scholarly journals Muscle in Variable Gravity: “I Do Not Know Where I Am, But I Know What to Do”

2021 ◽  
Vol 12 ◽  
Author(s):  
Elena Monti ◽  
Janice Waldvogel ◽  
Ramona Ritzmann ◽  
Kathrin Freyler ◽  
Kirsten Albracht ◽  
...  
Keyword(s):  
Sarcomere Length ◽  
Joint Angle ◽  
Parabolic Flight ◽  
Published Data ◽  
Electromyographic Activity ◽  
Gravity Level ◽  
Muscle Fascicle ◽  
Drop Jumps ◽  
Variable Gravity ◽  
Sarcomere Number

Purpose: Fascicle and sarcomere lengths are important predictors of muscle mechanical performance. However, their regulation during stretch-shortening cycle (SSC) activities in usual and challenging conditions is poorly understood. In this study, we aimed to investigate muscle fascicle and sarcomere behavior during drop jumps (a common SSC activity) in conditions of variable gravity.Methods: Fifteen volunteers performed repeated drop jumps in 1 g, hypo-gravity (0 to 1 g), and hyper-gravity (1 to 2 g) during a parabolic flight. Gastrocnemius medialis (GM) electromyographic activity and fascicle length (Lf) were measured at drop-off, ground contact (GC), minimum ankle joint angle (MAJ), and push-off. GM sarcomere number was estimated by dividing Lf, measured by ultrasound at rest, by published data on GM sarcomere length, and measured in vivo at the same joint angle. Changes in sarcomere length were estimated by dividing GM Lf in each jump phase by sarcomere number calculated individually. The sarcomere force-generating capacity in each jump phase was estimated from the sarcomere length-tension relationship previously reported in the literature.Results: The results showed that, regardless of the gravity level, GM sarcomeres operated in the ascending portion of their length-tension relationship in all the jump phases. Interestingly, although in hypo-gravity and hyper-gravity during the braking phase (GC-MAJ) GM fascicles and sarcomeres experienced a stretch (as opposed to the quasi-isometric behavior in 1 g), at MAJ they reached similar lengths as in 1 g, allowing sarcomeres to develop about the 70% of their maximum force.Conclusion: The observed fascicle behavior during drop jumping seems useful for anchoring the tendon, enabling storage of elastic energy and its release in the subsequent push-off phase for effectively re-bouncing in all gravity levels, suggesting that an innate neuromuscular wisdom enables to perform SSC movements also in challenging conditions.

scholarly journals Boiling in variable gravity under the action of an electric field: results of parabolic flight experiments

2011 ◽  
Vol 327 ◽  
pp. 012039 ◽  
Author(s):  
P Di Marco ◽  
R Raj ◽  
J Kim
Keyword(s):  
Electric Field ◽  
Parabolic Flight ◽  
Variable Gravity

Reduced-Gravity Human Factors Research with Aircraft

1969 ◽  
Vol 11 (5) ◽  
pp. 463-471 ◽  
Author(s):  
Michael J. Moran
Keyword(s):  
Human Factors ◽  
Space Flight ◽  
Gravity Data ◽  
Parabolic Flight ◽  
Gravity Level ◽  
Reduced Gravity ◽  
Low Gravity ◽  
Simulation Techniques ◽  
Space Experiments ◽  
Actual Space

Human factors in a low-gravity environment became important with the beginning of manned space flight programs. The costs and dangers associated with actual space experiments necessitated the development of reduced-gravity simulation techniques. Since parabolic flight is the only way to produce approximately the same physical conditions as orbital space flight, it is the only technique acceptable for many human factors studies. However, the shortness of periods at the desired gravity level and the high gravity levels of the pre- and post-parabola flight compromise the effectiveness of the technique. In spite of its faults, this technique has been used to produce many meaningful studies. These studies have done much to increase our limited knowledge of reduced-gravity human factors. It appears that this technique will continue to be a main source of low-gravity data, until the era of manned orbiting laboratories.

scholarly journals Pressure based MRI-compatible muscle fascicle length and joint angle estimation

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Hyungeun Song ◽  
Erica Israel ◽  
Shriya Srinivasan ◽  
Hugh Herr
Keyword(s):  
Joint Angle ◽  
Fascicle Length ◽  
Angle Estimation ◽  
Muscle Fascicle

scholarly journals Effects of GaAs laser and stretching on muscle contusion in rats

2016 ◽  
Vol 23 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Daniela Gallon Corrêa ◽  
Juliana T. Okita ◽  
Hilana Rickli Fiuza Martins ◽  
Anna Raquel Silveira Gomes
Keyword(s):  
Connective Tissue ◽  
Sarcomere Length ◽  
Male Rats ◽  
Lesion Group ◽  
Control Group ◽  
Muscle Injuries ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Gaas Laser ◽  
Sarcomere Number

ABSTRACT Laser and stretching are used to treat skeletal muscle injuries. This study aimed to evaluate the effects of GaAs laser and stretching in the morphology of the tibialis anterior (TA) muscle after contusion. Thirty-six male rats (349±23g) were divided into six groups (n=6): control group (CG); lesion group (LG); lesion and laser group (LLG); lesion and stretching group (LSG); lesion, laser and stretching group (LLSG); and stretching group (SG). TA was wounded by a contusion apparatus. We used GaAs laser 4.5 J/cm2 dose for 32 s each, beginning 48 h after lesion, for 7 days, once a day. Manual passive stretching was applied by 10 repetitions for 1 minute, initiating on the 8th day, once a day, 3 times a week, during 3 weeks. After 4 weeks, rats were euthanized and we analyzed: muscle weight and length, cross sectional area of muscle fibers (CSAMF), serial sarcomere number (SSN), sarcomere length, and percentage of connective tissue. Comparisons among groups were made by ANOVA and post hoc Tukey tests, with the significance level set at ≤ 0.05. The serial sarcomere number of LLSG was higher than LSG. The sarcomere length of LSG was superior to LLG, LLSG, and SG. SG increased SSN compared to CG, while the percentage of connective tissue of SG decreased in comparison to LLSG. Thus, the sarcomerogenesis of injured muscles was enhanced by laser therapy, stretching, and association of both. The stretching protocol was enough to increase SSN of intact muscles.

scholarly journals Influence of joint angle on muscle fascicle dynamics and rate of torque development during isometric explosive contractions

2020 ◽  
Vol 129 (3) ◽  
pp. 569-579
Author(s):  
Robin Hager ◽  
Thomas Poulard ◽  
Antoine Nordez ◽  
Sylvain Dorel ◽  
Gaël Guilhem
Keyword(s):  
Joint Angle ◽  
Limiting Factor ◽  
Gastrocnemius Medialis ◽  
Rate Of Torque Development ◽  
Muscle Fascicle ◽  
Length Relationship ◽  
Ankle Angle ◽  
Generating Capacity ◽  
Force Velocity ◽  
Torque Development

Ankle angle influences the operating muscle fascicle lengths of gastrocnemius medialis and the rate of torque development during explosive isometric plantar flexions. The rate of torque development peaks in neutral angles where muscle fascicles shorten over the plateau of the force-length relationship. When fascicles operate over the plateau of the force-length relationship (neutral ankle positions), the force-velocity properties represent a limiting factor for the rapid force-generating capacity from 100 ms after the onset of explosive contractions.

Gravity Scaling Parameter for Pool Boiling Heat Transfer

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Rishi Raj ◽  
Jungho Kim ◽  
John McQuillen
Keyword(s):  
Heat Flux ◽  
Pool Boiling ◽  
Gravity Level ◽  
Dissolved Gas ◽  
Experimental Conditions ◽  
Scaling Parameter ◽  
Flux Data ◽  
Earth Gravity ◽  
Variable Gravity ◽  
Continuous Range

Although the effects of microgravity, earth gravity, and hypergravity (>1.5 g) on pool boiling heat flux have been studied previously, pool boiling heat flux data over a continuous range of gravity levels (0–1.7 g) was unavailable until recently. The current work uses the results of a variable gravity, subcooled pool boiling experiment to develop a gravity scaling parameter for n-perfluorohexane/FC-72 in the buoyancy-dominated boiling regime (Lh/Lc>2.1). The heat flux prediction was then validated using heat flux data at different subcoolings and dissolved gas concentrations. The scaling parameter can be used as a tool to predict boiling heat flux at any gravity level in the buoyancy dominated regime if the data under similar experimental conditions are available at any other gravity level.

Diaphragm in emphysematous hamsters: sarcomere adaptability

1983 ◽  
Vol 54 (6) ◽  
pp. 1635-1640 ◽  
Author(s):  
G. A. Farkas ◽  
C. Roussos
Keyword(s):  
Functional Residual Capacity ◽  
Sarcomere Length ◽  
Small Decrease ◽  
Optimal Length ◽  
Residual Capacity ◽  
Tension Curve ◽  
Sarcomere Number

We investigated whether the shift in the diaphragmatic length-tension curve of emphysematous animals was due to changes in either sarcomere number or sarcomere length. In vitro length-tension characteristics of the diaphragm were evaluated in control and emphysematous hamsters. Emphysema was induced by a single endotracheal instillation of elastase. Functional residual capacity, measured by means of a plethysmograph, was about twice that measured in emphysematous animals compared with control animals. Small diaphragmatic bundles were isolated and evaluated for their length-tension characteristics. The length-tension curve of diaphragms from emphysematous animals was displaced toward the left. Maximal tetanic tensions were similar in both groups, whereas optimal bundle length was significantly decreased in the emphysematous animals. Sarcomere number and sarcomere length at optimal length were then calculated for the diaphragmatic bundles. The bundles from emphysematous animals were found to have a significantly reduced number of sarcomeres, as well as a significantly decreased sarcomere length at optimal compared with control values. The total number of sarcomeres were also found to be significantly negatively correlated with the animal's functional residual capacity. From these results, we conclude that the decrease in diaphragmatic length, seen with hyperinflation, is due mainly to a loss of sarcomeres and possibly to a small decrease in sarcomere length measured at optimal bundle length.

scholarly journals Mechanistic insights into the modulatory role of the mechanoreflex on central hemodynamics using passive leg movement in humans

2018 ◽  
Vol 125 (2) ◽  
pp. 545-552 ◽  
Author(s):  
Nicholas T. Kruse ◽  
William E. Hughes ◽  
Darren P. Casey
Keyword(s):  
Cardiac Output ◽  
Angular Velocity ◽  
Range Of Motion ◽  
Joint Angle ◽  
Feedback Mechanism ◽  
Fascicle Length ◽  
Percent Change ◽  
Muscle Fascicle ◽  
Angular Velocities ◽  
Leg Movement

The aim of this study was to examine the independent contributions of joint range of motion (ROM), muscle fascicle length (MFL), and joint angular velocity on mechanoreceptor-mediated central cardiovascular dynamics using passive leg movement (PLM) in humans. Twelve healthy men (age: 23 ± 2 yr, body mass index: 23.7 kg/m2) performed continuous PLM at various randomized joint angle ROMs (0°–50° vs. 50°–100° vs. 0°–100°) and joint angular velocities (“fast”: 200°/s vs. “slow”: 100°/s). Measures of heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were recorded during baseline and during 60 s of PLM. MFL was calculated from muscle architectural measurements of fascicle pennation angle and tissue thickness (Doppler ultrasound). Percent change in MFL increased across the transition of PLM from 0° to 50° (15 ± 3%; P < 0.05) and from 0° to 100° knee flexion (27 ± 4%; P < 0.05). The average peak percent change in HR (increased, approx. +5 ± 2%; P < 0.05), CO (increased, approx. +5 ± 3%; P < 0.05), and MAP (decreased, approx. −2 ± 2%; P < 0.05) were similar between fast versus slow angular velocities when compared against shorter absolute joint ROMs (i.e., 0°–50° and 50°–100°). However, the condition that exhibited the greatest angular velocity in combination with ROM (0°–100° at 200°/s) elicited the greatest increases in HR (+13 ± 2%; P < 0.05) and CO (+12 ± 2%; P < 0.05) compared with all conditions. Additionally, there was a significant relationship between MFL and HR within 0°–100° at 200°/s condition ( r2 = 0.59; P < 0.05). These findings suggest that increasing MFL and joint ROM in combination with increased angular velocity via PLM are important components that activate mechanoreflex-mediated cardioacceleration and increased CO. NEW & NOTEWORTHY The mechanoreflex is an important autonomic feedback mechanism that serves to optimize skeletal muscle perfusion during exercise. The present study sought to explore the mechanistic contributions that initiate the mechanoreflex using passive leg movement (PLM). The novel findings show that progressively increasing joint angle range of motion and muscle fascicle length via PLM, in combination with increased angular velocity, are important components that activate mechanoreflex-mediated cardioacceleration and increase cardiac output in humans.

The Effects of Different Stretch Amplitudes on Electromyographic Activity During Drop Jumps

2008 ◽  
Vol 22 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Jenq-Dong Lin ◽  
Yu Liu ◽  
Jenq-Charng Lin ◽  
Feng-Jen Tsai ◽  
Chun-Yu Chao
Keyword(s):  
Electromyographic Activity ◽  
Drop Jumps
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