James David Cotter

• PhD
• Professor at University of Otago

Military personnel are required to operate in hot environments upon short notice. To preserve performance an elevated thermal tolerance could be maintained prior to deployment using heat acclimation (HA) followed by intermittent heat exposure (IHE). In a randomised manner, 19 participants completed 5 d of passive, post-exercise HA in either sauna o...

Seasonal heat acclimatization is known to enhance autonomic thermoeffector responses, whereas the behavioural response following seasonal heat acclimatization remains unknown. We investigated whether seasonal heat acclimatization would alter autonomic and behavioural thermoregulatory responses. Sixteen healthy participants (eight males and eight fe...

Background: Prehabilitation is the process of optimising patient functional capacity and health status in preparation for surgery. Supervised prehabilitation is considered gold standard, however it is resource intensive. The purpose of this study was to examine the effect of a personalised home-based exercise intervention, for maintaining cardiores...

Background: The purpose of the study was to examine the acute and adaptive analgesic effects of two separate therapies-hot-water immersion and upper-limb high-intensity interval exercise (HIIE)-in patients with severe lower-limb osteoarthritis. Methods: Eligible and consenting participants scheduled for hip or knee arthroplasty were randomized to h...

Objective Preoperative exercise training, or prehabilitation, aims to optimize cardiorespiratory fitness before surgery to reduce the risk of adverse perioperative events and delayed recovery. However, traditional exercise such as walking and cycling can be difficult for people with degenerative joint diseases of the lower limbs, such as osteoarthr...

Exercise is painful and difficult to perform for patients with severe lower-limb osteoarthritis; consequently, reduced physical activity contributes to increased cardiometabolic disease risk. The aim of this study was to characterize the acute and adaptive cardiovascular and metabolic effects of two low or no impact therapies in patients with sever...

Endurance exercise induces cardiovascular adaptations; the athletic phenotypes of the heart and arteries are well characterised, but few studies have investigated the effects of chronic exercise on the venous system. The aim of this study was to describe the anatomy and function of lower limb deep and superficial veins in athletes compared to contr...

Intermittent fasting and exercise provide neuroprotection from age‐related cognitive decline. A link between these two seemingly distinct stressors is their capability to steer the brain away from exclusively glucose metabolism. This cerebral substrate switch has been implicated in upregulating brain‐derived neurotrophic factor (BDNF), a protein in...

Many studies have reported that ambient heat stress increases physiological and perceptual strain and impairs endurance exercise, but effects of air temperature per se remain almost unexamined. Most studies have used matched relative humidity, thereby exponentially increasing absolute humidity (water content in air) concurrently with temperature. A...

Epidemiological evidence has highlighted a strong relationship between cardiorespiratory fitness and surgical outcomes; specifically, fitter patients possess heightened resilience to withstand the surgical stress response. This narrative review draws on exercise and surgical physiology research to discuss and hypothesise the potential mechanisms by...

Physical activity is the most common source of heat strain for humans. The thermal strain of physical activity causes over-breathing (hyperventilation) and this has adverse physiological repercussions. The mechanisms underlying heat-induced hyperventilation during exercise are unknown, but recent evidence supports a primary role of carotid body hyp...

Purpose: This study assessed whether increasing sodium in a sports drink above that typical (~ 20 mmol L-1) affects plasma sodium and volume responses during prolonged exercise in the heat. Methods: Endurance trained males (N = 11, 36 ± 14 y, 75.36 ± 5.30 kg, [Formula: see text]O2max 60 ± 3 mL min-1 kg-1) fulfilled requirements of the study incl...

Humans hyperventilate under heat and cold strain. This hyperventilatory response has detrimental consequences including acid–base dysregulation, dyspnoea, decreased cerebral blood flow and accelerated brain heating. The ventilatory response to hypoxia is exaggerated under whole‐body heating and cooling, indicating that altered carotid body function...

Teaching traditionally asserts that the arterial pressure pulse is dampened across the capillary bed to the extent that pulsatility is non-existent in the venous circulation of the lower limbs. Herein, we present evidence of transmission of arterial pulsations across the capillary network into perforator veins in the lower limbs of healthy, heat-st...

To mitigate the effects of heat during operations in hot environments, military personnel will likely benefit from heat acclimation (HA) conducted prior to deployment. Using post-exercise, passive heating, 25 participants completed a 5 d HA regime in sauna (70 °C, 18% RH) or hot-water immersion (HWI) (40 °C) for ≤40 min, preceded and followed by a...

New findings: What is the central question of this study? What are the profiles of acute physiological and psychophysical strain during and in recovery from different modes of heating, and to what extent do these diminish after repeated exposure? What is the main finding and its importance? Mode of heating affects the strain profiles during heat s...

New findings: Central question to the study? Are primary indices of heat adaptation (e.g., expansion of plasma volume and reduction in resting core temperature) differentially affected by the three major modes of short-term heat acclimation, i.e., exercise in the heat, hot water immersion and sauna? Main finding and its importance? The three modes...

We investigated whether substituting the final half within 60-min bouts of exercise with passive warm or cold water immersion would provide similar or greater benefits for cardiometabolic health. Thirty healthy participants were randomized to two of three short-term training interventions in a partial crossover (12 sessions over 14–16 days, 4 week...

Objective The purpose of the present study was to determine the neuroendocrine response after a thoracic spinal manipulation in people with Achilles tendinopathy. Methods This was a randomized 2-sequence, 2-period crossover trial. A total of 24 participants, mean (standard deviation) age of 48 (7) years, with a diagnosis of Achilles tendinopathy (...

Background Military personnel often deploy into hot environments that impose substantial strain on physical and cognitive performance. Hot environments can present as arid or humid and occur in different terrains, requiring different operational approaches. The aim of this study was to characterise the physiological, cognitive and perceptual strain...

Introduction: Hand-held isometric dynamometry is a convenient alternative to gold standard isokinetic dynamometry for the assessment of skeletal muscle strength. The purpose of this study was to quantify the absolute and relative reliability of hand-held dynamometry, for the measurement of lower-limb isometric strength in patients with severe hip a...

Key points The human brain is particularly vulnerable to heat stress; this manifests as impaired cognition, orthostatic tolerance, work capacity and eventually, brain death. The brain's limitation in the heat is often ascribed to inadequate cerebral blood flow (CBF), but elevated intracranial pressure is commonly observed in mammalian models of hea...

Purpose Cognition can be impaired during exercise in the heat, potentially contributing to military casualties. To our knowledge, the independent role of elevated core temperature during exercise has not been determined. The aim of the current study was to evaluate effects of elevated core temperature on cognition during physically encumbering, hea...

The objective of this study was to compare acute effects of prolonged sitting, prolonged standing and sitting interrupted with regular activity breaks on vascular function and postprandial glucose metabolism. In a randomized cross-over trial, 18 adults completed: 1. Prolonged Sitting; 2. Prolonged Standing and 3. Sitting with 2-min walking (5 km/h,...

Key points Cognitive function depends on adequate cerebrovascular perfusion and control. However, it is unknown whether acutely‐reduced cerebral blood flow (CBF) impairs cognition in healthy adults. In the present study, we used a placebo‐controlled, single‐blinded, randomized cross‐over design to test the hypothesis that acutely‐reduced CBF (using...

Acute exposure to heat, such as that experienced by people arriving into a hotter or more humid environment, can compromise physical and cognitive performance as well as health. In military contexts heat stress is exacerbated by the combination of protective clothing, carried loads, and unique activity profiles, making them susceptible to heat illn...

New findings: What is the central question of this study? How does resistance exercise affect peripheral haemodynamics in the active and inactive limb? What is the main finding and its importance? Preliminary data indicate that resistance exercise increases flow and shear rate in the active limb transiently. The same exercise has minimal, short-la...

PurposeCognition, cerebral blood flow (CBF) and its major regulator (i.e., arterial CO2), increase with submaximal exercise and decline with severe exercise. These responses may depend on fitness. We investigated whether exercise-related changes in cognition are mediated in part by concomitant changes in CBF and CO2, in ten active (26 ± 3 years) an...

Cardiopulmonary exercise testing is performed increasingly for cardiorespiratory fitness assessment and pre‐operative risk stratification. Lower limb osteoarthritis is a common comorbidity in surgical patients, meaning traditional cycle ergometry‐based cardiopulmonary exercise testing is difficult. The purpose of this study was to compare cardiopul...

The increasing number of older adults has seen a corresponding growth in those affected by neurovascular diseases, including stroke and dementia. Since cures are currently unavailable, major efforts in improving brain health need to focus on prevention, with emphasis on modifiable risk factors such as promoting physical activity. Moderate‐intensity...

PurposeRecent studies have determined that ambient humidity plays a more important role in aerobic performance than dry-bulb temperature does in warm environments; however, no studies have kept humidity constant and independently manipulated temperature. Therefore, the purpose of this study was to determine the contribution of dry-bulb temperature,...

Both cognitive function and cerebral blood flow (CBF) decline across the lifespan. However, the relation between them remains unclear, particularly in the context of aging. Furthermore, fitness improves both cognition and CBF, and may be associated with preserved cognitive and cerebrovascular function in an older population. Purpose The aims of th...

Purpose To examine the interactive effects of VM and isometric resistance exercise on cerebral haemodynamics. Methods Eleven healthy participants (mean ± SD 28 ± 9 years; 2 females) completed 20-s bilateral isometric leg extension at 50% of maximal voluntary contraction with continued ventilation (RE), a 20-s VM at mouth pressure of 40 mmHg (VM),...

Key points Thermal and hypoxic stress commonly coexist in environmental, occupational and clinical settings, yet how the brain tolerates these multi‐stressor environments is unknown Core cooling by 1.0°C reduced cerebral blood flow (CBF) by 20–30% and cerebral oxygen delivery (CDO2) by 12–19% at sea level and high altitude, whereas core heating by...

Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous...

Both acute and regular exercise influence vascular and cognitive function. Upright aquatic exercise increases mean middle cerebral artery blood velocity (MCAvmean ) and has been suggested as favorable for cerebrovascular adaptations. However, MCAvmean has not been reported during swimming. Thus, we examined the cerebrovascular and cognitive effects...

Tokyo 2020 will likely be the most heat stressful Olympics to date, so preparation to mitigate the effects of humid heat will be essential for performance in several of the 33 sports. One key consideration is heat acclimation (HA); the repeated exposure to heat to elicit physiological and psychophysical adaptations that improve tolerance and exerci...

New findings: • What is the central question of this study? Does habitual resistance and endurance exercise modify dynamic cerebral autoregulation? • What is the main finding and its importance? To the authors' knowledge, this is the first study to directly assess dynamic cerebral autoregulation in resistance-trained individuals, and potential dif...

New findings: The effects of acute mental stress on the mechanisms regulating cerebral blood flow remain unclear. The major novel findings of this study were that: 1) high mental stress and hypercapnia had an interactive effect on mean middle cerebral artery blood velocity; 2) high mental stress altered the regulation of cerebral blood flow; 3) th...

Peripheral arterial disease (PAD) is characterized by lower limb atherosclerosis impairing blood supply and causing walking-induced leg pain or claudication. Adherence to traditional exercise training programs is poor due to these symptoms despite exercise being a mainstay of conservative treatment. Heat therapy improves many cardiovascular health...

A growing body of evidence indicates regular physical activity benefits older adults’ cognitive functioning, particularly when a high level of cognitive control is required. Recent research has pointed to improved cerebrovascular function as one mechanism through which such benefits might arise. This study built on previous research by investigatin...

Protocol for a systematic review to determine the effectiveness of spinal manipulation on eliciting changes in ANS activity in humans.

Human physiological responses to heat, cold, hypoxia, microgravity, hyperbaria, hypobaria and fasting are well studied in isolation. However, in the natural world these stressors are often combined or experienced sequentially (Tipton, 2012). Studies examining human responses to these more realistic, yet relatively complex, circumstances remain spar...

Open-water swimming (OWS) is undertaken in diverse bodies of water and climatic locations, over distances mostly between 1.5 and 88 km. OWS provides a unique and potentially hazardous thermoregulatory challenge for multiple reasons, but the lack of information on physiological, performance and health effects is conspicuous and surprising. At least...

Key points One in two female athletes chronically take a combined, monophasic oral contraceptive pill (OCP). Previous thermoregulatory investigations proposed that an endogenous rhythm of the menstrual cycle still occurs with OCP usage. Forthcoming large international sporting events will expose female athletes to hot environments differing in thei...

In this poster, the changes in Tissue Oxygenation Index (TOI) in calf muscle following a thoracic spinal manipulation in people with AT was presented.

Temperature of the skin (TSk) and core (TC) play key roles in sleep–wake regulation. The diurnal combination of low TSk and high TC facilitates alertness, whereas the transition to high TSk and low TC correlates with sleepiness. Sleepiness and deteriorating vigilance are induced with peripheral warming, whereas peripheral cooling appears to transie...

The application of molecular techniques to exercise biology has provided novel insight into the complexity and breadth of intracellular signaling networks involved in response to endurance-based exercise. Here we discuss several strategies that have high uptake by athletes and, on mechanistic grounds, have the potential to promote cellular adaptati...

Acute mental stress has been shown to cause peripheral vascular dysfunction, but its effect on cerebrovasculature is unclear. Thus, the aim of this study was to examine cerebrovascular and hemodynamic responses to mental stress. Sixteen healthy participants (aged 23±4 y, 5 female) completed seated conditions of baseline, followed by low and high me...

The purpose of this study was to identify the dose-dependent effects of heat strain and orthostasis (via lower-body negative pressure; LBNP), with and without mild hypohydration, on systemic function and cerebral perfusion. Eleven males (Mean ±SD: 27 ±7 y; body mass 77 ±6 kg), resting supine in a water-perfused suit, underwent progressive passive h...

Spinal Manipulation (SM) is a common therapeutic technique used by a multitude of practitioners (Physiotherapists, Osteopaths and Chiropractors) to reduce pain and improve physical function. Various studies have explored the mechanisms through which SM acts. One such mechanism is the liberation of biochemical markers following a SM. Therefore, a sy...

Heat is a major stressor during exercise, though its value in driving adaptation is not well understood. Muscle heating can upregulate pathways facilitating protein synthesis and could thereby enhance effects of exercise training, however, few studies have investigated this possibility. We examined whether heating active muscle during resistance tr...

Exercise and exogenous heat each stimulate multiple adaptations, but their roles are not well delineated, and that of the related stressor, dehydration, is largely unknown. While severe and prolonged hypohydration potentially “silences” the long-term heat acclimated phenotype, mild and transient dehydration may enhance cardiovascular and fluid-regu...

Example progression (from left to right, starting top left corner) of exercises during the 70-min callisthenics period of the exercise protocol.

The effect of heat stress and hydration status on the systolic (sBP; A), diastolic (dBP, B) and mean arterial blood pressure (MAP, C) response to the 90-min exercise condition, and in recovery. Data presented are group mean with individual values overlaid. m denotes male participant. For statistical significance please refer to Figure 5 in the Manu...

Purpose: To determine the effects of heated resistance exercise on thermal strain, neuromuscular function and hormonal responses in power athletes. Methods: Sixteen (n = 8 female; 8 male) highly trained power athletes completed a combined strength and power resistance exercise session in hot (HOT ~30 °C) and temperate (CON ~20 °C) conditions. Hu...

Spinal manipulation, a common therapeutic technique used by physiotherapists may have widespread effects on various biochemical markers such as pain markers, inflammatory markers and endocrine markers. The aim of this systematic review was to determine the effectiveness of spinal manipulation in influencing various biochemical markers in healthy an...

As major sporting events are often held in hot environments, increased interest in ways of optimally heat acclimating athletes to maximise performance has emerged. Heat acclimation involves repeated exercise sessions in hot conditions that induce physiological and thermoregulatory adaptations that attenuate heat-induced performance impairments. Cur...

Study Design Controlled laboratory study. Background Spinal manipulation (SM) can trigger a cascade of responses involving multiple systems, including the sympathetic nervous system and the endocrine system, specifically, the hypothalamic-pituitary axis. However, no manual therapy study has investigated the neuroendocrine response to SM (ie, sympa...

The aim of this meta-analysis was to determine the effectiveness of spinal manipulation in influencing various biochemical markers in healthy and or symptomatic population. Electronic databases (n = 10) were searched (from inception till September 2016) and eight trials (325 participants) that met the inclusion criteria were included in the meta-a...

Passive heat induces beneficial perfusion profiles, provides substantive cardiovascular strain and reduces blood pressure, thereby holding potential for healthy and cardiovascular disease populations. The aim of this study was to assess acute responses to passive heat via lower-limb hot-water immersion in patients with peripheral arterial disease (...

Key points: Despite an attenuated fluctuation in ovarian hormone concentrations in well-trained women, one in two of such women believe their menstrual cycle negatively impacts training and performance. Forthcoming large international events will expose female athletes to hot environments, and studies evaluating aerobic exercise performance in suc...

Purpose: To compare energy use and substrate partitioning arising from repeated lower- versus upper-body sprints, or endurance exercise, across a 24-h period. Methods: Twelve untrained males (24±4 y) completed three trials in randomized order: (1) repeated sprints (five 30-s Wingate, 4.5-min recovery) on a cycle ergometer (SITLegs); (2) 50-min c...

Exercise-associated hyponatremia can be life-threatening. Excessive hypotonic fluid ingestion is the primary etiological factor but does not explain all variability. Possible effects of chronic sodium intake are unknown. The aim of this study was to determine whether dietary sodium affects plasma sodium concentration [Na(+) ] during exercise in the...

Introduction: Exercise reduces arterial and central venous blood pressures during recovery, which contributes to its valuable anti-hypertensive effects and to facilitating hypervolemia. Repeated sprint exercise potently improves metabolic function, but its cardiovascular effects (esp. hematological) are less well-characterized, as are effects of ex...

Purpose : To examine the retention and re-acclimation responses during a periodized heat acclimation (HA) protocol in elite sailors preparing for the 2013 World Championships in Muscat, Oman (∼27-30°C, 40-60% RH). Methods : Two elite male Laser class sailors completed 5 consecutive days of HA (60 min per day in 35°C, 60% RH). Heat response tests (...

Introduction Routine measurement of cardiac biomarkers such as troponin T (TnT) is recommended perioperatively, especially in high-risk vascular surgery. Long-term prognosis is worse even in those with nonspecific perioperative myocardial injury. However, a clear understanding of these biomarker profiles and how they should affect patient managemen...

Objectives Remote ischemic preconditioning (RIPC) involves the phenomenon whereby transient episodes of limb ischemia induced by cuff inflation provide cardioprotection. The effectiveness of RIPC in vascular surgery is uncertain. This randomized, controlled trial was designed to investigate the potential of two episodes of RIPC to provide myocardia...

Alongside age-related brain deterioration, cognitive functioning declines, particularly for more demanding tasks. Past research indicates that, to offset this decline, older adults exhibit hemodynamic changes consistent with recruitment of more anterior brain regions. However, the nature of the hemodynamic changes remains unclear. To address this k...

Exercise induces arterial flow patterns that promote functional and structural adaptations, improving functional capacity and reducing cardiovascular risk. While heat is produced by exercise, local and whole-body passive heating have recently been shown to generate favorable flow profiles and associated vascular adaptations in the upper limb. Flow...

We believe available data support the thesis that HA can improve performance in cool conditions, and perhaps with less expense and fewer side-effects than hypoxia (Dempsey & Morgan, 2015), but its utility is unresolved and may be modest or absent in some settings and individuals. A few key issues are becoming clear, however. First, HA must be of su...

Long-haul air travel imposes multiple stressors, arising from prolonged immobility, low humidity, modest hypobaria, circadian disruption and oxidative stress from food and cosmic radiation [1]. We developed a beverage system (Flyhidrate™ a) to counteract such effects, using ingredients shown in previous research to be effective when used acutely in...