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The Case for Cadence If you are an injured athlete, and your problem revolves around leg pain while running or cycling, then you may have cadence as one underlying cause of your problem. Adjusting (usually increasing) cadence on the bike or the run is often the major change required to stop the pain that is the primary reason athletes have sought our services in the past. Injury and pain in athletes has many causes but the physics of injury are such that changes in cadence can reduce the abnormal or excessive forces that are commonly the major underlying cause. Cadence is a major issue for runners, since for any given run speed, a reduction in cadence by increasing stride length rapidly increases impact forces and shear stresses in the legs. The instantaneous acceleration and deceleration that occurs with each stride in many parts of the leg increases as stride lengthens. This happens at the muscle attachments (read shin splints), at the musculo-tendonous junction (read torn Achilles tendons), and in the fascia layers (read ITB syndrome & plantar fasciitis). Additionally, as a runner increases stride length the increase in acceleration/deceleration is worse if they are a heel strike runner. As coaches and health care experts, we also have to consider both the rate of change in the athlete activity pattern and the total amount of activity to determine the underlying cause and appropriate treatment. Many common injuries, such as patellar tendonitis for example, occur due to a spectrum of simultaneous events. In the acute syndrome, recent increases in total training volume together with slow cadence are often present together in the same athlete. As a heel strike runner shortens stride and increases cadence, she usually makes speed gains. . A long stride heel strike runner almost stops with each heel strike. That deceleration tends to stop the runner, forcing her to re-accelerate during the latter half of each running stride. Changing to a shorter stride and increased cadence forces the runner toward a mid-foot strike and hence reduces the deceleration that was occurring with each heel strike. Cadence issues for cyclists have a different wrinkle since there is no impact force in the cycling pedal stroke. However, as pedal stroke cadence decreases, the force that must be exerted during each stroke increases for any situation of constant power output. Generally speaking, for otherwise identical conditions, power output is well correlated with speed on the bicycle. The increases in the forces exerted by each leg during each pedal stroke are very important since there are literally millions of pedal strokes for any serious cyclist or triathlete per racing season. Shear stresses in the knees are also increased during the power portion of your pedal stroke as cadence decreases. Increases in shear stress between the bearing surfaces of the knee may increase the risk of cartilage injury, or may further damage cartilage that is already damaged. Since as adults our cartilage surfaces heal poorly or not at all, damage of any kind is important since progressive loss of these surfaces results eventually results in arthritis and pain. The only practical solution available to the athlete when their cartilage surfaces are gone is surgical joint replacement. This is called total joint arthroplasty (TJA). TJA is not the end of a cycling career, but certainly will slow your season! We know of a number of older athletes that cycle very successfully after TJA. That being said, reduction of shear and compression stresses at the knee by increasing average cadence, will often allow those of us with enough cartilage damage to cause pain with activity to cycle, even to race again. Often cartilage damage is worse in one section of the knee, so additional changes to the bike set-up to reduce stress in the portion of the knee that has the most damage of often necessary. Usually we more mature adults damage the inner (medial) knee surfaces worse than we injure the outer (lateral) surfaces, so the most common direction we head in is to increase the cyclist's “Q” distance on the bike to reduce medial knee loads during the power portion of their stroke. The Q distance is the distance from side to side between your pedals. Cadence and crank length also interact in cycling. As you lengthen your pedal crank and/or slow cadence (and hence use a bigger gear), the tension in your patello-femoral complex (The knee cap and the tendons above and below connecting it to the tibia(shin bone) and quadriceps muscle complex(thigh muscle)) progressively increases during the power portion of your pedal stroke. Either too much total tension, or too rapid an increase in training, then leads more rapidly to patellar tendonitis if cadence is too low. As an active athlete achieving useful increases in cadence is more difficult than it may seem at first. Left to our own preferences most of us tend to run and cycle at cadences in the 70-85 range. Also, on the bike, pushing a larger gear at a slower rate just feels good for many athletes. For a host of reasons, practically speaking, training oneself to run and bike at a higher cadence such as 90 to 110 usually requires that we purchase an audible metronome for running and a cycle computer that has a cadence readout. At least weeks to months of training consistently at a new, higher cadence are required for your new cadence to begin to feel natural and comfortable. Seiko makes a relatively inexpensive audible metronome for running, available for less than $25. Its only fault is that it is not waterproof. If you are going to race with it and pour water and ice over yourself to keep cool as I do, then you'll need to use this device in a small Ziploc bag to keep it dry. The smallest snack bags are OK. We both train and race with these handy gadgets, and have discovered that a cadence of 92 for shorter races and 90 for longer ones works for us. Faster runners may need to use a cadence in the upper 90s. Cadence computers for bicycles are widely available, with the probably the least expensive wired ones available from discount retailers such as; http://www.performancebike.com You can spend whatever you want on a cycle computer that has cadence, up to several thousand $$ for the most sophisticated ones that also measure power output. One issue about cycle computers is that if you want to have a computer that is useful when both when using a trainer and one the road, then you must find one that measures speed from the rear wheel. Cadence is always measured in some fashion associated with pedal rotation. For those of us that are triathletes, there is an additional benefit from learning to ride at cadences from 90-110. If you, the reader, are using traditional time trial riding at cadences of 70-85; then increasing your cadence will usually allow you to run faster at least in the early miles of your run. This benefit apparently occurs whether or not you are using an aggressive forward seating position or a position closer to the traditional road cycling position. In summary, attention to cadence usually means teaching yourself as a runner or cyclist to use a higher cadence than is your natural tendency. Cycling and running at higher cadence rates clearly reduces peak and total stresses of numerous types in several parts of your body thus reducing your risk of injury. Changing cadence may also be part of the path to recovery from injury.
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