In the ongoing debate about which is better, free weights or machines, a new 8-week study credits both modalities with producing similar gains in muscle mass and strength among young-adult male and female subjects. One difference, however, was that training with free weights led to greater increases in free testosterone in men.

Some training experts theorize that a higher hormone response may lead to greater muscle hypertrophy and strength over time. While the higher hormone response did occur among male subjects, it did not lead to any differences in training results during the 8-week study time frame.

The study was published in The Journal of Strength and Conditioning Research (2020; 34 [7], 1851–59).