Power and Acceleration?

Discussion in 'Power Training' started by PowerPunk, Jun 14, 2005.

  1. PowerPunk

    PowerPunk New Member

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    I've noticed that when I'm in the middle of intervals holding a certain power range, and the road turns down or the wind picks up or something, that it can be very difficult to maintain the power range while accelerating. Even if I'm at a moderate power level, the perceived effort while accelerating but holding steady power is much higher. Anyone know what is going on? My first thought is that since I'm accelerating, more effort is required - but - I'm keeping power constant.

    Also, I've noticed that holding a steady power level while descending "feels" harder than on the flats. Why is that? Looking at my files, it appears that while climbing, torque goes up as power stays steady, and while descending, torque goes down while power stays steady. But descending "feels" harder than climing at a given power range. If torque can be associated with pressure on the pedals (? - powertap, not SRM), then the higher perceived effort is not because I'm pushing harder??
     
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  2. drewjc

    drewjc New Member

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    What does your HRM tell you when you start a descent or tailwind section on your rides? (i believe it would go up if you hold a steady power output???) From my basic knowledge of the figures associated with pedalling, power, force, torque, cadence etc. i would assume that the rise in cadence associated, with the required acceleration to maintain a steady power output has raised your perceived effort (and possibly your HR) beyond your comfort range.

    The basic point is that cadence has a greater effect on perceived exertion than does torque. To determine POWER you simply multiply TORQUE x CADENCE, so if your torque is dropping on a downhill section then your cadence (the second variable) must increase to hold the same power, while the opposite is true for an uphill or headwind (ie. increased torque, decreased cadence). It is these changes in cadence that i believe are affecting your perceived effort. Many people don't realise cadence can play such a big part in determining HR.

    In an ideal world with constantly variable gear ratios the gears would increase so that you could maintain a constant cadence (one that is comfortable for you to work at) with only your torque and actual speed changing.

    The point is that your higher perceived effort is from an increased cadence and not an increase in torque. It is easier for the body to adjust to small changes in torque required but an increase in cadence upsets you more than you might realise.
     
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