Impact of marathon performance on muscles stiffness in runners over 50 years old.

Introduction: The research examines the relationship between marathon performance and muscle stiffness changes from pre to marathon in recreational runners aged 50+ years. Methods: Thirty-one male long-distance runners aged 50-73 years participated in the experiment. The muscle stiffness of quadriceps and calves was measured in two independent sessions: the day before the marathon and 30 min after the completed marathon run using a Myoton device. Results and Discussion: The 42.195-km run was completed in 4.30,05 h ± 35.12 min, which indicates an intensity of 79.3% ± 7.1% of HRmax. The long-term, low-intensity running exercise (marathon) in older recreational runners and the low level of HRmax and VO2max showed no statistically significant changes in muscle stiffness (quadriceps and calves). There was reduced muscle stiffness (p = 0.016), but only in the triceps of the calf in the dominant (left) leg. Moreover, to optimally evaluate the marathon and adequately prepare for the performance training program, we need to consider the direct and indirect analyses of the running economy, running technique, and HRmax and VO2max variables. These variables significantly affect marathon exercise.

Valsalva-derived Measures and Phenylephrine Test in Patients With Heart Failure With Reduced Ejection Fraction Receiving Comprehensive Neurohormonal Blockade Drug Therapy: A 5-year Event-free Survival Analysis.

BACKGROUND: To assess the relationships between Valsalva- and phenylephrine test-derived measures and outcome in patients with heart failure with reduced ejection fraction (HFrEF) receiving comprehensive neurohormonal blockade pharmacotherapy. METHODS AND RESULTS: Data from 56 patients with HFrEF (mean left ventricle ejection fraction of 32 ± 6%) subjected to Valsalva and phenylephrine tests were analyzed retrospectively. Baroreflex-related (Valsalva-ratio and blood pressure-RR interval slope from phase IV) and non-baroreflex-related measures (systolic blood pressure rise in phase IV [ΔSBPPHASE_IV], and pulse amplitude ratio [PAR]) were calculated from Valsalva. Short-term outcomes (HF-related hospitalization, implantable cardioverter-defibrillator shock or all-cause death within 24 months from examination) and long-term outcomes (implantable cardioverter-defibrillator shock or all-cause death within 60 months) were analyzed. The end point occurred in 16 and 18 patients, for the short- and long-term outcomes, respectively. A low ΔSBPPHASE_IV identified patients at risk in the long term, as evidenced by a low vs high ΔSBPPHASE_IV comparison (square-wave response patients assigned to low ΔSBPPHASE_IV group, P = .002), and Cox model (hazard ratio 0.91, 95% confidence interval 0.86-0.96, P < .001), and tended to identify patients at risk in the short term outcome (hazard ratio 0.95, 95% confidence interval 0.91-1.00, P = .055). There was a tendency toward a higher event-free survival in the low PAR group (low vs high PAR; hazard ratio 0.44, 95% CI 0.17-1.18, P = .104). CONCLUSIONS: Non-baroreflex-related measures obtained from Valsalva-namely, ΔSBPPHASE_IV and PAR-might carry prognostic value in patients with HFrEF receiving neurohormonal blockade pharmacotherapy.

Low ventilatory responsiveness to transient hypoxia or breath-holding predicts fast marathon performance in healthy middle-aged and older men.

The aim of this study was to test the utility of haemodynamic and autonomic variables (e.g. peripheral chemoreflex sensitivity [PCheS], blood pressure variability [BPV]) for the prediction of individual performance (marathon time and VO2max) in older men. The post-competition vasodilation and sympathetic vasomotor tone predict the marathon performance in younger men, but their prognostic relevance in older men remains unknown. The peripheral chemoreflex restrains exercise-induced vasodilation via sympathetically-mediated mechanism, what makes it a plausible candidate for the individual performance marker. 23 men aged ≥ 50 year competing in the Wroclaw Marathon underwent an evaluation of: resting haemodynamic parameters, PCheS with two methods: transient hypoxia and breath-holding test (BHT), cardiac barosensitivity, heart rate variability (HRV) and BPV, plasma renin and aldosterone, VO2max in a cardiopulmonary exercise test (CPET). All tests were conducted twice: before and after the race, except for transient hypoxia and CPET which were performed once, before the race. Fast marathon performance and high VO2max were correlated with: low ventilatory responsiveness to hypoxia (r = - 0.53, r = 0.67, respectively) and pre-race BHT (r = - 0.47, r = 0.51, respectively), (1) greater SD of beat-to-beat SBP (all p < 0.05). Fast performance was related with an enhanced pre-race vascular response to BHT (r = - 0.59, p = 0.005). The variables found by other studies to predict the marathon performance in younger men: post-competition vasodilation, sympathetic vasomotor tone (LF-BPV) and HRV were not associated with the individual performance in our population. The results suggest that PCheS (ventilatory response) predicts individual performance (marathon time and VO2max) in men aged ≥ 50 yeat. Although cause-effect relationship including the role of peripheral chemoreceptors in restraining the post-competition vasodilation via the sympathetic vasoconstrictor outflow may be hypothesized to underline these findings, the lack of correlation between individual performance and both, the post-competition vasodilation and the sympathetic vasomotor tone argues against such explanation. Vascular responsiveness to breath-holding appears to be of certain value for predicting individual performance in this population, however.

Passive bilateral leg cycling with concomitant regional circulatory occlusion for testing mechanoreflex-metaboreflex interactions in humans.

PURPOSE: The exercise pressor reflex (EPR) plays a fundamental role in physiological reactions to exercise in humans and in the pathophysiology of cardiovascular disorders. There is no "gold standard" method for EPR assessment; therefore, we propose a new protocol for testing interactions between the muscle mechanoreflex and metaboreflex (major components of EPR). METHODS: Thirty-four healthy subjects (mean age [± standard deviation] 24 ± 4 years, 22 men) were enrolled in the study. During the study, the hemodynamic and ventilatory parameters of these subjects were continuously monitored using our proposed assessment method. This assessment method consists of an initial 5-min rest period (baseline) followed by 5 min of passive cycling (PC) on an automated cycle ergometer (mechanoreceptor stimulation), after which tourniquet cuffs located bilaterally on the upper thighs are inflated for 3 min to evoke venous and arterial regional circulatory occlusion (CO) during PC (metaboreceptor stimulation). Deflation of the tourniquet cuffs is followed by a second 5 min of PC and finally by a 5-min recovery time. The control test comprises a 5-min rest period, followed by 3 min of CO only and a final 5-min recovery. RESULTS: Mean arterial pressure (MAP) and minute ventilation (MV) increased significantly during PC (MAP: from 90 ± 9.3 to 95 ± 9.7 mmHg; MV: from 11.5 ± 2.5 to 13.5 ± 2.9 L/min; both p < 0.05) and again when CO was applied (MAP: from 95 ± 9.7 to 101 ± 11.0 mmHg; MV: from 13.5 ± 2.9 to 14.8 ± 3.8 L/min; both p < 0.05). In the control test there was a slight increase in MAP during CO (from 92 ± 10.5 to 94 ± 10.0 mmHg; p < 0.05) and no changes in the ventilatory parameters. CONCLUSION: Bilateral leg passive cycling with concomitant circulatory occlusion is a new, simple and effective method for testing interactions between the mechanoreflex and metaboreflex in humans.