Physical fitness (VO2max) was highly correlated with vagal modulation (high frequency power) in healthy volunteers (r = 0.74, P = 0.0001), whereas age was not significantly related.
Cross-Sectional (n=37)
Effect estimate: r = 0.74
p-value: p=0.0001
The association between increasing age and decreasing vagal modulation is well known. However, the importance of fitness as a determinant of the decline in vagal modulation with age is not established. To test the hypothesis that decreasing vagal modulation is largely a function of declining fitness rather than increasing age, we studied a sample of healthy volunteers with a wide range of fitness levels, but a narrow age range. We assessed fitness by measuring the maximal oxygen uptake (VO2max) achieved during incremental bicycle exercise. Vagal modulation was assessed by calculating high frequency power (0.15-0.40 Hz) of the RR variability power spectrum from 24-h ECG recordings. We studied 37 healthy volunteers who were 22-44 yr old. In our sample, VO2max ranged from 25 to 70 mL.min-1.kg-1 (mean of 45 +/- 13). Age was not significantly related to high frequency power, but VO2max was highly correlated with high frequency power (r = 0.74, P = 0.0001), indicating that physical fitness is strongly associated with vagal modulation. Thus, the decline in vagal modulation often attributed to increasing age may, instead, be the result of a decline in fitness.
Goldsmith et al. (Sun,) conducted a cross-sectional in Healthy volunteers (n=37). Physical fitness (VO2max) was evaluated on Vagal modulation (high frequency power of the RR variability power spectrum) (r = 0.74, p=0.0001). Physical fitness (VO2max) was highly correlated with vagal modulation (high frequency power) in healthy volunteers (r = 0.74, P = 0.0001), whereas age was not significantly related.