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Influence of age on arterial stiffness responses following a short period of sitting in healthy males

      Background: Age-related increases in arterial stiffness including carotid-femoral pulse wave velocity (cf-PWV), aortic wave reflection via augmentation index (AIx) and reflection magnitude (RM) have been associated with future cardiovascular event risk. Chronic or prolonged inactivity has been reported to exacerbate the age-related increases in arterial stiffness. However, little is known about the impact of a short, period of inactivity on arterial stiffness with age potentially an influencing factor. The aim of this study was to examine the effect of age on the acute, arterial stiffness responses following a short period of sitting in healthy males.
      Methods: Twenty-two young (27.1±7.3 yrs, 177.4±5.4 cm, 82.2±10.2 kg, 26.1±3.1 kg.m-2) and twenty-two older (68.8±5.3 yrs, 174.6±7.6 cm, 77.7±7.0 kg, 25.6±3.0 kg.m-2) males volunteered. Supine, resting measures of cf-PWV, AIx corrected to a heart rate of 75 (AIx75) and RM were obtained prior to (baseline), and 20-, 40- and 60-minutes following a short period of sitting (24-30 minutes). Heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial (MAP) blood pressure were recorded throughout the sitting period. Significant (p<0.05) differences over time and between groups were examined by 2-way ANOVA and post-hoc, pairwise comparisons with Bonferroni correction.
      Results: During the short period of sitting, lower HR (53.9±8.0 vs. 64.6±7.7 bpm, p<0.001) and greater peripheral SBP (131.2±13.1 vs. 118.8±9.6 mmHg, p<0.001), DBP (79.9±8.7 vs. 74.7±6.4 mmHg, p=0.027) and MAP (97.0±9.2 vs. 89.4±7.0 mmHg, p=0.003) were observed in the older compared to the young group. The older group exhibited significantly greater resting cf-PWV (9.0±1.4 vs. 7.3±0.9 m.s-1, p<0.001), AIx75 (12.6±9.2 vs. 4.0±14.0 %, p=0.011) and RM (73.6±14.0 vs. 59.0±12.4 %, p<0.001), and lower HR (48.9±6.4 vs. 55.0±7.7 bpm, p=0.002) compared to the young group. Compared to baseline, cf-PWV was significantly increased at 60-minutes after the sitting period (p<0.05) with the change being similar between groups (p=0.792). In contrast, AIx75 and RM were significantly decreased at 40- and 60-minutes after sitting (p<0.05) with the change being similar between groups (p>0.05).
      Discussion: A short period of sitting resulted in a significant increase in central arterial stiffness (cf-PWV) and a concurrent decrease in peripheral arterial stiffness (AIx75 and RM) with these responses being unaffected by age in healthy males. The current results extend previous work that sitting, even for a short period, may progressively contribute to changes in central and peripheral arterial stiffness and future cardiovascular event risk.
      "My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract."