PowerCranks - do they make you a better cyclist?

There was a study that came out recently in regards to PowerCranks (abstracts below) and it created some very interesting threads on the SlowTwitch forum. Actually, PowerCranks have always been a lightning rod on the forum with lively debates on whether or not they can make you a faster cyclist. I had read about them a few years ago and after my 2008 season, I decided to try to find a set on eBay. They are not cheap, but I managed to get a used pair for around $400 in August of 2008. I started using them in September on the trainer and gradually built up to where I could ride on the roads for 3+ hours with big hills. Now I use them primarily on my road bike in the off-season and occasionally mix in a ride in the season. It has now been 2.5 years or so and with this study coming out, I wanted to reflect a bit on whether these PowerCranks have made a difference. A little n=1 analysis of my own, if you will. I also started using a power meter at approximately the same time, so I have a decent quantitative assessment of my progress, including some tests and rough guesses at my FTP on the bike and some decent race comparisons.

In February of 2008, I had a threshold test done on a CompuTrainer and they put my FTP at 240 watts at the time. Given that I weighed about 78 kg at the time, my power/weight ratio was ~3.08, not exactly world class. In February of 2010, I was tested again on a CompuTrainer and my FTP at the time was estimated at 280 watts. My weight at that time was 72.3 kg so my power/weight ratio was ~3.83. Getting better. By that time, I got pretty good at judging where my approximate FTP was based on just riding with the power meter, and this seemed a touch low. The next interesting data point was early June of 2010, which was right after a BIG month of riding and IM training and starting to taper for IM Coeur d’Alene. I did a 10 mile TT and averaged 328 watts. This was outside on my tri bike (incidentally, the previous 2 tests were on tri bikes with the one in 2/10 being on the same bike). 328 watts over 23+ minutes equates to about an FTP of 310 watts. And I weighed about 72 kg at the time, so my power/weight ratio was 4.3. Now we’re getting somewhere.

If you look at a race I did in ’08 and ’09 (unfortunately I didn’t do it in ’10), my bike split went from 2:40 to 2:28. I didn’t have the PowerTap for the race in ’08, so I don’t know what power improvement there was to cause this improvement. I was probably also lighter in ’09, but my guess is, the power improvement made the biggest difference in the time on the bike. I was using PowerCranks a lot starting after the ’08 race through the off-season and into pre-season for 2009. Interestingly, my run split went from 1:39 to 1:31 over that same time, likely a byproduct of being stronger on the bike, but perhaps also from some work on the PowerCranks?

So, over the time I’ve been using PowerCranks in general, I’ve had an increase in FTP of about 70 watts or about 30% of where it was initially in roughly 2 years. However, PowerCranks are not the only thing that changed. Over that same time, I also started doing different kinds of bike workouts. A main addition to my workout repertoire was mixing in some strength. Hard intervals on the bike on my trainer in my garage (“man-cave” or “pain-cave”) mixed with strength exercises, including squats, jumps, step-ups with weights, etc. In addition, I did some work in the gym on the leg press machine, etc. Out on the roads, I also did a lot more work at threshold on the bike. I was used to this in running, but needed to work a lot harder on the bike.

And I was doing long hill repeats on the weekend (e.g. 5x the climb out of the confluence) to build more strength. So, there are a lot of variables here.

If you look at the two studies, they try to isolate out the PowerCranks as the independent variable, but that’s tough. In the Luttrell study (which is a little old now), they found an improvement in efficiency and reduction in O2 consumption at a given intensity. In the Sperlich study, they found no significant difference in any of the measurements. I haven’t read the entire studies so I don’t know what else may be different, but obviously, the Sperlich study suggests PowerCranks (or separating the cranks so you are forced to pedal each leg independently) will not make you a better cyclist - or at least not PowerCranks alone. In my case, far too many variables changed to know what made the largest contribution. My feeling is that the PowerCranks may have been part of the overall puzzle, for both the bike and the run, but the take-home message for me is that there is no substitute for some good, old-fashioned hard work.

Newest study:

Eur J Appl Physiol. 2010 Dec 31. [Epub ahead of print]

The effects of 6-week-decoupled bi-pedal cycling on submaximal and high intensity performance in competitive cyclists and triathletes.

Sperlich B, Zelle S, Kleinöder H, Lochmann M, Zinner C, Holmberg HC, Mester J.

Institute of Training Science and Sport Informatics, German Sport University Cologne, Am Sportpark Müngersdorf, 50933, Cologne, Germany, sperlich@dshs-koeln.de.

Abstract

Aim of this work was to examine the effects of decoupled two-legged cycling on (1) submaximal and maximal oxygen uptake, (2) power output at 4 mmol L(-1) blood lactate concentration, (3) mean and peak power output during high intensity cycling (30 s sprint) and (4) isometric and dynamic force production of the knee extensor and flexor muscles. 18 highly trained male competitive male cyclists and triathletes (age 24 ± 3 years; body height 179 ± 11 cm; body mass 78 ± 8 kg; peak oxygen uptake 5,070 ± 680 mL min(-1)) were equally randomized to exercise on a stationary cycle equipped either with decoupled or with traditional crank system. The intervention involved 1 h training sessions, 5 times per week for 6 weeks at a heart rate corresponding to 70% of VO(2peak). VO(2) at 100, 140, 180, 220 and 260 and power output at 4 mmol L(-1) blood lactate were determined during an incremental test. VO(2peak) was recorded during a ramp protocol. Mean and peak power output were assessed during a 30 s cycle sprint. The maximal voluntary isometric strength of the quadriceps and biceps femoris muscles was obtained using a training machine equipped with a force sensor. No differences were observed between the groups for changes in any variable (P = 0.15-0.90; effect size = 0.00-0.30). Our results demonstrate that a 6 week (30 sessions) training block using decoupled crank systems does not result in changes in any physiological or performance variables in highly trained competitive cyclists.

First study:

J Strength Cond Res. 2003 Nov;17(4):785-91.

Effects of short-term training using powercranks on cardiovascular fitness and cycling efficiency.

Luttrell MD, Potteiger JA.

Department of Health, Sport and Exercise Science, University of Kansas, Lawrence 66045, USA.

Abstract

Powercranks use a specially designed clutch to promote independent pedal work by each leg during cycling. We examined the effects of 6 wk of training on cyclists using Powercranks (n=6) or normal cranks (n=6) on maximal oxygen consumption (VO2max) and anaerobic threshold (AT) during a graded exercise test (GXT), and heart rate (HR), oxygen consumption (VO2), respiratory exchange ration (RER), and gross efficiency (GE) during a 1-hour submaximal ride at a constant load. Subjects trained at 70% of VO2max for 1 h.d(-1), 3 d.wk(-1), for 6 weeks. The GXT and 1-hour submaximal ride were performed using normal cranks pretraining and posttraining. The 1-hour submaximal ride was performed at an intensity equal to approximately 69% of pretraining VO2max with VO2, RER, GE, and HR determined at 15-minute intervals during the ride. No differences were observed between or within groups for VO2max or AT during the GXT. The Powercranks group had significantly higher GE values than the normal cranks group (23.6 +/- 1.3% versus 21.3 +/- 1.7%, and 23.9 +/- 1.4% versus 21.0 +/- 1.9% at 45 and 60 min, respectively), and significantly lower HR at 30, 45, and 60 minutes and VO2 at 45 and 60 minutes during the 1-hour submaximal ride posttraining. It appears that 6 weeks of training with Powercranks induced physiological adaptations that reduced energy expenditure during a 1-hour submaximal ride.