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David Hawkins and Mark Smeulders

The purpose of this study was to determine if the Hill model, used to describe the force-velocity relationship for isolated tetanically stimulated muscle, could be modified and used to describe the torque-velocity behavior of the knee for maximally and submaximally stimulated quadriceps and hamstrings muscles. Fourteen subjects performed both knee flexion and extension movements at 100%, 70%, and 40% of maximum isometric effort. For each effort level, the knee was allowed to move against resistances equal to 75%, 50%, 25%, and 0% of the specified effort level. An electrogoniometer quantified knee angle. Knee velocity was determined by numerically differentiating the joint angle data. Torque-velocity-activation (or effort level) data were determined for each trial. Model parameters were determined to give the 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 accurately described the relationship between torque, velocity, and muscle activation level for subject-specific parameters but not for parameters averaged across genders or the entire group.

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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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Andreas Apostolidis, Vassilis Mougios, Ilias Smilios, Johanna Rodosthenous and Marios Hadjicharalambous

submaximally stimulated mouse EDL (fast) and soleus (slow) muscle . J Appl Physiol . 2012 ; 112 : 64 – 71 . PubMed ID: 21979804 doi:10.1152/japplphysiol.00801.2011 21979804 10.1152/japplphysiol.00801.2011 29. Ali A , O’Donnell J , Foskett A , Rutherfurd-Markwick K . The influence of caffeine

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Sunita Potgieter, Hattie H. Wright and Carine Smith

the endurance of maximally and submaximally stimulated mouse soleus muscle . Journal of Physiological Sciences, 63 ( 2 ), 125 – 132 . PubMed ID: 23292763 doi:10.1007/s12576-012-0247-2 10.1007/s12576-012-0247-2 Terry , P.C. , Lane , A.M. , & Fogarty , G.J. ( 2003 ). Construct validity of