Once you know your threshold, you can monitor yourself to discover when you are beyond your AT. One way to track your heart rate is to count the beats, as I did, but other people use a heart rate monitor, an inexpensive machine available for $30 and up.
Monitoring heart rate has at least five benefits.
First, it offers control. In the words of one person bedbound with CFS, "I craved a boundary, something I could see or touch that would tell me what was too much. My heart rate monitor is drawing my boundaries for me. When I can manage to get up and move around, but keep my heart rate below 105 beats per minute [her AT], then I know I am safe to continue to do so."
Second, wearing a monitor often leads to recognition of previously unknown limits. In the words of one person, "Just getting the heart rate monitor was a huge eye opener for me...Everything put me over the threshold" Another said, "It was quite shocking to find that I operated routinely above my AT."
Third, the alarm feature of a heart rate monitor tells you when you're about to go outside your limits and alerts you to the need to take a break. As one person says, "We set my monitor to alarm when I reached a bit below my anaerobic threshold. That audible heart rate alarm was the best training tool I could have had."
Fourth, awareness of limits can suggest how to change. One person found that just going up a flight of stairs pushed her heart rate beyond her threshold. Her solution was to stop halfway and rest. Another person says that lifting her daughter used to push her over the edge. Her solution was to sit down and have the child climb into her lap. A third person found that many activities put her over her limit. She has found ways to be active with less exertion. For example, she now uses a rolling chair in the kitchen, empties the dishwasher in stages, and uses a grabber to pick up things without having to bend over.
Fifth, the monitor helps educate others about limits and to elicit their help. As one person said, "Using the monitor helped my family to understand and they helped me to stop when it went off."