Matthew F. Higgins

The effects of sodium bicarbonate (NaHCO3) ingestion on high intensity cycling capacity

Abstract Ten healthy, non-cycling trained males (age: 21.2 ± 2.2 years, body mass: 75.9 ± 13.4 kg, height: 178 ± 6 cm, [Vdot]O2PEAK: 46 ± 10 ml · kg−1 · min−1) performed a graded incremental exercise test, two familiarisation trials and six experimental trials. Experimental trials consisted of cycling to volitional exhaustion at 100%, 110% and 120% WPEAK, 60 min after ingesting either 0.3 g · kg−1 body mass sodium bicarbonate (NaHCO3) or 0.1 g · kg−1 body mass sodium chloride (placebo). NaHCO3 ingestion increased cycling capacity by 17% at 100% WPEAK (327 vs. 383 s; P = 0.02) although not at 110% WPEAK (249 vs. 254 s; P = 0.66) or 120% WPEAK (170 vs. 175 s; P = 0.60; placebo and NaHCO3 respectively). Heart rate (P = 0.02), blood lactate (P = 0.001), pH (P < 0.001), [HCO3 −], (P < 0.001), and base excess (P < 0.001) were greater in all NaHCO3 trials. NaHCO3 attenuated localised ratings of perceived exertion (RPEL) to a greater extent than placebo only at 100% WPEAK (P < 0.02). Ratings of abdominal discomfort and gut fullness were mild but higher for NaHCO3. NaHCO3 ingestion significantly improves continuous constant load cycling at 100% WPEAK due to, in part, attenuation of RPEL.

Does a physiological concentration of taurine increase acute muscle power output, time to fatigue, and recovery in isolated mouse soleus (slow) muscle with or without the presence of caffeine?

High concentrations of caffeine and taurine are key constituents of many ergogenic supplements ingested acutely to provide legal enhancements in athlete performance. Despite this, there is little evidence supporting the claims for the performance-enhancing effects of acute taurine supplementation. In-vitro models have demonstrated that a caffeine-induced muscle contracture can be further potentiated when combined with a high concentration of taurine. However, the high concentrations of caffeine used in previous research would be toxic for human consumption. Therefore, this study aimed to investigate whether a physiological dose of caffeine and taurine would directly potentiate skeletal muscle performance. Isolated mouse soleus muscle was used to examine the effects of physiological taurine (TAU), caffeine (CAF), and taurine-caffeine combined (TC) on (i) acute muscle power output; (ii) time to fatigue; and (iii) recovery from fatigue, compared with the untreated controls (CON). Treatment with TAU failed to elicit any significant difference in the measured parameters. Treatment with TC resulted in a significant increase in acute muscle power output and faster time to fatigue. The ergogenic benefit posed by TC was not different from the effects of caffeine alone, suggesting no acute ergogenic benefit of taurine.

Evaluating the effects of caffeine and sodium bicarbonate, ingested individually or in combination, and a taste-matched placebo on high-intensity cycling capacity in healthy males

This study evaluated the effects of ingesting sodium bicarbonate (NaHCO3) or caffeine individually or in combination on high-intensity cycling capacity. In a counterbalanced, crossover design, 13 healthy, noncycling trained males (age: 21 ± 3 years, height: 178 ± 6 cm, body mass: 76 ± 12 kg, peak power output (Wpeak): 230 ± 34 W, peak oxygen uptake: 46 ± 8 mL·kg(-1)·min(-1)) performed a graded incremental exercise test, 2 familiarisation trials, and 4 experimental trials. Trials consisted of cycling to volitional exhaustion at 100% Wpeak (TLIM) 60 min after ingesting a solution containing either (i) 0.3 g·kg(-1) body mass sodium bicarbonate (BIC), (ii) 5 mg·kg(-1) body mass caffeine plus 0.1 g·kg(-1) body mass sodium chloride (CAF), (iii) 0.3 g·kg(-1) body mass sodium bicarbonate plus 5 mg·kg(-1) body mass caffeine (BIC-CAF), or (iv) 0.1 g·kg(-1) body mass sodium chloride (PLA). Experimental solutions were administered double-blind. Pre-exercise, at the end of exercise, and 5-min postexercise blood pH, base excess, and bicarbonate ion concentration ([HCO3(-)]) were significantly elevated for BIC and BIC-CAF compared with CAF and PLA. TLIM (median; interquartile range) was significantly greater for CAF (399; 350-415 s; P = 0.039; r = 0.6) and BIC-CAF (367; 333-402 s; P = 0.028; r = 0.6) compared with BIC (313: 284-448 s) although not compared with PLA (358; 290-433 s; P = 0.249, r = 0.3 and P = 0.099 and r = 0.5, respectively). There were no differences between PLA and BIC (P = 0.196; r = 0.4) or between CAF and BIC-CAF (P = 0.753; r = 0.1). Relatively large inter- and intra-individual variation was observed when comparing treatments and therefore an individual approach to supplementation appears warranted.

The effects of 8 weeks voluntary wheel running on the contractile performance of isolated locomotory (soleus) and respiratory (diaphragm) skeletal muscle during early ageing.

ABSTRACT Decreased skeletal muscle performance with increasing age is strongly associated with reduced mobility and quality of life. Increased physical activity is a widely prescribed method of reducing the detrimental effects of ageing on skeletal muscle contractility. The present study used isometric and work loop testing protocols to uniquely investigate the effects of 8 weeks of voluntary wheel running on the contractile performance of isolated dynapenic soleus and diaphragm muscles of 38-week-old CD1 mice. When compared with untrained controls, voluntary wheel running induced significant improvements in maximal isometric stress and work loop power, a reduced resistance to fatigue, but greater cumulative work during fatiguing work loop contractions in isolated muscle. These differences occurred without appreciable changes in lactate dehydrogenase, citrate synthase, sarco-endoplasmic reticulum ATPase or myosin heavy chain expression synonymous with this form of training in younger rodent models. Despite the given improvement in contractile performance, the average running distance significantly declined over the course of the training period, indicating that this form of training may not be sufficient to fully counteract the longer-term ageing-induced decline in skeletal muscle contractile performance. Although these results indicate that regular low-intensity physical activity may be beneficial in offsetting the age-related decline in skeletal muscle contractility, future work focusing on the maintenance of a healthy body mass with increasing age and its effects on myosin-actin cross-bridge kinetics and Ca2+ handling is needed to clarify the mechanisms causing the improved contractile performance in trained dynapenic skeletal muscle. Summary: Although regular low-intensity physical activity may be beneficial in offsetting age-related decline in skeletal muscle contractility, future work is needed to clarify the mechanisms causing the improved contractile performance in trained dynapenic skeletal muscle.

Expectancy of ergogenicity from sodium bicarbonate ingestion increases high-intensity cycling capacity

This study examined whether expectancy of ergogenicity of a commonly used nutritional supplement (sodium bicarbonate; NaHCO3) influenced subsequent high-intensity cycling capacity. Eight recreationally active males (age, 21 ± 1 years; body mass, 75 ± 8 kg; height, 178 ± 4 cm; WPEAK = 205 ± 22 W) performed a graded incremental test to assess peak power output (WPEAK), one familiarisation trial and two experimental trials. Experimental trials consisted of cycling at 100% WPEAK to volitional exhaustion (TLIM) 60 min after ingesting either a placebo (PLA: 0.1 g·kg(-1) sodium chloride (NaCl), 4 mL·kg(-1) tap water, and 1 mL·kg(-1) squash) or a sham placebo (SHAM: 0.1 g·kg(-1) NaCl, 4 mL·kg(-1) carbonated water, and 1 mL·kg(-1) squash). SHAM aimed to replicate the previously reported symptoms of gut fullness (GF) and abdominal discomfort (AD) associated with NaHCO3 ingestion. Treatments were administered double blind and accompanied by written scripts designed to remain neutral (PLA) or induce expectancy of ergogenicity (SHAM). After SHAM mean TLIM increased by 9.5% compared to PLA (461 ± 148 s versus 421 ± 150 s; P = 0.048, d = 0.3). Ratings of GF and AD were mild but ~1 unit higher post-ingestion for SHAM. After 3 min TLIM overall ratings of perceived exertion were 1.4 ± 1.3 units lower for SHAM compared to PLA (P = 0.020, d = 0.6). There were no differences between treatments for blood lactate, blood glucose, or heart rate. In summary, ergogenicity after NaHCO3 ingestion may be influenced by expectancy, which mediates perception of effort during subsequent exercise. The observed ergogenicity with SHAM did not affect our measures of cardiorespiratory physiology or metabolic flux.

An exercise-induced improvement in isolated skeletal muscle contractility does not affect the performance-enhancing benefit of 70μM caffeine treatment.

ABSTRACT This study aimed to examine the effects of exercise-induced increases in skeletal muscle contractile performance on isolated skeletal muscle caffeine sensitivity in mice. CD1 mice (n=28; 30 weeks old) either served as controls or underwent 8 weeks of voluntary wheel running. Following the treatment intervention, whole soleus (SOL) or a section of the costal diaphragm (DIA) was isolated from each mouse and tested to determine the effect of 70 µmol l−1 caffeine on work loop power output. Although caffeine elicited a significant increase in power of both the SOL and the DIA relative to levels in a non-caffeine-treated control, the effect was not different between the experimental groups, despite the muscles of the trained group producing significantly greater muscle power. There was no significant relationship between training volume or baseline work loop power and the caffeine response. These results indicate that an exercise-induced increase in muscle performance did not influence the performance-enhancing effects of caffeine. Summary: The performance-enhancing effect of caffeine is not improved following exercise training as shown by assessing the effects of 70 µmol l−1 caffeine on muscle isolated from trained and untrained mice.

The influence of caffeine expectancies on sport, exercise and cognitive performance.

Caffeine (CAF) is widely consumed across sport and exercise for its reputed ergogenic properties, including central nervous stimulation and enhanced muscular force development. However, expectancy and the related psychological permutations that are associated with oral CAF ingestion are generally not considered in most experimental designs and these could be important in understanding if/how CAF elicits an ergogenic effect. The present paper reviews 17 intervention studies across sport, exercise, and cognitive performance. All explore CAF expectancies, in conjunction with/without CAF pharmacology. Thirteen out of 17 studies indicated expectancy effects of varying magnitudes across a range of exercise tasks and cognitive skills inclusive off but not limited to; endurance capacity, weightlifting performance, simple reaction time and memory. Factors, such as motivation, belief, and habitual CAF consumption habits influenced the response. In many instances, these effects were comparable to CAF pharmacology. Given these findings and the lack of consistency in the experimental design, future research acknowledging factors, such as habitual CAF consumption habits, habituated expectations, and the importance of subjective post-hoc analysis will help to advance knowledge within this area.

Deep ocean minerals minimize eccentric exercise-induced inflammatory response of rat skeletal muscle.

Background: We have previously shown an accelerated recovery from muscle fatigue in men challenged by prolonged exercise after oral deep ocean minerals (DOM) supplementation. Here, we hypothesized a decrease in eccentric exercise-induced muscle inflammation in rats regularly consuming DOM-containing drinks (hardness 600 mg/L and fructose 11%). Methods: Forty-seven male Sprague Dawley rats were randomized into 4 groups: Control (C, N = 12), Fructose (F, N = 12), Fructose+Exercise (FE, N = 12), and Fructose+Exercise+DOM (FED, N = 11). Since fructose is a commonly used ingredient in beverages, 11% of fructose was added as a vehicle of the study. Soleus muscles of rats were analyzed 24 h after an acute bout of downhill running following 9 weeks of DOM supplementation. Results: Leukocyte infiltration and TNF-α mRNA of muscle in the FE group were 5 times and 4 times greater the F group, respectively, (P < 0.05). Both markers in the FED group were significantly lower than those in the FE group (P < 0.05). IL-10 mRNA of muscle in the F group was >eight fold greater than the C group (P < 0.05). The reduced glutathione (GSH) of muscle in the F group was 34% lower than that in the C group (P < 0.05). However, GSH levels were similar for the C and FED groups. Conclusion: Prolonged fructose supplementation modulates inflammatory balance of rat skeletal muscle. The results of the study suggest that DOM can minimize eccentric exercise-induced inflammatory cytokine responses in rat skeletal muscle.

Quantification of bowling workload and changes in cognitive function in elite fast bowlers in training compared with twenty20 cricket.

BACKGROUND Bowling overs are the primary recorded measure for workloads in cricket for youth through to professionals. However, the validity of this measure has never been tested. Additionally, despite the cognitive component of cricket being suggested to be very high, changes in psychomotor processing speed has again not been explored. METHODS Eight professional English county cricket bowlers participated in the study. Participants wore global positioning systems with a tri-axial accelerometer during a Twenty20 match and training. Bowling overs were expressed relative to external forces. Additionally, cognitive function (as measured by psychomotor speed) was assessed pre and post Twenty20 game and training. RESULTS When expressed relative to high intensity running distance or external forces from the tri-axial accelerometer, the cost of each over (6 deliveries) was over 100% higher in a Twenty20 game compared to training. Psychomotor speed was unchanged although error within the cognitive task increased post Twenty20 (391±82±547±104 ms) and training (414±110±561±238 ms). This data suggests that reaction time is unchanged from cricket but the chance of making the incorrect decision is increased. CONCLUSIONS Movements in fielding should be quantified or bowling workloads adjusted to account for the high intensity fielding associated with Twenty20 cricket. Cognitive function was impaired following bowling, suggesting practitioners may also monitor psychomotor changes when assessing fatigue and allow appropriate time to mentally recover.

Deep ocean mineral supplementation enhances the cerebral hemodynamic response during exercise and decreases inflammation postexercise in men at two age levels.

Background: Previous studies have consistently shown that oral supplementation of deep ocean minerals (DOM) improves vascular function in animals and enhances muscle power output in exercising humans. Purpose: To examine the effects of DOM supplementation on the cerebral hemodynamic response during physical exertion in young and middle-aged men. Design: Double-blind placebo-controlled crossover studies were conducted in young (N = 12, aged 21.2 ± 0.4 years) and middle-aged men (N = 9, aged 46.8 ± 1.4 years). The counter-balanced trials of DOM and Placebo were separated by a 2-week washout period. DOM and Placebo were orally supplemented in drinks before, during, and after cycling exercise. DOM comprises desalinated minerals and trace elements from seawater collected ~618 m below the earths surface. Methods: Cerebral hemodynamic response (tissue hemoglobin) was measured during cycling at 75% VO2max using near infrared spectroscopy (NIRS). Results: Cycling time to exhaustion at 75% VO2max and the associated plasma lactate response were similar between the Placebo and DOM trials for both age groups. In contrast, DOM significantly elevated cerebral hemoglobin levels in young men and, to a greater extent, in middle-aged men compared with Placebo. An increased neutrophil to lymphocyte ratio (NLR) was observed in middle-aged men, 2 h after exhaustive cycling, but was attenuated by DOM. Conclusion: Our data suggest that minerals and trace elements from deep oceans possess great promise in developing supplements to increase the cerebral hemodynamic response against a physical challenge and during post-exercise recovery for middle-aged men.