The vertical jump is a combination of knee extension, hip extension, and ankle extension. We place a LOT of emphasis on strengthening the knee extensors (quads) and hip extensors (glutes), but what about the calves? Shouldn't we strengthen them just as much for the same reasons?
The answer to that is YES we should, at least to a certain degree, but here's the deal: Any activity you perform on your feet can strengthen your calves to a degree. If you perform a lot of high intensity plyometrics your calves can get VERY STRONG from that alone. In fact, some coaches like Charlie Francis didn't advocate any calf work with athletes because the thought was sprinters get enough of it from all the sprints and jumps they do. Excessive calf hypertrophy can also add excessive weight (in people prone to growing large calves), which can negate optimal movement efficiency. The calves contract thru a fuller range of motion during normal activity than the other prime vertical jump muscles (glutes and quads). Just going out and performing 30 seconds of jump rope, sprints, or an assortment of various plyo drills is enough to give most people a significant calf pump. Where do you think that pump comes from? Muscular activity!
Additionally, in the past many vertical jump programs and gimmicks focused solely on the calves to the extent that all the other more important muscles were neglected. From 1990 thru 2005 the majority of vertical jump routines and gimmicks were platform shoes, jumpsoles, and extremely high volume plyometrics. These routines were all calf/ankle dominant, and most of them weren't all that effective.
Having said all that, a degree of general strength in the calves is valuable and important and many people can benefit from it. MOST of your improvements are going to come about from increased hip and knee extensor strength and power, but proper ankle extensor training can often give an individual another few inches vert increase. The key is to train the calves as a SUPPLEMENT to everything else. Typically, the calves might contribute 15 to 25% to most style of jumps, more or less depending on the individual. Additionally, having strong and powerful ankle extensors enables you to absorb force efficiently so you can thereby leverage more of your hip and knee extensor power into the ground.
The last several years I've also noticed a general shift away from overdoing movement work. People and coaches are a lot more cognizant of proper training methodology now than they were 6 or 7 years ago. People place more importance on recovery, more importance on general strength activity, and less importance on overblowing sports specific work. That's generally a good thing, but I've noticed in many athletes a general weakenening of ankle extensor power as a result. Movements like plyometrics may be high tension, but they don't have the duration of tension that builds good baseline strength. Strengthening your calves with weights can help stiffen up your ankles and in this sense being "stiff" is a good thing. My opinion is an athlete should strive for enough baseline calf strength to perform 20 controlled reps of barbell calf raises or exercise equivalent with around 1.5 x their bodyweight. It shouldn't take much volume to achieve that, and in my opinion calves don't need to be worked with weights year around. A few sets of 15-25 reps on a calf raise (or equivalent) twice a week in a strength phase should be enough to give most the baseline calf strength they need.
The calves consist of the gastrocnemius and soleus:
You hit the gastroc anytime you perform ankle extensor variations with mostly straight legs, such as a standing calf raise or donkey calf raise. You hit mostly soleus anytime you perform variations with your knees mostly bent, such as seated calf raises. Which one should you focus on? Well, the gastroc is about 70% fast twitch and the soleus is about 70% slow twitch. The gastroc is most active when you blast off the floor. Therefore I'd focus on mostly straight leg variations: barbell calf raises, donkey calf raises, standing calf machine, or single leg calf raises.
Barbell calf raise:
Single leg calf raise:
Here are a few more tips for training the ankle extensors:
A: The Calves are often TOUGH: Since the calves get utilized a ton during daily activity they can handle quite a bit of frequency. It's possible to train them every day with little in the way of ill effects. In my experience an alternating frequency approach works really well. Try alternating your frequency 3 times one week, twice the next, 3 times the next, twice the next.
B: Don't bounce!: When performing calf raises it's possible to get a substantial boost using the bounding action of the achilles tendon. There are plenty of skinny guys who can rep the stack bouncing the weight up and down. To focus on the muscle try not to bounce out of the bottom of a calf raise.
C: Account for the shorter range of motion: The range of motion of a calf raise is so short they require either higher reps or intentionally slower tempos to get the same time under tension as most typical movements. For example, a heavy set of 5 squats performed at a normal tempo might take 25 seconds to complete. Most people will complete a heavy set of 5 calf raises in 10 seconds or less. Therefore it's essential you either increase the reps per set or slow the movement down. I consider a set of 25 calf raises approximateley equivalent to a set of 8 squats as far as the qualities effected. If you want to utilize lower reps try using a 5 seconds eccentric (lowering phase). One workout I like is 5 sets of 5 reps with a 5 second lowering phase, 1 second pause, and explosive concentric.
D: Stretch daily: I'm not the first trainer to make the observation that good flexibility in the calves often equates to jumping success. Not only does increasing their flexibility increase your movement efficiency, but a recent study verified that daily stretching of the calves also helped slightly with strength increases. Therefore, if you’re interested in improving your vert, I recommend you stretch your calves daily for at least 20-30 seconds. Stretching them multiple times a day is even better.
Good calf stretch:
E: Phase calf training in and out: If you're engaged in a lot of running or jumping, back off on the calf work. Once you build a base of strength in them that strength is easy to maintain via normal movement. One volleyball trainer I trained was addicted to training his calves. He did get results from it but continued trying to train them during his season when he was playing 3 or 4 hours several nights per week. He backed off his calf work and his vert shot up a couple of inches from that. Because they get quite a bit of stimulation from your movement work the calves need not be trained year around with loads.
You can see plenty of examples of how to implement baseline ankle extensor training throughout the workouts in the Vertical Jump Bible 2.0: