A preliminary examination of cryotherapy and secondary injury in skeletal muscle

Purpose: The purpose of this study was to document the presence of secondar y injury in skeletal muscle, to quantify it, and to determine whether it is altered by acute cryotherapy. Methods: Crush injuries to the biceps surae of 19 adult male Sprague-Dawley rats were either treated continuously with ice for 5 h (N = 10) or received no ice treatment (N = 9). After treatment, tissues were assayed for the reduction of triphenyltetrazolium chloride (T TC) to triphenylformazan (formazan red). TTC reduction is indicative of oxi dative function and serves as an indicator of cellular damage. Results: A s ignificantly lower TTC reduction rare was seen in both cold-treated injured tissue (6.59 +/- 1.01 mu g .mg(-1) . h(-1)) and nontreated injured tissue (4.48 +/- 0.79 mu g . mg(-1) . h(-1)) compared with uninjured controls lice group = 7.94 +/- 1.49 mu g . mg(-1) . h(-1), no-ice group = 6.62 +/- 0.75 mu g . mg(-1) . h(-1)). These data indicate that crushing of muscle tissue produces injury measurable with the TTC reduction assay. Additionally, in c rush-injured tissues, a significantly lower TTC reduction rate was seen in untreated tissues (4.48 +/- 0.79 mu g . mg(-1) . h(-1)) compared with ice t reated tissues (6.59 +/- 1.01 mu g . mg(-1) . h(-1)), indicating that cryot herapy reduces the magnitude of secondary injury. Conclusions: From these d ata, it can be concluded that secondary injury occurs after primary crush i njury and that secondary injury is retarded by acute treatment with 5 h of continuous cryotherapy.