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An Investigation of the Relationship between Hip Extension Torque, Hip Extension Velocity, and Muscle Activation

David Hawkins and Mark Smeulders

The purpose of this study was to determine if the characteristic Hill model, used to describe me force–velocity relationship for isolated tetanically stimulated muscle, could be modified and used to describe me torque–velocity behavior of me hip for maximally and submaximally stimulated hip extensor muscles. Fourteen subjects performed hip extension movements at effort levels of 100%, 70%, and 40% of a maximum isometric effort. A solenoid provided isometric resistance to hip extension. Once the desired effort level was achieved, as indicated by me isometric force, the solenoid released and me hip moved against an opposing elastic resistance equal to 75%, 50%, 25%, and 0% of the specified effort level. An electrogoniometer quantified hip angle. Hip velocity was determined by numerically differentiating the angle data. Torque-velocity-activation (or effort level) data were determined for each trial. Model parameters were determined to give me best fit to the data for each subject. Average parameter values were determined for each gender and for the entire group. The modified Hill-type model, T m = (T max · AK 1 · ω)/(K2 · ω + 1), accurately describes me relationship between joint torque (T m), maximum isometric joint torque (T max), joint velocity (ω), and muscle activation level (A) for subject-specific parameters (K 1 and K 2), but not for parameters averaged across genders or the entire group. Values for T max, K 1, and K 2 ranged from 90 to 385 Nm, 6.1 to 47.9 Nms, and 0.030 to 0.716 s, respectively.

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Validity and Reliability of the Kinvent Handheld Dynamometer in the Athletic Shoulder Test

Margie Olds, Sally McLaine, and Nico Magni

Shoulder strength testing is an important contribution to objectively inform clinical decisions when returning an athlete to sport after a shoulder injury. 1 In the assessment of shoulder muscle strength, objective measurement of peak force and torque production can be used in shoulder positions

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Effects of a 12-Week Chronic Stretch Training Program at Different Intensities on Joint and Muscle Mechanical Responses: A Randomized Clinical Trial

Natália Barros Beltrão, Camila Ximenes Santos, Valéria Mayaly Alves de Oliveira, André Luiz Torres Pirauá, David Behm, Ana Carolina Rodarti Pitangui, and Rodrigo Cappato de Araújo

significantly affect changes in range of motion (ROM), 2 , 3 passive torque response, 3 and muscle architecture, 4 there are few studies investigating stretch intensity effects within a chronic flexibility training program. There is conflict regarding stretching intensity in the literature, with some acute

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Whole-Body Vibration on Performance of Quadriceps After ACL Reconstruction: A Blinded Randomized Controlled Trial

Karinna Sonálya Aires da Costa, Daniel Tezoni Borges, Liane de Brito Macedo, Caio Alano de Almeida Lins, and Jamilson Simões Brasileiro

limbs and for balance after a protocol using a frequency of 30 Hz and amplitude of 10 mm. They suggest that this improved performance immediately after the vibrating stimulus might be related to an increase in stretch reflex sensitivity. 13 Stewart et al 14 also found increased isometric peak torque

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The Reliability and Validity of a Novel Ankle Isometric Plantar Flexion Strength Test

Takumi Kobayashi, Takeshi Mizota, Kana Kon, Miku Kasaya, Shogo Miyabe, Tomo Shindome, and Kousuke Ishibashi

) was used for statistical analysis, and a P value <.05 was considered significant. Experiment 2 The intraexaminer and interexaminer reliabilities of the PFBT and the isometric ankle PF torque were compared between positive and negative PFBT cases in healthy adults to verify the concurrent validity in

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Discriminatory Ability of Lower-Extremity Peak Torque and Rate of Torque Development in the Identification of Older Women With Slow Gait Speed

Mary Hellen Morcelli, Dain Patrick LaRoche, Luciano Fernandes Crozara, Nise Ribeiro Marques, Camilla Zamfolini Hallal, Mauro Gonçalves, and Marcelo Tavella Navega

gait speed. 7 , 8 Poor lower limb strength has been associated with slow gait speed and the likelihood of falling, making it an important predictor of functional status in older adults. 9 – 12 The association exists because joint torques at the hip, knee, and ankle are summed in a coordinated fashion

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Associations Between Lower Limb Isometric Torque, Isokinetic Torque, and Explosive Force With Phases of Reactive Stepping in Young, Healthy Adults

Tyler M. Saumur, Jacqueline Nestico, George Mochizuki, Stephen D. Perry, Avril Mansfield, and Sunita Mathur

strength can be defined as the force-generating capacity of the muscle 4 and can be quantified using various measures of force or torque. Muscle power is the mechanical work performed by the muscle over time and the muscle’s ability to produce high-velocity movements. 5 Balance control, strength, and

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The Acute Effects of Fast-Paced Walking on Isometric Peak Torque and Rate of Torque Development in Regularly Exercising and Inactive Older Women

Ty B. Palmer, Jarrod Blinch, Ahalee C. Farrow, Chinonye C. Agu-Udemba, and Ethan A. Mitchell

et al., 2016 ; Pereira et al., 2018 ). Such fatigue effects combined with substantial age-related decreases in muscle strength and balance may impair locomotor function and increase the risk of falls and fall-related injuries in older individuals ( Morrison et al., 2016 ). Strength-based torque

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Assessment of Bilateral Asymmetry in Cycling Using a Commercial Instrumented Crank System and Instrumented Pedals

Rodrigo R. Bini and Patria A. Hume

The accuracy of commercial instrumented crank systems for symmetry assessment in cycling has not been fully explored. Therefore, the authors’ aims were to compare peak crank torque between a commercial instrumented crank system and instrumented pedals and to assess the effect of power output on bilateral asymmetries during cycling. Ten competitive cyclists performed an incremental cycling test to exhaustion. Forces and pedal angles were recorded using right and left instrumented pedals synchronized with crank-torque measurements using an instrumented crank system. Differences in right (dominant) and left (nondominant) peak torque and asymmetry index were assessed using effect sizes. In the 100- to 250-W power-output range, the instrumented pedal system recorded larger peak torque (dominant 55–122%, nondominant 23–99%) than the instrumented crank system. There was an increase in differences between dominant and nondominant crank torque as power output increased using the instrumented crank system (7% to 33%) and the instrumented pedals (9% to 66%). Lower-limb asymmetries in peak torque increased at higher power-output levels in favor of the dominant leg. Limitations in design of the instrumented crank system may preclude the use of this system to assess peak crank-torque symmetry.

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Normalizing Lower Extremity Strength Data for Children, Adolescents, and Young Adults with Cerebral Palsy

Tishya A. L. Wren and Jack R. Engsberg

The traditional method for normalizing quantitative strength data is to divide force or torque by body mass. We have previously shown that this method is not appropriate for able-bodied children and young adults and that normalization using allometric scaling is more effective. The purpose of the current study was to evaluate the effectiveness of applying existing normalization equations for lower extremity strength to children, adolescents, and young adults with cerebral palsy (CP) and, if appropriate, to develop CP-specific normalization equations using allometric scaling. We measured the maximum torque generated during hip abduction/adduction, knee extension/flexion, and ankle dorsiflexion/plantar flexion in 96 subjects with spastic diplegia CP ages 4–23 years. Traditional mass normalization (Torque/Mass1.0) and allometric scaling equations from children without disability (Torque/Mass1.6 for hip and knee; Torque/Mass1.4 for ankle) were not effective in eliminating the influence of body mass. Normalization using CP-specific allometric scaling equations was effective using both muscle-specific and common (Torque/Mass0.8 for ankle plantar flexors; Torque/Mass1.4 for all others) scaling relationships. For the first time, normalization equations have been presented with demonstrated effectiveness in adjusting strength measures for body size in a group of children, adolescents, and young adults with CP.