The traditional deadlift using free weights and a barbell is considered an isotonic (constant external resistance) exercise. Due to the properties of elastic bands, supplementing them with a free weight exercise adds variable resistance. Prior research of variable resistance combining free weights and resistance bands has shown short term power and strength gains in the bench press and back squat (1).
According to Galpin et al (2008), "this variable resistance (i.e., bands) strategy should therefore address the limitations of isotonic exercise by allowing greater loading at body positions of greater mechanical advantage." What this means is that supplementing the deadlift with bands challenges the finish position (hips fully extended) more than the traditional free-weight deadlift without bands. The further the bands stretch, the greater the external resistance!
The study by Galpin et al (2008) looked at the effects of combined elastic bands and free-weight resistance during a conventional deadlift at moderate (60%) and high (85%) intensities.
- Regardless of lifting intensity, the amount of force produced decreased as the total amount of tension from the bands increased
-Velocity increased as the amount of elastic band resistance increased
-Overall power increased as the amount of elastic band resistance increased
The practical application of this study depends on the training session and/or athlete's goal. If you want to maximize power, you should implement heavy bands. If you want to maximize force, you want to use free-weights with little to no elastic bands. One limitation to this study is that these rules may not apply to inexperienced weight lifters as the study subjects had at least six months of experience performing dead lifts with elastic bands. The supplementation of elastic bands increases the amount of technical proficiency needed to perform the lift.
Anderson, CE, Sforza, GA, and Sigg, JA (2008). The effects of combining elastic and free weight resistance on strength and power in athletes. J Strength Cond Res 22: 567–574