There were also no
differences during a 5 year follow-up between both groups on measures of subjective and
functional outcomes [47]. Specificity of training should not be ignored when prescribing
exercise for PFPS patients. Augustsson [48] found that healthy subjects training with the
barbell squat had significantly greater increases in both a squat 3RM and jump test
compared to the open kinetic trained group. Although not directly affecting PFPS, it
should also be noted that open kinetic chain exercises tend to produce significantly more
anterior displacement of the tibia than closed kinetic chain exercises which may place
strain on the ACL [49, 50]. Knowledge of these issues may not only help rehabilitation
but also prevention of knee injuries.