Table 3.

MSNA and cardiovascular variables at baseline and during lower body negative pressure (LBNP)

			Stimulus		2-way RM ANOVA P-value

Variable	Group	Baseline	LBNP −15	LBNP −30	Group	Time point	Interaction
MSNA, bursts·min⁻¹	YG (n=12)	10 ± 1	15 ± 2	22 ± 3	0.004	<0.001	0.237
	MA/O (n=10)	25 ± 4	30 ± 4	33 ± 5	0.004	<0.001	0.237

MSNA, bursts·100hb⁻¹	YG (n=12)	17 ± 2	24 ± 3	32 ± 5	<0.001	<0.001	0.280
	MA/O (n=10)	45 ± 7	53 ± 7	57 ± 8	<0.001	<0.001	0.280

MSNA, AU·min⁻¹	YG (n=12)	490 ± 66	780 ± 101	1317 ± 293	0.021	<0.001	0.655
	MA/O (n=10)	1180 ± 221	1611 ± 233	1871 ± 408	0.021	<0.001	0.655

Norepinephrine, pg·mL⁻¹	YG (n=12)	211 ± 34	221 ± 20	306 ± 37	<0.001	<0.001	0.003
	MA/O (n=13)	298 ± 34	552 ± 47^*^†	598 ± 68^*^†	<0.001	<0.001	0.003

Systolic BP, mmHg	YG (n=15)	113 ± 2	112 ± 3	112 ± 3	0.520	<0.001	0.135
	MA/O (n=14)	117 ± 3	117 ± 4	112 ± 4	0.520	<0.001	0.135

Diastolic BP, mmHg	YG (n=15)	68 ± 1	68 ± 1	71 ± 1^*	0.165	0.272	0.049
	MA/O (n=14)	73 ± 2	73 ± 3	72 ± 3	0.165	0.272	0.049

Mean BP, mmHg	YG (n=15)	83 ± 1	83 ± 2	84 ± 2	0.248	0.722	0.038
	MA/O (n=14)	88 ± 2	88 ± 3	86 ± 3	0.248	0.722	0.038

Heart rate, beats·min⁻¹	YG (n=15)	59 ± 2	61 ± 2	68 ± 3^#	0.028	<0.001	0.021
	MA/O (n=14)	54 ± 2	55 ± 3	58 ± 3^#†	0.028	<0.001	0.021

Values are means ± SE. YG, young adults; MA/O, middle-age/older adults; MSNA, muscle sympathetic nerve activity; AU, arbitrary units; BP, arterial blood pressure;

P<0.05 vs. baseline,

P<0.05 vs. baseline and LBNP −15mmHg;

^†

P<0.05 vs. YG; Holm-Sidak post hoc did not detect significant differences between YG and MA/O in mean BP during LBNP despite 2-way RM ANOVA significant interaction.