The hardest muscle to grow is debated, although most will agree some of the peskiest muscles include the calves, forearms, hamstrings, abs and shoulders; but why is this and what’s the best way to work out those troublesome muscles that just don’t seem to grow?9
While the reason some muscles are harder to grow, and the approach to sufficiently work them out varies, knowing the hardest muscle to grow vs the easiest muscle to grow ensures that the stubborn muscles are thoroughly worked, and not too much time or effort is spent on the ones that require little effort to grow.
With this in mind, a full list of muscles on both ends of the spectrum reveals which muscles are hardest to grow and more importantly, what you can do to grow those muscles.
Which Muscles Are the Hardest to Grow? What Muscles Grow the Slowest?
A common curiosity is which muscles are the hardest to grow or which muscles grow the slowest. Certain muscles are hard to grow, and this is among all lifters, even those with good genetics. Granted, among these ‘harder’ muscles to grow, there are those that will develop them at a faster rate than other lifters—they will still be relatively harder to grow than other parts of their body.
They include calves, abs, triceps, and oblique muscles.
The calf muscles are easily one of the hardest muscles to grow in the body, and the primary reason is that they are a heavily used muscle group. Calf muscles are highly used in daily activities such as walking or running—this has the implication that they have received adequate growth to handle this daily load, and achieving hypertrophy (muscle growth) further is challenging.
Since they are heavily employed most of the day, they have also developed endurance to allow them to function without much fatigue, otherwise rendering them inefficient. As a result, calf muscles have a particular class of muscle fibers to handle this endurance, known as slow-twitch fibers (accounting for half the muscle). This class enables prolonged use but is a challenging class of muscle to grow as opposed to fast-twitch fibers.1
The forearm muscle of the arm can be viewed as equal to the calf muscle of the leg. It consists of the following:
- Brachioradialis—responsible for flexing the forearm at the elbow.
- Forearm flexors—these move the bones of the arm on a vertical plane.
- Wrist flexors—contribute to the movement of the wrist.
Essentially, the forearm enables individuals to have a grip, and like the calf, muscles are used in everyday activities and thus contain a high number of slow-twitch muscle fibers, which are harder to grow. This makes it difficult to grow.
The abdominals or abs are widely known as one of the hardest muscles to grow in the body. They make up part of the core muscles, which include the back and the hips. Abdominal muscles are composed of transversus abdominis, pyramidalis, external obliques, internal obliques and rectus abdominis.2
Abs are not a difficult muscle to target and grow, and numerous exercises can help a lifter isolate them and develop them. They are a coveted muscle group, and well-defined abs invoke strength and perfection as an athlete— what makes them challenging to grow is that this area of the body is where a good chunk of fat is stored. This makes them not visible and frustrates many lifters trying to develop them.
Composed of two muscles named the brachialis (flexes the forearm) and biceps brachii (composed of long and short heads of biceps), this muscle is responsible for moving (flexing) the forearm towards the upper part of the arm and rotating it outwards. Biceps are one of the most sought-after muscle groups, with lifters spending countless hours exercising with little results.
As the bicep muscle accounts for several different movements, lifters don’t hit all the muscles or concentrate on just one muscle section. Gunners are often overtrained since the pulling exercises of the upper body recruit them—isolating them through curls often fatigues them.
#5 Shoulders or Delts
The shoulder muscles, also known as the delts, are composed of the front, rear, and side delts and are one of the hardest muscles to grow. They are employed in moving the arm away from the torso towards the side, rear, and forward. There are 3 primary reasons why the delts are a hard muscle to grow:
- Shoulders don’t get enough love from lifters—the delts are often reduced to unimportant muscles compared to larger groups such as the back or legs and don’t receive enough volume.
- Heavyweights—many lifters let ego get in their way and use heavy weights that compromise their form (such as arching the back when pressing), resulting in a low activation of the muscles.
- Ineffective activation of the side delts—most individuals fail to activate the side delts as they do not incorporate exercises that would work for them.
Hamstring muscles at the back of the leg move the leg towards the rear and stabilize the knee joint during squats. They are surprisingly the most powerful muscles, along with the glutes.
Just like the delts, the hamstrings do not get the attention needed to make them grow—other lifters ignore them or are ignorant of their use. Since the muscle is enormous with a lot of potentials, it requires heavy volume to be stimulated to grow. Individuals tend to work the hamstrings with inadequate form leading to a lackluster activation.
#7 Pecs or Chest Muscles
The chest muscles known as the pecs are composed of the pectoralis major and pectoralis minor with the former occupying majority of the chest and the latter straddling underneath it. The pecs are responsible for moving the arms toward the center of the torso.
Pecs are one of the most popular muscle groups—everybody wants a bulging chest. Lifters have difficulty growing them primarily due to incorrect forms. Bad form will lead to the triceps and rear delts taking most of the load.
The second reason is that lifters do not include enough variation, leading to improper activation of this large muscle, which is further grouped into upper, mid, and lower pecs.
How to Build & Train Those Pesky Muscles That Are Difficult to Grow
Fortunately, lifters can subdue these challenging and pesky muscles that are difficult to grow by increasing volume or frequency to stimulate their growth adequately. It doesn’t matter if it is a powerlifter physique vs a bodybuilder physique, these cues will apply to both sets of gym goers. Here is a full list with pics of cues to address the stubborn muscles.
Increase the Volume & Frequency on Calf Raises But Use Heavy Weight (Hardest Muscle to Grow With Light Weight)
While deadlifts and back squats stimulate the calf muscles, they are insufficient to provide adequate stimulation. Lifters should include calf raises into their regimen using machines or free weights. Increasing the volume and frequency should stimulate them and should ideally be done on machines since balancing is taken out of the equation allowing an effective mind-muscle connection.
Ending the Workout With Forearm Wrist Curls and Seated Barbell Curls
Lifters should only work out the forearms after doing compound work due to their extensive recruitment and not before. Forearm muscles can be isolated with either overhand or underhand wrist curls.
Seated barbell curls are great at developing forearms and performing 10-20 reps for each set to encourage hypertrophy. Lifters wondering why does my forearm hurt when I curl can experiment with different bars and wrist positions.
Lean Down and Vary Exercises Targeting the Abs
A lifter needs to observe their nutrition and ensure the proper diet to reduce the fat around the torso area that is obscuring the abs.
Secondly, since the abs are one of the hardest muscles to grow, they will need to be worked in different ways to effectively target them, ensuring that the upper abs, lower abs, and obliques on the side are isolated, which should give a result similar to a peloton strength before and after transformation.
Exercises that need to be performed include:
- Leg raises that target the lower abs
- Weighted crunch targeting the upper abs
- Side-bends and Russian twist ideal for isolating the obliques
- Compound exercises
Compound Pulling Work and Limit Overtraining Biceps
Lifters should ensure they are not overtraining their biceps by limiting the number of curls. Including compound pulling exercises are sure to fire up the biceps and stimulate them effectively. These include rows and pull-ups which are sure to harden muscles.
Hit the Delts With Proper Form and Ideal Weight
Shoulders should also be stimulated with lightweight to ensure that the exercise is done in good form since they are not large muscles and do not require heavy loading. Lateral raises, in particular, need to be done with weights that are lightweight. Increasing volume coupled with light weights would be ideal, and performing 12-15 repetitions in every set with optimal form will go a long way in activating them.
Increase Compound Movements and Smaller Isolation Exercises to Target Hamstrings
Compound movements such as back squats, deadlifts, or lunges will go a long way to developing the hamstrings. Deadlifts and stiff-legged deadlifts highly recruit the hamstrings enabling their activation which is only a partial answer to “where should you feel deadlifts?”, because it should be felt in the posterior chain as well.
Isolation movements that target the hamstrings, such as leg and hamstring curls, will need to be included in the regimen. They should be done with a daily undulating periodization—varying both volume and intensity—low reps with heavy weights should be alternated with high reps and lightweight.
The hamstrings have an even mix of fast-twitch, and slow-twitch muscles, and this technique ensures an efficient workout no matter if dumbbells, barbells, kettle bells or even smith machines are used. And for those asking “are smith machines bad?”, just know they can work but free weight movements are more stimulating.
Increase the Volume & Go Heavy on Bench Presses + Good Form
Lifters will need to go heavy on bench presses performing 8-12 repetitions for every set—barbells, and dumbbells. The pecs will need to be properly targeted with good form cues such as arching the back, ensuring the shoulders are tucked in, upper back driven into the bench, and bench press leg drive used to provide a stable foundation to press the bar upwards in an optimal bench press bar path.3
In addition, knowing where the bar should touch the chest on bench press will also ensure good form and proper bar path are adhered to.
Supplementary exercises such as chest fly can be done at lightweight and with high volume (12-15 reps). These should be performed at the end of the heavy bench press to increase the blood flow and when the question is asked, how many people can bench 225, Lifters who alter their routine to ensure hypertrophy of their pecs will be one of the few.
Individuals should consider reps in reserve (RIR). What is RIR in lifting? Reps in reserve are the number of reps a lifter can still do before reaching technical failure. Maximizing the reps is a good thing to encourage hypertrophy but should not always be done—lifters will need to pay attention to their RIR.
What Are the Easiest Muscles to Grow? Which Muscles Grow Fastest?
As some muscles are difficult to grow, there are conversely easier muscles to grow, and they typically grow the fastest. They usually don’t require that much volume, even without garnering much attention from the lifter.
The glutes—gluteus maximus is located in the buttocks and is the largest muscle in the human body.4 It is a primary pillar in lower body workouts driving the hips outwards and lowering the legs to the rear in movements such as back squats and deadlifts. Since these compound movements are included in the regimens of many lifters, they are activated sufficiently enough to stimulate growth as long as there is heavy lifting.
#2 Trapezius Aka Traps
The traps, which are essentially the majority of the back muscles, are easily the most worked-out body part. These muscles stabilize the shoulders during movement of the upper arm. Compound exercises, especially the deadlifts and rows, are sufficient to grow the traps, with most lifters not needing any specific isolation exercises to develop them.
In addition, both presses—bench and shoulder recruit this muscle group to stabilize the movements, which further catalyzes hypertrophy. The highly desirable “neck flare” (a chunk of muscle that bridges the neck and shoulders) becomes apparent due to compound movements.
#3 Monster Quads
This muscle group makes up a good proportion of the leg and is among the largest muscles. They stabilize the body and are recruited for the movement of the knees and hips.
Quads develop easily and quickly because they are the primary driving force in lower body workouts, ensuring maximum activation. Monster quads are usually seen in the top 10 bodybuilders of all time and are very well defined. They are certainly not the hardest muscle to grow.
#4 Latissimus Dorsi Aka Lats
The traps are located on the back side and constitute the lower back. Their activation implies arm adduction—the arms pulling towards the torso while being lowered down. Lats are usually employed during many exercises; however, to stimulate efficient hypertrophy, they will need to be targeted through exercises such as pull-ups and chin-ups as they are pretty tricky to isolate.
They are, however, very responsive to these exercises and will develop quickly. The tapered V-shape is coveted by many lifters and is caused by the flaring out due to developed lat muscles.
Rhomboids are located in the middle of the upper back adjacent to the shoulder blades and have the function of pulling the shoulder scapula (blades) together. They give the back a distinctively thick look since they are at the center. Their location implies that they are challenging to isolate. Compound exercises done heavy and with good form will sufficiently catalyze the rhomboids to hypertrophy.
#6 Spinal Erectors
These muscles line the spinal column and are recruited for an ideal posture or when extending the back. Spinal erectors provide for a strong core which translates into the lifter’s ability to haul weight. Spinal erectors are automatically activated during back exercises such as deadlifts and don’t need to be especially isolated. A majority of back exercises recruit these muscles to maintain a neutral spine and provide stabilization which makes them easily grow and not the hardest muscle to grow.
The triceps are responsible for extending the forearm at the elbow and are the biggest muscle in the upper arm consisting of 60% of it.5 This muscle is often neglected by novice lifters which is a shame because it easily responds to stimulation to grow and develop. It grows easily because it is involved in most pressing exercises, such as the bench and shoulder press as the primary mover.
What Muscles Should I Target First?
Lifters should target the muscles that they are weakest in or the ones that they are lagging in terms of development and growth. The best approach is, however, overall routine—targeting the entire body, both solid parts and those lagging.
Sometimes it is better to go back to the drawing board even after spending years in the gym. Individuals may embark on a beginner guide to training going back to the basics—alternating between compound movements and rest days. In addition, they should add isolation exercises for the muscles the compound targets. For example, on days of deadlift—they may add a stiff leg deadlift alternative such as glute bridges once the compound is completed.
When lifters have reached training plateaus that make these muscles freeze in development—they may include programs such as linear periodization—which involves de-loading the weight by 10% and continuing. This will provide a way to take advantage of periodization to supercharge your gains to overcome these plateaus to allow hypertrophy.
Alternatively, lifters can also go all out and hit the gym for 6 days straight, allowing for one day of rest by following a 6 Day Workout Routine. They may also choose to reduce training before going full out and should not be concerned about how much muscle you lose on a cut?
Including strategies such as a 4-day workout split, 5-day power building split, or progressive overload workout plan will help reduce chances of hitting training plateaus and exercising efficiently.
It should be noted that lifters should prioritize the larger muscle groups (back, quads, hamstrings, glutes, etc.) before directing their efforts to the smaller muscle groups, primarily used to stabilize these primary movers. Therefore, exercise order should be first compound or multi-joint followed by isolation or single-joint exercises to prevent fatigue that could hinder compound movements and subsequent growth.6
These extra sets, done by isolating the weak muscles that are stubborn to grow, will put the lifter on the path to eliminating the weak link in the armor. They should also ensure they are getting sound sleep to maximize gains, which will aid proper recovery as many people often wonder, is 7 hours of sleep enough to build muscle?
It’s not about the hardest muscle to grow vs the easiest muscle to grow, but it’s about correctly targeting the stubborn muscle, following efficient routines, working hard, and abiding by the full list with pics to remedy pesky muscles that will not grow.
FAQ About Hardest Muscle to Grow
Why Can’t I Build Chiseled Abs?
The primary reason abs are not chiseled or do not appear this way is due to layers of fat stored in the torso covering these abs. For chiseled abs to be visible, body fat must be between 5-9%. This should be coupled with exercises like crunches and leg raises to activate those abs to grow and get chiseled.
How Do I Grow My Calves?
The most efficient way to grow the calves other than having compound movements would be to include calf raises and single-leg calf raises to address any imbalances.
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3Medicine, N. L. (2017, May 31). Nonlinear Analysis of an Unstable Bench Press Bar Path and Muscle Activation. Retrieved 2022, from Nonlinear Analysis of an Unstable Bench Press Bar Path and Muscle Activation <https://pubmed.ncbi.nlm.nih.gov/27548799/>
4Congress, L. o. (2019, November 11). What is the strongest muscle in the human body? Retrieved 2022, from <https://www.loc.gov/everyday-mysteries/biology-and-human-anatomy/item/what-is-the-strongest-muscle-in-the-human-body/>
5Medicine, N. L. (2021, August 6). Anatomy, Shoulder and Upper Limb, Triceps Muscle. Retrieved 2022, from <https://www.ncbi.nlm.nih.gov/books/NBK536996>
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7Comstock Images. “Grimacing Man Doing Crunches.” Canva. Accessed 11 April 2023. <https://www.canva.com/photos/MAC78LoHGqo-grimacing-man-doing-crunches/>
8dotshock. Canva. Accessed 11 April 2023. <https://www.canva.com/photos/MAFCOQ8MvTw-man-doing-pull-ups-on-the-horizontal-bar/>
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