IBS machines have seen a bit of a re-emergence of late, which is odd given the "functional" phenomenon. I wouldn't favor IBS machines to general freeweight training, however, they're a nice alternative to have, particularly if you're performing sport-specific training. For example, the alternating IBS Chest Press shown is a sensible sports-specific exercise choice for say a runner or boxer during a competitive phase of their training.
For workout examples, including sports-specific workouts, check out our free gym workouts database under the 'Workouts' category.
Muscle worked during the IBS Chest Press:
Primary Muscles: Pectoralis Major - Mid Sternal Fibres.
Secondary Muscles: Anterior Deltoids, Triceps, Serratus Anterior, Anconeus.
Stabilizing Muscles: Lateral Deltoids, Rectus Addominis, Transversus Abdominis, Forearm Flexors...