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.
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.
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
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.
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.
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
Lewis A. Gough, Steven Rimmer, Callum J. Osler, and Matthew F. Higgins
This study evaluated the ingestion of sodium bicarbonate (NaHCO3) on postexercise acid-base balance recovery kinetics and subsequent high-intensity cycling time to exhaustion. In a counterbalanced, crossover design, nine healthy and active males (age: 23 ± 2 years, height: 179 ± 5 cm, body mass: 74 ± 9 kg, peak mean minute power (Wpeak) 256 ± 45 W, peak oxygen uptake (V̇O2peak) 46 ± 8 ml.kg-1.min-1) performed a graded incremental exercise test, two familiarization and two experimental trials. Experimental trials consisted of cycling to volitional exhaustion (TLIM1) at 100% WPEAK on two occasions (TLIM1 and TLIM2) interspersed by a 90 min passive recovery period. Using a double-blind approach, 30 min into a 90 min recovery period participants ingested either 0.3 g.kg-1 body mass sodium bicarbonate (NaHCO3) or a placebo (PLA) containing 0.1 g.kg-1 body mass sodium chloride (NaCl) mixed with 4 ml.kg-1 tap water and 1 ml.kg-1 orange squash. The mean differences between TLIM2 and TLIM1 was larger for PLA compared with NaHCO3 (-53 ± 53 vs. -20 ± 48 s; p = .008, d = 0.7, CI =-0.3, 1.6), indicating superior subsequent exercise time to exhaustion following NaHCO3. Blood lactate [Bla-] was similar between treatments post TLIM1, but greater for NaHCO3 post TLIM2 and 5 min post TLIM2. Ingestion of NaHCO3 induced marked increases (p < .01) in both blood pH (+0.07 ± 0.02, d = 2.6, CI = 1.2, 3.7) and bicarbonate ion concentration [HCO3 -] (+6.8 ± 1.6 mmo.l-1, d = 3.4, CI = 1.8, 4.7) compared with the PLA treatment, before TLIM2. It is likely both the acceleration of recovery, and the marked increases of acid-base after TLIM1 contributed to greater TLIM2 performance compared with the PLA condition.
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.
The aim of this study was to assess if beta-alanine supplementation could improve 800 m track running performance in male recreational club runners (n = 18).
Participants completed duplicate trials (2 presupplementation, 2 postsupplementation) of an 800 m race, separated by 28 days of either beta-alanine (n = 9; 80 mg·kg−1BM·day−1) or placebo (n = 9) supplementation.
Using ANCOVA (presupplementation times as covariate), postsupplementation race times were significantly faster following beta-alanine (p = .02), with post- versus presupplementation race times being faster after beta-alanine (–3.64 ± 2.70 s, –2.46 ± 1.80%) but not placebo (–0.59 ± 2.54 s, –0.37 ± 1.62%). These improvements were supported by a moderate effect size (d = 0.70) and a very likely (99%) benefit in the beta-alanine group after supplementation. Split times (ANCOVA) at 400 m were significantly faster (p = .02) postsupplementation in the beta-alanine group, compared with placebo. This was supported by large effect sizes (d = 1.05–1.19) and a very likely (99%) benefit at the 400 and 800 m splits when comparing pre- to postsupplementation with beta-alanine. In addition, the first and second halves of the race were faster post- compared with presupplementation following beta-alanine (1st half –1.22 ± 1.81 s, likely 78% chance of benefit; 2nd half –2.38 ± 2.31 s, d = 0.83, very likely 98% chance of benefit). No significant differences between groups or pre- and postsupplementation were observed for postrace blood lactate and pH.
Overall, 28 days of beta-alanine supplementation (80 mg·kg-1BM·day-1) improved 800 m track performance in recreational club runners.