Estimates of individual muscle power production in normal adult walking

Your doctor with any brains at all should be able to compare your stroke affected hip muscles to normal and prescribe stroke protocols to bring those muscles up to full strength. If your doctor can't do that, you need to call the hospital president and ask why such incompetency is allowed.  This is so fucking simple. You take the objective diagnosis of stroke deficits and prescribe the exact stroke protocols that will correct those deficits. If your doctor and hospitals aren't doing that you need to have them all fired.
https://jneuroengrehab.biomedcentral.com/articles/10.1186/s12984-017-0306-2

• Ross A. BogeyEmail authorView ORCID ID profile and
• Lee A. Barnes

Journal of NeuroEngineering and Rehabilitation201714:92

https://doi.org/10.1186/s12984-017-0306-2

©  The Author(s). 2017

Received: 2 February 2017

Accepted: 4 September 2017

Published: 11 September 2017

Abstract

Background

The purpose of this study was to determine the contribution of individual hip muscles to the net hip power in normal adult self-selected speed walking. A further goal was to examine each muscle’s role in propulsion or support of the body during that task.

Methods

An EMG-to-force processing (EFP) model was developed which scaled muscle-tendon unit (MTU) force output to gait EMG. Active muscle power was defined as the product of MTU forces (derived from EFP) and that muscle’s contraction velocity. Passive hip power was estimated from passive moments associates with hip position (angle of flexion (extension)) and the hip’s angular velocity. Net hip EFP power was determined by summing individual active hip muscle power plus the net passive hip power at each percent gait cycle interval. Net hip power was also calculated for these study participants via inverse dynamics (kinetics plus kinematics, KIN). The inverse dynamics technique – well accepted in the biomechanics literature – was used as a “gold standard” for validation of this EFP model. Closeness of fit of the power curves of the two methods was used to validate the model.

Results

The correlation between the EFP and KIN methods was sufficiently close, suggesting validation of the model’s ability to provide reasonable estimates of power produced by individual hip muscles. Key findings were that (1) most muscles undergo a stretch-shorten cycle of muscle contraction, (2) greatest power was produced by the hip abductors, and (3) the hip adductors contribute to either hip adduction or hip extension (but not both).

Conclusions

The EMG-to-force processing approach provides reasonable estimates of individual hip muscle forces in self-selected speed walking in neurologically-intact adults.

Background

The role of individual hip muscles in normal walking has not been fully described. A more complete understanding of each muscle’s role could be established by knowledge of that muscle’s force output and power generation. However, direct measurements of muscle force has been obtained for only a few lower extremity muscles (i.E. Achilles tendon [1, 2]), and the techniques used to directly record muscle forces – even when possible – are not practical in a clinical environment. Muscle power is related to muscle force, in that it is the product of force output and muscle-tendon unit (MTU) contraction velocity. Joint power – that is, the power produced by synergistic muscles – may be used to establish the capacity of muscle groups to generate or restrain movement [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. Concentric power typically produces motion, while negative power implies motion restraint. A possible confound is that the presence of muscle power has been used as a proxy for muscle activity, yet studies of amputee locomotion [13] demonstrate non-zero power at the prosthetic ankle. Further, isometric contractions have zero power, due to a contraction velocity of zero. Nonetheless, the power produced by any muscle cannot be directly determined. Hence other methods are required.

An impediment to easy determination of muscle power – and the potential role of individual hip muscles – is that the hip has more muscles than are necessary to perform basic movements. This overabundance of muscles leads to statistical indeterminacy (more unknown muscle forces than solution set of equations). Power calculation approaches thus are based on inverse dynamics techniques. This method solves the actuator-redundancy problem. However, conventional power analysis cannot define the unique power contribution of a single muscle, except in uncommon cases where only a single muscle is responsible for the observed movement. Co-contraction of agonists and antagonists is a further confound. As a result there may not be a direct link between a muscle’s power output (via inverse dynamics techniques) and that muscle’s true role in gait. These factors show that the muscle power estimates from inverse dynamics can include muscle force, joint angular velocities and other, undefined variables.

Neuromuscular modeling techniques have produced reasonable estimates of in vivo ankle muscle power [14]. It was the purpose of this study to examine if those techniques could be applied to at the more proximal hip joint to determine individual hip muscle power production in normal, self-selected-speed walking.

More at link. Your doctor will need to solve this equation;

The post-processed EMG profile ε(t) was defined byε(t)=γ(ρ1E(t)+ρ2E(t−1)+ρ3E(t−2)+ρ4ε(t−1)+ρ5ε(t−2))