Task: Question Generation
Input (English): 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.
Output (English): Which group didn't increase the efficiency of their cardiac muscle as much as the other group?