Q: Some of the really experienced lifters at my gym do a lot of forced repetitions. In talking to these experienced lifters, they think that forced repetitions really maximize their increases in strength. I have been weight training for about a year and have tried using forced repetitions. I noticed that with forced repetitions, I really did not experience a great increase in maximal strength. Should or should I not use forced repetitions?
Forced repetitions or having someone help you complete several more repetitions after you have reached failure at the end of a set is a technique that is frequently used among lifters. Unfortunately, there is relatively little sports science information concerning whether or not forced repetitions after a set is carried to failure are beneficial for increasing either maximal strength or maximal muscle size gains.
One study did report that forced repetitions at the end of sets to failure did result in greater cortisol and growth hormone responses compared to sets just carried to failure. This could be interpreted as a positive response that could result in greater muscle size gains over long-term training. However, this was an acute study, meaning the researchers looked at the response after a training session and did not actually measure changes in strength or muscle size over long-term training. It is quite possible that these greater hormone responses due to the performance of forced repetitions would disappear, or at least decrease in magnitude if forced-repetition training was performed long-term on a regular basis.
Another study looked at the use of forced repetitions when training with the bench press. Basketball and volleyball players trained with forced repetitions for six weeks with three sessions per week. These athletes were familiar with weight training, but probably would be classified as moderately weight trained and not highly weight trained. Results indicated that performing either 1, 3 or 4 forced repetitions per training session did result in increases in maximal strength, but there was no difference in how much maximal strength increased. Maximal strength was measured as changes in both 6- and 3-repetition maximums. Additionally, power during the bench press was also determined and although all groups increased in power, no difference between groups was shown. One aspect of this study that somewhat clouds conclusions is that the group that performed 3 forced repetitions per training session trained using 12 sets of 3 repetitions. The group that performed 4 forced repetitions per training session trained using 4 sets of 6 repetitions and the group that performed 1 forced repetition training session trained using 8 sets of 3 repetitions. This means that total training volume and intensity were different between the different groups. Nonetheless, the results tentatively indicate that there is no difference between performing 1, 3 or 4 forced repetitions per training session of an exercise.
In the real world, some people perform more than 1 to 4 forced repetitions of an exercise per training session. So unfortunately, the bottom line right now is from a sports science perspective very little is known about the benefits or negative aspects, if any, of performing forced repetitions. Some tentative conclusions are that at least when initially performing forced repetitions, there is a different hormone response compared to carrying sets to failure. Whether or not these differences in hormonal response continue during long-term use of forced repetitions or result in increased muscle size and strength gains over long-term training is not known. In moderately weight-trained individuals, using 1, 3 or 4 forced repetitions per training session does result in increased maximal strength gains, however there is no difference in maximal strength gains between these numbers of forced repetitions. So, forced repetitions can result in increased maximal strength, but whether their use results in greater strength gains than just carrying sets to failure remains unclear. Additionally, the long-term effects of the use of forced repetitions in very experienced weight trainers are not known. If you use forced repetitions, you should experience gains in maximal strength and you should experience no negative side effects besides probably increased muscle soreness. When using forced repetitions, make sure that you have all safety precautions in place, such as attentive spotters and the pins of a power rack in place to catch the weight if needed at the lowest point in the range of motion of an exercise.
Antianen JP, Pakarinen A, Kraemer WJ and Hakkinen K. Acute Hormonal and Neuromuscular Responses and Recovery to Forced vs. Maximum Repetitions Multiple Resistance Exercises. International Journal of Sports Medicine, 24:410-418, 2003.
Drinkwater, EJ, Lawton TW, McKenna MJ, Lindsell RP, Hunt PH and Pyne DB. Increased Number of Forced Repetitions Does Not Enhance Strength Development With Resistance Training. Journal of Strength and Conditioning Research, 21:841-847, 2007.