Comparative evaluation of core and knee extensor mechanism muscle activation patterns in a stair stepping task in healthy controls and patellofemoral pain patients

Background: Patellofemoral pain [PFP] is a common affliction and complex clinical entity. Deficit in neuromotor control of the core may be a remote contributing factor to the development of PFPS. Comparative evaluation of core and extensor mechanism muscle activation patterns between healthy group and patients involved by patellofemoral pain syndrome [PFPS] in a stair stepping task is the aim of this study

Methods: In this non-randomized interventional study fifteen males with PFPS and fifteen asymptomatic controls participated. Electromyographic [EMG] activity of Vastusmedialisobliquus [VMO], Vastuslateralis [VL], Gluteus medius [GMED], Gluteus Maximus [GMAX], Internal oblique [IO] and Erector spinae [ES] were recorded and EMG onsets were assessed in both stepping up [SU] and down [SD]. The time of foot contact determined by a foot switch

Results: During SU: Onset times of all muscles except, VL and ES in the controls were significantly less than PFPS group [P<0.05]. In PFPS group the temporal sequence of ES, VL and VMO were different from control groups. During SD: Onset times of all muscles except, GMAX and ES in the control group were significantly less than PFP group [P<0.05]. The sequence of muscle activity in both healthy and PFP groups were the same

Conclusion: Our findings are in line with previous researches about the effects of core on function and control of lower extremity. Activation patterns of core and vasti muscles are different between control and PFPS group during stair stepping task. Designing exercises to correct inappropriate timing of core muscles may have a role in management of PFPS and it needs more future researches

test-retest reliability of the onset of core and vasti electromyographic activity while ascending and descending stairs in healthy controls and patellofemoral pain patients

Patellofemoral pain [PFP] is a common affliction and complex clinical entity. It is hypothesized to result from abnormal patellar tracking caused by altered motor control. Deficit in neuromotor control of the core may be a remote contributing factor to the development of PFP. Application of reliable EMG measures would be helpful to handle this theory. Therefore, the purpose of this study was to determine the test-retest reliability of the core and vasti EMG onsets, while ascending/descending stairs. Ten males with PFP and ten healthy controls participated in this study. Vasti and Core EMG onsets during stair stepping were assessed two times a day. Intraclass correlation coefficients [ICCs] and standard errors of measurement [SEMs] were calculated. Ten males with PFP and ten healthy controls participated in this study. Vasti onsets of control cases [ICC 3,1 >/= 0.70] except Quadratus Lumborum [QL] which showed a moderate reliability [ICC for ascending=0.59 and for descending = 0.61]. In controls, Vasti in both tasks showed the highest absolute reliability. During ascending, high reliability [ICC >/= 0.70] in PFP group was demonstrated for all EMG onsets except Gluteus maximus [GMAX] and QL which showed a moderate reliability [ICC = 0.69 and 0.63 respectively]. In this group while descending stairs, all EMG onsets showed high relative reliability [ICC >/= 0.70]. Moderate to high absolute reliability was obtained for onset times while ascending/descending stairs in PFP group. During both ascending/descending, high reliability was found for all EMG reliability. Most EMG onsets during stair ascending/descending had moderate to high