title: Age-related reduction of systemic arterial compliance induces excessive myocardial oxygen consumption during sub-maximal exercise.
abstract: Reduction of systemic arterial compliance (SAC) with aging increases left ventricular afterload. The present study was designed to examine whether age-related reduction of SAC is related to excessive myocardial oxygen consumption during sub-maximal aerobic exercise. We studied elderly (60-69 years; n = 25) and senior (70-82 years; n = 25) subjects. We measured SAC immediately before the start of the ramp-fashion exercise (i.e., at the end of the 20 W warm-up exercise) and the double product (DP: systolic blood pressure x heart rate) during the ramp-fashion exercise (20-50 W). SAC was significantly lower in senior subjects (0.76 +/- 0.25 ml mmHg(-1) m(-2)) compared with elderly subjects (0.95 +/- 0.22 ml mmHg(-1) m(-2)). DP was higher in senior subjects (20 W: 14.3 +/- 3.1; 30 W: 15.9 +/- 4.2; 40 W: 17.7 +/- 4.9; 50 W: 20.6 +/- 5.6 [x 10(3) mmHg bpm]) than in elderly subjects (12.8 +/- 3.0, 14.0 +/- 3.5, 15.1 +/- 4.0, 17.1 +/- 4.3 [x 10(3) mmHg bpm]). In total subjects, SAC correlated significantly with DP (r = -0.64, r = -0.64, r = -0.64, r = -0.64). In senior subjects, SAC was related significantly to DP (r = -0.83, r = -0.78, r = -0.76, r = -0.74). In elderly subjects, SAC tended to correlate with DP although its relationships were not statistically significant (r = -0.34, r = -0.36, r = -0.33, r = -0.31). Correlation coefficients at each respective exercise intensity were significantly higher in senior subjects compared with elderly subjects. These results suggest that the age-related reduction of SAC is related to excessive myocardial oxygen consumption during sub-maximal aerobic exercise in older humans, but this relation does not become significant until the SAC reduction becomes pronounced.
authors.affiliation: Center for Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Otsuki
authors.forename: Seiji
authors.initials: S
authors.lastname: Maeda
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kesen
authors.forename: Noriko
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Takumi
authors.initials: T
authors.lastname: Tanabe
authors.forename: Jun
authors.initials: J
authors.lastname: Sugawara
authors.forename: Takashi
authors.initials: T
authors.lastname: Miyauchi
authors.forename: Shinya
authors.initials: S
authors.lastname: Kuno
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Ajisaka
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Matsuda
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001158:Arteries / Q000502:physiology*; D001794:Blood Pressure; D003187:Compliance; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*
chemical_list: D010100:Oxygen