scholarly journals Plantarflexor Torque and Work is Positively Correlated with Medial Gastrocnemius Fascicle Length in Healthy Young Adults

2019 ◽  
Author(s):  
John F Drazan ◽  
Todd J Hullfish ◽  
Josh R Baxter
Keyword(s):  
Young Adults ◽  
Healthy Adult ◽  
Peak Torque ◽  
The Elderly ◽  
Medial Gastrocnemius ◽  
Total Work ◽  
Fascicle Length ◽  
Muscle Structure ◽  
The Relationship ◽  
Maximal Effort

ABSTRACTAnkle kinetics are critical for ambulatory function in elite athletes, the elderly, and many patient populations. Despite the robust findings linking plantarflexor muscle structure to gross function with these populations, the link between plantarflexor fascicle length and ankle kinetics has not been established in the literature. In this study, we determined the relationship between muscle structure and peak torque and total work produced by the plantarflexors during maximal effort contractions. We measured resting fascicle length and pennation angle of the medial gastrocnemius using ultrasound in healthy adult subjects (n=12). Subjects performed contractions on a dynamometer during isokinetic and isometric conditions. Longer fascicles were positively correlated with higher peak torque and total work (R2 > 0.41, p < 0.013) across all isokinetic velocities. Higher pennation angles were negatively correlated with peak torque and total work (R2 > 0.296, p < 0.067). None of these correlations were significant in isometric conditions. This provides experimental evidence demonstrating the link between plantarflexor muscle structure and ankle kinetics in healthy young adults which has hitherto not been experimentally demonstrated in existing literature.

scholarly journals Gastrocnemius muscle remodeling explains functional deficits three months following Achilles tendon rupture

2019 ◽  
Author(s):  
Todd J. Hullfish ◽  
Kathryn M. O’Connor ◽  
Josh R. Baxter
Keyword(s):  
Achilles Tendon ◽  
Gastrocnemius Muscle ◽  
Tendon Rupture ◽  
Achilles Tendon Rupture ◽  
Peak Torque ◽  
Pennation Angle ◽  
Medial Gastrocnemius ◽  
Fascicle Length ◽  
Functional Deficits ◽  
Muscle Remodeling

ABSTRACTPlantarflexor functional deficits are associated with poor outcomes in patients following Achilles tendon rupture. In this longitudinal study, we analyzed the fascicle length and pennation angle of the medial gastrocnemius muscle and the length of the Achilles tendon using ultrasound imaging. To determine the relationship between muscle remodeling and functional deficits measured at 3 months after injury, we correlated the reduction in fascicle length and increase in pennation angle with peak torque measured during isometric plantarflexor contractions and peak power measured during isokinetic plantarflexor contractions. We found that the medial gastrocnemius underwent an immediate change in structure, characterized by decreased length and increased pennation of the muscle fascicles. This decrease in fascicle length was coupled with an increase in tendon length. These changes in muscle-tendon structure persisted throughout the first three months following rupture. Deficits in peak plantarflexor power were moderately correlated with decreased fascicle length at 120 degrees per second (R2= 0.424,P= 0.057) and strongly correlated with decreased fascicle length at 210 degrees per second (R2= 0.737,P= 0.003). However, increases in pennation angle did not explain functional deficits. These findings suggest that muscle-tendon structure is detrimentally affected following Achilles tendon rupture. Plantarflexor power deficits are positively correlated with the magnitude of reductions in fascicle length. Preserving muscle structure following Achilles tendon rupture should be a clinical priority to maintain patient function.

scholarly journals Gastrocnemius Muscle Structure Remodels Within the First Month Following Acute Achilles Tendon Rupture

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0032
Author(s):  
Kathryn M O’Connor ◽  
Todd J. Hullfish ◽  
Josh R. Baxter
Keyword(s):  
Achilles Tendon ◽  
Gastrocnemius Muscle ◽  
Tendon Rupture ◽  
Achilles Tendon Rupture ◽  
Pennation Angle ◽  
Medial Gastrocnemius ◽  
Muscle Quality ◽  
Fascicle Length ◽  
Muscle Structure ◽  
Tendon Ruptures

Category: Sports, Trauma, Achilles Tendon Introduction/Purpose: Two out of three patients Achilles tendon ruptures have limited plantarflexor function 1-year following Achilles tendon rupture. While tendon elongation has been reported as a possible mechanism of functional deficits, the effects of rupture on plantarflexor muscle structure has not been as rigorously investigated. A recent study found that gastrocnemius fascicle length was decreased 6-months following Achilles tendon rupture compared to the uninjured limb. However, the changes in muscle structure following the first month of injury – when the healing tendon is most susceptible to elongation – has not yet been established. The purpose of this study was to quantify the structural changes to the medial gastrocnemius in patients who suffered acute Achilles tendon ruptures and were treated non-operatively. Methods: To test our hypothesis that plantarflexor structure would undergo rapid remodeling following Achilles tendon rupture, we quantified muscle structure in ten patients (9 male, Age: 44 ± 12; BMI: 28.6 ± 6.5) who provide informed written consent in this IRB approved study. We acquired B-mode ultrasound images of the medial gastrocnemius muscle at the initial presentation (week 0), two weeks, and four weeks following the injury. The same investigator acquired all the ultrasound images and measured fascicle length, pennation angle, muscle thickness, and echo intensity. These measurements had a coefficient of variation less than 10%. We compared these structural measurements of the injured muscle at each time point with the contralateral muscle scans at the initial presentation using paired t-tests. Results: Gastrocnemius muscle structure following an acute Achilles tendon rupture differed with the healthy-contralateral muscle throughout the first four weeks following injury (Figure). Fascicle length was 15% shorter (P < 0.001) and pennation angle was 21% greater (P < 0.001) at the presentation of injury (week 0). These differences in fascicle length (P < 0.001) and pennation angle persisted throughout the 4 weeks after the injury (P < 0.008). Muscle thickness changes were not detected at any of the post-injury visits. Muscle quality, measured as mean echo intensity, was 8% lower in the injured limb immediately (P= 0.008) and 11% lower 2 weeks following injury (P < 0.001). At week 4 muscle quality had returned to within 1% of the contralateral limb (P = 0.393). Conclusion: Our findings support our hypothesis that the gastrocnemius muscle fascicles of the affected side would demonstrate shorter length and greater pennation angle than the contralateral control muscle. These findings are a preliminary set of data from a larger clinical cohort of patients that were enrolled in an ongoing 1-year long prospective study. Achilles tendon ruptures elicit rapid changes in the configuration and quality of the medial gastrocnemius, which may explain long-term functional deficits.

scholarly journals The length dependence of muscle active force: considerations for parallel elastic properties

2005 ◽  
Vol 98 (5) ◽  
pp. 1666-1673 ◽  
Author(s):  
Brian R. MacIntosh ◽  
Meredith B. MacNaughton
Keyword(s):  
Muscle Length ◽  
Element Model ◽  
Medial Gastrocnemius ◽  
Elastic Component ◽  
Contractile Element ◽  
Total Force ◽  
Passive Force ◽  
Active Force ◽  
Fascicle Length ◽  
The Relationship

The purpose of this study was to choose between two popular models of skeletal muscle: one with the parallel elastic component in parallel with both the contractile element and the series elastic component ( model A), and the other in which it is in parallel with only the contractile element ( model B). Passive and total forces were obtained at a variety of muscle lengths for the medial gastrocnemius muscle in anesthetized rats. Passive force was measured before the contraction ( passive A) or was estimated for the fascicle length at which peak total force occurred ( passive B). Fascicle length was measured with sonomicrometry. Active force was calculated by subtracting passive ( A or B) force from peak total force at each fascicle or muscle length. Optimal length, that fascicle length at which active force is maximized, was 13.1 ± 1.2 mm when passive A was subtracted and 14.0 ± 1.1 mm with passive B ( P < 0.01). Furthermore, the relationship between double-pulse contraction force and length was broader when calculated with passive B than with passive A. When the muscle was held at a long length, passive force decreased due to stress relaxation. This was accompanied by no change in fascicle length at the peak of the contraction and only a small corresponding decrease in peak total force. There is no explanation for the apparent increase in active force that would be obtained when subtracting passive A from the peak total force. Therefore, to calculate active force, it is appropriate to subtract passive force measured at the fascicle length corresponding to the length at which peak total force occurs, rather than passive force measured at the length at which the contraction begins.

scholarly journals Medial gastrocnemius muscle remodeling correlates with reduced plantarflexor kinetics 14 weeks following Achilles tendon rupture

2019 ◽  
Vol 127 (4) ◽  
pp. 1005-1011 ◽  
Author(s):  
Todd J. Hullfish ◽  
Kathryn M. O’Connor ◽  
Josh R. Baxter
Keyword(s):  
Achilles Tendon ◽  
Gastrocnemius Muscle ◽  
Tendon Rupture ◽  
Achilles Tendon Rupture ◽  
Peak Torque ◽  
Pennation Angle ◽  
Medial Gastrocnemius ◽  
Fascicle Length ◽  
Muscle Remodeling ◽  
Medial Gastrocnemius Muscle

Deficits in plantarflexor kinetics are associated with poor outcomes in patients following Achilles tendon rupture. In this longitudinal study, we analyzed the fascicle length and pennation angle of the medial gastrocnemius muscle and the length of the Achilles tendon using ultrasound imaging. To determine the relationship between muscle remodeling and deficits in plantarflexor kinetics measured at 14 wk after injury, we correlated the reduction in fascicle length and increase in pennation angle with peak torque measured during isometric and isokinetic plantarflexor contractions. We found that the medial gastrocnemius underwent an immediate change in structure, characterized by decreased length and increased pennation of the muscle fascicles. This decrease in fascicle length was coupled with an increase in tendon length. These changes in muscle-tendon structure persisted throughout the first 14 wk following rupture. Deficits in peak plantarflexor torque were moderately correlated with decreased fascicle length at 120 degrees per second ( R2 = 0.424, P = 0.057) and strongly correlated with decreased fascicle length at 210 degrees per second ( R2 = 0.737, P = 0.003). However, increases in pennation angle did not explain functional deficits. These findings suggest that muscle-tendon structure is detrimentally affected following Achilles tendon rupture. Plantarflexor power deficits are positively correlated with the magnitude of reductions in fascicle length. Preserving muscle structure following Achilles tendon rupture should be a clinical priority to maintain plantarflexor kinetics. NEW & NOTEWORTHY In our study, we found that when the Achilles tendon ruptures due to excessive biomechanical loading, the neighboring skeletal muscle undergoes rapid changes in its configuration. The magnitude of this muscle remodeling explains the amount of ankle power loss demonstrated by these patients once their Achilles tendons are fully healed. These findings highlight the interconnected relationship between muscle and tendon. Isolated injuries to the tendon stimulate detrimental changes to the muscle, thereby limiting joint-level function.

scholarly journals An automatic fascicle tracking algorithm quantifying gastrocnemius architecture during maximal effort contractions

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7120 ◽  
Author(s):  
John F. Drazan ◽  
Todd J. Hullfish ◽  
Josh R. Baxter
Keyword(s):  
Pennation Angle ◽  
Tracking Algorithm ◽  
Medial Gastrocnemius ◽  
Fascicle Length ◽  
Automatic Tracking ◽  
Individual Muscle ◽  
Muscle Fascicle ◽  
Muscle Fascicles ◽  
Maximal Effort ◽  
Strong Agreement

Background Ultrasound has become a commonly used imaging modality for making dynamic measurements of muscle structure during functional movements in biomechanical studies. Manual measurements of fascicle length and pennation angle are time intensive which limits the clinical utility of this approach while also limiting sample sizes in research. The purpose of this study was to develop an automatic fascicle tracking program to quantify the length and pennation angle of a muscle fascicle during maximal effort voluntary contractions and to evaluate its repeatability between days and reproducibility between different examiners. Methods Five healthy adults performed maximal effort isometric and isokinetic contractions at 30, 120, 210, and 500 degrees per second about their ankle on an isokinetic dynamometer while their medial gastrocnemius muscle was observed using ultrasound. Individual muscle fascicles and the two aponeuroses were identified by the user in the first frame and automatically tracked by the algorithm by three observers on three separate days. Users also made manual measurements of the candidate fascicle for validation. Repeatability within examiners across days and reproducibility across examiners and days were evaluated using intra-class correlation coefficients (ICC). Agreement between manual and automatic tracking was evaluated using the coefficient of multiple correlations (CMC) and root-mean-square error. Supervised automatic tracking, where the program could be reinitialized if poor tracking was observed, was performed on all videos by one examiner to evaluate the performance of automatic tracking in a typical use case. We also compared the performance our program to a preexisting automatic tracking program. Results We found both manual and automatic measurements of fascicle length and pennation angle to be strongly repeatable within examiners and strongly reproducible across examiners and days (ICCs > 0.74). There was greater agreement between manual and automatic measurements of fascicle length than pennation angle, however the mean CMC value was found to be strong in both cases (CMC > 0.8). Supervision of automatic tracking showed very strong agreement between manual and automatic measurements of fascicle length and pennation angle (CMC > 0.94). It also had considerably less error relative to the preexisting automatic tracking program. Conclusions We have developed a novel automatic fascicle tracking algorithm that quantifies fascicle length and pennation angle of individual muscle fascicles during dynamic contractions during isometric and across a range of isokinetic velocities. We demonstrated that this fascicle tracking algorithm is strongly repeatable and reproducible across different examiners and different days and showed strong agreement with manual measurements, especially when tracking is supervised by the user so that tracking can be reinitialized if poor tracking quality is observed.

scholarly journals The Relationship of Age, Strain and Species to the Reducing Activity of Leukocytes

Blood ◽  
1959 ◽  
Vol 14 (9) ◽  
pp. 1033-1039 ◽  
Author(s):  
ALBINA ANN YAKAITIS
Keyword(s):  
Young Adults ◽  
Young Adult ◽  
Healthy Adult ◽  
Young Rats ◽  
Adult Mice ◽  
Reducing Activity ◽  
Relationship Of ◽  
High Degree ◽  
The Relationship ◽  
Old Mice

Abstract A method is presented for studying the reducing activity of leukocytes of mice and rats using 2-(p-iodophenyl)-3-)p-nitrophenyl)-5-phenyltetrazolium chloride (INT). Between 48.0 per cent and 83.8 per cent of the leukocytes of young adult mice and between 47.8 per cent and 68.0 per cent of the leukocytes of young rats showed formazan formation. Infant mice of C3Hf and BALBf strains had appreciably fewer leukocytes with the ability to reduce tetrazolium than did young adults of their respective strains. Healthy adult mice belonging to the leukemia susceptible AKR strain showed a relatively high degree of leukocytic reduction. Old mice of the C3Hfstrain showed less formazan formation than young adult animals. This decrease was more marked for the male members of the species.

The Relationship between Lower Extremity Isokinetic Work and Single-Leg Functional Hop-Work Test

2006 ◽  
Vol 15 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Robert English ◽  
Mary Brannock ◽  
Wan Ting Chik ◽  
Laura S. Eastwood ◽  
Tim Uhl
Keyword(s):  
Body Weight ◽  
Lower Extremity ◽  
Outcome Measures ◽  
Study Design ◽  
Peak Torque ◽  
Knee Extension ◽  
Isokinetic Strength ◽  
Total Work ◽  
Lower Extremity Strength ◽  
The Relationship

Context:Lower extremity functional testing assesses strength, power, and neuro-muscular control. There are only moderate correlations between distance hopped and isokinetic strength measures.Objective:Determine if incorporating body weight in the single-leg hop for distance increases the correlation to isokinetic measures.Study Design:Correlational study.Setting:Musculoskeletal laboratory.Participants:30 healthy college students; 15 men and 15 women; ages 18 to 30 years.Main Outcome Measures:Isokinetic average peak torque and total work of quadriceps and hamstrings and single-leg hop work and distance.Results:Significant correlations include hop work to total-work knee extension (r= .89), average peak-torque knee extension (r= .88), distance hopped to total-work knee extension (r= .56) and average peak-torque knee extension (r= .63). Correlations involving hop work were greater than distance hopped (P< .05).Conclusions:Use of body weight in the assessment of distance hopped provides better information about the patient’s lower extremity strength and ability than the distance hopped alone.

The Relationship Between Narcissism and Personality Traits of the Five-Factor-Model in Adolescents and Young Adults

2018 ◽  
Vol 46 (6) ◽  
pp. 516-522 ◽  
Author(s):  
Marc Allroggen ◽  
Peter Rehmann ◽  
Eva Schürch ◽  
Carolyn C. Morf ◽  
Michael Kölch
Keyword(s):  
Young Adults ◽  
Personality Traits ◽  
Five Factor Model ◽  
Self Report ◽  
Adolescents And Young Adults ◽  
Personality Factors ◽  
Big Five Personality ◽  
Grandiose Narcissism ◽  
Vulnerable Narcissism ◽  
The Relationship

Abstract.Narcissism is seen as a multidimensional construct that consists of two manifestations: grandiose and vulnerable narcissism. In order to define these two manifestations, their relationship to personality factors has increasingly become of interest. However, so far no studies have considered the relationship between different phenotypes of narcissism and personality factors in adolescents. Method: In a cross-sectional study, we examine a group of adolescents (n = 98; average age 16.77 years; 23.5 % female) with regard to the relationship between Big Five personality factors and pathological narcissism using self-report instruments. This group is compared to a group of young adults (n = 38; average age 19.69 years; 25.6 % female). Results: Grandiose narcissism is primarily related to low Agreeableness and Extraversion, vulnerable narcissism to Neuroticism. We do not find differences between adolescents and young adults concerning the relationship between grandiose and vulnerable narcissism and personality traits. Discussion: Vulnerable and grandiose narcissism can be well differentiated in adolescents, and the pattern does not show substantial differences compared to young adults.

Investigating the Relationship Between Self-Esteem and Stigma Among Young Adults With History of Suicide Attempts

Crisis ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 265-270 ◽  
Author(s):  
Meshan Lehmann ◽  
Matthew R. Hilimire ◽  
Lawrence H. Yang ◽  
Bruce G. Link ◽  
Jordan E. DeVylder
Keyword(s):  
Young Adults ◽  
Suicide Attempts ◽  
Self Esteem ◽  
High Risk Population ◽  
High Functioning ◽  
People With Mental Illness ◽  
History Of ◽  
The Individual ◽  
The Impact ◽  
The Relationship

Abstract. Background: Self-esteem is a major contributor to risk for repeated suicide attempts. Prior research has shown that awareness of stigma is associated with reduced self-esteem among people with mental illness. No prior studies have examined the association between self-esteem and stereotype awareness among individuals with past suicide attempts. Aims: To understand the relationship between stereotype awareness and self-esteem among young adults who have and have not attempted suicide. Method: Computerized surveys were administered to college students (N = 637). Linear regression analyses were used to test associations between self-esteem and stereotype awareness, attempt history, and their interaction. Results: There was a significant stereotype awareness by attempt interaction (β = –.74, p = .006) in the regression analysis. The interaction was explained by a stronger negative association between stereotype awareness and self-esteem among individuals with past suicide attempts (β = –.50, p = .013) compared with those without attempts (β = –.09, p = .037). Conclusion: Stigma is associated with lower self-esteem within this high-functioning sample of young adults with histories of suicide attempts. Alleviating the impact of stigma at the individual (clinical) or community (public health) levels may improve self-esteem among this high-risk population, which could potentially influence subsequent suicide risk.

Does Ego-Resilience Impact Friendship Outcomes?

2016 ◽  
Vol 37 (2) ◽  
pp. 128-134 ◽  
Author(s):  
Elizabeth B. Lozano ◽  
Mahzad Hojjat ◽  
Judith Sims-Knight
Keyword(s):  
Social Support ◽  
Young Adults ◽  
Indirect Effects ◽  
Positive Emotions ◽  
Positive Outcomes ◽  
Ego Resilience ◽  
Maintenance Behaviors ◽  
Received Social Support ◽  
Trait Resilience ◽  
The Relationship

Abstract. The present study examined the relationship between resilience and positive outcomes in friendships of young adults. SEM and bootstrapping analyses were performed to test whether positive emotions mediate the relationship between ego-resilience and enhanced friendship outcomes. Findings revealed indirect effects for friendship closeness, maintenance behaviors, and received social support. Our findings demonstrate the importance of positive emotions and its connection with trait resilience in the realm of friendships.

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