Thursday, May 17, 2012

The Nature of the Rose: Explosive Players and Injuries

In another article I looked at which types of players had long careers and were able to play effectively into their late 30's. While total career minutes is an important factor, undoubtedly player type cannot be ignored. It's reasonable that athletic slashers have shorter careers than outside shooters, but it's unclear how true this is. What exactly causes these injuries?

One mechanism of stress on the body is torque, which occurs from twisting or rotating. Most of the mainstream media conflate torque with power. Strictly speaking, it's the tendency for an object to rotate about a central point, or pivot, when a force is applied perpendicular to said point. It's why doors swing open and closed and why wrenches are so effective. The reason for the confusion between power and torque is that typical vehicles are gas or diesel powered; the torque is caused by the engine. In a car the torque is the turning force from the engine, and the actual power you get depends on the torque and RPM (as well as some efficiency losses converting that to the wheels.)

This doughnut has undergone extreme torsion (Flickr)
What torque can cause is torsion, which is a kind of stress caused by rotation. Think of a tower being twisted not by bending but staying within its axis and turning -- the twisting causes stress, and the greatest stress occurs at the furthest point from the center of rotation. Ultimately all that matters though is the shearing force, which is force in opposite and parallel directions, that's made through various processes like torsion and compression.

That's enough about of that talk. What's it have to do with NBA players?

Recently the ACL injury to Derrick Rose has completely changed the playoff picture and marred the career of a bright young star. He has been struggling with injuries all year, and people naturally try to find the cause of both his season and the torn ACL. What doesn't cause those particular injuries are a heavy toll from minutes or, well, actually no one knows why it happens. The best athletes and the ones in shape seem to be the most susceptible. However, the tear itself usually occurs when the hips are rotated at the wrong time, and this causes torsion in the weakest section of the lower body: the knees. Planting your foot wrong is also a culprit as it puts your body in the wrong position, and any eccentricities in the body's alignment at high speed with these athletes can cause huge amounts of stress.

The players most susceptible to those injuries are the ones constantly cutting, side-stepping and zig-zagging a path to the rim; hesitation moves and quick stops can also do it. Driving straight at the rim, jumping normally with good balance and landing in the same trajectory doesn't cause the same problems. Rose is known for his explosive moves to the rim and avoiding the defense mid-air. On the particular play where his team's title chances vanished Rose took a big hop to his right, planted somewhat awkwardly and upon jumping again one could see his pain. That kind of dynamic motion at high speed leads to an ACL tear.

With the nature of the injury occurring like a dramatic twist in a movie, random and landscape changing, who the next victim will be is the obvious question. The player would be one who generates a high amount of torsion in the knee from twisting and turning, which usually happens on drives to the basket. The obvious stars who come to mind are Ginobili and Wade, and both are known for dealing with injuries constantly. Ginobili helped bring the Euro-step to America, and even in his mid-30's he's constantly changing directions with each step, putting high amounts of stress in not just his knees but his whole body. The famed Phoenix medical staff realizes that an injury in one location affects the whole body, and likewise Ginobili has had to suffer through multiple ailments everywhere. Wade darts and dodges as well but with even more power. One of his most famous moves is his dunk over Varejao, who falls over like a folding table, when Wade plants on one leg but switches directions and goes straight up to the rim. Other similar guys include Brandon Roy, known for his stutter steps and quick stops, and Chris Paul, who can still use his speed after knee injuries to dart around the defense.

Russell Westbrook is one who's inextricably linked to Rose because they're both young, athletic point guards who can score, but he's not as likely to suffer an ACL catastrophe. He's a straight-line driver, one who uses his speed to run directly to the rim. He's also never missed a basketball game since junior high, reportedly. Another man of steel is LeBron James, who uses his size, strength and speed to finish over opponents rather than cutting and dodging. Like Westbrook, he's also never undergone a serious injury. Vince Carter has been playing surprisingly well at an older age, but he's also one to make a beeline to the basket rather than side-stepping around. He does jump over the defense, but if you do so without putting torsion on your knees from twisting your body you can escape numerous injuries, unless you want to fake a few. There have been many comparisons to Ginobili, but James Homeless Beard Harden uses more straight-line drives. I would, however, take mental notes watching him, seeing how much he does zig-zag and how it affects his lower body.

Injuries are an area still mysterious to the NBA, and even something like total minutes in the season or career is not an accurate predictor of collapse. Derrick Rose won an MVP, got to the conference finals and then he followed it with an injury-plagued season ... and suffered an ACL injury that will likely prevent him from playing next season. One can't make too many logical leaps from just one incident, but it's important to figure out why these things happen. After all, an injured player is of no use, as all they do is it on the sidelines in nice suits like they're watching their own funeral.

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