The most common workload prescribed in resistance training is sets of 10. Why is this so common? Who came up with this, and is this prescription what you really need to see results? Resistance training is a form of anaerobic interval training, with periods of high intensity followed by rest. The level of intensity of an exercise can be manipulated by adjusting the amount of repetitions, the amount of weight, and the ratio of work to rest. There are unlimited possibilities for the combinations you can create to reach your goals, but today let’s focus on the time vs reps aspect of an interval.
If you were to time a set of 10 controlled repetitions of an exercise, you will find that it takes between 30-40 seconds to complete the set. The resistance should be high enough that you can only complete 10 reps under control. We will consider this 10 rep max to be 100% intensity. If you think about your anaerobic energy systems, the glycolytic energy production pathways provide energy for high intensity activities lasting up to 60s. The perceived level of exertion will increase as the set goes on. This is due to the energy pathways waning as they are depleted of essential molecules. The key thing to take away from this is that in one set you are working at a maximum intensity to complete the given amount of reps.
When comparing intensity vs time, the 30 second interval allows for the most time spent above 100% intensity (VO2 max). Shorter intervals result in not enough time above 100% for maximal results, and longer intervals cannot maintain 100% intensity, so 30s seems to be the middle of the road. In resistance training there are many benefits of working at max intensity for 30 seconds, however this can be manipulated based on the desired adaption. The 30-40 second work interval will work well for goals that include gaining strength and lean muscle. This can be applied to virtually all fitness programs, which are part of why the set of 10 is so standard.
A strength athlete will benefit more from lifting heavier loads for few repetitions (1RM- 6RM). A hypertrophy athlete will benefit more from lighter loads for more repetitions (12-20RM). An endurance athlete will benefit from even lighter loads at even more repetitions (20+reps until failure). The point is that you can tailor the interval and intensity to work on a specific goal and you can vary the intensity between workouts, and between exercise cycles/phases. When choosing a workload, remember the SAID principle, which states that there is a Specific Adaptation for the Imposed Demand.
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