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Training with a Power Meter

By Troy Jacobson

Training with a power meter is a great way to take the guess work out of 'how hard' or 'how much' you're doing on the bike. Simply put, a weight lifter wouldn't do the bench press without knowing exactly how much weight is on the bar and how many sets and reps he or she is aiming to complete... or workload in a given workout.

In that same vein, a cyclist produces work in the measurable form of watts (power) when riding a bike. By understanding the relationship between workload and recovery, one can then train at certain intensities in a progression that will bring about a training adaptation. Sound confusing? It's not really, and I'm going to help you to understand more by sharing my power files with you.

Now that I've turned 40, I'm planning to get back into competition as a masters athlete. With limited time to train (sound familiar?!) due to family, work, travel, etc., I need to maximize my workouts each and every session. Along those same lines, I also need to be mindful of avoiding overtraining (I'm not 25 anymore) and injury. It's a good thing I found a qualified coach who can help me in my training process.

So, after several years of simply 'exercising' by doing steady state aerobic work just to stay in shape and in the attempt to avoid the middle age spare tire around the waistline, I started doing some intervals again recently. The first step when training with power is to discover your FTP or 'functional threshold power.'

Bascially, it's a 20 minute all-out effort at your highest sustainable output. You take your average power output in watts for that 20 minute, subtract 5% and that's your 'functional threshold'. This number comes in very handy both for retesting purposes (to see if you've improved) and for setting up your power training zones. Of course, the most accurate test is to actually compete in a 40k TT (or ride your brains out for 1 hour), but it's unreasonable to go this hard too often. In my test several weeks ago, my 20 minute result was found to yield 332 watts. That number is OK for a competitive 40 year old, but when you compare it to 440 watts that several of the grand Tour contenders are able to generate for up to 20-30 minutes in the mountains in late stages, it really tends to humble you! That, plus the fact that I weigh in at around 170 lbs at 6 ft tall and most of the guys in the pro peleton are between 140-155 lbs... which means their power to weight ratio is through the roof! Someone at a tri-camp in Tucson once asked me 'how do I climb Mt. Lemmon faster?' I quickly responded, matter of factly and without being politically correct, 'lose some weight.' Of course, it was a female athlete with a great sense of humor who asked me the question, but I was never able to live it down still to this day, even though my answer was factual!

Back to training with power. If you know your FTP, you can begin to develop training plans around that number. Every time you turn the pedals, you create work that is measured by the power meter and is recorded for analysis. It's really interesting because you can see where you are strong (on hills?) or weak (on the flats?). I, for example, have a rather efficient climbing technique, using the entire pedal stroke so my power numbers are really solid on uphills and into headwinds. When I'm on the flats or going downhill, my power numbers drop due to inefficiency in that downward stroke. This is something I now know I need to work on for race day.

power meter chartThe other great thing about training with power is that you can compare one day to the next. Since we all likely have standard routes we train on, we can record these rides in our software and measure one ride to the next and see where they differ. I have one of these rides that I did today. I call it my Rancho Time Trial Loop. The power file from my ride can be seen to the right, and here's how you interpret it. 

First of all, this is what I consider to be a 'tempo' ride, or at an intensity just near your AT (anaerobic threshold). For me, since my test for FTP yielded 332 Watts, my theoretical power at AT is around 316 Watts (or 332 less 5%). At this level of intensity, I'm hovering at or around my threshold which is a key intensity in which to boost your time trial race pace. 

By analyzing the power data, you'll see first that the entire workout took me about 1 hour (lunch break workout) with a short warm up followed by a series of five, 20-30 second 'pickups' where I maxed at at just over 900 watts. Then, I spun over to the starting point of my tempo ride, a rolling 7 mile stretch of road in Oro Valley, Ariz., with some steady climbs and some fast downhills. It was close to 100 degrees with a slight breeze and I was on my Litespeed Vortex road bike, so the goal wasn't speed necessary, but rather, power and effort. Unfortunately, the HR monitor was not working so that is not recorded.

For the entire ride, including the warm up, cooldown and soft pedaling in between, my average power was 228 watts with a cadence of around 88 rpms. I covered 20.23 miles and produced work equivalent to 814 kJ (kilo joules)... or burned approximately 814 calories during the ride. 

If I select the actual 'tempo' effort of around 7.57 miles, we'll discover that on this day, I averaged 24.53 mph at an average power output of 318 watts and an average cadence of 93 rpms for a total elapsed time of 18:16 minutes. Interesting, this same workout 2 weeks ago yielded a faster split of just over 25 mph, but a lower average power output. I believe this to be due in part to the fact I rode my Cervelo Sl-SLC with a Zipp 404 rear wheel... a more aerodynamic set up as compared to my Litespeed road bike with standard 32 spoke wheels. This strongly illustrates the need for aerodynamic gear and better positioning for all triathletes and time trialists... you go FASTER with less WORK. 

Once my TT was completed right in the proper power range for the workout (near my AT), I cooled down with my spin back home and then got back to work – after a quick shower, of course. 

So there you have it! A quality workout in an hour that was right on target based on my current fitness level and capabilities. Tomorrow (Wednesday), my plan is for an aerobic endurance ride where I'll average between 200-220 watts for about 1.5 hrs. This ride will allow for some recovery while also working on my aerobic engine and muscular endurance. I'll be careful not to push into that gray zone, so as to avoid overtraining and getting flat or injured. My next quality day will likely be in 2-4 days, depending on my schedule and how I'm feeling both on the bike and with my running. 

I hope you learned a little from this overview of my training and a glimpse behind the curtain. Please email me at if you have any questions related to training with power or if you'd like to see more articles similar to this one as I train for 2010. 

Train Smart and Train Safe,
Coach Troy

Coach Troy Jacobson, the founder of the Spinervals Cycling Video Series and a former pro triathlete, is the National Director of Endurance Training at LIFE TIME FITNESS. With over 80 fitness centers throughout North America, LIFE TIME FITNESS offers a full array of multisport training programs and services for the recreational and competitive triathlete. For more information, or