Both runners and cyclists in the past have considered the quads to be the primary muscles to develop for performance commonly leading to overbuilt, dominant anterior leg muscles.
The hamstrings are among the muscles responsible for running and cycling fast as they are involved in both knee flexion (bending and hip extension (torso straightening at the hip)). The hamstrings are also key decelerators- indeed the faster you can stop the quicker you can move again.
The Anatomy of Movement of Running and Cycling.
Understanding the hamstring almost needs a full anatomy lesson in what happens during movement and specifically how energy is transferred. More specifically the elastic power transferred from between one leg to the other leg during normal gait. Running in this case is different to cycling; running is a movement which relies upon elastic power being converted to kinetic power before being converted back to elastic power (think as you move from leg to leg).
In running the hamstring is stretched as the opposite leg swings forward, the pelvis maintains position as the hamstring stretches away from the torso trying to stabilize against rotational forces (this highlights the role of suitable core strength for runners who have symptoms of hamstring pulls or sore lower backs). As the foot transfers through the gait cycle there is a changing of emphasis of the muscles that are recruited. As the toe pushes of there is a transference in muscular recruitment from the hamstrings, glutes and erector spinae (back) to the abdominals, iliopsoas and the quadriceps muscle group. Broadly speaking this is a transfer between the muscles at the back of the body to the muscles at the front of the body. If the pelvis is in an incorrect position away from neutral it can make the transference of muscular recruitment difficult. Why? The torso has to stabilize against rotation and forward leaning. This can be seen in runners who lose control as they run, simply elastic energy transference is affected and the individual finds it hard to bring the swing leg through in front of the body. If as they push off on their toe there is too extreme a level of backwards movement (or the back hyper extends) it will result in the forward movement of the pelvis (often termed anterior tilt), this highlights that the knee does not need to travel backwards far past the hips in order to maintain pelvic stability. Great sprinters show this knee and hip position, if efficiency is leaked over 100 metres it can mean a difference of seconds. While in distance running efficiency is vital for quick times it is also vital for injury protection. Running in an uneconomical way can lead to poor joint position that loads the muscles and connective tissues and can ultimately lead to injury. If the hamstrings are tight it can pull the pelvis downwards posteriorally, tightness in this case limits the range of movement of the leg and limits stride length. If not strong enough anterior pelvic tilt occurs causing hyperextension at the lower back and possible back pain. Both may be related to hamstring pulls but for different reasons.
Cycling is different, when seated the pelvis is affectively fixed in a different position. As you do not have the elastic challenge to stability and transference from leg to leg, efficiency and leg power have to be built within relative few changes in environment as the movement is essentially closed chain. There is a need though to maintain pelvic stability and resist rotation (as in running). A stable pelvis leads to economical movement of the legs and therefore efficiency on the bike can be maintained. It highlights why leg power or strength is only task specific- most great sprinters would not come close to setting the world of time trialling on fire and vice versa.
The Myth of Sports Specific Training for the Hamstring.
So does this mean hamstring strength is trained differently? Well no, technique for runners and setup and technique are vital for both runners and cyclists. Beyond that though training the hamstring in itself is about training not just that muscle but the muscular balance between all the muscle groups that act around the hip and knee.
Most movements that operate through the hamstring tend to be ballistic- this highlights the necessity of the hamstrings to be able to control rapid lengthening. Hamstring training should initially be eccentric in nature; this means that during training there is an emphasis on controlling the lengthening of the muscle. This should also be multi-joint so that the muscles are recruited as a unit, not independent of each other- this is often where injury or overuse occurs. In regard to injury occurrence poor warm up procedures are blamed for hamstring pulls and strains. Type of warm up matters but specifically stretching the hamstrings effectively turns the muscle off, this increases the chance of injury as the muscle cannot lengthen under control.
Initially exercise selection to develop strength should consist of exercises such as stiff leg deadlifts, single leg deadlifts, step ups, and reverse lunges. These can progress towards walking lunges, cable hip extensions, glute ham lowers/ negatives and forward lunges. Beyond this technique training for both cycling and running can be reinforced. Bike work needs to be on the bike, variation of resistance can be used.
Dynamic hip mobility exercises for both cyclists and runners is important. Lack of hip mobility is a major cause of many hamstring problems. Without proper hip mobility the leg will not be able to work through the full range of motion. This limitation will eventually lead to flawed mechanics especially in a fatigued state as more limited ranges of movement will be worked through. These drills should be incorporated daily as part of warm-up or cool down and initially may be performed for posture correction reasons.
On a single leg the abductors and adductors play a major role in the stabilization of the hips. Resisted hip abduction helps strengthen the glute medius (vital for knee tracking). If they are weak or not coordinated with the hamstrings more strain will be placed on the hamstrings. Lateral resisted side steps with a rubber band placed above the ankles or the hips can be utilized as a warm up and cool down drill. This is quite effective for cyclists who can develop dominance in certain muscles leading to faulty knee tracking.
As for running, stair and gradient running is an efficient way of emphasising a high knee lift and powerful drive on toe off. Hill sprinting at a 15-degree grade provides an excellent means to develop good top speed mechanics. It is virtually impossible to overstride sprinting up hill and helps develop an efficient leg pick up from the hip flexors. Low hops and jumps serve to facilitate muscle stiffness which is more important for running than cycling. Stiffness does not mean necessarily mean tightness it means stability and quick transfer of movement, the opposite of stiffness would be the leg collapsing at ground contact. The emphasis here should be on the knee being slightly flexed with quick movements and low ground contact times. The key is in the ability to absorb force efficiently and transfer quickly.
This article has highlighted that subtle differences exist in the conditioning of cyclists and runners though there are more similarities especially in the gym that leads to optimum transfer to better performance.