1. Alternating Frequencies of Transcutaneous Electric Nerve Stimulation: Does it Produce Greater Analgesic Effects on Mechanical and Thermal Pain Thresholds? 
K.C. Tong, MSc, Sing Kai Lo, PhD, Gladys L. Cheing, PhD 
Archives of Physical Medicine and Rehabilitation 
Volume 88, Issue 10, Pages (October 2007)
DOI: /j.apmr
Copyright © 2007 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

2. Fig 1
Placement of TENS electrodes recording sites for the MPT and HPT.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2007 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

3. Fig 2
HPT and MPT were recorded at various time intervals; baseline measurements were recorded at t1 and t2; t3 and t4 were time periods when intervention took place; postintervention measurements were recorded at t5 and t6.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2007 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

4. Fig 3 Percentage change in HPT, compared with baseline.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2007 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

5. Fig 4 Percentage change in MPT, compared with baseline.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2007 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions