Frequência cardíaca de recuperação, duplo produto da pressão arterial e variabilidade da frequência cardíaca em pessoas com lombalgia crônica inespecífica

Abstract

Nonspecific chronic low back pain (CLBP) is associated with increased sympathetic activity, which elevates heart rate (HR) and impairs cardiovascular recovery. Objective: To analyze cardiovascular responses and heart rate variability (HRV) in individuals with CLBP, comparing them with those of individuals without low back pain. Materials and Methods: This cross-sectional study evaluated 23 individuals with CLBP and 28 healthy, sedentary controls aged between 18 and 45 years. Participants were voluntarily recruited from local communities and the university and divided into two groups based on the presence or absence of CLBP, confirmed through clinical evaluation and validated tools such as the Numeric Pain Scale and the Roland-Morris Disability Questionnaire. Cardiovascular parameters, including Heart Rate Recovery (HRR), Double Product of Blood Pressure (DPBP), and Heart Rate Variability (HRV), were analyzed during rest and physical exertion. All procedures adhered to ethical guidelines approved by the UFMA Ethics Committee (CAAE: 14783219.2.0000.5087). Results: The control group (CG) exhibited significantly higher HRR across all evaluated periods (11.04 ± 2.38; 31.7 ± 3.52; 39.2 ± 3.48; 46.3 ± 3.65; 54.1 ± 3.64; 61.6 ± 3.07, respectively) compared to the CLBP group. For DPBP, the CG showed significantly lower averages across the three evaluated moments (10036 ± 1081; 33220 ± 1687; 17549 ± 865, respectively). Regarding HRV, the CG demonstrated significantly higher values in all variables. In the time domain, before the exercise test, the CG exhibited higher mean RR intervals (713 ± 89.0 ms vs. 638 ± 111.2 ms; p = 0.010), as well as higher SDNN (41.0 ± 3.85 ms vs. 36.6 ± 3.52 ms; p < 0.001) and RMSSD (39.8 ± 4.54 ms vs. 29.5 ± 4.48 ms; p < 0.001). After the test, these differences persisted, with significantly lower SDNN in the CLBP group (6.70 ± 2.54 ms vs. 15.43 ± 4.60 ms; p < 0.001). In the frequency domain, before the test, the CG exhibited higher LF (506 ± 105.7 ms² vs. 454 ± 67.5 ms²; p = 0.029) and HF (511 ± 154.6 ms² vs. 360 ± 68.6 ms²; p < 0.001) values. After the exercise test, there was a sharper reduction in both components in the CLBP group, with LF (11.3 ± 4.59 ms² vs. 32.5 ± 18.25 ms²; p < 0.001) and HF (4.17 ± 3.55 ms² vs. 21.69 ± 15.40 ms²; p < 0.001), indicating reduced autonomic adaptability in the CLBP group. The LF/HF ratio was higher in the CLBP group before the test (1.28 ± 0.17 vs. 1.06 ± 0.33; p = 0.002) and remained elevated after the test (4.88 ± 3.51 vs. 1.78 ± 1.06; p < 0.001), suggesting greater relative sympathetic activity and reduced autonomic balance. Conclusion: Individuals with nonspecific chronic low back pain exhibit significant autonomic dysfunction, characterized by reduced heart rate variability and increased cardiac load, both at rest and during exertion