Forced Reps vs. Regular reps

October 20th, 2007 by Paul Johnson

The high intensity workout routine advocates such as HIT, often use forced reps as a way to increase the intensity of a set. Forced reps are when you do a few reps in a set beyond muscular failure. When you can no longer do the positive (concentric) motion of the rep, you have hit muscular failure. In order to continue with the set, you have a workout partner help lift the weight on the positive portion, for an additional 2 or 3 more reps, called forced reps. Is there really any benefit to doing forced reps? Let’s see what some studies have found.

Forced rep studies:

A study was published in Int J Sports Med. 2003 Aug;24(6):410-8. done on 16 athletes comparing forced reps to traditional reps. The traditional reps were 4 sets of leg presses, 2 sets of squats and 2 sets of knee extensions (with 12 repetitions) with a 2-min recovery between the sets and 4 min between the exercises. For the forced sets they chose a weight higher so they had to have assistance to complete 12 reps(to failure). Both types of rep sets led to large spikes in in serum testosterone, free testosterone, cortisol and GH concentrations. However the forced reps had larger increases in GH and cortisol. The more obvious part of the study results, was that it had more of an impact on strength (neuromuscular function).

Another study (Can J Appl Physiol. 2004 Oct;29(5):527-43) was also done comparing forced repetitions to regular. One group was 8 strength trained individuals with years of experience, while the other group was active, but not in strength training. The traditional rep group did squats for 4 sets with a 2-min recovery between sets for 12 reps to failure. The forced rep group did a higher weight, so they could complete 8, and an additional 4 with assistance. Both groups had a spike in serum testosterone, free testosterone, cortisol and growth hormone concentrations, with the trained athletes having a larger response. All the hormonal responses were greater in the forced rep sets than in the normal sets. The study also found a greater neurmuscular adaption. Researchers concludedthat the forced rep for experienced athletes, can be a good alternative, and may even be better than traditional sets.

Although forced reps seem to induce more stress on the CNS and hormones, whether or not that actually leads to "real world" better strength and muscle gains, is unclear from current research. Regardless, forced rep training should be looked at as a temporary workout parameter, due to the potential for injury and overtraining. Long term overuse of it, would release a lot of cortisol and overstress the CNS, leading to overtraining. The cons would outweigh the benefits in the long run, as you would be causing more stress to the body than is necessary for optimal muscle stimulation. Forced reps can be a good way however, to help shock your muscles into new growth, if you are currently on a plateau. Eventually your muscles will adapt to forced rep training and you will plateau again, just like with any training routine.

For additional reading:

Training to muscle failure