Vibrotherapy in rehabilitation after the anterior cruciate ligament reconstruction

Anterior cruciate ligament reconstruction (ACLR) is often associated with chronic quadriceps dysfunction leading to abnormal gait biomechanics and joint damage. Previous studies have shown that vibration improves quadriceps function in people with ACLR, but the duration of these effects is unknown. Therefore, American scientists from High Point University analyzed the time course of quadriceps muscle functional response to whole body vibration (WBV) or local muscle vibration (LMV).

• WBV increased the peak torque of the quadriceps by 5-11% from baseline and relative to the control group at all time points after the intervention.
• LMV increased the peak torque of the quadriceps by 6% from the baseline 10 min after the intervention and by 4-6% compared to the control immediately after and 10 or 20 min after the intervention.

Prepared on the basis of:

Time course of the effects of vibration on quadriceps function in individuals with anterior cruciate ligament reconstruction. Troy Blackburn J, Dewig DR, Johnston CD. J Electromyogr Kinesiol. 2021 Feb;56:102508.

Study population

24 volunteers with primary unilateral ACLR (15 women, 9 men; aged 18-35 years with mean 22 ± 4 years) participated in the study. Participants were required to have a surgeon’s approval to resume unrestricted physical activity.

Test procedure

All volunteers completed 3 training sessions 2-7 days apart: WBV, LMV, or control intervention (no vibration). Before, immediately after, and 10, 20, 30, 45, or 60 minutes after WBV, LMV, or control intervention, isometric peak quadriceps torque, rate of torque development, and EMG amplitude were assessed. Surface EMG of the quadriceps has been used as an indicator of neural activity by which vibration can improve quadriceps function.

During the intervention, participants stood on a Power Plate pro5 (Performance Health Systems, LLC) vibration platform with a slight knee flexion. The platform was only active for the WBV group. WBV was administered in 6 packets of 1 minute duration, with 2 minutes rest in between. The LMV and WBV interventions were identical except that the LMV stimulus was delivered using a prototype device attached to the distal anterior thigh. The same procedures were used in the control group, but without the vibration stimulus. The authors emphasize that although the ideal parameters of the vibration stimulus to facilitate muscle work are unknown, previous work suggests that vibration delivered at a frequency of 30 Hz is optimal for improving the function of the quadriceps.

Use of vibration in the study

WBV or LMV was used at a frequency of 30 Hz and with acceleration of 2 g. Further details are described above (see “Test procedure”).

Results

WBV increased the peak torque of the quadriceps by 5-11% from baseline (p <0.05) and relative to the control group at all time points after the intervention (p <0.05).

LMV increased the peak torque of the quadriceps by 6% from the baseline value 10 min after the intervention (p <0.05) and by 4-6% compared to the control immediately after and 10 and 20 min after the intervention (p <0.05).

The interventions had no effect on the EMG amplitudes or the rate of torque development, but the EMG amplitude of the vastus medialis muscle was greater after WBV compared to the control group directly (p = 0.006) and 20 min (p = 0.009) after the intervention.

Comment

The results of the presented study indicate that a single treatment of vibrotherapy improves the functions of the quadriceps muscle in people with ACLR, in the case of LMV – at least for 20 minutes after the procedure, in the case of WBV – up to 1 hour. This is most likely by increasing the excitability of the CNS. In addition, the sustained for a while response of the quadriceps to a short vibration treatment suggests that vibration can be used in conjunction with standard rehabilitation exercises to improve their effectiveness – vibrations could be delivered before standard exercises.

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