30 minute TENS treatment where the stimulation ramps slowly to zero after 45 seconds. The lights/display on the unit are identical to the Active unit.

30 minute TENS treatment at 100 Hertz (HZ). Intensity set at a strong but comfortable setting and subject asked to increase intensity as tolerated every 5 minutes. Final stimulation intensity at end of Day 1 treatment used for the remainder of the treatment sessions for all 5 days.

30 minute TENS treatment with a pre programed mode alternating from 4 Hz and 100 HZ. Intensity set at a strong but comfortable setting and subject asked to increase intensity as tolerated every 5 minutes. Final stimulation intensity at end of Day 1 treatment used for the remainder of the treatment sessions for all 5 days.

30 minute TENS treatment at a pre programmed mode that ramps between 4 and 125 HZ over 12 seconds. Intensity set at a strong but comfortable setting and subject asked to increase intensity as tolerated every 5 minutes. Final stimulation intensity at end of Day 1 treatment used for the remainder of the treatment sessions for all 5 days.

Transcutaneous electrical nerve stimulation (TENS) is utilized clinically by a variety of health care professionals for the reduction of pain. The mechanisms by which TENS produces analgesia or reduces pain are only recently being elucidated. TENS is a non-invasive modality that is inexpensive, safe and easy to use with relatively few contraindications. Frequency of stimulation is broadly classified as high frequency (>50Hz), low frequency (<10Hz) TENS. Intensity is determined by the response of the patient as either sensory level (low-intensity) TENS strong but comfortable. With sensory level TENS, the voltage (i.e. amplitude) is increased only until the patient feels a comfortable tingling (perceived with high frequency) or tapping (perceived with low frequency) sensation without motor contraction. With strong but comfortable TENS the intensity is increased to a strong but comfortable level which may include muscle contraction.

Pressure pain thresholds (PPTs) change score measured in kilopascal (kPa) will be assessed on the forearm using a pressure algometer. The pressure algometer is mechanical pressure applied by the research assistant at a gradual rate by pushing the device against the skin. The device has a 1 cm2 pad that is in contact with the skin. The subject has a button that they push when the pressure first becomes painful (threshold)which stops the test and the pressure amount is recorded by the research assistant. This is the amount of pressured in kPa that is required to cause a subjective pain of 1/10 on a scale of 0 (no Pain) to 10 (Maximum Pain) rating by the subject. The change score from day 1 to Day 5 is the primary outcome measure.