Base exercise on speed or perceived intensity?

aurical84

Most of my exercise is from bicycling - either commuting to/from work or on the trainer (weekends and during bad weather, like today!). I use a cyclocomputer to track my speed and time.

Since my commute goes through the city it involves a lot of stopping and starting which slows my average speed considerably (10-11 mph avg) but increases the amount of effort I have to put in because I'm constantly losing any momentum I've gained. When I'm on my trainer, my average speed is *much* faster (~15 mph), but my effort is similar because I never have to stop.

When I enter exercise, MPF lists different levels of intensity for bicycling that are based on speed and effort (light/moderate/vigorous/etc). I feel that both my commute and time on the trainer are moderate to vigorous levels of effort, but the speed for my commute is in the "light" category.

To me it seems more accurate to log based on perceived intensity rather than the average speed since factors other than amount of effort can greatly impact your speed, but I don't want to undermine my weightloss by saying I've burned more calories than I really have... Thoughts?

Shuuma

Do you have a heart rate monitor? One with a chest strap? I would suggest strapping that on and seeing how many calories the HRM says you burn. I think it would be easier to track and more accurate than MFP's exercise base. My exercise is often way different than the database on MFP because of my size, heart rate, etc. (MFP is much higher most times.)

sheermomentum

How likely are you to sabotage yourself, either way?

If you are worried, choose the method that records the least amount of calories burned. The calorie calculators are not "gospel," anyway. So perhaps you could start with the lowest estimate, and see how you progress from there, making adjustments later if you want.

aurical84

I don't have a HRM and don't plan on getting one - maybe when I finish grad school and have a "real job"

I realize they are the best way to accurately track calories burned but that's why I was thinking that basing my workout on perceived intensity would be more accurate than the avg mph. I mean what the HRM is really doing is telling you how hard your body was actually working vs a hypothetical person of similar age/weight/gender.

For me moderate intensity means: elevated heart rate/respiration (to the point of making normal speech difficult) and sweating (even though its 30F with significant windchill) during activity, but no muscle soreness/fatigue afterward. This is what my cycling sessions generally are, though sometimes I'm sore after getting off the trainer because I always have a moderate to high resistance (i.e., always going 'up hill') vs my commute which is closer to interval training.

Shuuma

In lieu of a HRM, perhaps an app that tracks MPH would work? I use Zombies, RUN! and it tracks your mph along with calories burned based on that speed. It's not expensive and it's really fun. There are a lot of apps for smartphones that could maybe expand your options without breaking the bank.

AlwaysInMotion

Ah, fellow cyclist! Yeah, as you probably already know, trainer "speed" really doesn't track well to outdoor speed... there are too many variables at play like incline, resistance (wind, ground or roller tension), weight of you/bike/gear, and so on. Hence racer types shell out big bucks for watt meters. (It's all about the wattage.)

If you can't do the HRM thing (understandable), consider trying to estimate your intensity based on Rate of Perceived Exertion (RPE). You'll need to figure out your scale from 1-10 then plot where your commute would fall versus your usual trainer session. As long as you consistently estimate your RPE between both activities, you should be able to compare the two activities more accurately in terms of intensity.

For example, I know when I'm riding at moderate intensity (can talk) vs all-out max effort (about to toss my cookies) - and I can tell where I am on that scale when biking indoors, outdoors, or doing other cardio like running.

I'm guessing you're probably already familiar with RPE. Here are some links, just in case...
http://www.acefitness.org/acefit/healthy_living_fit_facts_content.aspx?itemid=48
http://www.cdc.gov/physicalactivity/everyone/measuring/exertion.html
http://www.acsm.org/docs/current-comments/perceivedexertion.pdf

AlwaysInMotion

In lieu of a HRM, perhaps an app that tracks MPH would work?

Sadly, when she's on a trainer (a stationary stand for her bike), she's not moving, so a GPS-based running/biking app that attempts to calculate MPH wouldn't help her (it would show 0 mph).

Shuuma

In lieu of a HRM, perhaps an app that tracks MPH would work?

Sadly, when she's on a trainer (a stationary stand for her bike), she's not moving, so a GPS-based running/biking app that attempts to calculate MPH wouldn't help her (it would show 0 mph).

You're right. I was just thinking about a baseline on her commute that could maybe help gauge a stationary workout. Sorry it's not a helpful thought!

AlwaysInMotion

Sadly, when she's on a trainer (a stationary stand for her bike), she's not moving, so a GPS-based running/biking app that attempts to calculate MPH wouldn't help her (it would show 0 mph).

You're right. I was just thinking about a baseline on her commute that could maybe help gauge a stationary workout. Sorry it's not a helpful thought!

You're advice isn't bad... actually, your HRM suggestion is likely the BEST suggestion for her situation. (It's a shame she can't swing one right now).