scholarly journals The effect of stretch–shortening magnitude and muscle–tendon unit length on performance enhancement in a stretch–shortening cycle

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martin Groeber ◽  
Savvas Stafilidis ◽  
Arnold Baca
Keyword(s):  
Performance Enhancement ◽  
Vastus Lateralis ◽  
Unit Length ◽  
Knee Kinematics ◽  
Joint Torque ◽  
Physiological Relevance ◽  
Significant Difference ◽  
Human Muscles ◽  
Stretch Shortening Cycle

AbstractStretch-induced residual force enhancement (rFE) is associated with increased performance in a stretch–shortening cycle (SSC). Although the influence of different range of motions and muscle–tendon unit lengths has been investigated in pure stretch-hold experiments in vivo, the contribution to a SSC movement in human muscles remains unclear. In two sessions, 25 healthy participants performed isometric reference (ISO), shortening hold (SHO) and SSC contractions on an isokinetic dynamometer. We measured the net knee-joint torque, rotational mechanical work, knee kinematics and fascicle behavior (m. vastus lateralis) of the upper right leg. In session 1 the SHO- and SSC-magnitude was changed respectively (SHO: 50°–20°, 80°–20° and 110°–20°; SSC: 20°–50°–20°, 20°–80°–20° and 20°–110°–20°) and in session 2 the muscle–tendon unit length (SHO: 50°–20°, 80°–50° and 110°–80°; SSC: 20°–50°–20°, 50°–80°–50° and 80°–110°–80°; straight leg = 0°). In both sessions, rotational work was significantly (p < 0.05) increased in the SSC compared to the SHO contractions (in the range of 8.1–17.9%). No significant difference of joint torque was found in the steady-state for all SSC-magnitudes compared to the corresponding SHO contractions in session 1. In session 2, we found only significantly (p < 0.05) less depressed joint torque in the SSC at the longest muscle–tendon unit length compared to the corresponding SHO condition, without any differences in knee kinematics and fascicle behavior. Therefore, the physiological relevance of rFE might be particularly important for movements at greater muscle–tendon unit lengths.

The Validity of Ultrasound Estimation of Muscle Volumes

2007 ◽  
Vol 23 (3) ◽  
pp. 213-217 ◽  
Author(s):  
Benjamin W. Infantolino ◽  
Daniel J. Gales ◽  
Samantha L. Winter ◽  
John H. Challis
Keyword(s):  
Vastus Lateralis ◽  
Intraclass Correlation ◽  
Accurate Method ◽  
Muscle Volume ◽  
Volume Estimation ◽  
Percentage Error ◽  
Ultrasound Images ◽  
Significant Difference ◽  
Hydrostatic Weighing

The purpose of this study was to validate ultrasound muscle volume estimation in vivo. To examine validity, vastus lateralis ultrasound images were collected from cadavers before muscle dissection; after dissection, the volumes were determined by hydrostatic weighing. Seven thighs from cadaver specimens were scanned using a 7.5-MHz ultrasound probe (SSD-1000, Aloka, Japan). The perimeter of the vastus lateralis was identified in the ultrasound images and manually digitized. Volumes were then estimated using the Cavalieri principle, by measuring the image areas of sets of parallel two-dimensional slices through the muscles. The muscles were then dissected from the cadavers, and muscle volume was determined via hydrostatic weighing. There was no statistically significant difference between the ultrasound estimation of muscle volume and that estimated using hydrostatic weighing (p> 0.05). The mean percentage error between the two volume estimates was 0.4% ± 6.9. Three operators all performed four digitizations of all images from one randomly selected muscle; there was no statistical difference between operators or trials and the intraclass correlation was high (>0.8). The results of this study indicate that ultrasound is an accurate method for estimating muscle volumes in vivo.

The Influence of Fascicle Behavior on the Lack of Velocity Dependence in Eccentric Joint Torque in Humans: In Vivo Observation

2009 ◽  
Vol 25 (2) ◽  
pp. 111-118 ◽  
Author(s):  
Kentaro Chino ◽  
Naotoshi Mitsukawa ◽  
Kai Kobayashi ◽  
Yusuke Miyoshi ◽  
Toshiaki Oda ◽  
...  
Keyword(s):  
Plantar Flexion ◽  
Triceps Surae ◽  
Joint Torque ◽  
Fascicle Length ◽  
Significant Difference ◽  
Isometric Torque ◽  
The Difference ◽  
The Relationship ◽  
Real Time Ultrasonography

To investigate the relationship between fascicle behavior and joint torque, the fascicle behavior of the triceps surae during isometric and eccentric (30 and 60 deg/s) plantar flexion by maximal voluntary and submaximal electrical activation (MVA and SEA) was measured by real-time ultrasonography. Eccentric torque at 30 and 60 deg/s was significantly higher than isometric torque under SEA, but not under MVA. However, fascicle length did not significantly differ between isometric and eccentric trials under either condition. Therefore, the difference in developed torque by MVA and SEA cannot be explained by fascicle behavior. Under both MVA and SEA conditions, eccentric torque at 30 and 60 deg/s was equivalent. Similarly, fascicle lengthening velocities at 30 and 60deg/s did not show any significant difference. Such fascicle behavior can be attributed to the influence of tendinous tissue and pennation angle, and lead to a lack of increase in eccentric torque with increasing angular velocity.

scholarly journals Comparação do ciclo alongamento-encurtamento em saltos verticais entre mulheres ativas adultas-jovens e idosas

2018 ◽  
Vol 6 (1) ◽  
pp. 15
Author(s):  
Hyago Bernardes da Rosa ◽  
Igor Martins Barbosa ◽  
Eduardo Porto Scisleski ◽  
Samuel Klippel Prusch ◽  
Luiz Fernando Cuozzo Lemos
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Vastus Lateralis Muscle ◽  
Electromyographic Activity ◽  
Counter Movement Jump ◽  
Vertical Jumping ◽  
Significant Difference ◽  
Stretch Shortening Cycle

PURPOSE: To verify if there is an electromyographic economy and/or an increase in the variables of vertical jumps, both as a function of the use of the Stretch-Shortening Cycle and to compare the findings between young and old women, both active. METHODS: The sample consisted of a group of elderly (GI) and a group of young (GJ), both female. The power was measured through the contact platform and electromyographic activity of the muscles: biceps femoris (BF), rectus femoris (RF), medial gastrocnemius and vastus lateralis, through vertical jumping tests: Squat Jump (SJ) and Counter Movement Jump (CMJ). RESULTS: All the muscles evaluated did not present a statistically significant difference in the electromyographic activation and the comparisons of the mean percentage of use of the Stretch-Shortening Cycle (CAE), but it was observed that for the vastus lateralis and rectus femoris muscles there were significant differences in the comparisons between the two types of jumps of both groups, GI (236.89±115.66 for SJ and 230.45±109.10 for vastus lateralis muscle (VL) CMJ and 155.42±49.06 for SJ and 155 , 45±61.78 for the CMJ of the RF muscle) required greater neuromuscular activation to jump less than GJ (117.40±133.09 for SJ and 133.09±60.71 for VL muscle CMJ and 106.72±34.15 for the SJ and 108.87±38.85 for the CMJ of the RF muscle). CONCLUSIONS: The present study confirms that there was no statistically significant difference in the use of CAE in both groups (GI and GJ). However, when it comes to the skipped height and the power developed, there were statistically significant differences in the comparison of the groups.

scholarly journals Comparison of in vivo knee kinematics before and after bicruciate-stabilized total knee arthroplasty during squatting

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Masato Kiyohara ◽  
Satoshi Hamai ◽  
Hirotaka Gondo ◽  
Hidehiko Higaki ◽  
Satoru Ikebe ◽  
...  
Keyword(s):  
Rotation Angle ◽  
Knee Kinematics ◽  
Significant Difference ◽  
Before And After ◽  
Rotational Mismatch ◽  
Total Knee ◽  
Skeletal Kinematics ◽  
Functional Extension ◽  
Mismatch Angle

Abstract Background No studies have directly evaluated kinematic changes during squatting before and after bicruciate-stabilized total knee arthroplasty (BCS-TKA) with the dual cam-post mechanism and asymmetric surfaces. This study investigated the effect of BCS-TKA on changes to pre- and postoperative skeletal knee kinematics, to identify factors associated with postoperative skeletal kinematic parameters. Methods Seventeen knees in 17 patients were prospectively recruited before primary TKA for advanced medial knee osteoarthritis. Subjects underwent BCS-TKA and were evaluated more than 1 year postoperatively. In vivo dynamic skeletal knee kinematics were evaluated using periodic radiographic images collected during squatting to quantify the tibiofemoral functional extension/flexion angle, anteroposterior (AP) translation, and axial rotation angle using image-matching techniques. Rotational alignments of femoral and tibial components were measured postoperatively using computed tomography images. Results The pre- and postoperative tibiofemoral functional extension/flexion angles during squatting were 12.2° ± 6.7°/100.1° ± 16.8° and 9.6° ± 8.6°/109.4° ± 16.8°, respectively, with a significant difference in flexion angle (p < .05). Total AP translation was significantly larger postoperatively than preoperatively (10.8 mm ± 3.7 mm vs. 14.4 mm ± 4.2 mm, respectively; p < .05). The pre- and postoperative total rotation angles were 6.6° ± 3.0° and 6.4° ± 3.7°, respectively, indicating no significant difference. The pre- and postoperative tibiofemoral functional flexion angles were significantly associated with each other (p = .0434, r = .49). The postoperative total rotation angle was significantly smaller when the total component rotational mismatch angle between the femoral and tibial components was above 5° vs. below 5° (4.6° ± 2.7° vs. 8.3° ± 3.9°, respectively; p < .05). Conclusions BCS-TKA significantly increased the tibiofemoral functional flexion angles, with larger AP translation postoperatively. Both preoperative skeletal kinematics and surgical techniques affected the skeletal kinematics of the replaced knee. A total component rotational mismatch angle greater than 5° significantly decreased postoperative total knee rotation during squatting.

scholarly journals An Improved EMG-Driven Neuromusculoskeletal Model for Elbow Joint Muscle Torque Estimation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Bingshan Hu ◽  
Haoran Tao ◽  
Hongrun Lu ◽  
Xiangxiang Zhao ◽  
Jiantao Yang ◽  
...  
Keyword(s):  
Geometric Model ◽  
Pearson Correlation ◽  
Joint Torque ◽  
Muscle Coordination ◽  
Muscle Torque ◽  
Significant Difference ◽  
Double Muscle ◽  
Neuromusculoskeletal Model ◽  
Improved Model

The accurate measurement of human joint torque is one of the research hotspots in the field of biomechanics. However, due to the complexity of human structure and muscle coordination in the process of movement, it is difficult to measure the torque of human joints in vivo directly. Based on the traditional elbow double-muscle musculoskeletal model, an improved elbow neuromusculoskeletal model is proposed to predict elbow muscle torque in this paper. The number of muscles in the improved model is more complete, and the geometric model is more in line with the physiological structure of the elbow. The simulation results show that the prediction results of the model are more accurate than those of the traditional double-muscle model. Compared with the elbow muscle torque simulated by OpenSim software, the Pearson correlation coefficient of the two shows a very strong correlation. One-way analysis of variance (ANOVA) showed no significant difference, indicating that the improved elbow neuromusculoskeletal model established in this paper can well predict elbow muscle torque.

Influence of elastic properties of tendon structures on jump performance in humans

1999 ◽  
Vol 87 (6) ◽  
pp. 2090-2096 ◽  
Author(s):  
Keitaro Kubo ◽  
Yasuo Kawakami ◽  
Tetsuo Fukunaga
Keyword(s):  
Elastic Properties ◽  
Vastus Lateralis ◽  
Vertical Jump ◽  
Knee Extension ◽  
Favorable Effect ◽  
Vastus Lateralis Muscle ◽  
Jump Height ◽  
Jump Performance ◽  
Significant Difference

The purpose of this study was to quantify the elastic properties of tendon structures in vivo and to investigate the influence of the tendon properties on jump performance with and without countermovement. Elongation of the tendon and aponeurosis of vastus lateralis muscle (d L) was directly measured by ultrasonography while subjects ( n = 31) performed ramp isometric knee extension up to the voluntary maximum (MVC). The relationship between muscle force and d L was fitted to a linear regression above 50% MVC, the slope of which was defined as stiffness of the tendon structures. Statistical analysis revealed no significant difference between duplicated measurements of stiffness, with an interday reliability of r = 0.88 and a coefficient of variance of 6.1%. Although the stiffness was not significantly related to absolute jump height in either vertical jump, it was inversely correlated with the difference in jump height between the vertical jumps performed with and without countermovement. The results suggested that the stiffness of tendon structures has a favorable effect on stretch-shortening cycle exercise, possibly due to adequate storage and recoil of elastic energy.

In-vivo evaluation of the effect of cyanoacrylate on prosthetic vascular graft infection – does cyanoacrylate increase the severity of infection?

VASA ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 281-284
Author(s):  
Atıf Yolgosteren ◽  
Gencehan Kumtepe ◽  
Melda Payaslioglu ◽  
Cuneyt Ozakin
Keyword(s):  
Vascular Graft ◽  
Graft Infection ◽  
Vascular Graft Infection ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Prosthetic Vascular Graft Infection ◽  
Group 1

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.

In-vivo anti-oxidant screening of Tectona grandis extract

2020 ◽  
Vol 9 (1) ◽  
pp. 1-4
Author(s):  
Tamilarasi G P ◽  
Sabarees G
Keyword(s):  
Biochemical Parameters ◽  
Tectona Grandis ◽  
The Body ◽  
Altered Expression ◽  
Physiological Conditions ◽  
Synthetic Drugs ◽  
Significant Difference ◽  
Anti Oxidant ◽  
Radical Generation

Oxidation is an essential reaction in the human body, which determines the expression of proteins in the body. This results in the altered expression like rapid growth resulting in cancers and other disorders. Many synthetic drugs are available in the market that is effective in limiting the free radical generation and the reaction of radicals with cells. Unfortunately, all those synthetic drugs were found to cause side effects and adverse effects in the body. But given the accuracy of the predictability of the results and administration, this research focuses on testing the anti-oxidant efficiency in rat models testing the biochemical parameters. Investigations have also been done on the anti-oxidant activity of Tectona, but every research was concentrated to prove the anti-oxidant activity only. extract had been tested for anti-oxidant activity by estimating various tissue parameters and it showed better activity. As predicted, there is a significant difference in the and results which can be explained are due to the physiological conditions that exist inside the body.

Alternativas farmacéuticas: ¿pueden ser intercambiables?

2020 ◽  
Vol 2 (2) ◽  
pp. 38-42
Author(s):  
Miriam del Carmen Carrasco-Portugal ◽  
Francisco Javier Flores-Murrieta
Keyword(s):  
Generic Substitution ◽  
In Vivo Studies ◽  
Regulatory Agencies ◽  
European Medicines Agency ◽  
Reference Formulation ◽  
Active Moiety ◽  
Significant Difference ◽  
Pharmaceutical Form ◽  
Extent Of Absorption

Pharmaceutical alternatives are products with the same active moiety, but different salt, ester or pharmaceutical form. Regulatory agencies have different criteria for this kind of drug. The European Medicines Agency (EMA) accepts the generic substitution using these alternatives, whereas the Food and Drug Administration (FDA) only authorizes generic substitution of pharmaceutical equivalents. The objective of this paper is to describe some relevant aspects that should be considered before deciding on making a generic substitution with pharmaceutical alternatives. It is important to note that a pharmaceutical alternative must show no significant difference in the rate and extent of absorption (bioequivalence) in a well-conducted in vivo study when compared with the reference formulation. Current Mexican regulations state that generic substitution is possible using pharmaceutical alternatives when bioequivalence is demonstrated in in vivo studies conducted under the NOM-177-SSA1-2013 criteria. In conclusion, generic substitution with pharmaceutical alternatives is possible if these products demonstrate in vivo bioequivalence when compared with the reference product.

Development of Mucoadhesive Buccal Drug Delivery System of Propranolol Hydrochloride Using Aster ericoides Mucilage

2020 ◽  
Vol 10 (2) ◽  
pp. 133-148
Author(s):  
Ankaj Kaundal ◽  
Pravin Kumar ◽  
Rajendra Awasthi ◽  
Giriraj T. Kulkarni
Keyword(s):  
Buccal Cavity ◽  
Three Dimensional ◽  
Hot Water ◽  
Fickian Diffusion ◽  
Aster Ericoides ◽  
Dimensional Network ◽  
Buccal Tablet ◽  
Significant Difference ◽  
Volunteer Group

Aim: The study was aimed to develop mucoadhesive buccal tablets using Aster ericoides leaves mucilage. Background : Mucilages are naturally occurring high-molecular-weight polyuronides, which have been extensively studied for their application in different pharmaceutical dosage forms. Objective: The objective of the present research was to establish the mucilage isolated from the leaves of Aster ericoides as an excipient for the formulation of the mucoadhesive buccal tablet. Method: The mucilage was isolated from the leaves of Aster ericoides by maceration, precipitated with acetone and characterized. Tablets were prepared using wet granulation technique and evaluated for various official tests. Results: The mucilage was found to be non-toxic on A-431 and Vero cell lines. It was insoluble but swellable in cold and hot water. The results indicate that mucilage can form a three-dimensional network. The pH of the mucilage (6.82 ± 0.13) indicated that it might be non-irritant to the buccal cavity. The mucilage was found to be free from microbes. The release of drug was by Fickian diffusion. The in vivo buccal tablet acceptance was 80%. No significant difference between the diastolic blood pressure of standard and Aster tablets treated volunteer group was recorded. Conclusion: The mucilage was found to be non-toxic on A-431 and Vero cell lines. It was insoluble but swellable in cold and hot water. The results indicate that mucilage can form a three-dimensional network. The pH of the mucilage (6.82 ± 0.13) indicated that it might be non-irritant to the buccal cavity. The mucilage was found to be free from microbes. The release of drug was by Fickian diffusion. The in vivo buccal tablet acceptance was 80%. No significant difference between the diastolic blood pressure of standard and Aster tablets treated volunteer group was recorded. Other: However, to prove the potency of the polymer, in vivo bioavailability studies in human volunteers are needed along with chronic toxicity studies in suitable animal models.

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