Our friends over at @evidencebasedmvmt did an amazing job at searching the literature to find out whether or not unstable loads alter bar path and muscle activation during the bench press. The belief that bands and unstable loads increase recruitment of stabilizer muscles is under scrutiny.
They found that studies conflict when pointing out exactly which muscles are increasingly activated, or if there is even an increase in EMG activity of smaller stabilizer muscles during this type of training. Ostrowsksi et al found that there is increased activation of the biceps and middle deltoid during unstable benchpress. Lawrence et al found there is increased activation of the rectus abdominis and external oblique during unstable load bar squat. However a study by Dunnick et al found NO difference in muscle activity between unstable and stable training. So, what are some other benefits if any?
In the context of iron sports, training with bands and bamboo bars may be a helpful way to teach athletes to improve body awareness and control in situations involving unstable loads, for example if the bar is misloaded, a plate falls, or you encounter a similar unpredictable event.
They point out that “it is also a fantastic exercise to train specifically for the demands of contact sports, since the athlete is having to control their body in the context of changing and unstable external forces (think of a lineman blocking, or a basketball player scoring through contact). This may lead to a decrease risk of injury!”