Output of Electronic Muscle Stimulators: Physical Therapy and Police Models Compared

Area of Science:

• Biomedical Engineering
• Physiology

Background:

• Electrical muscle stimulation (EMS) is utilized by physical therapists and law enforcement.
• Physical therapy EMS units typically use adhesive patches, while law enforcement models employ needle electrodes.
• Limited research exists on the electrical output characteristics of physical therapy EMS devices.

Purpose of the Study:

• To compare the electrical output of commercially available Transcutaneous Electrical Nerve Stimulation/Electrical Muscle Stimulation (TENS/EMS) units with law enforcement electrical weapons.
• To analyze device performance across different impedance loads.

Main Methods:

• Six TENS/EMS units were purchased and tested.
• Electrical output was measured using loads of 500 Ω, 2 kΩ, and 10 kΩ.

Main Results:

• At a 500 Ω load, EMS units delivered the highest current, followed by electrical weapons, and then TENS units.
• At impedances greater than 2 kΩ, electrical weapons delivered more current than EMS units, attributed to their higher voltage compliance.
• Some multi-channel EMS units provided greater calculated muscle stimulation than multi-channel weapons.

Conclusions:

• Current therapeutic EMS devices can deliver more current than law enforcement muscle stimulators under specific conditions.
• The performance difference is influenced by impedance levels and device circuit design, particularly voltage compliance.