Evaluating Heart Rate Variability Time-Domain Series in Timed up and Go (TUG) and Five Times Sit-to-Stand Test (FTSST)

Heart rate variability (HRV) is a non-invasive tool widely used nowadays to assess the autonomic nervous system. It has also been used commercially as an alternative equipment to assess cardiorespiratory fitness. As there is growing interest in adopting HRV metrics in clinical settings, this pilot study aims to observe the tool’s sensitivity in two similar exercises commonly prescribed in rehabilitation treatment plans of high-risk pathological populations. 11 healthy volunteers (6 males, 5 females) aged 23.08 (std: 0.26) performed resting and two Sit-to-Stand (STS) protocols; Timed Up and Go (TUG) and Five Times Sit-to-Stand Test (FTSST) in two different sequences. ECG readings were taken using a Polar H7 heart rate sensor and Polar V800 heart rate monitor. Time-domain indices (mean HR, mean RR, SDNN, and RMSSD) were adopted in the analysis. Results confirmed that FTSST triggered decreased mean RR value (643.36 ± 63.9 ms), in comparison with the TUG protocol (666.26 ± 71.91 ms). This suggests primary indicator of increased sympathetic activity as reflected by the elevated heart rate during FTSST. Both STS protocols had significantly higher mean RR than rest (p < 0.05) in the first exercise sequence (rest-TUG-FTSST). Switching the exercise sequence between trials did not affect the R peak-to-peak interval significantly, although TUG’s reading in the second trial (rest-FTSST-TUG) showed improved cardiac performance. Continuing this study with rehabilitating individuals living a sedentary lifestyle should be carried out to further validate the findings with high-risk population.