Exercise Capacity In Hypertension Research Articles

Development of a multivariate model of the six-minute walked distance to predict functional exercise capacity in hypertension

BackgroundHypertension is associated with deterioration of musculoskeletal function and functional capacity. Existing prediction models for assessment of the 6-min walk test (6MWT) do not capture the disease-related functional capacity. This study developed a multivariate prediction model of the measured 6-min walked distance (6MWDM) in hypertension and proposed target-values based on optimal therapeutic aims. MethodsSeventy-six patients (38 men, 56.1 ± 14.3 years, systolic pressure 156.7 ± 17.5 mmHg, diastolic pressure 92.9 ± 6.9 mmHg) underwent anamnesis, physical examination, and laboratory analysis. Functional capacity was assessed using the 6MWT, being the 6MWDM considered as the dependent variable. Independent variables included sex (S, coded ‘male’ = 1, ‘female’ = 0), age (A), body height (H), body mass, mean blood pressure (MBP), and physical activity (IPAQ, coded 1–5). Target-values were derived from theoretical scenarios of optimal blood pressure and physical activity, separately and combined. ResultsPatients walked 324.5 ± 10.1 m in the average of two trials 30-min apart. Pearson's correlation coefficient showed moderate-to-weak significant associations between 6MWDM and all independent variables. The final multivariate model was 6MWDP = 611.347–4.446 × MBP + 267.630 × H – 1.511 × A + IPAQcode + Scode (adjusted R2 = 0.680, SE of bias = 6.3 m), suggesting that clinical, anthropometric, and hemodynamic information determines functional capacity. Predicted values yielded a group-average of 325 ± 87 m. Target-values under the optimal scenario resulted in 420 ± 60 m. ConclusionsSex (men), higher body height, higher physical activity, lower mean blood pressure, and lower age are independently correlated with higher 6MWDM in patients with hypertension. Target-values can be estimated for therapeutic aims related to hemodynamics and lifestyle.

Phosphodiesterase type 5 inhibition reverses impaired forearm exercise-induced vasodilatation in hypertensive patients

Established hypertension is characterized by increased peripheral vascular resistance and endothelial dysfunction, features that may underlie the reduced exercise-induced vasodilatation seen in hypertensive patients. Sildenafil citrate is a phosphodiesterase type 5 (PDE5) inhibitor used clinically for the treatment of male erectile dysfunction. Its vasodilating properties are due to the inhibition of cyclic guanosine monophosphate (cGMP) breakdown and prolongation of the signalling actions of the nitric oxide (NO)-cGMP pathway in vascular smooth muscle cells. Sildenafil has beneficial effects on endothelial function and exercise tolerance in congestive heart failure and pulmonary hypertension, and we hypothesized that it would improve exercise-induced vasodilatation in hypertensive patients. Ten hypertensive patients and ten matched normotensive subjects were studied in a three-way, randomized, single-blind and placebo-controlled study. On each study day, forearm blood flow (FBF) responses to handgrip exercise were assessed before and after intra-arterial (brachial) infusion of sildenafil, verapamil (a control, cGMP-independent vasodilator), and saline (placebo). Preinfusion exercise-induced vasodilatation was significantly reduced in hypertensive patients compared to normotensive controls. Sildenafil and verapamil infusions both caused a similar increase in baseline FBF. However, while verapamil did not affect the vasodilator response to handgrip exercise in either group, sildenafil substantially enhanced this response in hypertensive patients, but not in normotensive subjects. Our data suggest that sildenafil, through an increase in cGMP levels in the vasculature, substantially and selectively improves the vasodilator response to handgrip exercise in hypertensive patients. These findings represent an essential first step in support of further studies exploring the potentially beneficial effects of PDE5 inhibition on impaired exercise capacity in hypertension.

Muscle Fibre Types, Ubiquinone Content and Exercise Capacity in Hypertension and Effort Angina

The composition of skeletal muscle fibre expressed as a percentage of slow twitch (ST), type I or "red" and fast twitch (FT), type II or "white" were determined in patients with hypertension (HT) or with severe ischaemic heart disease (IHD) and compared to age matched controls. Similarly, exercise capacity expressed as the cycle intensity eliciting a blood lactate concentration corresponding to 2.0 mmol x 1-1 were compared with healthy controls. Both patient groups had a higher percentage of FT fibres with relatively lower exercise capacities than their controls. The exercise capacities were reduced even when the relationship of decreased capacity with the percentage of increased FT was considered. There was an increase IHD but not in HT in patients with fibre subgroup FTc, which most probably reflected fibre trauma. Both patient groups were low in the skeletal muscle mitochondrial electron carrier and unspecific antioxidant ubiquinone, coenzyme Q10 or CoQ10. Patients with IHD but not HT showed, however, a faster fall in the ratio CoQ10 over ST% the higher the percentage value of ST. The ratio reflects the antioxidant activity related to CoQ10 in the fibre hosting most of the oxidative metabolism. A low ratio indicates a risk of metabolic lesion and cell trauma. This could explain fibre plasticity and offer an alternative cause to heredity in elucidating in deviating muscle fibre composition in patients with HT and IHD.