Most avid runners have their 'song': "Chariots of Fire", "Don't Stop Believing", "Freefalling". But is it the terribly clichéd lyrics or the beat itself that provides inspiration? The Yamaha BodiBeat is part MP3 player, part heart-rate monitor, and part metronome for your workout. The gadget serves as a personal trainer and DJ by selecting songs with the beats per minute necessary to keep you going. Armed with a setlist of Journey and Sublime, and in search of a nine-minute mile, we tested the device on the hills of San Francisco.

The system comes packaged with a arm strap, USB charger (no wall charger), software (about which more below) and a set of headphones with a small clip intended for your ear lobe, to monitor heart rate -- it's surprisingly comfortable. The device's screen is small, and its buttons are awkward and not well marked. The user guide gets you up and running quickly, though many of the more sophisticated options are buried a bit.

Before uploading our own tunes, we took the system on a test run using the songs that come preloaded. The two most basic modes of operation are "free workout" and "walk or jog fitness." Free workout lets you move at whatever pace you want while the system picks songs based on your current heart rate. "Jog or walk fitness" takes into account your age, weight, and height (based on information you enter) and selects a song to get you moving. For our trial, we selected "free workout," put the dog on a leash, and headed towards the bridge.

The included mix is something between techno and what you'd expect to hear in a Mario Brothers game circa 1986. The dog's penchant for stopping along the route offered ample opportunity for the system to adjust to my heart rate. Immediately, I found myself running to the electronic beat. An underlying drum beat in most the songs seemed to hit right with my stride. My big complaint was that the system seemed to change songs every few seconds. Right when I'd actually start to enjoy a song and settle in, the tune would change. I also found myself looking down awkwardly at the device to check my heart rate (which isn't displayed) and the beats per minute of the tune. The next generation of this device should perhaps audibly provide that data each time it changes songs.

The included software easily allows you to post-process your workout, looking at distance, pace, and heart rate. Each workout is nicely logged, allowing weekly summaries and analysis. In a 16-minute jog I went through 36 different "songs," many repeating and playing for just seconds. The system seemed to overestimate the distance I traveled based on a predicted "stride length," which you can manually adjust but which is hardly a sophisticated method. I also found myself questioning the accuracy of the heart rate monitor, but a quick test run using my finger showed it was accurate to within a few beats per minute.

Determined to ditch the techno beats, I dropped my personal selection of Sublime and Journey onto the system. This was quite easy. Perhaps one of the more interesting features is the display of the beats per minute of any song in your library. Who would've known that "Lovin' Touchin' Squeezin'" is the slowest track on Journey's Greatest Hits?

The second free workout began with a bit of Sublime: "Summertime," which seemed like an excellent choice for a warmup. With my heart rate up to 137 BPM, Journey then piped in with "I Can't Fight This Feeling Anymore." All was going well when Sublime's "Caress Me Down" interrupted and toggled back and forth with some of the techno songs (which I thought I had deleted). Despite having more than 20 songs in my playlist, and my heart rate ranging, "Caress Me Down" continued to cut in over the next seven minutes but never once got past the two-minute mark. "Wrong Way" started up for ten seconds on a quick sprint but then it was back to "Caressing" before cooling down with more "Summer Time."

A device that can "hand-pick" songs seems like a fantastic idea, but the constant changing, and lack of audible updates, had me flipping to normal play mode just so I could get through an entire version of "Faithfully." The device functions well as a heart-rate monitor and standard MP3 player, but with only 512 MB of memory, those two functions hardly justify the price tag of $299.95. For those unable to keep a steady pace, the included techno beats do the best job of keeping you consistent -- assuming you can tolerate the music.

yamaha.com/bodibeat/