The resistance increasing throughout the range of motion - a demonstration

With free weights and most exercise equipment resistance is constantthroughout the range of motion. You are limited to lifting whatever amount you can lift through the sticking point, that point where you are at a mechanical disadvantage. That will be the hardest part of the movement; the reminder of the repetition will be relatively easier.

With variable resistance the weight changes throughout the range. It should be lighter at the sticking point and heavier in the range where one has a mechanical advantage. Watch the numbers on the scale change in the video. This feature makes for safer more productive exercise. MedXstrength training equipment has variable resistance. We have extensive lines of MedX equipment both our Austin Fitness Trainers and New Orleans Personal Trainers locations.

Avoiding hyper-extending the knees on the leg press

Most leg press machines provide movement in a straight line. With straight line movement there is more shearing force at the end point of the movement, and if one locks out at the end point there is greater potential for hyper-extending the knee. As an example see here (warning graphic).  At Austin Fitness Trainers and at New Orleans Fitness Trainers  we use MedX equipment. The MedX leg press provides an arcing range of motion similar to the rotation of the knee, and it can be set so that there is no locking out at the end point.