Study the bodybuilding routines of the champions, both classic and modern, and you’ll notice these principles somewhere applied:
- a diversity of compound and isolation exercises
- mostly moderate rep ranges
- full ranges of motion
- continuous tension for the working muscles
- at least three exercises per muscle region
This wisdom developed through trial and error within bodybuilding can now be explained beyond just seeking out variety.
A diversity of exercises is required for active and passive tension for each muscle.
Active tension, developed when overloading a muscle slowly and through maximum effort, and passive tension achieved via long muscle lengths, are both important.
Internal moment arms that differ for sub-regions within a muscle, along with neural activation patterns that change by function, appear to show that variety achieved through different movements, angles, and strength curves is optimal for muscle growth.
Nonetheless, implementing variety is hardly an exact science yet.
A moderate rep range maximizes the number of reps for high-threshold motor unit recruitment, addressing the fast-twitch muscle fibers with the most growth potential.
Though still speculative, a moderate-to-high number of reps allow time fighting through the burn generated by hydrogen ions, inorganic phosphate, and lactate that may stimulate energetic growth or sarcoplasmic hypertrophy from metabolic stress during anaerobic glycolysis.
At the least, we can overload fast-twitch muscle fibers through both metabolic stress and mechanical tension, perhaps helping with recovery versus applying either alone.
Continuous tension further increases metabolic stress, which likely either potentiates or separately operates alongside reps near or at failure, for myofibrillar hypertrophy, to grow muscle.
A full range of motion involves a stretch that stimulates longitudinal muscle growth or additional sarcomeres in-series. This is an adaptation to handle eccentric exercise, shifting the optimal length of the muscle to a longer overall length.
Sarcomeres, the basic contractile units of a muscle fiber, also vary greatly in length and therefore have different optimal lengths to stretch and contract throughout a range of motion.
Finally, we have the bodybuilding wisdom of using at least three exercises per muscle region, which involves many of the reasons just mentioned.
Active Tension, Passive Tension, & Internal Moment Arms
We know that both active tension and passive tension stimulate muscle growth cross-sectionally or longitudinally.
With three exercises per region, we address both these factors for all of the muscles involved:
- One exercise for active tension throughout the whole region.
- One exercise for passive tension of the multi-joint muscles.
- One exercise for passive tension of the single-joint muscles.
Active tension is maximized when the muscle is at or near a medium length. Think basic exercises like bench presses, squats, pull-ups, curls, and arm extensions.
These exercises, done properly, allow constant tension near an optimal length through a parabolic or bell-shaped strength curve that feels heaviest at the midpoint.
Passive tension occurs at long muscle lengths. This increases sarcomeres in-series, especially developing the areas near the myotendinous junctions, or the distal and proximal ends of the muscle, building fuller muscles.
Though research shows a drastic increase in fiber length for chronically-stretched muscle, which is not practical, it also shows an increase by including an eccentric or lowering phase at long muscle lengths as well.
I also believe this may stimulate hyperplasia, or entirely new muscle fibers via fiber splitting from active overstretch, if applied consistently. Increased stiffness from passive tension also encourages ECM growth via mostly collagen.
Increasing passive tension means ascending strength curves to overload the most stretched positions. Think pull-overs, dumbbell flyes, and arm extensions with the elbows flared out at the top.
The deepest stretch occurs only for a single muscle group per exercise, so we require two exercises per region to achieve this goal.
Use a controlled and deep lowering phase for the rep. It is important to note that the highest passive tension occurs during active overstretch, when active tension is generated simultaneously, hence why stretching by itself fails to do much.
Finally, we need enough work performed for the target muscle. The internal moment arm represents the mechanical advantage of a muscle acting on the joint. A larger moment arm means this muscle will do more work relative to others involved, establishing the prime mover for an exercise.
A muscle at a strong length can still have a poor mechanical advantage and will therefore play a lesser role. A muscle can also dominate despite functioning at a shorter, weak length. It needs to generate more torque than other muscles involved, otherwise other muscles fail first.
The moment arm complicates things in some cases. For example, even though supination, or using an underhand grip, on the curl will shorten the biceps, it will improve the moment arm. The solution is to use an incline curl, while supinating during the movement, to emphasize the biceps yet still work them at a strong length.
Pectoralis Major (Sternal)
Pectoralis Major (Clavicular)
- Flat Dumbbell Press = 3×6-12
- Flat Dumbbell Fly = 3×6-12
- Dip (Wide) or Decline Dumbbell Fly = 3×6-12
The sternal or lower portion of the chest can
extend the shoulder, while the clavicular or upper portion can flex the shoulder.
With dumbbells, you can more easily choose a midpoint between these two actions, with the other functions of internal rotation, horizontal flexion, and adduction shared.
So by using a neutral grip and descending as low as possible on the flat dumbbell fly, you stretch both heads.
The pec minor that lies below the chest, yet still contributes to the overall size and a flatter chest, depresses the scapula. The elevation of the shoulder blades at the bottom is required to stretch it fully, only possible with a dip or a decline bench.
The flat press maximizes active tension for all the muscles involved.
Biceps Brachii (Long & Short Heads)
- Incline Dumbbell Curl = 3×6-12
- Preacher Hammer Curl = 3×6-12
- Supine Curl = 3×6-12
Turning the wrist so that the palm faces upward, or supination, improves the internal moment arm for the biceps. An incline dumbbell curl generates active tension for the biceps and brachialis at strong medium lengths, while limiting the brachioradialis from dominating the movement.
(Though a flexor of the arm, I consider the brachioradialis a forearm muscle better stretched and worked alongside the wrist flexors and extensors, through a reverse curl for passive tension and possibly a hammer curl for active tension.)
The preacher hammer curl allows hyperextension of the elbows at the bottom of the movement, increasing passive tension for the brachialis.
The supine curl, done while on a high flat bench, develops a maximum stretch in the biceps.
Gastrocnemius (Medial & Lateral Heads)
- Heel Raise (Slightly Bent) = 3×8-12
- Heel Raise (Straight) = 3×6-10
- Heel Raise (Bent) = 3×6-10
Straight knees stretch the gastrocnemius.
Bent knees stretch the soleus.
Slightly bent knees allow the whole triceps surae to exert high active tension at medium lengths.
Some also prefer a higher rep count on muscle groups like the calves and forearms, ostensibly since they have a higher proportion of slow-twitch fibers. I’m unsure if this works. Nonetheless, the concept is popular within bodybuilding circles.
With these exercises, you thoroughly hit all the muscles within a region. Changing exercise order will emphasize the goals for earlier exercises. You can also modify the exercises to focus on a muscle head.
For the chest, you could use a slight incline with the bench to extend the shoulder, which emphasizes the upper clavicular portion, reducing the stimulus for the lower sternal chest.
For biceps, the long outer head is stretched when the elbows are close to the sides, with the arm adducted and the shoulder extended.
The short inner head is emphasized when the elbows are out, with the arm abducted and the shoulder also extended.
You could use this knowledge to stretch out one head more or less, such as an incline curl with the arms elbows pinched or a high cable curl, respectively.
Toes out on heel raises will evert the foot, which stretches the medial or inner head of the gastrocnemius.
Toes in on heel raises will invert the foot to stretch the lateral or outer head of the gastrocnemius.
Finally, it is worth saying that many bodybuilders will not stretch the deeper single-joint muscles, such as the pec minor and brachialis. They instead choose an exercise that…
- works the target muscle in a more shortened state, such as a cable cross-over for the pec major or a concentration curl for the biceps.
- isolates each head individually for either active or passive tension, such as an incline press and/or fly or a flat press and/or fly.
Within the 2nd option, you may be able to more easily get a deep stretch due to better leverage. Elongating the muscle through all of its functions, instead of greatly through fewer, may allow the greatest possible stretch for a muscle head. Some heads also are tricky to overload at the same time, requiring perfect positioning, such as for the outer and inner biceps or the upper and lower chest.
Ultimately, it may be sensible to rotate among the three options, as there probably are no bad exercises, only more or less effective ones.
The Bodybuilding Wisdom of Three Exercises Per Muscle Region
Working backwards from the components that comprise muscle, these variables could develop the following growth components:
- Overload: concentric/eccentric phase done slowly, highest at medium lengths
- myofibrils in-parallel/cross-sectional myofibrillar hypertrophy
- conducive to metabolic stress
- hyperplasia from active overstretch?
- Overstretch: eccentric phase at long muscle lengths
- sarcomeres in-series/longitudinal myofibrillar hypertrophy
- connective tissue growth
- hyperplasia from active overstretch?
- Lower reps (<10), failure-based training, & longer rest periods (mechanical tension):
- myofibrillar growth, especially fast-twitch?
- connective tissue growth
- bone growth, mostly density (heavy weight only)
- Higher reps (>10), constant tension, & shorter rest periods (metabolic stress):
- sarcoplasmic hypertrophy
- myofibrillar hypertrophy, when taken near to or at failure (could this be compromised with longer set durations?)
- possibly slow-twitch fiber growth?
- additional glycogen/water storage
- mitochondrial biogenesis?
- Volume (more sets): acts as a multiplier for all factors but requiring neither too much nor too little (fitness vs. fatigue)
3 exercises per muscle region allows for these variables to be addressed without too much work.
Nonetheless, I’m unsure if slow-twitch fibers can be emphasized, probably growing as fast-twitch fibers do in response to tension. Mitochondria also seem to increase the most with endurance training, so as they proliferate would decrease fiber size to facilitate oxidative metabolism.
3-4 sets of 3 exercises allows 9-12 sets for a muscle region weekly. This number of sets appears optimal for muscle-building, especially if all the sets are taken to or near failure. Another day with fewer sets for each session, or splitting up the exercises for more sets, could increase overall volume if needed.
Three exercises also promote a variety of movement patterns to address sub-regions within a muscle or even muscles that are usually ignored entirely.
To give an example, the dumbbell fly stretches the subscapularis, and a wide grip pull-up, with more shoulder adduction than extension, works it through active tension.
Developing the subscapularis, a muscle typically ignored but taken care of through variety, fills in the chest alongside the pec minor.
Consider three exercises per muscle region. You will develop both active and passive tension within all the muscles. Modify these three exercises as needed depending on your goals.
With a moderate rep range for both mechanical tension and metabolic stress, plus a few sets each done weekly, you should have a bodybuilding program that develops all the components for larger muscles.