bike

Triathlon Magazine Canada - - CONTENTS - by Erinne Wil­lock

FInd Your Op­ti­mal Cadence

Are you a grinder who’s con­stantly be­ing told by coaches and train­ing part­ners to go to an eas­ier gear and spin faster? Maybe your cadence is too high and push­ing a lower gear makes your legs feel like ce­ment. Is there re­ally such a thing as the per­fect cadence? Triath­letes and cy­clists have long con­sid­ered 90 rpm as the ideal. But, what do we re­ally know about cadence and max­i­miz­ing ef­fi­ciency? As it turns out, not much.

Oliver Blake, a PhD can­di­date at Si­mon Fraser Univer­sity, is study­ing the biome­chan­ics and mus­cle re­cruit­ment pat­terns in cy­clists. He ex­plains that choos­ing the ap­pro­pri­ate cadence is highly in­di­vid­u­al­ized and also de­pen­dent on the level of in­ten­sity re­quired. He in­sists, “If ab­so­lute max­i­mum power out­put is re­quired then the cadence is go­ing to be around 120 rpm, whereas in­ter­est­ingly, the one hour dis­tance time-trial record is al­ways set around 100–105 rpm and road dis­tance cy­clists will tend to use 90–100 rpm.” But all of us know pow­er­ful cy­clists who never get out of their big ring even when climb­ing and yet al­ways ride fast.

Wattage, or power out­put, is gen­er­ated in two ways. The first is through torque or how much force is ap­plied to the crank arms. The sec­ond is through cadence or rpm ( how fast the crank arms are spin­ning). Es­tab­lish­ing the most ef­fi­cient bal­ance be­tween the two de­pends on many fac­tors in­clud­ing in­di­vid­ual phys­i­o­log­i­cal makeup.

Phys­i­o­log­i­cally speak­ing, there are two com­po­nents to con­sider. First, when cadence de­creases at a given work­load, the torque or mus­cle force re­quired must go up in or­der to main­tain the same wattage. This takes a greater toll on the work­ing mus­cle groups.

Greater mus­cle force at lower rpm of­ten taps into fast-twitch mus­cle fi­bres, which in turn burn mus­cle glyco­gen more quickly than slow-twitch fi­bres. This has huge im­pli­ca­tions for en­durance events like triathlon. Mus­cu­lar fa­tigue af­ter the bike can leave an ath­lete with lit­tle left in the tank for the run. Com­bine that with a larger de­crease in mus­cle glyco­gen and it’s not a great way to set one­self up for the long haul. But, if spin­ning at a higher cadence fa­tigues rid­ers with more power and less of an en­durance base, the slightly lower cadence may be the best bet.

The sec­ond com­po­nent to con­sider is the stress put on the heart and lungs (the aer­o­bic sys­tem). As cadence in­creases while main­tain­ing a con­stant wattage, more power is gen­er­ated through rpm so less torque is re­quired. This is less stress­ful on the mus­cles but will tax the heart and lungs. The more aer­o­bi­cally fit you are, the more favourable this op­tion may be. There is of course a limit to how high rpm num­bers can get be­fore the ben­e­fits wane due to the speed of move­ment and mus­cle co-or­di­na­tion re­quired.

In a con­trolled race like a time trial or iron dis­tance bike seg­ment, if you are aer­o­bi­cally very fit and have trained to achieve higher rpm num­bers then it may be ben­e­fi­cial to hold a higher rpm in or­der to save your legs mus­cu­larly for the run. How­ever, there isn’t a magic num­ber for ev­ery in­di­vid­ual or sit­u­a­tion. Ideal cadence will dif­fer depend­ing on ef­fort, fit­ness level and the de­sired out­come.

A be­gin­ner will have a much harder time hold­ing a high aver­age cadence than a pro­fes­sional ath­lete. It can take years to de­velop the mus­cu­lar co­or­di­na­tion to sus­tain a higher cadence over an ex­tended time pe­riod. Ac­quir­ing this skill is a good strat­egy in triathlon be­cause it should cre­ate less mus­cu­lar fa­tigue and help ath­letes uti­lize more slow-twitch mus­cle fi­bres.

What we know for sure is that cy­clists who are more ver­sa­tile are more likely to per­form bet­ter in dif­fer­ent sce­nar­ios and on dif­fer­ent race cour­ses. It en­sues there­fore, that we should learn to be com­fort­able at both higher and lower ca­dences. For this, cy­clists can do spe­cific rpm drills with a cadence sen­sor to switch up their ca­dences. One such drill is the Cadence Pyramid. This is usu­ally done in­side on a trainer or rollers with very lit­tle re­sis­tance. The rider starts at a lower cadence of 80 rpm and builds up to a higher rpm and then goes back down. Each step is held for one minute.

Over a few weeks aim to build up to 130 rpm at the top of the pyramid. Prac­tic­ing dif­fer­ent ca­dences will also help your neu­ro­mus­cu­lar re­sponse time and make you a more ef­fi­cient cy­clist.

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