Limited research exists on the comparison of pulsed shortwave diathermy (PSWD) and instrument assisted soft tissue mobilization (IASTM). In addition, minimal research exists on the AcuForce® 7.0 and none of it examines the effects of the AcuForce® 7.0 on range of motion (ROM). This study focused on the comparison of PSWD and IASTM on hamstring flexibility and perceived patient comfort. Twenty male students, faculty, and staff (age 24.5 ± 5.7 years) participated. Active knee extension ROM with the hip flexed at 90º was measured before and after the intervention. Perceived patient comfort was measured after the intervention. The results showed significant increases in ROM in all subjects (p = 0.013). However, there were no significant differences between groups (p = 0.079). Also, there were no significant differences in perceived patient comfort. The results of this study support hamstring flexibility can be increased with the use of either PSWD or the AcuForce® 7.0.