BACKGROUND: Muscle strength depends among other factors on its length, i.e., the angular position of the joint it spans. However, these relationship is often neglected in the construction of training machines.
OBJECTIVE: The aim of this study was to verify the effectiveness of a variable-cam during strength training.
METHODS: Thirty-two men divided into two groups participated in an 8-week intensive strength training of elbow flexors. One group (C) trained on a machine with a cam developed in the shape corresponding to the strength change characteristics of flexor muscles as a function of the angular position in the elbow joint. The second group (D) trained on a machine with a disc plate. The effects of the training were evaluated on the basis of changes in the value of PT measured under isokinetic conditions, anthropometric parameters, and CK activity.
RESULTS: After the end of the training, a significant increase in the values of the PT and anthropometric parameters were observed only in group C. Weekly changes of CK activity appeared only in the group exercising with a cam, while in the group exercising on the machine with a disc plate, the two-day rest turned out to be too short for the elimination of the CK molecules from the blood to occur.
CONCLUSIONS: Strength training using a machine with a muscle-specific adjusted cam is especially effective in the case of the elbow flexors.
