Our clients at Austin Personal Trainers and New Orleans Personal Trainers cover a wide spectrum of ages not least of which are those who are older. Our oldest client was 95, and one of our trainers has four clients over eighty. People in this cohort of the population have the most to gain in quality and length of life.
Increased strength will result in increased gait speed, and that will result in better balance. Strength training will result in stronger muscles yes, but bones become stronger as well. Elderly that are stronger are less likely to fall, and if they do they are more likely to walk away unscathed.
People are not usually placed in nursing homes because they are out of breath; it is usually because they are too weak to carry out daily activities on their own. Strength is key not cardiovascular ability. The muscles push the heart, not the other way around. If your muscles are so weak that you cannot stress the cardiovascular system the cardiovascular downgrades its ability to handle cardiovascular stress. When a body is able to perform work of a demanding nature (strength training) the cardiovascular system is positively stressed and upgrades its ability to do demanding work. Win, Win, Win - stronger muscles, bones and heart.
For years the conventional wisdom stressed aerobic activity at the expense of anaerobic activities (strength training), but that has shifted in recent years. This Forbes article gives further incite: Why Strength Training May Help You Live Longer. A whole slew of blog entries dealing with aging can be found here.