A co-worker of mine did a presentation this morning on the topic of resistance training versus aerobic training, especially for the female population. If you go into any gym you will see that most of the cardio equipment is occupied by females and very rarely do you see a female lifting weights in the area of free weights. My co-worker talked about the misconceptions that females have about resistance training as well as the benefits of weights versus the negative effects of long distance aerobic training. There is a lot of research being done on this topic as of late and a lot of talk by specialists such as Alwyn Cosgrove.
Resistance training is an overall better approach to body composition goals than is long distance aerobic training. Resistance training will strengthen the muscles which in turn makes them "tight" looking and gives the body definition. Along with this there is the effect of "afterburn" in which the body burns more calories, and more calories from fat many hours after the training session is over. With long distance aerobic training there are more calories burned during the actual training session than with resistance training or interval training, but the "afterburn" effect with resistance and interval training compensates for this and creates a larger calorie usage.
Resistance training is used by a lot of people in an incorrect manor as well. There are many people, especially females, who want to "tone" and resistance train using dumbells that are maybe 5% of the actual weight they can lift. When resistance training, one should use a weight that they can only complete about 10-15 reps. The reps that are completed should be a challenge and weights should be increased when the current weight is no longer difficult. Results come from effort and if a large effort is not needed then the results are not going to be maximal.
Solely doing cardio training can lead to complications later in life. For instance, strength will not be there to complete daily activities when one becomes elderly. Also for women, there will be a greater chance for osteopenia. With resistance training bone density is increased but with endurance training and long distance running bone resorption is increased. Women are already more likely to have bone deficiencies when they get older so resistance training is needed to combat this. Stress fractures, joint and back problems are also results from large amounts of running.
I will add this...I am not saying that no one should run long distances. If you are an athlete competing in a sport such as cross country or marathons, then you obviously need to train by running long distances. However, incorporating resistance training into a regemine will increase your quality of life as well as performance. So there are some people out there who need to train aerobically, but for the average person just looking to cut fat and look good naked, resistance training and interval training are a much better and more efficient option.
This is just a brief overview of the topic. For more information check out the work by Alwyn Cosgrove. Also check out the book, "The New Rules of Lifting for Women" by Lou Schuler and Cassandra Forsythe.