Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily  Front Page newsletter and new  audio briefings. Whether at home, in the factory or in the office, it is the advice invariably issued to anyone preparing to lift a heavy object. “Keep your back straight, bend your knees.” A new study argues that while most people instinctively believe lifting with a straight back is common sense, “round-back lifting” is more efficient and no more hazardous. Published in the Scandinavian Journal of Pain, it points to research conducted on forestry workers which found that those who stooped to pick up their loads… However, a group of scientists has called for a review of health and safety guidelines after claiming the technique is based on scant reliable evidence – and may even be inferior to a bent-back approach.