An active Marine who trained a lot once told me, "Whenever I do my personal best at bench press my running is way off, and whenever I am at my best at running my bench press suffers". Alan Page was a 260 pound defensive tackle for the Minnesota Vikings. Toward end of his career he had trained for and completed a marathon – the first active NFL player to do so. He lost a significant amount of muscle; so much so that he switched position to linebacker at 225 pounds. When you run great distances carting around more muscle is demanding. You can improve strength and endurance at the same time. Strength and endurance complement each other up to a point. At some point one is going to suffer at the expense of the other. It is best to seek a balance. High Intensity Interval Training (HIIT) for strength will increase both endurance and strength. At Austin Personal Trainingand New Orleans Fitness trainers the trainers can put you through a series of exercises with little rest that will have your heart racing and have your muscles exhausted. Rest, recover, improve, and come back next week stronger with more endurance.