Association between Estimated Cardiorespiratory Fitness and Abnormal Glucose Risk: A Cohort Study.

BACKGROUND: Cardiorespiratory fitness (CRF) is a predictor of chronic disease that is impractical to routinely measure in primary care settings. We used a new estimated cardiorespiratory fitness (eCRF) algorithm that uses information routinely documented in electronic health care records to predict abnormal blood glucose incidence. METHODS: Participants were adults (17.8% female) 20-81 years old at baseline from the Aerobics Center Longitudinal Study between 1979 and 2006. eCRF was based on sex, age, body mass index, resting heart rate, resting blood pressure, and smoking status. CRF was measured by maximal treadmill testing. Cox proportional hazards regression models were established using eCRF and CRF as independent variables predicting the abnormal blood glucose incidence while adjusting for covariates (age, sex, exam year, waist girth, heavy drinking, smoking, and family history of diabetes mellitus and lipids). RESULTS: Of 8602 participants at risk at baseline, 3580 (41.6%) developed abnormal blood glucose during an average of 4.9 years follow-up. The average eCRF of 12.03 ± 1.75 METs was equivalent to the CRF of 12.15 ± 2.40 METs within the 10% equivalence limit. In fully adjusted models, the estimated risks were the same (HRs = 0.96), eCRF (95% CIs = 0.93-0.99), and CRF (95% CI of 0.94-0.98). Each 1-MET increase was associated with a 4% reduced risk. CONCLUSIONS: Higher eCRF is associated with a lower risk of abnormal glucose. eCRF can be a vital sign used for research and prevention.

Association Between Exercise Capacity and Late Onset of Dementia, Alzheimer Disease, and Cognitive Impairment.

OBJECTIVE: To address the association between exercise capacity and the onset of dementia, Alzheimer disease, and cognitive impairment. PATIENTS AND METHODS: For 6104 consecutive veteran patients (mean ± SD age: 59.2±11.4 years) referred for treadmill exercise testing, the combined end point of dementia, Alzheimer disease, and cognitive impairment was abstracted from the Veterans Affairs computerized patient record system. RESULTS: After mean ± SD follow-up of 10.3±5.5 years, 353 patients (5.8%) developed the composite end point at a mean ± SD age of 76.7±10.3 years. After correction for confounders in multivariate Cox proportional hazards regression, higher age at exercise testing (hazard ratio [HR]=1.08; 95% CI, 1.07-1.09; P<.001), current smoking (HR=1.44; 95% CI, 1.08-1.93; P=.01), and exercise capacity (HR=0.92; 95% CI, 0.89-0.96; P<.001) emerged as predictors of cognitive impairment. Each 1-metabolic equivalent increase in exercise capacity conferred a nearly 8% reduction in the incidence of cognitive impairment. Meeting the recommendations for daily activity was not associated with a delay in onset of cognitive impairment (HR=1.07; 95% CI, 0.86-1.32; P=.55). CONCLUSION: Exercise capacity is strongly associated with cognitive function; the inverse association between fitness and cognitive impairment provides an additional impetus for health care providers to promote physical activity.

The Impact of Fitness on Surgical Outcomes: The Case for Prehabilitation.

In recent years, a growing body of research has demonstrated that an individual's fitness level is a strong and independent marker of risk for cardiovascular and all-cause mortality. In addition, modest improvements in fitness through exercise intervention have been associated with considerable health outcome benefits. These studies have generally assessed fitness as a baseline marker in traditional epidemiological cohorts. However, there has been a recent recognition that fitness powerfully predicts outcomes associated with a wide range of surgical interventions. The concept of 'prehabilitation' is based on the principle that patients with higher functional capability will better tolerate a surgical intervention, and studies have shown that patients with higher fitness have reduced postoperative complications and demonstrate better functional, psychosocial, and surgery-related outcomes. This review focuses on the impact of fitness on surgical outcomes and provides a rationale in support of routine application of prehabilitation in the management of patients undergoing surgery.

Heart rate response at the onset of exercise in an apparently healthy cohort.

BACKGROUND: The exercise test is a powerful non-invasive tool for risk stratifying patients with or suspected of having cardiovascular disease (CVD). Heart rate (HR) response during and following exercise has been extensively studied. However, the clinical utility of HR response at the onset of exercise is less understood. Furthermore, conflicting reports exist regarding whether a faster vs. slower HR acceleration represents a CVD risk marker. The primary study purpose was to describe HR acceleration early in exercise in apparently healthy individuals. METHODS: Retrospective analyses were performed in a sample (N = 947) representing a range of age and fitness (11-78 years; VO2peak 17-49 mL kg(-1) min(-1)). HR response was defined over the initial 7 min of the protocol. Associations between HR acceleration and CVD risk factors were also assessed. RESULTS: Mean increases in HR were 18 ± 9 and 23 ± 11 beats at minute one, for men and women, respectively (p < 0.05). After adjusting for gender and pre-exercise HR, only modest associations were observed between the change in HR at minute one and body mass index, resting blood pressure, cigarette smoking, physical activity, HR reserve, and cardiorespiratory fitness. CONCLUSION: There was wide variability in HR acceleration at the onset of exercise in this apparently healthy cohort. A lower increase in HR during the first minute of exercise was associated with a better CVD risk profile, including higher cardiorespiratory fitness, in apparently healthy individuals. These data suggest a greater parasympathetic influence at the onset of exercise may be protective in an asymptomatic population.

Noninvasive measurement of cardiac performance in recovery from exercise in heart failure patients

OBJECTIVE: To examine the association between cardiac performance during recovery and the severity of heart failure, as determined by clinical and cardiopulmonary exercise test responses. METHODS: As part of a retrospective cohort study, 46 heart failure patients and 13 normal subjects underwent cardiopulmonary exercise testing while cardiac output was measured using a noninvasive device. Cardiac output in recovery was expressed as the slope of a single exponential relationship between cardiac output and time; the recovery-time constant was assessed in relation to indices of cardiac function, along with clinical, functional, and cardiopulmonary exercise responses. RESULTS: The recovery time constant was delayed in patients with heart failure compared with normal subjects (296.7 + 238 vs. 110.1 +27 seconds, p <0.01), and the slope of the decline of cardiac output in recovery was steeper in normal subjects compared with heart failure patients (p,0.001). The slope of the decline in cardiac output recovery was inversely related to peak VO2 (r = -0.72, p<0.001) and directly related to the VE/VCO2 slope (r = 0.57, p,0.001). Heart failure patients with abnormal recovery time constants had lower peak VO2, lower VO2 at the ventilatory threshold, lower peak cardiac output, and a heightened VE/VCO2 slope during exercise. CONCLUSIONS: Impaired cardiac output recovery kinetics can identify heart failure patients with more severe disease, lower exercise capacity, and inefficient ventilation. Estimating cardiac output in recovery from exercise may provide added insight into the cardiovascular status of patients with heart failure.

The utility of cardiopulmonary exercise testing to detect and track early-stage ischemic heart disease.

Evidence demonstrating the potential value of noninvasive cardiopulmonary exercise testing (CPET) to accurately detect exercise-induced myocardial ischemia is emerging. This case-based concept report describes CPET abnormalities in an asymptomatic at-risk man with suspected early-stage ischemic heart disease. When CPET was repeated 1 year after baseline assessment, his cardiovascular function had worsened, and an anti-atherosclerotic regimen was initiated. When the patient was retested after 3.3 years, the diminished left ventricular function had reversed with pharmacotherapy directed at decreasing cardiovascular events in patients with coronary artery disease. Thus, in addition to identifying appropriate patients in need of escalating therapy for atherosclerosis, CPET was useful in monitoring progression and reversal of abnormalities of the coronary circulation in a safe and cost-effective manner without the use of radiation. Serial CPET parameters may be useful to track changes marking the progression and/or regression of the underlying global ischemic burden.

Exercise capacity and body mass as predictors of mortality among male veterans with type 2 diabetes.

OBJECTIVE: To demonstrate the relation of exercise capacity and BMI to mortality in a population of male veterans with type 2 diabetes. RESEARCH DESIGN AND METHODS: After excluding two underweight patients (BMI <18.5 kg/m2), the study population comprised 831 consecutive patients with type 2 diabetes (mean age 61 +/- 9 years) referred for exercise testing for clinical reasons between 1995 and 2006. Exercise capacity was determined from a maximal exercise test and measured in metabolic equivalents (METs). Patients were classified both according to BMI category (18.5-24.9, 25.0-29.9, and > or =30 kg/m2) and by exercise capacity (<5.0 or > or =5.0 maximal METs). The association among exercise capacity, BMI, other clinical variables, and all-cause mortality was assessed by Cox proportional hazards. Study participants were followed for mortality up to 30 June 2006. RESULTS: During a mean follow-up of 4.8 +/- 3.0 years, 112 patients died, for an average annual mortality rate of 2.2%. Each 1-MET increase in exercise capacity conferred a 10% survival benefit (hazard ratio 0.90 [95% CI 0.82-0.98]; P = 0.01), but BMI was not significantly associated with mortality. After adjustment for age, ethnicity, examination year, BMI, presence of cardiovascular disease (CVD), and CVD risk factors, diabetic patients achieving <5 maximal METs were 70% more likely to die (1.70 [1.13-2.54]) than those achieving > or =5 maximal METs. CONCLUSIONS: There was a strong inverse association between exercise capacity and mortality in this cohort of men with documented diabetes, and this relationship was independent of BMI.