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Effectiveness of electrical stimulation on rehabilitation after ligament and meniscal injuries: a systematic review

Imoto, A.M., Peccin, S., Almeida, G.J.M., Saconato, H. and Atallah, Á.N., 2011. Effectiveness of electrical stimulation on rehabilitation after ligament and meniscal injuries: a systematic review. Sao Paulo Medical Journal, 129, pp.414-423.

In today’s letter

• Main thoughts on whether electrical muscle stimulation (EMS) helps regain muscle strength after a sustaining ligament or meniscal injury

• A fun infographic for you to save and use in the future

• Rapid Results =

The evidence from randomised clinical trials, though of limited quality, clearly show that electrical EMS, when combined with a rehab program, is more effective in improving muscle strength and function for up to two months after ACL reconstruction compared to just rehab

• 3 resources to check out to further your knowledge about EMS use

• Meme of the week: Oh yes! Oh noo..

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Aim of the study

To assess the effectiveness of electrical stimulation for rehabilitation after soft tissue injuries of the knee (anterior cruciate, posterior cruciate, lateral and medial ligament and meniscal injuries), treated surgically or conservatively

EMS Promotes Early Strength Recovery

Electrical Muscle Stimulation (EMS) has been shown to work really well in the early stages of rehab following ligament and meniscal injuries, particularly within the first six weeks post-surgery.

During this phase, muscle wasting can occur quickly. After immobilisation due to surgery, the quadriceps muscles are at high risk for significant weakness. In fact, studies have shown that quad strength can decrease by 60-80% after just five to six weeks of immobilisation. This rapid decline in strength makes it very important to focus on early interventions to preserve muscle function and prevent long-term deficits.

This is where EMS enters..

EMS helps by directly stimulating muscle fibers through electrical impulses, mimicking the signals the nervous system would normally send. This process bypasses the brain’s natural activation pathways and stimulates the muscle fibers, even those that may be dormant or weakened due to the injury.

This means that more muscle fibers, including the type I (endurance) and type II (strength) fibers, can be recruited during recovery. Notably, type II fibers are typically the ones most affected by muscle disuse, so EMS gives a way to activate them when they might otherwise remain inactive during the healing phase.

Furthermore, EMS helps reduce muscle atrophy in the early post-surgical period, giving stimulus for recovery when conventional rehab may be too risky or difficult to perform.

As a result, EMS is particularly beneficial in preventing the rapid muscle wasting that often occurs during the immobility and sets a solid foundation for strengthening exercises later in rehab.

Better Results When Combined with Exercise

One of the most compelling findings in this systematic review is that EMS works best when combined with exercise. While exercise is the cornerstone of rehab, combing the two can give significant benefits, especially in the early stages.

As mentioned EMS stimulates the muscles directly, activating muscle fibers more effectively than voluntary contraction during activity. This combined stimulation leads to more significant gains in muscle strength and functional capacity.

The benefit of combining EMS with exercise is mainly due to the activation of muscle fibers. EMS activates both type I endurance fibers and type II fast-twitch fibers.

Traditional rehab typically focus on endurance training and may not activate fast-twitch fibers effectively, particularly during the initial stages of recovery when the patient has certain restriction.

EMS, however, bypasses this limitation, making sure that both fiber types are engaged. This dual activation increases overall muscle strength and functionality more than voluntary exercises alone.

These benefits are seen in several studies with ACL reconstruction patients.

For example, Snyder-Mackler and colleagues observed a 70% recovery of quadriceps strength with high-intensity EMS, compared to 57% with exercise alone.

Ist obvious that EMS adds some serious value, particularly during the early rehabilitation stages, when muscles are weakest and the risk of atrophy is highest.

Clinical tip

Aim to use EMS the first six weeks after surgery.

The ideal low frequency for boosting muscle strength is between 35 to 80 Hz. For medium frequency, use a modulation of 2500 Hz/50-75 Hz. Aim for a pulse duration of 200 to 350 microseconds, and during the early rehabilitation phase, maintain a contraction-to-rest ratio of about 1:5 for the most effective results

Top 3 Resources to Check Out

And learn more about EMS

1. Exercise Protocol and Electrical Muscle Stimulation for patellar tendinopathy (Study) - Link

2. How to use EMS

3. How does it work?

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