Healthcare professional’s guide to cardiopulmonary exercise testing

Cardiopulmonary exercise testing (CPEX) is a valuable clinical tool that has proven indications within the fields of cardiovascular, respiratory and pre-operative medical care. Validated uses include investigation of the underlying mechanism in patients with breathlessness, monitoring functional status in patients with known cardiovascular disease and pre-operative functional state assessment. An understanding of the underlying physiology of exercise, and the perturbations associated with pathological states, is essential for healthcare professionals to provide optimal patient care. Healthcare professionals may find performing CPEX to be daunting, yet this is often due to a lack of local expertise and guidance with testing. We outline the indications for CPEX within the clinical setting, present a typical protocol that is easy to implement, explain the key underlying physiological changes assessed by CPEX, and review the evidence behind its use in routine clinical practice. There is mounting evidence for the use of CPEX clinically, and an ever-growing utilisation of the test within research fields; a sound knowledge of CPEX is essential for healthcare professionals involved in routine patient care

Breakpoints in ventilation, cerebral and muscle oxygenation, and muscle activity during an incremental cycling exercise.

The aim of this study was to locate the breakpoints of cerebral and muscle oxygenation and muscle electrical activity during a ramp exercise in reference to the first and second ventilatory thresholds. Twenty-five cyclists completed a maximal ramp test on an electromagnetically braked cycle-ergometer with a rate of increment of 25 W/min. Expired gazes (breath-by-breath), prefrontal cortex and vastus lateralis (VL) oxygenation [Near-infrared spectroscopy (NIRS)] together with electromyographic (EMG) Root Mean Square (RMS) activity for the VL, rectus femoris (RF), and biceps femoris (BF) muscles were continuously assessed. There was a non-linear increase in both cerebral deoxyhemoglobin (at 56 ± 13% of the exercise) and oxyhemoglobin (56 ± 8% of exercise) concomitantly to the first ventilatory threshold (57 ± 6% of exercise, p > 0.86, Cohen's d < 0.1). Cerebral deoxyhemoglobin further increased (87 ± 10% of exercise) while oxyhemoglobin reached a plateau/decreased (86 ± 8% of exercise) after the second ventilatory threshold (81 ± 6% of exercise, p < 0.05, d > 0.8). We identified one threshold only for muscle parameters with a non-linear decrease in muscle oxyhemoglobin (78 ± 9% of exercise), attenuation in muscle deoxyhemoglobin (80 ± 8% of exercise), and increase in EMG activity of VL (89 ± 5% of exercise), RF (82 ± 14% of exercise), and BF (85 ± 9% of exercise). The thresholds in BF and VL EMG activity occurred after the second ventilatory threshold (p < 0.05, d > 0.6). Our results suggest that the metabolic and ventilatory events characterizing this latter cardiopulmonary threshold may affect both cerebral and muscle oxygenation levels, and in turn, muscle recruitment responses

Ventilatory Mechanics in Endurance Athletes

The lungs were once thought to be over-built for exercise. However, upon further research, endurance athletes have been found to reach their maximum ventilation, demonstrating an insufficiency of the lungs to accommodate the demands of highly demanding endurance sport. This knowledge has inspired researchers to look further into the exercise ventilatory responses and, in doing so, researchers discovered that the adaptations of the pulmonary system to endurance training are still not well understood. Potential reasons for this lack of knowledge may be methodological measurement limitations, as ventilatory mechanics have been measured classically either invasively or by breathing maneuvers. These measurements are difficult to perform during high intensity exercise and in large groups of athletes. However, recent innovations in motion analysis technology have allowed for ventilatory mechanics to be measured during high intensity exercise, potentially allowing for further insight into how high intensity endurance training impacts ventilatory mechanics. The purpose of this study is to describe normal ventilatory mechanics during exercise in endurance trained and healthy untrained individuals, explore potential gender differences during exercise and investigate the impact of flow limitation during exercise on ventilatory mechanics, using a motion analysis system that allows researchers to obtain information on chest wall volume changes and chest wall compartmental interactions during high intensity exercise. This motion analysis system is called Optoelectronic Plethysmography (OEP). This dissertation is comprised of an introduction to the work and the 3 projects that comprise the dissertation along with an appendix, which includes a complete literature review. The three projects are as follows (1) an introduction to motion analysis as a tool in measuring ventilatory mechanics, (2) research determining the differences in the ventilatory mechanics in endurance athletes and healthy controls from rest to maximal exercise and (3) the differences in ventilatory mechanics between endurance trained women who demonstrate expiratory flow limitation during high intensity exercise versus endurance trained women who do not. Project 1: Optoelectronic Plethysmography (OEP) is a motion analysis tool that can be used to define exercise ventilatory mechanics by analyzing chest wall movements and calculating volume changes. By analyzing breathing mechanics by motion analysis rather than traditional breathing maneuvers, individual components of the chest wall can be analyzed and changes in volume throughout the chest wall can be assessed without altering the individual's natural breathing pattern. This review presents the history and development of OEP technology, along with a summary of the methods used and a discussion of findings to date, giving insight into exercise ventilatory mechanics never investigated before. Project 2: Differences between the ventilatory mechanics of endurance athletes and non athletes using motion analysis have not yet been described. To determine how increased ventilatory demand impacts ventilatory kinematics, we compared the total chest wall volume variations (VCW) of 18 male and female endurance-trained athletes (ET) to 14 untrained individuals (UT) during exercise. We hypothesized that training and gender would have an effect on VCW and kinematics at maximal exercise. Gender and training significantly influenced chest wall kinematics. Female ET did not change chest wall end-expiratory volume (VCW,ee) or pulmonary ribcage end-expiratory volume (VRCp,ee) with exercise, while female UT significantly decreased VCW,ee and VRCp,ee with exercise (p<0.05). Female ET significantly increased pulmonary ribcage end-inspiratory volume (VRCp,ei) with exercise (p<0.05), while female UT did not change VRCp,ei with exercise. Male ET significantly increased VRCp,ei with exercise (p<0.05); male UT did not. Men and women had significantly different VCW (p <0.05). Women demonstrated the greatest variation of VCW in the pulmonary ribcage compartment (VRCp). Men had similar volumes in the VRCp and the abdomen (VAb). In conclusion, gender and training had a significant association with ventilatory kinematics. Project 3: Research has found potential limitations of the airways to accommodate the large tidal volumes generated during high intensity exercise. This airway limitation has been defined as expiratory flow limitation (EFL) observed during high intensity exercise in a large percentage of healthy women. Because of endurance athletes' ability to exercise at high intensities for prolonged periods of time and produce greater than average tidal volumes, female endurance athletes may be particularly susceptible to EFL and the impact EFL may have on performance. The purpose of this last chapter was to investigate the ventilatory mechanics and exercise capacity parameters of female endurance athletes with and without EFL. Female competitive cyclists participated in two days of testing; day one consisted of a maximal aerobic capacity test (V ̇o2max test) with spirometry and day two involved chest wall motion analysis testing during two steady state exercise tests. Baseline flow volume loops were performed prior to exercise and repeated post exercise. During exercise participants performed flow volume loops at minutes 4, 6, 8 and last 30 seconds of exercise. EFL was considered present when the exercise flow volume loop surpassed the baseline flow volume loop. To quantify the degree of flow limitation when comparing the peak exercise flow volume loop to the baseline flow volume loop, we calculated the percent flow volume loop reserve (%FVL reserve). Two levels of submaximal constant-load exercise bouts (at 60% and 85% maximal watts) were employed to investigate if EEFL impacted ventilatory mechanics differently at different intensities. Optoelectronic plethysmography (OEP) was employed to measure VT from the pulmonary ribcage (VRCp), abdominal ribcage (VRCa) and the abdomen (VAb), as well as to measure end-expiratory volume chest wall volume (EEEV) to calculate potential dynamic hyperinflation. Comparison of participants with and without EFL was made using an ANOVA or Kruskal-Wallis test (p≤0.05). Predictors of %FVL reserve were explored with a multiple linear regression. Two participants were not included in the data analysis due to the presence of asthma (one at rest, one exercise induced) as determined by spirometry during day one testing. Out of the other 28 participants, 6 participants had definite EFL (DEFL) demonstrated by overlapping of the peak exercise flow volume loop with the pre and post exercise flow volume loop, 5 had borderline EFL (BEFL) demonstrated by an overlapping of only the pre exercise flow volume loop and 17 had no EFL (NEFL) demonstrated by no overlapping of the pre or post flow volume loops. All participants had within normal limits of the percent predicted normal reference values in resting forced expiratory volume in 1 second (FEV1), forced mid expiratory flow rates (FEF25-75L/sec), forced vital capacity (FVC) and FEV1/FVC ratio. DEFL and BEFL participants' had a significantly lower FEV1/FVC ratio compared to NEFL (p=0.003), DEFL had significantly lower FEF25-75% predicted normal reference values before and after exercise compared to NEFL (p=0.004). There were no differences in the exercise capacity values between groups. During the day two steady state tests, there was a significant interaction effect between groups and exercise intensity in the %VRCa (p=0.045) and % VAb (p=0.049). End-tidal carbon dioxide pressure, FEF25-75%, history of self reported excessive mucus with exercise and % VRCp during the 85% constant load test explained 71.6% of the variability in %FVL reserve in our regression model (p=0.002). Independent predictors of %FVL reserve were: end-tidal carbon dioxide pressure (p=0.033), FEF25-75% (p=0.010) and history of excessive mucus with exercise (0.014). In conclusion, female endurance athletes demonstrating EFL had normal but significantly different FeV1/FVC ratio and significantly different abdominal ribcage and abdomen percent contribution with increased exercise intensity, but similar exercise capacities compared to the female endurance athletes with no EFL. Also, independent predictors of %FVL reserve were found to be FEF25-75%, history of mucus production with exercise and end-tidal carbon dioxide level at peak exercise. This dissertation has provided further insight into the ventilatory mechanics of endurance athletes and how potential airway limitation can impact high intensity exercise. Further research can seek to better understand if the differences in ventilatory mechanics between endurance athletes with EFL and no EFL allow for preservation of exercise capacity in the presence of airway limitatio

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 159

This bibliography lists 257 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1976

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 125

This special bibliography lists 323 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1974

Work of breathing in exercise and disease

This thesis is focussed on developing new methods and outcomes to assess respiratory function that require little or no volitional effort on behalf of the participants being tested. Specifically to attempt to detach the behaviour of the patient from the accuracy of the test of respiratory function, resulting in techniques that are simpler and easier to administer and undertake for both assessor and participant. It aims to develop methods that reduce the involvement of the participant during assessment of respiratory function. The human body’s way of controlling respiration has evolved into a sophisticated system that optimises breathing pattern to maintain the most efficient homeostatic action of the respiratory system. Eliciting and assessing this automatic response is the key to removing the action of participation from respiratory functiontesting. The focus must therefore be on developing non-invasive, sub-maximal techniques that allow participants to enter into a steady state of respiration and how this can be assessed. Two techniques were investigated; Respiratory Endurance (as the inspiratory work of breathing) and Tidal Breathing Flow Profile, and these were successfully applied in 99 adult participants (68 healthy controls and 31 COPD patients) and 75 children (48 clinical group and 27 healthy controls) who completed 467 respiratory endurance trials whilst seated and exercising, and 249 relaxed tidal breathing trials. The difficulties with lung function assessment are well established and have been described in this thesis. Much recent emphasis has been put on developing existing devices and protocols rather than developing new techniques and approaching these difficulties from alternative viewpoints. This thesis has described the development of innovative techniques to assess the function of the respiratory systems that aim to overcome the issues associated with maximal testing. It was shown that these techniques are easy to undertake for a range of participants, simple to analyse and are able to reliably differentiate between health and disease, suggesting that they could become a useful adjunct to existing methods of respiratory assessment

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 184

This bibliography lists 139 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1978

Functional electrical stimulation (FES) leg cycling exercise in paraplegia: a pilot study for the definition and assessment of exercise testing protocols and efficacy of exercise

A custom FES-cycling ergometer equipped with an electric motor and an integrated feedback system for accurate control of exercise workrate and cadence has been employed in this study. This experimental setup allowed the imposition of arbitrary workrate profiles with high precision and provided the potential for highly-sensitive exercise testing. One aim of the work described in this thesis was to propose and evaluate novel protocols for incremental exercise test (IET) and step exercise test (SET). Valid protocols would allow reliable estimation of the key markers of cardiopulmonary fitness in SCI subjects performing FES-cycling. Measures which can be used to evaluate the effect on cycling performance of changes in stimulation parameters, and which might therefore be used to optimise them, were also investigated. Thus, a second aim of this work was to determine whether oxygen uptake and a new measure of stimulation cost (i.e. the total rate of stimulation charge applied to the stimulated muscle groups during cycling) are sensitive enough to allow discrimination between the efficacy of different activation patterns during constant-power cycling. A discussion on the concept of metabolic efficiency in AB and SCI subjects is presented in this thesis. Efficiency of FES-cycling is much lower than that of voluntary cycling. Therefore, a third aim of this work was to define new efficiency measurements that are more appropriate for the SCI population. Two volunteer subjects took part in this study and the data obtained from the tests they performed are presented as case studies. The main outcome shows feasibility of the two exercise testing protocols. Moreover, the first report of a ventilatory threshold in SCI subjects during FES-cycling has been provided here. Oxygen uptake and stimulation cost measurements both allow discrimination between the efficacy of different muscle activation patterns. However, stimulation cost is more easily determined in real time, and responds more rapidly and with greatly improved signal-to-noise properties than oxygen uptake