If you do strength training to improve your sports performance or your general physical functioning in every day life, you can forget about leg-presses. Rather than wasting your time on the leg-press machine you would do better to concentrate on squats. We base this bold statement on a study that the German sports scientist Klaus Wirth published in the Journal of Strength and Conditioning Research.
The researchers divided almost 80 students into three groups. The first group, the control group, did nothing for eight weeks.
A second group of students trained their legs on a leg-press machine twice a week for eight weeks; and a third group trained their legs by doing squats. The two training groups used the same training schedule.
The students who had done squats boosted their maximal strength while squatting by about a quarter. The students who had trained on the leg-press also boosted their maximal strength by a quarter while doing leg presses.
The researchers measured the amount of isometric strength the subjects could generate on a kind of leg-extension machine, before and after the training period. They also got the students to do jump squats and countermovement jumps so that they could measure – put simply – the speed the students were capable of developing.
The subjects who had done squats made progress in all three areas. The subjects that had trained on the leg-press machine made virtually no progress at all.
So the strength you develop by squatting results in and increase in strength and speed when doing real life movements. The strength that is built up by doing leg-press exercises does not have the same effect.
“The data suggest a large influence of the selection of training exercise on performance improvement – at least short-term”, wrote the researchers. “The squat was shown to be the more effective training exercise. Therefore, it should be preferred to the leg press.”
“This holds true especially in the special stage before competition because of the better transfer effects on jumping performance but must also be considered in the context of long-term development of speed-strength performance.”