Power Meters

Please check out Scott McMillan (Factor 9 coaching) and his comments on power meters. All very good points.

http://scottkmcmillan.wordpress.com/

In response and support of some of Scott's comments:

Using the SRM has definately changed my training. For instance, by training in proper wattage zones similar to HR in running, I have been able to objectively increase my power for various distances. Knowing your zone 4 power ceiling, similar to your AeT in running is vital or don't waste the money buying a meter. In fact, I spent less than 5% of my intervals above zone 4 but had specific workouts designed to increase my strength in power zone 4 (1/2 IM power) and zone 3 (IM power..these are arbitrary and only my interpretations of my zones and they will vary with individuals). Now, major benefit to my SRM is the ability to monitor power of each leg doing single leg intervals. I immediately realized a 20 watt difference. My single leg intervals allowed me to target power with my right leg, which felt a bit easier, and a bit harder with my left leg. Eventually after about 8 weeks my left leg "caught up" with the right and I found very similar power output for both legs. This also leads to less injury risk.

The SRM wires are thin and somewhat friable, which I find annoying, esp when a wire stops functioning the week of a race. The Ergomo wires are far more durable. However, SRM has approached their problem by developing a wireless power meter, using the crank as before.

It's tempting to become a data freak on these. I got caught up in this for the first several months and then realized its somewhat of a waste of time and effort. My graphs the first several months would look like a saber-tooth, very choppy with significant variances in power during a single interval. Now my power curve is very mildly undulating, almost a flat line graph during my interval. This tells me that I have developed the ability to maintain a consistent power output during an interval or race, much of which is due to monitoring my output during the interval frequently, and equalizing my leg strength.

I now only look at average and normal power for a specific workout and my TT intervals, and compare week to week. Comparison is someone a misnomer because I train in power zones without trying to steadily increase my output week to week. In fact, after Germany in June, and 2 weeks prior to Western Australia, my power z4 cap had only increased 10 watts. This is a minimal change. However, I could sustain the z4 power at just above 3oo watts for an entire 56 mile TT. 1 month after Germany, I could only sustain this for 50 minutes. As an athlete, you DON'T have to push the envelope each week or block of training. By far...more consistent results can be achieved by consistency in training, not always believing you have to obtain higher and higher power as you progress through the season, but increasing the duration at which you can hold a specific sub threshold power.

The most important difference I 've seen in changing to power is this. I learned how much my HR was deceiving me. For instance, I biked Clearwater 70.3 at an average 310 watts and my HR never rose above zone 2 for more than 30 miles. When it steadily rose in the tailwinds, I allowed it to creep up into HR zone 4, but at that point, I was competing hard and confident I could push into low power zone 5 for nearly an hour, then back down to near the end and take some rest.
In training, if you follow my blog, 1 month after Germany, I was doing 45 min TT intervals at 300-310 watts and the final 20 minutes I would rise into HR zone 4, the final few min, HR zone 5 and power around 400. In fact, I reached my max HR on the bike (max meaning the highest HR I've ever recorded on the bike) during one of these "power zone 4" intervals.
The relevance? By the end of the summer, 12 weeks out from Germany, I was doing the same intervals, under the same conditions, with far different results.
Exact same course and total distance
Interval beginning similar point in the ride, and on a similar volume week
Exact same gear ratio (54/11-12)
Same cadence
Very similar conditions

However, my HR only maxed out in mid zone 2 at the end of the interval. This is a sure sign of proper training and building. Hence, I continued to feel stronger right through my taper to IMWA. I say this because if I trained only per HR data, I would have likely pushed my HR into Z3 or 4 on some of these intervals and this would have been way above my intended bike power zone 4 goal. I would have likely have generated power numbers 350 or more...and hence burnt myself out over several weeks. In fact, doing multiple power zone 4 intervals going into my taper, my HR would peak at just above zone 1. With no power meter, I would typically push my HR into zone 4. I dont know what my power was when I did this as I had no monitor then, but I am certain I was way into zone 5 power due to my cardiac fitness, and likely was pushing watts far to high in the weeks going into my races.

So, this is why I now use specific gear ratios and cadence for those without power meters and the HR is secondary. HR use is important to know your Aerobic and Anaerobic caps so its always good to stay in your proper HR zone and not climb too high. However, just arbitrarily pushing to your HR into a pre determined zone may be very high watts so you have to rely on how your legs feel, and really get to know the feeling of fatigue when using HR alone. In my mind, and in retrospect, my 2 best bike splits ever in my 8 IM races were the two races I had no HR monitor. CDA 2004 and IMWA 2007. In CDA, I strictly pushed based on a 'feeling' of comfort, and in IMWA I knew how much power to push at. Of course in my report, this power was causing fatigue in my quads on the bike (260+ watts). However, I trusted my predetermined numbers from training and went with my power over the feeling in my legs. This worked out for me but I dont necessarily recommend this for most age groupers. Consider I did 60 interval workouts in an 18 week period leading up to IMWA. So, I believe my legs could handle such stress, and they did ( in retrospect...I was still a bit worried coming into T2)

Bottom line: Use of a power meter will in most cases improve your performance. Many times at USAT Nationals, on a hilly course, my power would climb above 310, my z4 cap. I would slow down, and get passed by many people on the hills...age groupers probably putting out 500 watts as they blew past me on the hills. However, when cresting the hill at 8mph at my power cap, it was very soon after I would pass them all back holding 310 watts on the flats, at 25-27 mph and never seeing them again. So, the use of power is very important to know YOUR limit. This is how you improve and race well. Knowing your limit and using this limit to grow steadily and consistently through the season. Training with HR zones on the bike in the absence of a power meter is still beneficial, esp once zones are established using field tests on the bike. Now, as you become more fit, you need to be aware of the potential significant HR drops that come with fitness on the bike. Mine for instance, dropped a full zone downward after 12 weeks of specific training. On that same note, my HR zones limits on my run only drop 2-3 beats over similar periods, a significant differnce compared to the 8-10 beat drop I experience on the bike as I get more fit. That being said, just be aware that your cap of HR zone 4 on the bike may and likely will drift to a lower number as you get fit on the bike. If ignored, then using the same HR cap at your threshold will lead to training above your newly esablished threshold as fitness progresses. Solutions to this are possible. Simply be aware and re-establish your TT thresholds throughout your season, like initially, then at 8 weeks, and 16 weeks depending on the length of the season. If your legs feel great, your able to use bigger gear, more speed, etc. , but your HR is several beats lower upon subsequent field tests, then you've experienced increase fitness and can adjust your new HR zones based on this. However, of course keep in mind lower HR values during interval field tests dont always mean better fitness. If you are not putting out more power, (better power subjectively measured secondarily by "feeling great", more speed, bigger gear ratio ) and instead feel a bit fatigued, less speed than usual, trouble maintaining similar gear used in past tests...and your HR is lower, then this a sign of over training and some needed rest. These things are difficult to quantitate at times and come with repeated self evaluation over time. Now, with a power meter, these values become much more simplfied. If I do the same interval set week after week, and my power in the 12th week is lower than typical, and my HR is also lower, I need to rest. The inability to push your HR up to your threshold and subsequent lower wattage output is a sure sign of over training. Now, if your HR is lower than usual after your second field test under similar conditions, and yet your able to generate the same or slightly higher ave power, than this is a positive sign that fitness is increasing.

And yes, I do look down at my monitor frequently, but my head position doesnt change as I have my monitor set up between my extensions to I just glance down with my eyes. Doing this every 15 min or so helps me, esp in races like IMWA, where I was at times at too high power average, so I would intentionally back off to bring my ave watts back down to a window (260-270) that I knew I could hold for the entire 180k.

Good blog Scott, great info and alot to think about before buying a pricey monitor.