Haven't found much info on this, but I figured out how to animate springs and flex tubing...Here's how:
For springs, you have to create the spring while in assembly mode:
1. Insert > Component > New Part
2. RMB on the new part in the model tree and "edit part".
3. Sketch and constrain a line between 2 components that the spring is interacting with. This is the centerline axis of the spring.
4. Sketch and constrain a wire diameter profile.
5. Create a swept boss/base using the line as the path and wire dia as the profile. Under options, select "Twist Along Path" in the Orientation/twist type box. Define the spring by "Number of Turns".
6. That's it! Drag or move the component that the spring is interacting with and rebuild to see your spring stretch and compress. In animation mode, drag the time bar to the desired time. Move the component that the spring is interacting with and start the animation.
After learning this, I found this great tutorial which explains it better than I can: http://youngdutchdesign.com/pressuresprings-in-solidworks
For flexible tubing, you also have to create it in assembly mode:
1. Insert > Component > New Part
2. RMB on the new part in the model tree and "edit part".
3. Sketch and constrain 2 or more lines between 2 components that the hose is attached to. This will act as your pivoting linkage.
4. Sketch a spline and constrain the spline points to the ends and linkage pivot points.
5. Sketch and constrain a tubing diameter profile.
6. Create a swept boss/base using the spline as the path and tubing dia as the profile.
7. That's it! Drag or move the component that the hose is interacting with and rebuild to see your hose stretch and compress. In animation mode, drag the time bar to the desired time. Move the component that the hose is interacting with and start the animation.
This video should help make some sense of it all. The red lines are your linkages and the blue spline is your path. I made both straight tubing and a coiled spring to show the power of this method.