Heart rate behavior during an exercise stress test in obese patients

BACKGROUND AND AIMS

Heart rate (HR) response to exercise has not been fully described in the obese. We wanted to study the differences between obese and non-obese patients in HR behavior during an exercise stress test and to determine whether these differences influence exercise capacity.

METHODS AND RESULTS

We studied 554 patients (318 females) who underwent a treadmill exercise test. All subjects were in sinus rhythm. Patients with ischemic heart disease, with reduced ejection fraction and patients taking drugs that interfere with HR were excluded. The population included 231 patients with BMI<30 kg/m(2) (group 1), 212 patients who were unfit and obese (group 2) and 111 patients who were trained obese (group 3). Resting HR was similar in the various groups. Peak HR, HR recovery and chronotropic index were lower in obese subjects, regardless of their fitness level. Multivariate analysis showed that HR related variables were associated with age, BMI, height, hypertension and various pharmacologic treatments, while exercise capacity was strongly dependent on HR behavior, as well as on sex, age, BMI and diabetes.

CONCLUSION

Obese subjects have a marked impairment of HR behavior during exercise and in the recovery period, and the blunted increase in HR is the most important factor that influences exercise capacity.

A simple tool to predict exercise capacity of obese patients with ischaemic heart disease

OBJECTIVE

To define an equation that predicts exercise capacity taking into account body mass index (BMI).

DESIGN

Retrospective analysis and validation study of a multidisciplinary programme aimed at weight loss and physical rehabilitation.

SETTING

Tertiary referral hospital.

PATIENTS AND METHODS

372 consecutive obese participants (249 men) with stable ischaemic heart disease, aged mean 60.1 (SD 8.7) years, underwent a treadmill exercise test. BMI was 37.8 (4.5) kg/m(2). In the validation study the model was tested in 87 patients with similar characteristics.

RESULTS

Mean exercise intensity was 6.6 (SD 2.4) metabolic equivalents (METs). Multivariate linear regression analysis defined two simple models that considered exercise intensity as the dependent variable and a set of independent variables such as anthropometric measures, age and sex in the first one, plus associated clinical conditions and drug treatment in the second one. The correlation coefficients of the two models were R = 0.630 and R = 0.677, respectively. Age, BMI and sex were the strongest predictors of exercise capacity. The first derived equation efficiently predicted exercise capacity: in the validation study predicted exercise intensity was 6.3 (1.6) METs and attained exercise intensity was 6.3 (2.4) METs (p = 0.903) with a highly significant correlation (R = 0.534, p < 0.001).

CONCLUSION

BMI is an important determinant of exercise capacity of obese people with ischaemic heart disease. The use of a simple equation may help in predicting exercise capacity, in individualising exercise protocol and in setting up rehabilitation programs for obese patients.

Effect of chronic treatment with beta-blockers on resting energy expenditure in obese hypertensive patients during a low-calorie and physical training program

BACKGROUND AND AIM

To evaluate whether chronic treatment with beta-blockers influences resting energy expenditure (REE) and weight loss after a period of diet and physical activity in obese hypertensive patients.

METHODS AND RESULTS

Seventy-eight obese hypertensive patients (24 males and 54 females) aged 53.7 +/- 11.1 years with mean BMI of 42.4 +/- 5.8 kg/m2 were enrolled. Thirty-eight patients were using beta-blockers while 40 patients who had not received beta-blockers in the past 6 months were the control group. REE was measured with indirect calorimetric method. Total body fat mass, total body fat-free mass (FFM) and total body water (W) were determined by bioelectrical impedance analysis. Patients and controls underwent a structured physical training program and a hypocaloric diet for a period of 31.6 +/- 10.6 days. Measured REE in patients taking beta-blockers was 1818 +/- 309 kcal/24 h and 1853 +/- 348 kcal/24 h in patients not taking beta-blockers; p = non significant. Weight and BMI loss were similar between the two groups and were respectively -6.43 +/- 2.62 kg and -2.42 +/- 0.91 kg/m2 in the beta-blocker group and -7.49 +/- 3.10 kg, -2.78 +/- 1.03 kg/m2 in the non beta-blocker group. Body composition was similar in the two groups. In the comparison between patients treated with selective beta 1-adrenoceptors blockers and non selective beta-blockers we found a significant difference in REE (1704 +/- 283 vs 1974 +/- 278; p = 0.012) and in weight loss (-5.6 +/- 2.4 vs -7.5 +/- 2.7; p = 0.048) at the end of study.

CONCLUSIONS

Beta-blockers are not associated with a lower REE in obese subjects compared to other antihypertensive treatment. Use of non selective beta-adrenergic blockers is associated with a higher REE and weight loss compared to use of selective beta 1-adrenergic blockers. Non selective beta-blockers could be indicated among first choice drugs in hypertensive severely obese subjects without contraindications to beta-blockade.