What’s the importance of being mobile?
Simply put, being mobile gives you a larger margin of error when moving to both reduce your chance of injury while improving your sport performance – especially in a sport like tennis.
Let’s look at two terms that are important in understanding how mobility works – eccentric and concentric muscle positions.
In general terms:
Eccentric = lengthened muscles, expansion, force absorption
Concentric = shortened muscles, compression, or force production
I like to use a rubber band as an example of these muscle actions.
If you stretch a rubber band this would be considered an eccentric orientation and if you let go of the rubber band then this would be considered a concentric orientation.
Now, if you want the rubber band to shoot across the room, you must pull it back further to shoot it further – this is the importance of having full mobility of a muscle.
If muscles have a difficult time “expanding” or absorbing forces during athletic movements then the pressure is usually placed onto tendons or joints and this is where injuries can happen such as tendonitis.
Of course, you can have too much eccentric orientation and become too “loose” and have a difficult time producing force and performing well.
This is why strength training and training these motions are very important!
How does expansion and compression fit into athletic performance?
Let’s take a look at the 3 phases of hitting a tennis ball where we can see these muscle actions at work.
Phase 1: Preparation Phase or Wind-up
This is at the beginning of your tennis stroke when you bring your racquet back to prepare your stroke.
This is primarily an eccentric or expansive action of the muscles. The muscles must lengthen to get you back into your stroke preparation.
Phase 2: Acceleration and Ball Contact
This is where you make contact with the ball.
The strike zone is primarily a concentric or compressive action of the muscles. You must create force and compression in the muscles to create speed and power.
Phase 3: Follow-through
End of your tennis stroke where you are following through on hitting the ball.
This is primarily an eccentric or expansive phase because now you must have the muscles that just contracted lengthen out to prepare you for your next movement.
The idea of expansion and compression can also be expanded upon if we think about breathing.
When we breath in (inhale) we expand our body to bring air in and when we breath out (exhale) we compress our body to get the air out.
Now, create a mental video of when you breath during your tennis stroke.
When executing a swing, athletes will audibly exhale forcefully. Its hard to imagine them audibly inhaling instead as they hit the ball, and now we better understand why.
Exhaling creates compression and thus improves force!
So in summary, by having the ability to lengthen and shorten muscles well, we can improve our joint and soft tissue health as well as our performance on the court!
This is why having a proper training program before and after an injury is so important!