Visuomotor reaction time difference between patellofemoral pain syndrome and healthy individuals: Cross-sectional study.

OBJECTIVE: Although many studies indicated a decreased reaction time in post-traumatic complaints including ACL injury, no study has been devoted to measure reaction time in patients with patellofemoral pain syndrome (PFPS). The purpose of the present study was to compare the visuomotor reaction time between PFPS and healthy individuals. METHODS: Twenty five patients with PFPS (20 women and 5 men, mean age 29.28 years, SD 5.59) and 25 healthy controls (19 women, 6 men, mean age 29.32, years SD 5.30) were recruited in the present study. The dependent variables were upper extremity reaction time, upper extremity error rate, knee extension reaction time in both involved and non-involved legs, plantar flexion reaction time in both involved and non-involved legs. RESULTS: The results of one-way multiple analysis of variance showed that patients with PFPS had slower upper extremity reaction time (P=0.047, Effect size (ES)=0.39) and plantar flexion reaction time (symptomatic side) (P<0.001, ES=0.77) as compared with healthy control. The symptomatic knee extension reaction time was slower than the healthy matched leg, but this difference was not statistically significant (P=0.296, ES= 0.19). CONCLUSION: The present study suggests that the reaction time might be considered as a factor associated with PFPS.

Reliability of postural control during double-leg standing in subjects with nonspecific chronic low back pain: Dual-task paradigm and manipulated visual and somatosensory inputs.

BACKGROUND: The aim of this study is to evaluate the test-retest reliability of the Center of Pressure (COP) parameters in quiet double-leg standing in subjects with Non-Specific Chronic Low Back Pain (NSCLBP) during dual taking associated with manipulated visual and somatosensory inputs. MATERIALS AND METHODS: In this observational cross-sectional study, the static balance of thirty NSCLBP patients were assessed during a double-leg stance by using the force platform. Subjects were accosted by manipulated somatosensory and visual inputs during dual taking in eight different conditions (with and without vibration, eyes-open and eyes-closed, and with and without auditory Stroop test). The COP parameters were recorded as follows: range sideways and range fore-aft as well as mean velocity and area variables. The cognitive task parameters included the reaction time and error ratio. The intra-class correlation coefficient (ICC) was computed to assess the intersession reliability of COP parameters. RESULTS: in intersession, range sideways, range fore-aft, and mean velocity measures possessed moderate to high ICC, but area owned high ICC only in one condition (double-leg stance, eyes-close, with vibration, and with auditory Stroop test). Notably, other conditions had low ICC, and moderate to high and low to very high ICC were reported for reaction time and error ratio. CONCLUSION: Among the parameters studied in the present study, the mean velocity measure seems to be the most reliable variable of postural control in the subjects with NSLBP especially in more challenging conditions, i.e., quiet double-leg standing with eyes closed and adding vibratory inputs during dual-tasking.