©by the National Athletic Trainers' Association, Inc. Context: Various modalities have been used to pretreat skeletal muscle to attenuate inflammation. Objective: To determine the effects of short-wave diathermy (SWD) preheating treatment on inflammation and stress markers after eccentric exercise. Design: Controlled laboratory study. Setting: University laboratory setting. Patients or Other Participants: Fifteen male (age = 22 ± 4.9 years, height = 179.75 ± 9.56 cm, mass = 82.22 ± 12.67 kg) college-aged students. Intervention(s): Seven participants were selected randomly to receive 40 minutes of SWD heat treatment (HT), and 8 participants served as the control (CON) group and rested without SWD. Both groups completed 7 sets of 10 repetitions of a high-intensity eccentric exercise protocol (EEP) at 120% of the 1-repetition maximum (1-RM) leg extension. Main Outcome Measure(s): We biopsied muscles on days 1, 3 (24 hours post-EEP), and 4 (48 hours post-EEP) and collected blood samples on days 1, 2 (4 hours post-EEP), 3, and 4. We determined 1-RM on day 2 (24 hours post-SWD) and measured 1-RM on days 3 and 4. We analyzed the muscle samples for interleukin 6 (IL-6), tumor necrosis factor α, and heat shock protein 70 and the blood for serum creatine kinase. Results: We found a group × time interaction for intramuscular IL-6 levels after SWD (F2,26 = 7.13, P = .003). The IL- 6 decreased in HT (F1,6 = 17.8, P = .006), whereas CON showed no change (P > .05). We found a group × time interaction for tumor necrosis factor a levels (F2,26 = 3.71, P =.04), which increased in CON (F2,14 = 7.16, P = .007), but saw no changes for HT (P > .05). No group × time interactions were noted for 1-RM, heat shock protein 70, or creatine kinase (P > .05). Conclusions: The SWD preheating treatment provided a treatment effect for intramuscular inflammatory myokines induced through high-intensity eccentric exercise but did not affect other factors associated with intense exercise and inflammation.