by Chad Kerksick PhD June 29, 2012 4 min read
Exercise scientists continue to explore a number of ways in which performance can be improved. Key variables exist that resistance training athletes must consider and be able to manipulate in a positive fashion to improve their performance (Spiering 2008). These variables include intensity or the amount of weight you are actually lifting. Arguably this variable is the most important and should go up and down as you progress through a resistance training program. The frequency of your workouts or how many workouts you complete each week is another variable to consider. For many bodybuilding athletes, frequency commonly ranges from two to six as this variable should reflect your desire and interest in resistance training and how much time you can prioritize for your exercise program; a common frequency prescription is two three resistance training workouts each week. The order of exercises is important and frequently exercises which utilize the greatest amount of muscle are performed before exercises that incorporated a smaller number of muscle groups and/or small muscle groups overall. Exercise volume is a critical variable that reflects the total combination of how many sets, how many reps and how much weight you are using for your workouts. As people desire to achieve greater fitness benefits, exercise volume needs to progressively be increased. The final variable is rest and commonly rest is considered to be the amount of rest taken between each set of exercise. Individuals who desire to promote more hypertrophy or have quicker workouts will rest between 30 and 90 seconds. As maximal strength and power become important, the amount of rest taken between sets should be increased commonly from around two to three minutes to as much five to eight minutes between sets. Greater rest allows for greater recovery and an improved quality of effort. Scientists from Appalachian State University in Boone, NC recently published a paper in the Journal of Strength and Conditioning Research that highlighted another consideration: the amount of rest between repetitions (Hardee 2012).
This is an interesting study idea because as mentioned previously the most common consideration for rest is the amount taken between sets, not repetitions. However, maximal quality of effort is an important outcome for any strength and power athlete or weightlifter. When training with typical sets and reps schemes of multiple sets of 4 – 8 repetitions with minutes of rest between sets at intensities intended to promote fatigue as well as strength and power development, the quality of the first repetition compared to the final repetition could be drastically different. Using this study design, the authors had young college males who were already familiar with resistance training complete three different training sessions which all consisted of 3 sets of 6 repetitions with the power clean exercise at 80% of their one-repetition maximum. The volume, exercise choice and intensity prescription all remained the same, but one condition provided no rest between reps, another 20 seconds of rest between reps and finally another provided 40 seconds of rest between each repetition. To minimize confounding effects, the conditions were performed in a randomized order and all three conditions were separated by at least 72 hours. With a platform under their feet to measure force and power, the results were exactly what you would expect. As the amount of rest between repetitions increased, the percentage of decline in force, power and velocity went down.
For example, peak power decreased by nearly 16% when no rest was provided but decreased by 5.5% and only 3.3% when 20 and 40 seconds of rest, respectively were taken between each repetition. Similarly, peak force decreased by 7.3% from the first repetition to the sixth repetition with no rest but only decreased by 2.7% and 0.4% when 20 and 40 seconds of rest were provided between each repetition. Peak velocity showed an identical pattern as well where velocity decreased 10.2% with no rest, 3.8% with 20 seconds of rest and 1.7% with 40 seconds of rest between repetitions. As can be seen from these results, providing more rest between repetitions may be a strategy to consider, particularly as individuals become interested in making sure the body is better recovered to perform maximally.
How can this type of training be useful? Well for starters, maximal strength and power are very much about quality of effort; more rest allows for a higher quality effort. From a physiological perspective, strength and power are simply about how effectively and efficiently the body is able to recruit the highest number of muscle fibers to contract at the proper time to result in peak force and power levels. Hypertrophy, on the other hand, depends more on quantity of lifting as maximal volume, fatigue and intensity become critical to hypertrophy. This type of training may allow a person to use 2-3% more weight through a typical set and still be able to complete very high quality movements. When translated over the course of several weeks, it seems likely that greater improvements in strength and power could result.
It would be important for a person to also be aware of the added amount of time this type of training would likely create when compared to performing traditional amounts of rest between repetitions. In this light, maybe a person who is going through a strength and power phase only allows more rest between reps for primary or core exercise such as bench press, squat, leg press, cleans, deadlifts, etc. and isolation or single-joint exercises are completely in a more traditional fashion. All in all, this is a really cool study that allows people to see that the world of exercise science is still very new and being open-minded and creative with foundational variables such as intensity, choice, frequency, order, volume and rest can allow for greater improvements in your workouts.
Spiering, B. A., W. J. Kraemer, et al. (2008). “Resistance exercise biology: manipulation of resistance exercise programme variables determines the responses of cellular and molecular signalling pathways.” Sports Med 38(7): 527-540.
Hardee, JP, Triplett TN, Utter AC, Zwetsloot KA, Mcbride JM. Effect of Interrepetition Rest on Power Output in the Power Clean. J Strength Cond Res. 26(4):883-889, April 2012.