CRANE SPORTS     MD41819   Strapless  Heart Rate Monitor.

 Fitness Watch / Pacemaker

Full view of  MD41819 heart rate monitorI  am attempting to get fit and saw this watch at Aldi for a good price. After spending a few hours with it I began to realize just how much work had been put in by the designer and the programmer of its software. I spent a good while setting the watch up and trying to understand how it worked. In the process I searched on the web and when I found nothing I decided to write up what I had found out. I hope it helps you.

This is just an amateur effort at documentation. It may contain errors or omissions. For confirmation on any matter refer to the actual products sales literature or to the distributor. This is not an endorsement of the watch and in fact my watch just made it through the warranty period before refusing to take a reading.

It is a long while since I have bought a watch of any sort and I was surprised at just how many functions can be provided by modern technology. This is of course a fitness watch but I was surprised to find extensive time keeping features such as 12/24 hour mode : Dual time mode (local time + or - whole hours only) : 8 different alarms that can be set for any day of the week with various fixed text prompts : Back lighting :  6 re-programmable countdown timers with optional rollover : Pacer mode 30-180 BPM : Stop watch 1/100 second :Lap timer 100 laps memory 1/100 second : Total time for all laps : Average lap time : These last two functions are limited (on the watch I tested) to 1 second accuracy which is a pity but this is after all a fitness watch not a super stop watch.

Stop watch displays


The watch came with a fold out book of instructions that were fairly easy to follow and a 12 months guarantee card. The button referred to in the instructions as "SET" is marked on the watch as "LAP" which is no great problem as there is a diagram showing just what is meant.  The  TMR instruction panel (18) should say "Hold down the LIGHT button for  2 seconds" instead of the SET button for 5. The next panel (19) refers to "SET" instead of  "LIGHT" these are minor problems. The translator must have been a bit confused  when describing the PCR Pacer Mode. If you replace "seconds for each step" with "steps per minute" and "in 5 second units" with  "in 5 step units" it all becomes clear.

The real Heart of this watch.

heart reat displayThe nifty function of this watch is its ability to read your heart rate. While wearing it it easy to reach across with your hand and put a finger on each of those prominent pads and in about 5 seconds you have a reading.  You can take a reading when the watch is in any mode and for a few seconds, you can see the rate and the percentage of your maximum heart rate (see later). In heart rate mode you can recall each of the last 100 of your readings showing the date, the time , the  percentage  of maximum and reading number. Pressing another button gets you the lowest and highest readings.  My first use of this watch was to run through my usual exercise taking my heart rate every 5 minutes so I could later plot a graph.  I was exercising at a known rate  so in a few months I will be able to repeat the process and watch my progress.

resting heart rate
At Rest Heart Rate Mode. Is the mode after the Heart Rate memory mode. It is unnamed  and shows a bar graph at the top and the latest resting heart rate.  The rate displayed is used in the calorie consumption calculations and it also goes into the bar graph  so it is important that it has the correct information. Do not use this mode to take a general heart rate. I recommend that you should first take a resting heart rate in some other mode and when you are happy that you are at your most rested, repeat the reading in this mode.

The following modes all have to know  that you are exercising and the watch assumes this whenever the stopwatch is running so if you want to keep long term data on Calorie consumption etc. correct you will not be able to time car races with the stopwatch function. Note the Heart zone, Calories used and the Fat burn displays can be viewed while exercising ie. stop watch running or halted, but they are cleared when the stop watch is reset.

in zone mode display
Heart Rate Zone Mode. This process keeps track of  which  zone your heart rate is in during an exercise period. You can manually set two levels. The time spent exercising below, between and above these levels is recorded and shown on the  IN, HI  and LOW zone displays. You can choose to have these two levels automatically determined for you and then you are given a choice of Health (50-65% 0f EMHR), Fat Burn (55-65% of EHMR) or Fitness (65-80% of EHMR). There is an optional warning tone. Because your heart rate is not being continuously monitored you should take a reading at the start, as soon as your heart is up to speed, then regularly and whenever your exertion level changes.

Calorie Consumption Mode. The heart rate while you exercise is a good indicator of the level of  energy expenditure so with a bit more information the Calories consumed by exercise and thus your weight lose can be estimated. To obtain this there is a Calorie setting mode that allows input of your sex, age (4-99), height
(20-240 cm), weight (20-227 Kg), target calories, maximum heart rate,  and log interval.  With this information  your Body Mass Index (BMI) can be calculated and a determination of your weight class made.  Your class (obese, normal etc.) is indicated with  from 0 to 5 hearts  together  with the BMI.  Note changing the log interval seems to have no effect. It may be used in another model that has continuous heart monitoring.

The Calories used during exercise are calculated  using the elapsed time, the resting heart rate (see above), the latest heart rate and the other information you entered above. See here for my explanation of the formula. Note if you were to exercise and not take any heart rates then the last taken rate would be used and this is meaningless so take readings as soon as your heart speeds up and at any change of pace.

cal display
Provided you have not reset the stop watch you can see the Calories used and a bar graph of arrow heads indicating the progress towards your Target Calories. The display shows the result of 1/2 hour of moderate stationary bike exercise.

Fat burn
There is also a display of the fat loss in pounds for this session.

weekly accum

There is a Weekly Accumulation display that runs Sunday through Saturday and shows the running total.

week 1A current week numeric and chart display that shows the total for the week from Sunday up to the previous midnight. You can show up to 8 previous weeks at a push of the ST/STP button.

Some of the displayed characters are small but this is a great device considering the low price I paid of A$39.99.  I exercised for 1/2 an hour on an ergonometer taking readings every 5 minutes and the Calorie consumption was as expected. I entered in a different body weight and a different resting heart rate and repeated the process and the Calories changed as expected so it takes this information into account. There is a couple of things I would like added. Fat loss in Kg not just pounds, 1/100 sec. reporting of total and average lap time and a mode switch to use the stop watch without it counting calories. I wore the watch all day yesterday and measured my heart rate on a fast walk to the shops. With just a bit more effort I found that I could get my body into the fat burn mode and do myself some good.
Update. I have used this watch every day for about 6 months and it is now a vital part of my exercise programme.
Further update—the watch died just out of warranty but it lead a hard life on a dripping wet wrist and was a low cost product.

If you have any comments or suggestions please contact me (see other pages for mail info.)