Impaired heart rate response during incremental exercise in patients with acute myocardial infarction and after coronary artery bypass grafting: evaluation of coefficients with Karvonen's formula

Predicting a target exercise heart rate that reflects the anaerobic threshold in nonbeta-blocked hemodialysis patients: The Karvonen and heart rate reserve formulas

The aim of this study was to evaluate constants of the Karvonen (k) and heart rate reserve (HRR) (α) formulas that correspond to the anaerobic threshold (AT) to conveniently estimate the intensity of exercise therapy in nonbeta-blocked patients undergoing hemodialysis. Twenty-three patients undergoing hemodialysis performed cardiopulmonary exercise testing (CPX) and their HR at AT was measured. The predictor coefficients for a target HR corresponding to AT were calculated for each patient based on CPX. Interclass correlation coefficients (ICC) and Bland-Altman analysis were used to evaluate the reliability of the formulas. Mean values of coefficient k of the Karvonen formula and α of the HRR formula were 0.24 ± 0.11 and 17.4 ± 8, respectively. The target HR calculated with k = 0.24 and α = 17 had significant ICC between HR at AT (0.74 and 0.77, respectively; P < 0.05). Using the Karvonen and HRR formulas to determine a target HR corresponding to AT is a simple and easy method that can be used to develop exercise programs for hemodialysis patients.

Increased Heart Rate during Walk Test Predicts Chronic-Phase Worsening of Renal Function in Patients with Acute Myocardial Infarction and Normal Kidney Function

Chronic-phase worsening renal function (WRF) in patients with acute myocardial infarction (AMI) has been associated with poor prognosis. However, there is no consensus on either the method of prevention or the cause. The aim of this study was to determine factors predictive of chronic-phase WRF from the viewpoint of circulatory dynamics response to exercise during hospitalization of AMI patients without renal dysfunction on admission. We studied 186 consecutively AMI patients who underwent the 200-m walk test. Chronic-phase WRF was defined as a 20% decrease in estimated glomerular filtration rate (eGFR) from baseline to 8–10 months after AMI onset. Heart rate (HR) and systolic blood pressure recorded during the 200-m walk test were evaluated as circulatory dynamics responses. In total, 94 patients were enrolled. Multiple linear regression analysis showed that ΔHR (peak-rest) associated significantly with ΔeGFR (β = 0.427, p = 0.018). The receiver operating characteristic curve of ΔHR to predict chronic-phase WRF showed an area under the curve of 0.77, with a cut-off value of 22.0 bpm having a 95% sensitivity and 55% specificity. Among circulatory dynamics responses during exercise in the acute phase after AMI, ΔHR was an independent predictor of chronic-phase WRF.

Exercise training intensity determination in cardiovascular rehabilitation: Should the guidelines be reconsidered?

Aims

In the rehabilitation of cardiovascular disease patients a correct determination of the endurance-type exercise intensity is important to generate health benefits and preserve medical safety. It remains to be assessed whether the guideline-based exercise intensity domains are internally consistent and agree with physiological responses to exercise in cardiovascular disease patients.

Methods

A total of 272 cardiovascular disease patients without pacemaker executed a maximal cardiopulmonary exercise test on bike (peak respiratory gas exchange ratio >1.09), to assess peak heart rate (HRpeak), oxygen uptake (VO2peak) and cycling power output (Wpeak). The first and second ventilatory threshold (VT1 and VT2, respectively) was determined and extrapolated to %VO2peak, %HRpeak, %heart rate reserve (%HRR) and %Wpeak for comparison with guideline-based exercise intensity domains.

Results

VT1 was noted at 62 ± 10% VO2peak, 75 ± 10% HRpeak, 42 ± 14% HRR and 47 ± 11% Wpeak, corresponding to the high intensity exercise domain (for %VO2peak and %HRpeak) or low intensity exercise domain (for %Wpeak and %HRR). VT2 was noted at 84 ± 9% VO2peak, 88 ± 8% HRpeak, 74 ± 15% HRR and 76 ± 11% Wpeak, corresponding to the high intensity exercise domain (for %HRR and %Wpeak) or very hard exercise domain (for %HRpeak and %VO2peak). At best (when using %Wpeak) in only 63% and 72% of all patients VT1 and VT2, respectively, corresponded to the same guideline-based exercise intensity domain, but this dropped to about 48% and 52% at worst (when using %HRR and %HRpeak, respectively). In particular, the patient’s VO2peak related to differently elicited guideline-based exercise intensity domains ( P < 0.05).

Conclusion

The guideline-based exercise intensity domains for cardiovascular disease patients seem inconsistent, thus reiterating the need for adjustment.

[The daily living activities of the cardiac patient: Monocentre study]

BACKGROUND

The main aim of cardiac rehabilitation is for the patient to sustain physical activity at home. The daily living activities (DLA) are important to take into account.

AIM OF THE STUDY

Analyze the DLA of patients in CR.

PATIENTS AND METHODS

One thousand seven hundred and eighty patients (mean age: 60.9±11 years) followed a CR programme between 2010 and 2015. They were tested for several DLA with their cardiac frequency (CF). The observed CF was included in the Karvonen's formula, used for the prescription of physical activity.

RESULTS

The coefficient of Karvonen was situated between 0.54 to 0.69, which was compatible with the prescribed physical training. Nevertheless, when the maximal exercise capacity was less than 5 METs, the coefficients were higher (0.53-0.89).

CONCLUSION

It was useful to test the cardiac patients for DLA during a CR programme. The use of Karvonen's formula allowed to compare these exercises with recommended physical training. We must be prudent when the maximal physical capacity is less than 5 METs.

Programming exercise intensity in patients on beta-blocker treatment: the importance of choosing an appropriate method

AIM

To verify the usefulness of current recommended level of target exercise heart rate (HR) and of different HR-based methods for calculating target HR in patients with and without beta-blocker treatment.

METHODS

We studied 53 patients not treated with beta-blocker and 159 patients on beta-blocker treatment. All patients underwent a maximal exercise test with gas analysis, and first ventilatory threshold (VT1 or aerobic threshold), second ventilatory threshold (VT2 or anaerobic threshold), time of exercise, maximum load, metabolic parameters, HR at rest (HRrest), HRpeak, HR at VT1 (HRVT1) and at VT2 (HRVT2), and 75, 80, and 85% of HRmax (HR75%, HR80%, HR85%) were calculated. Exercise HR was also determined using the Karvonen formula, applying 60, 70, and 80% of the heart rate reserve (HRR) (HRKarv0.6, HRKarv0.7, and HRKarv0.8).

RESULTS

This study included 102 patients on a beta-blocker and 39 not treated with negative cronotropic effect drugs. Maximum load, metabolic parameters, HRrest, HRpeak, HRVT1, and HRVT2 were significantly lower in patients on beta-blocker treatment. The proportion of patients with a HR75%, HR80%, HR85%, ​​HRKarv0.6, HRKarv0.7, and HRKarv0.8 <VT1 and >VT2 was very high and depended on whether patients were on beta-blocker treatment.

CONCLUSIONS

Prescribed exercise intensity should be within VT1 and VT2, so that the efficacy and safety is guaranteed. If determining VT1 and VT2 is not possible, HR-based methods can be used, but with caution. In fact, there will be always a proportion of patients training below VT1 or above VT2. On the other hand, recommendations for patients on a beta-blocker should be different from patients not receiving a beta-blocker. Patients not treated with a beta-blocker should exercise at HRKarv0.7 or at HR85%. In patients on a beta-blocker, we recommend preferentially a target HR of HRKarv0.6 or HR80%.

Endurance exercise intensity determination in the rehabilitation of coronary artery disease patients: a critical re-appraisal of current evidence

In the care of coronary artery disease (CAD) patients, the benefits of exercise therapy are generally established. Even though the selected endurance exercise intensity might affect medical safety, therapy adherence and effectiveness in the rehabilitation of CAD patients in how to determine endurance exercise intensity properly remains difficult. The aim of this review is to describe the available methods for endurance exercise intensity determination in the rehabilitation of CAD patients, accompanied with their (dis)advantages, validity and reproducibility. In general, endurance exercise intensity can objectively be determined in CAD patients by calculating a fraction of maximal exercise tolerance and/or determining ventilatory threshold after execution of a cardiopulmonary exercise test with ergospirometry. This can be translated to a corresponding training heart rate (HR) or workload. In the absence of ergospirometry equipment, target exercise HR can be calculated directly by different ways (fraction of maximal HR and/or Karvonen formula), and/or anaerobic threshold can be determined. However, the use of HR for determining exercise intensity during training sessions seems complicated, because many factors/conditions affect the HR. In this regard, proper standardization of the exercise sessions, as well as exercise testing, might be required to improve the accuracy of exercise intensity determination. Alternatively, subjective methods for the determination of endurance exercise intensity in CAD patients, such as the Borg ratings of perceived exertion and the talk test, have been developed. However, these methods lack proper validity and reliability to determine endurance exercise intensity in CAD patients. In conclusion, a practical and systematic approach for the determination of endurance exercise intensity in CAD patients is presented in this article.

Special needs to prescribe exercise intensity for scientific studies

There is clear evidence regarding the health benefits of physical activity. These benefits follow a dose-response relationship with a particular respect to exercise intensity. Guidelines for exercise testing and prescription have been established to provide optimal standards for exercise training. A wide range of intensities is used to prescribe exercise, but this approach is limited. Usually percentages of maximal oxygen uptake (VO₂) or heart rate (HR) are applied to set exercise training intensity but this approach yields substantially variable metabolic and cardiocirculatory responses. Heterogeneous acute responses and training effects are explained by the nonuniform heart rate performance curve during incremental exercise which significantly alters the calculations of %HR_max and %HRR target HR data. Similar limitations hold true for using %VO_2max and %VO₂R. The solution of these shortcomings is to strictly apply objective submaximal markers such as thresholds or turn points and to tailor exercise training within defined regions.

Intensity level for exercise training in fibromyalgia by using mathematical models

Background

It has not been assessed before whether mathematical models described in the literature for prescriptions of exercise can be used for fibromyalgia syndrome patients. The objective of this paper was to determine how age-predicted heart rate formulas can be used with fibromyalgia syndrome populations as well as to find out which mathematical models are more accurate to control exercise intensity.

Methods

A total of 60 women aged 18-65 years with fibromyalgia syndrome were included; 32 were randomized to walking training at anaerobic threshold. Age-predicted formulas to maximum heart rate ("220 minus age" and "208 minus 0.7 × age") were correlated with achieved maximum heart rate (HRMax) obtained by spiroergometry. Subsequently, six mathematical models using heart rate reserve (HRR) and age-predicted HRMax formulas were studied to estimate the intensity level of exercise training corresponding to heart rate at anaerobic threshold (HRAT) obtained by spiroergometry. Linear and nonlinear regression models were used for correlations and residues analysis for the adequacy of the models.

Results

Age-predicted HRMax and HRAT formulas had a good correlation with achieved heart rate obtained in spiroergometry (r = 0.642; p < 0.05). For exercise prescription in the anaerobic threshold intensity, the percentages were 52.2-60.6% HRR and 75.5-80.9% HRMax. Formulas using HRR and the achieved HRMax showed better correlation. Furthermore, the percentages of HRMax and HRR were significantly higher for the trained individuals (p < 0.05).

Conclusion

Age-predicted formulas can be used for estimating HRMax and for exercise prescriptions in women with fibromyalgia syndrome. Karnoven's formula using heart rate achieved in ergometric test showed a better correlation. For the prescription of exercises in the threshold intensity, 52% to 60% HRR or 75% to 80% HRMax must be used in sedentary women with fibromyalgia syndrome and these values are higher and must be corrected for trained patients.