By John Howard
My larger hope is that we can make you more efficient on your bike. We need to maintain constant power for the duration of our event, irrespective of the distance or time. Achieving this goal is a formidable challenge for any athlete and bike fit and biomechanical function are two of the main interconnecting ingredients for success.
In order to better understand the relationship between fit and function, we need to look at two factors: power and stabilization. If you pick up the coloring book and start coloring in the muscles, you will begin an educational understanding of muscle location, origin, insertion and action of those muscles. This equates to a better understanding of stroke mechanics. Keep our goal in mind – that of greater power, improved efficiency with a reduction in heart rate.
For the purpose of clarification, let’s think of your body as a football field with players in the offensive and defensive positions. We can identify the backfield agonists, or power-producing muscles in the downward stroke, and defensive side that have a stabilizing antagonist effect of lifting the muscles of your pedal stroke. The big power players are the gluteus maximus and hamstrings that fire during hip extension in the backfield, and the “show off” quadriceps group which work as lower leg extensors.
The smaller, lower leg gastrocnemius and soleus completes the power stroke during plantar flexion with a slight toe-down lead on the foot. This toe drop is necessary for an efficient pedal stroke although not well understood. On the opposite side of the stroke, we have the lifters. The psoas, rectus femoris and sartorius function as hip flexors, while the multi-purpose hamstrings work as lower leg flexors. Very briefly, the tibialis anterior (front of the lower leg) dorsiflexes the ankle at mid-stroke (9 on the clock face). This explains why the tibialis anterior muscle often fatigues during hard driving workouts on the trainer.
The secondary stabilizers are akin to a defensive front line in a football game. The antagonistic stabilizers include the adductors of the hip such as the gluteus medius and minimus. Also contributing to the stabilization are the tibialis anterior which counters the gastrocnemius, soleus and tibialis posterior. When turning very fast rpms or high wattage on a trainer or rollers, the tibialis anterior muscles see heavy stress and actually have a power function in cycling. Other muscles, including the trunk and scapular stabilizers, are used for stabilizing the core, shoulders and neck. These are used mostly in long, sustained efforts during time trialing. They might also be used to a lesser extent to provide endurance stability for longer time trial events such as an Ironman distance bike leg and ultra distance cycling.
Power from the down-stroke is produced by the extensor muscles, and the flexors do the lifting. If the cyclist is pedaling at 100 rpms, the transitional periods of extension and flexion are extremely brief.
Pedaling imbalances and how they happen. The transitional periods mentioned above can lead to slight hesitations or “dead spots” in the stroke. These dead spots are more easily observed in novice cyclists who have spent little time improving their stroke mechanics. Multi-sport cyclists or winter restricted riders who do most of their cycling on spin bikes will eventually develop an over-dependence on the free-flowing loaded fly-wheel, used predominately on the popular spin bikes. This will serve to diminish the antagonistic action of hip flexion and eventually knock your pedal stroke out of balance. We strongly recommend you use your own bike on a trainer or rollers for the bulk of your indoor seasonal training.
Cycling by its nature is a forward momentum-producing, concentric exercise with virtually no lateral or eccentric loading taking place. Of course there are exceptions to this, including cyclocross and mountain biking, but for the most part we have nearly complete reliance on flexion and extension movements, virtually exclusively in the sagittal plane. As the activity increases in longevity and intensity, imbalances are more probable. The most obvious examples can be observed in the poor, stooped posture of ultra-distance racers. This is usually accompanied by a sharp trigger point pain in the upper back and neck.
Age is not your ally in this struggle to maintain biomechanical balance. Eventually, if left unchecked, the neck and scapular stabilizers become severely compromised. Hip abductors show the effects by decreasing pelvic/hip stability. The critical stabilization of the quadratus lumborum (QL) affecting low back stability is also the function of the gluteus medius and minimus.
The bad news is that cycling does not really do a great job of strengthening the gluteal muscles. When the QL begins to weaken, power from the primary muscles used in extension beginning with the gluteus maximus begin to diminish. As pressure builds in the low back, the TFL contracts and the iliotibial band begins to tighten, placing an additional load on the insertion point near the outside of the knee.
The resulting pressure comes in the form of a dull ache or sharp pain with a weakening of the quadricep muscles. In short order the cyclist’s driving platform is diminished. In over-compensation, the primary core muscles of the erector spinae give up their stabilizing function resulting in an increasingly deepening dull ache in the QL (low back) and a continuing downward spiral in terms of power availability. This low back pain remains the number one complaint for most of my coached masters cyclists and triathletes.
Measuring Imbalances On A Trainer
Field testing imbalances is often a therapeutic necessity if maximum cycling performance is to be achieved, maintained or re-established. At John Howard Performance Sports our favorite testing tool is the CompuTrainer Spin Scan, which measures an array of muscle functions including torque and power. It also measures average torque angles, which generally relate to percentages of overall torque. Both measurements split left and right muscle group usage, and is displayed on the polar graph.
A power meter can also be creatively applied to test legs for output in Single Leg Drills (SLD). The standard power meter can also be used to detect output variations for left and right legs. An example of an effective protocol includes 2-3 sets of 30 to 45-second drills for left and right, then testing for power and/or heart rate. It should be noted that when the crank begins to “click” it is an obvious sign that the muscles have fatigued to the extent the exercise is no longer meaningful and therefore the interval training should be stopped or shortened. The correction procedure might include 10% more activity on the weaker leg with an appropriate rest interval to insure a strength gain.
Included in our BodyFiTTE program which I will explain in future complementing articles, are several exercise ball components that will quickly illustrate hip stabilizer imbalances. For a more quantitative hands-on approach to discovering muscle imbalances, we recommend a refresher session with one of our approved FiTTE professionals. As with any testing procedure, in order to accurately quantify the results, testing needs to be repeatable as closely as possible with similar conditions at different intervals during the year.
Once you finish coloring in the various muscles in your Anatomy Coloring Book, you will find that you will have a better understanding of their intended function which will enable you to isolate the muscles and fire them with more panache.
Condevaux, Bernard, PT CSCS, Performance Conditioning Cycling Vol. 12, No. 3.
Ernie Ferrell, DC, CCSP
Gina Poertner, CHES
John Howard is one of the pioneers and true legends of American bike racing, with palmares including: 3-time Olympian, Ironman world champion, bicycle landspeed record, USA Cycling Hall of Fame, and elite and masters national champion. John is also an active cycling coach and the author of Mastering Cycling. Check out more information about John and his coaching at www.fittesystem.com and www.johnhowardsports.com.