102,126 research outputs found
Influence of a montmorency cherry juice blend on indices of exercise-induced stress and upper respiratory tract symptoms following marathon running - a pilot investigation
No full textThis is the first study that provides encouraging evidence of the potential role of Montmorency cherries in reducing the development of URTS post-Marathon possibly caused by exercise-induced hyperventilation trauma, and/or other infectious and non-infectious factors
The plasma bioavailability of nitrate and betanin from Beta vulgaris rubra in humans
No full textPurpose
To evaluate the plasma bioavailability of betanin and nitric oxide (NOx) after consuming beetroot juice (BTJ) and whole beetroot (BF). BTJ and BF were also analysed for antioxidant capacity, polyphenol content (TPC) and betalain content.
Methods
Ten healthy males consumed either 250 ml of BTJ, 300 g of BF or a placebo drink, in a randomised, crossover design. Venous plasma samples were collected pre (baseline), 1, 2, 3, 5 and 8 h post-ingestion. Betanin content in BTJ, BF and plasma was analysed with reverse-phase high-performance liquid chromatography (HPLC) and mass spectrometry detection (LCMS). Antioxidant capacity was estimated using the Trolox equivalent antioxidant capacity (TEAC) and polyphenol content using Folin–Ciocalteu colorimetric methods [gallic acid equivalents (GAE)] and betalain content spectrophotometrically.
Results
TEAC was 11.4 ± 0.2 mmol/L for BTJ and 3.4 ± 0.4 μmol/g for BF. Both BTJ and BF contained a number of polyphenols (1606.9 ± 151 mg/GAE/L and 1.67 ± 0.1 mg/GAE/g, respectively), betacyanins (68.2 ± 0.4 mg/betanin equivalents/L and 19.6 ± 0.6 mg/betanin equivalents/100 g, respectively) and betaxanthins (41.7 ± 0.7 mg/indicaxanthin equivalents/L and 7.5 ± 0.2 mg/indicaxanthin equivalents/100 g, respectively). Despite high betanin contents in both BTJ (~194 mg) and BF (~66 mg), betanin could not be detected in the plasma at any time point post-ingestion. Plasma NOx was elevated above baseline for 8 h after consuming BTJ and 5 h after BF (P < 0.05).
Conclusions
These data reveal that BTJ and BF are rich in phytonutrients and may provide a useful means of increasing plasma NOx bioavailability. However, betanin, the major betalain in beetroot, showed poor bioavailability in plasma
Neuromuscular response differences to power vs strength back squat exercise in elite athletes
No full textThe study’s aim was to establish the neuromuscular responses in elite athletes during and following maximal ‘explosive’ regular back squat exercise at heavy, moderate and light loads. Ten elite track and field athletes completed 10 sets of 5 maximal squat repetitions on three separate days. Knee extension maximal voluntary isometric contraction (MVIC), rate of force development (RFD) and evoked peak twitch force (Pt) assessments were made pre- and post-session. Surface electromyography amplitude (RMS) and mechanical measurements were made continuously during all repetitions. The heavy session resulted in the greatest repetition impulse in comparison to moderate and light sessions (p<0.001), whilst the latter showed highest repetition power (p<0.001). MIVC, RFD and Pt force values were significantly reduced post-session (p<0.01), with greatest reduction observed after the heavy, followed by the moderate and light sessions accordingly. Repetition power significantly reduced during sets of the heavy session only (p<0.001), and greater increases in repetition RMS occurred during heavy session (p<0.001), followed by moderate, with no change during light session. In conclusion, this study has shown in elite athletes that the moderate load is optimal for providing a neuromuscular stimulus but with limited fatigue. This type of intervention could be potentially used in the development of both strength and power in elite athletic populations
The Potential Benefits of Red Beetroot Supplementation in Health and Disease
No full textIn recent years there has been a growing interest in the biological activity of red beetroot (Beta vulgaris rubra) and its potential utility as a health promoting and disease preventing functional food. As a source of nitrate, beetroot ingestion provides a natural means of increasing in vivo nitric oxide (NO) availability and has emerged as a potential strategy to prevent and manage pathologies associated with diminished NO bioavailability, notably hypertension and endothelial function. Beetroot is also being considered as a promising therapeutic treatment in a range of clinical pathologies associated with oxidative stress and inflammation. Its constituents, most notably the betalain pigments, display potent antioxidant, anti-inflammatory and chemo-preventive activity in vitro and in vivo. The purpose of this review is to discuss beetroot’s biological activity and to evaluate evidence from studies that specifically investigated the effect of beetroot supplementation on inflammation, oxidative stress, cognition and endothelial function
Mirror training to augment cross-education during resistance training: a hypothesis
No full textResistance exercise has been shown to be a potent stimulus for neuromuscular adaptations. These adaptations are not confined to the exercising muscle and have been consistently shown to produce increases in strength and neural activity in the contralateral, homologous resting muscle; a phenomenon known as cross-education. This observation has important clinical applications for those with unilateral dysfunction given that cross-education increases strength and attenuates atrophy in immobilized limbs. Previous evidence has shown that these improvements in the transfer of strength are likely to reside in areas of the brain, some of which are common to the mirror neuron system (MNS). Here we examine the evidence for the, as yet, untested hypothesis that cross-education might benefit from observing our own motor action in a mirror during unimanual resistance training, thereby activating the MNS. The hypothesis is based on neuroanatomical evidence suggesting brain areas relating to the MNS are activated when a unilateral motor task is performed with a mirror. This theory is timely because of the growing body of evidence relating to the efficacy of cross-education. Hence, we consider the clinical applications of mirror training as an adjuvant intervention to cross-education in order to engage the MNS, which could further improve strength and reduce atrophy in dysfunctional limbs during rehabilitation
Analgesic and anti-inflammatory drugs in sports: implications for exercise performance and training adaptations
No full textOver-the-counter analgesics, such as anti-inflammatory drugs (NSAIDs) and paracetamol, are widely consumed by athletes worldwide to increase pain tolerance, or dampen pain and reduce inflammation from injuries. Given that these drugs also can modulate tissue protein turnover, it is important to scrutinize the implications of acute and chronic use of these drugs in relation to exercise performance and the development of long-term training adaptations. In this review we aim to provide an overview of the studies investigating the effects of analgesic drugs on exercise performance and training adaptations relevant for athletic development. There is emerging evidence that paracetamol might acutely improve important endurance parameters as well as aspects of neuromuscular performance, possibly through increased pain tolerance. Both NSAIDs and paracetamol have been demonstrated to inhibit cyclooxygenase (COX) activity, which might explain the reduced anabolic response to acute exercise bouts. Consistent with this, NSAIDs have been reported to interfere with muscle hypertrophy and strength gains in response to chronic resistance training in young individuals. Although it remains to be established whether any of these observations also translate into detriments in sport-specific performance or reduced training adaptations in elite athletes, the extensive use of these drugs certainly raises practical, ethical and important safety concerns that need to be adressed. Overall, we encourage greater awareness among athletes, coaches and support staff on the potential adverse effects of these drugs. A risk-benefit analysis and professional guidance is strongly advised before the athlete considers analgesic medicine for training or competition
Prediction of flatwater kayaking performance
No full textPurpose: To determine the relative importance of anthropometric and physiological attributes for performance in the 1000-m, 500-m, and 200-m flatwater kayaking events. Methods: Eighteen competitive male kayakers completed performance trials over the 3 distances and a battery of anthropometric and physiological tests. Results: Performance times (mean ± SD) for 1000 m, 500 m, and 200 m were 262.56 ± 36.44 s, 122.10 ± 5.74 s, and 41.59 ± 2.12 s, respectively. Performance in all 3 events was correlated with a number of physiological parameters; in addition, 500-m and 200-m performance was correlated with upper body dimensions. 1000-m time was predicted by power output at lactate turnpoint expressed as a percentage of maximal aerobic power, work done in a 30-s ergometry test and work done in a 2-min ergometry test (adjusted R2 = 0.71, SEE = 5.72 s); 500-m time was predicted by work done and the fatigue index in a 30-s ergometry test, work done in a 2-min ergometry test, peak isometric and isokinetic function (adjusted R2 = 0.79, SEE = 2.49 s); 200-m time was predicted by chest circumference, humeral breadth, peak power, work done, and the fatigue index in a 30-s ergometry test (adjusted R2 = 0.71, SEE = 0.71 s). Conclusions: A number of physiological variables are correlated with performance in all events. 1000-m, 500-m, and 200-m times were predicted with a standard error of only 2.2%, 2.0%, and 1.7%, respectively
Transcranial magnetic stimulation in sport science: a commentary
No full textThe aim of this commentary is to provide a brief overview of transcranial magnetic stimulation (TMS) and highlight how this technique can be used to investigate the acute and chronic responses of the central nervous system to exercise.
We characterise the neuromuscular responses to TMS and discuss how these measures can be used to investigate the mechanisms of fatigue in response to locomotor exercise. We also discuss how TMS might be used to study the corticospinal adaptations to resistance exercise training, with particular emphasis on the responses to shortening/lengthening contractions and contralateral training. The limited data to date suggest that TMS is a valuable technique for exploring the mechanisms of central fatigue and neural adaptation
Critical Difference and Biological Variation in Biomarkers of Oxidative Stress and Nutritional Status in Athletes
No full textThe longitudinal monitoring of oxidative stress (OS) in athletes may enable the identification of fatigued states and underperformance. The application of OS biomarker monitoring programs in sport are hindered by reliability and repeatability of in-the-field testing tools, the turnaround of results, and the understanding of biological variation (BV). Knowledge of BV and critical difference values (CDV) may assist with data interpretation in the individual athlete. Methods: We aimed firstly to assess the repeatability of the clinical point of care redox test, Free Oxygen Radical Test (FORT) and the Free Oxygen Radical Defence (FORD) in trained participants and elite athletes and secondly to calculate the analytical, BV, CDV and index of individuality (II) for FORT, FORD, red blood cell glutathione, lutein, α and γ–tocopherol. Part 1: Fifteen elite athletes were sampled in duplicate for calculation of the repeatability of the FORT and FORD tests. Part 2: Twelve well-trained athletes had venous samples drawn every 2 hours from 0800 to 1800 for calculation of BV, CDV, II for FORT, FORD, RBC GSH, lutein, α-tocopherol and γ–tocopherol. Results: Repeatability of the FORT and FORD assay was 3.9% and 3.7% respectively. Biomarker CDV ranged from 12.8% to 37%, with a circadian effect for FORT, α-tocopherol and γ-tocopherol (p<0.01), with all biomarker indices of individuality < 0.8 arbitrary units. Conclusion: We report that the use of the novel redox test in athletes is practical, and the generation of BV and CDV for biomarkers of OS enhances the interpretation of physiologically meaningful changes in individuals above the use of clinical reference ranges alone
The role of cherries in exercise and health
No full textRecently, cherries and cherry products have received growing attention within the literature with regards to their application in both exercise and clinical paradigms. Reported to be high in anti-inflammatory and anti-oxidative capacity, cherries and their constituents are proposed to provide a similar, but natural alternative akin to over-the-counter non-steroidal anti-inflammatory drugs (NSAID’s) or analgesics. Within exercise paradigms, concern has been raised with regards to the use of products which inhibit such inflammatory or oxidative actions, due to the possibility of the blunting of physiological training adaptations. Despite this, numerous scenarios exist both within exercise and clinical populations where a goal of optimal recovery time is more important than physiological adaptation. This review critically evaluates and discusses the use of cherries as a supplementation strategy to enhance recovery of muscle function, inhibit exercise-induced inflammation, oxidative stress and pain primarily; furthermore the potential application of cherries to clinical populations is discussed
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