If you have ever been to physical therapy, had personal training, or even just looked up how to start a weight lifting program online, there is one thing in common, the number ten.  Most recommendations that professionals give when performing any kind of resistance training, especially for novices or for rehab, is “3 sets of 10”…but have you ever wondered why?

Well, it all started back in 1940’s when Dr. Thomas DeLorme proposed a progressive loading program while he rehabilitated soldiers after World War II.  Being into weightlifting himself, he went against the recommendations of the time to avoid weight lifting, believing that it could have beneficial effects in rehabilitation. 

His first “patient” was Sgt. Thaddeus Kawalek, an older veteran struggling with a knee injury. Dr. DeLorme developed a progressive loading program based on three sets of ten repetitions. His program is set for the subject to perform the first set at 50% of the ten rep maximum, then 75%, and finally 100% of the ten repetition max. This indicates that the weights would be increased with every set.  The results exceeded expectations and Sgt. Kawalek recovered from his knee injury much faster than patients with similar conditions.  Because of this, DeLorme’s method has become the fundamental principle of all resistance training programs.  Of note is the 10 repetition maximum, indicating that the person will struggle to complete all ten repetitions.

There is an opposite theory, called the Oxford Principle, where the persons first set is the ten repetition max, the second is reduced to 75%, and the final set is 50%.  Is there a difference in the training methods? According to Fish, et al in 2003 and DaSilva, et al in 2010, no.  Each method resulted in comparable muscle gains with a low risk of injury, the low risk of injury being the key component in why these methods have also been adapted for use in physical therapy.

So there you have it. The reason so many programs use three sets of ten is because of Dr. Thomas DeLorme.


Todd, Janice S, et al. “Thomas L. DeLorme and the Science of Progressive Resistance Exercise”. Journal of Strength and Conditioning Research. 2012 (11): 2913–2923

Fish, D, et al. “Optimal resistance training: comparison of DeLorme with Oxford techniques” Am Journal of Phys Rehabilitation. 2003; 82: 903-909

Da Silva, et al. “Comparison of DeLorme with Oxford Resistance training techniques: Effects of training of muscle damage markers.” Biology Sport 2010; 27:77-81.


Written by Dr. Travis Stoner PT, DPT, OCS, COMPT, FAAOMPT

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