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  • 1
    Language: English
    In: European Journal of Applied Physiology, 2012, Vol.112(6), pp.2163-2169
    Description: The aim of the study was to test the hypothesis whether different levels of sock compression (0, 10, 20, and 40 mmHg) affect erythrocyte deformability and metabolic parameters during sub-maximal and maximal running. Nine well-trained, male endurance athletes (age 22.2 ± 1.3 years, peak oxygen uptake 57.7 ± 4.5 mL min −1  kg −1 ) carried out four periods of sub-maximal running at 70% of peak oxygen uptake for 30 min followed by a ramp test until exhaustion with and without compression socks that applied different levels of pressure. Erythrocyte deformability, blood lactate, heart rate and arterial partial pressure of oxygen ( p O 2 ) were monitored before and during all of these tests. Erythrocyte deformability, heart rate, p O 2 and lactate concentration were unaffected by compression, whereas exercise itself significantly increased erythrocyte deformability. However, the increasing effects of exercise were attenuated when high compression was applied. This first evaluation of the potential effects of increasing levels of compression on erythrocyte deformability and metabolic parameters during (sub-) maximal exercise, revealed no effects whatsoever.
    Keywords: LORCA ; Rigidity ; Blood lactate ; Running
    ISSN: 1439-6319
    E-ISSN: 1439-6327
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  • 2
    In: Journal of Strength and Conditioning Research, 2013, Vol.27(5), pp.1384-1393
    Description: ABSTRACT: Wahl, P, Zinner, C, Grosskopf, C, Rossmann, R, Bloch, W, and Mester, J. Passive recovery is superior to active recovery during a high-intensity shock microcycle. J Strength Cond Res 27(5): 1384–1393, 2013—The purpose was to examine the effects of a 2-week high-intensity shock microcycle on maximal oxygen consumption and parameters of exercise performance in junior triathletes on the one hand and to evaluate the long-term effects of active (A) vs. passive (P) recovery on the other hand. Sixteen healthy junior triathletes participated in the study. For the assignment to the A or P group, the subjects were matched according to age and performance. Within 2 weeks, a total of 15 high-intensity interval sessions within three 3-day training blocks were performed. Before and 1 week after the last training session, the athletes performed a ramp test to determine V[Combining Dot Above]O2max, a time trial (TT) and a Wingate test. Furthermore, total hemoglobin (Hb) mass was determined. The results of the whole group, independent of the arrangement of recovery, were analyzed at first; second, the A and P groups were analyzed separately. Peak power output (PPO) during the ramp test and TT performance significantly increased in the whole group. The comparison of the 2 groups revealed increases for the mentioned parameters and for V[Combining Dot Above]O2 and power output at VT2 for the P group only. The V[Combining Dot Above]O2max did not change. Wingate performance increased in the A group only. The tHb mass slightly decreased. The main finding of this study was that a 14-day shock microcycle is able to improve TT performance and PPO in junior triathletes in a short period of time. Furthermore, not only the intensity but also the arrangement of interval training seems to be important as well, because only the P group showed improvements in endurance performance, despite a slightly lower training volume. These findings might be relevant for future arrangements of high-intensity interval training.
    Keywords: Triathlon -- Physiological Aspects ; Exercise -- Physiological Aspects ; Healing -- Physiological Aspects;
    ISSN: 1064-8011
    E-ISSN: 15334287
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  • 3
    Language: English
    In: Journal of Strength and Conditioning Research, Sept, 2012, Vol.26(9), p.2383(6)
    Description: The goal of the study was to evaluate and to quantify the effects of local electromyostimulation (EMS) during cycling on the cardiorespiratory system, muscle metabolism, and perceived exertion compared with cycling with no EMS. Ten healthy men (age: 24.6 [+ or -] 3.2 years, Vo2max: 54.1 [+ or -] 6.0 ml*[min.sup.-1]*[kg.sup.-1]) performed 3 incremental cycle ergometer step tests, 1 without and 2 with EMS (30 and 85 Hz) until volitional exhaustion. Lactate values and respiratory exchange ratio were significantly higher at intensities [greater than or equal to]75% peak power output (PPO) when EMS was applied. Bicarbonate concentration, base excess (BE), and [PCO.sub.2] were significantly lower when EMS was applied compared with the control at intensities [less than or equal to]75% PPO. Saliva cortisol levels increased because of the exercise but were unaffected by EMS. Furthermore, EMS showed greater effects on CK levels 24 hours postexercise than normal cycling did. Rating of perceived exertion was significantly higher at 100% PPO with EMS. No statistical differences were found for heart rate, pH, and [PO.sub.2] between the tested cycling modes. The main findings of this study are greater metabolic changes (lactate, respiratory exchange ratio, BE, HC[O.sup.-.sub.3], [PCO.sub.2]) during cycling with EMS compared with normal cycling independent of frequency, mainly visible at higher work rates. Because metabolic alterations are important for the induction of cellular signaling cascades and adaptations, these results lead to the hypothesis that applied EMS stimulations during cycling exercise might be an enhancing stimulus for skeletal muscle metabolism and related adaptations. Thus, superimposed EMS application during cycling could be beneficial to aerobic performance enhancements in athletes and in patients who cannot perform high workloads. However, the higher demand on skeletal muscles involved must be considered. KEY WORDS blood gases, creatine kinase, oxygen uptake, RPE, saliva cortisol
    Keywords: Cycling -- Physiological Aspects ; Electric Stimulation -- Research ; Metabolism -- Physiological Aspects ; Biomechanics -- Research
    ISSN: 1064-8011
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  • 4
    Language: English
    In: European Journal of Applied Physiology, 2011, Vol.111(7), pp.1405-1413
    Description: The purpose of the present study was to compare the acute hormonal response to a short-term high-intensity training (HIT) versus a high-volume endurance training (HVT) and to investigate the effects of acid–base status on cytokines involved in angiogenesis (VEGF and bFGF). Eleven subjects participated in three experimental trials. Two times subjects performed four 30-s “all-out” exercise bouts on a cycle ergometer separated by 5-min rest each, at which subjects either received bicarbonate (HIT (B)) or a placebo (HIT (P)) before the exercise. The third exercise trail consisted of a constant load exercise for 1 h at 50% peak power output (PPO). Venous blood samples were taken under resting conditions, 10, 60, and 240 min after each exercise condition to determine VEGF and bFGF serum concentrations. Capillary blood samples were taken to determine lactate concentrations and blood gas parameters. Mean pH values were significantly higher during HIT (B) compared to HIT (P). Serum VEGF concentration was significantly increased 10-min post-exercise in both HIT interventions. HVT showed no significant effects on VEGF levels. The diminished acidosis during HIT (B) had no effects on the VEGF response. There were no significant changes in bFGF in response to HIT or HVT. The present study suggests that HIT is a stimulus for exercise-induced VEGF secretion. These findings might be relevant for the arrangement of training, due to the fact that most of the training is often performed at low intensities possibly leading to an insufficient stimulus for VEGF secretion and angiogenesis.
    Keywords: Acidosis ; Hormone secretion ; Angiogenic growth factors ; High intensity intervals
    ISSN: 1439-6319
    E-ISSN: 1439-6327
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  • 5
    Language: English
    In: European Journal of Applied Physiology, 2017, Vol.117(7), pp.1517-1518
    Description: In the present reply, we would like to put forward our perspective on the points raised by Amaro-Gahete et al. The main concerns addressed by the authors deal with the stimulation modalities applied in our study, compared to the results of Miyamoto et al. (Eur J Sports Sci 16(8):1104–1110, 2016), who showed an increase in the first ventilatory threshold and VO 2peak after 16 × 30 min low-frequency neuromuscular electrical stimulation (NMES). We have to emphasize that both mentioned studies generally follow different approaches, and that the different outcomes might not only be related to stimulation modalities. Even the results of different studies, which used sole NMES is not consistent. Especially the relevance of local metabolic and ultrastructural adaptations in skeletal muscle for the translation to functional performance, that is particularly important for sport and activities, is not always investigated in these studies.
    Keywords: Elektrische Stimulation ; Training ; Sport ; Mensch ; Medicine ; Anatomy & Physiology;
    ISSN: 1439-6319
    E-ISSN: 1439-6327
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  • 6
    Language: English
    In: European Journal of Applied Physiology, 2011, Vol.111(8), pp.1641-1648
    Description: Lactate (La) and H + -ions are unequally distributed in the blood between plasma and red blood cells (RBCs). To our knowledge there is no data concerning the effects of an oral ingestion of bicarbonate (HCO 3 − ) on repeated high intensity sprint exercise and La and H + distribution between plasma and RBCs. Since an oral ingestion of HCO 3 − leads to a higher efflux of La from the working skeletal muscle to the plasma, as it was shown by previous studies, this would lead to a higher gradient of La between plasma and RBCs. Although a higher gradient leads to a higher uptake, it is even more difficult for the RBCs to take up La fast enough, due to the more stressed transport system. Since RBCs function to transport La from the working muscle and help to maintain a concentration difference between plasma and muscle, this potentially increases performance during repeated sprint exercise (e.g. 4 × 30 s). The major goal of the present investigation was to test this hypothesis. 11 male participants ingested either a solution of sodium bicarbonate (NaHCO 3 ) or placebo (CaCO 3 ). Thereafter all performed four maximal 30 s sprints with 5 min of passive rest. During the resting periods concentrations of HCO 3 − , La and H + where measured in both blood compartments (plasma and RBCs). There were no significant differences in the La-ratios between plasma and RBCs between both interventions. These results indicate that the La/H + co-transport is not affected by an oral ingestion on NaHCO 3 .
    Keywords: Hydrogen ion ; Plasma ; Red blood cells ; Sodium bicarbonate ; Wingate anaerobic test
    ISSN: 1439-6319
    E-ISSN: 1439-6327
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  • 7
    Language: English
    In: International Journal of Pharmaceutics, 15 October 2013, Vol.455(1-2), pp.159-168
    Description: Monitoring of extrusion dynamics with in-line NIR spectroscopy. Implementation of continuous manufacturing in the pharmaceutical industry requires tight process control. This study focuses on a PAT strategy for hot melt extrusion of vegetable calcium stearate (CaSt) as matrix carrier and paracetamol as active pharmaceutical ingredient (API). The extrusion was monitored using in-line near-infrared (NIR) spectroscopy. A NIR probe was located in the section between the extrusion screws and the die, using a novel design of the die channel. A chemometric model was developed based on premixes at defined concentrations and was implemented in SIPAT for real time API concentration monitoring. Subsequently, step experiments were performed for different API concentrations, screw speeds and screw designs. The predicted API concentration was in good agreement with the pre-set concentrations. The transition from one API plateau to another was a smooth curve due to the mixing behaviour of the extruder. The accuracy of the model was confirmed via offline HPLC analysis. The screw design was determined as the main influential factor on content uniformity (CU). Additionally the influence of multiple feeders had a significant impact on CU. The results demonstrate that in-line NIR measurements is a powerful tool for process development (e.g., mixing characterization), monitoring and further control strategies.
    Keywords: Hot Melt Extrusion ; Process Analytical Technology (Pat) ; Near-Infrared Spectroscopy (NIRS) ; Api Content ; Quality Control ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0378-5173
    E-ISSN: 1873-3476
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  • 8
    Language: English
    In: European journal of applied physiology, November 2014, Vol.114(11), pp.2331-9
    Description: The purpose of the present study was to evaluate the effects of superimposed electromyostimulation (E) during cycling on the acute hormonal and metabolic response, as E might be a useful tool to intensify endurance training without performing high external workloads. Thirteen subjects participated in three experimental trials each lasting 60 min in a randomized order. (1) Cycling (C), (2) cycling with superimposed E (C + E) and (3) E. Human growth hormone (hGH), testosterone and cortisol were determined before (pre) and 0', 30', 60', 240' and 24 h after each intervention. Metabolic stimuli and perturbations were characterized by lactate and blood gas analysis (pH, base excess, bicarbonate, partial pressure of oxygen, partial pressure of carbon dioxide). Furthermore, changes of the person's perceived physical state were determined. C + E caused the highest increases in cortisol and hGH, followed by C and E. Testosterone levels showed no significant differences between C + E and C. Metabolic stress was highest during C + E, followed by C and E. C + E was also the most demanding intervention from an athlete's point of view. As cortisol and hGH are known to react in an intensity dependent manner, the present study showed that superimposed E is a useful method to intensify endurance training, even when performing low to moderate external workloads. Even at lower exercise intensities, additional E may allow one to induce a high (local) stimulus. It can be speculated, that these acute hormonal increases and metabolic perturbations, might play a positive role in optimizing long-term training adaptations, similar to those of intense training protocols.
    Keywords: Electric Stimulation Therapy ; Oxygen Consumption ; Exercise -- Physiology ; Human Growth Hormone -- Blood ; Hydrocortisone -- Blood ; Muscle, Skeletal -- Physiology ; Testosterone -- Blood
    ISSN: 14396319
    E-ISSN: 1439-6327
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  • 9
    Language: English
    In: European Journal of Applied Physiology, 2014, Vol.114(11), pp.2331-2339
    Keywords: Cortisol ; HGH ; Testosterone ; Endurance training ; Perceived physical state
    ISSN: 1439-6319
    E-ISSN: 1439-6327
    Source: Springer Science & Business Media B.V.
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  • 10
    Language: English
    In: Journal of Applied Physics, 01 October 2010, Vol.108(7)
    Description: The electrical resistance of nanoporous gold prepared by dealloying is tuned by charging the surfaces of the porous structure in an electrolyte. Reversible variations in the resistance up to approximately 4% and 43% occur due to charging in the regimes of double layer charging and specific adsorption, respectively. Charging-induced variations in the electron density or of the volume cannot account for the resistance variation, indicating that this variation is primarily caused by charge-induced modifications of the charge carrier scattering at the solid-electrolyte interface. The relative resistance variation in nanoporous Au with surface charging is found to be much higher than reported for porous nanocrystalline Pt. This is due to the lesser resistance contribution from internal grain boundaries. The resistance variation in nanoporous Au is also higher than that found in thin films owing to the stronger surface scattering in the ligament structure compared to plan surfaces. We argue that the strong resistance variation in up to 43% in the regime of specific adsorption is due to the reversible formation of a chemisorbed surface layer acting as scattering centers for the charge carriers.
    Keywords: Classical And Quantum Mechanics, General Physics ; Adsorption ; Charge Carriers ; Chemisorption ; Comparative Evaluations ; Crystals ; Electric Conductivity ; Electron Density ; Electrons ; Gold ; Grain Boundaries ; Layers ; Nanostructures ; Porous Materials ; Scattering ; Solid Electrolytes ; Surfaces ; Thin Films ; Variations ; Engineering ; Physics
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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