Calves are known as being the one muscle group that is most greatly influenced by genetics. They can be a stubborn muscle group to develop, especially for those who aren't genetically gifted. The deal with calves and genetics is a lot of people just don't have much natural working muscle cells to build on in the calf region. Their lower leg consists mostly of bone and tendon rather than muscle. They have a very short calf muscle and long Achilles tendon. Quite a few African Americans (and good athletes in general) fit this “high calves” curse. The long tendons give them an advantage as far as spring and reactionary strength, but a disadvantage as far as developing nice full calf development. You can increase the size of an area where you have muscle but unfortunately you can't turn tendon and bone into muscle!

Avant Research
However, anyone can increase the size of the muscles they have and a lot of people have the potential for decent calves they just don't train them properly. Many people do calf raises in a fashion that allows the Achilles tendon to do all the work rather than the calf muscles. The Achilles tendon stores elastic energy like a rubber band. It allows you to walk and run efficiently without much muscular contribution. A kangaroo can jump over a 10-foot high fence with hardly any muscular contribution at all due to the length of their Achilles tendon.

The human variant of such a feat can be found in any gym when you see lightweights repping out with the entire stack on the standing calf machine. If you perform calf raises bouncing up and down like a jackhammer you’re working your Achilles rather than your calf muscles. To actually train the calves, it's important to slow down and go through the full range of motion. Lower the weight under control. It also helps to use a pause at the bottom. Do this and you’ll likely be humbled by your poundages.

Foot and Knee Position and Calf Recruitment

Can shifting foot and knee position enable you to target different areas of the calf? Well, sort of. The calves consist of 2 muscles, the soleus and gastrocnemius. The soleus is a thin muscle that lies under the gastroc. It is much thinner, more endurance oriented, and has less growth potential than the gastroc, which consists of 2 heads and makes up the great majority of your total calf mass. Anytime you plantar flex your foot you'll recruit BOTH the soleus and both heads of the gastroc, but when performing movements with your legs straight you shift focus towards the gastroc. When performing movements with your legs bent, like you would in a seated calf raise, you shift more focus towards the soleus. Since the gastroc makes up the great majority of your total calf mass and has much more growth potential, I usually don't even recommend fooling around with targeted soleus exercises like seated calf raises unless you're an advanced bodybuilder who already has as much total calf mass as you desire and are simply looking to define what you have. Simply do all your movements with straight legs so that you get the most bang for your buck.

Toes In versus Toes Out?

There is some thought that pointing the toes in hits the outer calves and pointing the toes out hits the inner calves. Some research does suggest "toes out" activates the medial (inner head) of the gastroc to a slightly greater degree, but this is really only true when performing standing and donkey calf raise variations. Even then, you can't TOTALLY shift emphasis to inner vs. outer calves. However, since the gastroc makes up the large majority of your inner calf mass performing straight legged exercises which involve a pre-stretch will help you target the inner calves more. My favorite is donkey calf raises.

To compare the difference in inner calf recruitment with straight-legged and bent-legged variations try this: From the seated position flex your calf while placing one hand on the inner calf area and see if you can get a good contraction. Next, stand up with your leg straight and do the same thing. You should find the contraction kicks up a notch when you stand up and straighten your leg. One benefit to angling your toes slightly out is you automatically tend to place more of a pre-stretch on your calves.

Having said that, I recommend you use a stance that you're comfortable with and allows you to "feel" good contractions in your calves. You'll probably find that concentrating on getting your center of gravity over your big toe will allow you to do this. I personally find pointing the feet slightly in and really focusing on the pre-stretch and rising up on the big toe allows me to get the best overall contractions but just experiment with it and find what works best for you.