Friday, May 30, 2008

Product review: Polar RS800sd running computer

Well, at Four States Triathlon last week my Polar s625x crapped out on me. Besides a power meter for my bike, that was one of the best investments I've made in my training/racing. Despite all its advantages, it had many shortcomings. That's why when the Polar RS800sd came out last year, I was all excited because it kept all the things I liked about my 625 and fixed most of the things I didn't like. The downside was an exorbatant price tag. I had saved up for this for a while, but never was ready to pull the trigger. But when my 625 bit the dust last week, I figured why not. So I ordered one from Schlegel's bike shop and was ready to try it out.

A power meter on the bike is a large reason why I've been competitive at cycling this year despite my lack of training. A running computer is basically the equivalent: I can track my pace in real time, download all my data to TrainingPeaks software, and design my training and racing around estimates of lactate threshold, VO2max, etc. Very useful and effective. But as much as I loved my 625, I disliked many things:
1. Pace and distance would sometimes be way off and difficult to calibrate.
2. Pace/distance measurements fluctuated greatly depending on whether I was running an easy pace or a fast pace.
3. Altitude measurements always drifted to negative and were inaccurate
4. Pace was updated only in 5 second intervals so there was a pretty significant time lag.
5. The footpod was large and bulky
6. The footpod required a 2-3 sec start-up time which made it difficult to use in a triathlon since every single second counts in transition.
7. The wrist unit was like a small phone book on my wrist.

I've now had a handful of runs with my new RS800 and I have fallen in love with running all over again! Here is what I like about it so far, but I still have many more facets to discover as I use it more often.
1. Very slim on the wrist; fits like a normal watch.
2. Pace is updated in 1 sec. increments, so you can react without time lag.
3. Altitude feature doesn't drift anymore.
4. Pace/distance doesn't fluctuate that much when comparing my 8 min/mile pace to my 5:30 min/mile pace.
5. Footpod is small, compact, and lightweight.
6. Footpod turns on automatically. Now I can wear it in races and when I put my shoes on in T2, all I have to worry about is to start kicks in automatically.
7. Pace/distance is very easy to calibrate. You can even change it on the fly...if you run 1 exact mile, you can quickly go the menu and put the exact distance in and it will recalibrate automatically. After trying this out a few times, I now have it to where it's accurate to within 0.01 miles regardless of whether I'm on an easy jog or doing sprint intervals.
8. It has run cadence!! This is huge...I'll talk more about it later.
9. Works seamlessly with TrainingPeaks so that I can calculate rTSS, ATL, CTL, and TSB for running with ease.

There are a few things I don't like, namely that you can only display 3 lines of info on the screen at a time. There are lots of things I like to keep track of, including heart rate, pace, cadence, distance, lap split, and stopwatch split (total time). But I have figured a way around this. You can customize each screen, so what I will do for races is have one screen with pace/distance/cadence and another screen with HR/lap split/stopwatch split. You can easily toggle between the screens with the push of a button, so I'll mostly keep it on the pace screen and flip to the HR screen when I want. Very easy to do during a race.

For biomechanical reasons that I won't get into here, it is often optimal (for most body types) to run with a cadence of 90 or so, and nearly all elite runners do this. I've always tried to stay around this number, but have had to rely on sporadic spot checks: I count my right arm swings for 20 seconds and multiply by 3 to get the number of same-sided steps per minute (my cadence). Now, all I have to do is look down and see where I am. Turns out I am really good about running at a cadence of 90 most of the time. But what I found was that during my hard, speedwork, I actually run with too high of cadence. Your overall speed is an interaction between stride length and cadence such that speed = stide length x cadence. If you increase your cadence and keep stride constant, speed increases, or vice versa. But since a cadence of 90 is generally preferred, this means the primary way to change speed is to manipulate stride length. If I run a marathon, I try to run a cadence of 90 with shorter stride lengths (too long of stride lenghts, and too much speed, means I'll bonk before I finish). If I run a 5K, I *should* run a cadence of 90 but increase stride length to the maximum that I can hold for that distance. What I found out after only one session with my RS800 was that during my speed work, I was increasing my cadence too much and not lengthening my stride enough. Once I identified this, I slowed my cadence back down to 90 and increased stride length by adjusting my arm positioning (I've already rambled too long, so won't go into how to do this, but trust me, you can manipulate stride length purely by adjusting arm carry). Once I made the adjustment of doing my speedwork with a cadence of 90 but longer stride length, my overall speed was way higher than I'd been running for my past interval sessions!! Eureka! Analyzing training data to improve performance at its finest.

Overall, I'm very happy with the purchase. The price tag is just absolutely ridiculous, but in my opinion, if you are going to drop a lot of money, it's best to drop it on things that help you train more than flashy items used for racing only. The logic is that training is what really makes you faster. This was definitely a good investment for training. I'll give it its first race performance this weekend at the Rt. 66 Sprint and Rt. 66 Oly. I'm still not in great running shape for the year yet, but I'm anxious to see how/if it helps me during the 5K on the sprint and the 10K for the Oly. I'll be watching cadence and pace like a hawk to push myself to the limit that I can withstand.

1 comment:

Anonymous said...


Great write up. I just purchased the running version with pod and had a question about the bike accessories. They sell a cadence and a speed accessory, yet I have noticed a "power" accessory that seems to track the same data and then some (but is much more expensive). I would like to use this for Tri training / races. Just not sure what the optimal equipment would be on the cycle side. Let me know your thoughts on the best compatible equipment for the bike.