Randomized trial of an internet-based computer-tailored expert system for physical activity in patients with heart disease.

BACKGROUND: The CardioFit Internet-based expert system was designed to promote physical activity in patients with coronary heart disease (CHD) who were not participating in cardiac rehabilitation. DESIGN: This randomized controlled trial compared CardioFit to usual care to assess its effects on physical activity following hospitalization for acute coronary syndromes. METHODS: A total of 223 participants were recruited at the University of Ottawa Heart Institute or London Health Sciences Centre and randomly assigned to either CardioFit (n = 115) or usual care (n = 108). The CardioFit group received a personally tailored physical-activity plan upon discharge from the hospital and access to a secure website for activity planning and tracking. They completed five online tutorials over a 6-month period and were in email contact with an exercise specialist. Usual care consisted of physical activity guidance from an attending cardiologist. Physical activity was measured by pedometer and self-reported over a 7-day period, 6 and 12 months after randomization. RESULTS: The CardioFit Internet-based physical activity expert system significantly increased objectively measured (p = 0.023) and self-reported physical activity (p = 0.047) compared to usual care. Emotional (p = 0.038) and physical (p = 0.031) dimensions of heart disease health-related quality of life were also higher with CardioFit compared to usual care. CONCLUSIONS: Patients with CHD using an Internet-based activity prescription with online coaching were more physically active at follow up than those receiving usual care. Use of the CardioFit program could extend the reach of rehabilitation and secondary-prevention services.

Motivational counselling for physical activity in patients with coronary artery disease not participating in cardiac rehabilitation.

BACKGROUND: Many patients with coronary artery disease (CAD) fail to attend cardiac rehabilitation following acute coronary events because they lack motivation to exercise. Theory-based approaches to promote physical activity among non-participants in cardiac rehabilitation are required. DESIGN: A randomized trial comparing physical activity levels at baseline, 6, and 12 months between a motivational counselling (MC) intervention group and a usual care (UC) control group. METHOD: One hundred and forty-one participants hospitalized with acute coronary syndromes not planning to attend cardiac rehabilitation were recruited at a single centre and randomized to either MC (n = 69) or UC (n = 72). The MC intervention, designed from an ecological perspective, included one face-to-face contact and eight telephone contacts with a trained physiotherapist over a 52-week period. The UC group received written information about starting a walking programme and brief physical activity advice from their attending cardiologist. Physical activity was measured by: 7-day physical activity recall interview; self-report questionnaire; and pedometer at baseline, 6, and 12 months after randomization. RESULTS: Latent growth curve analyses, which combined all three outcome measures into a single latent construct, showed that physical activity increased more over time in the MC versus the UC group (µ(add) = 0.69, p < 0.05). CONCLUSION: Patients with CAD not participating in cardiac rehabilitation receiving a theory-based motivational counselling intervention were more physically active at follow-up than those receiving usual care. This intervention may extend the reach of cardiac rehabilitation by increasing physical activity in those disinclined to participate in structured programmes.

Gender differences in satisfaction with life in patients with coronary heart disease: physical activity as a possible mediating factor.

The objective of the present study was to examine if time varying, mediating effect of physical activity plays an important role in the gender-satisfaction with life relationship. Six hundred four male and 197 female patients were included. Principal outcomes of interest were self-report satisfaction with life and physical activity at baseline, 6, 12 and 24 months. The Krull and MacKinnon procedure for hierarchical linear modeling showed that the change in physical activity mediated the gender-satisfaction with life over a 2 year period. Results from the current study suggest that increased physical activity partially explains why males report having increased well-being than females after hospitalization. This suggests that future interventions need to focus on reducing the gender disparity in physical activity to improve differences noted in satisfaction with life. If higher physical activity levels impact satisfaction with life positively, the importance of physical activity for female patients is warranted.

Who will be active? Predicting exercise stage transitions after hospitalization for coronary artery disease.

We describe transitions between exercise stages of change in people with coronary artery disease (CAD) over a 6-month period following a CAD-related hospitalization and evaluate constructs from Protection Motivation Theory, Theory of Planned Behavior, Social Cognitive Theory, the Ecological Model, and participation in cardiac rehabilitation as correlates of stage transition. Seven hundred eighty-two adults hospitalized with CAD were recruited and administered a baseline survey including assessments of theory-based constructs and exercise stage of change. Mailed surveys were used to gather information concerning exercise stage of change and participation in cardiac rehabilitation 6 months later. Progression from pre-action stages between baseline and 6 month follow-up was associated with greater perceived efficacy of exercise to reduce risk of future disease, fewer barriers to exercise, more access to home exercise equipment, and participation in cardiac rehabilitation. Regression from already active stages between baseline and 6 month follow-up was associated with increased perceived susceptibility to a future CAD-related event, fewer intentions to exercise, lower self-efficacy, and more barriers to exercise.

Correlates of physical activity change in patients not attending cardiac rehabilitation.

OBJECTIVE: Limited research has identified theoretical correlates of physical activity (PA) change in patients not receiving cardiac rehabilitation. The purpose of the present study was to determine whether changes in self-efficacy, PA intention, perceived severity and susceptibility, and PA benefits/barriers were associated with changes in PA over a 12-month period in these patients. METHODS: Patients (N = 555) not attending cardiac rehabilitation completed a psychosocial questionnaire in hospital and 6 and 12 months after hospitalization for a cardiac event. RESULTS: Hierarchical regression analyses showed that the increase in PA from baseline to 6 months was significantly related to an increase in self-efficacy and PA intentions and a decrease in the impact of health-related barriers. Furthermore, the decrease in PA from 6 to 12 months was significantly related to a decrease in health-related benefits and PA intentions and an increase in time and health-related barriers. Finally, the increase in PA from baseline to 12 months was significantly related to an increase in health-related benefits and intentions and a decrease in health-related barriers. CONCLUSIONS: Changes in PA levels over a 12-month period were associated with changes in various theoretical variables. Interestingly, the associations among these variables with PA varied as a function of time after hospitalization.

Determinants of physical activity after hospitalization for coronary artery disease: the Tracking Exercise After Cardiac Hospitalization (TEACH) Study.

BACKGROUND: Little is known about physical activity levels in patients with coronary artery disease (CAD) who are not engaged in cardiac rehabilitation. We explored the trajectory of physical activity after hospitalization for CAD, and examined the effects of demographic, medical, and activity-related factors on the trajectory. DESIGN: A prospective cohort study. METHODS: A total of 782 patients were recruited during CAD-related hospitalization. Leisure-time activity energy expenditure (AEE) was measured 2, 6 and 12 months later. Sex, age, education, reason for hospitalization, congestive heart failure (CHF), diabetes, and physical activity before hospitalization were assessed at recruitment. Participation in cardiac rehabilitation was measured at follow-up. RESULTS: AEE was 1948+/-1450, 1676+/-1290, and 1637+/-1486 kcal/week at 2, 6 and 12 months, respectively. There was a negative effect of time from 2 months post-hospitalization on physical activity (P<0.001). Interactions were found between age and time (P=0.012) and education and time (P=0.001). Main effects were noted for sex (men more active than women; P<0.001), CHF (those without CHF more active; P<0.01), diabetes (those without diabetes more active; P<0.05), and previous level of physical activity (those active before hospitalization more active after; P<0.001). Coronary artery bypass graft patients were more active than percutaneous coronary intervention (PCI) patients (P=0.033). CONCLUSIONS: Physical activity levels declined from 2 months after hospitalization. Specific subgroups (e.g. less educated, younger) were at greater risk of decline and other subgroups (e.g. women, and PCI, CHF, and diabetic patients) demonstrated lower physical activity. These groups need tailored interventions.

Contraction-induced muscle damage in humans following calcium channel blocker administration.

Following contraction-induced damage of skeletal muscle there is a loss of calcium homeostasis. Attenuating the damage-induced rise in myocellular calcium concentration may reduce proteolytic activation and attenuate other indices of damage; calcium channel blockers have been shown to be effective in this regard. The effect of administration of a calcium channel blocker (CCB), amlodipine, on indices of muscle damage following a unilateral 'damage protocol', during which subjects performed 300 maximal isokinetic (0.52 rad s(-1)) eccentric contractions with the knee extensors was investigated. The design was a randomized, double-blind crossover. On one occasion, prior to the damage protocol, subjects consumed CCB for 7 days prior to and for 7 days following the damage protocol. Biopsies were taken from the vastus lateralis prior to (baseline) and following the damage protocol at 4 h and 24 h post-damage. Isometric peak knee extensor torque was reduced (P < 0.05) immediately post-, 24 h post- and 48 h post-damage protocol compared to pre-exercise values with no effect of treatment. Desmin disruption was attenuated (P < 0.05) with CCB versus placebo at 4 h post-damage. Z-band streaming was significantly (P < 0.05) elevated compared to baseline at both times post-damage, but was lower with CCB at 4 h (P < 0.05). Damage resulted in increased inflammatory cell (macrophage) infiltration into skeletal muscle at both 4 h and 24 h post-damage, with no effect of CCB. Neutrophil number was elevated by the damage protocol, but was higher at 24 h post-damage in the CCB condition (P < 0.05). Creatine kinase (CK) activity was higher (P < 0.05) at 24 h and 48 h following the damage protocol compared to baseline, with no effect of treatment. In conclusion, the reduction in desmin disruption and Z-band streaming indicates that CCB attenuated, or delayed, the contraction-induced damage to sarcomeric proteins.

Variability in estimating eccentric contraction-induced muscle damage and inflammation in humans.

We studied five young healthy volunteers who performed a "damage protocol" consisting of 240 (24 sets x 10 repetitions/set) maximal isokinetic eccentric muscle contractions (30 degrees/s) on each leg one week apart. Biopsies were taken from the vastus lateralis on two occasions. Two biopsies were taken from within the same muscle 24h following the damage protocol. On a second occasion a single biopsy was taken from the contralateral leg at 24h following the same damage protocol. Biopsies at all three sites showed Z-band disruption, much greater (i.e., approximately 14-fold) than is typically observed in resting biopsies, with no significant differences (ANOVA) according to site location (within legs or between legs). The within-leg coefficient of variation (CV) was, however, 41 +/- 30%, and the between-leg CVs were 57 +/- 36% and 68 +/- 36%. Macrophage cells were also detected within the muscle, and cell numbers were not statistically different between biopsy sites. However, the within-biopsy CV = 52 +/- 19% and the between-biopsy CVs of 34 +/- 24% and 48 +/- 27%. We conclude that eccentric contraction-induced Z-band streaming and inflammatory cell response, as detected in muscle biopsy samples from humans, is highly variable with a CV of 40-70%.

Contraction-induced muscle damage is unaffected by vitamin E supplementation.

PURPOSE: Vitamin E supplementation may confer a protective effect against eccentrically biased exercise-induced muscle damage through stabilization of the cell membrane and possibly via inhibition of free radical formation. Evidence supporting a protective role of vitamin E after contraction-induced muscle injury in humans is, however, inconsistent. The present study sought to determine the effect of vitamin E supplementation on indices of exercise-induced muscle damage and the postexercise inflammatory response after performance of repeated eccentric muscle contractions. METHODS: Young healthy men performed a bout of 240 maximal isokinetic eccentric muscle contractions (0.52 rad.s-1) after being supplemented for 30 d with either vitamin E (N = 9; 1200 IU.d-1) or placebo (N = 7; safflower oil). RESULTS: Measurements of torque (isometric and concentric) decreased (P < 0.05) below preexercise values immediately post- and at 48 h post-exercise. Biopsies taken 24 h postexercise showed a significant increase in the amount of extensive Z-band disruption (P < 0.01); however, neither the torque deficit nor the extent of Z-band disruption were affected by vitamin E. Exercise resulted in increased macrophage cell infiltration (P = 0.05) into muscle, which was also unaffected by vitamin E. Serum CK also increased as a result of the exercise (P < 0.05) with no effect of vitamin E. CONCLUSION: We conclude that vitamin E supplementation (30 d at 1200 IU.d-1), which resulted in a 2.8-fold higher serum vitamin E concentration (P < 0.01), had no affect on indices of contraction-induced muscle damage nor inflammation (macrophage infiltration) as a result of eccentrically biased muscle contractions.