Preventing Hamstring Fatigue During Cycling
by Ken Mierke
Most of a cyclist's power should come from the gluteus maximus and quadriceps muscles during the downstroke. These muscles combine to extend the upper leg at the hip and the lower leg at the knee. Other accessory muscles should be involved, but should not fatigue greatly and certainly should never be a limiting factor in cycling performance.
Many cyclists find the hamstring muscles fatigue quickly when they ride hard. Multisport athletes, in particular, need to be sure to keep their hamstring muscles fresh because they are so crucial for efficient running after the bike. If your clients suffer from hamstring fatigue while riding, or when they run off the bike, make the following adjustments to their technique. They will be able to ride faster, further, and without hamstring pain.
The way the hamstring muscles attach creates one difficulty for cyclists. Since the hamstring crosses both the hip and the knee joints, it has two major functions: hip extension and knee flexion. During all 360 degrees of the pedal-stroke, a cyclist undergoes either hip extension or knee flexion ... so the hamstring muscles potentially contract throughout the entire pedal-stroke without a moment to recover. No wonder they fatigue for so many riders.
Each muscle involved in the pedal-stroke must have periods of relaxation during which they recover from the powerful contractions they have just been required to produce. The key is learning when the hamstrings are required to produce power in an efficient stroke and when they should be relaxed… and then learning to pedal that way.
Downstroke: Most of a cyclist's power is released during the downstroke. This phase of the pedal stroke, when performed properly, overlaps power output from hip extension (gluteus maximus and hamstrings) and knee extension (quadriceps). Misunderstanding how power should be applied during the downstroke causes many riders to lose this crucial overlap and overuse the hamstrings.
Many cyclists begin the downstroke late, at about 2 o'clock and direct the power produced directly downward. This separates the optimal torque ranges of hip extension and knee extension and calls the hamstrings in to play excessively. Since the quadriceps muscles are not activated properly, almost all the power must be produced by hip extension. To accomplish this, the hamstrings must contract very forcefully.
In an ideal downstroke, the power application begins early, at 12 o'clock, and is directed downward diagonally toward 4 o'clock. This activates the quadriceps optimally and lengthens the overlap between the peak torque production of knee extension and hip extension. The quadriceps and gluteus maximus are the primary power producers and the hamstrings contract moderately.
Backstroke: Power production during this phase of the pedal stroke is critical for effective climbing. Each pedal stroke reaches a crisis moment when one pedal is at 12 o'clock and the other is at 6 o'clock. Since neither leg is engaged in a downstroke, creating a little bit of power in this 'dead spot' carries momentum through to the next downstroke.
The backstroke is one area of the pedal stroke where the hamstring muscles should be very active, because only knee flexion provides power in this range. Relaxation during another range of the pedal stroke in (upstroke) prevents fatigue and enables powerful backstroke contractions without over-using the hamstrings.
A primary weakness of many riders is extending the downstroke too long and starting the backstroke late. This prevents the rider from unloading before bottom-dead-center and causes wasted energy pushing downward when the crankarm is moving directly backward.
I teach riders to begin the downstroke at 3 o'clock, trying to pull the heel straight back, directly through the bottom bracket. Obviously they can't do this, but the downstroke is such a naturally dominant aspect of the pedal stroke that it will finish itself without the rider's concentration.
Mentally triggering the backstroke early helps a rider to unload by bottom-dead-center. Every rider continues to press down at 6 o'clock. Obviously this is wasted energy. Only power directed at a tangent to the arc described by the pedals propels the bike. More economical riders press down at 6 o'clock less, having learned to begin the backstroke earlier. Their power production more closely resembles the back and down arc followed by the pedal. Attempting to begin the backstroke at 3 o'clock gives a rider the best chance of timing the transition from downstroke to backstroke optimally. I don't think any rider ever initiated the backstroke too early.
Upstroke: Most cyclists create negative power during the upstroke, actually pushing down on the pedal and negating some of the power of the other leg's downstroke. During steady state riding, efficient riders lift the weight of their foot, leg, and shoe during the upstroke. They avoid creating negative power during this phase. We call this 'unloading' and it allows all of the leg's downstroke power to contribute to propulsion instead wasting energy lifting the opposite leg. This aspect of pedaling is critical. Unloading on the upstroke is one significant difference between elite and intermediate riders. Without correct unloading, the right and left legs actually fight against each other.
The movements of the upstroke are hip-flexion (lifting the knee) and knee-flexion (lifting the foot). Since the hip-flexors are active only in this range of the pedal stroke, they should be the primary muscle contracting during this phase. Since the hamstrings are active during the backstroke and somewhat active during the downstroke, efficient riders relax them during the upstroke phase.
Attempting to pull up on the pedal through this phase places too much concentration on knee flexion and prevents hamstring relaxation. The hip flexors, once trained, are extremely fatigue resistant. They are only active for about 25% of the pedal stroke. Obviously they can contract very powerfully with a 1:3 work to rest ratio. Use the hip flexors and not the hamstrings is crucial. There are two keys to taking advantage of the fresh hip-flexor muscles and resting tired hamstring muscles. The first key is keeping your concentration on lifting the knee and not the heel or the foot. If a cyclist thinks of lifting the heel or pedal or foot, he is likely to use knee flexion to accomplish the movement. If he thinks of lifting his knee powerfully, the foot and pedal will follow without contractions to bend the knee.
The second key is thinking of the upstroke as a diagonally upward / forward movement, instead of an upward and backward movement. Again, this places the emphasis on the hip-flexor muscles, which should be contracting, instead of the hamstrings, which should be relaxing. When your pedal reaches the seven o'clock position, think of driving the knee up toward the handlebar.
Summary: To use the hamstrings to generate power effectively and rest them when appropriate, remember these keys.
- Try to feel that all the power is created in the top ½ of the pedal stroke.
- Begin the downstroke early, pushing down diagonally from 12 o'clock towards 4 o'clock.
- When the pedal reaches the 3 o'clock position, initiate the backstroke. Try to pull the heel directly backward through the bottom bracket. This will not actually happen, but attempting to will encourage the optimal stroke.
- When the pedal reaches the seven o'clock position, pull upward and forward with the knee. Concentrate on using the hip flexor muscles, located in the front-hip and upper-thigh area, and relax the hamstrings during this part of the pedal stroke.