Monitoring Heart Rate

Heart rate monitors were  in the  realm of science fiction  not  so very long ago. Researchers started checking heart rates around 1912 by using  water buckets as counterweights in the first  laboratory model. The  first  electronic heart rate monitoring tool,  the  electrocardiograph, was originally the size of a room. You would  certainly not want to carry one of those around (if you could afford  one).

Thankfully, we now have  the  personal heart rate monitor in a variety of models. It may not  do  everything the  electrocardiograph in your  doctor’s office does, but  it very  nicely meets the  needs of people who  want  to accurately measure their heart  rate and  use  that information to create their own individualized fitness programs. Today’s heart rate monitors are the  size of a wristwatch and  the  price of a pair  of good-quality athletic shoes.

As introduced earlier, a heart rate monitor provides biofeedback about the  heart.  It accurately reports the average number of times the heart contracts in one minute by picking up the  electrical signals given  off by the  heart and  then transmitting this  information to the  receiver.

The  terms heart  rate monitor  and  heart  rate watch  are  synonymous. Most,  but  not  all, monitors are watches. The monitor itself (the receiver) collects the output data transmitted from  the  transmitter and  processes it through a computer chip  to calculate a heart rate number. This number is updated every three to five seconds. When you turn on a heart rate monitor, ignore the  first  few readings that appear; the  software inside the  monitor needs several sample heart rate readings before it can  accurately calculate a value.  Likewise,  if you  quickly  increase or decrease exercise intensity during training, the  heart rate values displayed will always lag slightly behind your  real-time heart rate.

There are three components to most analog or digital wrist heart rate monitors: an elastic chest strap, a transmitter, and  a receiver, or wrist  monitor. Some wrist  models have  only two pieces because the chest strap and transmitter are combined. Projection monitors also have  only two parts, the  elastic chest strap and  the  transmitter.

• Chest strap. This adjustable elastic belt is worn  snugly  around the  chest, usually just below  the  nipple line. Attached to the  elastic chest strap is the  transmitter unit.
• Transmitter. The transmitter attaches to or is part of the chest strap. The transmitter picks up the electrical signal, translates it into data, and sends the data to the wrist monitor via an electromagnetic field, similar to a radio wave.
• Wrist monitor. The wrist  monitor (receiver) looks  like a wristwatch and  functions as the  receiver of the  transmitter’s signals. Different  wrist  monitors give different displays, but  the  basic information is the  same: they  display heart rate in beats per  minute (bpm) (see figure 1.1).
• Projection receiver. Sometimes referred to as a team system, this style  of receiver collects individual data streams from multiple transmitter belts consecutively and sends them to a computer that displays all heart rates on a screen on the  wall. The pod  is connected to the  PC via a USB cable.