The addition of 35%
body weight increased PFJRF up to 45% of the unloaded trials. In a similar study,
Salem [24] examined five intercollegiate female athletes squatting to depths of 70°, 90°,
and 110° utilizing 85% of their 1 repetition max (1RM). No differences were found in
net peak knee extensor moments or PFJRF at the three depths. In contrast, Dahlkvist
[25] generally found increasing PFJRF as greater depth was achieved in an
unconventional squat where the heels do not remain on the ground. It is clear that much
of the difficulty in interpretation of the current research relating to the squat exercise is in
the large amount of variation found in the techniques and loads utilized.