Liu et al.  recently reported a systematic review and meta-analysis that evaluated the potential of structured exercise to alleviate the subjective frequency and severity of vasomotor symptoms (VMS). For this, the authors searched four databases in order to identify randomized controlled trials (RCTs) that evaluated the effect of structured exercise (i.e. aerobic training) on the severity and/or frequency of VMS in menopausal women. Two reviewers independently screened records for eligibility, extracted data and assessed risks of bias and evidence certainty using the Cochrane and the GRADE tools (Grading of Recommendations Assessment, Development and Evaluation). Data were pooled, when appropriate, using random-effect meta-analyses. The researchers appraised a total of twenty-one RCTs involving 2,884 participants. Compared to no-treatment (controls), exercise significantly improved severity of VMS (10 studies, standardized mean difference [SMD] = 0.25; 95% CI: 0.04 to 0.47, p = 0.02, very low certainty of evidence). The effect size was attenuated when studies with a high risk of bias were excluded (SMD = 0.11, 95% CI: -0.03 to 0.26, p = 0.13). No significant changes in vasomotor frequency were found between exercise and controls (SMD = 0.14, 95% CI: -0.03 to 0.31, p = 0.12, high certainty of evidence). The authors conclude that exercise might improve VMS severity, indicating that future rigorous randomized clinical trials (RCTs) addressing the limitations of their review are warranted to explore the optimal exercise prescription to target the severity of VMS.
During the menopausal transition, as ovarian function declines, there is an increase of the prevalence of various symptoms or complaints that affect female quality of life . Among these complaints we have VMS (hot flushes and night sweats) which can vary in frequency (up to 85%) and severity, and may persist for more than 5 years after menopause onset . VMS may be associated with adverse health outcomes including cardiovascular risk, sleep disturbances and increased fatigue [4-6]; sometimes, even interfering with work, daily activities, family relationships and social life.
Although menopausal hormone therapy (MHT) reduces VMS frequency and severity, there are still safety concerns regarding its use for specific groups of menopausal women . For this reason, there has been an increase of research exploring alternative options for the management of VMS. In this sense, structured and planned exercise seems a potential alternative for VMS management . Although a systematic review of Daley et al. , that included five RCTs, reported insufficient evidence to determine whether exercise significantly alleviates VMS, new evidence indicates that structured exercise, including aerobic and resistance interventions, and yoga, have both a positive  or limited efficacy for reducing VMS . Bearing this in mind, the authors of the commented paper  aimed at updating the evidence on the effect of structured exercise on the frequency and severity of VMS in menopausal women through a systematic review and meta-analysis. Secondarily they evaluated whether the frequency, intensity, type or time of exercise are important for the management of VMS. The authors found that in ten studies exercise significantly improved the severity of VMS (not frequency); however, the effect size was attenuated when studies with a high risk of bias were excluded. High-intensity interval training has become popular to induce better improvements in aerobic fitness, including in postmenopausal women . As the authors state, no study has evaluated the effects of high-intensity interval exercise training on VMS in menopausal women. Despite the fact that the commented study was exploratory, an interesting observation was that structured exercise significantly improved VMS severity. Various types of exercise, including resistance training, may decrease VMS frequency by inducing central β-endorphin production, which might stabilize thermoregulation through the activation of large muscle groups .
Exercise is safe and a cost-effective way to manage VMS in menopausal women, providing a wide range of health benefits. Hence, this intervention should begin during the pre- and perimenopausal stages, not only when VMS occur.
The authors appropriately expose that their meta-analysis is limited due to a high risk of bias, mainly related to the heterogeneity of the available evaluated studies; in addition to small sample sizes. Despite this, they conclude that exercise might improve VMS severity, recommending that future rigorous RCTs are needed in order to address the limitations of their meta-analysis. Optimal exercise prescription is needed, most of all the intensity of the exercise, to target the severity of VMS.
Peter Chedraui, MD, PhD
Instituto de Investigación e Innovación en Salud Integral
Universidad Católica de Santiago de Guayaquil, Guayaquil, Ecuador
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