Greg Atkinson

Teesside University, Middlesborough, England, United Kingdom

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Publications (230)780.38 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Sleep-disordered breathing is an important comorbidity for several diseases, including stroke. Initial screening tools comprise simple yes/no questions about known risk factors for sleep-disordered breathing, e. g., obesity, sex. But walking speed has not been investigated in this context. We examined the cross-sectional association between walking pace and sleep-disordered breathing in the population-level Multi-Ethnic Study of Atherosclerosis. A sample of 2 912 men and 3 213 women (46-87 years) reported perceived walking pace outside their homes. A walking pace<0.89 m/s was deemed "slow", with ≥ 0.89 m/s considered "average/brisk" according to validated thresholds. Sample prevalences were: sleep apnoea (3.5%), self-reported apnoeas (8.4%), loud snoring (20.5%), daytime tiredness (22.2%) and slow-walking pace (26.9%). The 95% CI risk differences (multivariable-adjusted) for slow vs. faster walking pace were; sleep apnoea (0.4-2.5%), self-reported apnoeas (0.1-3.8%), loud snoring (1.2-8.3%), and daytime tiredness (3.0-7.8%). Risk differences were similar between sexes. The multivariable-adjusted risk ratio indicated that slower walkers had 1.5 (95% CI: 1.0 to 2.1) times the risk of sleep apnoea vs. faster walkers. In conclusion, a slower walking speed was associated with a greater prevalence of sleep-disordered breathing, independently from other common screening factors. Therefore, a simple walking speed question may help consolidate screening for this disorder. © Georg Thieme Verlag KG Stuttgart · New York.
    International Journal of Sports Medicine 06/2015; DOI:10.1055/s-0035-1549856 · 2.37 Impact Factor
  • Greg Atkinson, Alan M Batterham
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    ABSTRACT: Within the "hot topic" of personalised medicine, we scrutinise common approaches for presenting and quantifying individual differences in the physiological response to an intervention. First, we explain how popular plots used to present individual differences in response are contaminated by random within-subjects variation and the regression to the mean artefact. Using a simulated dataset of blood pressure measurements, we show that large individual differences in physiological response can be suggested by some plots and analyses, even when the true magnitude of response is exactly the same in all individuals. Second, we present the appropriate designs and analysis approaches for quantifying the true inter-individual variation in physiological response. It is imperative to include a comparator arm/condition (or derive information from a prior relevant repeatability study) to quantify true inter-individual differences in response. The most important statistic is the standard deviation of changes in the intervention arm which should be compared with the same standard deviation in the comparator arm, or from a prior repeatability study in the same population conducted over the same duration as the particular intervention. Only if the difference between these standard deviations is clinically relevant is it logical to go on to explore any moderators or mediators of the intervention effect that might explain the individual response. To date, very few researchers have compared these standard deviations before making claims about individual differences in physiological response and their importance to personalised medicine. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Experimental physiology 03/2015; 100(6). DOI:10.1113/EP085070 · 2.87 Impact Factor
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    ABSTRACT: To quantify the relationship between daily training load and a range of potential measures of fatigue in elite soccer players during an in-season competitive phase (17-days). Total high-intensity running distance (THIR), perceived ratings of wellness (fatigue, muscle soreness, sleep quality), counter-movement jump height (CMJ), post-exercise heart rate recovery (HRR) and heart rate variability (Ln rMSSD) were analysed during an in-season competitive period (17 days). General linear models were used to evaluate the influence of daily fluctuation in THIR distance on potential fatigue variables. Fluctuations in fatigue (r=-0.51; large; P<0.001), Ln rMSSD (r=-0.24; small; P=0.04), and CMJ (r=0.23; small; P=0.04) were significantly correlated with fluctuations in THIR distance. Correlations between variability in muscle soreness, sleep quality and HRR and THIR distance were negligible and not statistically significant. Perceived ratings of fatigue and heart rate variability were sensitive to daily fluctuations in THIR distance in a sample of elite soccer players. Therefore, these particular markers show particular promise as simple, non-invasive assessments of fatigue status in elite soccer players during a short in-season competitive phase.
    International journal of sports physiology and performance 02/2015; DOI:10.1123/ijspp.2015-0004 · 2.68 Impact Factor
  • Greg Atkinson, Alan M Batterham
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    ABSTRACT: In 2010, the American College of Cardiology Foundation and American Heart Association could not recommend brachial artery percentage flow-mediated dilation (FMD%) for risk assessment of coronary artery disease (CAD) in asymptomatic adults. We aimed to scrutinise past and recently published findings regarding FMD% in this same context of clinical utility and conclude that (1) the question of whether brachial FMD% is a suitable substitute for coronary vasodilation is addressed by method agreement statistics rather than the correlation coefficients that have been reported in past studies. Also, the much-repeated view that brachial FMD% and coronary vasodilation are "closely related" is not entirely justified, even before the influence of baseline lumen diameters on this relationship is accounted for; (2) along with the specialist training and the considerable time (≥1 h) that is required for the FMD% protocol, the error in individual measurements and population reference ranges is too large for clinical decisions to be robust on individual patients; (3) many interventions that are proposed to change FMD% also change baseline artery diameter, which can bias estimates of any intervention effects on the flow-mediated response per se, and (4) the FMD% index generates spurious correlations between shear rate, artery diameter and endothelial function, which may help to explain the apparent paradoxes of FMD% being higher in obese people and lower in athletes. In conclusion, the clinical relevance of brachial artery flow-mediated dilation is unclear at present. The dependence of the chosen index, FMD%, on initial artery size has contributed to this lack of clarity.
    Current Hypertension Reports 02/2015; 17(2):514. DOI:10.1007/s11906-014-0514-0 · 3.90 Impact Factor
  • Clinical Physiology and Functional Imaging 12/2014; DOI:10.1111/cpf.12211 · 1.33 Impact Factor
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    ABSTRACT: Recent laboratory experiments on rodents have increased our understanding of circadian rhythm mechanisms. Typically, circadian biologists attempt to translate their laboratory-based findings to treatment of jet lag symptoms in humans. We aimed to scrutinise the strength of the various links in the translational pathway from animal model to human traveller. First, we argue that the translation of findings from pre-clinical studies to effective jet lag treatments and knowledge regarding longer-term population health is not robust, e.g. the association between circadian disruption and cancer found in animal models does not translate well to cabin crew and pilots, who have a lower risk of most cancers. Jet lag symptoms are heterogeneous, making the true prevalence and the effects of any intervention difficult to quantify precisely. The mechanistic chain between in vitro and in vivo treatment effects has weak links, especially between circadian rhythm disruption in animals and the improvement of jet lag symptoms in humans. While the number of animal studies has increased exponentially between 1990 and 2014, only 1-2 randomised controlled trials on jet lag treatments are published every year. There is one relevant Cochrane review, in which only 2-4 studies on melatonin, without baseline measures, were meta-analysed. Study effect sizes reduced substantially between 1987, when the first paper on melatonin was published, and 2000. We suggest that knowledge derived from a greater number of human randomised controlled trials would provide a firmer platform for circadian biologists to cite jet lag treatment as an important application of their findings.
    Arbeitsphysiologie 10/2014; 114(12). DOI:10.1007/s00421-014-3026-3 · 2.30 Impact Factor
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    ABSTRACT: We investigated the effects of evening bright light on the circadian timing of core temperature and morning exercise performance under conditions of high thermal stress. At 20:00 h, 8 males were exposed to a standardised light protocol and thereafter to either polychromatic bright light (2 500 lux at 50 cm, BL) or no light (0 lux, NL) for 30 min. The following morning, intermittent cycling exercise was undertaken followed by a 10 km time-trial in an environmental chamber set to 35°C and 60% relative humidity. Core body temperature was measured throughout. Data were analysed using a within-subjects model and presented as mean±SD. Time of the sleep-trough in core temperature occurred ~1.75 h later following BL (P=0.07). Prior to time-trial, core temperature was 0.27±0.42°C lower in BL (95%CI: -0.02 to 0.57, P=0.07). The time-trial was completed 1.43±0.63 min (0.98-1.87) faster in BL (P=0.001). Post time-trial, intestinal temperature was 38.21±0.56°C (37.84-38.57) in BL compared to 38.64±0.42°C (38.34-38.93) in NL (P=0.10). These data provide the first evidence that a 30-min exposure to bright light prior to sleep can influence exercise performance under hot conditions during the subsequent early morning.
    International Journal of Sports Medicine 10/2014; 36(02). DOI:10.1055/s-0034-1389970 · 2.37 Impact Factor
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    ABSTRACT: The incidence of vasovagal syncope is more common in the morning. Previous researchers have reported negligible diurnal variation in the physiological responses associated with initial orthostatic hypotension (IOH). Nevertheless, physical activity and sleep prior to morning and afternoon test times have not been controlled and may influence the findings. We designed a semi-constant routine protocol to examine diurnal variation in cardiorespiratory and cerebrovascular responses to active standing.
    Arbeitsphysiologie 10/2014; 115(2). DOI:10.1007/s00421-014-3010-y · 2.30 Impact Factor
  • Greg Atkinson
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    ABSTRACT: A ratio index (FMD%) is used ubiquitously to scale (by simple division) brachial artery flow-mediated dilation (Ddiff) in direct proportion to baseline diameter (Dbase). It is now known that Ddiff is inversely proportional to Dbase rendering FMD% wholly inappropriate. Consequently, FMD% is still substantially dependent on Dbase. Although this problem is grounded in statistics, normalization of FMD% for the change in arterial shear rate (ΔSR) has been proposed to remove this Dbase-dependency. It was hypothesized that, if the flow-mediated response is scaled properly to Dbase in the first place, shear rate normalization would not be needed to remove Dbase-dependency. Dedicated software (Digitizelt) was employed to extract the data from a seminal study on FMD% normalization. The underlying allometric relationship between Dbase and peak diameter (Dpeak) was described. The re-analyses revealed that the absolute change in arterial diameter was strongly inversely proportional to Dbase (r= − 0.7, P < 0.0005). The allometric exponent for the Dbase–Dpeak relationship was 0.82 (95% CI: 0.78–0.86) rather than the value of 1 needed for appropriate use of FMD%. The allometric approach completely eliminated the originally reported dependency on Dbase without any need for ΔSR normalization (r=0.0, P=0.96). The correlation between ΔSR and FMD% reduced from 0.69 to 0.37, when adjusted for Dbase. In conclusion, this new re-analysis of data from an influential study demonstrates that the FMD%–Dbase correlation is caused by the inappropriate size-scaling properties of FMD% itself. Removal of Dbase-dependency via FMD%/ΔSR normalization is not essential at all if allometric scaling is applied to isolate the flow-mediated response in the first place. Consequently, the influence of ΔSR on this properly scaled response can also be isolated and quantified accurately without the confounding influence of Dbase.
    Physiological Measurement 08/2014; 35(9):1825. DOI:10.1088/0967-3334/35/9/1825 · 1.62 Impact Factor
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    ABSTRACT: The aim of the study was to compare 3-year changes in physical performance between junior soccer players selected for an elite academy and age-matched controls. The 3-year changes in indicators of the physical performance were quantified in 12-16-year-old Premier League Academy (n=27) and non-academy soccer players (n=18). Data were analysed with an age-group×competitive level general linear model, covariate-adjusted for initial performance level and change in maturation. Covariate adjusted mean±SD changes were greater (standardised effect size>0.7) for the academy players in terms of countermovement jump (7.3±2.6 vs. 5.4±2.5 cm), 10 m sprint (- 0.15±0.05 vs. - 0.10±0.04 s), 20 m sprint (- 0.30±0.16 s vs. - 0.15±0.13 s), agility (- 0.19±0.01 s vs. - 0.08±0.08 s), repeated sprint (- 0.60±0.26 s vs. - 0.41±2.1 s) and intermittent endurance capacity (1 128±406 vs. 315±370 m). These data indicate that a 3-year programme of training in an elite soccer academy is associated with greater changes in physical performance indicators independently from the initial performance level of the child and change in maturation over the same period of time.
    International Journal of Sports Medicine 07/2014; 35(13). DOI:10.1055/s-0034-1375616 · 2.37 Impact Factor
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    ABSTRACT: Introduction: The individual internal response to an external training load (TL) is the important stimulus for mediating longer-term adaptation. The session rating of perceived exertion (sRPE) is widely used as an indicator of the internal training response in team sports such as soccer (3). Markers of external TL can predict sRPE during rugby training (4). It is unknown whether this is so during soccer training (1). Therefore, we aimed to identify the external TL markers that are most influential of sRPE during elite soccer training. Methods: Twenty-two soccer players (four central defenders, three wide defenders, six central midfielders, three wide midfielders and six attackers) competing in the English Premier League were monitored. The TL data (sRPE and global positioning system @ 10Hz) were collected during 1892 individual training sessions over an entire in-season competitive period. A multivariate-adjusted within-subjects model was employed to quantify the correlations between sRPE and sRPE-TL and various measures of external training intensity and TL respectively (2). Results & Discussion: Expert knowledge and a colinearity r < 0.5 were used initially to select the external training variables for the final analysis. Total high-speed running distance (HSR; >14.4 km·h1), number of impacts and accelerations >3 m•s-2 remained in the final multivariate model (p<0.001). The adjusted correlations with sRPE were r=0.14, r=0.09 and r=0.25 for HSR, impacts and accelerations respectively. For sRPE-TL, the correlations were r=0.11, r=0.45 and r=0.37 respectively. Conclusion: The external load measures that were found to be predictive of sRPE in soccer training were HSR distance, and the number of impacts and accelerations.
    4th World Conference on Science and Soccer (WCSS), Portland, (Oregon, USA); 06/2014
  • Greg Atkinson, Alan M Batterham
    Vascular Medicine 05/2014; 19(2):142-143. DOI:10.1177/1358863X14528566 · 1.73 Impact Factor
  • 04/2014; 44(8). DOI:10.1007/s40279-014-0183-9
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    ABSTRACT: To examine the effects of a simulated dawn during the last 30 min of sleep on the subsequent dissipation of sleep inertia and changes in simulated work and physical performance. Eight participants, who reported difficulty with morning waking, were administered in a random order to a control (C) and a dawn simulation (DS) trial (starting 30 min prior to waking). Subjective ratings of sleep quality and alertness were obtained alongside measures of cognitive performance (addition and reaction time tasks measured at 5, 30 and 75 min after waking at habitual workday times). Physical performance was also measured 35 min after waking using a self-paced cycling protocol. After waking in DS, perceived sleep quality was 1.16 ± 0.89 (p = 0.01) points higher compared with C. Ratings of alertness were significantly higher in DS than C throughout the testing period (p = 0.04). Cognitive performance improved in both trials as time awake increased (p < 0.0005). On average, participants completed a greater number of additions in DS compared with C (69.5 ± 15.3 vs 66.9 ± 16.7, p = 0.03). Reaction times were also faster in DS compared with C (0.81 ± 0.07 s vs 0.86 ± 0.06 s, p < 0.0005). The self-paced time-trial was completed 21.4 s (4.7 %) quicker in DS (p = 0.07). These data provide the first evidence that light exposure during the last 30 min of habitual sleep can increase subjective alertness and improve both cognitive and physical performance after waking.
    Arbeitsphysiologie 02/2014; 114(5). DOI:10.1007/s00421-014-2831-z · 2.30 Impact Factor
  • Greg Atkinson, Alan M Batterham
    International journal of cardiology 01/2014; 172(1). DOI:10.1016/j.ijcard.2013.12.264 · 6.18 Impact Factor
  • Greg Atkinson, Alan M Batterham
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    ABSTRACT: The percentage flow-mediated dilation index (FMD%) scales the increase in arterial diameter (Ddiff) as a constant proportion of baseline artery diameter (Dbase). We have demonstrated, albeit with small samples, that the scaling properties of FMD% can lead to biased inferences on endothelial dysfunction. Therefore, we aimed to investigate the underlying rationale and potential bias of FMD% using a selection of new examples from the large (n = 3499) and diverse Multi-Ethnic Study of Atherosclerosis (MESA). In this dataset, we found that smaller values of Ddiff are associated with larger values of Dbase, which contradicts the scaling properties of FMD%. Consequently, FMD% 'over-scales' and naturally generates an even stronger negative correlation between itself and Dbase. Using a data simulation, we show that this FMD%-Dbase correlation can be a statistical artefact due to inappropriate scaling. The new examples we present from MESA indicate that FMD% biases the differences in flow-mediated response between men and women, Framingham risk score categories, and diseased and healthy people. We demonstrate how FMD%, as an exposure for predicting cardiovascular disease, is confounded by its dependency on Dbase, which itself could be clinically important. This critical review, incorporating an allometric analysis of a large dataset, suggests that the FMD% index has a less-than-clear rationale, can itself generate the Dbase-dependency problem, provides biased estimates of differences in the flow-mediated response, complicates the interpretation of the flow-mediated protocol and clouds the causal pathway to vascular disease. These interpretative problems can be resolved by applying accepted allometric principles to the flow-mediated response.
    Vascular Medicine 10/2013; 18(6). DOI:10.1177/1358863X13508446 · 1.73 Impact Factor
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    ABSTRACT: Background: Individuals with a spinal cord injury (SCI) demonstrate altered circadian variation in thermoregulatory control. Recently, we reported that tetraplegia is associated with a blunted release of melatonin in the evening. In order to examine whether this finding relates to circadian thermoregulation, we compared the correlations between evening changes in melatonin, core and skin temperature between thoracic and cervical SCI and able-bodied participants. Methods: In 10 able-bodied, 9 paraplegic and 8 tetraplegic participants, we measured, between 1900 and 2300 h, core temperature, proximal skin temperature (above and below the level of the lesion) and physical activity. Salivary melatonin was also sampled during this period and analyzed using enzyme linked immunosorbant assay. Results: Between 1900 and 2300 h, core and upper limb skin temperature gradually decreased in all groups (p = 0.01). A significant group × time interaction was evident in lower body skin temperature (p = 0.03). Lower body skin temperature was significantly higher in able-bodied controls compared with tetraplegics between 1900 and 2000 h (p < 0.05). In able-bodied and paraplegic participants, the changes in melatonin and core temperature were inversely correlated (r = -0.44 and -0.54, respectively, both p = 0.01). Melatonin and mean skin temperature changes were also inversely correlated (able-bodied controls: r = -0.24; p = 0.05 and paraplegics: r = -0.30; p= 0.02). Conclusion: The inverse correlation between evening changes in melatonin and thermoregulation is of a similar magnitude in paraplegic and able-bodied controls. In contrast, changes in skin temperature, below the level of the lesion, are unrelated to changes in melatonin in tetraplegics.
    Chronobiology International 10/2013; 31(2). DOI:10.3109/07420528.2013.833516 · 2.88 Impact Factor
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    ABSTRACT: In keeping with this review-series theme, we question whether the morning surge in blood pressure (MSBP) is a benign response to the physiological challenges during the first 3 h after waking, or is it clinically important? Therefore, we scrutinise the circadian-related mechanisms, the measurement methods and the prognostic value of the MSBP. The MSBP is relatively small (<2 mmHg) under constant routine conditions. Nevertheless, the blood pressure response to exercise can be 8-14 mm Hg greater in the morning vs. afternoon, even when prior sleep is controlled. Systematic bias between MSBP methods can be >10 mmHg. The "sleep-trough" method provides the largest MSBP (≈25 mmHg), but the sensitivity of MSBP to a treatment/intervention depends largely on its repeatability. The repeatability standard deviation (SD) for most MSBP methods is ≈8 mm Hg. While the magnitude of this SD precludes the use of MSBP for diagnostic decisions on individual patients, sample sizes for future intervention studies may be feasible, depending on the minimal clinically important difference in MSBP. This difference is somewhat unclear given that a large MSBP has recently been reported to predict a reduced, rather than a higher, risk of cardiovascular disease, although this particular study has been criticised. The MSBP is also naturally correlated to changes in physical activity and nocturnal "dipping" status. Therefore, it is important to account for these potential confounders of the MSBP, so that more precise knowledge about its clinical significance is gained, thereby providing a sound rationale for physiological investigation and translational research.
    Arbeitsphysiologie 07/2013; 114(3). DOI:10.1007/s00421-013-2692-x · 2.30 Impact Factor
  • Heart, Lung and Circulation 07/2013; 23(1). DOI:10.1016/j.hlc.2013.06.005 · 1.17 Impact Factor
  • K Marrin, B Drust, W Gregson, G Atkinson
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    ABSTRACT: A melatonin-mediated reduction in body temperature could be useful as a "pre-cooling" intervention for athletes, as long as the melatonin dose is optimised so that substantial soporific effects are not induced. However, the melatonin-temperature dose-response relationship is unclear in humans. Individual studies have involved small samples of different sexes and temperature measurement sites. Therefore, we meta-analysed the effects of exogenous melatonin on body core temperature to quantify the dose-response relationship and to explore the influence of moderating variables such as sex and measurement site. Following a literature search, we meta-analysed 30 data-sets involving 193 participants and 405 ingestions of melatonin. The outcome was the mean difference (95 % confidence limits) in core temperature between the melatonin and placebo-controlled conditions in each study, weighted by the reciprocal of each standard error of the difference. The mean (95 % confidence interval) pooled reduction in core temperature was found to be 0.21 °C (0.18-0.24 °C). The dose-response relationship was found to be logarithmic (P < 0.0001). Doses of 0-5 mg reduced temperature by ~0.00-0.22 °C. Any further reductions in temperature were negligible with doses >5 mg. The pooled mean reduction was 0.13 °C (0.05-0.20 °C) for oral temperature vs 0.26 °C (0.20-0.32 °C) for tympanic and 0.22 °C (0.19-0.25 °C) for rectal temperature. In conclusion, our meta-regression revealed a logarithmic dose-response relationship between melatonin and its temperature lowering effects. A 5-mg dose of melatonin lowered core temperature by ~0.2 °C. Higher doses do not substantially increase this hypothermic effect and may induce greater soporific effects.
    Arbeitsphysiologie 06/2013; 113(9). DOI:10.1007/s00421-013-2668-x · 2.30 Impact Factor

Publication Stats

8k Citations
780.38 Total Impact Points

Institutions

  • 2012–2015
    • Teesside University
      • School of Health and Social Care
      Middlesborough, England, United Kingdom
    • University of Liverpool
      Liverpool, England, United Kingdom
  • 2013
    • Cleveland State University
      Cleveland, Ohio, United States
  • 1993–2013
    • Liverpool John Moores University
      • • Research Institute for Sport and Exercise Sciences (RISES)
      • • School of Sport and Exercise Sciences
      Liverpool, ENG, United Kingdom
  • 2003–2004
    • Loughborough University
      Loughborough, England, United Kingdom
  • 2001
    • Durham University
      Durham, England, United Kingdom