presented as mean 6 SD. *Significantly different from hypoxic conditions (p , 0.001). NA = normoxia alkalosis; NP = normoxia placebo; HA = hypoxia alkalosis; HP = hypoxia placebo.Figure 3. Individual performance data represented as responders, nonresponders, and negative responders. Journal of Strength and Conditioning Research the TM | www.nsca.com

The effects of sodium bicarbonate ingestion on cycling performance and acid base balance recovery in acute normobaric hypoxia

“…The current study findings contrast with previous investigations reporting no effect of NaHCO3 ingestion on performance in moderate normobaric hypoxic conditions equivalent to m (Saunders et al, 2014, Flinn et al, 2014. The current study findings instead support recent investigations by Deb et al (2017) who reported 0.3 g .…”

Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis

“…The current investigation is the first to demonstrate a significant and meaningful improvement in performance from NaHCO 3 under acute hypoxic conditions, in contrast with as previous investigations reporting no effect (Saunders et al 2014b; Flinn et al 2014). The conflicting results to previous investigations may be attributed to the intensity and type of exercise, which were supra-maximal and intermittent in both previous studies, or the training status of participants, who were recreationally trained.…”

“…Nevertheless, blood gas parameters (e.g. pH and HCO 3 − ) are suggested to unaltered between arterialised and non-arterialised blood samples (Stannard et al 2016) and therefore, the results remain valid; while also remaining consentient with previous scientific literature (Flinn et al 2014; Saunders et al 2014a, b; Froio de Araujo Dias et al 2015; Miller et al 2016) Furthermore, it is suggested future investigations should consider obtaining muscle biopsy and arteriovenous balance analysis to understand the metabolic response to NaHCO 3 ingestion on W’.…”

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

“…Few studies have examined the effect of NaHCO 3 ingestion on anaerobic exercise performance at altitude, and the results of recent studies have been inconsistent. Flinn et al [20] and Saunders et al [21] found no effect of NaHCO 3 supplementation on the power output of intermittent high-intensity exercise at simulated altitudes of 3000 m and 2500 m, respectively, while several studies have supported the assumption of a beneficial effect of NaHCO 3 ingestion on anaerobic performance at altitude. Feriche Fernandez-Castanys et al [22], Hauswirth et al [23], and McLellan et al [24] all described increased or constant exercise performance under acute altitude conditions in hypoxic chambers compared with sea-level performance in subjects receiving alkalizing agent supplements prior to exercise.…”