Knee Extensor Static Strength Variations as a Function of Fibula-Femoral Angle

2015 ◽  
pp. 197-201
Author(s):  
A. Linford ◽  
G. Rarick
Keyword(s):  
Knee Extensor ◽  
Static Strength

ALCOA 7150-T7751 and T77511

Alloy Digest ◽  
2015 ◽  
Vol 64 (4) ◽  
Keyword(s):  
Compressive Strength ◽  
Corrosion Resistance ◽  
Tensile Properties ◽  
High Strength ◽  
Static Strength ◽  
Corrosion Resistant ◽  
Overaged Condition

Abstract This producer has pioneered the development of the -T77 temper, a high strength corrosion resistant temper for Alloy 7150 plate and extrusions. Alloy 7150-T77 provides weight savings opportunities in structure governed by static strength requirements but where "overaged" condition corrosion resistance is required. This datasheet provides information on composition, tensile properties, and compressive strength. It also includes information on corrosion resistance as well as forming. Filing Code: Al-442. Producer or source: Alcoa Mill Products Inc..

scholarly journals The use of flat-ended projectiles for determining dynamic yield stress - II. Tests on various metallic materials

1948 ◽  
Vol 194 (1038) ◽  
pp. 300-322 ◽  
Keyword(s):  
Yield Strength ◽  
Dynamic Strength ◽  
Soft Materials ◽  
Static Strength ◽  
Compressive Yield Strength ◽  
Dynamic Tests ◽  
Pure Lead ◽  
Permanent Strain ◽  
Yield Values ◽  
Static Conditions

A description is given of the experimental technique devised to apply the method outlined theoretically in part I to the measurement of the dynamic compressive yield strength of various steels, duralumin, copper, lead, iron and silver. A polished piece of armour steel was employed as a target, and cylindrical specimens were fired at it at various measured velocities from Service weapons. The distance between the weapon and target was made short to ensure normal impact, and apparatus was devised for the precise measurement of striking velocity over this short range. The dynamic compressive yield strength was computed from the density of the specimen, the striking velocity, and from measurements of the dimensions of the test piece before and after test. Details are given of the accuracy of the various measurements, and of their effect on the values of yield strength. The method was found to be inaccurate at low and high velocities. For instance, with mild steel, satisfactory results were only obtainable within the range 400 to 2500 ft. /sec. The range of velocities within which satisfactory results could be obtained varied with the quality of the material tested, soft metals giving results within a much lower range than that necessary for harder materials. Because of its failure at low velocities, the method could not be employed to bridge the gap between static and dynamic tests. The rate of strain employed in the dynamic tests could not be measured, but was estimated to be of the order of 10,000 in. /in. /sec. With the materials tested little change of dynamic strength occurred within the range of striking velocities employed, probably because the rate of strain did not vary to any great extent with the striking velocity. Within the range of weapons available, that is, from a 0·303 in. rifle up to a 13 pdr. gun (calibre 3·12 in.), little change of dynamic strength occurred with alteration of the initial dimensions of the specimens, probably because the corresponding change of rate of strain was not large. In general, the dynamic compressive yield strength S was greater than the static strength Y represented by the compressive stress giving 0·2% permanent strain. For steels of various types, regardless of chemical composition and heat treatment, there was a relation between S / Y and the static strength Y , the ratio decreasing from approximately 3 when Y was 20 tons/sq. in. to 1 when Y was 120 tons/sq. in. A similar relation occurred with duralumin, S / Y varying from 2·5 at Y = 8 tons/sq. in. to 1·4 at Y = 25 tons/sq. in. Dynamic compressive yield values were obtained for soft materials such as pure lead, copper and Armco iron, which, under static conditions, gave no definite yield values. A plot of the unstrained length of the specimen X , expressed as X / L (where L = initial overall length), versus the final overall length L 1 , expressed as L 1 / L , was made for the various materials. Any specified value of X / L was associated with greater values of L 1 / L for the more ductile materials, such as copper and lead, than for the brittle materials, such as armour plate and duralumin.

scholarly journals Efficacy of cardiac rehabilitation with motion assistance from wearable cyborg hybrid assistive limb in patients with chronic heart failure: a randomized controlled trial

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
H Watanabe ◽  
A Koike ◽  
H Kato ◽  
L Wu ◽  
K Hayashi ◽  
...  
Keyword(s):  
Heart Failure ◽  
Chronic Heart Failure ◽  
Cardiac Rehabilitation ◽  
Exercise Therapy ◽  
Knee Extensor ◽  
Control Group ◽  
Cardiac Events ◽  
Rehabilitation Programs ◽  
Sit To Stand ◽  
Knee Extensor Strength

Abstract Background Recent Cochrane Systematic Review suggested that the participation in cardiac rehabilitation is associated with approximately 20% lower cardiovascular mortality and morbidity. Exercise therapy is the key component of cardiac rehabilitation programs. In recent years, innovative technologies have been introduced into the field of rehabilitation, and a typical example is the wearable cyborg Hybrid Assistive Limb (HAL). The wearable cyborg HAL provides motion assistance based on detection of bioelectrical signals on the skin surface when muscle forces are generated. The lumbar-type HAL is expected to expand the therapeutic options for severe cardiac patients who have difficulty in performing usual cardiac rehabilitation programs, such as bicycle pedaling or walking. Purpose We aim to compare the efficacy of exercise therapy performed with motion assistance from a lumbar-type HAL versus conventional training (sit-to-stand exercise without HAL) in patients with chronic heart failure. Methods This clinical trial is a randomized, non-blinded, and controlled study. Twenty-eight heart failure patients (73.1±13.8 years) who have difficulty in walking at the usual walking speed of healthy subjects were randomly assigned to 2 groups (HAL group or control group) with a 1:1 allocation ratio and performed sit-to stand exercise either with HAL or without HAL for 5 to 30 minutes once a day, and 6 to 10 days during the study period. The brain natriuretic peptide (BNP), isometric knee extensor strength, standing ability (30-seconds chair-stand test: CS-30), short physical performance battery (SPPB) and 6-minute walking distance (6MWD) were measured before and after the completion of cardiac rehabilitation. Cardiac events such as death, re-hospitalization, myocardial infarction and worsening of angina pectoris and heart failure during 1 year after discharge were evaluated. Results There was no significant difference in the number of days of exercise therapy between the two groups. BNP, SPPB and 6MWD were improved in both groups. In the HAL group, the isometric knee extensor strength (0.29±0.11 vs 0.35±0.11 kgf/kg, p=0.003) significantly improved and CS-30 (5.5±5.1 vs 8.2±5.3, p=0.054) tended to improve. However, in the control group, either the isometric knee extensor strength (0.35±0.11 vs 0.36±0.14 kgf/kg, p=0.424) or CS-30 (6.0±4.3 vs 9.2±6.2, p=0.075) did not significantly change. HAL group showed significantly more improvement in the isometric knee extensor strength than control group (p=0.045). Cardiac events occurred in 20% in the HAL group and 43% in the control group. Conclusion The improvement in isometric knee extensor strength with the assistance from lumbar-type HAL suggests that exercise therapy using this device may be useful in chronic heart failure patients with flail or sarcopenia, a strong poor prognostic factor in these patients. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): This work was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Science, and Culture of Japan (JSPS KAKENHI grant number JP17K09485) and funded by the ImPACT Program of the Council for Science, Technology and Innovation (Cabinet Office, Government of Japan) (grant number 2017-PM05-03-01).

scholarly journals Running Biomechanics Before Injury and 1 Year After Anterior Cruciate Ligament Reconstruction in Division I Collegiate Athletes

2021 ◽  
pp. 036354652110266
Author(s):  
Keith A. Knurr ◽  
Stephanie A. Kliethermes ◽  
Mikel R. Stiffler-Joachim ◽  
Daniel G. Cobian ◽  
Geoffrey S. Baer ◽  
...  
Keyword(s):  
Anterior Cruciate Ligament ◽  
Cruciate Ligament ◽  
Knee Extensor ◽  
Collegiate Athletes ◽  
Treadmill Running ◽  
Division I ◽  
P Values ◽  
Peak Knee ◽  
Anterior Cruciate ◽  
Running Biomechanics

Background: Preinjury running biomechanics are an ideal comparator for quantifying recovery after anterior cruciate ligament (ACL) reconstruction (ACLR), allowing for assessments within the surgical and nonsurgical limbs. However, availability of preinjury running biomechanics is rare and has been reported in case studies only. Purpose/Hypothesis: The purpose of this study was to determine if running biomechanics return to preinjury levels within the first year after ACLR among collegiate athletes. We hypothesized that (1) surgical knee biomechanics would be significantly reduced shortly after ACLR and would not return to preinjury levels by 12 months and (2) nonsurgical limb mechanics would change significantly from preinjury. Study Design: Cohort study; Level of evidence, 2. Methods: Thirteen Division I collegiate athletes were identified between 2015 and 2020 (6 female; mean ± SD age, 20.7 ± 1.3 years old) who had whole body kinematics and ground-reaction forces recorded during treadmill running (3.7 ± 0.6 m/s) before sustaining an ACL injury. Running analyses were repeated at 4, 6, 8, and 12 months (4M, 6M, 8M, 12M) after ACLR. Linear mixed effects models were used to assess differences in running biomechanics between post-ACLR time points and preinjury within each limb, reported as Tukey-adjusted P values. Results: When compared with preinjury, the surgical limb displayed significant deficits at all postoperative assessments ( P values <.01; values reported as least squares mean difference [SE]): peak knee flexion angle (4M, 13.2° [1.4°]; 6M, 9.9° [1.4°]; 8M, 9.8° [1.4°]; 12M, 9.0° [1.5°]), peak knee extensor moment (N·m/kg; 4M, 1.32 [0.13]; 6M, 1.04 [0.13]; 8M, 1.04 [0.13]; 12M, 0.87 [0.15]; 38%-57% deficit), and rate of knee extensor moment (N·m/kg/s; 4M, 22.7 [2.4]; 6M, 17.9 [2.3]; 8M, 17.5 [2.4]; 12M, 16.1 [2.6]; 33%-46% deficit). No changes for these variables from preinjury ( P values >.88) were identified in the nonsurgical limb. Conclusion: After ACLR, surgical limb knee running biomechanics were not restored to the preinjury state by 12M, while nonsurgical limb mechanics remained unchanged as compared with preinjury. Collegiate athletes after ACLR demonstrate substantial deficits in running mechanics as compared with preinjury that persist beyond the typical return-to-sport time frame. The nonsurgical knee appears to be a valid reference for recovery of the surgical knee mechanics during running, owing to the lack of change within the nonsurgical limb.

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