Here are the answers you chose (in pink), and my comments about your answers (in blue). If you didn't answer all of the questions correctly, you might want to click Previous to try them again. 1. Which fiber types are recruited for light-intensity activities?       You chose the following answer(s):       No, that's incorrect. Spend more time looking at the graph. Keep in mind that only up to about 30% of the muscle fibers will be called into play for a light activity. Try this one again. 2. Which fiber types are recruited during a maximum-effort activity?       You chose the following answer(s):       No, you've missed something. Notice that as the intensity increases, the percent of fibers used increases. A muscle fiber has what's called a recruitment threshold. The smaller fibers (ST) are easiest to recruit, and therefore are first to be recruited. The demand has to be higher for the FTa and even higher for the FTb fiber types. As the intensity of the exercise increases, more fibers are added (motor unit summation). The ST fibers don't shut off -- the FT are just added on. Take another look at the illustration and try this one again. 3. Which fiber types are most likely to be recruited for anaerobic activities?       You chose the following answer(s):       Think again. During anaerobic activities, the intensity is near maximum. Which fiber types are recruited during this type of activity? Look at the graph and try this one again.