@misc{DechBittmannSchaefer2020, author = {Dech, Silas and Bittmann, Frank and Schaefer, Laura}, title = {Behavior of oxygen saturation and blood filling in the venous capillary system of the biceps brachii muscle during a fatiguing isometric action}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe 618}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe 618}, number = {618}, issn = {1866-8364}, doi = {10.25932/publishup-46016}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-460166}, pages = {79 -- 87}, year = {2020}, abstract = {The objective of the study is to develop a better understanding of the capillary circulation in contracting muscles. Ten subjects were measured during a submaximal fatiguing isometric muscle action by use of the O2C spectrophotometer. In all measurements the capillary-venous oxygen saturation of hemoglobin (SvO2) decreases immediately after the start of loading and levels off into a steady state. However, two different patterns (type I and type II) emerged. They differ in the extent of deoxygenation (-10.37 ±2.59 percent points (pp) vs. -33.86 ±17.35 pp, P = .008) and the behavior of the relative hemoglobin amount (rHb). Type I reveals a positive rank correlation of SvO2 and rHb (? = 0.735, P <.001), whereas a negative rank correlation (? = -0.522, P <.001) occurred in type II, since rHb decreases until a reversal point, then increases averagely 13\% above the baseline value and levels off into a steady state. The results reveal that a homeostasis of oxygen delivery and consumption during isometric muscle actions is possible. A rough distinction in two types of regulation is suggested.}, language = {en} } @misc{DechBittmannSchaefer2021, author = {Dech, Silas and Bittmann, Frank and Schaefer, Laura}, title = {Muscle oxygenation level might trigger the regulation of capillary venous blood filling during fatiguing isometric muscle actions}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {11}, issn = {1866-8364}, doi = {10.25932/publishup-52407}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-524078}, pages = {19}, year = {2021}, abstract = {The regulation of oxygen and blood supply during isometric muscle actions is still unclear. Recently, two behavioral types of oxygen saturation (SvO2) and relative hemoglobin amount (rHb) in venous microvessels were described during a fatiguing holding isometric muscle action (HIMA) (type I: nearly parallel behavior of SvO2 and rHb; type II: partly inverse behavior). The study aimed to ascertain an explanation of these two regulative behaviors. Twelve subjects performed one fatiguing HIMA trial with each arm by weight holding at 60\% of the maximal voluntary isometric contraction (MVIC) in a 90° elbow flexion. Six subjects additionally executed one fatiguing PIMA trial by pulling on an immovable resistance with 60\% of the MVIC with each side and same position. Both regulative types mentioned were found during HIMA (I: n = 7, II: n = 17) and PIMA (I: n = 3, II: n = 9). During the fatiguing measurements, rHb decreased initially and started to increase in type II at an average SvO2-level of 58.75 ± 2.14\%. In type I, SvO2 never reached that specific value during loading. This might indicate the existence of a threshold around 59\% which seems to trigger the increase in rHb and could explain the two behavioral types. An approach is discussed to meet the apparent incompatibility of an increased capillary blood filling (rHb) despite high intramuscular pressures which were found by other research groups during isometric muscle actions.}, language = {en} } @misc{DechBittmannSchaefer2021, author = {Dech, Silas and Bittmann, Frank and Schaefer, Laura}, title = {Assessment of the Adaptive Force of Elbow Extensors in Healthy Subjects Quantified by a Novel Pneumatically Driven Measurement System with Considerations of Its Quality Criteria}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {710}, issn = {1866-8364}, doi = {10.25932/publishup-51095}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-510950}, pages = {25}, year = {2021}, abstract = {Adaptive Force (AF) reflects the capability of the neuromuscular system to adapt adequately to external forces with the intention of maintaining a position or motion. One specific approach to assessing AF is to measure force and limb position during a pneumatically applied increasing external force. Through this method, the highest (AFmax), the maximal isometric (AFisomax) and the maximal eccentric Adaptive Force (AFeccmax) can be determined. The main question of the study was whether the AFisomax is a specific and independent parameter of muscle function compared to other maximal forces. In 13 healthy subjects (9 male and 4 female), the maximal voluntary isometric contraction (pre- and post-MVIC), the three AF parameters and the MVIC with a prior concentric contraction (MVICpri-con) of the elbow extensors were measured 4 times on two days. Arithmetic mean (M) and maximal (Max) torques of all force types were analyzed. Regarding the reliability of the AF parameters between days, the mean changes were 0.31-1.98 Nm (0.61\%-5.47\%, p = 0.175-0.552), the standard errors of measurements (SEM) were 1.29-5.68 Nm (2.53\%-15.70\%) and the ICCs(3,1) = 0.896-0.996. M and Max of AFisomax, AFmax and pre-MVIC correlated highly (r = 0.85-0.98). The M and Max of AFisomax were significantly lower (6.12-14.93 Nm; p ≤ 0.001-0.009) and more variable between trials (coefficient of variation (CVs) ≥ 21.95\%) compared to those of pre-MVIC and AFmax (CVs ≤ 5.4\%). The results suggest the novel measuring procedure is suitable to reliably quantify the AF, whereby the presented measurement errors should be taken into consideration. The AFisomax seems to reflect its own strength capacity and should be detected separately. It is suggested its normalization to the MVIC or AFmax could serve as an indicator of a neuromuscular function.}, language = {en} }