The role of treadmill exercise testing in women

Treadmill exercise electrocardiogram (ECG) is one of the most commonly used noninvasive tests for the assessment of ischemic heart disease (IHD). Sex-specific challenges in diagnostic and prognostic tests methods for IHD outlined the importance of pretest probability evaluation and referral bias using risk-prediction charts available for both asymptomatic and symptomatic women. Accordingly, exercise ECG has been indicated as the initial test for the symptomatic women at intermediate risk of IHD who has a normal resting ECG and is capable of maximal exercise. However, the difficulties of using exercise testing for diagnosing IHD in women have led to an initial speculation that stress imaging may be preferred to standard stress testing. This editorial analyzed a large body of evidence on the diagnostic and prognostic powers of treadmill ECG and exercise myocardial perfusion imaging (MPI) according to new advanced imaging technologies.     

Serum insulin and glucose response to graded exercise in adults. Part II. The effect of exercise conditioning.

The effect of conditioning to severe exercise upon serum immunoreactive insulin levels (IRI) and serum glucose concentrations (GC) was studied in active and sedentary groups of middle-aged men. The responses of serum IRI and serum GC were determined during graded cycle ergometer exercise which required similar low and high relative work intensities, before (pre) and after (post) a four month physical fitness programme. Both groups demonstrated a marked decline in serum IRI during high intensity exercise from pre to post tests, and a tendency to maintain serum, GC (sedentary group) or elevate serum GC (active group) during exercise, following the conditioning programme. The data provides evidence of a bi-directional response of serum IRI and serum GC to graded exercise, with only minor modifications in the response patterns resulting from exercise conditioning.     

运动平板试验诊断无症状心肌缺血的临床价值

 目的 评价运动平板试验（treadmill exercise testing,TET）检出冠心病无症状心肌缺血(slient myocardial ischemia,SMI)的诊断价值。方法 对经动态心电图检查拟诊为SMI患者145例进行TET及冠状动脉造影(coronary angiography,CAG）检查,并以后者作为判定标准,计算TET诊断SMI的敏感性、特异性、准确性指数、阳性预测值及阴性预测值。结果 TET检出SMI的敏感性为89.3%,特异性为67.2%,准确性为80.0%,阳性预测值为78.9%,阴性预测值为82.0%。多支冠脉病变患者的运动平板试验阳性率与单支病变患者的对比差异无统计学意义(P>0.05)。女性运动平板试验假阳率高于男性(P <0.01)。结论 检出SMI的特异性较低,但敏感性较高,能较准确评价SMI 的缺血情况。     

Effects of anteriorly-loaded treadmill walking on dynamic gait stability in young adults

BackgroundAnteriorly-loaded walking is common in many occupations and may increase fall risk. Dynamic gait stability, defined by the Feasible Stability Region (FSR) theory, quantifies the kinematic relationship between the body’s center of mass (COM) and base of support (BOS). FSR-based dynamic gait stability has been used to evaluate the fall risk.Research questionHow does front load carriage affect dynamic gait stability, step length, and trunk angle among young adults during treadmill walking?MethodsIn this between-subject design study, 30 healthy young adults were evenly randomized into three load groups (0%, 10%, or 20% of body weight). Participants carried their assigned load while walking on a treadmill at a speed of 1.2 m/s. Body kinematics were collected during treadmill walking. Dynamic gait stability (the primary variable) was calculated for two gait events: touchdown and liftoff. Step length and trunk angle were measured as secondary variables. One-way analysis of variance was conducted to detect any group-related differences for all variables. Post-hoc analysis with Bonferroni correction was performed when main group differences were found.ResultsNo significant differences but medium to large effect sizes were found between groups for dynamic gait stability at touchdown (p = 0.194, η² = 0.114) and liftoff (p = 0.122, η² = 0.139). Trunk angle significantly increased (indicating backward lean) with the front load at touchdown (p < 0.001, η² = 0.648) and liftoff (p < 0.001, η² = 0.543). No significant between-group difference was found related to the step length (p = 0.344, η² = 0.076).SignificanceCarrying a front load during walking significantly alters the trunk orientation and may change the COM-BOS kinematic relationship and, therefore, fall risk. The findings could inform the design of future studies focusing on the impact of anterior load carriage on fall risk during different locomotion.     

Heat shock protein responses to eccentric weight or treadmill exercise in active young females

Previous studies have shown the increase of heat shock protein (HSP72) following exercise in animals. The purpose of this study was to examine the effect of type of exercise on HSP72 response in active young females. Nineteen female physical education students were randomly divided into two groups: an endurance training group (ETG) and a weight training group (WTG). The exercise protocol in the ETG included incremental running to exhaustion performed at 65–75% VO_2max on a treadmill with a 0% grade. The subjects in the WTG also performed 4 sets of eccentric contractions of elbow flexors: two sets of 25 reps at 50% 1RM and two sets of 15–20 reps at 60% 1RM. Blood sampling from antecubital vein was done at baseline level (rest), mid-exercise and 30 min post-exercise in the same conditions, after a 12–14 h overnight fast. The samples were sent to a laboratory and centrifuged, and the serum used to analyse variables. A sandwich **Elisa and enzymatic assay were used for determination of HSP72 values and creatine kinase (CK) respectively. The data were analysed with repeated measures, LSD post hoc and independent t-test at p<0.05. The results showed HSP72 level alterations in mid- and post-tests were only significant in the ERG in comparison with baseline values (p=0.007, p=0.03 respectively). In addition, HSP72 level alterations within the ETG and WTG were only significant mid-test. Also CK levels insignificantly increased and decreased in the ETG and WTG respectively. The CK alterations in mid- and post-tests were insignificant between groups. Thus these results suggest that eccentric weight exercise induces a further increase in HSP72 levels.     

Comparison of 201Tl SPET and treadmill exercise testing in patients with Kawasaki disease

About 4% of children with Kawasaki disease ultimately develop ischaemic heart disease. Therefore, the early detection, non-invasive monitoring and long-term follow-up of myocardial ischaemia are essential. We compared the sensitivity and specificity of 201Tl single photon emission tomography (SPET) and treadmill exercise in the detection of myocardial ischaemia in 23 patients (19 boys, 4 girls) with Kawasaki disease. They were divided into two groups according to the results of coronary angiography. Group I consisted of 11 patients with coronary abnormalities; Group II consisted of 12 patients with no coronary abnormalities. The sensitivity, specificity, false-positive and false-negative rates for detecting coronary arterial lesions were 72.7% (8/11), 58.3% (7/12), 38.5% (5/13) and 30% (3/10) for 201Tl SPET, and 45.5% (5/11), 100% (12/12), 0% (0/5) and 33.3% (6/18) for treadmill exercise, respectively. We conclude that 201Tl SPET is more sensitive than treadmill exercise for the detection of coronary arterial abnormalities, but that the specificity of treadmill exercise is better than that of 201Tl scintigraphy. Coronary artery lesions detected by coronary angiography have good concordance of ischaemic areas with perfusion defects detected by 201Tl SPET. When ischaemic findings on 201Tl SPET and/or positive treadmill exercise testing are noted, coronary angiography is strongly indicated to detect possible stenotic lesions in the coronary arteries.     

Serum insulin and glucose response to graded exercise in adults. Part I: the influence of fitness status.

The effect of acute exercise upon serum immunoreactive insulin levels (IRI) and serum glucose concentrations (GC) was studied in groups of middle-aged men of contrasting physical fitness status. Two groups of subjects, one active and one sedentary (both N = 11, mean age 44 years), performed a graded cycle ergometer exercise test in the post-absorptive state. Venous blood samples were taken at rest, during low and high work intensities, and after recovery. The response of serum IRI to exercise was similar in both groups of subjects with significant increases observed during exercise followed by a return to resting values during recovery. However, the magnitude of serum IRI response was lower in the active group. In contrast, the sedentary group demonstrated little or no change in serum GC during exercise, whereas significant increases in serum GC were observed during exercise in the active group.     

Effect of acute calcium slow-channel antagonism on the cardiorespiratory response to graded exercise testing

The effect of acute calcium slow-channel antagonism on the cardiorespiratory responses of 12 healthy males was studied during multistage maximal exercise testing. Oral diltiazem (60 mg), nifedipine (10 mg), verapamil (80 mg), and placebo were administered in a randomized double-blind crossover fashion 1.5 h before an intermittent multistage cycle ergometer exercise test. At peak effort, heart rate, pulmonary ventilation, CO2 production, and respiratory exchange ratio were not significantly modified by drug ingestion. In contrast, maximal O2 consumption (2.6% reduction, P less than 0.02) and performance time (6.4% reduction, P less than 0.02) were reduced by nifedipine. During submaximal exercise, the chronotropic response was accentuated by nifedipine but not by diltiazem or verapamil. Furthermore, nifedipine altered the relationship of percentage of maximal O2 consumption to percentage of maximal heart rate, and both the relative and absolute O2 consumption corresponding to 70% and 85% of the maximal heart rate were significantly reduced after nifedipine ingestion. The results indicated that in persons without symptomatic coronary artery disease exercise performed at a given percentage of the maximal heart rate will yield a lower than expected relative and absolute intensity in the presence of acute nifedipine-induced calcium slow-channel antagonism.     

Long-term prognostic value of myocardial perfusion imaging in octogenarians able to undergo treadmill exercise stress testing

Background

Although the use of myocardial perfusion imaging (MPI) for prognostic purposes in general population is well understood, its role in very elderly patients is not extensively studied.

Methods

247 octgogenarians (79% male, 56% previous myocardial infarction—MI or revascularization) who underwent treadmill exercise testing (TET) with MPI were studied. TET and MPI-related data were registered per patient and prospective follow-up was performed to document all cause death (ACD), cardiac death (CD), non-fatal MI, and late revascularization (LR). Kaplan-Meier and Cox-regression analysis were used to compute event-free survival and identify significant predictors of these events.

Results

After 7.3 years there were 48 deaths, 17 CDs, 8 MIs, and 21 LRs. 69 patients were classified as high and 103 as low risk by SSS with annual cardiac mortality rates of 5% and 0.9%, respectively. Differences between survival curves of SSS-based risk groups were significant for ACD, CD, CD/MI, and CD/MI/LR. Summed stress (SSS) and difference scores were the only significant predictors of all endpoints. LVEF and transient ischemic LV dilatation were significant predictors of CD and CD/MI. LVEF and all MPI variables were associated with the CD, MI, and LR endpoint while only Duke treadmill score and angina severity demonstrated such a relationship among TET variables.

Conclusions

In octogenarians, MPI provides effective long-term risk stratification for both hard (ACD, CD, CD/MI) and soft (CD/MI/LR) endpoints and should be preferred over simple TET.     

Abnormal heart rate recovery immediately after treadmill testing: Correlation with clinical, exercise testing, and myocardial perfusion parameters

BACKGROUND: The increase in heart rate during exercise is considered to be attributed to sympathetic system activation combined with parasympathetic withdrawal. The prognostic importance of the chronotropic response to exercise and heart rate recovery 1 minute after exercise has already been established. The purpose of this study was to evaluate heart rate recovery as an index of myocardial ischemia, by correlating heart rate recovery with known parameters of myocardial ischemia. METHODS AND RESULTS: Included in the study were 304 consecutive patients (73% men), aged 34 to 82 years. Patients whose heart rate recovery value or myocardial perfusion imaging could have been influenced by factors other than ischemic disease were excluded from the study. The patients underwent single photon emission computed tomography myocardial perfusion imaging combined with symptom-limited exercise testing with thallium 201 or technetium 99m tetrofosmin. The value for heart rate recovery was defined as the decrease in heart rate from peak exercise to 1 minute after termination of exercise. For semiquantitation of the scintigram, the uptake of the radiotracer was graded on a scale from 0 to 4. Twenty-one beats per minute was defined as the lowest normal value for heart rate recovery. We found 74 patients (24%) with an abnormal value. We also found a significant correlation between heart rate recovery 1 minute after exercise and stress myocardial perfusion score. In addition, there was a statistically significant relationship between heart rate recovery and chronotropic variables. Patients with an abnormal value of heart rate recovery were generally of an older age, were more likely men, had a higher frequency of risk factors for coronary artery disease, were mostly taking cardioactive medications, had lower efficiency during treadmill testing, and had more pathologic findings on the scintigram. CONCLUSIONS: Myocardial ischemia, as assessed by myocardial perfusion imaging, is an important correlate of heart rate recovery. There is a significant correlation between chronotropic variables during exercise testing and heart rate recovery 1 minute after exercise. It seems that the heart rate recovery value 1 minute after peak exercise may be considered a reliable index of the severity of myocardial ischemia.     

85% of maximal age-predicted heart rate is not a valid endpoint for exercise treadmill testing

Background  

Exercise testing should be symptom-limited. Nevertheless, 40% of clinical laboratories applying for ICANL accreditation use 85% of maximal age-predicted heart rate (MPHR) as the primary exercise endpoint. We hypothesized that this approach importantly may underestimate exercise capacity and inducible ischemia.