Sports Physiologist Dr. Mike Israetel is the go-to training expert on the Renaissance Periodization YouTube channel, often dissecting what the latest research suggests for resistance training. On Dec. 12, 2023, Dr. Israetel spoke to the often-touted debate about whether lifting heavy weights for fewer reps while bulking and lifting lighter weights for higher reps for cutting are accurate training methodologies or just a fun balance of words.
Per Dr. Israetel, the science suggests that both training styles can build equivalent muscle over time. See the full breakdown and Israetel’s recommendations below:
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Debunking Traditional Approaches to Bulking & Cutting
Bodybuilders, Strongmen, and other gym-goers alike may have heard through the fitness grapevine that one should lift heavy weights in low rep ranges to pack on muscle mass and lift lighter weights with higher repetitions to reduce body fat. Unfortunately, according to Dr. Mike Israetel, it’s not that simple.
Lifting heavy refers to sets that reach failure in the five to 12 rep range. Lifting lighter refers to sets where failure is closer to 20 reps. Both rep ranges can result in a sufficient muscle stimulus if the lifter takes their sets to near failure, meaning they fail to finish a rep or their form becomes compromised due to fatigue.
Sets of five to 30 repetitions, and even a little bit outside those ranges, have been shown in almost every study…to just not be reliably differentiable in muscle growth.
The Journal of Strength and Conditioning Research supports Dr. Israetel’s assessment. A 2015 study found that low- and high-load resistance training elicited similar responses in muscle hypertrophy. However, heavier loads yielded more strength gains. (1)
This is good news for a routine gym-goer because it suggests that building muscle allows for variety. Rep ranges can be adjusted per muscle group to optimize recovery time.
How Muscles Work
Common fitness myths like the “higher-rep, lower-weight sets help with muscle details” are tenets society needs to leave behind. There is no science that supports higher-rep training with lighter weights adds more muscle detail, whatever that might mean.
There’s also a common belief that higher reps burn more calories. Dr. Israetel says that while this might be true, the actual caloric difference is infinitesimal. Diet is how lifters can make caloric alterations to the greatest effect. For fat loss, the primary goal in the gym is to preserve as much muscle as possible while in a caloric deficit.
Although Dr. Israetel debunks the notion of lifting heavy to bulk and lifting light to cut, those methodologies can be useful tools when implemented appropriately:
- Using higher repetitions during a bulk could lead to burnout, which lifters obviously want to avoid. Through that lens, lifting in a lower rep range with heavier weights could be more optimal for recovery purposes.
- Lifting heavy during a cut might lead to a higher risk of injury as the body is training with less energy (i.e., fewer calories). Through that lens, lifting lighter weights at higher rep ranges might be safer and more effective.
At the end of a cut, Dr. Israetel suggests training at higher reps to avoid unnecessary health risks and potentially continue to hit PRs with lower weights. The psychological benefit can help lead to a successful cut.
Choosing the rep range should come from the stimulus-to-fatigue ratio that a rep range implies.
In short, choose the rep range that offers the most stimuli with the least fatigue. This is determined through trial and error, and differs for each exercise and muscle group.
Sometimes, there might not be a noticable difference between five reps or 20 reps in terms of stimulus. By testing various rep ranges to determine which stimulate the target muscles without compromising the rest of the body, lifters can create more comprehensive training plans, whether cutting or bulking.
Dr. Israetel recommended adding reps rather than weight at the end of a cut for progressive overload. This aids safety when a lifter is at their leanest.
Dr. Israetel wants people to avoid being dogmatic about the so-called science that’s passed around in the gym and abide by what the actual research suggests when training in a bulk or cut.
Reference
Schoenfeld, B. J., Peterson, M. D., Ogborn, D., Contreras, B., & Sonmez, G. T. (2015). Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men. Journal of strength and conditioning research, 29(10), 2954–2963. https://doi.org/10.1519/JSC.0000000000000958
Featured image: @drmikeisraetel on Instagram
