Sodium bicarbonate ingestion and boxing performance

Boxing is a sport that consists of multiple high-intensity bouts separated by minimal recovery time and may benefit from a pre-exercise alkalotic state. The purpose of this study was to observe the ergogenic potential of sodium bicarbonate (NaHCO3) ingestion on boxing performance. Ten amateur boxers volunteered to participate in 2 competitive sparring bouts. The boxers were prematched for weight and boxing ability and consumed either 0.3 g·kg−1 body weight (BW) of NaHCO3 (BICARB) or 0.045 g·kg−1 BW of NaCl placebo (PLAC) mixed in diluted low calorie-flavored cordial. The sparring bouts consisted of four 3-minute rounds, each separated by 1-minute seated recovery. Blood acid-base (pH, bicarbonate [HCO3−], base excess [BE]), and performance (rates of perceived exertion [RPE], heart rate [HR] [HRave and HRmax], total punches landed successfully) profiles were analyzed before (where applicable) and after sparring. The results indicated a significant interaction effect for HCO3− (p ≤ 0.001) and BE (p < 0.001), but not for pH (p = 0.48). Post hoc analysis revealed higher presparring HCO3− and BE for the BICARB condition, but no differences between the BICARB and PLAC conditions postsparring. There was a significant increase in punches landed during the BICARB condition (p < 0.001); however, no significant interaction effects for HRave (p = 0.15), HRmax (p = 0.32), or RPE (p = 0.38). The metabolic alkalosis induced by the NaHCO3 loading elevated before and after sparring blood buffering capacity. In practical application, the findings suggest that a standard NaHCO3 loading dose (0.3 g·kg−1) improves punch efficacy during 4 rounds of sparring performance

Sodium bicarbonate ingestion and repeated swim sprint performance

The purpose of the present investigation was to observe the ergogenic potential of 0.3 g.kg^sup -1^ of sodium bicarbonate (NaHCO^sub 3^) in competitive, nonelite swimmers using a repeated swim sprint design that eliminated the technical component of turning. Six male (181.2 ± 7.2 cm; 80.3 ± 11.9 kg; 50.8 ± 5.5 ml.kg^sup -1^.min^sup -1^ VO^sub 2^max) and 8 female (168.8 ± 5.6 cm; 75.3 ± 10.1 kg; 38.8 ± 2.6 ml.kg^sup -1^.min^sup -1^ VO^sub 2^max) swimmers completed 2 trial conditions (NaHCO^sub 3^ [BICARB] and NaCl placebo [PLAC]) implemented in a randomized (counterbalanced), single blind manner, each separated by 1 week. Swimmers were paired according to ability and completed 8, 25-m front crawl maximal effort sprints each separated by 5 seconds. Blood acid-base status was assessed preingestion, pre, and postswim via capillary finger sticks, and total swim time was calculated as a performance measure. Total swim time was significantly decreased in the BICARB compared to PLAC condition (p = 0.04), with the BICARB condition resulting in a 2% decrease in total swim time compared to the PLAC condition (159.4 ± 25.4 vs. 163.2 ± 25.6 seconds; mean difference = 4.4 seconds; 95% confidence interval = 8.7-0.1). Blood analysis revealed significantly elevated blood buffering potential preswim (pH; BICARB = 7.48 ± 0.01, PLAC = 7.41 ± 0.01) along with a significant decrease in extracellular K+ (BICARB = 4.0 ± 0.1 mmol.L^sup -1^, PLAC = 4.6 ± 0.1 mmol.L^sup -1^). The findings suggest that 0.3 g.kg^sup -1^ NaHCO^sub 3^ ingested 2.5 hours before exercise enhances the blood buffering potential and may positively influence swim performance. Note: Some of the scientific symbols cannot be represented correctly in the abstract. Please read with caution and refer to the original publication

Practical recommendations for coaches and athletes : a meta-analysis of sodium bicarbonate use for athletic performance

Sodium bicarbonate (NaHCO3) is a buffering agent that is suggested to improve performance by promoting the efflux of hydrogen ions from working cells and tissues. Research surrounding its efficacy as an ergogenic aid is conflicting, making it difficult to draw conclusions as to its effectiveness for training and competition. This study performed a meta-analysis of relevant research articles to allow the development of concise practical recommendations for coaches and athletes. The overall effect size for the influence of NaHCO3 on performance was moderate, and was significantly lower for specifically trained as opposed to recreationally trained participants

The effect of metabolic alkalosis on central and peripheral mechanisms associated with exercise-induced muscle fatigue in humans

The increased concentration of protons during fatiguing exercise may contribute to increased activation of group III and IV afferents and subsequently reduced central drive, however this has yet to be confirmed in exercising humans. Here we determined whether inducing metabolic alkalosis differentially effects descending central drive following fatiguing exercise, and whether this effect may, in part, be explained by attenuating group III and IV afferent firing. 11 males performed a maximal 2 min voluntary knee extension (MVC) followed by a 2 min rest and subsequent 1 min MVC with an occlusive cuff either under placebo (PLA; 0.3 g·kg-1 BW calcium carbonate) or alkalosis (ALK; 0.3 g·kg-1 BW sodium bicarbonate) condition. Femoral nerve stimulation was applied prior to exercise, after the 2 min MVC and then at 40 to 60 s intervals throughout the remainder of the protocol to explore central and peripheral mechanisms associated with reductions in maximum force and rate of torque development. Although voluntary activation (VA) declined similarly after the 2 min MVC, during the ischemic period VA was higher during ALK (PLA: 57 ± 8%; ALK: 76 ± 5%). Maximal voluntary torque declined at similar rates during the task (203 ± 19 Nm), however maximal rate of torque development was significantly higher in the ALK condition after the 2 min MVC (mean difference of 177 ± 60 Nm·s-1 ). These results demonstrate the effect of pH on voluntary activation as well as maximal rates of torque development after sustained, maximal voluntary knee extension in humans

Sodium bicarbonate supplementation minimally affects the accumulated oxygen deficit during intense cycling to exhaustion

The aim of this investigation was to test whether sodium bicarbonate (NaHCO3) affects the anaerobic energy contribution during a high-intensity cycling task. Eight participants (mean ± SD; age 25 ± 4 years) completed 4 different testing sessions separated by at least 48 hours. During the first 2 sessions, participants performed a series of intermittent bouts of 5 minutes submaximal steady-state cycling and responses were used to calculate the VO2-power regression and estimate the O2 demand of high-intensity cycling. In the final 2 sessions under either a control (PLA = 0.3 g·kg-1 body mass calcium carbonate) or experimental condition (ALK = 0.3 g·kg-1 body mass NaHCO3), participants cycled at 125% VO2peak to volitional exhaustion during which VO2 was measured and the accumulated O2 uptake and O2 deficit were estimated. Times to volitional exhaustion during high-intensity cycling did not differ significantly between ALK (101.3 ± 20.2 seconds) and PLA (98.7 ± 21.4 seconds), and alkalosis did not significantly affect the AOD (ALK: 44.8 ± 10.8 mL·kg-1) and PLA (44.2 ± 12.8 mL·kg-1; P = .82). As such, we would conclude that anaerobic capacity during short-term, high-intensity exercise is minimally affected by metabolic alkalosis induced by NaHCO3 supplementation

Lower hamstring extensibility in men compared to women is explained by differences in stretch tolerance

Background: This study examined whether passive hamstring tissue stiffness and/or stretch tolerance explain the relationship between sex and hamstring extensibility. Methods: Ninety healthy participants, 45 men and 45 women (mean ± SD; age 24.6 ± 5.9 years, height 1.72 ± 0.09 m, weight 74.6 ± 14.1 kg) volunteered for this study. The instrumented straight leg raise was used to determine hamstring extensibility and allow measurement of stiffness and stretch tolerance (visual analog pain score, VAS). Results: Hamstring extensibility was 9.9° greater in women compared to men (p = 0.003). VAS scores were 16 mm lower in women (p = 0.001). Maximal stiffness (maximal applied torque) was not different between men and women (p = 0.42). Passive stiffness (slope from 20-50° hip flexion) was 0.09 Nm.°-1 lower in women (p = 0.025). For women, linear and stepwise regression showed that no predictor variables were associated with hamstring extensibility (adjusted r2 = -0.03, p = 0.61). For men, 44% of the variance in hamstring extensibility was explained by VAS and maximal applied torque (adjusted r2 = 0.44, p < 0.001), with 41% of the model accounted for by the relationship between higher VAS scores and lower extensibility (standardized β coefficient = -0.64, p < 0.001). Conclusions: The results of this study suggest that stretch tolerance and not passive stiffness explains hamstring extensibility, but this relationship is only manifest in men

[In Press] Mouth rinsing and ingesting salty or bitter solutions does not influence corticomotor excitability or neuromuscular function

Purpose To explore the efect of tasting unpleasant salty or bitter solutions on lower limb corticomotor excitability and neuromuscular function. Methods Nine females and eleven males participated (age: 27±7 years, BMI: 25.3±4.0 kg m−2). Unpleasant salty (1 M) and bitter (2 mM quinine) solutions were compared to water, sweetened water, and no solution, which functioned as control conditions. In a non-blinded randomized cross-over order, each solution was mouth rinsed (10 s) and ingested before perceptual responses, instantaneous heart rate (a marker of autonomic nervous system activation), quadricep corticomotor excitability (motor-evoked potential amplitude) and neuromuscular function during a maximal voluntary contraction (maximum voluntary force, resting twitch force, voluntary activation, 0–50 ms impulse, 0–100 impulse, 100–200 ms impulse) were measured. Results Hedonic value (water: 47±8%, sweet: 23±17%, salt: 71±8%, bitter: 80±10%), taste intensity, unpleasantness and increases in heart rate (no solution: 14±5 bpm, water: 18±5 bpm, sweet: 20±5 bpm, salt: 24±7 bpm, bitter: 23±6 bpm) were signifcantly higher in the salty and bitter conditions compared to control conditions. Nausea was low in all conditions (<15%) but was signifcantly higher in salty and bitter conditions compared to water (water: 3±5%, sweet: 6±13%, salt: 7±9%, bitter: 14±16%). There was no signifcant diference between conditions in neuromuscular function or corticomotor excitability variables. Conclusion At rest, unpleasant tastes appear to have no infuence on quadricep corticomotor excitability or neuromuscular function. These data question the mechanisms via which unpleasant tastes are proposed to infuence exercise performance

A new pathway to approximate energy expenditure and recovery of an athlete

This work proposes to use evolutionary computation as a pathway to allow a new perspective on the modeling of energy expenditure and recovery of an individual athlete during exercise. We revisit a theoretical concept called the "three component hydraulic model" which is designed to simulate metabolic systems during exercise and which is able to address recently highlighted shortcomings of currently applied performance models. This hydraulic model has not been entirely validated on individual athletes because it depends on physiological measures that cannot be acquired in the required precision or quantity. This paper introduces a generalized interpretation and formalization of the three component hydraulic model that removes its ties to concrete metabolic measures and allows to use evolutionary computation to fit its parameters to an athlete

Changes in passive tension of the hamstring muscles during a simulated soccer match

Passive muscle tension is increased following damaging eccentric exercise. Hamstring strain injury is associated with damaging eccentric muscle actions, but no research has examined changes in hamstring passive muscle tension throughout a simulated sport activity. We measured hamstring passive tension throughout a 90-minute simulated soccer match, including the warm-up period, and every 15-minutes throughout the 90-minute simulation.Passive hamstring tension of fifteen amateur male soccer players was measured using the instrumented straight leg raise test. Absolute torque (Nm) and slope (Nm.°-1) of the recorded torque-angular position curve were used for data analysis, in addition to total leg range of motion. Players performed a 15-minute pre-match warm-up, then performed the 90-minute soccer simulation (SAFT90) including a 15-minute half-time rest period.Reductions in passive stiffness from 20 to 50° of passive hip flexion between 22.1 to 29.2% (p<0.05) were observed after the warm-up period. During the SAFT90 passive tension increased in the latter 20% of the range of motion between 10.1 to 10.9% (p<0.05) concomitant to a 4.5% increase in total hamstring range of motion (p=0.0009).The findings of this study imply that hamstring passive tension is reduced following an active warm-up that includes dynamic stretching, but does not increase in a pattern suggestive of eccentric induced muscle damage during soccer-specific intermittent exercise. Hamstring range of motion and passive tension increases are best explained by improved stretch tolerance