Search Results

Purpose: To identify the period prevalence of hormonal contraceptive (HC) use and characterize the perceived side effects associated with the menstrual cycle and HC use. Methods: A total of 430 elite female athletes completed a questionnaire to assess the period prevalence of HC use, the reasons for initiation and discontinuation of HCs, and the side effects experienced by HC and non-HC users. Descriptive statistics, between-groups comparisons, and associations between categorical variables were calculated. Results : Of athletes studied, 49.5% were currently using HCs and 69.8% had used HCs at some point. Combined oral contraceptives were most commonly used (68.1%), with 30.0% using progestin-only contraceptives (implant = 13.1%, injection = 3.7%, and intrauterine system = 2.8%). Perceived negative side effects were more common with progestin-only HC use (39.1%) compared with combined-HC use (17.8%; P = .001) and were most prevalent in implant users (53.6%; P = .004). HC users reported perceived positive side effects relating to their ability to predict and/or manipulate the timing, frequency, and amount of menstrual bleeding. Non-HC users had a menstrual cycle length of 29 (5) d and 77.4% reported negative side effects during their menstrual cycle, primarily during days 1–2 of menstruation (81.6%). Conclusions: Approximately half of elite athletes used HCs, and progestin-only contraceptive users reported greater incidences of negative side effects, especially with the implant. Because of the high interindividual variability in reported side effects, athletes and practitioners should maintain an open dialogue to pursue the best interests of the athlete.

To defend against hydrogen cation accumulation and muscle fatigue during exercise, sodium bicarbonate (NaHCO₃) ingestion is commonplace. The individualized dose-response relationship between NaHCO₃ ingestion and blood biochemistry is unclear. The present study investigated the bicarbonate, pH, base excess and sodium responses to NaHCO₃ ingestion. Sixteen healthy males (23 ± 2 years; 78.6 ± 15.1 kg) attended three randomized order-balanced, nonblinded sessions, ingesting a single dose of either 0.1, 0.2 or 0.3 g·kg^-1BM of NaHCO₃ (Intralabs, UK). Fingertip capillary blood was obtained at baseline and every 10 min for 1 hr, then every 15 min for a further 2 hr. There was a significant main effect of both time and condition for all assessed blood analytes (p ≤ .001). Blood analyte responses were significantly lower following 0.1 g·kg^-1BM compared with 0.2 g·kg^-1BM; bicarbonate concentrations and base excess were highest following ingestion of 0.3 g·kg^-1BM (p ≤ .01). Bicarbonate concentrations and pH significantly increased from baseline following all doses; the higher the dose the greater the increase. Large interindividual variability was shown in the magnitude of the increase in bicarbonate concentrations following each dose (+2.0–5; +5.1–8.1; and +6.0–12.3 mmol·L^-1 for 0.1, 0.2 and 0.3 g·kg^-1BM) and in the range of time to peak concentrations (30–150; 40–165; and 75–180 min for 0.1, 0.2 and 0.3 g·kg^-1BM). The variability in bicarbonate responses was not affected by normalization to body mass. These results challenge current practices relating to NaHCO₃ supplementation and clearly show the need for athletes to individualize their ingestion protocol and trial varying dosages before competition.

This study determined the influence of a high- (HI) versus low-intensity (LI) cycling warm-up on blood acid-base responses and exercise capacity following ingestion of sodium bicarbonate (SB; 0.3 g/kg body mass) or a placebo (PLA; maltodextrin) 3 hr prior to warm-up. Twelve men (21 ± 2 years, 79.2 ± 3.6 kg body mass, and maximum power output [W _max] 318 ± 36 W) completed a familiarization and four double-blind trials in a counterbalanced order: HI warm-up with SB, HI warm-up with PLA, LI warm-up with SB, and LI warm-up with PLA. LI warm-up was 15 min at 60% W _max, while the HI warm-up (typical of elites) featured LI followed by 2 × 30 s (3-min break) at W _max, finishing 30 min prior to a cycling capacity test at 110% W _max. Blood bicarbonate and lactate were measured throughout. SB supplementation increased blood bicarbonate (+6.4 mmol/L; 95% confidence interval, CI [5.7, 7.1]) prior to greater reductions with HI warm-up (−3.8 mmol/L; 95% CI [−5.8, −1.8]). However, during the 30-min recovery, blood bicarbonate rebounded and increased in all conditions, with concentrations ∼5.3 mmol/L greater with SB supplementation (p < .001). Blood bicarbonate significantly declined during the cycling capacity test at 110%W _max with greater reductions following SB supplementation (−2.4 mmol/L; 95% CI [−3.8, −0.90]). Aligned with these results, SB supplementation increased total work done during the cycling capacity test at 110% W _max (+8.5 kJ; 95% CI [3.6, 13.4], ∼19% increase) with no significant main effect of warm-up intensity (+0.0 kJ; 95% CI [−5.0, 5.0]). Collectively, the results demonstrate that SB supplementation can improve HI cycling capacity irrespective of prior warm-up intensity, likely due to blood alkalosis.

The ability to buffer H⁺ could be vital to exercise performance, as high concentrations of H⁺ contribute to the development of fatigue.

Currently, little is known about the extent of interindividual variability in response to beta-alanine (BA) supplementation, nor what proportion of said variability can be attributed to external factors or to the intervention itself (intervention response). To investigate this, individual participant data on the effect of BA supplementation on a high-intensity cycling capacity test (CCT_110%) were meta-analyzed. Changes in time to exhaustion (TTE) and muscle carnosine were the primary and secondary outcomes. Multilevel distributional Bayesian models were used to estimate the mean and SD of BA and placebo group change scores. The relative sizes of group SDs were used to infer whether observed variation in change scores were due to intervention or non-intervention-related effects. Six eligible studies were identified, and individual data were obtained from four of these. Analyses showed a group effect of BA supplementation on TTE (7.7, 95% credible interval [CrI] [1.3, 14.3] s) and muscle carnosine (18.1, 95% CrI [14.5, 21.9] mmol/kg DM). A large intervention response variation was identified for muscle carnosine (σ_IR = 5.8, 95% CrI [4.2, 7.4] mmol/kg DM) while equivalent change score SDs were shown for TTE in both the placebo (16.1, 95% CrI [13.0, 21.3] s) and BA (15.9, 95% CrI [13.0, 20.0] s) conditions, with the probability that SD was greater in placebo being 0.64. In conclusion, the similarity in observed change score SDs between groups for TTE indicates the source of variation is common to both groups, and therefore unrelated to the supplement itself, likely originating instead from external factors such as nutritional intake, sleep patterns, or training status.