296 Exp Physiol 93.2 pp 296–302 Experimental Physiology Resistance training in men is associated with increased arterial stiffness and blood pressure but does not adversely affect endothelial function as measured by arterial reactivity to the cold pressor test Hiroshi Kawano 1,2 , Michiya Tanimoto 1 , Kenta Yamamoto 2 , Kiyoshi Sanada 2 , Yuko Gando 1,2 , Izumi Tabata 1 , Mitsuru Higuchi 2 and Motohiko Miyachi 1 1 National Institute of Health and Nutrition Program for Health Promotion, 1-23-1 Toyama, Shinjuku 162-8636, Japan 2 Wasada University, 2-579-15 Mikajima, Tokorazawa, Saitama, Japan Resistance training is a popular mode of exercise, but may result in stiffening of the central arteries. Changes in carotid artery diameter were determined using the cold pressor test (CPT), which results in production of nitric oxide via sympathetic activation and is one of the novel methods available for assessing endothelial function in the carotid artery. To investigate the effect of resistance training on endothelial function, we designed a cross-sectional study of carotid arterial vasoreactivity to CPT in men participating in regular resistance training with increased carotid arterial stiffness compared with age-matched control subjects. Twelve resistance-trained middle-aged men (age 38.7 ± 1.7 years) and 17 age-matched control subjects (age 36.8 ± 1.2 years) were studied. The direction and magnitude of changes in carotid artery diameter were measured by B-mode ultrasonography during sympathetic stress induced by submersion of the foot in ice slush for 90 s. Carotid arterial β-stiffness index, and systolic and mean arterial blood pressure were higher (7.7 ± 0.7 versus 6.0 ± 0.4 arbitrary units, 116 ± 2 versus 131 ± 4 mmHg and 86 ± 2 versus 95 ± 2 mmHg, respectively, all P < 0.05) in the resistance training group compared with control subjects. There were, however, no significant differences in the amount or percentage change in carotid artery diameter in CPT between the two groups (resistance training group, 0.33 ± 0.07 mm and 5.2 ± 1.1%; control group, 0.37 ± 0.06 mm and 5.8 ± 0.9%, respectively). These findings suggest that while carotid arterial stiffening and higher blood pressure are observed in regular resistance-trained men, these are not associated with abnormalities in carotid arterial vasoreactivity to sympathetic stimulus, which implies intact endothelial function. (Received 9 August 2007; accepted after revision 27 September 2007; first published online 2 October 2007) Corresponding author M. Miyachi: National Institute of Health and Nutrition Program for Health Promotion, 1–23-1 Toyama, Shinjuku 162–8636, Japan. Email: miyachi@nih.go.jp Resistance training is a popular form of exercise, and has become an integral component of exercise recommendations endorsed by a number of national health organizations (American College of Sports Medicine Position Stand, 1998; Pollock et al. 2000). Resistance training has favourable effects on the musculoskeletal system, thereby contributing to maintenance of functional capacity and prevention of sarcopenia and osteoporosis. In contrast, resistance training may be associated with reduction of compliance and increases in arterial stiffness in the central elastic artery (carotid artery; Bertovic et al. 1999; Miyachi et al. 2003, 2004; Cortez-Cooper et al. 2005; Kawano et al. 2006). Increased arterial stiffness and reduced arterial compliance may be associated with endothelial dysfunction (Lind et al. 1999; Cheung et al. 2002; Nakamura et al. 2004). Indeed, impaired endothelial function and arterial stiffening are induced with advancing age and in the presence of cardiovascular diseases (Zeiher et al. 1989; O’Rourke, 1990; Taddei et al. 1995; Tanaka et al. 2000; Najjar et al. 2005). Therefore, DOI: 10.1113/expphysiol.2007.039867 C  2007 The Authors. Journal compilation C  2007 The Physiological Society