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 soldiers started different training programs. Blue group did weight training for 3 months, while Brown group ran 3 miles a day for three months. The Captain observed different results on each group.
Which group didn't have their cardiac muscles contract as fast while training? Which group didn't have their hearts pumping more blood while training? Which group didn't increase the efficiency of their cardiac muscle as much as the other group? Which group didn't increase the size of their muscles? Which group didn't increase the strength of their cardiac muscle as much as the other group? Which group had their cardiac muscles contract faster while training? Which group had their hearts pumping more blood while training? Which group increased the efficiency of their cardiac muscle? Which group increased the strength of their cardiac muscle? Which group increased the strength of their muscles?