Cardiovascular and ride time-to-exhaustion effects of an energy drink

Table 2 Comparison of resting heart rate variability parameters under energy drink and placebo conditions

Parameter	Energy drink	Placebo	p-value
RMSSD (ms)	76.1 (46.0)	83.7 (54.5)	0.33
SDNN (ms)	94.1 (34.3)	102.0 (51.9)	0.28
pNN50 (%)	38.8 (24.7)	38.8 (21.2)	1.00
LF (ms²)	1319 (756)	2295 (2593)	0.12
HF (ms²)	4047 (4569)	4235 (5317)	0.79
LF/HF ratio	0.93 (1.15)	0.91 (0.93)	0.90
SampEn	1.33 (0.37)	1.44 (0.37)	0.22

Data are presented as mean (standard deviation). RMSSD - root-mean square differences of successive R-R intervals, SDNN- standard deviation of normal-to-normal intervals, pNN50 percentage of successive NN intervals differing >50 ms, LF - low frequency, HF - high frequency, LF/HF ratio low frequency to high frequency ratio (no units), SampEn - Sample Entropy (no units).