Stronger Muscles - Better Brain
Several other studies have looked at the impact of resistance training on people with mild cognitive impairment (MCI). They also found significant improvements in cognitive function. MCI is the “senior moments” kind of memory impairment that sometimes (but not always) may signal the onset of Alzheimer’s disease. The most important of the MCI investigations was led by Dr. YorgiMavros from the University of Sydney. It included a hundred men and women, aged 55-68, divided into four groups. The first was assigned to do resistance training, including weightlifting. They pushed themselves to exert 80% of their peak strength. The weights were gradually increased as participants got stronger. As you would expect with muscle-building, they could gradually handle more and more weight, and throughout the program they aimed to use 80% of their strength on each repetition. A second group performed a “placebo exercise.” They were told to stretch while in a sitting position (my kind of exercise, ha!) The third group carried out a computerized cognitive training program, and the fourth was given its placebo equivalent. Each participant performed his or her assigned activities two to three times a week for six months.Real Exercise for Real Brainpower
The key finding was that only the first group demonstrated gains in cognition. You have to do real exercise, the kind that adds to muscle strength. The greater the muscle strength gains, the greater the brain benefits. "The more we can get people doing resistance training like weightlifting, the more likely we are to have a healthier aging population," said Dr. Mavros. "The key, however, is to make sure you are doing it frequently, at least twice a week, and at a high intensity so that you are maximizing your strength gains. This will give you the maximum benefit for your brain." Although muscle strength is clearly connected to cognition, the mechanism behind it is unclear, so researchers from the University of Missouri in Columbia carried out an experiment to find out.Weight Training for Rats
In humans, a small number of studies have suggested resistance training reduces serum homocysteine, a brain-and-heart-harming toxic byproduct of protein metabolism. One way homocysteine hurts your brain is by reducing insulin-like growth factor 1 (IGF-1). Now, IGF-1 and insulin are not the same; insulin regulates sugar levels in the cells and blood whereas IGF-1 stimulates the growth of cells, such as brain cells. But to look more closely at what molecular changes resistance training produces in the brain, the Missouri scientists needed a different type of experiment. So they devised a method of inducing rats to carry out resistance training by attaching weights to the rodents' rear ends and placing a food reward at the top of a three-foot ladder. The animals were divided into three groups. One acted as a control while the other two were injected with a toxin that induces a rodent form of MCI. Of the group that had MCI, half began weight training, with the weights increasing as it became easier to climb the ladder, while the other half did no weight training. After five weeks the scientists tested their cognition using a maze. In the early tests the control rodents completed the tests faster and with greater accuracy. But in later tests, remarkably, the MCI weight lifters caught up to the control animals and in some cases even surpassed them for speed and accuracy. Meanwhile, the untrained MCI group lagged far behind.Restores Ability to Think
Lead author Dr. Taylor Kelty said that resistance training had "effectively restored" their ability to think. Examining brain tissue of the rats that exercised, the researchers found that the toxin had induced inflammation, as expected. They also discovered enzymes and genetic markers known to stimulate the creation and survival of new neurons while also boosting plasticity -- the brain's ability to modify its connections or re-wire itself. Their research also confirmed human studies showing resistance training not only protects levels of IGF-1; it activates IGF-1 signaling in the hippocampus, a key learning and memory center of the brain. Dr. Kelty commented, “I think it’s safe to say that people should look into doing some resistance training. It’s good for you for all kinds of other reasons, and it appears to be neuroprotective. And who doesn’t want a healthy brain?”