Self-reported physical activity (PA) provides inaccurate estimates of moderate-to-vigorous-intensity physical activity (MVPA) in patients with coronary artery disease (CAD) entering ambulatory cardiac rehabilitation (CR), according to a study published in the journal Biosensors.
“PA and sedentary behavior SB levels in healthy adults are predominately based on self-reporting measures, which generally overestimate PA but underestimate SB,” the researchers wrote. They sought to compare self-reported and objectively measured PA and SB in patients with CAD prior to out-patient CR.
The study comprised of 91 patients with CAD and assessed their PA using an accelerometer for eight days prior to CR, along with the short form of the international physical activity questionnaire.
According to the results, over half of patients (61%) were sedentary, for about eight hours out of each day. On average, they performed 63 min/day of moderate-to-vigorous-intensity physical activity (MVPA). The study found that males performed less daily light-intensity physical activity (-5%, p = 0.011), and performed more MVPA (+2%, p = 0.002) compared to females.
Maximal aerobic capacity was significantly associated with MVPA (Spearman rho = 0.483, p < 0.001) and MVPA > 10 min bouts (Spearman rho = 0.391, p < 0.001). Self-reported measures overestimated MVPA (total MVPA, +108 min/day, p < 0.001; MVPA > 10 min bouts, +152 min, p < 0.001) and underestimated SB (-174 min/day, p < 0.001) compared to objective measures. There was no significant correlation between methods in MVPA (Spearman rho = 0.147, p = 0.165)), MVPA > 10 min bouts (Spearman rho = -0.059, p = 576), and SB (Spearman rho = 0.139, p = 0.187). Quantitative analysis demonstrated the huge proportional bias for MVPA, MVPA > 10 min bouts, and SB.
The study did reported several limitations. Firstly, because patients were advised to wear the accelerometer during waking hours, this advisement have been interpreted differently by each patient and might have affected the total daily wear time. Secondly, self-reported measure of MVPA and SB using IPAQ-SF may have been influenced by the age of the patients. Thirdly, the accelerometer thresholds for LPA, MVPA, and SB were adopted from a previous study in healthy adults of similar age thus, inaccurate classification of PA and SB levels cannot be ruled out, the researchers noted. Lastly, the population of interested consisted mostly of male patients, which limited the translation of the findings.
The researchers concluded that: “Our findings demonstrate that self-reported physical activity provides inaccurate estimates of MVPA and SB in patients with CAD entering the ambulatory CR. This strongly supports the more objective assessments of daily PA, preferably using an accelerometer.”