The benefits derived from exercising one's hips, thighs, hamstrings, calves, and lower back are sufficiently important and well-known not to require elaboration here. However, conventional machinery which provides this beneficial exercise has been woefully deficient in assuring that the exerciser can adapt and vary the machine according to physical demands, or immediately disengage the machine should it be necessary. Prior art devices of which applicant is aware include conventional barbells which do not assure the total isolation of the muscle to be developed, and machines in which the back support is disposed upon a substantially triangular framework including a weight cage, a base and the hypotenuse of a triangle upon which the back support lies that is not adjustable relative to the trackway. Clearly, the situation may arise in which one wishes to disengage the machine prematurely relative to a complete repetition of the exercise (for example due to excessive weight, or a muscle failure, etc.); and this has been one difficulty in performing the exercise.
Further, it may be desirable to perform the exercise in which the back portion of the thigh does not always need to be folded at the knee to such an extent that it almost touches the heels of one's shoes, and a prevalent problem is to provide a reliable stop mechanism so that the range of the exercise and its motion can be limited. This is particularly true in people that are recovering from knee injuries.