The effect of paired associative stimulation with a high-intensity cortical component and a high-frequency peripheral component on heart rate and heart rate variability in healthy subjects.
P Haakana, K Holopainen, A Nätkynmäki and 3 others
PMID 37565182WHAT IT FOUND
High-intensity paired associative stimulation did not cause lasting cardiovascular stress in 17 healthy adults.
Heart rate variability changes during the session were transient and likely caused by sitting still rather than the stimulation itself. The protocol appears safe for further development.
Key findings
01Heart rate variability parameters returned to baseline immediately after stimulation, with no evidence of sympathetic activation or lasting cardiovascular effect.
02Transient increases in parasympathetic markers during the session were likely due to the participants sitting still and listening to the rhythmic sound of the device, rather than the stimulation itself.
03Sham stimulation produced similar non-significant trends, further suggesting that the active stimulation did not create profound changes in the cardiovascular system.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was conducted on only 17 healthy young adults, so the results may not apply to patients with neurological conditions, cardiovascular disease, or older adults. The lack of a robust control group for the 'sitting still' effect makes it difficult to isolate the physiological impact of the stimulation from the relaxation of the testing environment. The sample size for the sham comparison was very small (5 participants), limiting the certainty of the conclusion that the stimulation itself had no unique cardiovascular effect. Five participants had consumed coffee before the session, which can influence heart rate variability, although the authors note this effect is inconclusive in habitual drinkers.
Declared interests
The study was funded by the Sigrid Juselius Foundation, the Academy of Finland, and Helsinki University Hospital governmental subsidiary funds. No commercial conflicts of interest were declared.
The easy way to misread this
Do not interpret the transient changes in heart rate variability as a therapeutic benefit of the stimulation. The authors state these changes were likely caused by sitting still and listening to the device's sound, and they reversed immediately after the session ended.