Michael S Koehle

University of British Columbia | UBC · School of Kinesiology

Previous studies based on animal models have raised concerns about salbutamol use in ozone air pollution with regard to ozone related lung injury. We conducted a double‐blind, randomized, placebo‐controlled crossover study including 18 subjects diagnosed with EIB by a eucapnic voluntary hyperpnea (EVH) test. Participants completed 30 min of standar...

Background Flow limitations in the iliac arteries (FLIA) is a sport-related vascular condition increasingly recognised as an occupational risk for professional cyclists and other endurance athletes. Surgical reconstruction is the definitive treatment for athletes wishing to continue competition. However, less information has been published regardin...

Introduction Wearable near-infrared spectroscopy (NIRS) can be used during dynamic exercise to reflect the balance of muscle oxygen delivery and uptake. This study describes the behaviour and reliability of postexercise reoxygenation with NIRS as a function of exercise intensity at four muscle sites during an incremental cycling test. We discuss ph...

During pregnancy an increased cardiac output () and blood volume (BV) occur to support fetal growth. Increased and BV also occur during chronic endurance exercise training and benefit performance. We investigated if sprint interval training (SIT) undertaken early postpartum maintains the elevated and BV of pregnancy and benefits performance. The pa...

Ground-level ozone (O 3) is a potent air pollutant well recognized to acutely induce adverse 26 respiratory symptoms and impairments in pulmonary function. However, it is unclear how the 27 hyperpnea of exercise may modulate these effects, and the subsequent consequences on exercise 28 performance. We tested the hypothesis that pulmonary function a...

Ground-level ozone (O 3 ) is a potent air pollutant well recognized to acutely induce adverse respiratory symptoms and impairments in pulmonary function. However, it is unclear how the hyperpnea of exercise may modulate these effects, and the subsequent consequences on exercise performance. We tested the hypothesis that pulmonary function and exerc...

In this review, we discuss some of the recent advances in our understanding of the physiology of the air pollution and exercise. The key areas covered include the effect of exercise intensity, the effects of pre‐exposure to air pollution, acclimation to air pollution, and the utility of masks during exercise. Although higher intensity exercise lead...

The benefits of physical activity on health and well-being are well researched. Climate change, characterized by more extreme, more frequent, and longer-lasting exposures to environmental threats, however, changes the playing field. Physiological responses to physical activity might catalyze adverse effects of air pollution, extreme ambient tempera...

Introduction Wearable near-infrared spectroscopy (NIRS) measurements of muscle oxygen saturation (SmO 2 ) demonstrated good test–retest reliability at rest. We hypothesized SmO 2 measured with the Moxy monitor at the vastus lateralis (VL) would demonstrate good reliability across intensities. For relative reliability, SmO 2 will be lower than volum...

Introduction: Air pollution is a global issue known to effect on human health and performance. In the context of highly skilled athletes, the influence of air pollution on players' physical and technical abilities are established, yet its effects on cognitive performance have received little consideration. This study aims to address this research...

The purpose of the study was to characterize exercise induced arterial hypoxemia (EIAH) in female masters athletes (FMA). We hypothesized that FMA would experience EIAH during treadmill running. Eight FMA (48-57 years) completed pulmonary function testing and an incremental exercise test until exhaustion (V̇O2max=45.7±6.5, range:35-54ml/kg/min). On...

It is well established that undertaking regular vigorous physical activity is associated with a broad range of bene- fits, including for cardiac, metabolic and cognitive health. Participation in sport, however, places specific demands on the respiratory system of athletic individuals and by its very nature, necessitates heightened levels of venti-...

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Natural Sciences and Engineering Research Council of Canada and B.C. Sports & Exercise Medicine Research Foundation. Background The epidemiologic evidence suggests that the health benefits of exercise in healthy adults outweigh the adverse effects of air pollutio...

Air pollution is commonly defined as the contamination of the air we breathe by any chemical, physical or biological agent that is potentially threatening to human and ecosystem health. The common pollutants known to be disease-causing are particulate matter, ground-level ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide. Although the as...

Introduction: Exercising outdoors may inadvertently lead to individuals inhaling levels of air pollution that may be detrimental to their health and activity-related performance. Endurance athletes are a particularly susceptible subgroup due to their high ventilation rates sustained over prolonged periods of time coupled with high training loads t...

Near-infrared spectroscopy (NIRS) quantifies muscle oxygenation (SmO2) during exercise. Muscle oxygenation response to self-paced, severe-intensity cycling remains unclear. Observing SmO2 can provide cycling professionals with the ability to assess muscular response, helping optimize decision-making. We aimed to describe the effect of self-paced se...

Following high-intensity, normoxic exercise there is evidence to show that healthy females, on average, exhibit less fatigue of the diaphragm relative to males. In the present study, we combined hypoxia with exercise to test the hypothesis that males and females would develop a similar degree of diaphragm fatigue following cycle exercise at the sam...

After a bout of isolated inspiratory work, such as inspiratory pressure threshold loading (IPTL), the human diaphragm can exhibit a reversible loss in contractile function, as evidenced by a decrease in transdiaphragmatic twitch pressure (PDI,TW ). Whether or not diaphragm fatigability after IPTL is affected by neural mechanisms, measured through v...

Background:Sporting events are commonly held in environments that differ from an athlete’s typical training environment, impacting performance. To maximize performance and tolerance of said environments, athletes often employ adaptation strategies in natural or controlled-stress settings prior to competition. The purpose of this case study was to d...

Air pollution is among the leading environmental threats to health around the world today, particularly in the context of sports and exercise. With the effects of air pollution, pollution episodes (eg, wildfire conflagrations) and climate change becoming increasingly apparent to the general population, so have their impacts on sport and exercise. A...

Intense inspiratory muscle work evokes a sympathetically mediated pressor reflex, termed the respiratory muscle metaboreflex, in which young females demonstrate an attenuated response relative to males. However, the effects of ageing and female sex hormones on the respiratory muscle metaboreflex are unclear. We tested the hypothesis that the presso...

Introduction: A lack of knowledge among laypersons about the hazards of high-altitude exposure contributes to morbidity and mortality from acute mountain sickness (AMS), high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE) among high-altitude travelers. There are guidelines regarding the recognition, prevention, and treatme...

Adolescents living with type 1 diabetes (T1D) have an increased risk of developing cardiovascular disease. Sleep patterns have physiological and behavioral impacts on diabetes outcomes. This study aimed to investigate the associations between sleep patterns and CVD risk factors in adolescents living with T1D and their peers living without T1D. This...

Purpose: This study aims to investigate the relationship between split disciplines and overall extreme ultra-triathlon (EUT) performance and verify the relationship among physiological and neuromuscular measurements with both fractional and total EUT performance while checking which variables could predict partial and overall EUT race time. Methods...

Background Many individuals develop excess skin (ES) following massive weight loss (MWL). Patient reported outcomes demonstrate that abdominal ES negatively impacts perceived physical function which is improved by abdominal body contouring surgeries (ABCS). However, the effect of ABCS on objective measures of physical function is unknown. Objectiv...

The aim of the present study was to analyze the effects of traffic-related air pollution (TRAP) on markers of inflammatory, neuroplasticity, and endurance performance-related parameters in recreationally trained cyclists who were adapted to TRAP during a 50-km cycling time-trial (50-km cycling TT). Ten male cyclists performed a 50-km cycling TT ins...

The critical power (CP) concept represents the uppermost rate of steady state aerobic metabolism during work. Work above CP is limited by a fixed capacity ( W ′) with exercise intensity being an accelerant of its depletion rate. Exercise at CP is a considerable insult to homeostasis and any work done above it will rapidly become intolerable. Humans...

The relationship between the muscle deoxygenation breakpoint (Deoxy-BP) measured with near-infrared spectroscopy (NIRS), and the respiratory compensation point (RCP) has been well established. This relationship has also been reported using wearable NIRS, however not in locomotor and non-locomotor muscles simultaneously during whole-body cycling exe...

Introduction: The female diaphragm develops less fatigue following high intensity exercise compared to males. Diaphragm fatigability is typically defined as a decrease in transdiaphragmatic twitch pressure (Pdi,TW) and represents the contractile function of the muscle. However, it is unclear whether this sex difference persists when examining chan...

Background The physical environment can facilitate or hinder physical activity. A challenge in promoting physical activity is ensuring that the physical environment is supportive and that these supports are appropriately tailored to the individual or group in question. Ideally, aspects of the environment that impact physical activity would be enhan...

This prospective cohort study investigated the relationships between cumulative training loads measured in arbitrary units (AU), non-training stress levels, and athletic injury risk in one team of male collegiate ice hockey players. Measures of athlete training load and non-training stress were recorded each on-ice session over one season. Daily lo...

Background Individuals with exercise-induced bronchoconstriction (EIB) use inhaled ß2-agonists prior to exercise to prevent respiratory symptoms. The resulting bronchodilation could increase the dose of inhaled pollutants and worsen dyspnea when exercise is performed in air pollution. Objective To assess the effects of salbutamol, a ß2-agonist, an...

High-intensity interval exercise (HIIE) is an effective non-pharmacological tool for improving physiological responses related to health. When HIIE is performed in urban centers, however, the exerciser is exposed to traffic-related air pollution (TRAP), which is associated with metabolic, anti-inflammatory imbalance and cardiovascular diseases. Thi...

Background The number of adults across the globe with significant depressive symptoms has grown substantially during the COVID-19 pandemic. The extant literature supports exercise as a potent behaviour that can significantly reduce depressive symptoms in clinical and non-clinical populations. Objective Using a suite of mobile applications, at-home...

Background The acute effects of air pollution (AP) exposure during physical activity have been studied. However, comprehensive systematic reviews are lacking, particularly regarding moderate-to-vigorous physical activity (MVPA).Objective Our objective was to determine the acute health- and exercise-related effects of AP exposure during a bout of MV...

Objective: To explore the combination of measuring muscle oxygenation with near-infrared spectroscopy (NIRS) and cycling power during provocative incremental exercise for the detection of iliac arterial blood flow limitation (IAFL) in an otherwise healthy, well-trained cyclist. Design: Case report and methodological pilot study. Setting: Unive...

The efficacy of a 14-day field-based heat acclimatization (HA) training camp in 16 international female soccer players was investigated over three phases: phase 1: 8 days moderate HA (22. 1°C); phase 2: 6 days high HA (34.5°C); and phase 3: 11 days of post-HA (18.2°C), with heart rate (HR), training load, core temp (Tc), and perceptual ratings reco...

Background: The number of adults across the globe with significant depressive symptoms has grown substantially during the COVID-19 pandemic. The extant literature supports exercise as a potent behavior that can significantly reduce depressive symptoms in clinical and non-clinical populations. Objective: Using a suite of mobile applications, at-home...

Background Type 1 diabetes mellitus (T1DM) is associated with an increased risk for cardiovascular disease (CVD) related morbidity and premature mortality. Regular physical activity plays an important role in the primary and secondary prevention of CVD, improving overall health and wellbeing. Previous observational studies have examined the associa...

Blood pressure is a function of cardiac output and peripheral vascular resistance. During graded exercise testing (GXT), systolic blood pressure (SBP) is expected to increase gradually along with work rate, oxygen consumption, heart rate, and cardiac output. Individuals exposed to chronic endurance training attain a greater exercise SBP than in the...

Background: Type 1 diabetes (T1D) is associated with a high risk of cardiovascular disease (CVD) and an increased rate of premature mortality from CVD. Regular physical activity can improve overall health and wellbeing and plays an important role in primary and secondary prevention of CVD. Methods: This cross-sectional study assessed cardiovascular...

Objective Individuals with exercise-induced bronchoconstriction (EIB) use ß2-agonists to reduce respiratory symptoms during acute exercise. The resulting bronchodilation could increase the dose of inhaled pollutants and impair respiratory function when exercise is performed in air pollution. We aimed to assess respiratory responses in individuals w...

New findings: What is the central question of this study? How does sternocleidomastoid blood flow change in response to increasing ventilation and whole-body exercise intensity? What is the main finding and its importance? Sternocleidomastoid blood flow increased with increasing ventilation. For a given ventilation, sternocleidomastoid blood flow...

Objectives Significant resources are invested in maximizing player performance without extensive knowledge of the athletic progression of elite female soccer players during their career. The aim of the current study was therefore to investigate the change in physical performance characteristics in 12- to 34-year-old female soccer players in a natio...

Purpose: To examine the association between day-to-day resting cardiac parasympathetic variability over consecutive non-training days (i.e. weekend) and accumulated exercise stress when quantified using indices of cardiovascular strain. Methods: Twelve international calibre female field hockey players training as part of a national team were partic...

Voluntary activation can be used to assess central fatigue of the diaphragm after tasks such as exercise or inspiratory muscle loading. Cervical magnetic stimulation (CMS) of the phrenic nerves elicits an involuntary contraction, or twitch, of the diaphragm. This twitch is quantified based on a measure of transdiaphragmatic pressure and can be used...

PURPOSE: Air pollution is one of the main health risks caused by the environment. Exposure to particulate matter smaller than 2.5 microns in diameter (PM2.5) leads to an increase in risk for cardiovascular and respiratory disease. Although many major sporting events are held in large, polluted cities (e.g. the Beijing 2008 and Rio 2016 Olympic Game...

Key points Diaphragm fatigue may increase the intensity (sensory dimension) and unpleasantness (affective dimension) of dyspnoea, which may partially explain why diaphragm fatigue negatively affects exercise performance. We hypothesized that diaphragm fatigue would negatively affect exercise performance via increases in both the intensity and unple...

Swimmers have a high prevalence of exercise induced bronchoconstriction (EIB), which may be associated with repeated exposure to chlorinated pool water. The eucapnic voluntary hyperpnea (EVH) test is used to diagnose EIB; however, it fails to replicate the environmental conditions experienced by swimmers. The relationship between the composition of...

In endurance sports, adjusting exercise intensity and pacing to delay muscle fatigue is a crucial strategy to optimize performance. The purpose of this study was to examine a measure of muscle fatigue based on near-infrared spectroscopy (NIRS) monitoring of muscle oxygenation dynamics during exercise. Eleven trained male cyclists performed a Functi...

Background: The combined effects of physical activity and air pollution exposure on vascular function are insufficiently understood, particularly after the inhalation of a β2-agonist, a vasodilating agent. Objective: To assess the micro- and macrovascular response to physical activity after β2-agonist use while breathing diesel exhaust (DE) in i...

The aim of this study was to develop predictive equations for minute ventilation based on heart rate, and to test the precision of the equations in two forms of endurance exercise. Eighteen men (age 27.8 ± 5.4 years old, maximal oxygen uptake 45.4 ± 8.3 ml·kg⁻¹·min⁻¹) performed a maximal progressive cycle test in which minute ventilation and heart...

The Graded Symptom Checklist (GSC), Standardized Assessment of Concussion (SAC), Balance Error Scoring System (BESS), and King-Devick Test (KDT) are considered important components of concussion assessment. Whether baseline testing improves the diagnostic utility of these tests remains unclear. We performed an observational cohort study to investig...

Training and competing in elite triathlon events challenge the limits of human performance. While it is generally felt that the respiratory system does not limit performance, several conditions exist during heavy physical work that may influence success. Exercise-induced arterial hypoxemia and expiratory flow limitation can occur in healthy athlete...

Background Exposure to particulate matter 2.5 μm or less (PM 2.5 ) that contains transition metals may play a role in systemic oxidative stress and inflammation. Exposure to diesel exhaust (DE) can increase adhesion molecules, which are important in the inflammatory response; however, it is unclear how exercising in DE affects adhesion molecules an...

Background: Perfusion of intrapulmonary arteriovenous anastomoses (IPAVA) is increased during exercise and in hypoxia and is associated with variations in oxygen saturation (SPO2), resulting in blood bypassing the pulmonary microcirculation. Sildenafil is a pulmonary vasodilator that improves SPO2 and endurance performance in hypoxia. The purpose o...

This study examined the congruence between the prescribed and experienced heart rate derived training loads over a five week periodized mesocycle. Twenty-four elite female field hockey players training as part of a national team were monitored prior to an (FIH) Hockey World League tournament. Three on-field training sessions per week were prospecti...

Underwater sports and exercise medicine

Objective Sildenafil is a pulmonary vasodilator that may reduce the decrement in endurance performance in moderate hypoxia. We assessed the efficacy of sildenafil to improve performance in hypoxia. Data sources/eligibility Criteria We systematically searched electronic databases (until August 2018) for randomised trials comparing sildenafil with p...

Purpose: The physiological consequences of freely chosen cadence (FCC) during cycling remains poorly understood. We sought to determine the effect of cadence on the respiratory and hemodynamic response to cycling exercise. Methods: Eleven cyclists (10M:1F; age=27±6yr; V[Combining Dot Above]O2max=60.8±3.7ml·kg·min) completed four, 6-min constant-...

Sildenafil is a pulmonary vasodilator that has potential to mitigate the decrement in endurance performance caused by hypoxic pulmonary vasoconstriction. The purpose of this study was to determine the effects of sildenafil on pulmonary artery pressure, cardiac output, pulse oxygen saturation, and exercise performance at moderate simulated altitude....

A complete dataset from this experiment can be found in the supplementary information. (XLSX)

Road criterium and track bicycle racing occur at high speeds, demand repeated high power outputs, last 10–90 min, and offer little chance for recovery after the event. Consecutive evenings of criterium and track racing are respectively known as speed-week or six-day events and take place in evening hours over the course of a week. Given the schedul...