So when you think of yoga, you might normally think of people with stick figure bodies who are able to take themselves into shapes that would injure a pretzel. Or quite possibly you think it would be great to be more flexible, that the additional flexibility may help prevent injury and improve both training and recovery. And you could have come to the conclusion that incorporating yoga into your training routine would be way to accomplish that. Quite honestly though, aside from the extreme, bendy postures, you may not see much difference between yoga and some of the more common stretches you've seen or read about. As a triathlete I know I didn't until I'd done yoga for a few weeks. That's when I got a taste of just how deep the rabbit hole that is yoga really goes. Let me explain.
The most notable difference between yoga and simple static stretches is the sequencing. Most good yoga classes follow a well thought out progression moving the body deeper and deeper into similar but more challenging positions. In fact many of the common poses you may be familiar with such as Downward Dog, Crow Pose, or even a simple Forward Fold are actually "preparations" for deeper yoga poses. The same is also true of many static stretches many of us have come to know and use regularly. Most common stretches are variations or simplified Yoga poses. Often what is going on in these variations or modifications is the pose is made more accessible by taking several dimensional components out of it so that they become available for someone new to using their bodies in an unfamiliar way. Static stretches (and most weight machines) often remove the coordinated muscle recruitment that relates to stability. The removal of this component, while making the stretch simple, has the undesirable side affect of doing less to actually strengthen the body.
One pose which illustrates this clearly is Uttanasana or Standing Forward Fold. When commonly presented, even in yoga classes, this posture is usually referred to as a mere hamstring stretch. And to see it performed it is easy to get that impression. If you were to merely fold forward without any direction, you would notice the pull at the back of your legs as you attempt to bring your chest in toward your thighs. But there is much more going on in this forward fold than meets the eye or a casual experience. For the fold to happen properly the hips are engaged as a hinge allowing the torso to move forward as the hips shift back. The spine extends out from the tailbone through the top of the head. As the torso is brought closer to the thighs, the thighs will have an inward rotation creating space for the chest. To deepen and hold the fold, the core must be engaged. This entire process allows the hamstrings to "release". Not stretch, "release".
This act of consciously "releasing" muscles is a distinction that gets lost in discussions of yoga versus static stretching routines. In this instance the difference between a forward fold stretch and Uttanasana is Uttanasana is in reality a handstand preparation where more and more weight is removed from the legs and feet and placed into the palms until the hips are directly over the shoulders and the legs are lifted from the floor. You can watch this same process outside a yoga studio in Olympic platform divers as they move into handstands prior to an inverted dive. The purpose isn't to stretch the hamstrings but to gain the ability to release them at will.
Downward Dog works in much the same way, encouraging access through the core, releasing the hamstrings, and preparing the body for the forward folds, handstands, and "floats" to seated positions and arm balances. These are all complex, coordinated movements, much like swimming so the connection is obvious, but mastering these movements can also greatly impact running and cycling by improving strength, range of motion, and economy.
A regular yoga practice can restore the coordinated function to many of the common stretches you already know about and to the other complex muscular activities you engage in. And it will aid tremendously in your recovery between workouts. One of the primary reasons for triathletes to get massages and take ice baths is to increase blood flow and fight inflammation after tough workouts. Think of yoga as an internal massage and an inflammation fighter too. By gaining coordinated muscular access, you recruit muscles more efficiently to perform all tasks from walking up a flight of stairs to riding 112 miles on a bike.