PezCycling News - What's Cool In Pro Cycling : Toolbox: Cadence Specificity

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Toolbox: Cadence Specificity
Tullio Campagnolo’s derailleur completely revolutionized the modern bicycle, giving us up to 22 gears to play with in an effort to find that ideal combination of cadence and resistance to maximize our power output over a range of terrain. But when it comes to training, does training with specific cadences have their benefit?

Quick commercial blurb: At long last, Stephen’s book on the science of cycling, “Cutting Edge Cycling,” written with Hunter Allen, is about to hit the bookshelves late April 2012. You can pre-order a copy signed by both authors through Peaks Coaching Group.

In the early days of cycling, all road bicycles were single speeds or, at best, required completely taking out and putting the rear wheel back in the other direction with a different rear sprocket. Contrast that with the rise of the rear derailleur, and also the ever-increasing number of gears on the rear wheel. In the mid-1980s, my first high-end racing bike had a 6-speed freewheel for 12 total gears. And now Campy has found a way to jam 11 gears into the rear cassette.

So nowadays and especially with STI/Ergopower/DoubleTap, there’s really no excuse for being in the wrong gear, but just what does being in the right gear entail? The right gear for cyclists typically means the highest possible power output in whatever terrain from our finite pool of energy, and this does not always mean the biggest or the smallest gear, but generally something in between.

The Force-Velocity Relationship
Mainly, this “right gear” comes down to our muscles’ force-velocity relationship. Namely, the amount of force that our muscles can exert is greatest with an isometric contraction (where the muscle doesn’t change length – think of pushing against a rock wall with your arms). As your muscles contract faster, the amount of absolute force that the muscle can generate decreases exponentially.

Now remembering that power output is force x speed of movement (i.e., an isometric contraction, where you have maximal force but zero speed and hence zero power output), what you get is an inverted-U shaped relationship between cadence and power output. So getting the highest power output does not always mean slamming it into the 53×11, because if you can’t get the gear turned over at a decent cadence, you won’t be generating much power. Similarly, we’ve all experienced “spinning” out a gear where your cadence may be >100 rpm but your power output is very low. End result, at any power output, you need to pick the right gear at the right cadence in order to maximize power output.

Un-Optimizing Your Training
The above is all well and good while racing, but what the force-velocity and power-cadence relationship means is that, even at a constant power output, we can vary the stress on our body by varying our gearing and therefore cadence. A simple example is doing intervals over the same course in either a 53×12, 17, or 21 gear. Each gear choice will place more or less stress on your muscles, which can be seen in the torque profile of your power meter.

So this raises the question – is it beneficial to do intervals at possibly a lower cadence/bigger gear than normal to enhance muscular adaptations? Or if your goal is a flat time trial, does it make sense to train with hill intervals, where the cadence might be lower and the muscular stress higher? Or if you’re targeting a hill climb championships, do you need to find hills for training or can you make do with flat intervals? Just how much specificity does your body require?

Nimmerichter et al. 2012
The idea of training at a “non-optimized” cadence was tested in a new study in the European Journal of Applied Physiology by an Austrian research group (Nimmerichter et al. 2012). The general context was training for either an uphill or a flat time trial by primarily training with uphill (low cadence) versus flat (high cadence) intervals.

Study details:

• 18 trained cyclists as subjects. They had been training > 5 years, and averaged nearly 12 h/week of training for the 12 weeks prior to the study.

• Subjects were split into 3 groups for 4 weeks of training, each training with two interval sessions per week. Training and test results were tracked with SRM.

• Group 1: uphill (60 rpm) intervals

• Group 2: flat (100 rpm) intervals

• Group 3: control. Steady training but no intervals.

• Pre/post the 4 weeks of training, subjects performed a graded ride to exhaustion, and also 20 min time trials in both uphill and flat conditions on the road. The uphill course was 7 km and averaged 8.5%, with a best-ever time of ~19 min. The flat route was 15 km, with an overall rise of 64 m.

• Interval training was 6×5 min at their respiratory compensation threshold (think steady hard but not fall-over hard effort) on a set uphill (7.2% grade, ~60 rpm) or flat (1.1%, ~100 rpm) course, depending on group.

• An unavoidable side effect of the experimental design was that power output was not constant between the two types of interval training.

Making the Grade
So what happened with the different training programs?

• All groups slightly but significantly increased their overall training volume, with no differences between groups. Not surprisingly, overall ratings of perceived exertion were higher in the two interval compared to the control group.

• With the graded exercise test, all groups increased their final power output, along with the power output at their respiratory compensation threshold. No differences in results were evident across training groups.

• With the flat time trial, both the uphill (+1.5%) and flat (+2.6%) training groups increased their power output compared to the control (-3.5%) group, which had a slight decrease.

• With the uphill time trial, the uphill training group had a 4.4% increase in average power output over the 20 min, the flat training group had a -1.3% decrease (significantly less than the other two groups), and the control group a 4.0% increase.

• Power output was higher during the uphill than the flat TT both pre (4.4%) and post (6.4%) testing.

Putting It Together
The study was interesting in being one of the first to look at the specificity of interval training for performance on different terrains. The first obvious conclusion was that there is indeed a high level of specificity required for optimizing performance.

So if you are aiming for a flat time trial where the cadence tends to be high, you will see some improvement just doing any kind of interval training, but you will be better off concentrating on high cadence, flat intervals that replicate your actual race requirements.

Interestingly, the best performance in the flat TTs post-training came from flat intervals, despite the training load (greater power outputs) being higher with the uphill training. This reinforces the specificity of training rather than raw power.

Similarly, if you are focusing on climbing, with high muscular demands and low cadences, you need to climb and replicate those efforts.

Finally, if you are doing 20 min field tests to ascertain your functional threshold power (FTP), you may want to consider doing the testing in terrain that’s going to replicate your main goals and training, as your FTP results will differ depending on whether you are doing the test on a climb or on a flat course.

References
Nimmerichter A, Eston R, Bachl N, Williams C (2012) Effects of low and high cadence interval training on power output in flat and uphill cycling time-trials. Eur J Appl Physiol 112: 69-78.




About Stephen:
Stephen Cheung is a Canada Research Chair at Brock University, and has published over 60 scientific articles and book chapters dealing with the effects of thermal and hypoxic stress on human physiology and performance. Stephen’s Cutting Edge Cycling, a book on the science of cycling, is due out April 2012, and he can be reached for comments at stephen@pezcyclingnews.com .

 

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