Luisa V. Giles

The Physiology of Rock Climbing

In general, elite climbers have been characterised as small in stature, with low percentage body fat and body mass. Currently, there are mixed conclusions surrounding body mass and composition, potentially because of variable subject ability, method of assessment and calculation. Muscular strength and endurance in rock climbers have been primarily measured on the forearm, hand and fingers via dynamometry. When absolute hand strength was assessed, there was little difference between climbers and the general population. When expressed in relation to body mass, elite-level climbers scored significantly higher, highlighting the potential importance of low body mass.Rock climbing is characterised by repeated bouts of isometric contractions. Hand grip endurance has been measured by both repeated isometric contractions and sustained contractions, at a percentage of maximum voluntary contraction. Exercise times to fatigue during repeated isometric contractions have been found to be significantly better in climbers when compared with sedentary individuals. However, during sustained contractions until exhaustion, climbers did not differ from the normal population, emphasising the importance of the ability to perform repeated isometric forearm contractions without fatigue becoming detrimental to performance.A decrease in handgrip strength and endurance has been related to an increase in blood lactate, with lactate levels increasing with the angle of climbing. Active recovery has been shown to provide a better rate of recovery and allows the body to return to its pre-exercised state quicker. It could be suggested that an increased ability to tolerate and remove lactic acid during climbing may be beneficial.Because of increased demand placed upon the upper body during climbing of increased difficulty, possessing greater strength and endurance in the arms and shoulders could be advantageous.Flexibility has not been identified as a necessary determinant of climbing success, although climbing-specific flexibility could be valuable to climbing performance.As the difficulty of climbing increases, so does oxygen uptake (V̇O2), energy expenditure and heart rate per metre of climb, with a disproportionate rise in heart rate compared with V̇O2. It was suggested that these may be due to a metaboreflex causing a sympathetically mediated pressor response. In addition, climbers had an attenuated blood pressure response to isometric handgrip exercises when compared with non-climbers, potentially because of reduced metabolite build-up causing less stimulation of the muscle metaboreflex.Training has been emphasised as an important component in climbing success, although there is little literature reviewing the influence of specific training components upon climbing performance.In summary, it appears that success in climbing is not related to individual physiological variables but is the result of a complex interaction of physiological and psychological factors.

From good intentions to proven interventions: effectiveness of actions to reduce the health impacts of air pollution.

Background Associations between air pollution and a multitude of health effects are now well established. Given ubiquitous exposure to some level of air pollution, the attributable health burden can be high, particularly for susceptible populations. Objectives An international multidisciplinary workshop was convened to discuss evidence of the effectiveness of actions to reduce health impacts of air pollution at both the community and individual level. The overall aim was to summarize current knowledge regarding air pollution exposure and health impacts leading to public health recommendations. Discussion During the workshop, experts reviewed the biological mechanisms of action of air pollution in the initiation and progression of disease, as well as the state of the science regarding community and individual-level interventions. The workshop highlighted strategies to reduce individual baseline risk of conditions associated with increased susceptibility to the effects of air pollution and the need to better understand the role of exposure duration in disease progression, reversal, and adaptation. Conclusion We have identified two promising and largely unexplored strategies to address and mitigate air pollution–related health impacts: reducing individual baseline risk of cardiovascular disease and incorporating air pollution–related health impacts into land-use decisions.

The Health Effects of Exercising in Air Pollution

The health benefits of exercise are well known. Many of the most accessible forms of exercise, such as walking, cycling, and running often occur outdoors. This means that exercising outdoors may increase exposure to urban air pollution. Regular exercise plays a key role in improving some of the physiologic mechanisms and health outcomes that air pollution exposure may exacerbate. This problem presents an interesting challenge of balancing the beneficial effects of exercise along with the detrimental effects of air pollution upon health. This article summarizes the pulmonary, cardiovascular, cognitive, and systemic health effects of exposure to particulate matter, ozone, and carbon monoxide during exercise. It also summarizes how air pollution exposure affects maximal oxygen consumption and exercise performance. This article highlights ways in which exercisers could mitigate the adverse health effects of air pollution exposure during exercise and draws attention to the potential importance of land use planning in selecting exercise facilities.

The effect of pre-exercise diesel exhaust exposure on cycling performance and cardio-respiratory variables.

Purpose: To determine the effect of pre-exercise exposure to diesel exhaust (DE) on 20-km cycling performance, pulmonary function, and cardio-respiratory variables during exercise. Methods: Eight endurance-trained males participated in the study. Test days consisted of a 60-min exposure to either filtered air (FA) or DE, followed by a 20 km cycling time trial. Exposures to DE were at a concentration of 300 µg/m3 of PM2.5. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were measured before and after exposure, and after exercise. Oxygen consumption (VO2) and carbon dioxide production (VCO2), minute ventilation (VE), tidal volume (VT), breathing frequency (FB), heart rate and oxyhemoglobin saturation (SpO2), were collected during the time trials. The effect of condition on time trial duration, an order effect, and mean cardio-respiratory variables were each analysed using paired T-tests. Repeated-measures ANOVA were used to assess the effect of DE exposure on pulmonary function. Results: There was a main effect of condition (FA vs. DE) on the change in FEV1 from baseline, and in exercise heart rate. Post hoc tests revealed that exercise-induced bronchodilation was significantly attenuated following DE compared to FA. There were no main effects of condition on 20 km cycling performance, or VO2, VCO2, VE, VT, FB and SpO2 during a 20 km time trial. Conclusion: A 60-min exposure to DE prior to exercise significantly attenuated exercise-induced bronchodilation and significantly increased heart rate during exercise. Pre-exercise exposure to diesel exhaust did not significantly impair 20 km cycling time trial performance.

Physiological Responses to Diesel Exhaust Exposure Are Modified by Cycling Intensity

BACKGROUND Outdoor exercisers are frequently exposed to diesel exhaust (DE) that contains particulate matter (PM) air pollution. How the respiratory and metabolic responses to exercise are affected by DE exposure and how these responses change with exercise intensity are unknown. PURPOSE This study aimed to determine the respiratory and metabolic responses to low- and high-intensity cycling with DE exposure containing high levels of PM. METHODS Eighteen males age 24.5 ± 6.2 yr performed 30-min trials of low-intensity (30% of power at V˙O2peak) and high-intensity (60% of power at V˙O2peak) cycling as well as rest. Each trial was performed once while breathing filtered air (FA) and once while breathing DE (300 μg·m of PM2.5) for a total of six trials, each separated by 7 d. During the trials, minute ventilation (V˙E), oxygen consumption (V˙O2), CO2 production (V˙CO2), RER, and perceived exertion for lungs (RPELungs) and legs (RPELegs) were measured. Work of breathing, respiratory muscle V˙O2, ratio of O2 consumption to power output, and gross efficiency were estimated. RESULTS The RER was significantly lower (0.02 lower, P = 0.008), and the RPELungs (0.9 greater, P = 0.001) and the RPELegs (0.6 greater, P = 0.017) were significantly greater, in DE compared with FA. During low-intensity exercise, V˙E (44.5 ± 8.9 vs 40.5 ± 8.0 L·min, P < 0.001), V˙O2 (27.9 ± 5.4 vs 24.9 ± 4.4 mL·kg·min, P = 0.001), and V˙CO2 (25.9 ± 5.3 vs 23.5 ± 4.5 mL·kg·min, P = 0.006) were significantly greater in DE. This pattern was not seen during high-intensity cycling. CONCLUSIONS Respiratory and metabolic responses to low-intensity, but not high-intensity, cycling in DE exceed FA. Practically, the greater responses during low-intensity exercise in DE could have implications for individuals with cardiopulmonary disease. Also, the elevated RPE during DE could impair performance in self-paced exercise.

The effects of exercise in hypoxic and normoxic conditions on endothelin-1 and arterial compliance

Abstract The purpose of this study was to determine the effects of short-term normoxic and hypoxic exercise on plasma endothelin-1 and nitric oxide levels, and the relationship of arterial compliance and pulmonary artery pressure to endothelin-1. Seven endurance-trained males completed two incremental and two steady-state exercise tests performed at ventilatory threshold in normoxia and hypoxia (fraction of inspired oxygen = 0.14). Plasma endothelin-1was measured throughout steady-state tests. Arterial compliance using applanation tonometry, plasma nitric oxide and pulmonary artery pressure using Doppler echocardiography were measured before and after exercise. Small arterial compliance and pulmonary artery pressure significantly increased following exercise. There were no main effects of condition or time for plasma endothelin-1and nitric oxide levels. There were no significant relationships between plasma endothelin-1 and arterial compliance or pulmonary artery pressure. In conclusion, mechanisms other than the endothelial system may play a role in the exercise-induced changes in small artery compliance in this study population. Moderate hypoxia and a 30-minute steady-state exercise have limited effects on plasma endothelin-1 in endurance-trained males.

The effect of low and high-intensity cycling in diesel exhaust on flow-mediated dilation, circulating NOx, endothelin-1 and blood pressure

Introduction Exposure to air pollution impairs aspects of endothelial function such as flow-mediated dilation (FMD). Outdoor exercisers are frequently exposed to air pollution, but how exercising in air pollution affects endothelial function and how these effects are modified by exercise intensity are poorly understood. Objectives Therefore, the purpose of this study was to determine the effects of low-intensity and high-intensity cycling with diesel exhaust (DE) exposure on FMD, blood pressure, plasma nitrite and nitrate (NOx) and endothelin-1. Methods Eighteen males performed 30-minute trials of low or high-intensity cycling (30% and 60% of power at VO2peak) or a resting control condition. For each subject, each trial was performed once while breathing filtered air (FA) and once while breathing DE (300ug/m3 of PM2.5, six trials in total). Preceding exposure, immediately post-exposure, 1 hour and 2 hours post-exposure, FMD, blood pressure and plasma endothelin-1 and NOx concentrations were measured. Data were analyzed using repeated-measures ANOVA and linear mixed model. Results Following exercise in DE, plasma NOx significantly increased and was significantly greater than FA (p<0.05). Two hours following DE exposure, endothelin-1 was significantly less than FA (p = 0.037) but exercise intensity did not modify this response. DE exposure did not affect FMD or blood pressure. Conclusion Our results suggest that exercising in DE did not adversely affect plasma NOX, endothelin-1, FMD and blood pressure. Therefore, recommendations for healthy individuals to moderate or avoid exercise during bouts of high pollution appear to have no acute protective effect.