This isn't a full essay but there is some helpful information about Backstrokes. (Tip: Make sure to paraphrase the info you use)
The Backstroke, also known as a back crawl is one out of four swimming styles you can use. Out of the four swimming styles, the backstroke is the easier as far as breathing but maybe be harder to swim hence the fact you can't see. Backstrokes are great for strengthening your upper body and helps tighten your core according to PopSugar. In order to master this style of swimming, you have to have balance. The backstroke engages all of your core.
It's more accurate, especially since heart rate is almost universally measures in beats-per-minute, than, say, timing your pulse for a [factor of 60] seconds (30 seconds, 20 seconds, 15 seconds, 12 seconds, etc.).
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When toxic chemicals used for pest control or for cleaning and sanitizing food contact surfaces and food preparation equipment come into contact with food, the food may be contaminated by those chemicals. Toxic metals such as copper, brass, cadmium, lead and zinc can be a source of chemical contamination.
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