Aim Patellar tendon (PT) strap is commonly used for jumper’s knee to alleviate pain during jumping activities in sports.1 But it is still unclear whether PT strap can affect the jumping performance or not. This study is intended to clarify the PT strap effects on maximal jump height and EMG onset timing difference during squat jump.
Materials/methods 5 male athlete participants attended to the study. 3 squat jumps were performed with and without PT strap and the highest jump trial was chosen for analysis. Squat jump was studied as jumping and falling activity. EMG electrodes were placed over the area of greatest muscle bulk of vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) muscles of right knee in order to collect EMG data. 5 reflective markers were attached to heel, toe, ankle, knee and hip to determine the start and finish of the movement and to analyse the kinematics of the movement. Maximal and basal EMG data and also EMG data during jump activity were collected with pre-amplified, single differential EMG electrodes at 1000 Hz. (DE-2.1, DelsysInc., Boston, MA). Maximal voluntary isometric contraction EMG data was used for normalisation of the EMG activity.The jumping performance were captured at 500 Hz. (PhotronSA3 Camera, Japan). EMG data were preamplified (1*) distal to the surface electrodes, band-pass filtered between 20 and 250 Hz, full wave rectified and low pass-filtered at 50 Hz (sixth-order Butterworth filter). The image datas were also low pass-filtered at 50 Hz (sixth-order Butterworth filter). Peak EMG value, EMG onset timing difference and maximal jump height calculations were compared. Independent samples t-test was applied for two conditions (with strap and without strap).
Results There were no significant differences between maximal jump heights of the participants’ w/wo strap (44.39 ± 6.26, 44.53 ± 5.31 in order). Peak EMG activity was similar for two conditions during jump and fall activity (Figure 1). Patellar tendon strap did not show a significant delay on the onset of the quadriceps muscles (Figure 2).
Discussion Earl et al.2 reported a significant decreased quadriceps EMG activity during lateral step down exercise when using a knee brace. However, in our study there was no statistical alteration for quadriceps muscle EMGs during squat jump also for jump and fall phase.Also strapping improved VM-VL onset timing difference, during squat activity but not significantly.Strapping and taping decreases patellofemoral pain by altering VM-VL EMG delay in symptomatic patients.3 The squat jump activity needs high motor unit recruitment and elicits higher normalised peak EMG activity when compared with lateral step down. The higher EMG need for quadriceps muscle during squat jump may hinder the suppression of the brace for quadriceps EMG peak activity. Also in healthy subjects, there may be no delay between VM-VL EMG activity and no symptoms and due to that, there may be no significant improvement for onset timing difference during strapping condition.
Conclusion According to this preliminary study, PT strap did not affect jump height and EMG activity during jump and fall activities.
deVries A, Zwerver j, Diercks R, et al. Effect of patellar strap and sports tape on pain in patellar tendinopathy: A randomised control trial. Scand J Med Sci Sports 2015 Sep 17. doi: 10.1111/sms.12556.
Earl JE, Piazza SJ, Hertel J. The Protonics Knee Brace Unloads the Quadriceps Muscle in Healthy Subjects. J Athl Train 2004;39:44–49
Mostamand J, Bader DL, Hudson Z. The effect of patellar taping on EMG activity of vasti muscles during squatting in individuals with patellofemoral syndrome. J Sports Sci 2011;29:197–205.
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