We performed a meta-regression analysis of 73 studies that examined whether cardiorespiratory fitness mitigates cardiovascular responses during and after acute laboratory stress in humans. The cumulative evidence indicates that fitness is related to slightly greater reactivity, but better recovery. However, effects varied according to several study features and were smallest in the better controlled studies. Fitness did not mitigate integrated stress responses such as heart rate and blood pressure, which were the focus of most of the studies we reviewed. Nonetheless, potentially important areas, particularly hemodynamic and vascular responses, have been understudied. Women, racial/ethnic groups, and cardiovascular patients were underrepresented. Randomized controlled trials, including naturalistic studies of real-life responses, are needed to clarify whether a change in fitness alters putative stress mechanisms linked with cardiovascular health.

SummaryBackgroundGeneral practitioners are usually the first health professionals to be contacted by people with early signs of psychosis. We aimed to assess whether increased liaison between primary and secondary care improves the clinical effectiveness and cost-effectiveness of detection of people with, or at high risk of developing, a first psychotic illness.MethodsOur Liaison and Education in General Practices (LEGs) study was a cluster-randomised controlled trial of primary care practices (clusters) in Cambridgeshire and Peterborough, UK. Consenting practices were randomly allocated (1:1) to a 2 year low-intensity intervention (a postal campaign, consisting of biannual guidelines to help identify and refer individuals with early signs of psychosis) or a high-intensity intervention, which additionally included a specialist mental health professional who liaised with every practice and a theory-based educational package. Practices were not masked to group allocation. Practices that did not consent to be randomly assigned comprised a practice-as-usual (PAU) group. The primary outcome was number of referrals of patients at high risk of developing psychosis to the early intervention service per practice site. New referrals were assessed clinically and stratified into those who met criteria for high risk or first-episode psychotic illness (FEP; together: psychosis true positives), and those who did not fulfil such criteria for psychosis (false positives). Referrals from PAU practices were also analysed. We assessed cost-effectiveness with decision analytic modelling in terms of the incremental cost per additional true positive identified. The trial is registered at the ISRCTN registry, number ISRCTN70185866.FindingsBetween Dec 22, 2009, and Sept 7, 2010, 54 of 104 eligible practices provided consent and between Feb 16, 2010, and Feb 11, 2011, these practices were randomly allocated to interventions (28 to low intensity and 26 to high intensity); the remaining 50 practices comprised the PAU group. Two high-intensity practices were excluded from the analysis. In the 2 year intervention period, high-intensity practices referred more FEP cases than did low-intensity practices (mean 1·25 [SD 1·2] for high intensity vs 0·7 [0·9] for low intensity; incidence rate ratio [IRR] 1·9, 95% CI 1·05–3·4, p=0·04), although the difference was not statistically significant for individuals at high risk of psychosis (0·9 [1·0] vs 0·5 [1·0]; 2·2, 0·9–5·1, p=0·08). For high risk and FEP combined, high-intensity practices referred both more true-positive (2·2 [1·7] vs 1·1 [1·7]; 2·0, 1·1–3·6, p=0·02) and false-positive (2·3 [2·4] vs 0·9 [1·2]; 2·6, 1·3–5·0, p=0·005) cases. Referral patterns did not differ between low-intensity and PAU practices. Total cost per true-positive referral in the 2 year follow-up was £26 785 in high-intensity practices, £27 840 in low-intensity practices, and £30 007 in PAU practices.InterpretationThis intensive intervention to improve liaison between primary and secondary care for people with early signs of p...

We examined hemodynamic and autonomic components of blood pressure responses during active and passive stressor tasks in a sample of young, normotensive men and women who were physically active but differed on fitness (i.e., VO2peak). During the hand cold pressor, increases in systolic blood pressure were inversely related to fitness among women but not men. Regardless of gender, fitter participants had a greater increase in cardiac pace during mental arithmetic, coherent with a decreased cardiac-vagal component of heart rate variability, and a greater compensatory reduction in stroke volume. Fitness was otherwise unrelated to changes in cardiac output and vascular resistance during the stressor tasks. Our findings suggest that cardiorespiratory fitness augments the cardiac-vagal withdrawal that is characteristic of mental arithmetic. The blunted systolic blood pressure response to the hand cold pressor among fitter women suggests that cardiorespiratory fitness should be considered as a covariate in studies that examine the hand cold pressor as a predictor of future hypertension among women.

The findings confirm our previous report that fitness blunts systolic blood pressure response during the hand cold pressor in young women. They also suggest that future studies of fitness and blood pressure reactivity during stress should focus on the regulation of vascular responses and their recovery after stress. Weaker effects of VO2peak after mental arithmetic in the positive history group indicate that the level of fitness required to modify recovery from mental stress among black American women may differ according to parental history of hypertension.