Although the efficacy of cardiac rehabilitation (CR) is proven, the need to improve patients' adherence has emerged. There are only a few studies that have investigated the effect of sending text messages after a CR period to stimulate subjects' ongoing engagement in regular physical activity (PA). A randomized controlled pilot trial was conducted after CR, sending a daily PA text message reminder to an intervention group (IG), which was compared with a usual care control group (CG) during three months of follow-up. Thirty-two subjects were assessed pre- and post-study intervention with GPAQ, submaximal iso-watt exercise testing, a 30 s sit-to-stand test, a bilateral arm curl test, and a final survey on a seven-point Likert scale. A statistically significant difference in the increase of moderate PA time (Δ 244.7 (95% CI 189.1, 300.4) minutes, p < 0.001) and in the reduction of sedentary behavior time (Δ -77.5 (95% CI 104.9, -50.1) minutes, p = 0.004) was shown when the IG was compared with the CG. This was associated with an improvement in heart rate, blood pressure, and patients' Borg rating on the category ratio scale 10 (CR10) in iso-watt exercise testing (all p < 0.05). Furthermore, only the IG did not show a worsening of the strength parameters in the follow-up leading to a change of the 30 s sit-to-stand test with a difference of +2.2 (95% CI 1.23, 3.17) repetitions compared to CG (p = 0.03). The telemedical intervention has been appreciated by the IG, whose willingness to continue with regular PA emerged to be superior compared to the CG. Text messages are an effective and inexpensive adjuvant after phase 2 CR that improves adherence to regular PA. Further studies are needed to confirm these results in a larger patient population and in the long term.
Keywords: GPAQ; coronary heart disease; exercise testing; exercise training; ischemic cardiomyopathy; strength testing.