Apabila anda bersenam, otot anda melakukan tugasnya dengan menarik tulang anda, yang berfungsi sebagai tuil untuk mencipta pergerakan. Levers boleh diklasifikasikan sebagai kelas pertama, kedua atau ketiga, menurut Kinesiology Sistem Muskuloskeletal: Yayasan untuk Pemulihan .
Kebanyakan senaman menggunakan tuil kelas ketiga, yang paling biasa di dalam badan, tetapi beberapa menggunakan tuil pertama dan kelas kedua.
Apa itu Tuas?
Tuas adalah struktur yang tegar, seperti bar atau tulang, yang berputar di sekeliling paksi, yang disebut fulcrum. Dalam badan anda, otot membekalkan tenaga untuk menggerakkan tulang anda, yang berputar di sekitar lubang yang terletak di sendi anda.
Berat otot anda perlu diatasi - sama ada anggota badan, seluruh badan atau berat luaran seperti barbell atau bodoh - dipanggil "daya rintangan, " atau hanya "rintangan." Levers dikelaskan mengikut penempatan relatif fulcrum, rintangan dan daya.
Contoh Pertama Tuas Kelas
Dalam tuas kelas pertama, tumpuan terletak di antara rintangan dan daya. Seesaw adalah tuas kelas pertama. Tuas kelas pertama dalam badan jarang berlaku, dan beberapa latihan menggunakannya.
Examples, however, are exercises that require elbow extension, such as dumbbell triceps extensions, cable triceps push-downs and triceps dips. In each of these exercises, the elbow joint serves as the fulcrum, which lies between the resistance and the force applied by the triceps muscle behind the elbow.
For the triceps dips, you can use a bench at the gym or your own staircase. Sit on the bench and place your hands beside your hips with your fingers hang over the side, says ACE Fitness. With either outstretched legs or bent knees and your feet flat on the floor, lift your hips off the surface and use the strength of your arms to lower down. Hold. Rise back up and repeat 10 times.
Second-Class Levers
Second-class lever examples in the body are also fairly rare. In a second-class lever, the resistance lies between the fulcrum and the force, as in a wheelbarrow. Exercises that require plantarflexing the ankle, such as seated or standing calf raises, employ a second-class lever.
In a calf raise, the resistance — the weight of the body — is positioned between the fulcrum at the toes and balls of the feet, and the force, which is applied by the calf muscles pulling on the heel. Push-ups also utilize a second-class lever.
A calf raise is performed by balancing on your toes on a surface higher than the floor. Lower your heels and then rise up onto your toes. Hold onto a bar or the wall, says ExRx.net, to keep your balance.
Third-Class Levers
ExRx.net notes that most levers in the body are third-class levers, in which force is applied between the fulcrum and the resistance. A shovel is an example. Biceps curls employ a third-class lever, with the force being exerted by the bicep muscle between the fulcrum at the elbow joint and the weight in your hands.
Other examples include seated and lying hamstring curls, seated leg extensions, dumbbell flies, and shoulder dumbbell front and lateral raises.
For the lateral raise, hold a dumbbell in each hand with your palms facing toward your hips. Exhale and raise the dumbbells out to the side until they reach shoulder height. Inhale and lower your arms.
