Cardiovascular disease (CVD) is the number one cause of death in the developed world, accounting for 30% of deaths. Individuals with Spinal Cord Injuries (SCI) are at higher risk, with 40% of deaths being attributable to CVD. With a special population such as SCI’s that cannot gain the same cardiovascular benefits of exercise that able-bodied (AB) individuals can, chronic passive heat therapy (CHT) becomes a possible substitute. A determining risk factor of cardiovascular disease is increased arterial stiffness, and pulse wave velocity (PWV) is a proven method for assessing arterial stiffness. PURPOSE: To examine the effect of 8 weeks of CHT on aortic and leg PWV in both AB and SCI subjects. METHODS: Seven subjects (2 male AB, 4 female AB, 1 male SCI; ages 22 ± 1 yrs, BMI 22 ± 1 m2/kg), completed 8 weeks of CHT, consisting of 4-5 sessions a week (36 sessions total) in a 40.5°C hot tub to maintain rectal temperature between 38.5-39.0°C for 60 min. At 0 and 8 weeks, PWV was assessed using applanation tonometry, with probes placed over the common carotid and common femoral arteries (C-F, aortic) and common femoral and posterior tibial arteries (F-A, leg). The measured distance between the two probes was divided by the time delay between pulses to give the PWV. Data are mean ± S.E. cm/sec. RESULTS: Following 8 weeks of CHT, C-F PWV decreased from 687 to 652 cm/s (p=0.12) in AB subjects and from 773 to 720 cm/sec in the SCI subject, indicating a trend towards reduced aortic arterial stiffness. There was no change in F-A PWV’s in AB subjects (949 to 976 cm/sec, p=0.47), but leg PWV substantially improved in the SCI subject from 1,034 to 806 cm/sec. CONCLUSION: Based on our preliminary data, CHT reduces aortic arterial stiffness in both AB and SCI subjects, indicating reduced cardiovascular risk. Of note, the greatest improvement observed was that of F-A PWV in the SCI subject. As such, CHT shows great promise for improving cardiovascular health in individuals with SCI, and may provide a novel therapeutic approach for other special populations to reduce cardiovascular disease risk, such as the obese and diabetics.

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