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Kipping pull-ups have lower muscle activation in the upper body but greater activation in the lower body and core; it is possible to perform them faster and complete more repetitions before encountering upper-body fatigue. [14] Kipping pull-ups are considered high risk for injury and are a major cause of shoulder injury in CrossFit athletes. [15]
The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).
The action potential passes along the cell membrane causing the cell to contract, therefore the activity of the sinoatrial node results in a resting heart rate of roughly 60–100 beats per minute. All cardiac muscle cells are electrically linked to one another, by intercalated discs which allow the action potential to pass from one cell to the ...
There are three distinct types of muscle: skeletal muscle, cardiac or heart muscle, and smooth (non-striated) muscle. Muscles provide strength, balance, posture, movement, and heat for the body to keep warm. [3] There are more than 600 muscles in an adult male human body. [4]
The majority of this type of muscle tissue is found in the digestive and urinary systems where it acts by propelling forward food, chyme, and feces in the former and urine in the latter. Other places smooth muscle can be found are within the uterus, where it helps facilitate birth, and the eye, where the pupillary sphincter controls pupil size. [3]
Parachute mitral valve occurs when all the chordae tendineae of the mitral valve attach to a single papillary muscle. [9] [10] [11] This causes mitral valve stenosis at an early age. [10] It is a rare congenital heart defect. [11] Although it often causes mitral insufficiency, it may not present any symptoms. [10]
Troponin is found in both skeletal muscle and cardiac muscle, but the specific versions of troponin differ between types of muscle. The main difference is that the TnC subunit of troponin in skeletal muscle has four calcium ion-binding sites, whereas in cardiac muscle there are only three.
The heart muscle may become inflamed in a condition called myocarditis, [46] most commonly caused by a viral infection [47] but sometimes caused by the body's own immune system. [48] Heart muscle can also be damaged by drugs such as alcohol, long standing high blood pressure or hypertension, or persistent abnormal heart racing. [49]