You probably have a general idea, during your workout, of your desired exercise parameters, but there's no substitute for accuracy, especially if your workout is prolonged or intense. Enter the heart rate monitor -- the easiest method to ensure you safely stay in your target training zone. We like this Timex Heart Rate Monitor
($50). Lightweight, a breeze to operate, the heart rate sensor strap (worn on your chest) connects to the monitor and accurately reflects your cardiac intensity; the monitor features a workout timer, cardiac activity review, and an analog heat rate sensor. The monitor is water-resistant, so you can wear it in the shower, but the chest strap is not intended for prolonged immersion (e.g. a pool session). So don't even think about it.
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