You’ve probably heard the phrase “high reps tone, low reps bulk” often enough to believe it’s a true physiological fact, right? Well, what if I told you that statement is wrong. In fact, what if I went on to say the opposite is true. You’d probably be quite surprised, and as a matter of fact, that is exactly the case.
Let’s examine the fact and fallacy behind this statement.
First and foremost, you’ll never see the terms “tone” or “bulk” defined in a body composition textbook, but let’s attempt to define them. Toning is a byproduct of losing fat and gaining muscle. The best definition for bulking is the building of muscle tissue while increasing (or maintaining) fat. Using these definitions, you can begin to see the issue, physiologically speaking. Doing VERY high reps (> 15 reps per set) does very little to increase muscle tissue– it increases muscular endurance more than anything. The lowest rep ranges (< 6 reps per set) also do very little to increase muscle tissue. Beyond that there is the ever-present fat component in the definitions of tone and bulk, which is related to diet more than anything else.
Rep Number and Training Adaptations:
There is a very close relationship between rep number and physical response to strength training; however, this relationship is contrary to the logic suggested by “high reps tone, low reps bulk”. Here’s a brief summary of rep ranges and their associated physical response:
• High Reps (> 15-20 per set): muscular endurance adaptations. Changes to structures inside of our muscles (enzymes, mitochondria, etc.) and fuel reserves (primary stored carbohydrate) to better facilitate repetitive contraction of the muscle. This rep range will result in fatigue resistant muscles.
• Moderate Rep (8-15 per set): muscle growth (or hypertrophic) adaptations. This rep range is perfect for inducing muscle damage, increasing anabolic (growth) hormone release, and increasing production of muscle proteins. This rep range will result in bigger muscles.
• Low Rep (< 8 per set): neurological adaptations. These are the changes to the connections between the motor parts of the brain and the muscles that allow the muscles to become stronger and more powerful. Although this is a complex process, it boils down to sending stronger nerve signals to the muscle. In most cases, this rep range results in an increase of strength or power without a corresponding increase in muscle tissue.
Take Home Message
From the explanation of training adaptations above, you can see that “high reps tone, low reps bulk” has no true merit. First, as discussed above; loss, gain, or maintenance of fat has nothing to do with rep range and very little to do with strength training. Since that is a part of the tone/bulk definition, the statement begins to sound false before you even examine the physiology of rep ranges. Once you extend the concept to that level, it becomes even less true. The highest and lowest rep ranges, respectively, do very little (if anything) to change the structure of the muscle, whereas the middle rep range (what most people consider to be slightly “higher rep”) does an excellent job of building muscle. Consider this before you step into the gym next to either tone or bulk.