To get the most of out of using a heart rate monitor chest strap device, it is important to understand the basics of how these devices work and what you can do to ensure they work as expected.  This article references the M7, but the general content is true for all brands of heart rate monitors.

Here are some tips for using a heart rate monitor chest strap:


Fit:

The strap should be snug but comfortable, and shouldn't restrict breathing or movement.  The M7 strap needs good skin contact.  If the strap is too loose, it may move around when you’re training and lose skin contact.  
We have two different strap sizes available.  Strap size is chosen at the time of checkout during the purchase process but if you need an extra strap or a different size, you can get one at the appropriate link below.

Wearable size (XS-S):  20″ to 28″ (51 to 71 cm) with max stretch at largest setting to fit 30″ (76cm)

https://eza.infusionsoft.com/app/orderForms/m7-replacement-strap-small 

Wearable size (M-XXL):  26” to 36” (66 to 92 cm) with max stretch at largest setting to fit 60″ (153cm)
https://eza.infusionsoft.com/app/orderForms/M7-strap-regular 


Placement:

The M7 should be placed directly underneath the pectoral muscles with the sensor over the bottom of the sternum.  Below represents how the M7 should be positioned for men (left) and women (right).  Note that it is also acceptable for women to slide the M7 strap and transmitter under the bottom of a bra. 

Note:  Some people may benefit from shifting the transmitter slightly to the left instead of having it centered.  This may place the electrode area of the strap closer to the heart.

Important: You will need to turn the M7 on before you can connect it to the Morpheus app. To do this, put the chest strap on as indicated below.

Best steps for putting on the M7:

  1. To get the most immediate and stable connection when attaching the M7 transmitter to the strap, as well as the most accurate heart rate reading during workouts, the M7 strap needs to have good skin contact and needs to have a good amount of moisture on it to support the electrical HR signal (see below).  
    • Put the chest strap on your body correctly and tight enough so it doesn't slide down.  It is adjustable to get it just right for you.  Do this without the transmitter snapped onto it.
  2. Just before you are about to use the HRM (ie start a recovery test or start a workout), put a fair amount water and/or electrode gel on the skin side of the strap on the rubber sections to the left and right of the middle.  Just use a water source of some kind such as a sink (not filtered water because that has all the conductive components removed) and get your fingers wet and rub them under the strap left and right of the center.  
    • Do this a few times so that water gets on your skin and the electrode pads of the strap.  If you do this after you are already wearing the strap then it will be less likely to rub off of your skin or the strap and will trap the moisture there which will create a great electrical signal from the moment that you snap the transmitter onto the strap.  The more dry your training atmosphere is and the more dry your skin is, the more important this step of the process becomes.  
    • Also, it's not a bad idea to put a bit of water on the front side of the strap to prevent static electricity interference from your clothing.
  3. Finally, fully attach the transmitter to the strap by snapping it onto both ports.  Ensure that it is attached right side up and not upside down.  
    • You will hear a single audible beep and the LED light will turn on and blink when it's been activated.  It will blink a few times in a white color while searching for HR and then it will blink blue for 10 seconds after it has found solid HR signal.  After that the LED will shut off, but the device remains powered on and active.
If the electrical signal is good enough because of the moisture and the strap is in good condition and isn’t too old so that the electrodes are wearing out (a new strap will eventually be needed but that is usually roughly a once per year thing), then there’s no reason why it won’t work well if following the process above.  


Sensor Orientation: 

In order to read accurately, the heart rate sensor must be snapped into the chest strap so that the Morpheus logo is right side up and could be read by someone facing you.  This means when you snap the sensor into the chest strap, the Left snap should be on the left side of your body and the Right snap should be on the right.  The back side of the sensor also has L and R next to the pins.  The circular LED light on the front of the device will be on the left side of your body.

General Maintenance:

Heart rate monitor straps need to be free of non-conductive residues to sense the electrical activity of our heart and send that info from the strap to the transmitter.  If the electrode area of the strap and the connection ports that the transmitter snaps onto get too dirty, then they need to be cleaned.  After each use, rinse the belt with water, gently wipe it off, and let it dry to prevent sweat residue buildup.  Once every couple of weeks, do a deeper clean of the strap.

See the full details in the question about cleaning at the FAQ link below.

https://trainwithmorpheus.com/topic/m7-heart-rate-monitor/

When you are not wearing the M7, always completely unsnap the transmitter from the chest strap to prevent it from power cycling on and off continuously.  Wipe off the pins on the back of the transmitter with a towel and wipe of and/or rinse the strap under warm water and wipe it dry.  Store the transmitter in a way that it is not in contact with anything conductive so that it remains powered off.

Normal wear and tear:

The M7 strap is made from nylon, spandex, and rubber, which eventually wear out over time.

Routine wear-and-tear isn’t always visible, since the electrodes are covered by rubber strips and may lose effectiveness below the surface.

If the electrodes are not working properly, they cannot accurately measure your heart’s electrical signal.

If you are following the steps above to get accurate and consistent readings, and then the readings become inaccurate and/or you start to experience disconnections, it may be time for a new strap.