ORIGINAL ARTICLE Acute effects of warm footbath on arterial stiffness in healthy young and older women Qingfeng Hu • Weili Zhu • Yili Zhu • Lu Zheng • Richard L. Hughson Received: 25 February 2011 / Accepted: 28 June 2011 / Published online: 21 July 2011 Ó Springer-Verlag 2011 Abstract Acute systemic thermal therapy can improve arterial stiffness in both animals and humans. We examined and compared the effects of acute local thermal therapy (footbath) on an indicator of human arterial stiffness, car- dio-ankle vascular index (CAVI), in 16 healthy young (29.4 ± 0.4 years) and 16 older (59.8 ± 1.7 years) women. Measurements were made at baseline (BL) and at 0 and 30 min after footbath in footbath trial, and at corresponding time points without footbath in control trial. In the footbath trial, subjects immersed their lower legs and feet in water for 30 min, with water temperature ranging from 41 to 43°C. The results showed that footbath elicited significant reductions in CAVI at 0 min compared to the same trial’s baseline in both young and older groups (0.55 ± 0.07, P = 0.01 for young; 0.42 ± 0.15, P = 0.03 for older, respectively) with no changes found in the control trials. The percentage of CAVI change at 0 min was significantly greater in young women (91.9 ± 1.1%) compared to older women (96.5 ± 1.8%, P \ 0.05). This study indicated that acute warm footbath results in transient improvement of systemic arterial stiffness in both healthy young and older women. Despite similar intervention, the percentage response of arterial stiffness to footbath was attenuated in older women. Keywords Aging Á Warm footbath Á Arterial stiffness Introduction Cardiovascular diseases have become the leading cause of death among Chinese women (Cao et al. 2008; He et al. 2005). Arterial stiffness, an independent predictor of adverse cardiovascular events and mortality (Lebrun et al. 2002), increases with aging in sedentary healthy females (Nagai et al. 1999; Tanaka et al. 1998). Interventions to improve arterial stiffness may help to maintain cardiovas- cular health and prevent cardiovascular diseases in aged females. Thermal therapy (exposure of body to heat) is widely practiced in many cultures. Evidence has demonstrated that systemic thermal therapy, such as bathing and sauna, can benefit human cardiovascular health in terms of cardiac function (Kisanuki et al. 2007; Tei 2001), blood pressure (Boone et al. 1999; Miwa et al. 1994; Nagasawa et al. 2001; Tei et al. 1995) and endothelial function (Kihara et al. 2002). Thermal therapy might also improve arterial stiffness in humans. First, raising body temperature resulted in a sig- nificant increase in endothelial nitric oxide synthase (eNOS) activity (Harris et al. 2003). Since eNOS generates nitric oxide (NO) in blood vessels and endothelium-derived NO regulates arterial stiffness (Kinlay et al. 2001; Stewart et al. 2003; Wilkinson et al. 2004), increased eNOS activity induced by thermal therapy might increase the bioavail- ability of NO, and hence might decrease the arterial stiff- ness. Second, thermal therapy increases the blood flow (Green et al. 2010; Imamura et al. 2001) resulting in increased shear stress that may modulate arterial stiffness (Kinlay et al. 2001). Finally, previous investigation in Communicated by Keith Phillip George. Q. Hu Á W. Zhu (&) Á Y. Zhu Á L. Zheng Capital University of Physical Education and Sports, 11 Bei San Huan Xi Road, Beijing 100191, People’s Republic of China e-mail: zzhuweili@gmail.com W. Zhu Á R. L. Hughson Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada 123 Eur J Appl Physiol (2012) 112:1261–1268 DOI 10.1007/s00421-011-2066-1