Abstract:
Background: Long distance runners commonly complain from patellofemoral pain syndrome (PFPS)
that limits their performance and return to sport. Abnormal neuromuscular control of the quadriceps
has been demonstrated to cause patellar mal-tracking and hence PFPS. Changes in muscle morphology
and neural activity have a role in neuromuscular changes, a key contributor to either primary or
secondary injuries. Poor landing mechanics, impaired postural control, as well as changed peripheral
muscle activation are all clinical manifestations of neuromuscular control deficiencies caused by
central nervous system defects that have a deleterious effect on the contractile characteristics of skeletal
muscle. Objectives: The purpose of this study was to investigate the correlation between contractile
properties of quadriceps muscle and functional performance in long distance runners with PFPS. Study
design: Cross-sectional study. Methods: Thirty runners were recruited form multiple Egyptian clubs.
Tensiomyography (TMG) Parameters were assessed regarding Contraction time (Tc), Maximal
displacement (Dm), Sustain time (Ts), Relaxion time (Tr) and Delay time (Td) in Rectus femoris (RF),
Vastus medialis (VM) and Vastus lateralis (VL) separately and correlated with functional performance;
number of repetitions in 30 seconds for anteromedial lunge test, balance and reach test and step-down
test. Outcome measures: Functional performance was measured using functional performance tests;
anteromedial lunge test, balance and reach test and step-down test. Results: It was found that VM Tc,
VL Dm, were moderately positively correlated with anteromedial lunge (r = 0.583, 0.404, p<0.05)
respectively. In contrast, RF Tr was negatively correlated with anteromedial lunge (-0.364, p<0.05);VM Ts,Tr,Dm; VL Td were moderately negatively correlated with balance and reach (r = --0.577, -
0.388, 0.655 and -0.385, respectively, p<0.05). In contrast, VL Tc was moderately positively correlated
with step-down (r = 0.424, p = 0.019). Conclusion: All contractile properties of quadriceps muscle are
significantly correlated with functional performance in long distance runners with PFPS. Future studies
should address these properties, using proper rehabilitation strategies, to improve performance of
runners with PFPS.
