ABSTRACT
BACKGROUND: Heart disease is one of the leading causes of death in Canada. Many heart disease patients are referred for cardiac rehabilitation, a multidisciplinary outpatient program often consisting of exercise training. Cardiac rehabilitation has been proven to be a successful secondary preventative measure in reducing mortality and improving overall health in heart disease patients, and its completion is important for both sexes as there is growing evidence that women benefit as much as men, if not more, with regard to mortality. It is important to note that previous studies have shown that healthy men and women respond differently to aerobic and resistance training, possibly due to hormones, body composition, autonomic and/or cardiovascular differences. However, evaluating sex differences in the efficacy of standard cardiac rehabilitation programs has not yet been fully explored with many studies investigating clinical or anthropometric data but not physiological outcomes. This systematic review aimed to investigate physiological differences in male and female heart disease patients after cardiac rehabilitation. The inclusion criteria were purposefully broad to encompass many cardiac rehabilitation scenarios, many cardiac disease states, and various program lengths and intensities with the intention of highlighting strengths and weaknesses of the current body of literature. METHODS: To conduct a synthesis without meta-analysis, a search strategy was generated to examine the relationships between heart disease patients, a supervised exercise program, physiological outcomes, and sex differences. The review was registered (Prospero: CRD42021251614) and the following databases were searched from inception to 19 December 2023: APA PsycInfo (Ovid), CINAHL Complete (EBSCOhost), Embase (Ovid), Emcare Nursing (Ovid), Medline All (Ovid; includes PubMed non-Medline), and Web of Science Core Collection. Eighty-eight studies pertaining to fitness, metabolism, body composition, respiratory function, cardiac function and C-reactive protein underwent data extraction. RESULTS AND CONCLUSIONS: Importantly, this review suggests that men and women respond similarly to a wide-range of cardiac rehabilitation programs in most physiological variables. However, many studies discussing maximal oxygen consumption, functional capacity, six-minute walk distances, and grip strength suggest that men benefit more. Further research is required to address certain limitations, such as appropriate statistical methods and type/intensity of exercise interventions.
ABSTRACT
PURPOSE: This systematic review aimed to summarize how oral contraceptives (OC) affect resting autonomic function and the autonomic response to a variety of physiological stressors. METHODS: A search strategy was created to retrieve citations investigating physiological responses comparing OC users to non-users (NOC) in response to autonomic reflex activation. RESULTS: A total of 6148 citations were identified across databases from inception to June 2, 2022, and 3870 citations were screened at the abstract level after deduplication. Then, 133 texts were assessed at full-text level, and only 40 studies met eligibility requirements. Included citations were grouped by the aspect of autonomic function assessed, including autonomic reflex (i.e., baroreflex, chemoreflex, mechanoreflex, metaboreflex, and venoarterial reflex), or indicators (i.e., heart rate variability, pulse wave velocity, and sympathetic electrodermal activity), and physiological stressors that may alter autonomic function (i.e., auditory, exercise, mental or orthostatic stress, altitude, cold pressor test, sweat test, and vasodilatory infusions). CONCLUSION: OC influence the physiological responses to chemoreflex, mechanoreflex, and metaboreflex activation. In terms of autonomic indices and physiological stressors, there are more inconsistencies within the OC literature, which may be due to estrogen dosage within the OC formulation (i.e., heart rate variability) or the intensity of the stressor (exercise intensity/duration or orthostatic stress). Further research is required to elucidate the effects of OC on these aspects of autonomic function because of the relatively small amount of available research. Furthermore, researchers should more clearly define or stratify OC use by duration, dose, and/or hormone cycling to further elucidate the effects of OC.
