Keep your elbow in

I was playing tennis this morning and had to keep reminding myself of this useful chestnut on every serve. I jacked my shoulder playing doubles (badly) on Monday and haven't recovered. (Actually, I first jacked my shoulder when I was 16 or so and have been exacerbating the injury ever since with my crappy mechanics.) As I was quietly repeating this mantra, I thought how useful this advice is in so many contexts.

• Tennis. Well, this is obvious. You need to whip that arm forward, and to do so effectively and with minimal damage, the elbow must come in before the wrist.
• Baseball. In terms of throwing, it's the same motion as a serve, so the same basic mechanics apply. Hitting, well, you don't want those elbows flapping in the breeze or there'll be no snap.
• Golf. You try swinging a club with your arms akimbo. Trust me, I suck much more at golf than you do, and it doesn't help.
  
• Rollercoasters. Not quite as essential on most rides, but you really don't want those arms hanging out too far.
• Sex. Actually, I'm not sure it's important to keep the elbows in, but I'm going to pay more attention in the future. I suspect there's an incremental efficiency increase to be had there as well.
• Basketball. Unless you want to shoot like Gerald Wallace, keep your elbow in.