I had a female sprinter I coached in high school who had an injury so that she couldnt run but could lift weights. This is during Indoor Season. She worked hard in the weightroom. Made huge improvements in upperbody strength. Some improvement in lower body. Got her back so that she could start training in Early March. Had a meet one week later. She ran a PR in that race for the 100 and 200. Weights was definitly the difference. She was a junior at the time.