Male (n=21) 30 MASL 520 MASL 1080 MASL p Age (year) 31 (26-54) - - - Height (cm) 171 (168-177) - - - Weight (kg) 72 (63-79) - - - BMI (kg/m2) 24.1 (23.0-25.9) - - - SBP (mmHg) 124 (115-132) 118 (112-129) 115 (109-127)*† 0.025 DBP (mmHg) 75 (70-81) 72 (70-82) 74 (71-79) 0.918 MABP (mmHg) 90 (86-98) 89 (84-95) 87 (84-96) 0.244 PP (mmHg) 50 (42-54) 44 (38-50) 40 (34-50) 0.046 HR (bpm) 71 (69-76) 67 (61-77)* 66 (63-75)* 0.006 mRRI (ms) 848 (789-874) 899 (782-989)* 908 (798-947)* 0.006 SDRR (ms) 41 (25-60) 47 (39-57)* 43 (37-59)* 0.028 CVRR (%) 4.8 (3.1-7.0) 5.2 (4.7-6.1) 5.0 (4.0-6.2) 0.084 TP (ms2) 714 (228-1049) 737 (537-1322)* 680 (527-1280)* 0.018 VLFP (ms2) 196 (84-328) 244 (158-355) 262 (151-424) 0.156 LFP (ms2) 123 (53-419) 354 (122-538) 222 (141-459) 0.229 HFP (ms2) 208 (48-413) 222 (120-480) 219 (130-497) 0.156 nVLFP (nu) 33.1 (24.4-40.9) 34.0 (21.2-42.0) 31.7 (25.5-44.4) 0.538 nLFP (nu) 31.0 (20.6-39.6) 33.4 (26.2-44.8) 30.1 (25.4-40.7) 0.717 nHFP (nu) 27.5 (22.1-47.2) 30.2 (13.9-43.6) 28.9 (20.9-45.5) 0.867 LHR (%) 1.3 (0.6-1.8) 1.1 (0.7-3.2) 1.2 (0.5-1.9) 0.405 Female (n=28)         Age (year) 33 (26-50) - - - Height (cm) 158 (154-162)§ - - - Weight (kg) 52 (49-59)§ - - - BMI (kg/m2) 21.1 (19.5-23.3)§ - - - SBP (mmHg) 110 (103-113)§ 104 (100-113)§ 102 (100-108)§ 0.057 DBP (mmHg) 72 (67-77) 70 (66-73)§ 68 (64-72)§ 0.07 MABP (mmHg) 83 (79-90)§ 82 (79-85)§ 79 (76-84)§ 0.087 PP (mmHg) 37 (33-42)§ 35 (30-41)§ 35 (30-41)§ 0.062 HR (bpm) 76 (67-83) 70 (65-78)* 72 (65-77)* <0.001 mRRI (ms) 793 (720-891) 858 (768-923)* 836 (782-927)* <0.001 SDRR (ms) 32 (26-38) 38 (29-47)*§ 38 (31-53)* 0.004 CVRR (%) 4.1 (3.5-4.8) 4.3 (3.6-5.2)§ 4.5 (3.8-6.1)* 0.019 TP (ms2) 379 (260-553) 569 (322-784)*§ 525 (354-955)* 0.004 VLFP (ms2) 131 (63-201) 159 (114-261)* 157 (123-302)* 0.01 LFP (ms2) 109 (60-159) 138 (85-232)§ 150 (89-281) 0.069 HFP (ms2) 91 (77-229) 201 (101-314) 191 (79-309) 0.074 nVLFP (nu) 31.0 (21.0-51.5) 33.8 (24.5-44.1) 34.2 (24.1-49.7) 0.629 nLFP (nu) 26.9 (20.8-38.2) 27.5 (22.0-36.7) 26.7 (21.3-36.5) 0.779 nHFP (nu) 30.0 (23.1-47.1) 33.7 (29.1-43.7) 31.0 (21.6-46.2) 0.368 LHR (%) 0.9 (0.5-1.4) 0.8 (0.6-1.2) 1.1 (0.5-1.4) 0.507

Table 6: General characteristics, blood pressures and HRV measures of male and female subject at 3 altitudes. Values are median and interquartile range (25th to 75th percentile). *p<0.05 vs. 30 MASL; †p<0.05 vs. 520 MASL (Friedman repeated-measures analysis of variance on ranks with Student-Newman-Keuls test for post hoc pairwise comparisons). § p<0.05 vs. male subjects (Mann-Whitney rank sum test). BMI: Body mass index; HR: Heart rate; RRI: RR intervals; mRRI: Mean RRI; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; MABP: Mean arterial pressure; BT: Body temperature; bpm: Beats per minute; SDRR: Standard deviation of RRI; CVRR: Coefficient of variation of RRI; TP: Total power; VLFP: Very-low-frequency power; LFP: Low-frequency power; HFP: High-frequency power; nVLFP: Normalized VLFP; nLFP: Normalized LFP; nHFP: Normalized HFP; LHR: Low-/high-frequency power ratio; ms: Millisecond; nu: Normalized unit.