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.
LOSEIT (iPod Touch, iPad andiPhone; free)
Tell the app how much weight you want to lose and how many pounds per week you want to take off, and it calculates the amount of calories you can consume each day. LoseIt has a database of 40,000 food items and can also calculate how many calories your daily exercise burns up.
CALORIE COUNTER by FatSecret (works on all platforms; free)
This program works much like LoseIt. But one advantage is that when you enter your basic information, you can sync up with the FatSecret Web site. The site has forums where users can swap ideas about diets, recipes and working out.
TAP & TRACK (iPhone, iPod Touch and iPad; $3.99)
This app costs $4, but users say it’s worth every penny. The program helps you come up with a daily calorie goal and features a large food and exercise database.
WEIGHT WATCHERS MOBILE (iPhone, iPod Touch and iPad, BlackBerry and Windows Mobile 6; subscription required)
If you already follow Weight Watchers or Weight Watchers Online, consider their app or one that can track the points used in their diets. Free for online subscribers, Weight Watchers Mobile lets you track and calculate points and see your weight loss history.
If you are what you eat, then I should weigh-in at under $1 a pound.
That's because, as a general rule of thumb, I try to only buy foodstuff that costs under a buck per pound. Under $1 a pound, year-round — that's my grocery shopping mantra.
It's not just because I'm a world-class penny-pincher and smart shopper; believe it or not, it's also about eating healthier. When you look at the USDA "food pyramid," many of the things we should be eating the most of — grains, legumes, fruits and vegetables — happen to cost the least. It's often the stuff that's bad for us (at least in large quantities) — red meat, fatty dairy products, and processed foods high in trans saturated fats — that cost the most, on a per pound basis.
To prove my point, I've put together this list of 50 healthy foods that I've purchased at least once in the last six months for under $1 a pound. First, a few disclaimers about my list-o-fifty:
So rev-up your shopping cart, but be careful: There's a Green Cheapskate loose on aisle five!
Apples - One a day keeps the cheapskate away.
Asparagus - HUGE store special at 99 cents a pound during Easter week. I bought 10 pounds, blanched it and then froze it.
Bananas - Potassium for pennies.
Barley - A tasty alternative to rice and potatoes.
Beans - (canned or dried) Kidney, pinto, navy, black, red, and many more.
Bok Choy - Steam and serve with a little soy sauce.
Broccoli - Yes, a store special. Usually closer to $2 per pound.
Bulgar Wheat - Try it in pilaf or a tabouleh salad.
Cabbage - Green and red -- I like mine fried.
Cantaloupe - No, sorry, I can't; I'm already married.
Carrots - Raw or steamed; rich in carotenes, a healthy antioxidant.
Celery - Stir fry it for a change.
Chicken - Whole or various parts, on sale.
Chickpeas - AKA garbanzo beans -- mash 'em up as a healthy sandwich spread.
Cornmeal - "Polenta" is all the rage these days, but I loved it 40 years ago when Mom called it "cornmeal mush."
Cucumbers - Try peeling, seeding, and steaming with a little butter and salt.
Daikon Radish - My new favorite raw veggie.
Eggs - Don't overdo them, but eggs provide high quality protein and still cost about $1 per pound. (Plus, there are many eggscellent things you can do with the shells.)
Green Beans - Frozen, but fresh are sometimes on sale for under $1 a pound in-season.
Greens - Kale, mustard, turnip, and collard greens are rich in vitamins and a good source of fiber. Here's how I cook 'em.
Grapes - Store special @ .99 a pound.
Grapefruit - Bake with a little brown sugar on top for a healthy dessert.
Lentils - Perhaps the perfect food -- healthy, cheap, and versatile (think soups, salads, sandwich spreads -- and those are only some of the "s" possibilities).
Liver - Chicken livers usually cost under $1 a pound, and sometimes beef and pork liver can be found in the DMZ ("Dollar Maximum Zone").
Mangoes - High in fiber and vitamins A, B6, and C.
Milk - Yep, on a per-pound basis, milk still costs well under $1 a pound.
Napa Cabbage - Delicious steamed or raw in a salad.
Oatmeal - The good old-fashioned "slow cooking" kind...that takes all of five minutes.
Onions - Try baking them whole in a cream sauce.
Oranges - Frequent sale price when in-season.
Pasta - Store special @ .89 a pound -- I nearly bought them out!
Peanut Butter - Special sale price, but stock up because it usually has a long shelf life.
Pork - Inexpensive cuts of pork frequently go on sale for 99 cents per pound or less; sometimes even ham during the holidays.
Potatoes - White and red - baked, mashed, boiled, broiled, steamed.
Pumpkin - Yes, you can eat the same ones you buy as holiday decorations, and they usually cost under 50 cents a pound.
Rice - White for under $1 a pound; brown, a little more expensive but better for you.
Rutabagas - Hated them as a kid; can't get enough of them now.
Sour Cream - 99 cents on sale, but long shelf life, so stock up. My cucumber awaits.
Spinach - Frozen (but Popeye doesn't care).
Split peas - Add a hambone and make the ultimate comfort soup. Try it in the crock-pot!
Squash - Try baking acorn squash with a little brown sugar.
Sweet corn - Canned, or fresh on the cob, in-season. (Try this recipe for summer corn fritters.)
Tomatoes (canned) - Canned are often better than fresh to use in cooking, and occasionally you can find fresh on sale for under a buck, in-season.
Turkey - A popular bargain priced loss-leader around the holidays -- buy an extra bird and freeze it for later.
Turnips - Make me think of my grandparents, who always grew them.
Watermelon - Whole, in-season melons can sometime cost less than 20 cents a pound if they're on sale and you find a big one.
Wine - Well, at least the stuff I drink - 5 liter box (approximately 11 pounds) for about ten bucks, on sale. (BTW, the beer I drink is even less expensive per pound.)
Yams/Sweet Potatoes - One of the healthiest foods you can eat, and usually available year around for under $1 a pound.
Yogurt - 8-ounce containers on sale two for $1.
Zucchini - OK, they're a type of squash (above). But I love them so much they deserve their own place on the list. Plus they look great in pantyhose.
Now look at all the money you've saved!
Photo by rbrwr.
We've covered all kinds of caffeine "hacks" here at Lifehacker, from taking "caffeine naps" togetting "optimally wired." And, of course, we're obsessed with the perfect cup of coffee. But when it comes to why so many of us love our coffee, tea, soda, or energy drink fixes, and what they actually do to our busy brains, we've never really dug in.
What follows is a brief explainer on how caffeine affects productivity, drawn from Buzz and other sources noted at bottom. We also sent Braun a few of the questions that arose while reading, and he graciously agreed to answer them.
Right off the bat, it's worth stating again: the human brain, and caffeine, are nowhere near totally understood and easily explained by modern science. That said, there is a consensus on how a compound found all over nature, caffeine, affects the mind.
Update: Commenter dangermou5e reminds us of web comic The Oatmeal's take on adenosine and caffeine. It's concise:
It's an apt metaphor, because it spells out that caffeine very clearly doesn't press the "gas" on your brain, and that it only blocks a "primary" brake. There are other compounds and receptors that have an effect on what your energy levels feel like—GABA, for example—but caffeine is crude way of preventing your brain from bringing things to a halt. "You can," Braun writes, "get wired only to the extent that your natural excitatory neurotransmitters support it." In other words, you can't use caffeine to completely wipe out an entire week's worth of very late nights of studying, but you can use it to make yourself feel less bogged down by sleepy feelings in the morning.
These effects will vary, in length and strength of effect, from person to person, depending on genetics, other physiology factors, and tolerance. But more on that in a bit. What's important to take away is that caffeine is not as simple in effect as a direct stimulant, such as amphetamines or cocaine; its effect on your alertness is far more subtle.
The general consensus on caffeine studies shows that it can enhance work output, but mainly in certain types of work. For tired people who are doing work that's relatively straightforward, that doesn't require lots of subtle or abstract thinking, coffee has been shown to help increase output and quality. Caffeine has also been seen to improve memory creation and retention when it comes to "declarative memory," the kind students use to remember lists or answers to exam questions.
(In a semi-crazy side note we couldn't resist, researchers have implied this memory boost may be tied to caffeine's effect on adrenaline production. You have, presumably, sharper memories of terrifying or exhilarating moments in life, due in part to your body's fight-or-flight juice. Everyone has their "Where I was when I heard that X died" story, plugging in John F. Kennedy, John Lennon, or Kurt Cobain, depending on generational relatability).
Then again, one study in which subjects proofread text showed that a measurable boost was mainly seen by those who could be considered "impulsive," or willing to sacrifice accuracy and quality for speed. And the effect was only seen in morning tests, indicating the subjects may have either become lightly dependent on caffeine, or were more disposed to such tasks at that time of day.
So when it comes to caffeine's effects on your work, think speed, not power. Or consider it an unresolved question. If we're only part of the way to understanding how caffeine affects the brain, we're a long way to knowing exactly what kind of chemicals or processes are affected when, say, one writes a post about caffeine science one highly caffeinated afternoon.
For a more direct look at what happens to your brain when there's caffeine in your system, we turn to the the crew at Current. They hooked up one of their reporters to a brain monitor while taking on some new caffeine habits, and share their brains on caffeine:
Why do so many patients coming out of anesthesia after major surgery feel a headache? It's because, in most cases, they're not used to going so long without coffee. The good news? If they wait a few more days, they can start saving coffee again for when they really need it.
The effectiveness of caffeine varies significantly from person to person, due to genetics and other factors in play. The average half-life of caffeine—that is, how long it takes for half of an ingested dose to wear off—is about five to six hours in a human body. Women taking oral birth control require about twice as long to process caffeine. Women between the ovulation and beginning of menstruation see a similar, if less severe, extended half-life. For regular smokers, caffeine takes half as long to process—which, in some ways, explains why smokers often drink more coffee and feel more agitated and anxious, because they're unaware of how their bodies work without cigarettes.
Caffeine, it's been suggested, is probably not directly responsible for all these changes. By keeping your brain from using its normal "I'm tired" sensors, though, your caffeine may be causing the brain to change the way all of its generally excitable things are regulated. Your next venti double shot goes a little less far each time, in any case. Photo by zoghal.
A 1995 study suggests that humans become tolerant to their daily dose of caffeine—whether a single soda or a serious espresso habit—somewhere between a week and 12 days. And that tolerance is pretty strong. One test of regular caffeine pill use had some participants getting an astronomical 900 milligrams per day, others placebos—found that the two groups were nearly identical in mood, energy, and alertness after 18 days. The folks taking the equivalent of nine stiff coffee pours every day weren't really feeling it anymore. They would feel it, though, when they stopped.
You start to feel caffeine withdrawal very quickly, anywhere from 12 to 24 hours after your last use. That's a big part of why that first cup in the morning is so important—it's staving off the early effects of withdrawal. The reasons for the withdrawal are the same as with any substance dependency: your brain was used to operating one way with caffeine, and now it's suddenly working under completely different circumstances, but all those receptor changes are still in place. Headaches are the nearly universal effect of cutting off caffeine, but depression, fatigue, lethargy, irritability, nausea, and vomiting can be part of your cut-off, too, along with more specific issues, like eye muscle spasms. Generally, though, you'll be over it in around 10 days—again, depending on your own physiology and other factors.
Update: Commenter microinjectionist offers his own summary of more recent caffeine studies, which offers expanded reasons why caffeine users feel a "morning crash," as well as why your whole body, not just your brain, might feel so bad when you withdraw.
Beyond the equivalent of four cups of coffee in your system at once, caffeine isn't giving you much more boost—in fact, at around the ten-cup level, you're probably less alert than non-drinkers. So what if you want to start getting a real boost from caffeine once again, in a newly-learned, less-dependent way?
Braun, author of Buzz, sees it the same way, but still uses coffee—strategically, according to our email exchange:
In practical terms, this means that if you'd like to be able to turn to caffeine when you need it for a quick, effective jolt, it's best to let your brain "dry out" for at least several days prior to administration. This is actually my current mode of consumption. I don't regularly drink coffee anymore (gasp).
This from a man who loved (and wore out) his home espresso maker. I love coffee in all its guises. But after 30+ years it wasn't working for me. For one thing, the problem with caffeine is that there are adenosine receptors all over the body, including muscles. For me, that meant that caffeine made me vaguely stiff and sore, and it aggravated a tender lower back that was prone to spasm. But I also just wasn't getting a clean, clear buzz from coffee...I drank so much, so regularly, that drinking an extra cup or two didn't do a helluva lot except, perhaps, make me a little more irritable.
So about a year ago I slowly tapered down, and now I have, if anything, a cup of tea (half black, half peppermint) in the morning. (The amount of caffeine from the black tea isn't enough to wire a gnat.) Not only does my body feel better now, my brain is clean of caffeine, so I really want (or need) a good neural jump-start, I will freely...nay, ecstatically...indulge. Then I stop and let the brain settle again.
That's the theory, anyway...and it's basically true, although I'll freely admit that sometimes I have an espresso or coffee just because it tastes so damned good.
If you'd like Braun's extended takes on caffeine tolerance and withdrawal, along with the advent of energy drinks and caffeine's impact on creativity, you can read our full email interview.
