Standardized submaximal exercise testing in never smokers: a normative study

In a population survey on the south‐western coast of Norway, 373 never smokers aged 18–73 years (230 women) without respiratory symptoms performed a standardized, progressive, incremental submaximal bicycle exercise test. All individuals were able to do an exercise involving oxygen uptake of 1·0 l min^–1, 80% of the subjects reached 1·5 l min^–1 and 50% of the subjects reached 2·0 l min^–1. The respiratory frequency (RF), ventilation (VE) and heart rate (HR) for a given oxygen uptake were all higher in women than in men. Significant predictors of failure to reach oxygen uptake of 1·5 and 2·0 l min^–1 were sex, age, body height and weight. Prediction equations are given for respiratory frequency, heart rate and ventilation for an oxygen uptake of 1·0 l min^–1 in women and 1·5 l min^–1 in men; and body height is a strong predictor for all dependent variables. A multiple linear regression analysis in women showed that age was a significant predictor of respiratory frequency (P<0·05), ventilation (P<0·001) and heart rate (P<0·001), while in men age was a significant predictor only of ventilation (P<0·001) during the bicycle exercise protocol.     

冠状动脉临界病变患者心肺运动试验的特点及临床意义

目的 回顾性分析冠状动脉临界病变患者心肺运动试验的临床特点和功能能力的变化。方法 回顾分析北京博爱医院2015年1月至2020年1月行冠状动脉造影并同期行心肺运动试验测试的患者,其中冠脉临界病变组184例,非冠心病组73例。比较两组症状、基线资料、实验室和超声心动图数据、心肺运动试验结果,并观察1年内主要心血管事件。结果 与非冠心病组相比,冠脉临界病变组男性比例显著升高(χ2=15.857, P <0.001),有吸烟史(χ2=9.067, P=0.003)、高血压病史(χ2=15.087, P <0.001)、高脂血症病史(χ2=13.507, P <0.001)的比例明显升高;糖化血红蛋白(Z=2.431, P=0.015)和超敏C-反应蛋白(Z=2.108, P=0.035)水平偏高;达到无氧阈比例明显偏低(χ2=10.702, P=0.001);无氧阈时的心率和呼吸交换率降低(Z> 2.156, P <0.05);两组1年后主要心血管事件发生率无显著性差异(P=1.000)。结论 冠脉临界病变患者心肺功能有所降低,应控制吸烟、高血压、高脂血症、糖尿...     

Relationship Between Heart Rate and Minute Ventilation, Tidal Volume and Respiratory Rate During Brief and Low Level Exercise

The correlation between heart rate (HR) and three respiratory parameters, minute ventilation (VE), tidal volume (Vt), and respiratory rate (RR), were studied. Four healthy subjects performed four exercise tests duration 30 seconds at 50, 100, 150, or 200 W), in random order. Cardio-respiratory parameters were recorded respiratory cycle by respiratory cycle. The results of these low level exercise tests showed that oxygen consumption (VO₂) was strongly correlated with VE (r = 0.91 ± 0.10; P < 0.01) (except in one test) and Vt (r =0.91 ± 0.07; P < 0.001) (except in one test). There was no significant correlation between VO² and RR. At exercise onset HR, VE, and Vt were modified in a matter of a few heart beats while RR varied depending on the subject and the level of exercise. During exercise average HR, VE, and Vt were significantly higher than at rest in most cases; but RR was not significantly changed by exercise. The correlations between HR and VE, Vt and RR varied from one individual to another. Nevertheless, the correlation coefficients were positive for VE and Vt, while they were negative for RR. Sensing respiratory rate thus appears to be insufficient for responsive pacing of exercise onset, but sensing respiratory volumes (Vt, VE) should give satisfactory results.     

Changes in cardiac autonomic regulation after prolonged maximal exercise

Harmful cardiac events occurs frequently after exercise. However, the cardiac autonomic regulation after vigorous exercise is not well known. This study was designed to assess heart rate (HR) variability before and after a 75 km cross‐country skiing race. HR variability was assessed by using standard statistical measures along with spectral and quantitative Poincarè plot analysis of HR variability in 10 healthy male subjects (age 36 ± 11 years). The average HR was at the same level 1 day after the race as before the race, but on the second day, HR was significantly lower (P<0·001) compared with the prerace and 1 day after values. The normalized high‐frequency (HF) spectral component of HR variability (nuHF) was lower (P<0·01) on the first day after the maximal exercise compared with the pre‐exercise values but returned to or even exceeded the prerace level on the second day (P<0·01). The changes in short‐term R‐R interval variability analysed from the Poincaré plot were similar to those observed in the HF spectral component. The normalized low‐frequency (LF) spectral component of HR variability (nuLF) was higher (P<0·01) on the first day after the exercise compared with the prerace levels and it also returned to the pre‐exercise level or even dropped below it on the second day after the race. The mean time it took the HF spectral component to return to the pre‐exercise level was 4·2 ± 4·2 h (ranging from 0 to 12 h). This recovery time correlated inversely with the maximal oxygen consumption (VO_2max) measured during the bicycle exercise test before the skiing race (r=?0·712, P<0·016). The cardiac vagal outflow is blunted for several hours after prolonged vigorous exercise. The recovery time of reduced vagal outflow depends on individual cardiorespiratory fitness and there is an accentuated rebound of altered autonomic regulation on the second day after prolonged exercise.     

Reference values for cardiopulmonary exercise testing in healthy adults: a systematic review

Reference values (RV) for cardiopulmonary exercise testing (CPET) provide the comparative basis for answering important questions concerning the normality of exercise response in patients and significantly impacts the clinical decision-making process. The aim of this study is to systematically review the literature on RV for CPET in healthy adults. A secondary aim is to make appropriate recommendations for the practical use of RV for CPET. Systematic searches of MEDLINE, EMBASE and PEDro databases up to March 2014 were performed. In the last 30 years, 35 studies with CPET RV were published. There is no single set of ideal RV; characteristics of each population are too diverse to pool the data in a single equation. Therefore, each exercise laboratory must select appropriate sets of RV that best reflect the characteristics of the population/patient tested, and equipment and methodology utilized.     

Blood metabolite data in response to maximal exercise in healthy subjects

Maximal exercise test with gas exchange measurement evaluates exercise capacities with maximal oxygen uptake (VO(2) max) measurement. Measurements of lactate (L), lactate/pyruvate ratio (L/P) and ammonium (A) during rest, exercise and recovery enhance interpretative power of maximal exercise by incorporating muscular metabolism exploration. Maximal exercise test with gas exchange measurement is standardized in cardiopulmonary evaluations but, no reference data of blood muscular metabolites are available to evaluate the muscular metabolism. We determined normal values of L, L/P and A during a standardized maximal exercise and recovery in 48 healthy sedentary volunteers and compared with results obtained in four patients with exercise intolerance and a mitochondrial disease. In healthy subjects, L, L/P and A rose during exercise. In 98% of them L, L/P or A decreased between the fifth and the fifteenth minutes of recovery. In mitochondrial patients, VO(2) max was normal or low, and L, L/P and A had the same evolution as normal subjects or showed no decrease during recovery. We gave normal L, L/P and A values, which establish references for a maximal exercise test with muscular metabolism exploration. This test is helpful for clinicians in functional evaluation, management and treatment of metabolic myopathy and would be a useful tool in diagnosis of metabolic myopathy.     

Safety and feasibility of cardiopulmonary exercise testing in head and neck cancer survivors

Purpose

Assess safety and feasibility of the cardiopulmonary exercise test (CPET) for evaluating head and neck cancer (HaNC) survivors. Also compare their cardiorespiratory fitness to age and sex-matched norms and establish current physical activity levels.

Methods

Fifty HaNC survivors [29 male; mean (SD) age, 62 (8) years], who had completed treatment up to 1 year previously, were recruited. Participants performed a CPET on a cycle ergometer to symptom-limited tolerance. Participants completed a questionnaire to report contributory factors they perceived as influencing test termination. Physical activity levels were determined using a self-reported physical activity questionnaire.

Results

Three participants did not complete the CPET because (1) poor fitting mouthpiece and naso-oral mask due to facial disfiguration from surgery; (2) knee pain elicited by cycling; and (3) early CPET termination due to electrocardiogram artefacts. Participants reached a mean peak oxygen uptake that was 34% lower than predicted and the mean (SD) CPET duration of 7:52 (2:29) min:s was significantly lower than the target test duration of 10 min (p < 0.001). Leg muscle aches and/or breathing discomfort were major contributory factors influencing test termination for 78% of participants, compared to 13% for dry mouth/throat and/or drainage in the mouth/throat. No major adverse events occurred. Participants were categorised as 26% active, 8% moderately active, and 66% insufficiently active.

Conclusion

These preliminary data suggest the CPET appears safe and feasible for most HaNC survivors when strict exclusion criteria are applied; however, low levels of cardiorespiratory fitness should be considered when calculating an appropriate ramp rate.     

Biochemical changes in relation to a maximal exercise test in patients with fibromyalgia

Summary. Patients with fibromyalgia often complain of fatigue and pain during exercise and of worsening of pain days after exercise. The aim of the study described here was to determine if abnormal changes in potassium or lactate could be observed during an exercise test in fibromyalgia. Whether an abnormal incline in plasma creatine kinase or myoglobin could be observed days after the test was studied also. Fifteen female fibromyalgia patients and 15 age- and sex-matched controls performed a stepwise incremental maximal bicycle-ergometer test. Blood samples were collected from a catheter in a cubital vein. The changes in heart rate, potassium levels, and haematocrit during the exercise test were similar in the two groups. The maximal obtained lactate concentration was 4-2 mmol 1^-1 (3–5-5-6) in the patients as compared to 4–9 mmol l^-1 (3–9-5-9) in the controls (NS). The estimated anaerobic threshold of 2 mmol 1^-1 was reached at a heart rate of 124 min^-1 in the patients with fibromyalgia as compared to 140 min^-1 in the controls (P= 0–02). In relation to workload, the patients scored higher on a Borg scale for perceived exertion during exercise, but if the Borg score was related to lactate no significant difference was found. The patients reported 86% and 79% of maximal pain in the thighs on the visual analogue scale 1 and 2 days after the test, but the creatine kinase and myoglobin concentrations were not increased.,     

Quantitative Determination of Proteinuria by Closs’ Polythionate Method

A methodological investigation of the glucose oxidase method for determination of glucose is described. The importance of eliminating substances reducing H₂O₂ generated from glucose and other substances causing unspecific oxidation of the chromogen is emphasized. On the basis of this study a method has been constructed which gives accurate glucose values in whole blood, plasma, and red blood cells.     

Day‐to‐day variation in oxygen consumption at submaximal loads during ergometer cycling by adolescents

The day‐to‐day variation in oxygen consumption (V˙O₂) during ergometer cycling by 20 healthy adolescents, 10 females and 10 males, was measured using indirect calorimetry. The two sets of measurements were performed on two consecutive days. Great care was taken to minimize possible disturbing factors. Cycling started at 50 and 100 W for female and male adolescents, respectively. The load was increased at a rate of 5 W 30 s^?1. In order to reach steady state, the load was kept constant for 3·5 min twice during the cycling session, at 100 and 130 W for the females and at 130 and 160 W for the males. Cycling continued until exhaustion. The maximal loads were 196 W (mean) and 271 W (mean) for females and males, respectively. At the maximal loads the day‐to‐day variation (±2 SD) in oxygen consumption (V˙O₂) was ±330 ml min^?1 for females and 390 ml min^?1 for males. At the submaximal loads the day‐to‐day variation in heart rate (HR) was 9·3 beats min^?1 (±2 SD) (coefficient of variation, CV=3·4% at 130 W) for both sexes. The day‐to‐day variation in oxygen consumption (V˙O₂) was ±199 ml min^?1 (±2 SD) at the different submaximal loads and did not differ between female and male adolescents (CV=5·7% at 130 W). This natural day‐to‐day variation must be taken into consideration when using a submaximal ergometer cycling test for the evaluation of physical capacity in the two sexes.     

Cardiorespiratory effects of warm water immersion in elderly patients with chronic heart failure

BACKGROUND: Hydrotherapy might be included in the rehabilitation of patients with chronic heart failure (CHF), but little is known about the acute cardiorespiratory reaction in warm water. The aim of this study was to assess the acute cardiorespiratory effect of immersion in warm water, in a clinical setting, in elderly patients with CHF compared with healthy age and sex matched persons. METHODS: Twelve patients (three females) with CHF, NYHA II-III, age 64 +/- 6 years, and 12 healthy subjects were studied. Cardiorespiratory changes, on land and in a temperature-controlled swimming pool (33-34 degrees C) were assessed during rest and exercise, in a sitting position, using continuous gas analyses. RESULTS: There were no significant differences, land versus water, in carbon dioxide production, total ventilation, respiratory frequency, respiratory exchange ratio, heart rate or blood pressure in either of the groups. A significant difference was found in oxygen uptake, at rest, land versus water in patients with CHF in comparison with healthy subjects (-0.2 +/- 0.4 versus +0.3 +/- 0.6 ml kg(-1) min(-1), P < 0.01). Oxygen kinetics (tau) increased significantly (P = 0.01) in both groups during exercise in water. CONCLUSION: Hydrotherapy was well tolerated and the vast majority of the cardiorespiratory responses, during warm water immersion in a clinical setting, are similar in patients with CHF compared with healthy subjects. However, further larger studies, are needed to better understand the physiological reactions during hydrotherapy.     

Differences in muscle strength after ACL reconstruction do not influence cardiorespiratory responses to isometabolic exercise

Objectives

To investigate whether the muscle strength decrease that follows anterior cruciate ligament (ACL) reconstruction would lead to different cardiorespiratory adjustments during dynamic exercise.

Method

Eighteen active male subjects were submitted to isokinetic evaluation of knee flexor and extensor muscles four months after ACL surgery. Thigh circumference was also measured and an incremental unilateral cardiopulmonary exercise test was performed separately for both involved and uninvolved lower limbs in order to compare heart rate, oxygen consumption, minute ventilation, and ventilatory pattern (breath rate, tidal volume, inspiratory time, expiratory time, tidal volume/inspiratory time) at three different workloads (moderate, anaerobic threshold, and maximal).

Results

There was a significant difference between isokinetic extensor peak torque measured in the involved (116.5±29.1 Nm) and uninvolved (220.8±40.4 Nm) limbs, p=0.000. Isokinetic flexor peak torque was also lower in the involved limb than in the uninvolved limb (107.8±15.4 and 132.5±26.3 Nm, p=0.004, respectively). Lower values were also found in involved thigh circumference as compared with uninvolved limb (46.9±4.3 and 48.5±3.9 cm, p=0.005, respectively). No differences were found between the lower limbs in any of the variables of the incremental cardiopulmonary tests at all exercise intensities.

Conclusions

Our findings indicate that, four months after ACL surgery, there is a significant deficit in isokinetic strength in the involved limb, but these differences in muscle strength requirement do not produce differences in the cardiorespiratory adjustments to exercise. Based on the hypotheses from the literature which explain the differences in the physiological responses to exercise for different muscle masses, we can deduce that, after 4 months of a rehabilitation program after an ACL reconstruction, individuals probably do not present differences in muscle oxidative and peripheral perfusion capacities that could elicit higher levels of peripheral cardiorepiratory stimulus during exercise.     

Repeatability of measurements of oxygen consumption,heart rate and Borg's scale in men during ergometer cycling

The coefficient of repeatability (COR), expressed as 2-SD of differences, was calculated between two measurements of oxygen consumption (V O2), heart rate (HR) and rating of perceived exertion (RPE) during ergometer cycling by men. The two sets of measurements were performed 5 to 6 weeks apart. Nineteen healthy men performed an incremental maximal exercise test on an ergometer cycle. The load started at 50 W and increased by 5 W 20 s-1 until exhaustion was reached. At 40% of the individual maximum load of the pretest, the load was kept constant for 4 min in order to reach steady state. Gas measurements were recorded continuously by computerized instrumentation. The HR was monitored with electrocardiography (ECG) and the perceived exertion was evaluated using Borg's scale. The COR of V O2 at sub-maximal load was 14% and at maximum load 11%. The values in absolute figures were 209 and 332 ml min-1. The corresponding COR of the HR was 16% at sub-maximum load and 6% at maximum load, and an evaluation of the perceived exertion yielded CORs in absolute values of 4.8 and 1.3, respectively. The COR for V O2, HR and ratings of perceived exertion when cycling on an ergometer cycle thus indicate a better agreement between the measurements at maximum load. The COR of the heart at sub-maximal loads must be kept in mind when using HR for estimation of V O2max. The reported findings should be considered when using tests on an ergometer cycle for evaluating exercise capacity.     

Reference values for cardiopulmonary exercise testing in healthy subjects – an updated systematic review

Introduction: Reference values for cardiopulmonary exercise testing (CPET) parameters provide the comparative basis for answering important questions concerning the normalcy of exercise responses in patients, and significantly impacts the clinical decision-making process.

Areas covered: The aim of this study was to provide an updated systematic review of the literature on reference values for CPET parameters in healthy subjects across the life span.

A systematic search in MEDLINE, Embase, and PEDro databases were performed for articles describing reference values for CPET published between March 2014 and February 2019.

Expert opinion: Compared to the review published in 2014, more data have been published in the last five years compared to the 35 years before. However, there is still a lot of progress to be made. Quality can be further improved by performing a power analysis, a good quality assurance of equipment and methodologies, and by validating the developed reference equation in an independent (sub)sample. Methodological quality of future studies can be further improved by measuring and reporting the level of physical activity, by reporting values for different racial groups within a cohort as well as by the exclusion of smokers in the sample studied. Normal reference ranges should be well defined in consensus statements.     

运动试验后心率恢复与冠心病患者心肺功能及生存质量的相关性研究

目的:探讨心肺运动试验终止2min时的心率恢复情况与冠心病患者心肺功能及生存质量(QOL)的相关性.方法:纳入87例临床经冠脉造影检查而确诊为冠心病的住院患者,行心肺运动试验评估,按照运动试验终止2min时的心率恢复值(HRR2),将其分为以下两组:①HRR2≥42bpm的正常组35例;②HRR2＜ 42bpm的异常组52例.比较两组患者的静息心率(RHR)、峰值摄氧量(peak VO2)、无氧阈(AT)、峰值通气量(peak VE)和峰值功率(peakpower),以及简明健康量表(SF-36)评分结果.结果:HRR2正常组冠心病患者的RHR明显高于HRR2正常组患者(P＜ 0.05);HRR2异常组冠心病患者运动试验过程中的peak VO2、AT、peak power结果均显著低于HRR2正常组(P＜ 0.01,P＜ 0.05,P＜0.05),而两组间peak VE相比则差异无显著性(P＞ 0.05);HRR2正常组冠心病患者的SF-36评分显著低于HRR2正常组,主要表现在生理功能(PF)、生理职能(RP)、总体健康(GH)、活力(VT)、社会功能(SF)等5个维度方面.结论:运动试验后的心率恢复与冠心病患者心肺功能及QOL有一定相关性.心率恢复异常的冠心病患者静息心率水平更高,运动时的心肺储备和有氧代谢能力更差.HRR2可以作为预测冠心病患者心肺功能及QOL的可靠指标.     

实施浅层吸痰对机械通气新生儿的疗效观察

目的比较浅层吸痰与传统吸痰对机械通气新生儿心率、血氧饱和度及吸痰后刺激的影响,探讨最佳的吸痰方式。方法两组新生儿分别采用传统吸痰法和浅层吸痰法吸痰,并比较吸痰前1min、吸痰结束时及吸痰后1min、2min、3min新生儿的心率、血氧饱和度和呛咳发生率。结果浅层吸痰法新生儿心率、血氧饱和度在吸痰前后均无明显变化,未发生呛咳;吸痰结束时及吸痰结束后1min、2min两组新生儿的心率、血氧饱和度差异均具有统计学意义(P<0.01)。结论采用浅层吸痰能有效保持机械通气新生儿的心率、血氧饱和度的平稳和有效减少呛咳。     

Assessment of exercise capacity in women with type 2 diabetes

The primary aim of this study was to compare the maximal oxygen uptake as evaluated from a submaximal exercise test (EVO2peak) to direct measurements of VO2peak during a maximal exercise test as means of monitoring the aerobic endurance capacity in women with type 2 diabetes (T2D). Twenty-seven women with T2D participated in the study. The program consisted of combined group training 1 h twice a week during 12 weeks and walks 1 h per week. EVO2 max was estimated using a submaximal exercise test on a bicycle ergometer ad modum Astrand. VO2peak and maximal work rate were measured using an incremental maximal exercise test on an electrically braked bicycle ergometer at baseline and after 6 and 12 weeks. EVO2peak was higher than VO2peak at baseline and significantly higher at 12 weeks (EVO2peak1.92+/-0.54 l min(-1), VO2peak 1.41+/-0.36, P<0.005). Maximal work rate increased significantly after 12 weeks (12+/-15, P<0.005) compared to baseline. The main finding of this study was that EVO2peak assessed using a submaximal exercise test, systematically overestimated VO2peak. The combined group training increased maximal work rate but not VO2peak. This is likely to reflect peripheral adaptation to exercise and/or improved mechanical efficiency.