Hamstrings and Quadriceps Muscles Function in Subjects with Prior ACL Reconstruction Surgery

The effectiveness of vibration therapy for muscle peak torque and postural control in individuals with anterior cruciate ligament reconstruction: a systematic review and meta-analysis of clinical trials

Objective

This study aimed to review and summarize the existing evidence on the effectiveness of vibration therapy (VT) in comparison with conventional rehabilitation in anterior cruciate ligament (ACL)-reconstructed patients considering muscle peak torque and postural control.

Methods

We searched available online databases for relevant studies published up to February 2020. All randomized clinical trials investigating the effect of VT on quadriceps peak torque, hamstring peak torque, and postural control (closed-eye and open-eye) were included. Overall, 13 clinical trials with a total sample size of 407 participants were included for the meta-analysis. We used the pooled mean difference with random effects model for meta-analyses. We assessed the heterogeneity of the studies using the I² and Cochran’s Q test. Meta-regression analysis was used to assess the source of heterogeneity.

Results

We found that VT significantly improved hamstring peak torque [weighted mean difference (WMD) 12.67, 95% CI 4.51–20.83] and quadriceps peak torque (WMD 0.11, 95% CI −0.06 to 0.29). However, subgroup analysis showed a significant increase in mentioned muscles’ peak torque in studies employing interventions including both local muscle vibration (LMV) and vibration frequency higher than 100 Hz (WMD 20.84, 95% CI 11.75–29.93). With regard to postural control, we observed a significant improvement only in open-eye mediolateral postural control (WMD 0.26, 95% CI −1.26 to 1.77).

Conclusion

This study suggests that VT, especially LMV type with vibration frequency higher than 100 Hz, can be effective in rehabilitation of ACL-reconstructed patients. Although improvement in the peak torque of hamstring and quadriceps muscles was seen, there was no significant improvement in postural control, especially closed-eye, in comparison with conventional rehabilitation.

Level of evidence

1.

Highlights

Vibration therapy can increase hamstring peak torque in individuals with ACL reconstruction.

Local muscle vibration type in comparison with whole-body vibration is recommended for ACL-reconstructed patients.

Vibration frequency higher than 100 Hz is preferred in ACL-reconstructed rehabilitation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10195-021-00589-5.

Bilateral NIRS measurements of muscle mitochondrial capacity: Feasibility and repeatability

Background

Non‐invasive determination of mitochondrial capacity via near infrared spectroscopy (NIRS) typically involves voluntary exercise of a single muscle group followed by as many as 26 brief ischemic cuff occlusions to determine a single recovery rate constant (k).

Purpose

To determine the within‐ and between‐visit repeatability of a shortened bilateral NIRS protocol, and to establish the feasibility of hamstring k measurements.

Methods

Sixteen young (eight women, eight men; 22 ± 3 years) active adults underwent a bilateral electrical stimulation protocol in which multiple (n = 4) measurements of k for the vastus lateralis (VL) and medial hamstring (MH) muscles were determined on two visits. Repeatability (CV% and intraclass correlations, ICC) and equivalency across visits were assessed for both muscles.

Results

Mean k values in the VL were consistent with published values and within‐visit ICCs were moderately high for both muscles in both sexes. In men, average k values on visit 2 were within 1% (VL muscle) and 5% (MH muscle) of the values on visit 1 (all p > 0.78). In women, average k values were 10%–15% lower on visit 2 (p = 0.01 and p = 0.15 for MH and VL) with the largest between‐visit differences in a subset of participants with the most days between visits.

Conclusions

This bilateral NIRS protocol is time efficient and provides valid estimates of k in both sexes and muscle groups with acceptable within‐visit repeatability. Lower than expected between‐visit repeatability in some participants reinforces the need for further investigation of this newly developed protocol to identify and control for experimental and behavioral sources of variation.

Endurance of the Dorsal and Ventral Muscles in the Neck

Endurance of the muscles of the neck are rarely studied. This study measured the endurance index (EI) of the sternocleidomastoid (SCM) and upper trapezius muscles of the neck (trap). The vastus lateralis (VL) was used for comparison. Skeletal muscle endurance of twelve healthy subjects, age 19-22 years, were tested on their SCM and trap in random order on one day, VL was tested on a separate day. Participants were tested in the supine position for the SCM and VL muscles and the prone position for the trap. Muscle contractions consisted of a 5 Hz twitch electrical stimulation for 5 min. Muscle acceleration (resultant vector) was measured using a triaxial accelerometer. EI was the ending acceleration as a percentage of the maximal acceleration. The endurance index (EI) for the SCM, trap, and VL was 42.3 ± 13.0%, 42.3 ± 20.2%, and 92.9 ± 11.0%, respectively. The EI of the VL was significantly higher than the EI of the SCM (t(2,22) = 10.33, p < 0.001) and the trap (t(2,22) = 7.625, p < 0.001). The EI was not different between the SCM and the trap muscle (t(2,22) = 0.004, p = 0.997). In conclusion, the neck muscles had much less endurance than the muscles in the leg and could make fatigued athletes more susceptible to concussions caused by head impacts.