Background Paragraph: In exercises such as weight lifting, skeletal muscle contracts against a resisting force (see Figure below ). Using skeletal muscle in this way increases its size and strength. In exercises such as running, the cardiac muscle contracts faster and the heart pumps more blood. Using cardiac muscle in this way increases its strength and efficiency. Continued exercise is necessary to maintain bigger, stronger muscles. If you don’t use a muscle, it will get smaller and weaker—so use it or lose it. 
Story: Two groups of athletes started new training routines this year.  Group A started weight lifting for three months, while Group B, did running exercises.
Which group will get increased muscle size and strength? Which group will not get increased muscle size? Which group's cardiac muscle contracts faster? Which group's cardiac muscle contracts slower? Which group's hearts will pump less blood? Which group's hearts will pump more blood? Which group's method of exercise contributed to increased strength and efficiency? Which group's method of exercise did not contribue to increased efficiency? Which group's skeletal muscles contract against a resisting force? Which group's skeletal muscles do not contract against a resisting force?