Even though we have divided the classification muscular contractions into three areas - the reality looks more complex.
In reality, we have 2 types of muscle contractions, Isometric & Isotonic.
Isotonic, and Isometric have many different resulting meanings in science - but in this purpose, we break it down into two definitions...
Isometric Muscular Contraction: A tensioning of muscle fibres resulting in a change of muscular length. (longer or shorter)
Isotonic Muscular Contraction: A tensioning of muscle fibres resulting in NO change of muscular length.
Isometric muscular contractions are the most obvious types - because they influence the limbs of the horse usually in very visually obvious ways. They contract, and they extend limbs through flexion & extension of the joints.
Isotonic Muscular contractions are the silent storms of activity….they are busy stabilising joint spaces & generating power to be used in subsequent movements. They are often activated pre-movement, or pre flight response. We can refer to them as the Dwayne Johnson of the motivational scrapbooking movement….
In a concentric contraction, the muscle tension rises to meet the resistance then remains stable as the muscle shortens.
During eccentric contraction, the muscle lengthens as the resistance becomes greater than the force the muscle is producing.
During changes to joint angles that either result in a reduction of angle (flexion) or an increase change of angle (extension), some of the associated muscles will be in eccentric contraction, and other muscles will be in concentric contraction. These roles of muscle tissue are defined as agonist, or antagonist.
For example, flexion of the horse's hip (coxofemoral joint) requires a concentric contraction of the Tensor fasciae latae, superficial gluteal, pectineous, sartorius, (agonist muscles) whereas the Quadricep femoris, biceps femoris femoris, semitendonosus, semimembranosus etc (antagonist responding muscles) lengthens in an eccentric action.
Muscle contraction is controlled by muscle spindles & Golgi tendon organs
which are both peripheral neural receptors which work together through reflex action to regulate muscular tension with the tendon & muscle fibres.
Muscular contraction in biomechanical systems to facilitate skeletal movement is complex, and always is a result of a collaborative team of activated systems.
It starts with the deep, stabilising muscles such as the vertebral multifidus, and the psoas for example (there are many more), then antagonistic muscles also contract at the same time to stabilise joint spaces with feedback from the muscle spindles (both intrafusal & extrafusal) & the golgi tendon organs, and then lastly the primary movement inciting muscle groups are activated, resulting in the more obvious, spatially influential changes.
Once the muscular spindles have started to acquire & transmit information, the central nervous system uses this to calculate the motor patterns & spatial positioning of the limbs.
This information is vital to maintain posture, the stability within the gait and also motor control through the movement...thanks for that demonstration Dwayne.
So all of this happens in an organised, progressive chaos of feedback loops to result in stabilisation in the face of gravity, torque as well as at the same time generating propulsion, protection to joint spaces and preservation tissues.
#biologymatterstothehorse #horsewelfare #sustainableequitationandmobility #sustainableequinemobility #eventersofinstagram #dressageridersofinstagram #horseridersofinstagram #equinemovement #horseridersoffacebook #eventing #horsesoffacebook #equinewellbeing #biologymatters #carriagedriving #horsefitness #equinebiomechanics #movementistherapy #movementishealing #horsebiomechanics #horses #horsetrainersofinstagram #horsesofinstagram #equinetherapy #horsetrainer #horsetrainerlife #horsetrainers #thoroughbredsofinstagram #resetequinesem
Comments