The ingestion of sodium bicarbonate (NaHCO 3 ) is well accepted as an efficacious ergogenic aid to improve short-duration, high-intensity exercise performance. 1 The exogenous intake of NaHCO 3 acts as an extracellular buffer, raising blood pH and bicarbonate (HCO 3 − ) concentrations and
Alannah K.A. McKay, Peter Peeling, Martyn J. Binnie, Paul S.R. Goods, Marc Sim, Rebecca Cross, and Jason Siegler
Keita Kinoshita, Eric MacIntosh, and Shintaro Sato
to Gucciardi et al. ( 2017 ), MT has the potential to be a personal resource that would buffer the maladaptive effect of uncontrollable factors (e.g., coaching behaviors) on thriving. The results suggest that MT might be a personally controllable factor to protect youths from the negative effect of
Michael D. Nelson, Lynneth A. Stuart-Hill, and Gordon G. Sleivert
To evaluate the influence of acute hypervolemia, achieved through the ingestion of a sodium citrate-rich beverage, on cardiovascular strain and thermoregulatory function, during moderate-intensity aerobic exercise in a warm environment. Sodium citrate’s ability to increase buffering capacity was also assessed.
Twelve endurance-trained athletes completed two blind randomized treatment trials, separated by a minimum of seven days, on a cycle ergometer under heat stress (30.9°C, 64% RH). The subjects ingested 12 mL·kg−1of (1) Gatorade, the control (CNT), or (2) sodium-citrate plus Gatorade (NaCIT: 170 mmol Na+L−1) before cycling at 15% below ventilatory threshold (VT) for 62 minutes. Core and skin temperature, expired gas samples, heart rate, and perceived exertion were measured throughout exercise. Blood samples were taken before drinking each beverage, before commencing exercise, and throughout the exercise bout.
Plasma volume (PV) was significantly expanded in the NaCIT trial (3.6 ± 5.5%) and remained significantly higher throughout exercise in the NaCIT trial compared with the CNT trial (P ≤ .05). No significant differences were found in heart rate, in core and skin temperature, or in the metabolic data between the treatment groups. NaCIT significantly increased [HCO3 −], base excess, and pH throughout the trial.
Acute oral ingestion of high-sodium citrate beverages before moderate exercise induces mild levels of hypervolemia and improves blood-buffering capacity in humans; however, mild hypervolemia during 62 minutes of moderate exercise does not reduce physiological strain or improve thermoregulation.
Rebecca L. Jones, Trent Stellingwerff, Paul Swinton, Guilherme Giannini Artioli, Bryan Saunders, and Craig Sale
“check-in” time) to finish warm-ups 20–40 min prior to competition, allowing for greater recovery ( Ingham et al., 2013 ). It is unknown if SB supplementation prior to a HI or LI warm-up would be similarly effective due to buffering requirements during the warm-up itself. Although HI athletes will
Melinda Jane Craike, Denis Coleman, and Clare MacMahon
This study examined the role of leisure-time physical activity in reducing the impact of high life stress and time pressure on depression, a buffer effect, for mothers of infants. A direct association between leisure-time physical activity and depression, regardless of both sources of stress, was also tested. A sample of approximately 5,000 mothers of infant children completed questionnaires that measured demographic characteristics, frequency of participation in leisure-time physical activity, life stress, time pressure, and depression (depressive symptoms). Hierarchical multiple regression incorporating an interaction component to represent the buffering effect was used to analyze the data. Frequency of leisure-time physical activity was significantly associated with lower levels of depressive symptoms for both types of stress and acted as a buffer of the association between life stress and depressive symptoms, but did not buffer the influence of time pressure on depressive symptoms. These findings indicated that leisure-time physical activity assists in maintaining the mental health of mothers of infants; however, caution is needed when promoting physical activity for mothers who feel under time pressure.
Bryan Saunders, Craig Sale, Roger C. Harris, and Caroline Sunderland
To investigate the separate and combined effects of sodium bicarbonate and beta-alanine supplementation on repeated sprints during simulated match play performed in hypoxia.
Study A: 20 recreationally active participants performed two trials following acute supplementation with either sodium bicarbonate (0.3 g·kg−1BM) or placebo (maltodextrin). Study B: 16 recreationally active participants were supplemented with either a placebo or beta-alanine for 5 weeks (6.4 g·day−1 for 4 weeks, 3.2 g·day−1 for 1 week), and performed one trial before supplementation (with maltodextrin) and two following supplementation (with sodium bicarbonate and maltodextrin). Trials consisted of 3 sets of 5 × 6 s repeated sprints performed during a football specific intermittent treadmill protocol performed in hypoxia (15.5% O2). Mean (MPO) and peak (PPO) power output were recorded as the performance measures.
Study A: Overall MPO was lower with sodium bicarbonate than placebo (p = .02, 539.4 ± 84.5 vs. 554.0 ± 84.6 W), although there was no effect across sets (all p > .05). Study B: There was no effect of beta-alanine, or cosupplementation with sodium bicarbonate, on either parameter, although there was a trend toward higher MPO with sodium bicarbonate (p = .07).
The effect of sodium bicarbonate on repeated sprints was equivocal, although there was no effect of beta-alanine or cosupplementation with sodium bicarbonate. Individual variation may have contributed to differences in results with sodium bicarbonate, although the lack of an effect with beta-alanine suggests this type of exercise may not be influenced by increased buffering capacity.
William H. Gurton, Steve H. Faulkner, and Ruth M. James
lactate. 1 Extracellular buffering mechanisms act to remove these H + from the skeletal muscle cell, but once production rates overwhelm neutralization reactions, the excess H + contribute toward decreasing intramuscular pH. 2 Exercise-induced acidosis inhibits glycolytic energy production and
Grant David Brinkworth, Jonathan David Buckley, Pitre Collier Bourdon, Jason Paul Gulbin, and Adrian Zachei David
A randomized, double-blind, placebo controlled design was used in which 13 elite female rowers, all of whom had competed at World Championships, were supplemented with 60 g · day−1 of either bovine colostrum (BC; n = 6) or concentrated whey protein powder (WP; n = 7) during 9 weeks of pre-competition training. All subjects undertook the study as a group and completed the same training program. Prior to, and after 9 weeks of supplementation and training, subjects completed an incremental rowing test (ROW1) on a rowing ergometer consisting of 3 3 4-min submaximal workloads and a 4-min maximal effort (4max), each separated by a 1-min recovery period. The rowing test was repeated after a 15-min period of passive recovery (ROW2). The 4max for ROW1 provided a measure of performance, and the difference between the 4max efforts of ROW1 and ROW2 provided an index of recovery. Blood lactate concentrations and pH measured prior to exercise and at the end of each workload were used to estimate blood buffer capacity (b). Food intake was recorded daily for dietary analysis. There were no differences in macronutrient intakes (p > .56) or training volumes (p > .99) between BC and WP during the study period. Rowing performance (distance rowed and work done) during 4max of ROW2 was less than ROW1 at baseline (p < .05) but not different between groups (p > .05). Performance increased in both rows by Week 9 (p < .001), with no difference between groups (p > .75). However, the increase was greatest in ROW2 (p < .05), such that by Week 9 there was no longer a difference in performance between the two rows in either group (p > .05). b was not different between groups for ROW1 at baseline (BC 38.3 ± 5.0, WP 38.2 ± 7.2 slykes; p > .05) but was higher in BC by Week 9 (BC 40.8 ± 5.9, WP 33.4 ± 5.3 slykes; p < .05). b for ROW2 followed the same pattern of change as for ROW1. We conclude that supplementation with BC improves b, but not performance, in elite female rowers. It was not possible to determine whether b had any effect on recovery.
Kagan J. Ducker, Brian Dawson, and Karen E. Wallman
Beta-alanine supplementation has been shown to improve exercise performance in short-term high-intensity efforts. However, whether supplementation with beta-alanine is ergogenic to actual sporting events remains unclear and should be investigated in field testing or race simulations.
The aim of this study was to assess if beta-alanine supplementation could improve 2,000-m rowing-ergometer performance in well-trained male rowers.
Participants (N = 16) completed duplicate trials (2 × before supplementation and 2 × after supplementation) of a 2,000-m rowing-ergometer race separated by 28 days of either beta-alanine (n = 7; 80 mg · kg−1 BM · d−1) or placebo (n = 9; glucose) supplementation.
Beta-alanine group (pooled) race times improved by 2.9 ± 4.1 s and placebo group slowed by 1.2 ± 2.9 s, but these results were inconclusive for performance enhancement (p = .055, ES = 0.20, smallest worthwhile change = 49% beneficial). Race split times and average power outputs only significantly improved with beta-alanine at the 750-m (time –0.7 s, p = .01, power +3.6%, p = .03) and 1,000-m (time –0.5 s, p = .01, power +2.9%, p = .02) distances. Blood La− and pH postrace values were not different between groups before or after supplementation.
Overall, 28 d of beta-alanine supplementation with 80 mg · kg−1 BM · d−1 (~7 g/d) did not conclusively improve 2,000-m rowing-ergometer performance in well-trained rowers.
David M. Morris, Rebecca S. Shafer, Kimberly R. Fairbrother, and Mark W. Woodall
The authors sought to determine the effects of oral lactate consumption on blood bicarbonate (HCO3−) levels, pH levels, and performance during high-intensity exercise on a cycle ergometer. Subjects (N = 11) were trained male and female cyclists. Time to exhaustion (TTE) and total work were measured during high-intensity exercise bouts 80 min after the consumption of 120 mg/kg body mass of lactate (L), an equal volume of placebo (PL), or no treatment (NT). Blood HCO3− increased significantly after ingestion of lactate (p < .05) but was not affected in PL or NT (p > .05). No changes in pH were observed as a result of treatment. TTE and total work during the performance test increased significantly by 17% in L compared with PL and NT (p = .02). No significant differences in TTE and total work were seen between the PL and NT protocols (p = .85). The authors conclude that consuming 120 mg/kg body mass of lactate increases HCO3− levels and increases exercise performance during high-intensity cycling ergometry to exhaustion.