Hi Emily,
The ADA website has an Into to ADA section that gives some simple info that seems helpful: https://www.ada.gov/topics/intro-to-ada/
I did a quick search on e-stim and came up with these resources:
https://apcp.csp.org.uk/content/guide-use-electrical-stimulation-paediatric-neurodisability
Transcutaneous Electrical Nerve Stimulation (TENS) units are intended for temporary pain relief in sore and aching muscles or symptomatic relief of chronic or acute pain. TENS devices work by sending a string of electrical pulses across the body’s skin and nerve strands. These units have also shown efficacy in releasing endorphins to aid in pain relief.
Neuromuscular Electrical Stimulation (NMES) machines are intended for relaxing muscle spasms, preventing muscle atrophy, increasing blood circulation, maintaining or increasing range of motion, and reeducating the neuromuscular system. The best NMES units aid in physical therapy by being used to strengthen and retrain muscle functions after a surgery or lack of use.
Functional Electrical Stimulation (FES) units offer similar benefits to NMES. When comparing NMES vs FES, FES therapy specifically aids in neurological rehabilitation as the stimulation is automatically controlled to turn muscle contractions into functional movements.
Waveforms:
Medium Frequency: Interferential current and/or premodulation – used to address pain
Asymmetrical Biphasic: TENS/NMES – used for stimulation of the nerve fibers and muscles
Symmetrical Waveform: used for muscle strengthening
Monophasic Waveform: High-voltage pulsed current and microcurrent – used to increase circulation in the tissue