Food for Thought: What is the best cadence?

Thursday, June 30th, 2011

If you wish to maintain extended exercise duration, you need to exercise aerobically to reduce fatigue and lactic acid accumulation. When you engage in exercise, of low to moderate intensity, your body burns more fat because sugar and fat (glucose and free fatty acids) are the primary fuels of an aerobic metabolism.

By exercising aerobically, you maintain glycogen reserves by utilizing the sugar and fat in your blood stream. To extend your capacity to cycle for longer duration and distance, it is more advantageous to spin at a higher cadence (easy gearing) than to grind on a more difficult gear ratio. The more efficient cadence appears to be around 100 RPM.

Why? Lance Armstrong’s victories in the Tour d’ France had caused a lot of interest in this question, as we saw a dramatic difference in pedaling styles between Tour contenders such as Jan Ullrich, with his lower cadence, bigger gear style, and Armstrong, with his higher cadence, low gear form. Armstrong’s style appeared to be more effective with his mountain stage wins. Many scientists and coaches looked further into why this higher cadence style may be more efficient.

It seems that pedaling a higher cadences, (80+ rpm), is more efficient than slower cadences. One way to measure efficiency is by measuring oxygen consumption rates. This measures the metabolic “cost” of the exercise. In order to determine the cost of slower vs. faster cadences one study compared oxygen consumption rates, heart rates, breathing rates, power production and even blood lactate production of pedaling at 50 rpm vs. 100 rpm. In order to make the comparison, the athlete’s speeds were kept constant across the two cadences.

The result was that all of these indicators were very similar between the two cadences for the thirty minute test. One significant difference however, was the greater glycogen depletion in the slower 50 rpm condition. Looking closer, the researchers saw that only the fast twitch muscle fibres used more glycogen when pedaling at 50 rpm than they did when pedaling at 100 rpm. The slow twitch muscle fibres lost comparable amounts of glycogen in both the 50 rpm and 100 rpm conditions.

The slower cadence resulted in fewer, but more forceful contractions required to maintain the constant speed. It may sound counter-intuitive, but the higher force requirements of the slower cadence results in the recruitment of more fast twitch muscle fibres, since these fibres are capable of producing more force than slow twitch fibres. The drawback is that fast twitch fibres consume more glycogen, and fatigue more quickly than slow twitch fibres. As result, over the course of a workout, fast twitch fibres will get depleted and will fatigue. More fast twitch fibres will need to be recruited as the duration increase, which results in an increase of the total number of muscle fibres activated.

In addition, research has found that the faster cadence results in greater fat oxidation. Basically since slow twitch fibres are more efficient fat burners than fast twitch fibres, higher cadences that resulted in greater slow twitch recruitment used less glycogen, which is very important in endurance exercise performance. Over the course of a longer duration, the higher oxygen costs, and faster glycogen depletion seen in slower cadences results in reduced efficiency as compared to fast cadences.

Of course few cyclists would ever pedal as slowly as 50 rpm, but there are still efficiency differences, although smaller, between cadences in the 70s and lower 80s as compared to high 80s and 90 rpm plus. Slow twitch fibres can easily handle cadences of 100 rpm, but there is another factor to consider. When many cyclists do “spin ups”, or accelerations to a higher cadence, they find that they bounce on the saddle, and their pedaling form suffers. This is caused by a lack of neuro-muscular co-ordination at high cadences, which in turn negatively affects efficiency. The good news is that co-ordination is trainable, and with practice, pedaling at high cadences can be improved.

So the question remains: what is the best cadence? Examining high performance cyclists and triathletes seems to confirm that cadences of 85-95 rpm are optimal for most athletes, and for most terrain. With proper training at these cadences (at all intensities), the higher cadences will be more economical and thus will result in faster times on the bike. And there is an added bonus: since higher cadences result in more glycogen being spared, especially in fast twitch fibres, there is the ability to have a faster sprint to the finish.

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