Effects of different exercise interventions on heart rate variability and cardiovascular health factors in older adults: a systematic review

Table 1 Description of extracted HRV parameters

Variable	Units	Description	Indicator of …
SDNN	ms	Standard deviation of all NN intervals	total variability
RMSSD	ms	Square root of the mean of the sum of the squares of differences between adjacent NN intervals	short-term variability
NN50 count		Number of pairs of adjacent NN intervals differing by more than 50 ms in the entire recording	spontaneous variability
pNN50	%	NN50 count divided by the total number of all NN intervals	spontaneous variability
LF	ms²	Power in low frequency range (≤ 0.04 Hz)	sympathetic and parasympathetic, but predominantly sympathetic
HF	ms²	Power in high frequency range (0.15–0.4 Hz)	parasympathetic
LF nu		LF power in normalised units LF/(Total Power–VLF) × 100	sympathetic and parasympathetic, but predominantly sympathetic
HF nu		HF power in normalised units HF/(Total Power–VLF) × 100	parasympathetic
LF/HF		Ratio LF [ms²]/HF [ms2]	sympathetic and parasympathetic
TP	ms²	Total performance or total spectrum; corresponds to energy density between 0.00001 to 0.4 Hz	total variability
SD1	ms	Standard deviation of instantaneous beat-to-beat variability, extracted from Poincaré Plot	parasympathetic
SD2	ms	Standard deviation of the long-term variability, extracted from Poincaré Plot	sympathetic and parasympathetic

HF (nu), power in high frequency range (in normalized units); Hz, Hertz; LF (nu), power in low frequency range (in normalized units); ms, millisecond; NN50, number of pairs of adjacent NN intervals differing by more than 50 ms in the entire recording; pNN50, number of pairs of adjacent NN intervals differing by more than 50 ms in the entire recording divided by the total number of all NN intervals; RMSSD, square root of the mean of the sum of the squares of differences between adjacent NN intervals; SD1, standard deviation of instantaneous beat-to-beat variability, extracted from Poincaré Plot; SD2, standard deviation of the long-term variability, extracted from Poincaré Plot; SDNN, standard deviation of NN intervals. Modified Sammito & Böckelmann [55].

ISSN: 1861-6909