If you want to open a .oar file on your computer, you just need to have the appropriate program installed. To open this file, Windows needs to know what program you want to use to open it. Windows can go online to look it up automatically, or you can manually select from a list of programs that are installed on your computer.
Biological Oxygen Demand (BOD) is a measure of the oxygen used by microorganisms to decompose this waste. If there is a large quantity of organic waste in the water supply, there will also be a lot of bacteria present working to decompose this waste. In this case, the demand for oxygen will be high (due to all the bacteria) so the BOD level will be high. As the waste is consumed or dispersed through the water, BOD levels will begin to decline. Nitrates and phosphates in a body of water can contribute to high BOD levels.
The VO2max or maximal oxygen uptake is a key physiological measure of cardiovascular fitness and can help to explain differences in sporting performance between individuals. It tells us the maximum amount of oxygen that our bodies are able to consume when exercising.