Cadence: as the pedals turn…..
Dr. Ivo F. Waerlop, Dr John Asthalter
To spin or not to spin, that is the question. How do you know how fast (or slow) is right? The answer lies in the analysis of style. What are you trying to accomplish? Cardiovascular efficiency? Strength training? Just going for a cruise?
Early research into optimal cadence recommended 40 to 60 RPM’s (whoa, kind of slow, unless you’re pushing big gears). This research unfortunately focused on unconditioned civilians on stationary bicycles, not experienced cyclists on their own bikes. They also were performed over short intervals of time using oxygen uptake (i.e. VO2 max) as their sole basis of performance. When the experiments were repeated with trained cyclists on their own bikes, the numbers were more in the vicinity of 80-120 RPM’s (aahh, that’s more like it).
Lets look at some physics to explain things. Lower cadences generate more torque. This is needed to help you climb hills and blow past your competitor. Contractions of your leg muscles are slower and more forceful. Strength is gained because you are pushing your muscles to their physiological limits, forcing them to contract at near full capacity, activating the maximal number of muscle fibers. There is a point of diminishing returns. As you muscles contract harder, they are diminishing their own blood supply, because they are physically squeezing the capillaries closed (think about how much larger your muscles are when you work out). This cuts off the flow of oxygen and other nutrients to the muscle. The muscle is also creating a lot of lactic acid ( a by product of metabolism) which in turn inhibits the muscle from contracting and creates that burning sensation you experience during a big work out. This lactic acid production is evident when trying to climb a hill pushing too big a gear.
Lower cadences and big gears also result in greater pressures under your patella (knee cap) and greater strains on you knee joints. If you have any degree of misalignment (as is common in women, because they have wider hips and an increased angle between their thigh and lower leg) or have abnormal or aberrant lower extremity mechanics (patellar tracking problems, chondromalacia patella, TFL tightness), they will soon become apparent (and often very painful).
At higher cadences (>100 RPM’s) you tend to build endurance of your muscles and cardiovascular system more than strength. The strength of contraction is actually less which helps to allow a greater degree of blood flow. Once you get above 120 RPM’s, friction between muscle layers increases, and more of your energy goes to producing heat, rather than strength. Higher cadences also produce less stress under your patella, so often times, less knee pain.
Body types and crank lengths, along with riding style also come into play. Bigger, beefier riders tend to push higher gears, so their cadence is naturally slower. The same applies to people who use longer cranks. Some people like to “feel the burn in their legs”, so they push bigger gears and go slower, while others like to “feel the burn in their lungs”, so they push small gears and go fast. The rest of us use some combination of each.
So, to turn or not to turn? You have to ask your self what you are trying to accomplish. Trial, error and experience are often the best teachers. When in doubt, it’s usually better to faster than slower and less resistance vs more. Keep it challenging but not painful. When in doubt, consult with a professional.