Continuous Ramp Protocol Research Articles

Abstract We147: The Utility of Cardiopulmonary Exercise Testing (CPET) Amongst Male and Female athletes to Differentiate Between Physiological Left Ventricular Enlargement and Mildly Depressed Resting Systolic Function and Athletic Individuals with Dilated Cardiomyopathy.

Background: Athletes frequently reveal a dilated left ventricle (LV),some also demonstrate a co-existent mildly depressed LV ejection fraction, raising the possibility of mild dilated cardiomyopathy (DCM). The maximal oxygen consumption(VO2max) is a valuable tool for assessing fitness, largely determined by cardiac output. References ranges derived from the general population, may have limitations when assessing athletes with primary myocardial disease. This study investigated the role of VO2max and VO2max predicted (V02pred) to differentiate between physiological LV dilatation and athletic individuals with DCM in male and female athletes. Methods: 147 male and 35 female athletes with dilated LV(mean age 35.4years, 34.5 years respectively) underwent a 25watt cycle ergometer continuous ramp protocol. 75% males and 67% females participated in endurance sports, remaining participating in mixed sports. 52 had mild DCM, 62 defined as healthy control athletes(dilated LV) and 68 were Grey zone (dilated LV and mildly depressed LVEF) Results: DCM males (N=39) revealed a lower mean VO2max than male control (N=46), 34.9ml/kg/min and 48ml/kg/min respectively (p value <0.001). DCM females(N=13) showed lower VO2max of 29.9ml/min/kg than female control (N=16) who revealed similar values to male controls (48 ml/kg/min)(p value <0.001). 62 male Grey zones and 6 female Grey zone revealed lower VO2max than controls 43.1ml/min/kg and 34.1ml/min/kg respectively. DCM females had lower VO2pred than control females 119% and 161% respectively but significantly higher than their male counterparts, means of 106% and 123% respectively (p value <0.001). Male and female grey zones had lower mean VO2pred than controls, 121% and 106% respectively. Higher VO2max of ≥38ml/kg/min and VO2pred of ≥120% gave a sensitivity, specificity of 84.7% and 77%respectively to differentiate healthy athletes and athletic DCMs in males and females. Only41.1% Grey zone athletes were able to achieve above these thresholds. Conclusion: Female athletes with dilated LV may reveal supranormal VO2max which can equal their male counterparts. Furthermore, athletic females with physiological or pathological LV dilatation can reveal higher VO2pred than male athletes. Most athletic DCM individuals show lower CPET parameters than controls athletes but can still achieve greater than normal measurements seen in healthy general population. VO2 may have a role in assisting in differentiating healthy athletes from athletic DCM.

Clinical Pediatric Exercise Laboratories, Reactive Balance, Sleep, and Muscle Stimulation Considerations

Clinical Pediatric Exercise Laboratories, Reactive Balance, Sleep, and Muscle Stimulation Considerations

Cardiopulmonary Exercise Testing in Evaluation of Patients of Chronic Obstructive Pulmonary Disease

Objective assessment of severity in patients with chronic obstructive pulmonary disease (COPD) is mainly limited to pulmonary function testing performed at rest. But, accurate assessment of exercise capacity in patients with COPD may be possible with cardiopulmonary exercise testing (CPET). Forty-three patients with stable COPD were included and were divided into three groups based upon the spirometry data as per the Global Initiative for Obstructive Lung Disease (GOLD) guidelines as follows: Group A: mild COPD, Group B: moderately severe COPD and Group C: severe COPD. Symptom-limited CPET was performed using treadmill on incremental continuous ramp protocol in all of them. Five patients (11.6%) had mild COPD; 16 (37.2%) had moderately severe COPD and the remaining 22 (51.6%) patients had severe COPD. Anaerobic threshold was attained in all the 43 patients. The dominant symptom at peak exercise were dyspnoea (n = 19) and both dyspnoea and leg fatigue (n = 7). The other causes of exercise limitation included dyspnoea with significant oxygen desaturation (n = 6); and dyspnoea with severe oxygen desaturation (n = 2). Six patients complained only of leg fatigue at peak exercise. A significant correlation between forced expiratory volume in the first second (FEV1) percent predicted and the predicted maximum oxygen uptake (VO2 max % predicted) was observed in all the three groups (r = 0.39, p = 0.011) but with marked variability of peak VO2 for a given degree of airflow obstruction. Twenty-three (53.5%) patients with low anaerobic threshold (< 30%) were identified as potential group likely to benefit from exercise training for pulmonary rehabilitation. Cardiopulmonary exercise testing is useful to determine the causes of exercise limitation and to assess the maximal exercise capacity of patients with COPD.

Association between muscle aerobic capacity and whole-body peak oxygen uptake.

Decline in skeletal muscle mitochondrial oxidative capacity (MOC) is associated with reduced aerobic capacity and increased risk ofcardiovascular and metabolicdisease. Measuring skeletal muscle MOC may be an alternative method to assess aerobic capacity, especiallyfor individuals unable to perform a whole-body maximum oxygen uptake protocol. In this study, linear regression analysis in two leg muscles was performed to determine whether MOC values could be used to predict whole-body peak oxygen uptake. MOC was measured with near infrared spectroscopy (NIRS) inthemedial gastrocnemius (MG) and vastus lateralis (VL) musclesof 26 participants (age, 27.1 ± 5.8years old). Whole-body peak oxygen uptake (VO2 peak) was determinedby indirect calorimetry during a continuous ramp protocol on a cycle ergometer. VO2 peak values were significantly correlated with the muscle recovery rate constant (k)ofthe MG (kMG,r = 0.59;p < 0.01) and VL (kVL,r = 0.63; p < 0.01) muscles. Summingrecovery rate constantsof both muscles together (kMG + kVL)improved thestrength of thecorrelation with VO2 peak (r = 0.78;p < 0.0001)andcouldexplain amajorityof the variance(R2 = 0.61)between the two measurements. Data suggest that NIRS can provide reliable MOC measurements on two leg muscles that correlate well with whole-body peak oxygen uptake.

Standardization of a Continuous Ramp Ergometer Protocol for Clinical Exercise Testing in Children.

Developing a standardized protocol for pediatric exercise laboratories is challenging. Our objective was to report normal pediatric values for a continuous non-steady state cycle ergometer ramp protocol to achieve 8-10min of exercise based on sex and weight. One hundred seventeen patients (117) [mean age 13 ± 2.8years, range 7-18years (51% male)] referred for chest pain with normal cardiac evaluation underwent cardiopulmonary testing on a cycle ergometer. Patients entered one of the four continuous ramp protocols (10, 15, 20, and 25W/min ramp) to achieve an expected peak workload of 3W/kg at an increase of 0.3 to 0.35W/kg/min. Exercise test outcomes measured included duration, peak heart rate, work, respiratory exchange ratio, peak oxygen consumption, peak blood pressure, and ventilatory anaerobic threshold. An exercise duration of 8-10min was achieved in a majority of the study population; however, interactions with age (older, longer duration) and sex (males, longer duration) were present. Using our algorithm (0.3-0.35W/kg×weight), we demonstrated four non-steady state ramp bike ergometer protocols (10, 15, 20, and 25W/min) that can be applied to males and females of different ages and weights to achieve an exercise duration of 8-10min.

Validation of a Ramp Running Protocol for Determination of the True VO2max in Mice.

In the field of comparative physiology, it remains to be established whether the concept of VO2max is valid in the mouse and, if so, how this value can be accurately determined. In humans, VO2max is generally considered to correspond to the plateau observed when VO2 no longer rises with an increase in workload. In contrast, the concept of VO2peak tends to be used in murine studies. The objectives of the present study were to determine whether (i) a continuous ramp protocol yielded a higher VO2peak than a stepwise, incremental protocol, and (ii) the VO2peak measured in the ramp protocol corresponded to VO2max. The three protocols (based on intensity-controlled treadmill running until exhaustion with eight female FVB/N mice) were performed in random order: (a) an incremental protocol that begins at 10 m.min−1 speed and increases by 3 m.min−1 every 3 min. (b) a ramp protocol with slow acceleration (3 m.min−2), and (c) a ramp protocol with fast acceleration (12 m.min−2). Each protocol was performed with two slopes (0 and 25°). Hence, each mouse performed six exercise tests. We found that the value of VO2peak was protocol-dependent (p < 0.05) and was highest (59.0 ml.kg 0.75.min−1) for the 3 m.min−2 0° ramp protocol. In the latter, the presence of a VO2max plateau was associated with the fulfillment of two secondary criteria (a blood lactate concentration >8 mmol.l−1 and a respiratory exchange ratio >1). The total duration of the 3 m.min−2 0° ramp protocol was shorter than that of the incremental protocol. Taken as a whole, our results suggest that VO2max in the mouse is best determined by applying a ramp exercise protocol with slow acceleration and no treadmill slope.

Skeletal Muscle Metabolism in Endurance Athletes with Near-Infrared Spectroscopy

To determine whether near-infrared spectroscopy (NIRS) measurements of muscle mitochondrial function could detect the expected differences between endurance-trained athletes (n = 8) and inactive subjects (n = 8). Muscle oxygen consumption (mV˙O2) of the vastus lateralis was measured with continuous-wave NIRS using transient arterial occlusions. The recovery rate of mV˙O2 after electrical stimulation was fit to an exponential curve, with the time constant (Tc) used as an index of mitochondrial capacity. Whole-body peak oxygen uptake was determined by indirect calorimetry during a continuous ramp protocol on a cycle ergometer. Whole-body peak oxygen uptake values for endurance-trained and inactive controls were 73.5 ± 9.1 and 33.7 ± 5.9 mL·kg·min, respectively (P < 0.001). The recovery rates of mV˙O2 after exercise for endurance training were 18.4 ± 3.2 and 18.8 ± 2.5 s, whereas those for inactive controls were 32.4 ± 5.2 and 34.9 ± 5.9 s for the shallow and deep channels, respectively (P < 0.001 for comparison between groups). Resting mV˙O2 was 0.52%·s ± 0.22%·s for endurance athletes and 0.77%·s ± 0.82%·s for inactive controls (P = 0.42). The recovery rates of mV˙O2 after exercise in endurance athletes were almost twofold faster than inactive subjects measured with NIRS, consistent with previous studies using muscle biopsies and magnetic resonance spectroscopy. Our results support the use of NIRS measurements of the recovery of oxygen consumption to assess muscle oxidative capacity.

Allometric scaling of peak power output accurately predicts time trial performance and maximal oxygen consumption in trained cyclists

ObjectiveThe purpose of this study was to determine if peak power output (PPO) adjusted for body mass0.32 is able to accurately predict 40-km time trial (40-km TT) performance.Methods45 trained male...

Physiologic and Psychological Responses of an Athlete Cycling 100+ Miles Daily for 50 Consecutive Days

INTRODUCTIONWe present the report of a young male athlete who cycled 100+ miles·d−1 for 50 consecutive days in the 50 United States. The purpose of this ultra-event, titled Ride for Your Life (RFYL), was to raise awareness and funding for cancer research and treatment. RFYL began August 18, 200

Aerobic capacity is associated with 100-day outcome after hepatic transplantation.

The shortage of donor organs highlights the need to better identify patients most likely to benefit from hepatic transplantation. Reduced aerobic capacity (decreased peak oxygen consumption [VO(2)] during symptom-limited cardiopulmonary exercise testing) is frequently present in cirrhosis. Peak VO(2) during cardiopulmonary exercise testing may predict short-term outcome after hepatic transplantation. Symptom-limited testing was performed on a cycle ergometer (continuous ramp protocol) and VO(2) determined using a metabolic cart. One hundred fifty-six patients were tested; 59 subsequently underwent hepatic transplantation. Results showed that survivors and nonsurvivors were similar in age, duration of liver disease, Child-Pugh score, MELD score, resting cardiovascular function, pulmonary function, and gas exchange. The 6 (10.2%) patients dying within 100 days of transplantation were more likely to have reduced aerobic capacity (peak VO(2) <60% predicted and VO(2) at anaerobic threshold [VO(2)-AT] <50% predicted peak VO(2)) compared to survivors (4/6 vs. 7/53, P <.01). Using a multiple logistic regression model controlling for duration and severity of liver disease and time to transplantation, reduced aerobic capacity was independently associated with 100-day mortality. In conclusion, reduced aerobic capacity during cardiopulmonary exercise testing is associated with decreased short-term survival after hepatic transplantation. Further study is needed to determine if cardiopulmonary exercise testing can be used to improve allocation of donor organs. To ensure optimum allocation of donor organs, it is important to identify patients most likely to benefit from transplantation. Investigators have identified a number of preoperative, intraoperative, and postoperative factors that predict increased risk for postoperative mortality. Unfortunately, predictive accuracy has not been high, and the timing of factor identification does not optimize organ utilization. Identification of predictors of survival at the time of listing for transplantation might lead to better resource allocation.

SEASONAL CHANGES IN POWER OF COMPETITIVE CYCLISTS

PURPOSE Coaches and sport scientists who use tests to monitor performance of athletes need to consider seasonal changes and random variation in performance when drawing conclusions about observed changes. We report here the seasonal changes and variability in power of competitive cyclists. METHODS 12 male cyclists performed tests of peak power (continuous ramp protocol) and mean power (simulated 4-km time trial) on a Kingcycle with SRM cranks in each of five sessions during three phases (base, pre-comp, comp) of a racing season. Repeated-measures analysis of logtransformed power provided mean changes in performance (%) between phases and within-cyclist variability in performance (as a coefficient of variation, CV) between sessions <2 wk apart and between sessions in different phases. RESULTS Peak power increased from the base phase to the pre-comp phase on average by 4.3%, and by a further 2.5% from the pre-comp to comp phase. Corresponding increases in 4-km mean power were 4.6% and 4.3%. The 95% likely limits for these changes were • ±2.5%. The CV for peak power was 1.3% for sessions separated by <2 wk and 1.2% for sessions in pre-comp and comp phases, but it increased to 3.5% for sessions between the base and other phases. Corresponding CV for mean power were 1.7%, 2.0% and 3.3%. Likely limits for CV were ∼ x0.7 to x1.7. CONCLUSIONS (a) The average cyclist had major gains in peak and mean power between phases of the season. (b) The CV show that there were substantial differences between individuals for changes between base and other phases. (c) We can monitor these changes, because they are larger than the CV for sessions <2 wk apart (which represent the smallest changes that we can monitor confidently in individuals between any sessions). (d) Interventions that might produce small but worthwhile changes in performance over a period of weeks-months need to be researched in pre-comp and comp phases, when the CV are small.

Low physical performance in obese adolescent boys with metabolic syndrome

To assess cardiorespiratory exercise function in obese children with and without metabolic syndrome (MS). Comparing three groups of subjects with different cardiovascular risk profiles. Twenty-two MS (body weight (mean+/-s.d.) 97.3+/-15.3 kg; age (mean+/-s.d.) 14.2+/-1.9 y), 17 obese (82.6+/-15.7 kg; 14.2+/-2.6 y) and 29 normal weight control (64.3+/-8.5 kg; 15.3+/-1.0 y) boys. Exercise duration (ED), resting heart rate (HR(0)), peak heart rate (HR(peak)), physical working capacity at 170 beat/min (PWC-170), peak oxygen consumption (VO(2peak)) and the lactic acidosis threshold (LAT) were determined on treadmill, using a continuous ramp protocol. ED (MS (mean+/-s.d.); 655+/-86 s; obese 703+/-64 s; control 750+/-0 s) in absolute value and PWC-170 normalised for body weight (139+/-40 w; 177+/-40 w; 211+/-40 w) were significantly shorter and lower in the MS group, as compared to obese and control groups (P<0.05). VO(2peak) (2.2+/-0.4 l/min; 2.4+/-0.5 l/min; 2.9+/-0.4 l/min) and LAT (1.3+/-0.4 l/min; 1.5+/-0.4 l/ min; 1.8+/-0.4 l/min) normalised for body weight, were significantly shorter and lower in the MS group, as compared to control group (P<0.05). HR(0) was significantly higher (P<0.05) in MS group than in obese and control groups (88+/-12 bpm; obese 78+/-10 bpm; 73+/-10 bpm). Cardiorespiratory exercise performance capacity in MS boys are reduced. It still remains to be elucidated whether the metabolic alterations or the decreased physical activity is responsible for the observed reduction in cardiorespiratory performance.

Stress echocardiography in hyperthyroidism.

Exertion symptoms occur frequently in subjects with hyperthyroidism. Using stress echocardiography, exercise capacity and global left ventricular function can be assessed noninvasively. To evaluate stress-induced changes in cardiovascular function, 42 patients with untreated thyrotoxicosis were examined using exercise echocardiography. Studies were performed during hyperthyroidism, after treatment with propranolol, and after restoration of euthyroidism. Twenty-two healthy subjects served as controls. Ergometry was performed with patients in a semisupine position using a continuous ramp protocol starting at 20 watts/min. In contrast to control and euthyroidism, the change in end-systolic volume index from rest to maximal exercise was lower in hyperthyroidism. At rest, the stroke volume index, ejection fraction, and cardiac index were significantly increased in hyperthyroidism, but exhibited a blunted response to exercise, which normalized after restoration of euthyroidism. Propranolol treatment also led to a significant increase of delta (delta) stroke volume index. Maximal work load and delta heart rate were markedly lower in hyper- vs. euthyroidism. Compared to the control value, systemic vascular resistance was lowered by 36% in hyperthyroidism at rest, but no further decline was noted at maximal exercise. The delta stroke volume index, delta ejection fraction, delta heart rate, and maximal work load were significantly reduced in severe hyperthyroidism. Negative correlations between free T3 and diastolic blood pressure, maximal work load, delta heart rate, and delta ejection fraction were noted. Thus, in hyperthyroidism, stress echocardiography revealed impaired chronotropic, contractile, and vasodilatatory cardiovascular reserves, which were reversible when euthyroidism was restored.

Impaired Cardiopulmonary Exercise Capacity in Patients With Hyperthyroidism

Hyperthyroidism (H) has been implicated as a primary cause of decreased exercise tolerance. To our knowledge, analysis of respiratory gas exchange, an efficient noninvasive method in evaluating cardiopulmonary capacity, has not been performed in patients with H. Using cardiopulmonary exercise testing, 12 consecutive women with Graves' H were examined and controlled in euthyroidism (E). Eighteen women with E, in whom cardiac catheterization had ruled out heart disease, served as control subjects (C). The ventilatory anaerobic threshold was determined by means of the V-slope method. Ergometry was performed with patients in a semisupine position using a continuous ramp protocol of 20 W/min. Echocardiography at rest was performed in all patients. In patients with H, heart rate at rest was higher than in patients with E (p < 0.05) and showed a markedly lower increase between rest and anaerobic threshold compared with E patients (p = 0.007) and C (p = 0.009). Work rate was reduced (H, 50% vs E, 70%; p = 0.038). In H patients, the anaerobic threshold occurred at 59.6% of maximal oxygen uptake and 72% in E patients, respectively (p = 0.024). In H patients, the linear regression of the heart rate to oxygen uptake ratio showed a reduced slope in comparison with E patients (p = 0.001) and C (p = 0.004). In patients with H, a reduced tidal volume (p = 0.021) and an increased respiratory rate (p = 0.003) in comparison to patients with E were demonstrated. Echocardiographically, H patients had an increased ejection fraction (p = 0.008) and a higher cardiac index (p = 0.008) in comparison with E patients. Analysis of respiratory gas exchange showed marked alterations of cardiopulmonary exercise capacity in H patients, which are reversible in E patients. The impaired chronotropic response during exercise might be the primary limiting factor of reduced work capacity in patients with H.

Four commonly utilized metabolic systems fail to produce similar results during submaximal and maximal exercise

This study evaluated the reproducibility of four commonly utilized metabolic systems. The metabolic carts and associated electronic cycle ergometers were: (1) the Q‐PLEX I/Corival, (2) SensorMedics 2900/Ergometrics, (3) Medical Graphics Corporation (MGC) 2001/Mijnhardt, and (4) CPX/Medifit. Five individuals (mean age, 32 years; weight, 74 kg; height, 179 cm) experienced in graded exercise testing participated. Duplicate submaximal and maximal protocols were completed on separate days with all four systems. The submaximal power outputs averaged 85, 135, and 190 W and were each 4 minutes in duration. A maximal effort was achieved with a continuous ramp protocol (30 W/min) until exhaustion. All four systems demonstrated excellent reproducibility (usually 5% or less variation) for values reported during either submaximal or maximal exercise. These values were system dependent, however, as evident from a significant difference in submaximal and maximal pulmonary ventilation, oxygen consumption (VO2), carbon di...

Anaerobic threshold detection in patients with congestive heart failure

Anaerobic threshold measurements determined either invasively by analysis of arterial lactate concentration (lactate threshold) or noninvasively by respiratory gas exchange analysis (ventilatory threshold) were compared in patients with chronic congestive heart failure. Sixteen patients performed symptom-limited maximal exercise on a bicycle ergometer using a continuous ramp protocol with measurement of arterial lactate concentration at 1 minute intervals, and continuous breathby-breath analysis of respiratory gas exchange. A specific lactate threshold point was detected in only 7 patients. These 7 patients had significantly greater peak oxygen uptake than did the 9 in whom no specific lactate threshold point was detected (15.9 ± 1.0 vs 10.5 ± 0.5 ml/kg/min; p < 0.05). Ventilatory threshold significantly correlated with lactate threshold in these 7 patients. In the remaining 9 patients, neither lactate nor ventilatory threshold could be reliably determined with methods used in the present study.