ORCID Profile
0000-0001-7677-8634
Current Organisations
Helmholtz Institute for RNA-based Infection Research
,
Julius-Maximilians-Universität Würzburg
,
Liverpool John Moores University School of Sport and Exercise Sciences
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Publications
The prolactin responses to active and passive heating in man
Publisher: Wiley
Date: 11-2005
DOI: 10.1113/EXPPHYSIOL.2005.031294
Abstract: The aim of this study was to compare the prolactin and blood pressure responses at identical core temperatures during active and passive heat stresses, using prolactin as an indirect marker of central fatigue. Twelve male subjects cycled to exhaustion at 60% maximal oxygen uptake (VO2peak) in a room maintained at 33 degrees C (active). In a second trial they were passively heated (passive) in a water bath (41.56 +/- 1.65 degrees C) until core temperature was equal to the core temperature observed at exhaustion during the active trial. Blood s les were taken from an indwelling venous cannula for the determination of serum prolactin during active heating and at corresponding core temperatures during passive heating. Core temperature was not significantly different between the two methods of heating and averaged 38.81 +/- 0.53 and 38.82 +/- 0.70 degrees C (data expressed as means +/- s.d.) at exhaustion during active heating and at the end of passive heating, respectively (P > 0.05). Mean arterial blood pressure was significantly lower throughout passive heating (active, 73 +/- 9 mmHg passive, 62 +/- 12 mmHg P < 0.01). Despite the significantly reduced blood pressure responses during passive heating, during both forms of heating the prolactin response was the same (active, 14.9 +/- 12.6 ng ml(-1) passive, 13.3 +/- 9.6 ng ml(-1) n.s.). These results suggest that thermoregulatory, i.e. core temperature, and not cardiovascular afferents provide the key stimulus for the release of prolactin, an indirect marker of central fatigue, during exercise in the heat.
Exercise thermoregulation and hyperprolactinaemia
Publisher: Informa UK Limited
Date: 15-09-2005
DOI: 10.1080/00140130500101387
Abstract: The anterior pituitary hormone prolactin (PRL), measured in the peripheral blood circulation, reflects alterations in central brain 5-hydroxytryptamine (serotonin) and dopaminergic activity and is used as a marker of 'central fatigue' during active heat exposure. Significant correlations have consistently been found between PRL and core temperature (T(CORE)) during prolonged exercise. There has been no investigation into the relationship between PRL and other key thermoregulatory variables during exercise, such as weighted mean skin (T(SK)) and mean body temperature (T(B)), heat storage (HS), thermal gradient (T(GRAD)), heart rate (HR) and skin blood flow (cutaneous vascular conductance, CVC). Therefore, the aim of this study was to ascertain if a significant relationship exists between PRL and these thermoregulatory variables during prolonged exercise. Nine active male subjects conducted three trials of approximately 60% VO(2peak) at 70-80 rpm for 45 min on a semi-recumbent cycle ergometer at three different ambient temperatures [6 degrees C (Cold), 18 degrees C (Neutral) and 30 degrees C (Hot)] to elicit varying levels of thermoregulatory stress during exercise. Significant differences existed in T(SK), T(B), HS, T(GRAD) and CVC across the environmental conditions (p < 0.001). Core temperature (T(CORE)), HR and PRL were significantly elevated only in Hot (p < 0.05). Moderate correlations were found for T(CORE), T(SK), T(B), HS, T(GRAD), HR and CVC with post-exercise PRL (rho = 0.358-0.749). The end-of-exercise 0.05) but the >38.0 degrees C T(CORE) responses were (rho = 0.845, p < 0.001) significantly related to their corresponding PRL responses. The significant relationships between PRL release and T(SK), T(B), HS, T(GRAD), HR and CVC have extended previous research on T(CORE) and PRL release and indicate an association between these thermoregulatory variables, as well as T(CORE), and serotonergic/dopaminergic activity during prolonged exercise.
Perceptions of Antenatal Exercise in Pregnant Females and the Impact of COVID-19
Publisher: MDPI AG
Date: 26-08-2022
Abstract: Exercise during pregnancy presents many benefits for the mother and baby. Yet, pregnancy is characterised by a decrease in exercise. Studies have reported barriers to antenatal exercise. The coronavirus (COVID-19) pandemic may have further exacerbated barriers to antenatal exercise as pregnant females faced many challenges. Rich, in-depth exploration into pregnant female’s perceived barriers to antenatal exercise during COVID-19 is imperative. Questionnaires reporting physical activity levels were completed by all participants (n = 14). Semi-structured interviews were conducted between November 2020 and May 2021 in the UK. Interviews were analysed using thematic analysis and revealed four main themes: ‘Perceptions of being an active person shaping activity levels in pregnancy’, ‘How do I know what is right? Uncertainty, seeking validation and feeling informed’, ‘Motivators to antenatal exercise’ and ‘A process of adaptations and adjustment’. Findings indicate that the COVID-19 pandemic exacerbated barriers to antenatal exercise and highlight the importance of direct psychosocial support and clear, trustworthy information. Findings also support the fundamental need for better education amongst healthcare professionals regarding antenatal exercise.
Changes in quadriceps femoris muscle perfusion following different degrees of cold-water immersion
Publisher: American Physiological Society
Date: 05-2020
DOI: 10.1152/JAPPLPHYSIOL.00833.2019
Abstract: Using positron emission tomography, we report for the first time muscle perfusion heterogeneity in the quadriceps femoris in response to different degrees of cold-water immersion (CWI). Noxious CWI temperatures (8°C) increase perfusion in the deep quadriceps muscle, whereas superficial quadriceps muscle perfusion is reduced in cooler (15°C) water. Therefore, these data have important implications for the selection of CWI approaches used in the treatment of soft tissue injury, while also increasing our understanding of the potential mechanisms underpinning CWI.
Historical reviews of the assessment of human cardiovascular function: interrogation and understanding of the control of skin blood flow
Publisher: Springer Science and Business Media LLC
Date: 27-11-2019
DOI: 10.1007/S00421-019-04246-Y
Abstract: Several techniques exist for the determination of skin blood flow that have historically been used in the investigation of thermoregulatory control of skin blood flow, and more recently, in clinical assessments or as an index of global vascular function. Skin blood flow measurement techniques differ in their methodology and their strengths and limitations. To examine the historical development of techniques for assessing skin blood flow by describing the origin, basic principles, and important aspects of each procedure and to provide recommendations for best practise. Venous occlusion plethysmography was one of the earliest techniques to intermittently index a limb’s skin blood flow under conditions in which local muscle blood flow does not change. The introduction of laser Doppler flowmetry provided a method that continuously records an index of skin blood flow (red cell flux) (albeit from a relatively small skin area) that requires normalisation due to high site-to-site variability. The subsequent development of laser Doppler and laser speckle imaging techniques allows the mapping of skin blood flow from larger surface areas and the visualisation of capillary filling from the dermal plexus in two dimensions. The use of iontophoresis or intradermal microdialysis in conjunction with laser Doppler methods allows for the local delivery of pharmacological agents to interrogate the local and neural control of skin blood flow. The recent development of optical coherence tomography promises further advances in assessment of the skin circulation via three-dimensional imaging of the skin microvasculature for quantification of vessel diameter and vessel recruitment.
Influence of Cold-Water Immersion on Limb and Cutaneous Blood Flow after Exercise
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2013
Related Organisations
Imperial College London Faculty Of Medicine
Location: United Kingdom of Great Britain and Northern Ireland
Helmholtz Institute For RNA-based Infection Research
Location: Germany
Texas Health Presbyterian Hospital Dallas
Location: United States of America
Liverpool John Moores University School Of Sport And Exercise Sciences
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
No related grants have been discovered for David Low.