Schlatter Family Site

Timex Bodylink®
Heart Rate Monitor
and
GPS Speed-Distance System

This article describes an interesting and useful device that I use while running -- the Timex Bodylink® System -- Digital Heart Rate Monitor, GPS Speed + Distance Sensor, Data Recorder, and Ironman Data Recorder Watch.  (NOTE:  "Bodylink" and "Ironman" are registered trademarks of the Timex Company; I will use these trademarked names several times in this article.)

This system consists of several devices that can be used in various combinations.  You wear these devices while exercising and the system measures some or all of:  time (total, lap, split); heart rate (max, average, heart rate in or out of specified zones); speed (pace, fastest pace, average pace); and distance (set to miles or km).  First, let's establish some guidelines for this article.

• I am not a fitness expert nor am I an expert in the topic of training, heart rate, VOmax (or whatever it is), training heart rate, and the like.  I do know that one goal of aerobic exercise is to get your heartbeat up to a "training rate" and hold it there for a period of time.
• I am a recreational runner and am not an expert on running.  At age 60, my average pace is 8 min 45 sec per mile -- not exactly world class.  I run five days a week, 3 - 6 miles per day.  For many years I ran 40 - 70 miles per week and completed three marathons in 3 hr 35 min - 3 hr 45 min (1988 and 1989 Marine Corps Marathon, 1990 Honolulu Marathon).
• I am writing this article to describe my experiences with the system and -- I hope -- to provide an introduction to the system for someone who may be planning to purchase the system.  This article is NOT intended to be a learned treatise on training heart rate, endurance training, or the Timex system.

Why the concern about heart rate while training?

One purpose of athletic training -- running, biking, kayaking, walking, and anything else that makes you breathe hard and makes your heart beat faster -- is to improve your endurance by putting stress on your heart and lungs -- your cardiovascular system.  Just as muscles grow stronger if you lift weights or otherwise use the muscles, your heart and lung become stronger if you make them work.

One measure of how hard you are making your heart work is heart rate -- how fast is your heart beating.  To improve cardiovascular conditioning, you want to get your heart rate up into the "training zone" and hold it there for a period of time. There is a formula that you use to determine your maximum heart rate; with that number, you then determine "training zones" -- as you elevate your heart rate, you got more and more training effect.  For detailed discussion of heart rates and training zones, check out these websites -- they will tell you more than I can.  There are likely other sites just as good -- these are some that I found.

• Understanding Your Training Heart Rate.  Good basic article, short.
• Heart Rate Training.  This site is sponsored by Polar, manufacturer of heart rate monitor systems for athletes.
• Heart Rate Monitors.  While this article discusses heart rate monitors, it also has an good discussion on training heart rate and heart rate zones.
• For more articles, use your favorite search engine and search for "training heart rate" or a similar phrase.

So -- one point of training is to get your heart rate up into the training zone -- into the area where you are improving your cardio-vascular well-being.  And the best way to monitor your heart rate is by using a heart rate monitor.  This is where the Timex Bodylink® System comes in.  For several months I had read about training heart rate and heart rate monitors so, in mid-2004, I took the plunge and purchased the entire Timex Bodylink® System.

The Timex Bodylink® System

Link to Timex Bodylink® site

Here is a link to the Timex website section on the Bodylink®.  Read their information -- it's complete and the photos are better than mine.      http://www.timex.com/bodylink/

(NOTE:  I will not put the ® mark next to the term "Bodylink" through the rest of this article -- just remember that "Bodylink" is a registered trademark.)

The whole thing

The entire Bodylink system consists of four devices and supporting software.  You do not need all four devices -- I'll address this point later.  Here is a photo of the entire Timex Bodylink System:

• Heart Rate Sensor (HRM) (Timex calls this the "Digital Heart Rate Sensor.")
• Speed + Distance Sensor (GPS)
• Watch/data recorder (watch) (Timex calls this the "Ironman Triathlon® Bodylink™ Performance Monitor.")
• Date recorder

How it works -- briefly

The watch is similar to other Timex watches such as their classic Ironman watch.  It tells time and has other functions -- time, countdown timer, alarm, and the like.  More important, though, the watch has built into it a tiny radio receiver that receives data from the HRM and the GPS; it displays and records this data to measure your heart rate, distance, speed, and time in various combinations.   The watch has a Summary Mode that stores the data from your workout.  After you stop your workout, you can put the watch in the Summary Mode and see your workout data.

The Heart Rate Monitor (more correctly, a heart rate sensor) straps around your chest just below your breasts.  Your heart beats because your brain sends electrical impulses through your nerves to your heart -- one impulse, one beat.  The HR sensor detects these tiny electrical impulses, thereby counting your heartbeats.  The HR sensor has a built-in radio transmitter that sends heart rate data to the watch and the data recorder.

  Front             Back 

The strap cinches around your chest and is adjustable in length.  On the back of the sensor are two elliptically-shaped areas with grooves -- these need to be moistened before you strap on the sensor.   The moisture causes the sensor to pick up the electrical impulses that cause your heart to beat -- some people moisten these sensors with water; I just lick them with my tongue.  The HR sensor stays turned on all the time, it does not have an on-off switch.

The GPS Speed-Distance Sensor straps onto your biceps by means of the elastic strap you see in the photo.  The GPS sensor proper is in a small plastic case.  In this photo you see the case -- the part with the labels -- inside its rubber outer shell.  You can remove the GPS sensor from the outer rubber shell -- this removes the rubber shell and the strap -- slide on the belt clip, and clip it to your waist band.  Note the elliptical object below the word "GPS" -- that's the on-off switch; between the switch and the word "GPS" is a tiny LED that tells you when the sensor is turned on and when it is locked onto the GPS satellites.  The sensor receives signals from the GPS satellites, thereby constantly monitoring your speed and distance traveled.  Not familiar with GPS -- Global Positioning System?  Read about it here.

The Data Recorder.  This little device clips onto your waistband and receives the data being transmitted by the HR sensor and the GPS sensor.  It records that data into a format that can be downloaded to your computer and displayed on the software that accompanies the data recorder.   Both devices record data from the HRM and GPS.  The watch displays the data on the face of the watch.  The data recorder does not have a display -- it records the data and dumps it to your computer via a USB cable.  You can use both the watch and the data recorder, or the watch or the data recorder alone.     If you use the watch alone, you can read your workout data from the watch in the Summary Mode and enter the data into your workout log.

Data Recorder: 
 front view                  rear view

Not very good photos -- but -- notice: on the front, a round button above the words "DATA RECORDER" -- that's the on-off switch.  There is a small LED above the switch to let you know the recorder is operating -- it flashes in a unique sequence when it's receiving data from only the HRM, or only the GPS, or both HRM and GPS.  On the rear view you see a row of four brass dots -- this is the connector to which you connect a USB  cable to download data from the recorder to your computer.

Data recorder with USB cable attached

Do I need it all?

You do not need all these devices at once. 

At a minimum, you need the watch -- after all, you do want to time your workout, right?

With the watch, you need either or both Heart Rate Monitor (sensor) and GPS Speed-Distance Sensor.  You can use the HRM by itself, the GPS by itself, or the two together.  The watch has a Configure Mode and a Display button that lets you change the data shown on the face of the watch while you work out.  Here is a photo of the watch during a workout -- note there are three lines of data displayed with the center line using larger digits than the other two.  By pressing the Display button, you can move the data around from line to line -- the charts below show what data will be displayed with each sensor, or with both sensors, and the charts show how you can change the way the data is displayed.

In this view, the top line shows the heart rate (158 beats per minute), the current pace (10 min 53 sec per mile), and the distance covered (1.104 miles)

• Heart Rate Sensor only.  This sensor sends to the watch and data recorder your heart rate.  As you run (swim, bike, canoe, whatever), the watch will display your current heart rate -- the watch display shows how fast your heart is beating right now.  The watch is also recording your peak heart rate.  With the HRM only, your watch can be set to display the following information in the following format.
  
   

  Heart Rate Split Time Lap Time

  Heart Rate Lap Time Split Time

  Heart Rate Split Time Lap Number

  Heart Rate Lap Time Lap Number

   

• GPS Sensor only.  This sensor receives location data from the GPS receivers and uses that data to measure how far you have traveled and how fast you are moving (your pace).  The watch and the data recorder aggregate this data to calculate your average pace, fastest pace, and total distance covered.  If you use only the GPS sensor, the watch can display one of these sets of data. 
   

  Lap Time Current Pace Distance

  Split Time Current Pace Distance

  Lap Time Avg Pace Distance

  Split Time Avg Pace Distance

  Split Time Avg Speed Distance

  Lap Time Avg Speed Distance

  Split Time Speed Distance

  Lap Time Current Speed Distance

  NOTE:  "Current Pace" or "Current Speed" is the pace or speed at which you are moving at that moment.  "Avg Pace" or "Avg Speed" means the average pace or speed from the time you started to right now.
   

• Both HRM and GPS Sensors.  If you use both the HRM and GPS sensors, the watch can display ten different sets of data as shown below. 
  
   

  Heart Rate Current Pace Distance	Heart Rate Avg Pace Distance	Heart Rate Current Speed Distance	Heart Rate Avg Speed Distance	Heart Rate Split Time Distance
  Heart Rate Current Speed Lap Time	Heart Rate Current Pace Lap Time	Heart Rate Current Speed Split Time	Heart Rate Current Pace Split Time	Heart Rate Lap Time Distance

So, how to use it?

I have the full system -- watch, data recorder, heart rate sensor, and GPS time-distance sensor.  Here are some important points: 

• The watch records data from the sensors ONLY when it is in the CHRONO mode.
• The watch and the data recorder record data from the GPS time-distance sensor only when you are moving.
• The data recorder records data only when it's turned on.
• This is important:  Do not put the watch in the CHRONO mode until you have turned on the sensors and the sensors have had a couple of minutes to start sending data to the watch.

This is what I do to get ready.

• Put on my shorts, socks, and shoes.  No shirt.
• Moisten the sensor elements on the back of the HR sensor and strap it around my chest.
• Put on my shirt.
• Pull the GPS time-distance sensor up on my left biceps.  Do not turn it on
• Put the watch on my left wrist.
• Clip the data recorder into the waistband of my shorts, in front of my left hip.  Do not turn on the data recorder.

Then, I go outside and do my warm-up stretches.  Before I start warming up I do this:

• Turn on the GPS time-distance sensor -- it needs a couple of minutes to get a fix on the GPS satellites.
• Warm up, stretch, walk up to where I start running.
• Put the watch in the CHRONO mode and reset it to zero out previous settings.  The watch will start to search for signals from the sensors and almost immediately will start to display your heart rate.  DO NOT START THE STOPWATCH.

As I start to run, I do this:

• Push the on-off switch on the data recorder and watch to see that the pilot light comes on.
• Push the start button on the watch to start the stopwatch
• Immediately start running.
• The watch and data recorder start recording data from the sensors.

Now, this is important.  Remember back up the page where I showed the various ways that the data can be displayed?  You can switch the data display and you can swap the data in the top line and the middle line (the one with the big digits) but you can do this only when the watch is in the CHRONO mode.  So, let's suppose you have the watch set up to show:

Heart Rate
Lap Time
Distance

But you want the heart rate to show in the big digits in the middle of the display.  Just push the "Display" button to switch the top and center lines.  Now the watch shows:

Lap Time
Heart Rate
Distance

When I am finished running, this is what I do:

• As I reach the point where I stop running, I reach down and turn off the data recorder, watching to see that the pilot light goes off.  This is important -- if you don't turn off the data recorder and stop running, it continues to record data and you will get corrupt data.

• Hit the stop button on the watch.

• After I cool down and go back inside, I sit at the computer, start the Timex software and connect the data recorder.  The software automatically downloads the data from the recorder.

The Timex Software

if you purchase the data recorder, it comes packaged with a mini-CD that contains the Timex Trainer® software.  This software stores your workout by date and displays it in various graphs and titles.  Here is a screen shot of one view of the data:

This graph shows data collected during a run.  The numbers along the top are MILES -- 1.1 mile, 2.5 miles, 3.9 miles.  Along the bottom are HRS:MINS -- 00:05, 00:35.  Note that I ran 3.9 miles in just over 35 minutes.  The numbers along the right side of the graph show my heart rate and the red line charts the heart rate throughout the run -- note that at 2.5 miles, approximately 00:22:30, my heart rate was slightly over 140.  The numbers along the left edge and the black wavy line plot my speed in MPH -- note that at the 15 minute mark I was running a little faster than 6 MPH.  I would like to see the software smooth out the pace line instead of showing a jiggly line for pace -- and I wish it would show the pace in MIN:SEC, not in MPH.

You can change the data you see on the screen.  Here is a screen shot of the various choices of data to display:

Read the instruction manual

The watch comes with a well-written, well-illustrated, and detailed instruction manual.  This article has only touched on the Timex Bodylink system -- you can find a lot more on the Timex site.  Here are a few random, closing thoughts.

How much does it cost?

The system is not inexpensive.  I have right at $300.00 invested in the system -- shop around for the best price.

Setting the watch

Here's a neat feature.  The GPS satellites transmit precise timing data synchronized to the atomic clocks at the U. S. Naval Observatory.  Every time you start the GPS speed-distance sensor and start the watch in CHRONO mode, the GPS sensor automatically sets the watch to this precise time.  Now, is that slick or what?

Who needs it?

For me -- a recreational runner and a gadget freak -- the system is a neat gadget and that's about it.  For the serious competitor -- amateur or professional -- or for the serious athlete who wants to sharpen his/her workouts, this system is quite valuable. 

Am I happy with the Timex Bodylink System?

Absolutely.

Lessons learned while using my Timex Bodylink® System

Here are some important lessons learned about using the Timex Bodylink® system.

The sequence in which you turn on the sensors and the watch is important -- but not fatal if you do it wrong.  Let me explain.

When you put the watch into the CHRONO mode, it searches for a signal from the sensors for one minute.  If you do not have one or both of the sensors turned on, the watch will not receive a signal and will stop searching.  If one or both sensors were not sending data, the watch will not display the missing data because it did not find the sensor during its one minute search.  If you know the sensor is turned on and want to make the watch search again, press and hold the DISPLAY button for more than two seconds, with the watch in the CHRONO mode, it will start searching again.

Here's why this is important.

• The heart rate sensor does not have an on-off switch -- it turns itself on when it starts seeing heart beat impulses.
• The GPS sensor has an on-off switch.  You must turn it on then it must get a fix on the GPS satellites before is starts sending data.
• Remember earlier in this article where there are three tables showing the information that the watch will display for the various combinations of sensors?   The watch must be receiving signals from the sensors to show the data associated with that sensor.

A couple of days ago, I strapped on the HR sensor, GPS sensor, and watch.  I have my watch set to show: heart rate, pace, split time.  I put the watch in the CHRONO mode; I warmed up and walked up to the point where I start running.  As I was walking to my start point, I turned on the GPS sensor.  When I started to run, I switched on the data recorder and pushed the START button to start the watch -- the watch would not display data from the GPS sensor -- no distance, no pace -- I thought something was wrong with the watch -- it would display only split time and heart rate because, during the first minute of searching (back when I was warming up), I did not have the GPS turned on, the watch did not find it, so, it would not display GPS data (speed, distance, pace).

When I got back home and downloaded data from the data recorder, all my data was there -- because I turned on the GPS sensor before turning on the data recorder, it picked up all data.  However, because I put the watch into the CHRONO mode several minutes before turning on the GPS sensor, the watch had already searched, found only the HRM signal, and it never did pick up the GPS signal.

After I got back home, I re-read the instructions and learned that all I needed to do was hold down the DISPLAY button for more than two seconds with the watch in the CHRONO mode and it would have searched again.

So, remember to have your sensors turned on, make certain the GPS sensor has locked onto the satellites, THEN put the watch into the CHRONO mode.

The watch must be in the CHRONO mode and must be receiving data for you to set the data display.

Recall the place back up on this page where I show three charts -- each of them shows what data the watch will display with the HRM only, GPS only, and with both sensors.  You cannot sit in your recliner and configure the watch to show the data.  To set the data that the watch displays:

1. Go outside so the GPS gets a clear shot at the sky.
2. Put on the HRM, the GPS, and the watch (or put on whichever sensor you have and the watch).
3. Turn on the GPS sensor and wait until the LED above the on-off switch starts blinking green, indicating it has a satellite fix.
4. Put the watch in the CHRONO mode.  The antenna icon will display, the watch will search for the sensor signal(s), and when it has locked onto the signal(s) from the sensor(s), it will show the data.
5. Press and release the DISPLAY button to cycle through the various display formats, stopping at the one you want.  Once you have the format in which you want to display the data, you can press the SET/FORMAT button to swap the upper line of data and the center line of data back and forth.
6. Now, the data display is set.  You can turn everything off and it will remain where you set it -- or you can now start using the system.

Changing the battery in the watch takes some special attention

Two points to remember when changing the battery in the watch.

1. You must remove at least one of the straps to change the watch battery.  Look at the back of the watch and you'll see how each strap has a lip that fits down over the metal back of the watch.  The straps are held in by the typical spring-loaded pins that must be removed to remove the strap.  I take off only one strap to replace the battery in my watch.  You need a very fine bladed flat-blade screwdriver to depress the spring-loaded pin to remove and to replace the strap.  It takes a bit of patience.
2. When you remove the metal back of the watch -- look carefully at how the plate is oriented.  Make a sketch if need be.  You must put this metal back plate back onto the watch in the same orientation as it was when you removed it -- otherwise -- the BEEP function on the watch will not work -- the watch will be silent -- no hourly chime, no alarm, no button beep, not a sound.

When you open the back of the watch to replace the battery, take a minute to study how the battery fits into the watch.  There's a thin metal strap over the battery that you must pry out with a thin knife blade or a very thin flat-blade screwdriver.   The watch takes a CR2025 battery.