The first came from Dr. Dean Ornish and was posted on his facebook page. It was a Huffington Post article with the puzzling title: "Weight loss exercise: What's cardio or strength training?" I assume the word "better" is missing from that title.
Researchers gave three different exercise protocols to participants: either aerobic activity only, equivalent to about 12 miles or 133 minutes per week; resistance training only, meaning three days per week of lifting weights for a total 180 minutes per week; or a combination of aerobic activity and weight lifting for a total 313 minutes per week. Before and after the exercise regimen, they tested the body compositions of each person.Because the study found that the cardio-only group lost the most weight and fat, we are supposed to conclude that cardio-only is the best way to exercise, and though the cardio-and-weights group lost the most in waist circumference and the weights-only group gained the most in lean-body mass, that did not translate to weight loss. The weights-only group also gained a little bit of weight overall. The HuffPo conclusion is that "aerobic exercise beat out resistance training and a combination of aerobic and resistance training in terms of losing fat mass."
What the HuffPo article does not tell us is how long the study lasted or how much difference was found between the groups. Just because a difference is significant in statistical terms (that is, not due to chance) does not mean it is important. I found the original article and it seems that the HuffPo article misrepresents the results somewhat. The resistance-only group gained a little more than a half pound of weight overall, but gained more than a pound of lean-body mass. The aerobic-only group lost almost 2 pounds on average, but also lost some lean-body mass. The aerobic-and-resistance group lost almost as much weight as the aerobic-only group and also put on almost as much lean mass as the resistance-only group, while also seeing a change of almost two inches in their waist circumference, more than the other two groups combined. Since the study only lasted four months, the conclusion I would come to is that combining both exercises would promise the best results in the long run.
The second article was linked from Dr. Yoni Freedhoff's great blog Weighty Matters. He calls it a "fun piece," and as it appears in Men's Journal, I guess I shouldn't have been surprised that it is written in that macho, combative style so common to sportswriting and articles like this one. It's called "Everything You Know About Fitness is a Lie," and calls gyms the "enemy" because they tend to have more cardio and Nautilus machines than free weights. This is more of an anectdotal piece than one that claims to be research-based, and it comes down in favor of high-powered, explosive strength training to the exclusion of almost everything else except a few games of Ultimate Frisbee or other actual sports. I have to say I agree that the elliptical machines and treadmills are a "pale substitute" for real outdoor activity. I'm just not sure that the kind of training this unnamed (at least online) author suggests would be practical or even safe for the average person who doesn't have access to a strength-training expert as a guide.
I'm not sure that most people even need to know what kind of exercise is "best." As Author Gretchen Reynolds pointed out in The First 20 Minutes: Surprising Science Reveals How We Can: Exercise Better, Train Smarter, Live Longer, most Americans do so little exercise that the first twenty minutes off the couch is the biggest victory, and everything after that is gravy.
I would ask a different question. What are you training for? I know that most people think of exercise only as a means to weight loss, but think a little more like an athlete for a minute. If you want to be able to run a marathon, the most important exercise to do is running, with maybe some strength work and cross-training for injury prevention. If you want to be able to bench-press hundreds of pounds, you should probably focus on strength.
I remember helping a friend and her (thankfully ex-) husband move. He was a body builder and had huge muscles and hundreds of pounds of weights. He did not, however, participate in the move because he didn't want to hurt his back. Either his big muscles were totally useless, or he was a lazy jerk (probably both). I fumed for the whole day at what a waste it was to have a guy like this who spent so much time lifting weights but couldn't actually carry them around outside the weight room.
The point is that fitness is about being "fit" to do the things that we want to do, and not just a euphemism for losing weight and having six-pack abs. For most of us, who want to face the challenges of an active, busy life, a combination of strength, flexibility, and endurance work is important. And just like most foods are actually a mix of carbs, proteins, and fats, many exercises also have components of each. I personally believe that varying activities is the safest and best training, but I'm not a researcher or a Men's Journal writer, so what do I know?