CRICKETERS who are proud of their fast bowling technique may be putting themselves at risk of serious back injury, says a report in the British Journal of Sports Medicine. It points out that 38 per cent of a group of 82 young Western Australian fast bowlers sustained significant back injuries and 11 per cent developed fractures. Factors that put stress on the back include poor 'mixed action' technique, bowling too fast and too long, and bowling too many overs in a spell.