Did you know that lifting with your legs, not your back does little, if anything to reduce the likelihood of back injury?
In fact, evidence shows that manual handling training focused on how to lift safely provides no long-term benefits on the reduction of lower-back injury.
Rather than providing the same old manual handling training for your workforce, it's far better to assess the work process and identify methods to eliminate heavy lifting. Failing that, a participatory ergonomics assessment conducted with the people who are doing the lifting will also help reduce risk.
If you need help, let me know.