The aim of the present study was to compare and analyse the relationships between pulmonary oxygen uptake and vastus lateralis (VL) muscle oxygen desaturation kinetics measured bilaterally with Moxy NIRS sensors in trained endurance athletes. To this end, 18 trained athletes (age: 42.4 ± 7.2 years, height: 1.837 ± 0.053 m, body mass: 82.4 ± 5.7 kg) visited the laboratory on two consecutive days. On the first day, an incremental test was performed to determine the power values for the gas exchange threshold, the ventilatory threshold (VT), and V̇O2max levels from pulmonary ventilation. On the second day, the athletes performed a constant work rate (CWR) test at the power corresponding to the VT. During the CWR test, the pulmonary ventilation characteristics, left and right VL muscle O2 desaturation (DeSmO2), and pedalling power were continuously recorded, and the average signal of both legs’ DeSmO2 was computed. Statistical significance was set at p ≤ 0.05. The relative response amplitudes of the primary and slow components of VL desaturation and pulmonary oxygen uptake kinetics did not differ, and the primary amplitude of muscle desaturation kinetics was strongly associated with the initial response rate of oxygen uptake. Compared with pulmonary O2 kinetics, the primary response time of the muscle desaturation kinetics was shorter, and the slow component started earlier. There was good agreement between the time delays of the slow components describing global and local metabolic processes. Nevertheless, there was a low level of agreement between contralateral desaturation kinetic variables. The averaged DeSmO2 signal of the two sides of the body represented the oxygen kinetics more precisely than the right- or left-leg signals separately.
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Purpose of the present study was to examine the changes in the pedalling kinetics and in the ground reaction forces as a measure of the cycling stability during an incremental cycling exercise. Furthermore, we compared the effectiveness of the pedalling technique and postural stability between the high and low Functional Movement Screen score (FMSTM) cyclists and analysed the relationships between the cycling specific postural stability, pedalling kinetics and cyclists FMSTM test scores. 31 competitive cyclists (18.5±2.1y; 1.81±0.06m; 73.7±7.5kg) were categorized based on the (FMSTM) test results in a low (LS, n=19; FMS≤14) and a high (HS, n=12; FMS>14) score group. The pedalling effectiveness and absolute symmetry indexes, as well the ground reaction force (GRF) were measured during incremental cycling exercise. Cycling specific postural stability was expressed as the body mass corrected standard deviation of 3 linear and 3 angular GRF components during a 30sec cycling at four power levels. We found that during incremental cycling exercise the pedalling effectiveness, smoothness and cyclist’s swaying in all three planes increased according to the combined effect of the workload and fatigue. Cyclists with high FMSTM score showed a lower bilateral pedalling asymmetry and a greater cycling specific postural stability, but showed no differences in the pedalling effectiveness and smoothness compared with the LS cyclists. Cyclist’s FMSTM score were moderately related with the stability components acting along the horizontal plane. The pedalling effectiveness, smoothness and bilateral asymmetry were inversely related to the components acting perpendicularly to the horizontal plane.
A simple and fast method for the analysis of lactate from a single drop of blood was developed. The finger-prick whole blood sample (10 µL) was diluted (1:20) with a 7% (w/v) solution of [tris(hydroxymethyl)methylamino] propanesulfonic acid and applied to a blood plasma separation device. The device accommodates a membrane sandwich composed of an asymmetric polysulfone membrane and a supporting textile membrane that allows the collection of blood plasma into a narrow glass capillary in less than 20 s. Separated and simultaneously diluted blood plasma was directly injected into a capillary electrophoresis instrument with a contactless conductivity detector (CE-C4D) and analyzed in less than one minute. A separation electrolyte consisted of 10 mmol/L l-histidine, 15 mmol/L dl-glutamic acid, and 30 µmol/L cetyltrimethylammonium bromide. The whole procedure starting from the finger-prick sampling until the CE-C4D analysis was finished, took less than 5 min and was suitable for monitoring lactate increase in blood plasma during incremental cycling exercise. The observed lactate increase during the experiments measured by the developed CE-C4D method correlated well with the results from a hand-held lactate analyzer (R = 0.9882). The advantage of the developed CE method is the speed, significant savings per analysis, and the possibility to analyze other compounds from blood plasma.
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