Electrically Elicited Quadriceps Muscle Torque: A Comparison of 3 Waveforms

The effects of the Aussie current on pain, torque and muscle strength: Systematic review

BACKGROUND

The Aussie Current (AC) is a medium frequency electrical current of 1 and 4 kHz modulated in bursts used to reduce pain, increase muscle strength and produce torque in adults. However, there is still no consensus on these effects.

OBJECTIVES

To systematically review available evidence on the effects of AC on pain, muscle strength, torque, comfort and functionality in adults.

METHODS

This systematic review was conducted according to PRISMA guidelines and registered in PROSPERO. A search was carried out in the Lilacs, Scielo, Web of Science, Scopus, Pubmed and PEDro databases, from 10/2021 to 02/2022. Randomized or non-randomized clinical trials that investigated the effects of the application of AC were selected. Two reviewers independently assessed the risk of bias in the studies using the JADAD scale. The quality of the evidence of some outcomes was assessed using the GRADE system of rating The selected studies used AC as intervention and presented pain, muscle strength, torque, comfort and/or functionality as outcomes.

RESULTS

21 studies (590 participants) were included. 14 articles were classified as low quality and 7 as high quality. The quality of the evidence was moderate. The effects of AC on the studied outcomes are still controversial. As for the consensus regarding the chosen frequency, 80,9% (n = 17) of the studies used the frequency of 1 kHz.

CONCLUSION

Although it was verified that the frequency of 1 kHz is the most used, the studies that address AC are scarce and with methodological diversity, which makes it difficult to assess the effectiveness of this current. Thus, we suggest that further studies should be carried out to elucidate the effects of AC on pain, muscle strength and torque production.

Effect of Russian current expert modes on quadriceps muscle torque in healthy adults: A single-blinded randomized controlled trial

BACKGROUND

Russian current (RC), a well-known neuromuscular electrical stimulation operating at 2500 Hz, has demonstrated significant strength improvement over traditional exercises due to its high tolerance and low pain provocation. Despite extensive NMES parameter research, the specific effects of expert modes, particularly ON2 and Rest, remain unexplored. This study investigates the direct effect of these expert modes on quadriceps muscle strength in healthy adults.

METHODS

This is a single-blind, randomization-controlled trial. Forty-eight healthy university students (31 females, 17 males) were assigned in two randomized experimental groups either the ON2 or Rest mode for a 15-minute electrical stimulation session. Quadriceps maximum voluntary isokinetic contraction measurements were taken before and directly after RC application using Biodex Medical Systems 4 pro isokinetic dynamometer.

RESULTS

Both RC modes significantly increased the quadriceps muscle torque in healthy adults compared to baseline (p<0.05). Baseline mean torque was 123.28 (SD = 38.8), and post- RC mean torque was 136.67 (SD = 45.76). Deviation from normality was observed at baseline (p = 0.034) and persisted post-RC application (p = 0.017). The Wilcoxon test reported significant increases in quadriceps muscle knee torque for both ON2 and Rest groups (p < 0.001). The lack of ties in ranks and negative Z-values highlight the robustness of the observed effects.

CONCLUSION

The findings of this study align with previous research on NMES and RC supporting the idea that electrical stimulation enhances muscle strength, selecting the appropriate RC expert modes can assist physiotherapist in tailoring rehabilitation program to achieve their specific strength goals.

KiloHertz currents on aspects of muscle function: A scoping review

BACKGROUND

Neuromuscular electrical stimulation (NMES) with kiloHertz currents (kHz) is a resource used in rehabilitation for producing muscle contractions with functional objectives, resulting from the optimization of the performance of aspects of muscle function (AOMF). However, parameters such as inadequate frequency, phase duration, amplitude, and therapy time may limit the effectiveness of NMES by the absence of adequate stimuli to generate positive adaptations in the AOMF. This study aimed to present an overview of the effectiveness and dosimetry of NMES by kHz on AOMF, such as torque and hypertrophy, in healthy people.

METHODS

The study was outlined as a scoping review. From the search, 3892 studies were found of which were incorporated into Rayyan software for exclusion of duplicates and further selection by titles and abstracts, which resulted in 33 articles for this review.

RESULTS

According to the included studies, kHz can increase torque and generate hypertrophy. Only the studies with Russian current showed hypertrophy gains. Dosimetry was not always detailed in the studies, which hinders stipulating optimal parameters for kHz.

CONCLUSION

From this review, it is concluded that NMSC by kHz is a valid resource to optimize AOMF, although the dosimetric parameters are still inconsistent.

Recommendations to Increase Neuromuscular Electrical Stimulation Training Intensity During Quadriceps Treatments for Orthopedic Knee Conditions

Neuromuscular electrical stimulation (NMES) is often used by clinicians as a therapeutic adjunct to improve quadriceps strength deficits following orthopedic knee conditions. The efficacy of NMES treatments is primarily dependent on the NMES training intensity, which is a direct result of NMES-induced torque production. The importance of NMES training intensity is well known, yet adequate NMES training intensities are often difficult to achieve due to a variety of limitations associated with NMES (eg, fatigue and patient discomfort). This article provides recommendations that a clinician can use to increase NMES training intensity when strengthening the quadriceps with NMES for orthopedic knee conditions. These recommendations should allow forceful contractions that can be sustained over a treatment with multiple repetitions without the rapid decline in force that is typically seen when NMES is used.