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Background and Aim: This study was performed to compare the stiffness of hamstring and rectus femoris muscles in subjects with anterior knee pain and normal subjects.

Materials and Methods: In this non experimental and case-control study, 20 persons with anterior knee pain were selected simply from convenient sample and 20 healthy persons were selected by matching method. proximal and distal stiffness of hamstring and rectus femoris muscles were measured using an isokinetic device in the passive mode. Also, maximal concentric peak torque during flexion and extension movements of hip and knee, in two groups were compared by independent T-test and correlation analysis.

Results: There was no significant difference between anterior knee pain and proximal compartment of rectus femoris(P=0.320) and hamstring(P=0.125) stiffness, but there was significant difference between anterior knee pain and distal compartment of rectus femoris and hamstring stiffness (P<0.001). Significant relationship was found between anterior knee pain and muscles strength (P<0.001). No correlation was found between strength and stiffness of rectus femoris (P=0.356) and hamstring muscles (P=0.643) in patients group, but in healthy subjects this relationship was found (P<0.001). 

Conclusion: In patients with anterior knee pain, hamstring and rectus femoris muscles stiffness increased and muscle strength decreased. Increasing of muscle strength was effective on stiffness in healthy subjects, but there was no relation between them in patients group. Also rectus femoris and hamstring muscles possibly have different proximal and distal neuromuscular compartments.

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Background and Aim : The aim of this study was to determine the effects of fatigue due to plyometric training on vertical jump ability and activity pattern of rectus femoris of dominant leg of high jump of active girls .

 

Materials and Methods : Seventeen females , mean age (21.5 ± 0.76 years ) were randomly assigned to two experimental (n = 10 ) and control ( n = 7) groups. Experimental group performed plyometric training and control group had no activity. Before and after training , vertical jump test using Ergo jump and electrical activity of rectus femoris muscle of dominant leg using electromyography were tested . The results of vertical jump test showed a decrease in performance (p: 0.04, F: 4.5) and fatigue process was confirmed . The raw EMG signal based on deep jump phases was divided in three phases and only 2 phases of the first were analyzed . In every phase, the maximum activity , amplitude and total time were obtained .respectively. M ultivariate analysis of variance (2×2) was used to compare of post-test of two groups.

 

Results : After one session training , rectus femoris maximum activity of the experimental group showed a significant decrease in pre-activation phase of motor program .

 

Conclusion : This study showed that neural fatigue due to plyometric training can occur in motor program (especially in pre-activation phase of motor program ).

  

Keywords : Deep jump, Plyometric training, Vertical jump, Electromyography, Rectus femoris muscle.