Karleigh E. Bradbury's research while affiliated with University of Oregon and other places

Publications (36)

Article
Full-text available
Introduction Exertional heat illnesses remain a major threat to military service members in the United States and around the world. Exertional heat stroke (EHS) is the most severe heat illness, characterized by core hyperthermia and central nervous system dysfunction. Per current Army regulations, iced-sheet cooling (ISC) is the recommended immedia...
Article
The foramen ovale is an essential component of the foetal circulation contributing to oxygenation and carbon dioxide elimination that remains patent under certain circumstances, in ∼ 30% of the healthy adult population, without major negative sequelae in most. Adults with a patent foramen ovale (PFO) have a greater tendency to develop symptoms of a...
Article
Full-text available
Background: The ergogenic effects of supplemental carbohydrate on aerobic exercise performance at high altitude (HA) may be modulated by acclimatization status. Longitudinal evaluation of potential performance benefits of carbohydrate supplementation in the same volunteers before and after acclimatization to HA have not been reported. Purpose: T...
Article
Purpose: This study aimed to characterize HTT specificity and to determine any effect of HA on the outcome. Methods: Thirteen unacclimatized, healthy men (V˙O2peak, 43.0 ± 4.8 mL·kg-1⋅min-1) with no previous history of heat illness completed 8 d of HA using the HTT protocol (40°C/40% RH; 120 min; 5 km·h-1 and 2% grade). Heart rate (HR) and core...
Article
Exercise-heat acclimation (EHA) induces adaptations that improves tolerance to heat exposure. Whether adaptations from EHA can also alter responses to hypobaric hypoxia (HH) conditions remains unclear. This study assessed whether EHA can alter time-trial performance and/or incidence of acute mountain sickness (AMS) during HH exposure. Thirteen sea...
Article
Introduction High altitude missions pose significant challenges to Warfighter medical readiness and performance. Decreased circulating oxygen levels cause a decrease in exercise performance and can cause debilitating symptoms associated with acute mountain sickness, especially with rapid ascent. Acetazolamide (AZ) is known to minimize symptoms of a...
Article
Full-text available
Acetazolamide (AZ) is a medication commonly used to prevent acute mountain sickness (AMS) during rapid ascent to high altitude. However, it is unclear whether AZ use impairs exercise performance; previous literature regarding this topic is equivocal. The purpose of this study was to evaluate the impact of AZ on time-trial (TT) performance during a...
Article
Exposure to hot environments augments cutaneous vasodilation and sweating during exercise compared to these responses in cooler environments. The effects of hypobaric hypoxia on these responses are less clear, as are the effects of heat and simulated altitude, combined. We evaluated the individual and potential additive effects of environmental hea...
Article
Heat and hypobaric hypoxia independently compromise exercise performance, however, their combined impact on exercise performance has yet to be quantified. This study examined the effects of heat, hypobaric hypoxia, and the combination of these environments on self-paced cycling time trial (TT) performance. Twelve subjects (2F, 10M, sea-level (SL) V...
Article
Background: The efficacy of different commercial beverage compositions for meeting oral rehydration therapy (ORT) goals in the treatment of acute dehydration in healthy humans has not been systematically tested. The objective of the study was to compare fluid retention, plasma volume (PV), and interstitial fluid (ISF) volume restoration when using...
Article
Full-text available
Although it has been shown that muscle sympathetic nerve activity increases during high altitude exposure, mechanisms of sympathoexcitation and blood pressure control after return from altitude are not well described. We hypothesized that: (1) living for 12days at 4300m (Pikes Peak, Colorado) would result in increased muscle sympathetic nerve activ...
Article
We hypothesized that muscle sympathetic nerve activity (MSNA) during head-up tilt (HUT) would be augmented during exercise-induced (hyperosmotic) dehydration but not iso-osmotic dehydration via oral diuretic. We studied 26 young healthy subjects (7 F, 19 M) divided into 3 groups: euhydrated (EUH, n = 7), previously exercised in 40°C while maintaini...

Citations

... 15 Updated studies of cooling rates have also shown that immersion in water at room temperature is the preferred method in the event that cold water is unavailable. 16 Applications for field care are still researched, 17 and alternative techniques, which remain effective, have been described as tarpaulin-assisted immersion or immersion in a natural river. [18][19][20] In this context, the objective of this study was to describe the theoretical knowledge of French military practitioners regarding the latest recommendations for the management of EHS and their management of this condition in practice. ...
... 106 107 and it is associated with a high fail rate of false positives. 107 Oestrogen and progesterone fluctuations in the oestrous cycle result in variations in core temperature with women in the luteal phase (eg, high progesterone, lower oestrogen) showing 0.3-0.5 • C increase in core temperature compared with the follicular phase (eg, high oestrogen, low progesterone). Even with this variation in temperature, thermoregulatory responses did not differ throughout the estrous cycle phases. ...
... Bradbury et al. recently published on evidence that exercise performance was not altered with a 500-mg/day dose among healthy men, but others have proposed caution with the application of that finding to all patient populations [155,156]. AZ does not appear to alter hand strength and dexterity as measures of performance when used for altitude sickness [157]. Many athletes are attracted to using acetazolamide when racing at high altitudes thus demonstrating practical perceptions of the existing science [158]. ...
... However, these each have limited effectiveness or present notable side effects: acute altitude descension may not be logistically feasible; acetazolamide has been demonstrated to reduce both cognitive and physical performance, accrue side effects, and does not increase muscle oxygenation [285,287]; erythropoietin may only provide ergogenic effects up to 3500 m [289]; intravenous iron infusion may not be feasible for all individuals [290]; and sildenafil can exaggerate symptoms of mountain sickness including headaches [288]. An increased reliance on, or preference for, CHO for energy provision in hypoxic environments such as moderate-to-high altitude is hypothesised [291], but CHO ingestion does not reliably augment performance at moderate-to-high altitude [292][293][294]. In fact, aerobic exercise performed during acute high altitude exposure elicited lower exogenous glucose oxidation, glucose turnover, and glucose disposal, while concomitant increases in circulating [glucose] and [insulin] suggested a reduced sensitivity of skeletal muscle to glucose uptake in hypoxia compared with exercise in normoxia [295]. ...
... Likewise, there are conflicting data on the subject of AZ's effect to improve or worsen performance at high altitudes [127,130]. Bradbury et al. recently published on evidence that exercise performance was not altered with a 500-mg/day dose among healthy men, but others have proposed caution with the application of that finding to all patient populations [155,156]. AZ does not appear to alter hand strength and dexterity as measures of performance when used for altitude sickness [157]. Many athletes are attracted to using acetazolamide when racing at high altitudes thus demonstrating practical perceptions of the existing science [158]. ...
... , n = 46 between 2010 and 2019(Fukuda et al., 2010;Miyagawa et al., 2011; Basualto-Alarcón et al., 2012;Degache et al., 2012;Kroepfl et al., 2012; Maire r et al., 2012;Schommer et al., 2012;Faiss et al., 2013;Fan et al., 2013;Mairer et al., 2013;Sandfeld et al., 2013;Feriche et al., 2014;Ho et al., 2014; Julia-Sanchez et al., 2014;Kröpfl et al., 2014;Slivka et al., 2014;Trapp et al., 2014;DiPasquale et al., 2015;Seo et al., 2015;Brocherie et al., 2016;Girard et al., 2016;Shrestha and Singh, 2016;Filopoulos et al., 2017;Girard et al., 2017;Klenze et al., 2017;Lira et al., 2017;Lühker et al., 2017;Machado et al., 2017;Matu et al., 2017;Sweeting et al., 2017;Tymko et al., 2017;Wadley et al., 2017;Willis et al., 2017;Alhammoud et al., 2018;Cooke et al., 2018;Lee and Thake, 2018;Angeli et al., 2019;Charkoudian et al., 2019;da Mota et al., 2019;Gronwald et al., 2019;Lei et al. ...
... Alternatively, if the impact of hypoxia on performance is primarily physiological in origin, the impact of music in hypoxia should be similar to that of normoxia (Lloyd et al., 2015). Another potential outcome is that, in cases where hypoxia becomes very severe, it is possible that the hypoxic stressor abolishes the ergogenic benefits of music due to hypoxia likely taking precedence as the dominant factor impacting performance Bradbury et al., 2019). ...
... Studies with VS002 have shown that VS002 administration rapidly rehydrates to increase fluid and electrolyte absorption, tightens the mucosal barrier, thus decreasing local and systemic inflammation, and increases crypt count and villus height, leading to an increase in the surface area of absorption (unpublished data). There is no toxicity associated with VS002 administration and the results of studies in animals and humans suggest that VS002 can serve as a highly safe and effective supportive care in place of standard ORS [8,[39][40][41]. ...
... If differential control persists during prolonged hypoxia, there could be uncoupling of ventilatory and sympathetic acclimatization to high altitude, which raises the possibility that multiple mechanisms account for sympathetic acclimatization to chronic hypoxia. This could explain continuation of heightened sympathetic activity following return to sea level (Hansen & Sander, 2003;Mitchell et al., 2018), which may, in part, be attributed to incomplete reversal of high-altitude pulmonary resistance and elevated pulmonary arterial pressure (Groves et al., 1987;Maufrais et al., 2017). ...
... With absolute hypovolemia, a compensatory elevation in sympathetic nerve output results in peripheral vasoconstriction. The resulting elevation in peripheral vascular resistance can increase arterial blood pressure (afterload), but this is more likely with hyperosmotic hypovolemia dehydration because of a marked influence of elevated osmolality on sympathetic nervous activity [47]. However, if dehydration (absolute hypovolemia) occurs with marked heat stress (relative hypovolemia), the cutaneous vasodilation will offset the increased sympathetic output for compensatory vasoregulation (decrease gut blood flow) and not alter or decrease afterload. ...