The Truth About Building Muscle: The Science of Strength, Size & Rep Ranges
When it comes to hitting the gym, there’s a difference between building strength and bulking up.
You can get stronger without getting bigger, and you can get bigger without necessarily getting stronger. How you should approach your workouts, then, depends on exactly what you want to achieve. As a Brookfield sports chiropractor, the fitness programs I design for my athletes can vary greatly depending on their goals.
Unfortunately, there’s no shortage of confusing literature on bodybuilding and weightlifting, much of it with very little basis in science and physiology. In this article we’re going to take a no-nonsense look at the two types muscle growth, myofibrillar hypertrophy (or “strength” hypertrophy) and sarcoplasmic hypertrophy (or “size” hypertrophy), and how to achieve each while making the most effective use of your time in the gym.
Myofibrillar hypertrophy is an increase in the amount of a muscle’s myosin and actin proteins, which are the contractile, “fast-twitch” muscle fibers, leading to an increase in strength. In other words, when you put your muscles under heavy stress through progressive overload (gradually increasing either the weight you’re lifting or the number of times you lift it), your body responds by increasing it’s ability to contract those muscles by building new contractile fibers.
Over time, the number and efficiency of the motor units called into play to perform these movements also increases, effectively allowing your body to perform them with less effort. Ultimately, the effect is an increase in the strength and neuromuscular response of the muscles, and consequently you’re able to lift heavier weights. However, it should be noted that increasing strength in this way does not necessarily lead to a visible increase in the size of the muscle.
Sarcoplasmic hypertrophy is an increase in muscle size caused by elevated levels of sarcoplasm in muscle tissue. Sacroplasm is a fluid composed of water, ATP, glycogen, and creatine phosphate that surrounds the muscle fibers. This kind of hypertrophy is achieved through slower, controlled weight lifting. These types of exercises put sustained stress on muscles, activating both the slow and fast twitch muscle fibers and depleting the muscles of energy.
It’s important to note that increasing the size of a muscle via sarcoplasmic hypertrophy does not require an increase in the amount of contractile protein in the muscle fibers. In other words, an increase in muscle size does not necessarily correlate to an increase in that muscle’s strength.
How Train For Your Goals
Whether your weight lifting routine is resulting in myofibrillar hypertrophy or sarcoplasmic hypertrophy is dependent on the length of time your muscles are under tension, and how heavy the weight causing the tension is relative to your own level of strength. This means focusing on either neuromuscular training (for strength) or metabolic training (for size).
Neuromuscular training involves using fast, explosive movements to put muscles under very heavy stress (85-100% of your one-rep maximum weight). Sets done using this technique shouldn’t last more than 40 seconds and rest periods should be anywhere from 90 seconds to five minutes.
Metabolic training, on the other hand, focuses on depleting a muscle’s energy supply. This is accomplished by using slow, controlled movements with moderately heavy weight (60-75% of your one-rep maximum weight). Sets performed in this way should generally last 40-70 seconds and rest periods should last 30-60 seconds.
Using weight that is 75-85% of your one-rep maximum will result in some combination of myofibrillar (“strength) and sarcoplasmic (“size”) hypertrophy.
How Do I Calculate My 1 Rep Maximum?
Figuring out your one rep maximum (1RM) is extremely difficult. In fact, it can even be slightly dangerous because form is likely to be compromised, especially in inexperienced lifters. As a sports chiropractor, I never recommend training with sets of less than 3 reps, even for strength.
The easiest method of finding your 1RM is to spend one or two workouts performing a single set of five to ten reps for every exercise in your routine. Make sure you are using a weight that causes you to max out on last rep and can’t manage another rep. You can then input the weight and number of reps you were able to perform for each lift into the 1RM calculator. Use the estimated one-rep max to calculate the percentages you’ll need to reach your specific goals.
Remember that the amount of weight being lifted is only one of the factors determining which type of hypertrophy is being activated. So how should you make sure the time your muscles are under tension is appropriate for your goals?
The easiest way to do this is to follow to a specific rep scheme. When performing low-rep sets, muscles will be under tension for a shorter period of time and the weight will be closer to your one-rep maximum (and therefore stimulating myofibrillar hypertrophy). Conversely, when doing higher-rep sets your muscles will be under tension for longer periods of time, and the weight will need to be significantly less than your one-rep maximum weight to allow for the higher volume (and therefore building size through sarcoplasmic hypertrophy).
Follow these rep guidelines for your specific goals:
|Rep Range||Percent of One Rep Max||Resulting Hypertrophy|
|1-5 Reps||85-100%||Mostly Myofibrillar, Minimal Sarcoplasmic|
|6-8 Reps||75-85%||Equally Myofibrillar and Sarcoplasmic|
|9-12 Reps||70-55%||Mostly Sarcoplasmic, Some Myofibrillar|
|13-15 Reps||65-70%||Mostly Sarcoplasmic, Minimal Myofibrillar|
|15+ Reps||65% And Lower||Mostly Endurance, Some Sarcoplasmic, Minimal Myofibrillar|
How To Use This Information To Meet Your Goals
First, identify what your goal is. Are you looking to get bigger or stronger, or is your goal to do some of both at the same time? Though there’s nothing wrong with any of these goals, and each has its own advantages and disadvantages.
There are very few disadvantages to training for the purpose of increasing strength, especially if you’re happy with your current size. A significant increase in strength in a short period of time is very much possible if you train and recover properly. However, high intensity strength training is stressful on the central nervous system, and overtraining can occur if you don’t take care to recover adequately. Those training primarily for strength should focus on 5×5, 6×4, and 8×3 set/rep schemes and rest for long periods between sets.
Primarily training for increasing size definitely has its benefits, but does have drawbacks as well. Those training for size, especially beginning lifters starting with minimal strength, will eventually hit a plateau due to limited strength, forcing them to focus on strength training at some point. Those training for size should primarily use set/rep schemes of 3×15, 4×12, and 5×9 with a shorter rest periods between sets. Supersets (performing multiple exercises on the same muscle group back-to-back without rest) can also be effective for stimulating sarcoplasmic hypertrophy.
Training for both strength and size can provide the benefits of both methods of training at the same time. You can approach this one of two ways. The first is the traditional strength/size optimization method, in which you progress through all the rep ranges in one workout (i.e. lifting 75% of your 1RM for 8 reps, 80% for 7 reps, and 85% for 6 reps). The second method, linear periodization, cycles through the different rep ranges over period of several weeks.
Whatever training program you use, if you want to get the most out of your training in terms of both strength and size, you need to eventually be utilizing all the rep ranges.
Of course, your muscles can’t grow if they don’t have the raw materials needed to do so. But again, so-called “experts” have made nutrition much more confusing than it should be. Try to consume a form of quick-digesting protein, such as whey, along with some high-quality carbohydrates within an hour after your workout. This is the period when your body is refilling its energy stores and actively shuttling proteins and sarcoplasm into muscles, and it’s most likely to absorb and use the nutrients during this time.
Whether your goal is to build strength or increase muscle size, it’s also essential to make sure you’re consuming enough calories in your diet throughout. If you’re not eating extra calories, your body will use any protein you take in for energy instead of building muscle. You’ll need to eat approximately 15–20% extra calories a day over your basal metabolic requirement, which you can calculate the tool to the right. Try to choose food high in protein and low in carbohydrates. The ideal macronutrient breakdown for gaining the most muscle with the least amount of fat is 40 percent carbohydrates, 30 percent protein and 30 percent fat.
If you’re not already seeing a chiropractor for regular chiropractic care, you’re missing out on a huge advantage. When even a single vertebra is misaligned, the effects are not only painful, but can also result in diminished function of the nervous system, which is required to coordinate the rest of the musculoskeletal system. When the messages being transmitted by the nervous system are even slightly affected, the results can be quite dramatic.
How dramatic? A recent study from the Journal of Chiropractic Research and Clinical Investigation looked at improvements in agility, balance, power, and speed reaction in 24 athletes without injuries over twelve weeks of regular chiropractic care compared to 22 athletes not receiving chiropractic care. After six weeks, the athletes receiving chiropractic care showed an average 10.57% improvement in agility, power, balance and speed, and after twelve weeks they demonstrated further improvement of 16.7%!
The authors stated that the data supports that “the correction of [spinal joint dysfunction] enables the body to function and perform at a higher level.” Make sure you’re getting the most out of your body; see your chiropractor.
The Bottom Line
Building muscle doesn’t have to be confusing, but it does take a little knowledge when it comes to planning your workout routine and diet to make sure you’re getting the most out of your efforts.