Pedalling faster is easier

We found out earlier in the show how much energy cyclists use, but how fast should you pedal? Dan Gordon, from Anglia Ruskin University, explained to Chris Smith why pedalling faster is actually easier, with help from cyclists Kate Lamble and Anglia Ruskin student Karin...

Dan - So, the next trick is we're going to look at the effects of cadence. This understanding that high cadences are theoretically more efficient and we know particularly the climbers like to use high cadences because it's much easy in terms of getting the force through the pedal when you're going up a steeper gradient.

Chris - Why is it better to turn the pedals faster when you're under those conditions then, which is what high cadence effectively means, doesn't it?

Dan - Absolutely. It's a great question. The key comes down to the amount of force that has to be produced. So, if you imagine that you're doing this slowly but we're still working at the same wattage then you're having to use more muscle or muscle mass to produce that force. But if we're doing it at a higher cadence but maintaining this same relative wattage then actually, the metabolic cost, the energy cost to the muscle is lower. Actually, most of the work then comes from what we call 'neural recruitment', how quickly you can get those muscles to lengthen and shorten.

Chris - So, what should we see here and what are you going to ask the two of them to do?

Dan - So, I'm going to ask them both to now cycle again, with the same relative workload, but this time, at 110 revs per minute. So, we're going here, 40 revs per minute higher than they were cycling before. So, this is those cadences that we see, as I say, things like team time trials and the elite climbers will use these kind of cadences.

So, what we want them to do is try and maintain this and it would be very interesting to see what they start to report because they're not used to these cadences. I mean, Karin doesn't ride at these cadences either, but we know that athletes who train at these cadences start to become very economical and start to actually find them much easier to maintain than those lower cadences.

Chris - It just seems strange to think that going faster is easier.

Dan - It just seems counterintuitive, doesn't it? But it's certainly this idea that if you imagine the amount of time that pedal goes round, so the longer it takes for a pedal to around, you're using more energy. In the demonstration earlier on where we saw these heart rates starting to rise, it would be nice to see if let's say with Kate, the heart rate doesn't rise quite so quickly. That would be the anticipation.

Chris - Okay, should we give it a go?

Dan - We're going to start Karin off first. So, Karin starts pedalling and I'm going to put the resistance on. So, up goes the resistance, 175. So, Karin is now at the required cadence.

Chris - How does it feel, Karin? Is it easier?

Karin - No.  I cannot say it is. Actually, it's not as tough as I thought it would be.

Chris - So, it is in that respect. It is a bit easier.

Karin - Mentally, yes.

Chris - So, we're loading up Kate. You're aiming for 110?

Kate - I'm not sure I can get.

Chris - 110, there you go. And so, this would be about 40 km an hour, Dan, up a hill.

Dan - Well, no. Up the hill, they would be going at a slower speed of course. The thing we have to take into account is that they're using different gearings when they go up a mountain. So, they can't be pushing the bigger gears, but it's the equivalent you may see for example in a team time trial.

Chris - How are you feeling, Kate?

Kate - Tired. I mean, Nairo Quintana who's the climber was my hero last year so I'm trying to channel a tiny Columbian man but it's not really working.

Chris - Do you expect them to go much longer?

Dan - No and partly because they're not used to this kind of work. Again, as we talked about earlier on, the way in which the muscle adapts training, so does the central nervous system. And so, the ability to recruit the muscle. They're doing remarkably well for this same workload.

Chris - Are you nearly done?

Kate - I'm really done.

Chris - Okay, so you're done. How are you doing Karin as the trained cyclist?

Karin - I'm sure you could forget the word 'trained' at the moment. I feells harder.

Chris - This is kind of rush hour in Cambridge, you're doing here.

Karin - This is worse than rush hour in Cambridge. Rush hour in Cambridge is just watching the other cars. 

Chris - Kate is now begging for her heart rate to be measured. What do you expect? It feels like it's going...

Kate - About 4 million.

Chris - 176. So, it's up a little tiny bit.

Dan - So, it's up a little bit, but not much different to what Kate was experiencing when she was doing the lower cadences. So, let's try Karin who's breathing very hard over the far side.

Chris - You've given up.

Kate - I can't manage 110, I was just - you can see the number sort of sneaking down into the 90s and realise that you're not going to be able to get them up again.

Chris - Karin is still going and we're just registering the heart rate of - wow, 110. So, that's actually lower than when she was at her peak which is exactly what she said. So, it does work.

Dan -  It does work although it looks and Karin feels like it's really hurting but actually, physiologically, she's using less energy.

Chris - Should we let her off?

Dan - I think we should.

Chris - So, while they go and die quietly over there, what about at the level of the muscle? When you're doing this, when they're working out like this, when you're working very, very fast, does this also affect the blood flow through the muscle because if your muscle is not spending as long contracting, does this mean the blood vessels are open for longer so more blood can flow in and out?

Dan - Absolutely. So, if you imagine that as the blood's going through, every time the muscle contracts, if it's at a slow rate, it's going to push down onto the arteries. It's also going to push onto the vein. So, if you're going at a slower cadence, those muscles can press in the arteries a little bit. Not completely but they can press it so they make it harder to push the blood through so we're having to use the high blood pressure. Because the cadence is higher, we're not maintaining it for so long, so as a result, we have lower blood pressure response, we get the oxygenated blood to the muscle more efficiently, and we're also able to get that carbon dioxide away as well.