Approximately 27 published articles have explored the relation between physical activity and hot flashes (a complete reference list is available from the author). Generally, these studies have evaluated Caucasian populations in the United States, Australia, and Sweden; a few have included African Americans and other racial/ethnic groups. Most studies feature observational, cross-sectional designs: one had a case-control design, and one cross-sectional study assessed physical activity prior to onset of VMS. Two observational studies followed cohorts prospectively,and 6 were randomized controlled trials. Assessment of physical activity ranged from response to a single global question to detailed recalls of activity duration, frequency, and mode. Exercise interventions in the randomized clinical trials usually featured moderate-intensity walking programs, 30 minutes a day, 3 to 5 days a week for 12 to 16 weeks. One intervention specifically evaluated increased intensity of exercise over time. Symptom assessment also varied: some studies considered frequency, severity, and/or bother as separate domains; others used a single measure or symptom frequency. No study has objectively measured VMS. Many observational studies had null findings, but 2 reported significantly increased risk of hot flashes in active women.One showed increased risk only in women who were highly active at a younger age.5 Other studies have reported protective associations: In one study, the prevalence of moderate to severe hot flashes in women in an exercise program was reported to be 21.5% compared with 43.8% in nonparticipants.A more recent study noted that highly active postmenopausal women had a lower prevalence of hot flushes compared with those who had little or no exercise (; however, women who at study initiation reported exercising every day were 49% less likely to report bothersome hot flashes during follow-up (odds ratio [OR] = 0.51; 95% confidence interval [CI] = 0.27-0.96). Over follow-up, decreases in exercise level were associated with increased VMS. The results from randomized trials are inconsistent. Two trials (only one was designed to test a specific hypothesis about VMS) reported no effect of exercise on VMS; one reported a significant increase in hot flash severity in exercisers vs controls. In contrast, 2 small, short-term trials reported statistically significant reductions in frequency and severity of VMS. A 4-month intervention enrolling 164 previously sedentary women randomized either to a walking group, yoga, or a control group showed decreased VMS in both arms relative to the control group; however, the differences were not statistically significant. Change in VMS appeared to be mediated by increases in physical fitness: participants who had the most pronounced improvement in fitness also had the most significant decrease in symptoms. In summary, although the evidence for a protective effect of exercise on VMS is minimal, the literature is limited. Most studies had insufficient power to detect any potential effect.