How Many Reps Should I Do? Ah, the age-old question! Out of all the various training variables this is one of the most important. It’s also one of the least understood. The right number of reps has been debated for decades. There are a few studies that suggest it should be based on muscle fiber type. In this article, I will not cover that but also review rep performance. Let’s get going!
Muscle Fiber Types
In this section, we will look at the different muscle fiber types and their recruitment. Each type seems to respond best to a certain rep range. Understanding and applying this concept goes a long way in answering the frequent question: “How Many Reps Should I Do?”
There are basically three types of muscle fibers:
Slow Twitch Fibers
Type 1
These fibers contract slowly. They are predominantly endurance fibers with limited size and strength capacity. Slow twitch fibers need oxygen to function. To this end, they have a high amount of mitochondria. This aids their use of oxygen. They also have a greater number of capillaries than other muscle fiber types. This means that slow twitch fibers are better for nutrient delivery. Also, these types of fibers are endurance fibers because they are resistant to fatigue. As well, they produce a low level of force output. Therefore, they respond best to reps in the 15-20 range. (1, 2)
Fast Twitch Fibers
Fast twitch fibers are further divided into two categories: Type IIa and Type IIb. Fast twitch fibers are the ones that produce the most muscle strength. Plus, they have the best growth potential. They are the fibers that are mainly responsible for muscle size. But, they also have a slower nutrient replenishment rate because, as noted, they have less capillaries than slow twitch muscle fibers. Taking all of this into account, they respond best to reps in the 5-8 range. (1, 2)
Type IIa:
These are the muscle fibers that promote explosive power – for a very short time. This makes them ideal for weight training, especially when the lifter is using heavier compound exercises. These fibers rely on the glycolytic energy system. For those that may not know, that is an energy system that uses the method of anaerobic glycolysis to produce ATP. Compared to slow twitch fibers, type IIa fibers produce more force but are less fatigue resistant. They also contract at a faster speed than slow twitch fibers.
Type IIb:
The type IIb muscle fibers are the fastest twitch fibers. However, they also fatigue the fastest. These are the fibers responsible for the most power. In fact, they are involved in any activity that requires an all-out burst of power. They contract for a very short period of time, typically around 7.5 milliseconds. (1, 2)
Muscle Fiber Recruitment
As we answer the question of how many reps, it makes sense to look briefly at muscle fiber recruitment. Muscles produce force through the recruitment of motor units. They can be defined as a group of muscle fibers stimulated by a motor neuron. No matter what your workout intensity looks like, slow-twitch motor units are recruited first. If your workout intensity is low, these motor units might be the only ones that need to be recruited.
Now, what if your workout intensity is high? Examples include when you lift heavy weights or use intensity techniques like drop sets or supersets. In that case, the slow- twitch motor units are recruited first, then they are followed as needed by fast-twitch IIa and fast- twitch IIb.
A Reference Study
Ok, now we get to the section that talks about research.
Test Parameters
A recent research study used 8 weightlifters and 8 endurance athletes as test subjects. These subjects performed as many reps as possible using 75% of their 1RM.
Specifically, all of the test subjects were tested for the maximum weight they could perform one time on the Leg Press machine. After resting for five-minutes, they completed as many reps as they could using 75% of their 1RM.
The Results
The majority of the test subjects performed between 8 and 13 reps. This group represented individuals with a more or less even mix of Type 1 and Type 2 muscle fibers. There were a few test subjects who completed fewer than 8 repetitions. These subjects were power athletes such as sprinters and jumpers. These athletes generally have a higher amount of Type 2 (low endurance) muscle fibers.
There were a few test subjects who were able to complete more than 13 reps. These are endurance athletes such as marathoners and triathletes. These athletes tend to possess a higher percentage of Type 1 (high endurance) muscle fibers.
Let’s Recap
The results suggest that individuals who have an even mix of Type 1 and Type 2 muscle fibers might get the best results using 8-12 reps per working set. It would seem that the individuals who have predominantly Type 2 muscle fibers should get the best results by using less reps per set, for example, 5-8. Finally, individuals with predominantly Type 1 muscle fibers should get the best results if they train more reps per set, such as 15-20. (3)
At this point I want to note that I will review how to tell what your predominant muscle fiber type is soon.
Training Guidelines
Here’s how to implement the information we just reviewed.
Slow-Twitch Muscle Exercises
Lift lighter loads (below 70% 1RM) using 12-15 reps. This will be, or course, your warm-up sets and can also be 1-2 high rep pump sets done as a finisher.
Fast-Twitch Muscle Exercises
Lift heavier loads (more than 75% 1RM) using 5-8 reps.This should be, of course, the majority of your workout.
Rep Performance – Explosive Up/Slow Down/Pause & Hold The Stretch
I suggest lifting the weight explosively on the concentric phase of the rep. This approach is commonly used to help build strength and power. Some experts suggest that the explosive approach to a concentric rep recruits more fibers.
Pause and Hold
When you reach the fully stretched position, pause and hold the weight for a 4 count. In most exercises, this should be just before the bar returns to the start position, also known as the turnaround. This is where there’s a full stretch on your working muscles. For example, on the bench press, this is just before the bar touches the chest. With some exercises, such as lat pulldowns, the fully stretched position is right near the top of the rep. It’s believed that this approach is very effective for mTOR activation (which leads to protein synthesis stimulation).
Negative Emphasis
When you use a slow and controlled motion on the eccentric phase, it takes advantage of negative emphasis. That refers to a principle that dates back to Arthur Jones (probably even further). Negative emphasis suggests that the negative phase of the rep is the most critical part. The belief is that you cause more muscle damage on the negative phase.
What About Rep Tempo?
I advise using the following tempo: 2-0-4-4. That’s a 2-second concentric, 0-second pause, 4-second eccentric, and 4-second stretch position pause and hold. (4, 5, 6)
Rep Performance And mTOR Activation
Lifting weights is one of a few things that will activate mTOR. The type of training that’s currently considered to be most effective in this case is using compound exercises with progressively heavier weight. Reps in the 5-8 range are commonly suggested. Some recent studies seem to suggest taking your sets to failure, or at least near failure. Yep, another never-ending question – should I train to failure? Personally, I go to momentary failure on every working set. You can take it farther – to complete failure and beyond.
Specialized Training – Determining Your Muscle Fiber Type
So far, we have established that heavy weight on the big basics using 5-8 reps per set are very effective. However, not everyone is in a place where that approach makes sense. Your goals may be different. Therefore, to determine the right number of reps for an exercise, such as the squat for quads, simply go online and find a 1RM calculator. Using reps and weight from your last quad workout, this allows you to enter these numbers and then calculate your 1RM.
Example
Let’s say your main exercise, as indicated above, is squats. After 2-3 light warm-up sets, perform as many reps as possible using 75 percent of your calculated 1RM. This represents the number of reps you should use in this exercise.
How This Breaks Down In Terms Of Muscle Fiber Type
So, if you get 6 reps, you probably have a higher percentage of Type 2 muscle fibers. Therefore, again as suggested above, you should train using 5-8 reps per working set. At the other end of the spectrum, if you complete 13 reps, you probably have a higher percentage of Type 1 muscle fibers. Therefore, you should train with about 12 to 15 repetitions per set.
The higher reps work well for endurance athletes or very advanced bodybuilders who have reached their strength ceiling. Yep, that will eventually happen. At that point, many lifters chase the pump and/or implement intensity techniques as tools of progression.
Match Your Reps To Your Fiber Type
Overall, it seems that you will get the best size and strength results if you match your reps to your muscle fiber type. Although it’s true that muscle fiber type may vary among muscle groups, this factor seems to be relatively consistent in most people.
Regardless of your predominant muscle fiber type, the key to size and strength development is intensity. By this I mean working hard on your chosen exercises. As noted, use enough weight to fail within your target rep range. By matching the optimum rep range with your muscle type you will make safe, steady and solid progress.
Nutrition Suggestions
No article is complete without at least a brief reference to nutrition and supplementation. As always, I suggest 1 gram of protein per pound of body weight at least. I also advocate dividing this total up over several meals. Hey listen, it’s all about convenience. If you’re eating, include some protein. Carbs should be 1.5 to even 2 grams per pound of bodyweight, as long as you aren’t gaining midsection fat. That is the key to knowing if you’re overeating carbs.
Supplement Suggestions
I always suggest a few supplements especially for size and strength. Of course, we have to start with protein. My go-to is Hi-Tech Precision Protein because of its impact on leucine release and protein synthesis.
Next is a good pre-workout. One of my favorites is Alpha Supps Pre because it’s one of the new “core” type pre-workouts that have helped bring prices down to reasonable levels. Another great option is Gorilla Mind Gorilla Mode, one of the best pre-workouts you can buy.
From there, I suggest creatine monohydrate, the premier natural supplement. One of my favorites is AllMax Nutrition Creatine Monohydrate. Finally, if you really want to see hardcore results, try prohormones. Understand what you’re doing before using, however. I suggest Blackstone Labs Abnormal. Another great choice is Blackstone Labs Brutal 4ce. Make sure you use a good PCT after your cycle, I suggest 5% Nutrition Post Gear.
Summary
The answer to the question “How Many Reps Should I Do?” is clear: choose your reps according to your muscle fiber type. This will result in the most efficient training approach. What if your goals don’t match up? You can still use the rep range that fits your goals, but I suggest incorporating the range that seems to fit you best. From there, implement my nutrition and supplement suggestions, and go hit the gym!
References:
- Types of Muscle Fiber | Athlepedia, The Athletics Wiki | Fandom
- Muscle Fiber Types Body Types | Northeast Texas Community College (ntcc.edu)
- Richens, B., & Cleather, D. J. (2014). The relationship between the number of repetitions performed at given intensities is different in endurance and strength trained athletes. Biology of sport, 31(2), 157–161. https://doi.org/10.5604/20831862.1099047
- Resistance exercise initiates mechanistic target of rapamycin (mTOR) translocation and protein complex co-localisation in human skeletal muscle | Scientific Reports (nature.com)
- Cheng, J., & Du, J. (2007). Mechanical stretch simulates proliferation of venous smooth muscle cells through activation of the insulin-like growth factor-1 receptor. Arteriosclerosis, thrombosis, and vascular biology, 27(8), 1744–1751.
- Morton, R. W., Oikawa, S. Y., Wavell, C. G., Mazara, N., McGlory, C., Quadrilatero, J., Baechler, B. L., Baker, S. K., & Phillips, S. M. (2016). Neither load nor systemic hormones determine resistance training-mediated hypertrophy or strength gains in resistance-trained young men. Journal of applied physiology (Bethesda, Md.: 1985), 121(1), 129–138. https://doi.org/10.1152/japplphysiol.00154.2016