A large number of devices are marketed for musculoskeletal pain and recovery, and the sport and exercise medicine (SEM) clinician is asked about them constantly, usually by an athlete who has seen one endorsed on social media. This page covers the main remaining modalities as a group: transcutaneous electrical nerve stimulation (TENS), interferential therapy, neuromuscular electrical stimulation, pulsed electromagnetic field (PEMF) therapy, shortwave diathermy, whole-body and local vibration, and the compression and cooling devices used for recovery. They differ in mechanism but share a pattern: a plausible physiological rationale, a large low-quality literature, heavy commercial promotion, and modest or uncertain clinical benefit. The useful skill is not memorising each device but being able to place any new one against the same set of questions.
What are the main modalities and their rationale?
Transcutaneous electrical nerve stimulation delivers current through surface electrodes to stimulate sensory nerves, and its rationale rests on the gate control theory of pain, in which activity in large-diameter afferents inhibits nociceptive transmission at the dorsal horn, with a secondary endogenous opioid mechanism proposed at lower frequencies. Interferential therapy uses two medium-frequency currents and is intended to produce an amplitude-modulated lower-frequency effect where they intersect, on the basis that medium-frequency current crosses skin impedance more comfortably; superior deep penetration should not be assumed. Neuromuscular electrical stimulation is a different proposition again, since it stimulates motor rather than sensory nerves to produce muscle contraction, and it has a defensible, condition-specific role in maintaining quadriceps activation after knee surgery or during immobilisation, with recent evidence supporting improved quadriceps recovery after anterior cruciate ligament surgery. This is the one application in this group with a reasonably coherent rationale and supportive evidence.
The device therapies group into four mechanisms: electrical stimulation of nerve or muscle, electromagnetic field exposure, deep tissue heating, and mechanical loading through vibration. Precautions differ by modality.
Pulsed electromagnetic field therapy applies a time-varying magnetic field through a coil without electrodes, with proposed effects on membrane signalling and bone and cartilage metabolism, and it has been studied most in bone healing and knee osteoarthritis. Shortwave diathermy heats deeper tissue by high-frequency electromagnetic energy and shares the rationale of any deep heating agent. Vibration, applied through a platform or a handheld device, loads tissue mechanically and is proposed to influence muscle activation, flexibility and blood flow. Compression devices and cooling systems are used for recovery rather than treatment, and their claimed effects are largely on perceived soreness. Contraindications differ substantially between these modalities and should not be treated as one shared list. An active implanted device requires modality-specific risk assessment, manufacturer guidance and, where appropriate, specialist advice rather than a blanket prohibition. Malignancy in the treatment field, pregnancy, broken or anaesthetic skin and the anterior neck are device-specific precautions or contraindications rather than universal absolute bars, and the applicable list should be taken from the manufacturer and local policy for the specific device.
How should these devices be assessed and discussed?
Taken as a group the evidence is unimpressive. For chronic primary pain, UK guidance states that transcutaneous electrical nerve stimulation, ultrasound and interferential therapy should not be offered because there is no evidence of benefit, and the supporting evidence review found considerable uncertainty with little long-term data. UK osteoarthritis guidance separately advises against neuromuscular electrical stimulation, transcutaneous electrical nerve stimulation, interferential therapy, ultrasound, laser and pulsed shortwave therapy for that condition, which does not negate the postoperative quadriceps indication. Pulsed electromagnetic field therapy has a larger literature in knee osteoarthritis and bone healing with inconsistent results and frequent methodological weakness. Vibration training shows short-term effects on measures such as flexibility and jump performance with little evidence of durable clinical benefit. Compression and cooling devices reduce perceived muscle soreness in some studies, while effects on objective recovery and subsequent performance are inconsistent and usually small. Neuromuscular electrical stimulation is the exception worth defending, with reasonable evidence for maintaining or restoring quadriceps activation where voluntary contraction is limited.
Four questions assess any device: mechanism plausibility, sham-controlled evidence for that specific device and condition, whether the dose is reported reproducibly, and what its use would displace.
The more useful skill is a consistent method for assessing any device, and four questions do most of the work. What is the proposed mechanism, and is it biologically coherent for this tissue at this depth? What does the trial evidence show for this specific device in this specific condition, and was it compared against a credible sham rather than against nothing? What dose was delivered, and is that dose reported in enough detail to be reproduced? And what would be displaced if the patient used it, since the opportunity cost of an ineffective device is the loading programme, the sleep and the load management that would otherwise have occupied that time and attention. Alongside those, the practical considerations are cost, whether the device carries the appropriate current medical-device conformity marking and is being used for its intended purpose, the device-specific precautions above, and, for a competing athlete, that these are physical therapies rather than substances and so are not themselves prohibited, although a device that delivered a substance would be a different question. A low-risk device may reasonably be continued if contraindications have been checked, the person understands the uncertain benefit and the cost, and it displaces neither evidence-based rehabilitation nor recovery priorities. Saying so preserves the credibility needed for the conversations that matter more.
Exam Tips
•Transcutaneous electrical nerve stimulation (TENS) stimulates sensory nerves, with the gate control theory as its rationale and a proposed endogenous opioid mechanism at lower frequencies.
•Neuromuscular electrical stimulation targets motor nerves to produce muscle contraction and has the most defensible, condition-specific role in this group, principally for quadriceps activation after knee surgery, including after anterior cruciate ligament reconstruction.
•Pulsed electromagnetic field (PEMF) therapy applies a time-varying magnetic field through a coil, studied mainly in bone healing and knee osteoarthritis with inconsistent results.
•UK guidance states that transcutaneous electrical nerve stimulation, ultrasound and interferential therapy should not be offered for chronic primary pain, and separately advises against these modalities plus neuromuscular electrical stimulation, laser and pulsed shortwave therapy for osteoarthritis.
•Contraindications are device-specific rather than shared: an active implanted device requires modality-specific risk assessment, manufacturer guidance and specialist advice where appropriate, and malignancy, pregnancy, broken skin and sensory loss are precautions to check per device.
•Assess any new device by mechanism plausibility, sham-controlled evidence for that device and condition, whether the dose is reported reproducibly, and what its use would displace.