Before we get to the good stuff, you need a quick anatomy overview. Nothing crazy, just a quick look: Your hamstrings are a group of three muscles on the backside of your thigh. They are called a two-joint muscle because they cross both the hip and knee joints. Since the group has lateral, and medial aspects, they have slight control on rotation of the thigh, but those actions are negligible and there are other muscles that do a much better job at that. So, for the purposes of mountain bikers, your hamstrings extend (or straighten) your hip and flex (or bend) your knee.
Hamstrings have a relatively fixed length, depending on your height and genetics. If you imagine them as a rope crossing pivot points at the hip and knee, pulling the rope taught on one end, will require it to shorten at the other end. You see this most notably in the highest part of the pedal stroke, where the hamstrings crossing the hip joint are “lengthened” and the hamstrings crossing the knee joint are “shortened.” At the bottom of the down stroke, you’ll see the opposite, with the knee extended and the “lengthened” portion of the hamstring, and the hip extended and the “shortened” portion of the hamstring. Muscles are innately flexible, and you can have an impact on how much range your joints can move against the force of your hamstrings through stretching.
All muscles have a preferred “length” at which they like to work and produce the most power. If a muscle is too short, the fibers are bunched and are too overlapped to produce any more pull. On the other hand, if a muscle is too long, the fibers aren’t touching enough to grab and pull together to produce force.
Consider the mountain biker below. With tight hamstrings further stretched with combined hip flexion and knee extension, the hamstrings have nearly no power.
While you can certainly argue that this position can be mitigated by dropping the post and bending the knees, if the roll down is steep enough, you may be forced to use a hip flexed-knee extended position, thereby shutting down the hamstring’s ability to produce power. While not pedaling in this position, you will be relying solely on your quads for knee and hip stability when they are already trying to hold provide stability for the body while the bike moves beneath it. This situation prematurely fatigues the quads, shutting your ride down early.
Additionally, If the hamstrings are too tight, the system must gain length somewhere and will do so by pulling on your pelvis, causing your low back to flex. This in turn follows up the spine, eventually pulling your torso into an upright position. This is not the position you want to be in when hitting a steep roll down!
If you force your torso to lower against this shortened pully system, you can experience back pain that can persist long after the ride, eventually taking you off the bike while you heal.
So how can you remedy this?
Hamstring stretching is the first step to improved position and performance on the mountain bike. While quick stretching directly before activity can actually reduce your short term performance, a consistent stretching regimen can improve your overall performance as you begin to have a good strength plus length relationship.
As I mentioned earlier, your hamstrings are a group of three muscles, and you must bias your stretch for each to get good results.
Grab a stretching strap, dog leash, belt, or towel and find a spot to lay flat on the floor.
- With your back flat on the floor, loop the strap over your foot, and gently pull your foot towards your head. You should not be feeling the stretch directly behind your knee. Tendons are not very flexible, so you want to move the stretch to the more flexible muscle belly. If this is happening to you, bend your knee slightly until you feel the stretch in the middle of your thigh where the muscle fibers have the most extensibility.
- Now angle your leg to point your foot towards the opposite shoulder. You should still feel the stretch in the middle of your thigh, but now towards the outside.
- Change the angle of pull with your leg towards the outside, beyond the shoulder on the same side. You should feel the stretch in the middle of your thigh, but towards the outside.
- Hold each of these angles of stretch for 30-40 seconds, and then repeat the sequence on the other leg.
- While trying to gain flexibility, you should perform these stretches 3 times daily, 5 times weekly.
Using this method of stretching instead of the old version of sitting on the floor and reaching to your feet isolates the stretch to the hamstrings, and reduces strain on your lower back. This stretch should never be painful, so vary your pull and angles until you can feel a stretch without pain. Don’t be too aggressive to start. You’ll get more flexibility with a consistent stretching routine.
As always, consult your doctor before beginning any fitness routine. If you should experience pain during stretching, consult your doctor or physical therapist.