We all know exercise is your best shot at having a healthy heart, a strong immune system, and maybe even a 100th birthday party. Years of research have also shown that an active lifestyle boosts memory and cognitive capacity, and can slow the progress of neurodegenerative disease. But what actually changes in the brain when we go for a run? New research is showing some of the molecular reasons why keeping fit also keeps you sharp, and it has to do with your brain’s untapped potential for growth.
Dr. Fred Gage of the Salk Institute has been hunting down the neuronal consequences of exercise for over a decade. In 1998, Gage and colleague Peter Eriksson rocked the neuroscience world with their discovery that humans keep producing new neurons throughout adulthood. He also showed that mice and rats that regularly ran on exercise wheels grew more neurons than a couch-potato control group. But until recently, the mechanisms of this process have been poorly understood.
Recently, Gage and collaborators have been publishing a variety of papers describing the molecular pathways by which exercise leads to brain growth. Gage’s work in the 90’s showed that our brains have a store of stem cells that lie largely dormant, waiting for some stimulus to initiate cell division. A growth factor called bone morphogenetic protein (BMP) works to control cell division throughout the body, including in the brain. The more BMP, the less growth. Regulatory factors like BMP are essential to a healthy body; studies have shown that the absence of BMP activity is linked to colon cancer.
But as we get older, higher counts of BMP accumulate in the brain and keep our neural stem cells asleep. This is where exercise comes in. Within one week of being given an exercise wheel, mice showed half as much BMP signaling in their brains. The mice also showed increased levels of the protein Noggin (yes, I know), which acts as a BMP-antagonist. There are still questions as to whether exercise directly decreases BMP, or does so indirectly via Noggin production. Either way, stem cells begin to divide and new neurons are born.
Gage has observed that neurogenesis is pronounced in the hippocampus, a brain structure that is essential to long-term memory and navigating space. This could help to explain how exercise helps mitigate the effects of Alzheimer’s disease; as AD progresses, the hippocampus is the first target of severe neurodegeneration. When researchers pumped mice full of Noggin, they saw huge improvements in their maze running skills (mostly memory and spatial navigation, i.e hippocampal functions).
Dr. Fred Gage in his element
Researchers have long known about the link between exercise and brain function. In elderly populations, even small amounts of daily exercise showed increased levels of concentration, learning ability, and abstract reasoning – not to mention memory. Most theories have cited increased blood flow & better oxygen delivery to the brain as the major mental health benefits of exercise, and this is undoubtedly true. But these new relationships help to tease out some of the other molecular mechanisms at work when we’re at play.
But don’t start lining up for Noggin injections just yet. Like most biological systems of balance, the relationship between BMP and Noggin is an important one. A recent study showed that neurons placed in Noggin-soaked petri dishes stopped BMP signaling altogether, with some undesirable effects. As predicted, the stem cells divided out of control and were eventually used up; after a few weeks, neurogenesis slowed to a creep. BMP is an essential ingredient to keeping the brain’s stem cell stores intact.
So the next time you sit down to watch television, or, um, surf the internet, remember: your BMP count might be getting into dangerous territory. Best case scenario, you’ll be forgetting things faster in your twilight years. Worst case scenario? Death.
When you go to the gym, do you wash your hands before and after using the equipment? Bring your own regularly cleaned mat for floor exercises? Shower with antibacterial soap and put on clean clothes immediately after your workout? Use only your own towels, razors, bar soap, water bottles?
If you answered “no” to any of the above, you could wind up with one of the many skin infections that can spread like wildfire in athletic settings. In June, the National Athletic Trainers’ Association, known as N.A.T.A., issued a position paper on the causes, prevention and treatment of skin diseases in athletes that could just as well apply to anyone who works out in a communal setting, be it a school, commercial gym or Y.
The authors pointed out that “skin infections in athletes are extremely common” and account for more than half the outbreaks of infectious diseases that occur among participants in competitive sports. And if you think skin problems are minor, consider what happened to Kyle Frey, a 21-year-old junior and competitive wrestler at Drexel University in Philadelphia.
Mr. Frey noticed a pimple on his arm last winter but thought little of it. He competed in a match on a Saturday, but by the next morning the pimple had grown to the size of his biceps and had become very painful.
His athletic trainer sent him straight to the emergency room, where the lesion was lanced and cultured. Two days later, he learned he had MRSA, the potentially deadly staphylococcus infection that is resistant to most antibiotics.
Mr. Frey spent five days in the hospital, where the lesion was surgically cleaned and stitched and treated with antibiotics that cleared the infection. He said in an interview that he does not know how he acquired MRSA: “The wrestling mat might have been contaminated, or I wrestled with someone who had the infection.”
If it could happen to Mr. Frey, who said he has always been health-conscious in the gym and careful about not sharing his belongings, it could happen to you.
The Risks
Recreational athletes as well as participants in organized sports are prone to fungal, viral and bacterial skin infections. Sweat, abrasion and direct or indirect contact with the lesions and secretions of others combine to make every athlete’s skin vulnerable to a host of problems. While MRSA may be the most serious skin infection, athlete’s foot, jock itch, boils, impetigo, herpes simplex and ringworm, among others, are not exactly fun or attractive.
Athletes who are infected should be kept from competing in matches for a week or more until treatment renders them noninfectious. The authors of the trainers’ study warned against simply covering infections like herpes and active bacterial lesions in order to return to competition.
Likewise, people like you and me who work out at a facility or swim in a public pool should stay away until cleared by a doctor who is well versed in skin diseases.
Steven M. Zinder, a trainer at the University of North Carolina at Chapel Hill and chief author of the new paper, said in an interview that these recommendations are not esoteric.
“It’s what we all learned — or should have learned — in sixth-grade health class,” he said. “It’s all common sense. You need to keep yourself and your equipment clean. You never know who last used the equipment in a gym. It can be a great breeding ground for these bugs, some of which are pretty nasty.”
The report, published in the August issue of The Journal of Athletic Training, stated, “Athletes must shower after every practice and game with an antibacterial soap and water over the entire body.”
Dr. Zinder noted that after a workout, women tend not to shower at the facility, while men, who are more likely to shower, often fail to cleanse their entire bodies, including their feet. Well-equipped facilities should provide antibacterial liquid soap.
“You should be showering at the gym and putting on clean clothes that are kept separate from the dirty ones,” he said. In fact, he added, it’s best to have two bags, one only for clean clothes, and to wash the dirty-clothes bag now and then.
Assume Exposure
Jack Foley, athletic trainer and director of sports medicine at Lehigh University in Bethlehem, Pa., and co-author of the report, said athletes should always assume they are exposed to skin infections.
At any given time, he said in an interview, one person in three in the United States suffers from a skin disease that can be spread to others, even while in the incubation stage.
The report noted that there had been “an alarming increase in the prevalence of MRSA” in the noses of both healthy children and adults. Thus, sneezing into one’s hand or blowing one’s nose without washing with an antibacterial cleanser afterward may spread these dangerous bacteria to others.
While hand hygiene is most important over all , avoiding fungal infections requires a daily change of athletic socks and underwear; carefully drying the armpits and groin and between toes (perhaps blow-drying the feet on low heat); and using foot powder. Shower shoes can help prevent infection as long as they don’t keep you from soaping your feet.
A viral infection called molluscum contagiosum may not be on the popular tongue, but it is commonly seen in young children and , spread through skin-to-skin contact, is not uncommon among athletes, including swimmers, cross-country runners and wrestlers, the report stated.
Prevention of this highly contagious infection requires “meticulous hygiene” after contact with secretions from other athletes through benches, towels and mats.
If you plan to work out in a gym or use a locker room, Mr. Foley suggested that before choosing a facility, you quiz the management about the cleaning agents used (they should be approved by the Environmental Protection Agency) and daily cleaning schedule for all surfaces and equipment. If exercise mats are not cleaned between classes, he suggested bringing your own. Antibacterial wipes or spray bottles should be provided and used by everyone to clean equipment after a workout.
