Hip mobility and shoulder injuries: Implications for tennis, volleyball and baseball players.

In overhead sports such as tennis, beach volleyball and baseball, shoulder injuries are an occupational hazard. We all watch in awe when Milos Raonic repeatedly sends down lasers well over 200 Km/H, or when Justin Verlander lights up the radar gun by freezing hitters with 100mph fastballs in the 8th and 9th inning. It’s mind blowing watching the best beach volleyball players launch themselves in the air and unleash cannons in excess of 85mph. The ability to do these things largely comes from an ability to generate velocity through the shoulders of these athletes, but over the course of a season, and career, this takes its toll on the supports structures of the shoulder and injury becomes almost inevitable.

As therapists/coaches/trainers, we’re all interested in one thing-the well being of our athlete, and a well athlete is able to play, and if they are playing they are able to do the things mentioned above, but they can’t do them from the sideline.

We know that in order to keep them safe and performing well, they need strength and timing of not just the rotator cuff, but of the scapula stabilisers.

We know that thoracic mobility is important to their shoulders, and that problems in the cervical spine can affect peripheral nerves to the arm.

But what about their hips?

More specifically, what about their non-dominant hip?

Justin Verlander, Milos Raonic and Ben Saxton all need great control of their shoulder stabilisers (above left) but what about their hips?

A study in 2010 titled Passiver range of motion of the hips and their relationship with pitching biomechanics and ball velocity in professional baseball pitchers by Andrew Robb, Glenn Fleisig and Kevin Wilk et. al. also wondered about the hips and their impact on the shoulder.

They found:

• that for all directions measured (IR, ER, Abd, Add) the non-dominant hip had reduced PROM (It was an acknowledged flaw of the study that they didn’t measure flexion and extension)
• Although individual hip range (for rotation) didn’t correlate with ball velocity, the total arc of rotation did correlate. Meaning that a reduced total IR+ER for the non-dominant hip lead to reduced ball velocity in the pitchers tested
• Total arc of abduction + adduction in the dominant hip also had a positive correlation with trunk separation velocity. This initiates the forward momentum of the pitch, affects stride length and therefore (presumably) an increase in this range of motion will increase kinetic energy production and ultimately greater ball and angular velocity.

So what does this all mean?

For me the, the main takeaways from an injury management or prevention perspective are:

• Throwing/serving are complex skills that when done well, use the summation of forces idea to generate a whip like motion, that travels up from the ground, through the body and out the hand to either let go of the ball (baseball) or hit it (tennis/volleyball).
• If an athlete (tennis, volleyball or baseball) begins to lose rotational ROM in their non-dominant hip, their velocity of shot is going to go down because they aren’t able to maintain all the rotational torque they have generated because they will “hit a wall”-imagine throwing across your body. To try and regain this lost velocity the athlete will swing/throw “harder” with their arm, or shoulder. This will lead to increased strain on the stabilisers of the shoulder, and as mentioned in the beginning, increase the risk of injury to this part of the body.
• Hip motion is like Gleno-humeral Internal Rotation Deficit (GIRD) of the shoulder-because of the unilateral nature of most overhead sports, there will be a deficit between sides. However, it is important to make sure that the deficit doesn’t change.

NB: At the moment I am unaware of any data that has found optimal range of motion for an overhead athlete at the hip.

• Yes tennis and volleyball have different demands to baseball, but the principles are the same.
• Tennis is more bilateral than baseball due to the use of the backhand stroke, but the majority of time is still spent on one side (serve and forehand). Therefore when treating/training a tennis player and focusing on their shoulder, it is imperative to address their hips (especially non-dominant) and monitor mobility in this area.
• Volleyball’s differences lie in the fact that they generate their overhead force in mid air, and thus don’t have ground reaction forces to help as they do in baseball.
• Once again, movement is the key; a great therapist/trainer works with the sports coach, not against them.
• As I mentioned in the first take away point, these are complex skills and difficult to do well. If they were easy I would be preparing for an opening day start with the Jays, not writing this article.
• Be aware of the influence of hip mobility on shoulder biomechanics, explain it to the athlete, but work with the coach to ensure it is being used properly.
• It doesn’t matter if I give an athlete all the passive hip range of motion in the world, if they can’t convert that into their throw/serve/spike and they go out on the field and just “hit” with their arm, they will still get injured/not perform as well as they might.
• The Robb et al, article also mentioned that for pitchers, to much non-dominant ROM can be bad too. If the athlete is now opening up their pelvis and trunk too early, they prematurely initiate the cocking phase, thus losing some of the kinetic energy from the lower extremity-therefore decreasing velocity again. So we, as service providers must make sure to work with the skills coaches to get the best result for our athletes.

Next week will look at other injuries of the pelvic area and the implications associated with these injuries…… but for now have a look at Aroldis Chapman and see what happens when everything goes right.