Written by Sam Coleman | Co-founder
Fact checked by Kirsten Yovino, CPT Brookbush Institute
FACT CHECKED
You walk into the gym and see someone half your size lifting almost twice as much. How does this happen? Bigger muscles aren’t necessarily the stronger muscles. In this post, we explore dense muscle vs. big muscle and how you can tailor your training to achieve both.
MUSCLES IN THE HUMAN BODY
The human body contains over 650 skeletal muscles that are mostly attached to the bones via tendons. These skeletal muscles are the muscles you train when weightlifting. The vast majority of these muscles are paired, meaning they are mirrored on both sides of the body. Muscles are usually classified into groups or compartments. Muscle groups generally work in unison to perform various movements. Every skeletal muscle has muscle tissue, connective tissue, nerve tissue, and blood or vascular tissue. Skeletal muscles come in different shapes and sizes.
There are three types of muscle in the body:
Skeletal: Skeletal muscles are responsible for the body's movement, where the central nervous system controls these movements. The skeletal muscles are composed of striated muscle fibers that move with conscious or voluntary control. There are many nuclei within the muscle fiber. The skeletal muscles are striated because of how the sarcomeres (contractile unit of muscle fiber) are structured.
Smooth: Smooth muscle is located within the walls of the hollow internal organs such as the bladder, blood vessels, and gastrointestinal tract. This muscle isn’t consciously controlled but rather is under the direction of the autonomic nervous system. This muscle has spindle-shaped cells with one central nucleus.
Cardiac: As the name suggests, cardiac muscle is located within the heart's walls and is also under the control of the autonomic nervous system. Similar to the smooth muscle, there’s one central nucleus. It is striated like skeletal muscle and has rectangular-shaped cells.
In this post, we’re focusing on skeletal muscles since these are the ones you’re trying to build through weight-bearing exercise.
WHAT IS MUSCLE FIBER?
Skeletal muscle fibers are cylindrical. Connective tissues cover these muscle fibers called the endomysium. Skeletal muscles can consist of thousands of muscle fibers that are bundled. These bundles of muscle fibers are then covered by connective tissue called the epimysium. Connective tissue or fascia wraps the epimysium, which creates the separation between muscles. The bundles of muscle fibers are called fasciculus and are surrounded by connective tissue named the perimysium.
Muscle fibers are created from a process of myogenesis where myoblasts are fused, which leads to long multinucleated cells (muscle fibers). These muscle fibers are comprised of myofibrils which are made of actin and myosin filaments. Together these are called myofilaments which build units called sarcomeres. Finally, these sarcomeres are the units that provide the capability of muscle contraction.
The connective tissues protect the muscle fibers, which are pliable. The connective tissue also allows for blood vessels and nerves that contribute to the contraction of the muscle. Skeletal muscles often converge into tendons or aponeurosis (dense connective tissue). The tendon or aponeurosis creates indirect attachments to bones or other muscles via connective tissue.
Skeletal muscles often cross joints and are attached to both ends via tendons. Human movement occurs when one bone stays relatively stable or fixed when the other end moves due to muscle contraction.
Skeletal muscles contract once they receive a signal from a nerve cell impulse. To power the skeletal muscles, fats and carbohydrates are oxidized, and, in some cases, anaerobic chemical reactions are used by fast-twitch muscle fibers. ATP (adenosine triphosphate) molecules are created by these chemical reactions that result in the movement of the myosin heads of the muscle fiber.
FAST TWITCH VS SLOW TWITCH MUSCLE FIBER
Skeletal muscles are made of two types of muscle fibers; fast-twitch and slow-twitch. These muscle fibers have different functions that are important to recognize when training. Skeletal muscles have a mixture of both types of muscle fibers but the ratio can change depending on the age or training program of the individual plus the general functioning of the muscle in question.
Fast-twitch Muscle Fibers: These muscle fibers produce explosive power and force but tire quickly. They’re more anerobic and have less blood supply than slow-twitch fibers so they are sometimes referred to as type II or white fibers. Explosive exercise such as plyometrics or weight lifting recruit fast-twitch muscle fibers.
Overall, fast-twitch muscle fibers are larger but have less capillaries, mitochondria and myoglobin than slow-twitch fibers so they get tired faster. There are two types of fast-twitch muscle fibers; Type IIX and Type IIA. Type IIX also referred to as type IIB are more powerful and explosive than TypeIIA but they’re less efficient. TypeIIA also called intermediate muscle fibers are a combination of type 1 (slow-twitch) and typeIIX. Therefore, typeIIA can use both anaerobic and aerobic energy which leads them to have a higher endurance capacity compared with typeIIX.
Slow-twitch Muscle Fibers: These muscle fibers are aerobic and are able to withstand longer duration of workload without fatiguing. Slow-twitch fiber have more myoglobin and mitochondria than fast-twitch fibers and are sometimes called type I or red fibers because of the increased blood supply. Steady state exercise like long distance running relies on slow-twitch muscle fiber to power you through. Slow-twitch muscle fibers are generally smaller than fast-twitch fibers with more capillaries making them ideal for aerobic exercise. These slow-twitch fibers produce less overall force but are vital for stability and postural control.
We all have muscles with a mixture of fast-twitch and slow-twitch fibers but if you want to increase one or the other you must cater your training to the type of muscle fiber you want. If you want to increase your fast-twitch muscle fiber you should center your training around explosive, powerful movements. If you want to increase your slow-twitch fibers then you should base your training on endurance activities.
Note: As we age, we lose fast-twitch muscle fiber while we increase slow-twitch fibers.
HOW DOES MUSCLE GROW?
To achieve muscle hypertrophy, aka growing bigger muscles, a few physiological processes need to take place. First, resistance training injures or damages the cellular proteins in skeletal muscles, activating satellite cells to repair the damaged cell. Then, AFTER a workout, the damaged muscle fibers are replaced and fused to create new muscle protein strands (myofibrils). By increasing the number or thickness of these myofibrils, the size of the muscle will grow. However, this muscle growth or hypertrophy can only happen if the muscle protein synthesis rate is more significant than muscle protein breakdown.
Satellite cells help skeletal muscle grow when they’re activated, they increase the nuclei to the muscle cells, which makes the muscle cells grow. You can increase the satellite cell content and activation through resistance training, according to this study.
It’s important to note that satellite cells aren’t entirely understood how they affect muscle growth across the general population. However, this study showed that there are some extreme differences in how some people respond to resistance training. Participants performed 16 weeks of knee extensor exercise. At the extreme end, people achieved 58% myofiber hypertrophy with 23% satellite cell activation. In the middle, people saw an increase of 28% hypertrophy and 19% satellite cell activation, and the low end saw 0% in both areas.
TYPES OF MUSCLE GROWTH
Not all muscle growth is created equal. There are two general types of muscle growth:
Myofibrillar Growth: Myofiber hypertrophy is precisely as it sounds; this is when you increase the muscle's thickness or number of myofibers. To achieve this growth, you must follow the progressive overload principle, where the volume lifted increases incrementally over time. By increasing the stress or tension on the muscles, satellite cells and mTOR (protein complex that regulates growth) are activated. Muscle damage is another way of activating satellite cells that enable myofiber growth. The soreness you feel after you work out is the acute muscle damage that triggers the release of inflammatory molecules and immune system cells to activate the satellite cells.
Sarcoplasmic Growth: Sarcoplasmic growth is due to metabolic stress on the muscle that causes swelling around the muscle without increasing the size of the muscle cells. This metabolic stress is showcased when you feel that “pump” in the gym. Sarcoplasmic muscle growth results in bigger muscles, without necessarily improving strength. The growth is mainly due to added glycogen and muscle cell fluid that enlarges the muscle while making the connective tissue bigger.
Note: The other significant factors to consider when covering how muscles grow are hormones. Hormones such as Insulin Growth Factor (IGF-1) and testosterone play a massive role in muscle growth and repair. For example, IGF-1 activates satellite cells and supports muscle mass growth by improving protein synthesis and funneling amino acids to muscles while regulating glucose intake.
Testosterone helps with muscle protein synthesis, slows protein breakdown, activates satellite cells, and rouses other anabolic hormones. It’s important to note that resistance training has similar effects on men and women activating satellite cells. Still, women lack the testosterone to build muscle at the same rate as men.
Other growth factors produce muscle growth, such as hepatocyte growth factor (HGF) and fibroblast growth factor (FGF). HGF is thought to regulate the satellite cells sent to the damaged muscle, while FGF may help form new blood capillaries.
Lastly, growth hormone is released from the pituitary gland due to the stimulation of resistance training. Growth hormone assists in the uptake and repartitioning of amino acids into the skeletal muscle and aids in stimulating fat metabolism for energy use during the muscle growth process.
WHAT IS DENSE MUSCLE?
Dense muscle is skeletal muscle that has more muscle fiber growth within the muscle than the amount of fatty tissue. A smaller, denser muscle is stronger and can lift more weight than a larger muscle with less muscle density. When it comes to dense muscle, you can think of powerlifters that appear much smaller and weaker than bodybuilders but are much stronger in relative terms. This is because powerlifters tend to get stronger through myofibrillar hypertrophy, where more myofibrils are created in the muscle, making it denser.
WHAT IS BIG MUSCLE?
Big muscle refers to muscle mass or the overall size of the muscle. Again, referring back to the point above, this can be closely related to sarcoplasmic hypertrophy. The muscles grow due to the increased tissue and muscle cell fluid without necessarily improving the strength capacity. In this case, you can look at many bodybuilders who don’t focus on strength training but rather muscle size or hypertrophy.
TRAINING FOR DENSE MUSCLE VS BIG MUSCLE
To understand the difference between dense and big muscle is to look at the relative strength of muscle fibers which is called specific tension. Specific tension equals maximal force divided by cross-sectional area. This study looked at the specific tension of bodybuilders, power athletes, and untrained people. The results showed that bodybuilders had 65% less than the power athletes and even 41% less than the untrained people.
One surprising result showed that the peak power of bodybuilders was similar to the untrained control group and 58% lower compared to power athletes. The research suggests that high-intensity, low-volume resistance training paired with aerobic exercise enhances peak power while low to moderate intensity high-volume resistance training doesn’t affect peak power and even leads to a lower specific tension. The researchers theorize that this is due to the differences in myofibrillar density and/or changes in contractile proteins.
Another in-depth study showed that contractile force or single muscle fibers grew with muscle fiber grew with fiber diameter, not cross-sectional area. To sum it up, this generally means that specific tension decreases as overall fiber size increases.
HOW TO TRAIN FOR DENSE MUSCLE:
Several factors come into play, such as fitness level, body composition, gender, diet, and hormones to build dense muscle. To give yourself the best shot of building strong, dense musculature is to train like a powerlifter or power athlete. Here are a few tips you can use to help gain denser muscle:
Low Rep Ranges: When training to build strength and power, you should focus on using a low volume, high-intensity approach. Stick within 1-6 reps for the main compound lifts such as the deadlift, squat, bench press, and overhead press.
Increase Time Under Tension: You’ll be lifting lower overall reps when trying to build dense muscles. Therefore, to maximize the reps, you should focus on increasing the quality and intensity of each rep. One way to do this is to slow down the eccentric or negative phase of the lift. For example, try to explode on the concentric phase, then slow down the negative to 1-3 seconds.
Focus on Compound Lifts: Base your training around the big lifts such as squats, power cleans, deadlifts, and bench presses. Try the famous 5 x 5 stronglifts training program to increase strength or a powerbuilding workout program that allows for both core and accessory lifts.
Take Longer Rests: Take 2-5 minutes between sets so that you can produce as much power as possible for your working sets. This added rest time will give you time to recoup as you should be lifting above your 80% one rep max for each rep.
Track Progress: To increase the weight you’re lifting; you need to have a benchmark where you started. Try to increase the weight and/or the number of reps you’re lifting over time.
Increase Protein Intake: To build dense muscle, you must provide your body with enough protein to rebuild and repair the damaged muscle fiber. The general rule of thumb is to eat 1 gram of protein per pound of bodyweight.
Don’t Overtrain: Your body needs adequate resting time so that the muscles you worked can recover. So even if you’re training six days a week, don’t train the same muscle groups on back-to-back days, with abs being an exception. You can hit each muscle group twice a week with a total of 10-20 sets.
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HOW TO TRAIN FOR BIG MUSCLE:
Train Through Full ROM: To build bigger muscles, you should work them through an entire range of motion. Moving the muscles through a wide range of motion works the muscle fibers at various lengths. This can produce more muscle damage and more potential for hypertrophy.
Use Moderate/High Rep Ranges: Hypertrophy rep ranges have a much larger delta than power and strength rep ranges. Sarcoplasmic hypertrophy can be achieved within 6-40 reps, but the sweet spot for overall strength and hypertrophy is 6-12 reps.
Use Shorter Rests: Rest times when aiming to gain muscle size should be 1-2 minutes. It’s important to keep the blood in the muscles to lengthen the “pumped” time. This may also release more growth hormone in the body.
Use Lighter Weights: When training for muscle hypertrophy, you’ll be working in the 6-12 rep range. This means you should be using weights that are 65-80% of your one-rep max.
More Accessory Exercises: If the end goal is to gain muscle size, you’ll probably need to work on more isolation exercises. Instead of basing each workout session around one main compound exercise, you have a little more freedom regarding exercise selection.
Eat Enough Protein: Similar to building dense muscle; you must consume enough protein to sustain muscle growth. You can supplement your diet with protein shakes, whether they’re whey or plant-based.
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ARE DENSE MUSCLES BETTER THAN BIG MUSCLES?
Dense muscles aren’t better or worse than big muscles. Training for dense muscle or big muscle comes down to your end goals. Do you want to become more powerful? Do you want to improve athletic performance? If you answered yes to those questions, you might want to train for dense muscles, which means heavier weights, lower reps, and more focus on compound movements. On the other hand, if your end goal is to build a great physique, you might want to train for hypertrophy or bigger muscles.
We always believe it’s best to have a good mix of dense muscles that look good. Therefore, we center our training around the essential compound movements and mix in some isolation exercises. You can try our PHAT program or PHUL workout program to get the best of both worlds.
CAN SMALLER MUSCLES BE STRONGER THAN BIGGER MUSCLES?
Yes, smaller, more dense skeletal muscles can be stronger than bigger muscles. The best course of action is to train for both strength and hypertrophy. Try to hit each muscle group twice a week with up to 20 sets per muscle weekly. Stick within a 6-12 rep range, and make sure to make the core compound lifts are the cornerstone of your training.
HOW DO I GET STRONGER WITHOUT GETTING BIGGER?
To get stronger without getting bigger, you can do the following:
- Lift heavier weights for lower total sets and reps.
- Do more explosive work like plyometrics to help build lean muscle while you burn calories.
- Incorporate more stability training and core training into your workout.
- Focus your training around the core lifts of bench, deadlift, squat and overhead press.
WHY DO I GAIN STRENGTH BUT NOT SIZE?
There can be multiple reasons why you might be experiencing strength gains without adding size. First, your body adapts to the stress placed on it and becomes more efficient in using the muscle mass that you currently have. This might be the situation you find yourself in.
If you’re weight training with good consistency of three times a week and hitting every muscle group at least once a week, then you might not be training in the proper rep ranges. On the other hand, if you’re only training for power or endurance, you might not see any hypertrophy or muscle gain.
However, the more common reason you might be getting stronger without gaining muscle mass comes down to your diet. If you’re not consuming enough calories or you’re only eating at maintenance levels, then your body doesn’t have enough fuel to realize any muscle gains. If this is the case, you need to figure out your TDEE (total daily energy expenditure) and add at least 10-20% to this until you start seeing some progress. It’s also paramount to get enough protein to build muscle mass. Shoot for 1 gram of protein per pound of bodyweight.
FINAL NOTE
It’s not so much dense muscle vs big muscle and whether one is superior to the other. Instead, like in all things fitness, you should consider your end goals. If you want dense, powerful muscle train the big compound movements with heavyweight 80-95% of your one-rep max in sets less than six reps. Suppose you want big, well-built muscle, train with a mixture of compound movements and isolation exercises with weights in 60-85% of your one-rep max with sets of 6-12 reps. Or better yet, train for both dense and big muscle by combining both training modalities. Either way, make sure you get enough rest, calories, and protein to aid in your quest for gains.
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