Power Cycling Training

Perhapsunique among all endurance athletes, cyclists have the capability ofaccurately measuring their external work rate, or mechanical poweroutput, while “in the field,” i.e., on the road or track, throughcommercially available power-measuring systems such as the Polar S-710,Power-Tap, and SRM (Schoberer Rad Messtechnik) Training System.  Thesehold great potential as training aids, since power is an objectivemeasure of the stress load, or intensity, being imposed, and as suchdirectly determines physiological and perceptual responses to exercise.  Theyare particularly appropriate for road cycling, where the resistiveforces to forward motion vary greatly from one moment to the next inrelation to terrain, wind velocity and direction, changes in speed, androad conditions.  Indeed, many react withdisbelief at how “jumpy” the current power display is when using any ofthese devices for the first time, and question the readout’sreliability.  This is a result of having becomeaccustomed to the heart rate monitor (HRM) as a gauge of intensity, andbeing fooled by its delayed response to changes in intensity intothinking that the energy requirements of cycling are relatively steady, however, the accuracy of the power meter (and hence, the variable, or “stochastic” nature of on-road power expenditure) is verified by checking it against any constant-load indoor trainer. 

Cyclistshave at times taken their cue from distance runners in adopting pacingguidelines to gauge intensity for flat-terrain workouts.  Theconcept of goal pace and date pace was borrowed from perhaps its mostwidely known advocate, University of Oregon coach Bill Dellinger.  Thisapproach may have some reliability at a given velodrome, so long astemperatures do not vary significantly and the air is calm, but isunlikely to be useful on the road, even under ideal conditions, withthe possible exception of a standard (and sufficiently steep) uphillcourse.

The‘paradigm’ for measuring exercise intensity was changed in themid-1980s, when accurate, reliable, and affordable HRMs the size of awristwatch began to reach the consumer market. As becomes apparent when correlated with power, however,heart rate is limited not only by its slow response to changes inpower, but also since it can vary widely for a given wattage (muchmoreso during outdoor cycling, as compared to indoors on aconstant-load ergometer), due to physiological and environmental factors.  Indeed, had power meters preceded HRMs, the latter might have never been marketed and sold as a separate device.  

Intensity may also be gauged by “feel,” or perceived exertion (PE), either on a 10-point scale, or the original 6-20.  PEis subjective in nature, with its precision limited accordingly, andyet, perceptual responses to exercise are an important source offeedback during training, since they actually integrate morephysiological information than HR.  Still, only occasional reference will be made here other than to power as a measure of intensity.

Finally,power-based training has long been possible with a calibrated bicycleergometer, but the first power-measuring device for use “on the road”did not appear until 1988, when the SRM system was introduced.  Itwas followed by the Power Pacer (Balboa Instruments) and Look Max Onehubs in the early ’90s, neither of which was a commercial success.  SRM received a significant boost when it was embraced by several national cycling federations, as well as numerous professional  andelite riders, including Greg LeMond, but it took the Power Tap (1998,Tune Corp., purchased by Graber Products in late 2000) and Polar S-710(2001) to bring accurate and reliable power measurement within reach ofmost any rider.  (Ciclosport models are notmentioned here, since they make only a crude estimate of power, basedon weight, speed, and gradient.)

benefits of power-based training

1. It eliminates guesswork from gauging exercise intensity.  Even those with exceptional “feel” are unlikely to judge their wattage any better than to within perhaps 10%, whereas a power meter is accurate to ±2% or less.

2. It allows fitness to be precisely and accurately quantified and tracked, both daily and over time.  Workoutsbecome carefully controlled, and along with a periodized program,training is less haphazard, making peak performances easier to predict.  Carefully planned training may also help prevent overtraining and injury.

3.Power meters have other uses, such as pacing during interval training,time trials, and even breakaways in mass start races; aerodynamictesting; and possibly as an aid to dieting and weight control.  Previously,wind tunnel testing was necessary to assess air drag, but undercarefully controlled conditions, it may be possible to do this in thefield.