Associação entre medidas de variabilidade da frequência cardíaca e a capacidade funcional avaliada por meio de um teste de campo em indivíduos com diabetes tipo 2: um estudo exploratório

Abstract

Objective: Given that impairments in cardiac autonomic modulation may contribute to a decline in functional capacity (FC) in individuals with type 2 diabetes (T2D), several studies have sought to explore the relationship between these outcomes in this population. However, to date, such studies have predominantly used maximal exercise tests to assess FC. Therefore, the aim of the present study was to examine the association between FC—measured by the distance covered in the Incremental Shuttle Walking Test (ISWT)—and heart rate variability (HRV) indices in individuals with T2D. Study Design and Methods: Cross-sectional exploratory study using baseline data from a multicenter randomized clinical trial (NCT03914924). A total of 112 individuals with T2D, aged ≥18 years, were included based on the availability of high-quality heart rate time series suitable for HRV analysis and successful completion of the ISWT. Resting heartbeats were recorded in the supine position using a heart rate monitor (Polar V800). Sixteen HRV indices were calculated using Kubios HRV software, including linear time-domain and frequency-domain parameters, as well as non-linear measures. FC was assessed by the distance covered in the ISWT, both in absolute meters and as a percentage of the predicted distance. Spearman’s correlation coefficient (ρ) was used to evaluate associations between HRV and FC, with a significance level of 5% adopted for all analyses. Results: Among the HRV measures, only the non-linear index approximate entropy showed a statistically significant—but weak—correlation with FC (ρ = - 0.18; p = 0.046). No other HRV parameters were significantly correlated with FC. Conclusion: In summary, the findings suggest no meaningful association between HRV indices and functional capacity, as assessed by the ISWT, in individuals with T2D.