Proper use of SMR has beneficial effects on mobility through two theoretical modes of action:
1) Mechanically allowing lengthening of fascial sheaths and muscle fibres through breaking down localised adhesions and contractures
2) Neurologically resetting the length-tension relationships of muscles and reducing the activation of the muscle stretch reflex.
SMR is not well understood by most gym goers but is beneficial if used regularly before and after workouts, or at any time of the day. It can be very useful specifically for postural correction, a common issue with modern office workers and students who spend their days hunched over a desk for hours.
There are a number of different foam rollers and trigger point balls available on the market at present. I would recommend starting with a less dense/firm roller and progressing to something more firm as your body adapts.
The roller pictured below appears intimidating but it is the highest density roller I have found, and I have worked up from softer ones to using this effectively!
SMR has been an instrumental tool in my scoliosis rehab and sporting endeavours, and helped me immensely in correction of muscular imbalances through regular daily use.