Ankle positioning and knee perturbation affect temporal recruitment of the vasti muscles in people with patellofemoral pain

The effect of different hip rotation angles on electromyography activity of the quadriceps muscle during closed kinetic chain tasks in healthy females

[Purpose] The purpose of this study was to investigate electromyographic activity of the quadriceps muscle in different positions of hip rotation (while standing on the toes) in healthy females. [Participants and Methods] The study was conducted on 35 healthy females. Electromyographic activity of the rectus femoris, vastus medialis oblique, and vastus lateralis muscles were recorded with the hip in a neutral position as well as different angles of internal and external rotation (15, 30, and 45 degrees (°)) while the participants were standing on their toes. [Results] There was a significant difference of 15° in external rotation, a neutral position, 15° of internal rotation, and at the end of an internal rotation position. Paired comparison between muscle activity using Bonferroni showed that vastus lateralis activity in 15° of external rotation, a neutral position, 15° of internal rotation, and at the end of a position of internal rotation was more than that of rectus femoris muscle. [Conclusion] The present study showed that average vastus lateralis activity was the highest in all positions. However, the positions studied in the current study did not lead to an increase in muscle activity of the vastus medialis oblique as a medial dynamic stabilizer compared to vastus lateralis.

Delayed onset of vastii muscle activity in response to rapid postural perturbations following eccentric exercise: a mechanism that underpins knee pain after eccentric exercise?

BACKGROUND

Appropriate timing of activity of the vastus medialis obliqus (VMO) and vastus lateralis (VL) muscles is a key factor for proper tracking of the patella in the trochlear groove during knee extension. This study investigates the relative timing of activation of the VMO and VL muscles during unexpected perturbations performed before and after eccentric exercise.

METHODS

Surface electromyography signals were recorded from the VMO and VL muscles of the right leg in 11 healthy men during rapid postural perturbations performed at baseline, immediately after eccentric exercise of the quadriceps, and at 24 and 48 h after exercise. Participants stood on a moveable platform during which eight randomised postural perturbations were performed (4 repetitions of 2 perturbation types: 8 cm forward slides, 8 cm backward slides).

RESULTS

Before the eccentric exercise, the onset of VMO activity was significantly earlier than the VL muscle (average for both forward and backward perturbations: VMO 39.0±7.1 ms; VL 43.7±7.9 ms). However, the onset of VMO activity was significantly later compared with VL muscle immediately after eccentric exercise and this remained 24 and 48 h after eccentric exercise (average across all postexercise sessions and perturbation directions: VMO 72.3±11.1 ms; VL 56.0±8.2 ms; p<0.05).

CONCLUSIONS

The onset of VMO-VL activity in response to rapid destabilising perturbations is altered immediately after eccentric exercise and during eccentric exercise-induced muscle soreness up to 48 h later. These observations may help explain the high prevalence of knee disorders after high intensity eccentric exercise.

The non-operative treatment of anterior knee pain

Anterior knee pain is a common presenting complaint, and in many cases no identifiable cause can be found. In these circumstances it is commonly known as anterior knee pain syndrome or patellofemoral pain syndrome. The management for this condition is most commonly non-operative. Treatment strategies include physiotherapy, pharmacotherapy, orthoses and combinations of the above. There are many described methods in the literature with a wide spectrum of outcomes, which in itself is testimony to the lack of any generally accepted gold standard of care for these patients. It is thus unclear to the health care professional treating these patients which is the best treatment to offer. In this review we aim to summarise historical and most up to date literature on the subject and in so doing allow the health care professional pick whichever treatment strategy they feel most beneficial and also provide a guide for appropriate patient education.

Comparison between an accelerometer and a three-dimensional motion analysis system for the detection of movement

OBJECTIVE

To examine the reliability and concurrent validity of an accelerometer compared with a three-dimensional (3D) motion analysis system for measuring the motor reaction time of the lower limbs, to validate a simple method for objective clinical assessment of movement onset.

DESIGN

Timing of the onset of knee extension movement in response to an audio signal was measured simultaneously with an accelerometer and a 3D VICON motion analysis system.

PARTICIPANTS

Twelve able-bodied subjects with a mean age of 26 (standard deviation 2.3) years.

RESULTS

Good reliability was found for both instruments, although the intraclass correlation coefficient (ICC) was higher for the accelerometer (ICC₃,₁=0.739; P<0.001). The mean motor reaction time measured by the accelerometer and the VICON system was 205.0 and 196.9 mseconds, respectively. Good agreement was found between the paired measurements (mean ICC=0.774), and the average 95% limits of agreement were -56.4 to 72.5 mseconds.

CONCLUSION

In conclusion, the accelerometer had good reliability for the measurement of movement onset time. Agreement between the measurements from the accelerometer and the VICON system was high. However, the limits of agreement covered a wide range, so absolute timings for movement onset derived from these methods should not be used interchangeably.