Free weights vs machines: which is best for increasing size and strength? In a recent 2021 review, it was concluded that there was NO SIGNIFICANT DIFFERENCE between them for increasing muscle size (PMID: 34609100)! However, using machines increased strength on machines the most whereas using free weights increased strength on free weights the most. This means that if you’re trying to increase your bench or squat, then it’s best to stick with free weights. If you’re just concerned with putting on