Our inventions are wont to be pretty toys, which distract our attention from serious things. They are but improved means to an unimproved end.
Henry David Thoreau
I guess when Og, the cave man, was running from the sabre toothed tiger, the last thing on his mind was "how far have I gone, what is my heart rate, have I hit my anaerobic threshold yet?" Since there aren't all that many sabre toothed tigers anymore, most running (or biking or kayaking or hiking) is done for exercise and recreation - it sure is fun to carry toys.
I've had a Garmin 60cs GPS unit for several years and use it all the time for hiking, biking and kayaking. I did a 3 day bike ride across southern Pennsylvania with the Garmin on my handlebars and no printed maps or cue sheets. OK, I did print out paper maps and take them along - but they never left my panniers.
My latest toy is a Garmin Forerunner 305, which is basically a GPS wrist watch with heart rate monitor built in. My excuse for buying it, besides the $50 rebate, was that my wife is a runner and the genius of the Forerunner is really for runners: it uses GPS to allow them to know how far they ran and how fast they went, without having to go out and drive the course. I also figured it would be handy for kayaking, as the 60cs is hard to mount somewhere on a kayak where it will be visible without getting in harms way. OK, and I wanted a new toy.
The Training Center software that comes with the Forerunner lets you do some cool analysis, but you can't print or save graphics or statistics - you have to use the MotionBased web site to do that. They are trying to sell you a $8/month subscription to MotionBased, but for free you can still do some fun things. See my 17 mile bike ride here and right below is a summary heart rate graph from that ride.
That ride is two 8.5 mile "laps" around and through some neighborhoods in Ashton, MD. The first lap I did with my wife, who can run me into the ground but doesn't do that much biking and had already hiked 7 miles that am. You can see my heart rate averaged in the 120s for the first lap, but after Carole dropped off I first really accelerated to pass some other cyclists and then tried to push hard for the full lap. That got my heart rate up more into the 140s and my average speed was a good bit higher, too.
Now, before all these toys I would just go for a bike ride or kayak paddle or hike and feel good after-wards. Now, I can look in detail at the exercise and feel bad that I didn't push harder...