Just think, you can repetitive stress injuries in your office. If using a mouse wrong can hurt your wrist, think how much bad it could be on your bike if you misaligned. Here are some products to help reduce the chance of getting hurt from just riding your bike.
On-One Mary Bar
Who ever came up with the standard flat or riser mountain bar never looked at how the hands actually sit. Traditional bars put the wrists near the limit of their range of motion making over use injuries much more likely. If you experience wrist pain when riding your mountain bike come in and check out the Mary Bar. I got them in to help my wrist problems and figured I can't be the only one who gets sore wrists.
Multiple hand positions and increased back sweep make for a more ergonomic hand position. I've been riding them for a few months now and it really improves comfort and bike handling. By moving your hand in and out on the grips you can fine tune your weight distribution for climbing. As well, out of the saddle you'll find you have more leverage as the elbows stay tighter to the body kicking in the stronger upper back muscles. I think it adds a hardcore look to my bike as well. There are other options in this style of bar including the Misfit FU Bar and Soma Clarence bar.
Comfort comes down to contact points. Butt, feet and hands. Everybody hunts for the right saddle and you try on shoes to find a good fit but until recently there wasn't much variety available in grips. Sure there are a lot of patterns and thicknesses but they are all basically padded tubes over your bar. Then along comes a small Swiss company that is looked at the shape of the hand and made a grip to fit.
I've been running these for a while. The increased surface area and curvy shape is super comfy. I find they really help with bike control as well, because the varying shape keeps your hands from bouncing around and increases leverage when climbing. Ergons lock on with allen key collars so they stay in place no matter how wet the conditions.
Sole Custom Footbeds
Heat moldable insoles give your foot proper support. By replacing the stock, flat insoles in most cycling shoes, the foot is stabilized keeping the arch from collapsing and reducing foot fatigue on longer rides.
Little shims that go between your cleat and shoe, Lewedges can help correct pronation or suppination of the foot when pedaling. If your knee rotates in as you push down on the pedals these might just be what the doctor ordered. A stable foot will give you more power and less knee pain.
While there are a lot of good road pedals from a mechanical stand point, the Speedplay Zero and Light Action pedals are unique in the fitting options available. Three different axle lengths and two different adapter plates allow more adjustment to cleat placement than any other pedal system. I use longer axles and the rear mounting adapter plate to get my feet wider and cleats further back to deal with a stiff hip and heavy pronation on the right side. The Zero pedals are the only ones I've found that allow me to get my cleats placed so I can pedal pain-free. If you have a knee or ankle pain that won't go away these might be the trick for making riding enjoyable again.
FSA Shallow wing bar
Short reach, shallow drop and a level transition to the brake lever hoods make this the most comfortable bar I've ever ridden. Rather than put up with sore wrists and a drop position to low to actually use, check into these bars. Everyone I've setup with a pair loves the comfort and performance that comes from being able to use all of the hand positions and the bar.