Objective To consider the efficacy of 10 weeks of Romanian deadlift (DL) training in increasing lumbar extension strength compared to isolated lumbar extension (LUMX) training. Design Comparison of pre- and post-test data for Romanian deadlift 1RM, and lumbar extension torque between and within groups. Participants Male trained subjects (n = 36; 24.9 ± 6.5 years; 178.5 ± 5.2 cm; 81.6 ± 10.0 kg). Main outcome measures Pre- and post-testing included a Romanian deadlift 1RM and isometric strength tests every 12° through full range of motion on the MedX lumbar extension machine (MedX, Ocala, FL). Results Repeated measures analysis of variance (ANOVA) with Bonferroni adjustments revealed that 1RM Romanian deadlift significantly increased from pre- to post-test in the DL group (p < 0.008; 143.3 ± 23.4 kg to 166.3 ± 21.9 kg) and the LUMX group (p < 0.008; 135.8 ± 23.1 kg to 146.0 ± 25.5 kg). In contrast, tested functional torque (TFT) significantly increased at 6 out of 7 joint angles (p < 0.008) for the LUMX group only. The control group showed no significant differences pre- to post-test. Conclusions These data suggest that the Romanian deadlift does not enhance lumbar extension torque. However, performing specific isolated lumbar extension training appears to improve both lumbar extension torque and Romanian deadlift 1RM.