I’m currently doing a Fitness-Tip Friday mini-series where I highlight the relatively small number of muscles that have a large majority of either fast-twitch or slow-twitch muscle fibers (most muscles have a fairly even split), and therefore need to be worked accordingly in order to get the best results from your training! (Note: If you just subscribed and want to view the whole series, a catalogue of all previous FTF tips is included in the All-Access Basic Membership)
Last week we discussed how the soleus calf muscle has the HIGHEST percentage of Type I “slow-twitch” muscle fibers of any muscle in the body, and how to train it accordingly. Well, one of the most interesting dichotomies of the body is that the OTHER primary calf muscle – the GASTROCNEMIUS (aka “gastroc”) – has one of the highest percentages of Type II “FAST-twitch” muscle fibers in the body!!
This is one of the biggest reasons why so many people have a hard time building their calves!! They mistakenly train both the soleus and the gastroc the same way, with the same weight loads, rep counts, tempos, etc. (and then blame the lack of results on “genetics”). When if you really want to see growth, you have to work them COMPLETELY differently! (In reality, studies show that genetics only account for about 20% of baseline calf size.)
The gastrocnemius lies on the surface just below the skin and has MEDIAL (“inner”) and LATERAL (“outer”) heads, which create that “V” shape. So while the soleus provides much of the volume… the gastroc provides additional volume AND all of the definition!
ALSO…
Because the gastroc is BIARTICULAR (it crosses two joints – the knee and the ankle), it follows a REGIONAL HYPERTROPHY pattern that ALL biarticular muscles have. Which is that the muscle region closest to a joint gets activated the most when that joint is worked.
Thus working the gastroc at the KNEE will shift more of the load towards the UPPER gastroc regions… while working it at the ANKLE will shift more of the load towards the LOWER gastroc regions. (See image above)
Of course, there is no hard line dividing the upper & lower regions, and there are many other regional hypertrophy factors that can influence what sections of the gastroc are activated and to what degree. However, this biarticular effect is a good rule of thumb!
So you need to work it via BOTH straight-knee calf raises and straight-hip, dorsiflexed leg curls! (Not training the gastroc at both ends is another reason why so many people have a hard time building their calves!)
1) STRAIGHT-KNEE PLANTAR FLEXION
The plantar flexion (aka calf raise motion – click to view) should be performed with your KNEES STRAIGHT to preferentially engage the gastrocnemius… and you should alternate between working it with your foot NEUTRAL (toes straight forward), INTERNALLY-ROTATED (toes-in), and EXTERNALLY-ROTATED (toes-out). (You can refer back to the FTF Tip from Week 25 for details on the rotations and what they each work.)
And then since the gastroc is a fast-twitch dominant muscle, you need to perform the calf raises with one or both of the following:
1. HEAVY WEIGHT (≥80% 1RM)
2. QUICK, EXPLOSIVE CONTRACTIONS
A great way to work the fast-twitch gastroc fibers is to Jump Rope while keeping your knees as straight as you can, so that gastroc has to generate ALL of the explosivity to lift your body off the ground! (If you haven’t done this before, it’s MUCH harder than it looks and will leave your calves sore for DAYS!)
2) STRAIGHT-HIP, DORSIFLEXED KNEE FLEXION
The leg curls should be performed with your HIPS STRAIGHT (like they are on a prone leg curl machine -NOT a sitting leg curl machine) because that will put your hamstrings into active insufficiency, maximizing the load on the gastroc!
Your ankles should also be DORSIFLEXED (aka ankle bent upwards – click to view movement) because that will AVOID putting the gastroc into active insufficiency as well, ensuring that it can exert full force throughout the entire leg curl range of motion!
And then once again since the gastroc is a fast-twitch dominant muscle, you need to perform those leg curls with one or both of the following:
1. HEAVY WEIGHT (≥80% 1RM)
2. QUICK, EXPLOSIVE CONTRACTIONS
You don’t need to use both heavy weight and quick contractions at the same time (particularly if you’re at high risk for injury). but it is important to work both into your routines. As always, variety is key!!
Application: Make sure to work your gastrocnemius from BOTH ENDS, and do so with HEAVY weight and/or QUICK contractions!!
Relevant Research Article(s):
1) Novel Insights Into Biarticular Muscle Actions Gained From High-Density Electromyogram
2) Resistance exercise elicits fiber type-specific changes
Related Dr. Gains YouTube Video(s):
1) EVERYTHING you NEED for BIGGER, HEALTHIER, & MORE DEFINED CALVES (Gastrocnemius) In 2 MINUTES! [2MM]
2) The Soleus Secret (The Anatomy behind Calf Definition and Volume)
Dr. Gains 
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