The mean score is 60 out of 100 and the standard deviation (in other words, the variation in the scores) is 15 marks (see our statistical guides, Measures of Central Tendency and Standard Deviation, for more information about the mean and standard deviation).
What Are the Six Different Types of Swimming Strokes? Swimming provides all-around, low-impact body conditioning as well as exciting competition. Competitive swim meets allow only four strokes -- butterfly, backstroke, breaststroke and the crawl. Two other strokes -- elementary backstroke and sidestroke -- contribute to swimming longer distances, as different sets of muscles are used. The fastest stroke for most swimmers is the front crawl.
Your pectoral muscles, side muscles and obliques pull your arms through the water and back out. In addition, the body roll -- a fundamental aspect of a correctly executed freestyle stroke -- exercises your abdominal muscles and obliques.ighly recommended by doctors and fitness instructors, swimming provides a low-impact, full-body workout that challenges everyone from novice athletes to professional marathon runners. The freestyle stroke, breaststroke, butterfly and backstroke exercise the same major muscle groups of your body.