Systematic training of muscle strengthening began in the world of competitive sport, nowaday
it is recommended for all individuals because of its several health benefits. On the market are
many devices for training that many users, even with specific academic education training,
may have their doubts about what is best for their purposes.
In order to avoid the problems above described, in this systematic review it presents the
scientific basis of the functioning of the vast majority of existing devices on the market. They
are grouped according to the mechanism of resistance: (1) free weight, (2) machines
dependent on the gravity, (3) machines equipped with hydraulic systems, (4) machines
equipped with pneumatic systems, (5) water resistance (6), elastic resistance, (7) manual
resistance, (8) and electronically controlled devices (9) other (unstable devices, flywheels,
vibratory machines and bodyblade).
Key words. Strength curves, torque, sticking point, acceleration.