56687
2022
2022
eng
1
10
10
postprint
Universitätsverlag Potsdam
Potsdam
1
2022-11-16
2022-11-16
--
Muscle oxygenation and time to task failure of submaximal holding and pulling isometric muscle actions and influence of intermittent voluntary muscle twitches
Background
Isometric muscle actions can be performed either by initiating the action, e.g., pulling on an immovable resistance (PIMA), or by reacting to an external load, e.g., holding a weight (HIMA). In the present study, it was mainly examined if these modalities could be differentiated by oxygenation variables as well as by time to task failure (TTF). Furthermore, it was analyzed if variables are changed by intermittent voluntary muscle twitches during weight holding (Twitch). It was assumed that twitches during a weight holding task change the character of the isometric muscle action from reacting (≙ HIMA) to acting (≙ PIMA).
Methods
Twelve subjects (two drop outs) randomly performed two tasks (HIMA vs. PIMA or HIMA vs. Twitch, n = 5 each) with the elbow flexors at 60% of maximal torque maintained until muscle failure with each arm. Local capillary venous oxygen saturation (SvO2) and relative hemoglobin amount (rHb) were measured by light spectrometry.
Results
Within subjects, no significant differences were found between tasks regarding the behavior of SvO2 and rHb, the slope and extent of deoxygenation (max. SvO2 decrease), SvO2 level at global rHb minimum, and time to SvO2 steady states. The TTF was significantly longer during Twitch and PIMA (incl. Twitch) compared to HIMA (p = 0.043 and 0.047, respectively). There was no substantial correlation between TTF and maximal deoxygenation independently of the task (r = − 0.13).
Conclusions
HIMA and PIMA seem to have a similar microvascular oxygen and blood supply. The supply might be sufficient, which is expressed by homeostatic steady states of SvO2 in all trials and increases in rHb in most of the trials. Intermittent voluntary muscle twitches might not serve as a further support but extend the TTF. A changed neuromuscular control is discussed as possible explanation.
Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
10.25932/publishup-56687
urn:nbn:de:kobv:517-opus4-566878
1866-8364
Version of record
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/56686">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
Dech, Silas
false
true
CC-BY - Namensnennung 4.0 International
Silas Dech
Frank N. Bittmann
Laura V. Schaefer
Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
798
eng
uncontrolled
Oxygen saturation
eng
uncontrolled
Microvascular blood filling
eng
uncontrolled
Isometric contraction
eng
uncontrolled
Isometric muscle action
eng
uncontrolled
Holding isometric muscle action
eng
uncontrolled
Pulling isometric muscle action
eng
uncontrolled
Pushing isometric muscle action
eng
uncontrolled
Time to task failure
eng
uncontrolled
Muscle twitch
Medizin und Gesundheit
open_access
Strukturbereich Kognitionswissenschaften
Referiert
Green Open-Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/56687/phr_798.pdf
40208
2017
2017
eng
13
postprint
1
--
2017-10-18
--
Are there two forms of isometric muscle action?
Background
In isometric muscle function, there are subjectively two different modes of performance: one can either hold isometrically – thus resist an impacting force – or push isometrically – therefore work against a stable resistance. The purpose of this study is to investigate whether or not two different isometric muscle actions – the holding vs. pushing one (HIMA vs PIMA) – can be distinguished by objective parameters.
Methods
Ten subjects performed two different measuring modes at 80% of MVC realized by a special pneumatic system. During HIMA the subject had to resist the defined impacting force of the pneumatic system in an isometric position, whereby the force of the cylinder works in direction of elbow flexion against the subject. During PIMA the subject worked isometrically in direction of elbow extension against a stable position of the system. The signals of pressure, force, acceleration and mechanomyography/-tendography (MMG/MTG) of the elbow extensor (MMGtri/MTGtri) and the abdominal muscle (MMGobl) were recorded and evaluated concerning the duration of maintaining the force level (force endurance) and the characteristics of MMG-/MTG-signals. Statistical group differences comparing HIMA vs. PIMA were estimated using SPSS.
Results
Significant differences between HIMA and PIMA were especially apparent regarding the force endurance: During HIMA the subjects showed a decisively shorter time of stable isometric position (19 ± 8 s) in comparison with PIMA (41 ± 24 s; p = .005). In addition, during PIMA the longest isometric plateau amounted to 59.4% of the overall duration time of isometric measuring, during HIMA it lasted 31.6% (p = .000). The frequency of MMG/MTG did not show significant differences. The power in the frequency ranges of 8–15 Hz and 10–29 Hz was significantly higher in the MTGtri performing HIMA compared to PIMA (but not for the MMGs). The amplitude of MMG/MTG did not show any significant difference considering the whole measurement. However, looking only at the last 10% of duration time (exhaustion), the MMGtri showed significantly higher amplitudes during PIMA.
Conclusion
The results suggest that under holding isometric conditions muscles exhaust earlier. That means that there are probably two forms of isometric muscle action. We hypothesize two potential reasons for faster yielding during HIMA: (1) earlier metabolic fatigue of the muscle fibers and (2) the complexity of neural control strategies.
Results of the experimental study support a distinction between a holding and a pushing isometric muscle function
urn:nbn:de:kobv:517-opus4-402084
online registration
BMC sports science, medicine & rehabilitation 9 (2017). - DOI: 10.1186/s13102-017-0075-z
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/40207">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
CC-BY - Namensnennung 4.0 International
Laura V. Schaefer
Frank N. Bittmann
Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
344
eng
uncontrolled
Holding isometric muscle action
eng
uncontrolled
Mechanomyography
eng
uncontrolled
Mechanotendography
eng
uncontrolled
Pushing isometric muscle action
eng
uncontrolled
Two forms of isometric muscle action
Medizin und Gesundheit
open_access
Strukturbereich Kognitionswissenschaften
Referiert
Open Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/40208/phr344_online.pdf