Resistance bands - e.g. these - are always an interesting option for training, especially if the aim is muscle fatigue rather than grunting up the weights.
Here is a study I spotted about the use of bands:
A Comparison of Elastic Tubing and Isotonic Resistance Exercises
The aim of this study was to assess effects of a short-term resistance program on strength in fit young women using weight machines/free weights or elastic tubing. 42 physically fit women (21.79±0.7 years) were randomly assigned to the following groups: (i) the Thera-Band® Exercise Station Group (TBG); (ii) the weight machines/free weights group (MFWG); or (iii) the control group (CG). Each experimental group performed the same periodised training program that lasted for 8 weeks, with 2-4 sessions per week and 3-4 sets of 8-15 submaximal reps. A load cell (Isocontrol; ATEmicro, Madrid, Spain) was used to test the evolution of the Maximum Isometric Voluntary Contraction (MIVC) in 3 different exercises: Vertical Rowing (VR), Squat (S) and Back Extension (BE). A mixed model MANOVA [group (CG, TBG, MFWG) x testing time (pre-test, post-test)] was applied to determine the effect of the different resistance training devices on strength. The only groups to improve their MIVC (p<0.005) were TBG and MFWG, respectively: VR 19.87% and 19.76%; S 14.07 and 28.88; BE 14.41% and 14.00%. These results indicate that resistance training using elastic tubing or weight machines/free weights have equivalent improvements in isometric force in short-term programs applied in fit young women.
These results indicate that resistance training using elastic tubing or weight machines/free weights have equivalent improvements in isometric force in short-term programs applied in fit young women.
So, bands worked just as well in this experiment