Differing Effects of Nociception and Pain Memory on Isometric Muscle Strength in Participants With and Without a History of Injury: A Quasi-Experimental Study.

Abstract

The goals of this study are to establish whether mechanical pressure pain, short-term memory recall of a painful stimulus, or long-term memory of a previous painful lower limb injury alters isometric muscle strength and whether there was a difference in responses between participants with and without a previous history of injury. Fifty-nine pain-free participants (29 with previous injury and 30 without) participated in this study. Tibialis anterior isometric muscle strength was compared pre- and post-noxious mechanical stimulus with instructions to recall pain (short- and long-term). Short- and long-term pain recall produced a significant reduction in muscle strength (short-term: F (1,57) = 160.472, P < 0.001; long-term: F (1,57) = 128.899, P < 0.001). A greater decrease was experienced with short- and long-term pain memory than exposure to mechanical pain (mechanical pain: -14.8% or -32.98 kg, 95% confidence interval [CI], -41.57 to -24.19; short-term: -24.1% or -52.70 kg, 95% CI = -60.98 to -44.34; long-term: -20.3% or -44.63 kg, 95% CI = -52.77 to -36.95). There was no significant difference in responses associated with an injury history. Findings suggest that recalled pain memory can impact motor responses and calls attention to the role of past injury history in the rehabilitation process.