Effect of burst TENS and conventional TENS combined with cryotherapy on pressure pain threshold: randomised, controlled, clinical trial

Abstract

ObjectiveTo assess the immediate effect of conventional and burst transcutaneous electrical nerve stimulation (TENS) in combination with cryotherapy on pain threshold and tolerance in healthy individuals. DesignRandomised, controlled trial. SettingUniversity laboratory. ParticipantsOne hundred and twelve healthy women. InterventionsVolunteers were allocated at random to seven groups (n=16): (1) control, (2) placebo TENS, (3) conventional TENS, (4) burst TENS, (5) cryotherapy, (6) cryotherapy in combination with burst TENS, and (7) cryotherapy in combination with conventional TENS. Pain threshold and tolerance were measured by applying a pressure algometer at the lateral epicondyle of the humerus, before and after each intervention. Main outcome measuresThe primary outcome measure was pressure pain threshold. ResultsA significant increase in pain threshold and tolerance at the 5% level of significance was recorded as follows: burst TENS {pain threshold: mean difference 1.3 [95% confidence interval (CI) 1.4 to 1.2]; pain tolerance: mean difference 3.8 (95% CI 3.9 to 3.7)}, cryotherapy [pain threshold: mean difference 1.3 (95% CI 1.4 to 1.2); pain tolerance: mean difference 1.9 (95% CI 1.8 to 2.0)] and cryotherapy in combination with burst TENS [pain threshold: mean difference 2.6 (95% CI 2.4 to 2.8); pain tolerance: mean difference 4.9 (95% CI 5.0 to 4.8)]. Cryotherapy in combination with burst TENS provided greater analgesia compared with the other groups (P<0.001). ConclusionThese results support the use of cryotherapy in combination with burst TENS to reduce induced pain, and suggest a potentiating effect when these techniques are combined. No such association was found between cryotherapy and conventional TENS.