Chris Easton

A Single Dose of Beetroot Juice Enhances Cycling Performance in Simulated Altitude

INTRODUCTION Increasing nitric oxide bioavailability via supplementation with nitrate-rich beetroot juice (BR) has been shown to attenuate the negative effect of hypoxia on peripheral oxygen saturation and exercise tolerance. PURPOSE We investigated the effects of a single dose of concentrated BR on the physiological responses to submaximal exercise and time trial (TT) performance in trained cyclists exposed to moderate simulated altitude (approximately 2500 m). METHODS Nine competitive amateur male cyclists (age, 28 ± 8 yr; V˙O2peak at altitude, 51.9 ± 5.8 mL·kg·min) completed four exercise trials consisting of an initial graded test to exhaustion and three performance trials on a cycle ergometer. The performance trials comprised 15 min of submaximal steady-state exercise at 60% maximum work rate and a 16.1-km TT. The second and third trials were preceded by ingestion of either 70 mL of BR or nitrate-depleted BR (PLA) 3 h before exercise. RESULTS Plasma nitrate (PLA, 39.1 ± 3.5 µM; BR, 150.5 ± 9.3 µM) and nitrite (PLA, 289.8 ± 27.9 nM; BR, 678.1 ± 103.5 nM) measured immediately before exercise were higher after ingestion of BR compared with that after PLA (P < 0.001, P = 0.004). V˙O2 during steady-state exercise was lower in the BR trial (2542 ± 114 mL·min) than that in the PLA trial (2727 ± 85 mL·min, P = 0.049). TT performance was significantly faster after BR (1664 ± 14 s) than that after PLA (1702 ± 15 s, P = 0.021). CONCLUSION A single dose of BR lowered V˙O2 during submaximal exercise and enhanced TT performance of trained cyclists in normobaric hypoxia. Consequently, ingestion of BR may be a practical and effective ergogenic aid for endurance exercise at altitude.

Impact of methodological decisions on accelerometer outcome variables in young children

Background:The impact of accelerometer-related methodological decisions relating to the assessment of physical activity and sedentary time has not been conclusively determined in young children.Objectives:To determine the effects of epoch and cutoff points on the assessment of physical activity and sedentary time and to determine the accelerometer wear time required to achieve reliable accelerometer data in children.Design:Children were recruited from centres at Ghent, Glasgow, Gothenburg and Zaragoza.Methods:Physical activity was assessed for 1 week in 86 children (41 girls, 45 boys; mean age 7±2 years) by uniaxial accelerometry. The epoch was set at 15 s and reintegrated to 30 and 60 s. Time spent sedentary and in moderate and vigorous physical activity (MVPA) was assessed using a range of cutoff points. Number of days required to achieve 80% reliability was predicted using the Spearman–Brown Prophecy formula.Results:The Reilly cutoff points (<1100 counts per min (CPM)) indicated less sedentary time per day when comparing 15 vs 30 s and 15 vs 60 s epochs: 570±91 vs 579±93 min and 570±91 vs 579±94 min, respectively; P<0.05. Pate cutoff points (>420 counts per 15 s) reported more MVPA time per day compared with Sirard (890 counts per 15 s) and Puyau cutoff points (>3200 counts per min) using 15 s epoch: 78 (4–197) min (median (range) vs 18 (1–80) min and 24 (1–100) min, respectively; P<0.001. Compliance with guidelines of at least 60 min MVPA was 84, 78 and 73% for Pate cutoff points using 15, 30 and 60 s epochs, respectively, but 0% for Sirard and Puyau cutoff points across epochs. The number of days required to achieve 80% reliability for CPM, sedentary and MVPA time was 7.4–8.5 days.Conclusion:Choice of epoch and cutoff point significantly influenced the classification of sedentary and MVPA time and observed compliance to the MVPA guidelines.

Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists

Dietary nitrate supplementation has been shown to increase nitric oxide (NO) metabolites, reduce blood pressure (BP) and enhance exercise performance. Acute exposure to ultraviolet (UV)-A light also increases NO bioavailability and reduces BP. We conducted a randomized, counterbalanced placebo-controlled trial to determine the effects of UV-A light alone and in combination with nitrate on the responses to sub-maximal steady-state exercise and time trial (TT) performance. Nine cyclists (VO2max 53.1 ± 4.4 ml/kg/min) completed five performance trials comprising 10 min submaximal steady-state cycling followed by a 16.1 km TT. Following a familiarization the final four trials were preceded, in random order, by either (1) Nitrate gels (NIT) + UV-A, (2) Placebo (PLA) + UV-A, (3) NIT + Sham light (SHAM) and (4) PLA + SHAM (control). The NIT gels (2 × 60 ml gels, ~8.1 mmol nitrate) or a low-nitrate PLA were ingested 2.5 h prior to the trial. The light exposure consisted of 20 J/cm(2) whole body irradiation with either UV-A or SHAM light. Plasma nitrite was measured pre- and post-irradiation and VO2 was measured continuously during steady-state exercise. Plasma nitrite was higher for NIT + SHAM (geometric mean (95% CI), 332 (292-377) nM; P = 0.029) and NIT + UV-A (456 (312-666) nM; P = 0.014) compared to PLA + SHAM (215 (167-277) nM). Differences between PLA + SHAM and PLA + UV-A (282 (248-356) nM) were small and non-significant. During steady-state exercise VO2 was reduced following NIT + UVA (P = 0.034) and tended to be lower in NIT + SHAM (P = 0.086) but not PLA + UV-A (P = 0.381) compared to PLA + SHAM. Performance in the TT was significantly faster following NIT + UV-A (mean ± SD 1447 ± 41 s P = 0.005; d = 0.47), but not PLA + UV-A (1450 ± 40 s; d = 0.41) or NIT + SHAM (1455 ± 47 s; d = 0.28) compared to PLA + SHAM (1469 ± 52 s). These findings demonstrate that exposure to UV-A light alone does not alter the physiological responses to exercise or improve performance in a laboratory setting. A combination of UV-A and NIT, however, does improve cycling TT performance in this environment, which may be due to a larger increase in NO availability.

The Application of Metabolomic Profiling to the Effects of Physical Activity

Physical activity and exercise are potent lifestyle interventions for the reduction of several psychosomatic risks, including cardiovascular disease, diabetes and mild-to-moderate depression. The current review describes the studies which have utilised a metabolomics/ metabolite profiling approach in combination with exercise in the period between 1999-2014 in predominantly healthy subjects (N:64) and in a smaller subset of patient cohorts (N:10) between 2011-2014. A broad range of intervention types were used in both healthy and patient cohorts with varying exercise regimes with or without supplement use. Effects on purine metabolism, which have been known for over 40 years, were by far the most well-cited and persistent finding. Other reported effects included observations of: glucocorticoid and androgen metabolism, glycolysis and Krebs cycle, gluconeogenesis, fatty acid metabolism, fatty acid oxidation and pantothenic acid, amino acid oxidation, tryptophan metabolism and effects on microbiome metabolites. The discussion section draws observations from the very disparate studies together and links them to the general aspects of human metabolism.

The effects of dietary nitrate supplementation on the adaptations to sprint interval training in previously untrained males

OBJECTIVES Dietary nitrate can improve repeated high-intensity and supramaximal exercise performance, although the effect on adaptations to training has received limited attention. The purpose of this study was to investigate the effects of dietary nitrate on the response to 3-weeks of sprint interval training (SIT). DESIGN Randomized control trial. METHODS Twenty-seven untrained males (Age: 28±7 y, V⋅O2Max: 42±7mlkg-1min-1) completed an incremental exercise test at the beginning and end of the study. Participants were matched for V⋅O2Max and randomly assigned to a control group (CON; n=8), SIT+placebo group (PLA; n=10), or SIT+nitrate group (NIT; n=9). The SIT comprised 4-6 repeated 15 s all out sprints on a cycle ergometer, interspersed with 4min active recovery, 3-times per week. Approximately 2.5h prior to exercise, participants consumed gels containing ∼0.1mmol (PLA) or ∼8mmol nitrate (NIT). RESULTS Following SIT, V⋅O2Max (PLA: 5%, p=0.057, d=0.34; NIT: 6.3%, p=0.041, d=0.34) and ventilatory threshold (VT) increased to a similar extent in both SIT groups. Maximum work rate tended to increase to a greater extent in NIT (8.7%, d=0.55) compared to PLA (4.7%, d=0.31, p=0.073). Fatigue index, calculated by the change in mean power from the first to the last sprint, tended to be reduced following SIT in NIT compared to PLA (PLA: 7.3±7.4%, NIT: 0.5±7.1%, p=0.058). CONCLUSIONS While dietary nitrate supplementation does not augment improvements to V⋅O2Max and VT following SIT, it may improve WRmax and indices of repeated high-intensity exercise.

Combined triaxial accelerometry and heart rate telemetry for the physiological characterization of Latin dance in non-professional adults.

The purpose of this study was to value calibrate, cross-validate, and determine the reliability of a combined triaxial accelerometry and heart rate telemetry technique for characterizing the physiological and physical activity parameters of Latin dance. Twenty-two non-professional adult Latin dancers attended two laboratory-based dance trials each. After familiarization and a standardized warm-up, a multi-stage (3 x 5-minute) incremental (based on song tempo) Afro-Cuban salsa choreography was performed while following a video displayed on a projection screen. Data were collected with a portable indirect calorimeter, a heart rate telemeter, and wrist-, hip-, and ankle-mounted ActiGraph GT3X+ accelerometers. Prediction equations for energy expenditure and step count were value calibrated using forced entry multiple regression and cross-validated using a delete-one jackknife approach with additional Bland-Altman analysis. The average dance intensity reached 6.09 ± 0.96 kcal/kg/h and demanded 45.9 ± 11.3% of the heart rate reserve. Predictive ability of the derived models was satisfactory, where R(2) = 0.80; SEE = 0.44 kcal/kg/h and R(2) = 0.74; SEE = 3 step/min for energy expenditure and step count, respectively. Dependent t-tests indicated no differences between predicted and measured values for both energy expenditure (t65 = -0.25, p = 0.80) and step count (t65 = -0.89, p = 0.38). The 95% limits of agreement for energy expenditure and step count were -0.98 to 0.95 kcal/kg/h and -7 to 7 step/min, respectively. Latin dance to salsa music elicits physiological responses representative of moderate to vigorous physical activity, and a wrist-worn accelerometer with simultaneous heart rate measurement constitutes a valid and reliable technique for the prediction of energy expenditure and step count during Latin dance.

Stability of the K4b 2 portable metabolic analyser during rest, walking and running

Abstract This study investigated the stability of the measurement of respiratory variables during rest, walking and running using the K4b2 portable metabolic analyser in ten active males (age 31 ± 11 years; peak 42.1 ± 2.6 ml · min−1 · kg−1). Following a 10 min rest, participants completed three discontinuous incremental exercise tests on a treadmill while walking (4, 5 and 6 km · h−1) and running (8, 10, 12, 14 and 16 km · h−1, or until volitional exhaustion). Participants completed 3 min of exercise at each speed, followed by a 3 min recovery after each stage above 10 km · h−1. The respiratory variables were measured using either a laboratory-based metabolic cart as a reference method (Oxycon Pro, OP), a K4b2 calibrated immediately before the test (K4b2), or a K4b2 calibrated 1 h before the test (K4b2DEL). Compared to the OP, carbon dioxide production () and were not different when measured by K4b2 or K4b2DEL. There was no difference in between OP and K4b2 tests (P = 0.19, mean difference = 38 ml · min−1 and limits of agreement (LOA) = 208 to –285) although K4b2DEL overestimated (P = 0.05, mean difference = 84 ml · min−1 and LOA = 302 to –469). These data suggest that a drift in measurement accuracy appears to cause the K4b2 to overestimate in tests lasting longer than 1 h.

Validation of anthropometry and foot-to-foot bioelectrical resistance against a three-component model to assess total body fat in children: the IDEFICS study

Objective:To compare different field methods for estimating body fat mass with a reference value derived by a three-component (3C) model in pre-school and school children across Europe.Design:Multicentre validation study.Subjects:Seventy-eight preschool/school children aged 4–10 years from four different European countries.Methods:A standard measurement protocol was carried out in all children by trained field workers. A 3C model was used as the reference method. The field methods included height and weight measurement, circumferences measured at four sites, skinfold measured at two–six sites and foot-to-foot bioelectrical resistance (BIA) via TANITA scales.Results:With the exception of height and neck circumference, all single measurements were able to explain at least 74% of the fat-mass variance in the sample. In combination, circumference models were superior to skinfold models and height–weight models. The best predictions were given by trunk models (combining skinfold and circumference measurements) that explained 91% of the observed fat-mass variance. The optimal data-driven model for our sample includes hip circumference, triceps skinfold and total body mass minus resistance index, and explains 94% of the fat-mass variance with 2.44 kg fat mass limits of agreement. In all investigated models, prediction errors were associated with fat mass, although to a lesser degree in the investigated skinfold models, arm models and the data-driven models.Conclusion:When studying total body fat in childhood populations, anthropometric measurements will give biased estimations as compared to gold standard measurements. Nevertheless, our study shows that when combining circumference and skinfold measurements, estimations of fat mass can be obtained with a limit of agreement of 1.91 kg in normal weight children and of 2.94 kg in overweight or obese children.

Effects of Glycerol and Creatine Hyperhydration on Doping-Relevant Blood Parameters

Glycerol is prohibited as an ergogenic aid by the World Anti-Doping Agency (WADA) due to the potential for its plasma expansion properties to have masking effects. However, the scientific basis of the inclusion of Gly as a “masking agent” remains inconclusive. The purpose of this study was to determine the effects of a hyperhydrating supplement containing Gly on doping-relevant blood parameters. Nine trained males ingested a hyperhydrating mixture twice per day for 7 days containing 1.0 g·kg−1 body mass (BM) of Gly, 10.0 g of creatine and 75.0 g of glucose. Blood samples were collected and total hemoglobin (Hb) mass determined using the optimized carbon monoxide (CO) rebreathing method pre- and post-supplementation. BM and total body water (TBW) increased significantly following supplementation by 1.1 ± 1.2 and 1.0 ± 1.2 L (BM, P < 0.01; TBW, P <0.01), respectively. This hyperhydration did not significantly alter plasma volume or any of the doping-relevant blood parameters (e.g., hematocrit, Hb, reticulocytes and total Hb-mass) even when Gly was clearly detectable in urine samples. In conclusion, this study shows that supplementation with hyperhydrating solution containing Gly for 7 days does not significantly alter doping-relevant blood parameters.

Metabolomic profiling of submaximal exercise at a standardised relative intensity in healthy adults

Ten physically active subjects underwent two cycling exercise trials. In the first, aerobic capacity (VO2max) was determined and the second was a 45 min submaximal exercise test. Urine samples were collected separately the day before (day 1) , the day of (day 2), and the day after (day 3) the submaximal exercise test (12 samples per subject). Metabolomic profiling of the samples was carried out using hydrophilic interaction chromatography (HILIC) coupled to an Orbitrap Exactive mass spectrometer. Data were extracted, database searched and then subjected to principle components (PCA) and orthogonal partial least squares (OPLSDA) modelling. The best results were obtained from pre-treating the data by normalising the metabolites to their mean output on days 1 and 2 of the trial. This allowed PCA to separate the day 2 first void samples (D2S1) from the day 2 post-exercise samples (D2S3) PCA also separated the equivalent samples obtained on day 1 (D1S1 and D1S3). OPLSDA modelling separated both the D2S1 and D2S3 samples and D1S1 and D1S3 samples. The metabolites affected by the exercise samples included a range of purine metabolites and several acyl carnitines. Some metabolites were subject to diurnal variation these included bile acids and several amino acids, the variation of these metabolites was similar on day 1 and day 2 despite the exercise intervention on day 2. Using OPLS modelling it proved possible to identify a single abundant urinary metabolite provisionally identified as oxo-aminohexanoic acid (OHA) as being strongly correlated with VO2max when the levels in the D2S3 samples were considered.