• Biochemistry of buffering capacity and ingestion of buffers in exercise and athletic performance

      Saunders, Bryan; Artioli, Guilherme Giannini; Dolan, Eimear; Jones, Rebecca Louise; Matthews, Joseph; Sale, Craig (Routledge International Handbooks, 2021-01-22)
    • Carnosine in health and disease

      Artioli, Guilherme Giannini; Sale, Craig; Jones, Rebecca Louise; Nottingham Trent University; University of Bedfordshire (Taylor and Francis, 2018-03-04)
      Carnosine was originally discovered in skeletal muscle, where it exists in larger amounts than in other tissues. The majority of research into the physiological roles of carnosine have been conducted on skeletal muscle. Given this and the potential for muscle carnosine content to be increased with supplementation, there is now a large body of research examining the ergogenic effects (or otherwise) of carnosine. More recent research, however, points towards a potential for carnosine to exert a wider range of physiological effects in other tissues, including the brain, heart, pancreas, kidney and cancer cells. Taken together, this is suggestive of a potential for carnosine to have therapeutic benefits in health and disease, although this is by no means without complication. Herein, we will provide a review of the current literature relating to the potential therapeutic effects of carnosine in health and disease.
    • Carnosine: from exercise performance to health

      Jones, Rebecca Louise (2017-09-20)
    • The dose-response to sodium bicarbonate ingestion highlights the need for individuality in supplementation

      Jones, Rebecca Louise; Stellingwerff, Trent; Artioli, Guilherme Giannini; Saunders, Bryan; Cooper, Simon; Sale, Craig; Nottingham Trent University; Canadian Sport Institute; University of São Paulo (Human Kinetics Journal, 2016-10-01)
      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.
    • The effect of expertise on coordination variability during a discrete multi-articular action

      Jones, Rebecca Louise; Robins, M. (2017-09-20)
      Introduction When investigating the relationship between task expertise and movement variability, contrasting findings have been reported in scientific literature (e.g. Darling and Cooke, 1987; Wilson, et al., 2008; Robins, et al., 2008). These equivocal reports could be due, to task constraints influencing variability magnitudes. Whilst some research has used static accuracy-based tasks (Darling and Cooke, 1987), more complex, dynamic multi-articular movements tasks have also been used (Wilson, et al., 2008; Robins, et al., 2008). Currently there is a lack of research examining task expertise-movement variability during such dynamic movement tasks, and ultimately how movement variability can be used functionally to satisfy the specific constraints on action. Therefore, the purpose of this study was to examine the interaction of expertise and coordination variability during a dynamic basketball shooting task. Methods Male university basketball players (n=8) with varying basketball experience (scoring between 35-80% of pre-test shots) performed 20 shots from a distance of 4.25 metres after a dribbling movement of 6.5 metres. Kinematic data was collected from a seven-camera motion capture system sampling at 200Hz. 14mm reflective markers attached to upper limb anatomical landmarks allowed calculation of shoulder, elbow and wrist angular displacements. Coordination variability for the wrist-elbow, elbow-shoulder, and wrist-shoulder joint couplings were produced using the normalised root mean squared difference (NoRMS) approach. Providing a metric by which the degree of consistency may be assessed, as such, one measure of stability of the underlying coordination. Quadratic regression analysis was used to identify the potential relationship between joint coupling coordination variability and shooting score. Results The quadratic regression values for the wrist-elbow joint coupling was 0.1609 (p=0.48), elbow-shoulder, 0.1109 (p=0.66), and wrist-shoulder, 0.6467 (p=0.02) with respect to shooting performance score. Discussion Similar to previous research, task performance and coordination variability demonstrated an U-shaped relationship (Wilson, et al., 2008). Intermediate skilled participants displayed the lowest coordination variability; whilst higher skilled participants demonstrated higher functional variability owing to adapting to perturbations (Hamill, 1999). Least skilled participants revealed variability that is less functional and evident of less stable movement patterns. Additional research is needed, to further understand the task expertise-movement variability relationship for different task constraints
    • The prevalence of daily sedentary time in south Asian adults: a systematic review

      Dey, Kamalesh C.; Zakrzewski-Fruer, Julia K.; Smith, Lindsey Rachel; Jones, Rebecca Louise; Bailey, Daniel Paul (MDPI, 2021-09-01)
      This study aimed to systematically review total daily sedentary time in South Asian adults. Seven electronic databases were searched, identifying relevant articles published in peer-reviewed journals between March 1990 and March 2021. The study was designed in accordance with PRISMA guidelines. Prospective or cross-sectional design studies reporting total daily sedentary time in South Asian adults (aged ≥18 years), reported in English, were included. Study quality and risk of bias were assessed, and the weighted mean total daily sedentary time was calculated. Fourteen full texts were included in this systematic review from studies that were conducted in Bangladesh, India, Norway, Singapore, and the United Kingdom. Pooled sedentary time across all studies was 424 ± 8 min/day. Sedentary time was measured using self-report questionnaires in seven studies, with a weighted mean daily sedentary time of 416 ± 19 min/day. Eight studies used accelerometers and inclinometers with a weighted mean sedentary time of 527 ± 11 min/day. South Asian adults spend a large proportion of their time being sedentary, especially when recorded using objective measures (~9 h/day). These findings suggest that South Asians are an important target population for public health efforts to reduced sedentary time, and researchers and practitioners should seek to standardise and carefully consider the tools used when measuring sedentary time in this population.
    • Sodium bicarbonate ingestion improves cycling performance, irrespective of single or split dose ingestion

      Jones, Rebecca Louise; Stellingwerff, Trent; Swinton, P.; Artioli, Guilherme Giannini; Sale, Craig (2016-12-21)
    • Warm-up intensity does not affect the ergogenic effect of sodium bicarbonate in adult men

      Jones, Rebecca Louise; Stellingwerff, Trent; Artioli, Guilherme Giannini; Saunders, Bryan; Sale, Craig; Swinton, Paul; ; University of Bedfordshire; Canadian Sport Institute–Pacific; University of Victoria; et al. (Human Kinetics, 2021-09-03)
      This study determined the influence of a high (HI) vs. low-intensity (LI) cycling warm-up on blood acid-base responses and exercise capacity following ingestion of sodium bicarbonate (SB; 0.3 g·kg-1 body-mass (BM)) or a placebo (PLA; maltodextrin) 3-hours prior to warm-up. Twelve men (21±2 years, 79.2±3.6 kg BM, maximum power output (Wmax) 318±36 W) completed a familiarisation and four double-blind trials completed in a counterbalanced order: HI warm-up with SB (HISB); HI warm-up with PLA (HIPLA); LI warm-up with SB (LISB); and LI warm-up with PLA (LIPLA). LI warm-up was 15-minutes at 60%Wmax, while the HI warm-up (typical of elites) featured LI followed by 2 x 30-sec (3-minute break) at Wmax, finishing 30-minute prior to a cycling capacity test at 110%Wmax (CCT110%). Blood bicarbonate and lactate were measured throughout. SB supplementation increased blood bicarbonate (+6.4 [95%CI: 5.7 to 7.1 mmol·L-1]) prior to greater reductions with high intensity warm-up (-3.8 [95%CI: -5.8 to -1.8 mmol·L-1]). However, during the 30-minute recovery, blood bicarbonate rebounded and increased in all conditions, with concentrations ~5.3mmol·L-1 greater with SB supplementation (P<0.001). Blood bicarbonate significantly declined during the CCT110% with greater reductions following SB supplementation (-2.4 [95%CI: -3.8 to -0.90 mmol·L-1]). Aligned with these results, SB supplementation increased total work done during the CCT110% (+8.5 [95%CI: 3.6 to 13.4 kJ], ~19% increase) with no significant main effect of warm-up intensity (+0.0 [95%CI: -5.0 to 5.0 kJ). Collectively, the results demonstrate that SB supplementation can improve HI cycling capacity irrespective of prior warm-up intensity, likely due to blood alkalosis.
    • Warm-up intensity does not influence the beneficial effect of sodium bicarbonate ingestion on cycling performance

      Jones, Rebecca Louise; Stellingwerff, Trent; Swinton, P.; Artioli, Guilherme Giannini; Sale, Craig (2016-12-21)
    • β-alanine supplementation enhances human skeletal muscle relaxation speed but not force production capacity

      Hannah, Ricci; Jones, Rebecca Louise; Minshull, Claire; Artioli, Guilherme Giannini; Harris, Roger C.; Sale, Craig (American Physiological Society, 2015-03-01)
      PURPOSE: β-alanine (BA) supplementation improves human exercise performance. One possible explanation for this is an enhancement of muscle contractile properties, occurring via elevated intramuscular carnosine resulting in improved calcium sensitivity and handling. This study investigated the effect of BA supplementation on in vivo contractile properties and voluntary neuromuscular performance. METHODS: Twenty-three men completed two experimental sessions, pre- and post-28 days supplementation with 6.4 g·d-1 39 of BA (n = 12) or placebo (PLA; n = 11). During each session, force was recorded during a series of knee extensor contractions: resting and potentiated twitches and octet (8 pulses, 300 Hz) contractions elicited via femoral nerve stimulation; tetanic contractions (1 s, 1 – 100 Hz) via superficial muscle stimulation; and maximum and explosive voluntary contractions. RESULTS: BA supplementation had no effect on the force-frequency relationship, or the force responses (force at 25 ms and 50 ms from onset, peak force) of resting or potentiated twitches, and octet contractions (P > 0.05). Resting and potentiated twitch electromechanical delay and time-to-peak tension were unaffected by BA supplementation (P > 0.05), although half-relaxation time declined by 7-12% (P < 0.05). Maximum and explosive voluntary forces were unchanged after BA supplementation. CONCLUSION: BA supplementation had no effect on evoked force responses, implying that altered calcium sensitivity and/or release are not the mechanisms by which BA supplementation influences exercise performance. The reduced half-relaxation time with BA supplementation might, however, be explained by enhanced reuptake of calcium, which has implications for the efficiency of muscle contraction following BA supplementation.
    • β-alanine supplementation enhances human skeletal muscle relaxation speed but not force production capacity

      Jones, Rebecca Louise; Hannah, Ricci; Minshull, Claire; Artioli, Guilherme Giannini; Harris, Roger C.; Sale, Craig (2015-09-20)
    • β-alanine supplementation improves in-vivo fresh and fatigued muscle relaxation speed

      Jones, Rebecca Louise; Barnett, T.C.; Davidson, Joel; Maritza, Billy; Fraser, William D.; Harris, Roger C.; Sale, Craig (2017-09-20)
    • β-alanine supplementation improves in-vivo fresh and fatigued muscle relaxation speed

      Jones, Rebecca Louise; Barnett, Cleveland Thomas; Davidson, Joel; Maritza, Billy; Fraser, William D.; Harris, Roger C.; Sale, Craig; Nottingham Trent University; University of East Anglia; Norfolk and Norwich University Hospital; et al. (Springer International Publishing AG, 2017-03-27)
      PURPOSE: In fresh muscle, supplementation with the rate-limiting precursor of carnosine, β-alanine (BA), results in a decline in muscle half-relaxation time (HRT) potentially via alterations to calcium (Ca2+) handling. Accumulation of hydrogen cation (H+) has been shown to impact Ca2+ signalling during muscular contraction, carnosine has the potential to serve as a cytoplasmic regulator of Ca2+ and H+ coupling, since it binds to both ions. The present study examined the effect of BA supplementation on intrinsic in-vivo isometric knee extensor force production and muscle contractility in both fresh and fatigued human skeletal muscle assessed during voluntary and electrically evoked (nerve and superficial muscle stimulation) contractions. METHODS: Twenty-three males completed two experimental sessions, pre- and post- 28 day supplementation with 6.4 g.day-1 of BA (n = 12) or placebo (PLA; n = 11). Isometric force was recorded during a series of voluntary and electrically evoked knee extensor contractions. RESULTS: BA supplementation had no effect on voluntary or electrically evoked isometric force production, or twitch electromechanical delay and time-to-peak tension. There was a significant decline in muscle HRT in fresh and fatigued muscle conditions during both resting (3 ± 13%; 19 ± 26%) and potentiated (1 ± 15%; 2 ± 20%) twitch contractions. CONCLUSIONS: The mechanism for reduced HRT in fresh and fatigued skeletal muscle following BA supplementation is unclear. Due to the importance of muscle relaxation on total energy consumption, especially during short, repeated contractions, BA supplementation may prove to be beneficial in minimising contractile slowing induced by fatigue. TRIAL REGISTRATION: The trial is registered with Clinicaltrials.gov, ID number NCT02819505.