Left ventricular response upon exercise with trained and detrained leg muscles

Biomarker Changes in Oxygen Metabolism, Acid-Base Status, and Performance after the Off-Season in Well-Trained Cyclists

During the off-season, cyclists reduce their volume and intensity of training in order to recover the body from the high workload during the competitive season. Some studies have examined the effects of the off-season on cardiovascular, metabolic, and performance levels but have not evaluated oxygen metabolism, acid-base status, and electrolytes in cyclists. Therefore, our main objective was to analyze these markers in the off-season period (8 weeks) via finger capillary blood gasometry in well-trained cyclists. We found an increase in oxygen saturation (sO2) and oxyhemoglobin (O2Hb) (p ≤ 0.05) and a decrease in fat oxidation at maximum fat oxidation (FatMax) (p ≤ 0.05). In addition, we observed a decreasing trend of VO2 in the ventilatory threshold 2 (VT2) and maximum oxygen consumption (VO2MAX) (p ≤ 0.06) after the off-season in well-trained cyclists. Negative correlations were found between the pre–post off-season differences in the VO2 at ΔFatMax and ΔHCO3− (bicarbonate ion) and between power generated at the ΔeFTP (functional power threshold) and the ΔVO2MAX with the pH (r ≥ −0.446; p ≤ 0.05). After the off-season period, well-trained cyclists had increased markers of oxygen metabolism, decreased fat oxidation at low exercise intensities, and decreased VO2 at the VT2 and VO2MAX. Relationships were found between changes in the ΔeFTP and VO2MAX with changes in the pH and between the pH and HCO3− with changes in La−.

Isolated knee extensor exercise training improves skeletal muscle vasodilation, blood flow, and functional capacity in patients with HFpEF

Patients with HFpEF experience severe exercise intolerance due in part to peripheral vascular and skeletal muscle impairments. Interventions targeting peripheral adaptations to exercise training may reverse vascular dysfunction, increase peripheral oxidative capacity, and improve functional capacity in HFpEF. Determine if 8 weeks of isolated knee extension exercise (KE) training will reverse vascular dysfunction, peripheral oxygen utilization, and exercise capacity in patients with HFpEF. Nine HFpEF patients (66 ± 5 years, 6 females) performed graded IKE exercise (5, 10, and 15 W) and maximal exercise testing (cycle ergometer) before and after IKE training (3x/week, 30 min/leg). Femoral blood flow (ultrasound) and leg vascular conductance (LVC; index of vasodilation) were measured during graded IKE exercise. Peak pulmonary oxygen uptake (V̇O2 ; Douglas bags) and cardiac output (QC ; acetylene rebreathe) were measured during graded maximal cycle exercise. IKE training improved LVC (pre: 810 ± 417, post: 1234 ± 347 ml/min/100 mmHg; p = 0.01) during 15 W IKE exercise and increased functional capacity by 13% (peak V̇O2 during cycle ergometry; pre:12.4 ± 5.2, post: 14.0 ± 6.0 ml/min/kg; p = 0.01). The improvement in peak V̇O2 was independent of changes in Q̇c (pre:12.7 ± 3.5, post: 13.2 ± 3.9 L/min; p = 0.26) and due primarily to increased a-vO2 difference (pre: 10.3 ± 1.6, post: 11.0 ± 1.7; p = 0.02). IKE training improved vasodilation and functional capacity in patients with HFpEF. Exercise interventions aimed at increasing peripheral oxidative capacity may be effective therapeutic options for HFpEF patients.

Evaluation of physical fitness and weight status among fisherwomen in relation to their occupational workload

BACKGROUND

Fisherwomen contribute significantly to the coastal economy of Eastern India; however, data about their physical fitness and weight status are scant.

OBJECTIVES

The present cross-sectional study was designed to investigate cardiorespiratory fitness and weight status of fisherwomen, which may be influenced by their occupational workload, using morphometric and anthropometric measures.

METHODS

The study was conducted among young fisherwomen (mean age 23.7 years) randomly selected from Araku, Visakhapatnam, Andhra Pradesh, and among young women who are not engaged in the fishing industry but are residents of Araku, who served as controls (mean age 21.3 years). Measurements of body composition included several anthropometric variables, while physical efficiency parameters included a physical fitness index (PFI), VO2max, total energy expenditure, and anaerobic capacity.

RESULTS

A significant difference (p<0.05) in body mass index (BMI), body surface area (BSA), body fat percentage, diastolic blood pressure, fitness index, total energy expenditure, and anaerobic power was found in fisherwomen compared with controls. Analysis of collected data showed that the majority of the fisherwomen studied have a normal range of BMI (42%), but 6% of them were found to be mildly overweight. They also showed lower fat mass (13.5 [ ± 3.87]kg) and lower waist-to-hip ratio (WHR) and conicity index. Additionally, they were found to have a moderate level of physical fitness (64.3 [ ± 1.97]%) and a higher total energy expenditure (4.92 [ ± 0.52]k.cal.min(-2)).

CONCLUSION

This study implies that physical fitness and weight status of young fisherwomen in Eastern India are influenced by their occupational workload.

Skeletal muscle signaling and the heart rate and blood pressure response to exercise: insight from heart rate pacing during exercise with a trained and a deconditioned muscle group

Endurance training lowers heart rate and blood pressure responses to exercise, but the mechanisms and consequences remain unclear. To determine the role of skeletal muscle for the cardioventilatory response to exercise, 8 healthy young men were studied before and after 5 weeks of 1-legged knee-extensor training and 2 weeks of deconditioning of the other leg (leg cast). Hemodynamics and muscle interstitial nucleotides were determined during exercise with the (1) deconditioned leg, (2) trained leg, and (3) trained leg with atrial pacing to the heart rate obtained with the deconditioned leg. Heart rate was ≈ 15 bpm lower during exercise with the trained leg (P<0.05), but stroke volume was higher (P<0.05) and cardiac output was similar. Arterial and central venous pressures, rate-pressure product, and ventilation were lower during exercise with the trained leg (P<0.05), whereas pulmonary capillary wedge pressure was similar. When heart rate was controlled by atrial pacing, stroke volume decreased (P<0.05), but cardiac output, peripheral blood flow, arterial pressures, and pulmonary capillary wedge pressure remained unchanged. Circulating [norepinephrine], [lactate] and [K(+)] were lower and interstitial [ATP] and pH were higher in the trained leg (P<0.05). The lower cardioventilatory response to exercise with the trained leg is partly coupled to a reduced signaling from skeletal muscle likely mediated by K(+), lactate, or pH, whereas the lower cardiac afterload increases stroke volume. These results demonstrate that skeletal muscle training reduces the cardioventilatory response to exercise without compromising O2 delivery, and it can therefore be used to reduce the load on the heart during physical activity.

Left ventricle haemodynamics and vaso-active hormones during graded supine exercise in healthy male subjects

Left ventricle systolic and diastolic functional parameters were measured by gated equilibrium radionuclide cardiography in 12 healthy men (age 33-51 years) at rest and during graded supine exercise. The leftventricle end-diastolic volume showed an initial small (11%) increase during low submaximal exercise [from mean 163 (SD 40) at rest to mean 181 (SD 48) ml], while left ventricle end-systolic volume decreased successively [from mean 59 (SD 19) to mean 39 (SD 21) ml] with increasing exercise. Stroke volume was therefore elevated at all exercise levels compared with rest [mean 104 (SD 23) ml], and the peak value [mean 128 (SD 33) ml] was found at the lowest exercise level, contributing 40% to the initial increase in cardiac output. Cardiac output increased from mean 6.2 (SD 1.4) at rest to mean 20.2 (SD 5.0) l.min-1 at maximum. Left ventricle peak ejection and peak filling rates increased from mean 449 (SD 89) and mean 442 (SD 85) ml.s-1 at rest to mean 996 (SD 227) and mean 1255 (SD 333) ml.s-1, respectively, at maximum. The myocardium oxygen consumption, assumed to be proportional to the sum of the stroke work and the potential energy, increased fourfold, but absolute values were twice as high as expected, indicating that extrapolation from data obtained in dog hearts (as we have done) cannot be directly applied to humans. Selected vaso-active hormones were measured at all exercise intensities. Noradrenaline (NA), adrenaline (A) and angiotensin II (AII) concentrations showed a very pronounced increase at maximal exercise compared with the preceding lower intensites, while atrial natriuretic factor (ANF) and cyclic guanosinemonophosphate (cGMP) concentrations showed a more continuous increase, and dopamine (DA) remained almost unchanged. This speaks in favour of a crucial role for NA, A and AII in preserving blood pressure at maximum exercise, while DA probably has no importance for the cardiovascular homeostasis during exercise. Increases in concentrations of ANF and cGMP were highly correlated (r = 0.86). Our data supported the opinion that there is a cardiac limitation to maximal performance connected to the cardiac pumping capacity.