iPhone or Garmin?

If you're thinking about starting to use a GPS to track your runs you've probably heard about Garmin's wrist-watch type GPS units and some of the new iPhone applications. Both options are great, but there are some things you should consider before you spend your money.

Ease of use while running

If you want to use your GPS to monitor pace or other data while running it's a lot easier to glance at your wrist than it is to look at your iPhone. iPhone applications need to conserve battery life. They also need to make sure that jostling in a pocket or while on a run doesn't become accidental keystroke input. So they dim the display and lock the input. A Garmin GPS won't dim the display or lock the input. The wristwatch format is much better for use while running.

Battery life

Using the GPS feature and display on an iPhone uses the battery very quickly. Most of the iPhone GPS applications claim to get 3-4 hours of battery life. I did a 15 mile run today with a fully charged iPhone. By the time I got home the battery was nearly dead. My Garmin ForeRunner 305 recorded data for more than 10 hours on an ultra-marathon. If you "go long" you'll want battery life that goes as long as you do.

Accessories

Garmin fitness GPS devices can be used with accessories including a heart rate monitor, a bicycle cadence monitor, and a footpod for indoor use. I haven't seen any fitness accessories for the iPhone yet.

Features

The iPhone applications are getting more sophisticated, but are far behind Garmin. I set up the display screens on my Garmin 305 like this:

Main 1: Default view, most useful things
Distance
Average Pace
Time

Main 2: Lap pace, when you need to kick it up click lap and then watch pace improve
Lap Pace
Lap Distance
Average Pace
Pace Zone (to get you used to pace zones for when you use them in workouts)

Running: It's all about heart rate zones, right?
HR Zone
Heart rate
Average HR
Heading (in case you're not sure which way you're going, it's a GPS, after all)

Defined workouts

I haven't seen any iPhone apps that allow you to create pre-defined workouts to guide your runs. The ForeRunner has a special display for work-outs. I use heart rate zone targets mixed with pace/distance targets for interval training, things like Run 1 mile at "Fast Run" pace, then run 1/2 mile in HR Zone 3, repeat three times. For recovery runs I use a HR zone stair step (5 minutes in zone 1, 12 minutes in zone 2, 5 minutes in zone 3, 13 minutes in zone 2, 5 minutes in zone 1). The Garmin will guide you through the workout and alert you with a beep when you're out of range.

Training log Software

The iPhone apps work with web-based training log applications. Map my Run has some nice features and their iPhone application works very well. Garmin GPS devices come with Garmin Training Center and also work with motionbased, garmin connect, and many of the web-based applications. In addition, Garmin devices can be used with SportTracks or Ascent. SportTracks is the best software trainng log, hands down.

Price

If you already own an iPhone 3G you're in luck. MapMyRun.com and their iMapMyRun iPhone app are both free (for the basic service). You can get started using a GPS to track your runs by downloading the iPhone app and signing up for the service. If you don't own an iPhone 3G and are serious about logging your training get a Garmin.

The bottom line

I'm a big fan of the iPhone and am in most cases a strong proponent of web-based software. I'm also serious about my training and want to take advantage of of the full capabilities of the GPS technology. For me, there's no question, Garmin is much better than the iPhone for GPS Running. The iPhone advantage in price (if you already own one) is an important consideration.