At every gym, there is a dark and mysterious place. There are heavy things that can crash and bang, as well as easily hurt someone. I’ve cast surreptitious glances toward this world, even tried to step inside, but it is beyond my comfort zone. I have no problem throwing on bright yellow clothing and running through the streets, or stripping down to a swimsuit and jumping into the pool, but my goodness, the weights area is a scary place.
I have a good idea I’m not the only runner who freezes at the idea of weight training. However, a study published in a recent issue of Cell Metabolism may prompt those of us who are a bit shy in this arena to overcome this self-consciousness and start pumping some iron, especially if weight loss is the name of the game. Resistance training may not only make you stronger, but it may help keep you trim and healthy too.
Distance running and other endurance activities use type I, or slow-twitch muscle fibers. These muscles can work for a long time and burn a lot of calories, as long as there’s oxygen around to make energy. Type II muscle fibers, on the other hand, contract quicker than slow-twitch fibers and are the ones employed in anaerobic activities such as lifting, jumping and sprinting. Researchers from Boston University School of Medicine wanted to see if increasing type II, or fast-twitch fibers, would have any effect on diet-induced obesity.
In the study, the researchers “super-sized” transgenic mice. They fed them on a high fat, high sugar diet to plump them up with fatty tissue. But because it’s easier to get mice to run on a wheel than it is to lift a barbell, the scientists needed some other way to make the fast-twitch muscle fibers grow. They did this by genetically altering the mice so that they could control a gene called Akt1, which stimulates the growth of type IIb muscle fibers.
The researchers found that the mice who built up fast-twitch muscles lost weight and regained normal metabolic conditions without physical activity or changes in their diet. The mice had improved insulin sensitivity, and lower levels of blood glucose, insulin, and leptin. The scientists also found that this effect was reversible. When the gene was inactivated, the muscle mass decreased, the fat mass increased, and metabolic functions suffered.
In this experiment, the mice lost weight and became healthier without lifting a paw. But, what it suggests is that incorporating resistance training into workout plans may help people lose weight and stay healthy. So, for those who run to shed unwanted pounds, it might be time to overcome any fears of the weight room, once and for all.