Heart Rate Variability Alterations During Delayed-Onset Muscle Soreness Inducing Exercise – with Piezo2 Interpretation

Heart rate variability (HRV) is often modulated by pain therefore the object of the study was to assess whether delayed-onset mescle soreness (DOMS) inducing exercise bout is affected by HRV alterations already during exercise in spite of the fact that pain evolves only post-exercise. Isokinetic dynamometer was used to induce DOMS in the study on 19 young male elite handball players who were exposed to HRV measurements for the time being. The result of the study found that heart rate (HR)-dependence of time- and frequency-domain parameters could be described by an exponential-like function, while entropy showed a V-shaped function, with a minimum "turning point" seperated by descending and ascending intervals. The DOMS protocol upshifted the time- and frequency-domain parameters in the entire HR range, contrary to sample entropy values that were systematically down-shifted, indicative of an upregulated sympathetic tone. The gourp-averaged HR dependent sample entropy function showed a non-linear character under exercise, with values lower for higher DOMS than for the group with lower DOMS below the turning point HR, and vice versa above it. The differences between the respective HRV(HR)point sets representing the Low-DOMS and High-DOMS groups were quantified by a statistical method, and found to be significant at the current sample size for all the HRV parameters used. Since oxidative stress is implicated in DOMS, therefore we are the first to report that after all non-linear alterations may impact HRV in a HR dependent manner in DOMS with a Piezo2 interpretation. This finding provides further indirect evidence for an initiating neural microdamage that prevails already under DOMS-inducing exercise and the diagnostic detection of this point empowers control over avoiding further injury risk in sport and exercise activities.