There’s a lot that goes into athletic movement, but the basic idea is pretty simple – the more muscle you can recruit to help you move and balance, the more athletic you’re going to be. Additionally, the stronger your muscles, tendons, and ligaments are, relative to your weight, the more athletic you’re going to be.
One of the simplest ways to maximize your muscle recruitment on court is to move with triple flexion. Flexion is an anatomical term that just means “decreasing the angle.” A common place you’ll see it is in the sentence:
Wrist flexion occurs during the forehand follow-through.
In other words, during the follow-through, the hand bends towards the forearm – the wrist angle decreases.
What to Bend
To move athletically, we want flexion of the:
When the hips are bent, the posterior chain is primed. The lower back, glutes, and hamstrings are ready to fire to forcefully straighten out that hip angle, which can drive the body forward, up, left, right, or even backwards, depending on the exact situation.
When the knees are bent, the quadriceps are primed, ready to fire and straighten out the knee angle, similarly driving the body.
When the ankles are bent past their typical 90 degrees, the calves are primed. The calves act as springs when the athlete lands with a midfoot or forefoot strike: upon landing, the ankle angle shrinks, the calves store elastic energy, and then they contract and release that energy, driving the foot back off the ground.
Hip flexion is something that’s often missing in a player who is sedentary for most of their life. In the sitting position, the glutes, hamstrings, and lower back are very relaxed, and as a result, many players have no athletic awareness of how to recruit these muscles.
If an athlete isn’t used to firing these muscles, it’s likely they will play with only minimal hip flexion. The bent hips position is what allows these muscles to drive the body, so if a person’s brain doesn’t think the glutes and hamstrings are worth using, they won’t adopt a bent hips position.
Verbally cuing a player into a bent hips position will often immediately improve their movement, but not always. For a player who really struggles to fire these muscles, the low bar squat and the deadlift, performed properly, are great proprioceptive training tools to remedy the issue.
Knee and Ankle Flexion
A small amount of knee flexion is always healthy. It promotes quadriceps usage as you drive off the ground, and it creates another degree of freedom for your body to use when absorbing the shock of landing.
The farther the knees go out over the toes, the more knee flexion and ankle flexion we get. You might be wondering here – isn’t an excessive knees-over-toes position what we said to avoid in order to protect your knees?
Yes and no. The knees-over-toes position is an extremely useful athletic position, and you want to be able to utilize it, but it’s also a high stress position for your knees.
The biggest knee killer is routine knee flexion without accompanying hip flexion. If the knees are bent, but the hips are straight, then the knees and quadriceps must accommodate the entire load of the body, without help from the strong muscles of the lower back, glutes, and hips.
This position should only be used when necessary. In Roger’s initial drive to the overhead, his hips are bent: his glutes and hamstrings are playing a large roll in driving his body forward, not just his quadriceps. It is only when playing the overhead itself that he straightens out his hip angle, and uses an almost exclusively quadriceps driven motion.
Knee flexion with hip flexion is what maximizes force production and safety, but to maximize athleticism – your ability to do anything and everything around the court – your knees need to be strong enough to occasionally handle things all on their own.
Learn Your Own Knee Ability
Everyone’s knees can handle different amounts of stress without becoming injured. The stronger your knees, the more knee flexion you can use, and the more athletic you’ll be. The weaker your knees, the less knee flexion you can use, and the less athletic you’ll be.
Roger Federer possesses world class knee strength. Here’s his victory celebration from Wimbledon 2004. Not only did he get his knees into this position, but he fell into this position and then caught himself here. Chances are, if you tried this, your knees would snap.
That’s why Roger Federer can, as a matter of routine, enter positions with his knees way out over his toes, drive out of those positions, and not get hurt. He has world class knees.
If you don’t, you need to rely more on your butt and hamstrings, and less on your knees. Sit your butt back more, bend over more at the hips (with a straight back), and use less ankle flexion.
Posterior chain training will make you more athletic. Knee training will make you more athletic. Stronger calves will make you more athletic. Movement improvement is a dance between training and technique.
The goal of training is to enable yourself to enter more athletic positions without getting hurt, and then to empower yourself to generate more force out of those positions.
This article is an introduction to the basic biomechanics of athletic movement, but I’d be remiss if I didn’t include some brief training recommendations as well. Most adult players only have a few hours per week to train (if that), so these are the densest ways to use that time.
Hip flexion and glute/hamstring strength
The lowbar squat to parallel, and the deadlift. These two exercises are the best for not only increasing the strength of these muscles, but also your proprioceptive awareness of how to fire them. Focus on high quality, full range of motion reps, during which you can feel the proper muscles firing and fatiguing. Lift heavy, but not so heavy that your form is compromised.
Knee ability and quadriceps recruitment
Loaded backwards running and the ass-to-grass squat. A very common injury case for the knee is deceleration – the knee has to slow you down when you stop, and it takes a lot of load when doing so. Decelerating forwards is a very similar job to accelerating backwards, which is why loaded backwards movement strengthens the knees.
The ass-to-grass squat is similar to the squat to parallel, except that proportionally more of the load is on the knees – the knees-over-toes position is loaded, as is the entire range of motion into and out of it.
Ankle ability, foot striking, and calf strength
Barefoot running. It’s the activity your foot was designed for, and it’s the fastest way to train it back into shape. If you’re used to running with shoes, your natural foot ability is probably very low, and you’ll have to start very slowly with this at first – not even a full mile on your first run. Ease into it, don’t ignore pain.
Running barefoot will activate and train the entire arch/ankle/Achilles tendon/calf spring that was built into your foot so your ancestors could run their prey to death, and that training will carry over into your tennis foot striking as well.