The effects of enteric-coated sodium bicarbonate supplementation on 2 km rowing performance in female CrossFit® athletes.

PURPOSE: Sodium bicarbonate (SB) supplementation can improve exercise performance, but few studies consider how effective it is in female athletes. The aim of the study was to establish the effect of individually timed pre-exercise SB ingestion on 2 km rowing time trial (TT) performance in female athletes. METHODS: Eleven female CrossFit® athletes (mean ± SD age, 29 y ± 4 y, body mass, 64.5 kg ± 7.1 kg, height, 1.7 m ± 0.09 m, peak oxygen uptake [VO2peak], 53.8 ± 5.7 mL·kg-1∙min-1). An initial trial identified individual time-to-peak [HCO3-] following enteric-coated 0.3 g·kg-1 BM SB ingestion. Participants then completed a 2 km TT familiarisation followed by a placebo (PLA) or SB trial, using a randomised cross-over design. RESULTS: The ingestion of SB improved rowing performance (514.3 ± 44.6 s) compared to the PLA (529.9 ± 45.4 s) and FAM trials (522.2 ± 43.1 s) (p = 0.001, pη2 = 0.53) which represents a 2.24% improvement compared to the PLA. Individual time-to-peak alkalosis occurred 102.3 ± 22.1 min after ingestion (range 75-150 min) and resulted in increased blood [HCO3-] of 5.5 ± 1.5 mmol⋅L-1 (range = 3.8-7.9 mmol⋅L-1). The change in blood [HCO3-] was significantly correlated with the performance improvement between PLA and SB trials (r = 0.68, p = 0.020). CONCLUSIONS: Ingesting a 0.3 g·kg-1 BM dose of enteric-coated SB improves 2 km rowing performance in female athletes. The improvement is directly related to the extracellular buffering capacity even when blood [HCO3-] does not change ≥ 5.0 mmol⋅L-1.

Single and Serial Carbohydrate Mouth Rinsing Do Not Improve Yo-Yo Intermittent Recovery Test Performance in Soccer Players.

Carbohydrate (CHO) mouth rinsing seems to improve performance in exercises lasting 30-60 min. However, its effects on intermittent exercise are unclear. It is also unknown whether serial CHO mouth rinses can promote additional ergogenic effects when compared with a single mouth rinse. The aim of this study was to evaluate the effect of single and serial CHO mouth rinses on Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance in soccer players. In a randomized, crossover, double-blind, placebo-controlled design, 12 male (18.9 ± 0.5 years) soccer players performed eight serial mouth rinses under three different conditions: placebo solution only (noncaloric juice), seven placebo mouth rinses plus a single CHO mouth rinse (8% maltodextrin), or eight CHO mouth rinses (8-CHO). Following the final mouth rinse, individuals performed the Yo-Yo IR1 test to evaluate the maximal aerobic endurance performance measured via total distance covered. There were no differences in Yo-Yo IR1 performance between sessions (p = .32; single CHO mouth rinse (8% maltodextrin): 1,198 ± 289 m, eight CHO mouth rinses: 1,256 ± 253 m, placebo: 1,086 ± 284 m). In conclusion, single and serial CHO mouth rinsing did not improve performance during the Yo-Yo IR1 for soccer players. These data suggest that CHO mouth rinsing is not an effective ergogenic strategy for intermittent exercise performance irrespective of the number of rinses.

Caffeine Mouth Rinse Does Not Improve Time to Exhaustion in Male Trained Cyclists.

This study investigated the effects of caffeine mouth rinse on cycling time to exhaustion (TTE) and physiological responses in trained cyclists. In a double-blinded randomized counterbalanced cross-over design, 10 recreationally trained male cyclists (mean ± SD: 32 ± 3 years, 72.8 ± 5.3 kg, 1.78 ± 0.06 m, 13.9% ± 3.3% body fat, peak power output = 289.4 ± 24.7 W) completed two TTE tests cycling at 75% of peak aerobic power following 24 hr of dietary and exercise standardization. Cyclists were administered 25-ml mouth rinses for 5 s containing either 85 mg of caffeine or control (water) every 5 min throughout the exercise tests. No significant improvement in TTE was shown with caffeine mouth rinse compared with control (33:24 ± 12:47 vs. 28:08 ± 10:18 min; Cohen's dz effect size: 0.51, p = .14). Caffeine mouth rinse had no significant effect on ratings of perceived exertion (p = .31) or heart rate (p = .35) throughout the cycling TTE protocol. These data indicate that a repeated dose of caffeinated mouth rinse for 5 s does not improve cycling TTE in recreationally trained male cyclists. However, these findings should be taken with caution due to the small sample size and blinding ineffectiveness, while further well-design studies with larger samples are warranted.

Caffeine, CYP1A2 Genotype, and Exercise Performance: A Systematic Review and Meta-analysis.

PURPOSE: This study aimed to summarize and meta-analyze existing evidence regarding the influence of CYP1A2 genotypes on the acute effects of caffeine for exercise performance and to investigate the interaction between genotype, dosage, and timing of caffeine supplementation. METHODS: Six databases were searched for studies determining the effect of caffeine (except mouth rinsing) on exercise performance between CYP1A2 genotypes. Three-level meta-analyses were performed using standardized mean differences (SMD; Hedge's g ) to determine the effect of caffeine on exercise outcomes within and between CYP1A2 genotypes (AA, AC, and CC). Meta-regressions were performed for dose, timing, and presence of reported conflict of interests (RCOI). A meta-analysis was also performed with placebo values to assess for imbalances between genotypes. RESULTS: Thirteen studies, totaling 119 outcomes and 440 participants, were included (233 AA, 175 AC, ad 34 CC). Caffeine improved performance for AA (SMD = 0.30, 95% confidence interval [CI] = 0.21-0.39, P < 0.0001) and AC (SMD = 0.16, 95% CI = 0.06-0.25, P = 0.022) but worsened performance for CC (SMD = -0.22, 95% CI = -0.44 to -0.01, P < 0.0001). Dose affected only CC, with greater doses generating more positive SMD (CC-dose estimate: +0.19/1 mg·kg -1 body mass, 95% CI = 0.04-0.33, P = 0.01). Timing influenced only CC, with better performance with later onset of exercise after supplementation (CC-timing estimate: +0.01/min, 95% CI = 0.00-0.02, P = 0.02). RCOI only affected SMD of CC (CC-RCOI estimate: -0.57, 95% CI = -1.02 to -0.12, P = 0.01). After excluding studies with RCOI, no influence of genotype was seen (all P ≥ 0.19). Small, nonsignificant differences were seen in placebo between genotypes (SMD AA vs CC: -0.13; AA vs AC: -0.12; AC vs CC: -0.05; all P ≥ 0.26). CONCLUSIONS: Caffeine improved performance for AA and AC but worsened performance for CC. Dose and timing moderated the efficacy of caffeine for CC only. Caution is advised because baseline differences and studies with RCOI could have influenced these results.

How Cool is That? The Effects of Menthol Mouth Rinsing on Exercise Capacity and Performance: A Systematic Review and Meta-analysis.

BACKGROUND: Menthol (MEN) mouth rinsing (MR) has gained considerable interest in the athletic population for exercise performance; however, the overall magnitude of effect is unknown. OBJECTIVE: The aim of this systematic review and meta-analysis was to determine the efficacy of menthol MEN MR and the impact it has on exercise capacity and performance. METHODS: Three databases were searched with articles screened according to the inclusion/exclusion criteria. Three-level meta-analyses were used to investigate the overall efficacy of MEN MR and the impact it has on exercise capacity and performance. Meta-regressions were then performed with 1) mean VO2peak, 2) MEN swilling duration; 3) the MEN concentration of MR solution, 4) the number of executed swills throughout a single experiment, 5) the use of flavoured sweetened, non-caloric, or non-flavoured neutral solutions as controls, 6) mean environmental temperature at the time of exercise tests, and 7) exercise type as fixed factors to evaluate their influence on the effects of MEN MR. RESULTS: Ten MEN MR studies included sufficient information pertaining to MEN MR and exercise performance and capacity. MR with MEN resulted in no significant change in capacity and performance (SMD = 0.12; 95% CI - 0.08, 0.31; p = 0.23, n = 1, tau21 < 0.0001, tau22 = < 0.0001, I2 = 0%). No significant influence was detected in meta-regressions for VO2peak, (estimate: 0.03; df = 8; 95% CI - 0.03, 0.09; p = 0.27), swilling duration (5 vs. 10 s: 0.00; df = 16; 95% CI - 0.41, 0.41; p = 1.0), MEN concentration (low [0.01%] vs. high [0.1%]: - 0.08; df = 15; 95% CI - 0.49, 0.32; p = 0.67), number of swills (estimate: 0.02; df = 13; 95% CI - 0.05, 0.09; p = 0.56), the use of flavoured sweetener or non-caloric as control (non-flavoured vs. flavoured: 0.12; df = 16; 95% CI - 0.30, 0.55; p = 0.55) or mean room temperature during exercise tests (estimate: 0.01; df = 16; 95% CI - 0.02, 0.04; p = 0.62). CONCLUSION: MEN MR did not significantly improve overall exercise capacity and performance, though those involved in endurance exercise may see benefits.

The interplay between bicarbonate kinetics and gastrointestinal upset on ergogenic potential after sodium bicarbonate intake: a randomized double-blind placebo-controlled trial.

This double-blind placebo-controlled cross-over study utilized comprehensive monitoring of blood bicarbonate (HCO3¯) kinetics and evaluation of gastrointestinal (GI) upset to determine their impact on an ergogenic potential of sodium bicarbonate (SB) co-ingested with carbohydrate (CHO). Nineteen CrossFit athletes performed 6 bouts of 15 s Wingate Anaerobic Test (WAnT) 90 min post-ingestion of 0.4 g·kg-1 body mass (BM) of SB (SB + CHO treatment) or PLA (PLA + CHO treatment) with 15 g CHO. Blood HCO3¯ concentration was evaluated at baseline, 30-, 60-, 75- and 90 min post-ingestion, in between WAnT bouts, and 3 and 45 min post-exercise, while GI upset at 120 min after protocol started. Control (no supplementation; CTRL) procedures were also performed. An effective elevation of extra-cellular buffering capacity was observed 60-90 min post-ingestion of SB + CHO. At mean peak blood HCO3¯, or at start of exercise an increase > 6 mmol·L-1 in HCO3¯ was noted in 84% and 52.6% participants, respectively. SB + CHO did not prevent performance decrements in WAnT bouts. There were no significant relationships between changes in blood HCO3¯ and WAnTs' performance. Total GI was significantly higher in SB + CHO compared to CTRL, and stomach problems in SB + CHO compared to CTRL and PLA + CHO. There were inverse associations between peak- (p = 0.031; r = - 0.495), average- (p = 0.002; r = - 0.674) and minimum power (p = 0.008; r = - 0.585) and total GI upset, as well as average power and severe GI distress (p = 0.042; r = - 0.471) at SB + CHO. The implemented dose of SB + CHO was effective in improving buffering capacity, but did not prevent decrements in WAnTs' performance. GI side effects were crucial in affecting the ergogenic potential of SB and thus must be insightfully monitored in future studies.

Acute caffeine mouth rinsing does not improve 10-km running performance in CYP1A2 C-allele carriers.

PURPOSE: This study assessed whether caffeine mouth rinsing affects 10-km run performance and vertical jump in recreational runners. METHODS: A double-blind, placebo-controlled, crossover study was conducted. Ten well-trained volunteers performed two trials, following caffeine or placebo mouth rinse, separated by seven days. Immediately before the 10-km run, a 10-second mouth rinse with either 300 mg of caffeine (1.2%) or microcrystalline cellulose (placebo) diluted in 25 mL of water was performed. Pre- and post-exercise, participants performed a vertical jump test. A Garmin Forerunner® GPS, was used to measure 10-km running time and an 11-point Borg scale was used post-exercise to measure ratings of perceived exertion. Blood samples were also collected during the visit in the laboratory in the afternoon period to classify individuals according to their CYP1A2 genotype. Vertical jump performance was evaluated using a force plate. RESULTS: Nine runners (90%) were CC homozygotes and one (10%) was an AC heterozygote for CYP1A2. There was no difference in 10-km time-trial performance (Placebo: 47.07 ± 5.18 vs. CAF: 47.45 ± 6.34 min, p = 0.89), ratings of perceived exertion (Placebo: 17 ± 1 vs. CAF: 16 ± 2, p = 0.34) or vertical jump power (Placebo, Pre: 4.5 ± 0.6 W•kg-1 and Post: 4.5 ± 0.7 W•kg-1; CAF: Pre: 4.4 ± 0.7 W•kg-1 and Post: 4.4 ± 0.8 W•kg-1, d = 0.21, p = 0.66) between trials. CONCLUSION: Acute caffeine mouth rinsing (1.2%) did not improve 10-km performance and showed similar null effects on vertical jump performance in CYP1A2 C-allele carriers.