Abstract
Purpose
To objectively assess, in stable cardiac patients, the adherence to physical activity (PA) recommendations using an accelerometer at 2 or 12 months after the discharge of cardiac rehabilitation program (CRP).
Methods
Eighty cardiac patients wore an accelerometer at 2 months (group 1, short-term adherence, n = 41) or one-year (group 2, long-term adherence, n = 39) after a CRP including therapeutic education about regular PA. PA was classified as “light” (1.8–2.9 Metabolic Equivalent of Task [METs]), “moderate” (3–5.9 METs), or “intense” (> 6 METs). Energy expenditure (EE, in Kcal) and time (min) spent in these three different levels were measured during a one-week period with the MyWellness Key actimeter (MWK). Motivational readiness for change was also assessed at the end of CRP. Patients were considered as physically active when a minimum of 150 min of moderate PA during the one-week period was achieved.
Results
Both groups were comparable, except for exercise capacity at the end of the CRP which was slightly higher in group 1 (167.5 ± 42.3 versus 140.7 ± 46.1 W, P < 0.01). The total weekly active EE averaged 676.7 ± 353.2 kcal and 609.5 ± 433.5 kcal in group 1 and 2, respectively. The time spent within the light-intensity range PA was 319.4 ± 170.9 and 310.9 ± 160.6 min, and the time spent within the moderate-intensity range averaged 157.4 ± 115.4 and 165 ± 77.2 min per week for group 1 and 2, respectively. Fifty-three percent and 41% of patients remained active in both groups respectively.
Conclusion
About half of the patients are non-adherent to PA after CRP and do not reach target levels recommended by physicians. The first 2 months following the discharge of CRP seem to be of outmost importance for lifestyle modifications maintenance, and further study monitoring more closely PA decrease could help to clarify the optimal follow-up options.
Résumé
Objectifs
Évaluer objectivement chez les patients cardiaques stables, l’observance aux recommandations d’activité physique (AP) à l’aide d’un accéléromètre, à court et à long terme à la fin d’un programme de rééducation cardiaque (PRC).
Méthodes
Quatre-vingts patients cardiaques ont porté un accéléromètre (MyWellness Key actimeter [MWK]) soit à deux mois (groupe 1, observance à court-terme, n = 41), soit à un an (groupe 2, observance à long terme, n = 39) après un PRC qui comprenait notamment des ateliers d’éducation thérapeutique portant sur les bénéfices d’une AP régulière. L’AP mesurée était classée comme « légère » (1,8–2,9 METs), « modérée » (3–5,9 METs), ou « intense » (> 6 METs). La dépense énergétique (DE, en Kcal) et le temps (minute) passé dans chacun des trois différents niveaux d’activité étaient mesurés pendant une période d’une semaine. La motivation au changement était également évaluée à la fin du PRC. Les patients étaient considérés comme actifs lorsqu’un minimum de 150 minutes d’AP modérée était réalisé au cours de la semaine.
Résultats
Les deux groupes étaient comparables à l’inclusion, sauf pour le pic de puissance lors du test d’effort final du PRC qui était légèrement supérieur dans le groupe 1 (167,5 ± 42,3 contre 140,7 ± 46,1 Watts [W], p < 0.01). La DE totale active hebdomadaire était de 676,7 ± 353,2 kcal pour le groupe 1 et 609,5 ± 433,5 kcal pour le groupe 2. Le temps passé à intensité légère était de 319,4 ± 170,9 minutes pour le groupe 1 et 310,9 ± 160,6 minutes pour le groupe 2, et le temps passé à intensité modérée était de 157,4 ± 115,4 minutes et 165 ± 77,2 minutes pour les groupes 1 et 2 respectivement. Cinquante-trois pour cent des patients du groupe 1 et 41 % des patients du groupe 2 sont restés actifs.
Conclusion
Environ la moitié des patients ne maintient pas une AP régulière après le PRC et ces patients n’atteignent pas les objectifs recommandés par les médecins. Les deux premiers mois après la sortie du PRC semblent être une période essentielle pour maintenir les changements d’habitudes de vie acquises au cours du séjour, et de futures études portant sur l’évaluation de la diminution d’AP permettraient de clarifier les meilleures options de suivi.
1
English version
1.1
Introduction
The benefits of exercise-based cardiac rehabilitation program (CRP) are now largely demonstrated, resulting in a 30% mortality decrease . Patients with cardiac disease are thus encouraged to engage in regular physical activity (PA) on a long-term basis, in order to obtain an optimal control of cardiovascular risk factors (CVRF), and improve physical capacity, social integration and quality of life . One of the main challenges of CRP is to obtain sustained modifications in lifestyle habits. Thus, one of the main objectives of a phase II CRP is to allow the patients to become autonomous in their practice of PA with a target of 150 min per week of moderate-intensity exercise (3–6 METs) or more, according to recent recommendations . Unfortunately, many barriers to PA have been identified in these patients such as comorbidities, age, exercise tolerance, anxiety and/or depression, social and ethnic origin . The EUROASPIRE studies showed a poor adherence to pharmacological treatment after cardiac event, as well as for the control of CVRF such as HTA, diabetes, and obesity . By extension, we could imagine that the same pattern of behavior might be observed with non-pharmacological intervention, such as PA. However, the question of sedentarity as a CVRF is often under-studied after CRP and the methodology to assess PA is often heterogeneous, favoring the measurement of the volume rather than precise parameters (minutes and exercise intensity).
Ayabe et al. showed that, during a phase III CRP, the amount of PA measured with accelerometers was appropriate on CRP days (299 ± 161 kcal with 59.7 ± 19.8, 26.4 ± 20.4, and 1.4 ± 3 min per day within the light, moderate, and vigorous range of PA, respectively), but patients failed to reach target levels on non-CRP days (177 ± 113 kcal, with 49.3 ± 19.3, 10.5 ± 14.6, and 0.4 ± 1.7 min per day within the light, moderate, and vigorous range of PA, respectively) , suggesting the weakness of adherence to PA in cardiac patients. Furthermore, in an hospital-based phase III CRP, it has been shown that, if a large majority (52%) of participants reached the minimal active goal on CRP days, only 8% reached the recommended level of weekly PA . More recently, Dolansky et al. showed, in sample of 248 adults who underwent a 12-week phase II CRP, that, less than 37% of the total sample adhered to a three-times-per-week exercise regimen after 1 year, irrespective of age/gender . However, they did not provide information about PA intensities and volume. Indeed, most of studies that assess the amount of PA after CRP were performed after phase III CRP, and had certain limits including the use of questionnaire or accelerometers in a short period, and the lack of description of the CRP content .
The objectives of this study were, firstly, to assess the short and long-term adherence to PA and, secondly, to document more accurately exercise intensity zones and volume in stable cardiac patients that participated to an ambulatory and comprehensive phase II CRP discharge.
1.2
Methods
1.2.1
Patients
This protocol was proposed to all patients referred to our cardiac rehabilitation unit at the end of their ambulatory phase II CRP. Exclusion criteria were: unstable angina, pacemaker, uncontrolled hypertension, severe arrhythmia or any neuro-orthopedic diseases that could have a major impact on exercise capacity. Patients were then prospectively and consecutively contacted either 2 months (group 2; n = 41) or 1 year (group 1; n = 39) after CRP discharge. All patients gave their written informed consent to participate in this protocol.
1.2.2
Cardiac rehabilitation program
All subjects underwent the same exercise program as outpatients (3 hours per day, three times per week, 21 non-consecutive days), including a 45-minute session on an ergocycle or treadmill and a 1-hour outdoor walking session, at the target heart rate (HR) determined during the stress test (60–80% of the heart rate reserve (HRR) . Furthermore, the patients participated in a 45-minute fitness, gymnastics, relaxation, Qi Gong or aquatic training sessions. Each session was monitored by a physiotherapist or kinesiologist and supervised by a cardiologist. In addition to the exercise protocol, the patients were involved in therapeutic education sessions conducted by a multidisciplinary team with interactive workshops on CVRF and treatment knowledge (3–4 hours a week), and a minimum of 5 hours of basic knowledge about PA (duration, volume, intensity and type of exercise prescribed according to the severity of their disease), in order to accompany the patients to autonomy in their PA. All patients received throughout the stay some advices on the importance of adhering to the exercise prescription based on maximal stress test performed at entry then, at discharge.
1.2.3
Measurements
Patients’ peak power output (PPO) and motivational readiness for change were assessed at the end of CRP ( Appendix A ). PA measurements were recorded in a cohort of cardiac patients at 2 months and 1 year after discharge from CRP, with an accelerometer worn for one full week. Anthropometrics parameters (BMI and waist circumference) were recorded at the beginning of the week.
1.2.4
Physical activity
PA was assessed using a small, lightweight single axis accelerometer (MyWellness Key [MWK], Technogym, Technogym S.p.A. – Via Perticari, 20 Gambettola [FC], Italy) worn on a waistband, every day throughout the waking period for a full week. The MWK allowed a daily reminder in the amount of PA accomplished. The validity of this device has been demonstrated previously . It provides a measurement of PA and time spent at different intensity levels: light: 1.8–2.9 METs, moderate: 3–5.9 METs and vigorous: ≥ 6 METs. The number of minutes spent at each intensity levels was averaged over the 7 days. In order to convert the data in total weekly active energy expenditure (EE) , we used the following methodology:
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the duration recorded by the accelerometer was multiplied by the mean EE of the corresponding zone (2.5 METs for light, 4.5 METs for moderate, and 7.5 METs for vigorous). These three values were added to obtain the total active weekly EE in METs, which were then converted to mL/O 2 per min (1 METs = 3.5 mL/O 2 per min). Finally, EE was converted into kilocalories according to the energy cost of 1 L of O 2 (1 L = 5 kcal).
1.2.5
Definition of sedentarity
Patients were considered as sedentary if they did not achieve a minimum of 150 min per week of exercise at moderate intensity (i.e., 3–6 METs) . In contrast, patients performing more than 150 min per week of exercise at moderate intensity were designed as “active”.
1.2.6
Motivational readiness for change
It was assessed using a five items questionnaire classifying patients into pre-contemplative, contemplative, decision, action, or maintenance state, during the interview at discharge .
1.2.7
Cardiopulmonary stress test
PPO was determined as the power reached at the last stage of a graded maximal exercise test on a cycle ergometer, performed under continuous 12-Lead ECG monitoring. The initial power was set at 30 W with increases of 15 W per min in coronary artery disease patients and 10 W per min in chronic heart failure patients. Blood pressure was checked every 2 min during the stress test and during the 6-minute recovery time .
1.2.8
Statistical analyses
Continuous variables were described as means and standard deviations. We compared the proportions of each pathology using a Chi 2 test with Yates correction. Total active EE, time spent at light and moderate intensity were compared between two groups using repeated measures Anova. Total active EE were compared between patients who were in the decision, action or maintenance using repeated measures Anova. The patients classified in each state were compared using Chi 2 tests. We looked for associations between the final PPO and the total active EE or the moderate-intensity PA time. The threshold for significance was set at P < 0.05. The analyses were done using Statview ® 5.1 software (SAS institute Inc. North Carolina, USA).
1.3
Results
1.3.1
Patient’s characteristics
Eighty-two patients were included ( Table 1 ). Among patients enrolled in this study and who accepted to participate, only two patients dropped out because they moved in another far area. Briefly, the majority were middle-aged men (56.8 ± 11.6 years), overweight when they left the rehabilitation program (BMI: 27.4 ± 3.8 kg/m 2 ), and under optimal medical treatment according to their conditions and latest recommendations (i.e. β-blockers; angiotensin converting enzyme inhibitors (ACE) or angiotensin receptor blockers (ARB), anti-platelet agents and statins). They all had a high exercise capacity at the end of the CRP (PPO = 154 ± 45 Watts [W]). No differences between groups were noted, except for maximal heart rate and PPO.
| Total ( n = 80) | Group 1 ( n = 41) | Group 2 ( n = 39) | P value | |
|---|---|---|---|---|
| Age (years) | 56.8 ± 11.6 | 56.4 ± 12.1 | 57.3 ± 11.2 | ns |
| Gender (male/female) | 67 (83%)/14 (17%) | 34/7 | 33/7 | ns |
| Body mass index (kg/m 2 ) | 27.4 ± 3.8 | 27.2 ± 3.9 | 27.7 ± 3.8 | ns |
| Waist circumference (cm) | 96.7 ± 11.4 | 95.8 ± 12.1 | 97.6 ± 10.7 | ns |
| Disease | ||||
| Coronary disease | 66 (82,5%) | 32 | 34 | ns |
| Angioplasty | 55 (83.3%) | 27 | 28 | ns |
| Bridging | 8 (12.1%) | 5 | 3 | ns |
| Heart Failure (Ejection fraction = 41.1 ± 3.7 < 45%) | 6 (7.5%) | 2 | 4 | ns |
| Others a | 8 (10%) | 7 | 1 | ns |
| Hypertension | 19 (15.2%) | 8 | 11 | ns |
| Diabetes | 9 (7.2%) | 7 | 2 | ns |
| Exercise tolerance | ||||
| Peak power output (Watt) | 154 ± 45.9 | 167.5 ± 42.3 | 140.7 ± 46.1 | < 0.01 |
| Heart rate max (bpm) | 128.7 ± 19.5 | 133.9 ± 20 | 123.6 ± 17.6 | < 0.05 |
| Physical activity | ||||
| Moderate intensity (min/week) | 161.2 ± 146.3 | 157.4 ± 115.4 | 165 ± 177.2 | ns |
| Light intensity (min/week) | 315 ± 163.2 | 319.4 ± 170.9 | 310.7 ± 267.2 | ns |
a Others: valvulopathy, intermittent claudication. Values are expressed as mean and standard deviation or raw values and percentage.
1.3.2
Measurement of physical activity
Total mean weekly EE did not differ between groups (676.7 ± 353 and 609.5 ± 433 kcal in group 1 and 2, respectively) ( Table 2 ). The time spent at light intensity was 319.4 ± 170.9 ( n = 41) and 310.7 ± 55.5 ( n = 39) min, and time spent at moderate intensity was 157.4 ± 115.4 ( n = 41) and 165 ± 177.2 ( n = 36) min for group 1 and 2, respectively. Very few patients ( n = 8 in total group) engaged in vigorous activities (> 6 METs), corresponding to 166.2 ± 164.1 min.
| Group 1 | Group 2 | P value | |
|---|---|---|---|
| Time spent at different intensities | |||
| Light (min/week) | 319.4 ± 170.9 | 310.7 ± 267.2 | ns |
| Moderate (min/week) | 157.4 ± 115.4 | 165 ± 177.2 | ns |
| Vigorous (min/week) | ( n = 8); 166.2 ± 164.1 | ns | |
| Active energy expenditure | |||
| Light (kcal/week) | 325.1 ± 172.5 | 310.9 ± 160.6 | ns |
| Moderate (kcal/week) | 292.8 ± 229.5 | 308.5 ± 340.3 | ns |
| Total (kcal/week) | 676.7 ± 353.2 | 609.5 ± 433.5 | ns |
| Number of patients at moderate intensity | |||
| ≥ 150 minutes | 22 (53.6%) | 16 (41%) | ns |
| ≥ 120 minutes | 24 (58.5%) | 18 (46.1%) | ns |
| ≥ 90 minutes | 29 (70.7%) | 19 (48.7%) | 0.007 |
Only 53.6 and 41% of patients were considered as active (more than 150 min per week of moderate-intensity PA) in group 1 and 2. The percentage of patients exercising more than 120 min per week at moderate intensity were 58.5 and 46.1 in group 1 and 2, and the percentage of those exercising more than 90 min were 70.7 and 48.7 ( P = 0.007).
Total active weekly EE tended to be greater in group 1 relative to group 2 (676.7 ± 353.2 kcal versus 609.5 ± 433.5 kcal; non significant). There was no significant difference between the two groups for EE at moderate intensity (292.8 ± 229.5 and 284.7 ± 337 kcal in group 1 and 2, respectively), nor in light intensity (325.1 ±172.5 kcal) in group 1 versus 310.9 ± 160.6 kcal in group 2).
1.3.3
Associations between parameters
We found a low but significant association between total active weekly EE and PPO in total group ( r = 0.39; P = 0.0003). No association was found between PPO and EE at moderate activity. The patients who are in the decision, action or maintenance had similar total active EE. No association was found between age or anthropometrics parameters and PA ( Table 3 ).
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