Isegoria

It says something about our society that Slate‘s “explainer” has to explain why there are so few dunks in women’s basketball:

Leaping ability. The average WNBA player, at just under 6 feet, is about 7 inches shorter than her male counterpart. (Average data for all collegiate female players isn’t available.) Height is only part of the problem, though — plenty of 6-foot male players can dunk. The gender gap in vertical leaping ability is also substantial. The average female college basketball player has a vertical leap of approximately 19 inches, compared with more than 28 inches for the average male player. Since you have to get your fingers about 6 inches above the rim to have a chance at dunking, a female player of average leaping ability would have to be around 6-foot-6 with a standing reach of 8-foot-11”—the approximate measurements for Michael Jordan. (His Airness reportedly had a 48-inch vertical leap.) Few female players are that tall, and none of those giants is an exceptional leaper.

Still, the paucity of dunks during women’s games gives a slightly false impression of female dunking ability. Dunking in practice is somewhat more common, but many coaches advise against attempting a rim-rattler when it counts because of the risk of injury or throwing away an easy deuce. The late Oklahoma State coach Kurt Budke, for example, forbade forward Toni Young from dunking after she broke her arm in three places while completing one during practice in 2011.

The gender gap in leaping ability is wide at every level of competition. According to a 2004 study of medical students and their spouses, the average male in his 20s can out-jump 95 percent of females in the same age group. And men seem to have a peculiar advantage in jumping compared with other athletic pursuits. According to a study of world records for track and field events as of 2004, men had a 15 to 16 percent advantage (PDF) in high jump, long jump, and triple jump. The gender gap in running events was only 10 to 13 percent. (Pole vault featured the biggest difference at 23 percent, but that’s likely because women have participated in that sport at the Olympic level only since 2000.) The difference between men and women has been relatively stable since 1983.

When active volunteers tried being not-so-active, their blood-sugar levels spiked after they ate:

Exercise guidelines from the American Heart Association and other groups recommend that, for health purposes, people accumulate 10,000 steps or more a day, the equivalent of about five miles of walking. Few people do, however. Repeated studies of American adults have shown that a majority take fewer than 5,000 steps per day.

The Missouri volunteers were atypical in that regard. Each exercised 30 minutes or so most days and easily completed more than 10,000 daily steps during the first three days of the experiment. The average was almost 13,000 steps.

During these three days, according to data from their glucose monitors, the volunteers’ blood sugar did not spike after they ate.

But that estimable condition changed during the second portion of the experiment, when the volunteers were told to cut back on activity so that their step counts would fall below 5,000 a day for the next three days. Achieving such indolence was easy enough. The volunteers stopped exercising and, at every opportunity, took the elevator, not the stairs, or had lunch delivered, instead of strolling to a cafe. They became, essentially, typical American adults.

Their average step counts fell to barely 4,300 during the three days, and the volunteers reported that they now “exercised,” on average, about three minutes a day.

Meanwhile, they ate exactly the same meals and snacks as they had in the preceding three days, so that any changes in blood sugar levels would not be a result of eating fattier or sweeter meals than before.

And there were changes. During the three days of inactivity, volunteers’ blood sugar levels spiked significantly after meals, with the peaks increasing by about 26 percent compared with when the volunteers were exercising and moving more. What’s more, the peaks grew slightly with each successive day.

This change in blood sugar control after meals “occurred well before we could see any changes in fitness or adiposity,” or fat buildup, due to the reduced activity, Dr. Thyfault says. So the blood sugar swings would seem to be a result, directly, of the volunteers not moving much.

People are obese, because they can’t stop eating, because they really enjoy eating — or do we have it all backwards?

According to a new study from Kyle Burger and Eric Stice at the Oregon Research Institute, those who overeat may actually get less pleasure from food. So they’re forced to consume larger quantities (and added calories) to achieve an equivalent reward.

The researchers began by asking 151 adolescents about eating habits and food cravings. Then, they stuck the teens in a brain scanner while showing them a picture of a milkshake followed by a few sips of the real thing. They were particularly interested in looking at the response of the dopamine reward pathway in the brain, a cortical network responsible for generating the pleasurable emotions triggered by pleasurable things.

By comparing the response of the reward pathway to the eating habits of the adolescents, the scientists were able to show that those who ate the most ice cream showed the least activation in their reward areas when consuming the milkshake. This suggests that they were eating more in desperate compensation, trying to make up for their indifferent dopamine neurons. People crave pleasure, and they don’t stop until they get their fill, even if means consuming the entire pint of Häagen-Dazs.

This research builds on previous work by Dr. Stice documenting the dangerous feedback loop of overeating. Although people struggling with obesity tend to have less-responsive reward pathways—they even have fewer dopamine receptors—overeating makes the problem worse, further reducing the pleasure from each bite. Like an alcoholic who needs to consume ever-larger quantities of liquor to achieve the same level of intoxication, individuals with “hypofunctioning reward circuits” are forced to eat bigger portions in search of the same level of satisfaction. It’s an addiction with diminishing returns.

It’s an addiction with diminishing returns.

Harvard University’s men’s and women’s distance running squads track their injuries. A recent study examined four years’ data and found that foot form explains running injuries rather well:

No one is always a forefoot striker or a heel striker. Your form depends on many factors, including your speed, the terrain, whether you’re tired and so on. But most of us have a predominant strike pattern, and so it was with the 52 Harvard runners. Thirty-six, or 69 percent of them, were heel strikers, while 16, or 31 percent, were forefoot strikers. The proportions were similar regardless of gender.

More interesting was the distribution of injuries. About two-thirds of the group wound up hurt seriously enough each year to miss two or more training days. But the heel strikers were much more prone to injury, with a twofold greater risk than the forefoot strikers.

This finding, the first to associate heel striking with injury, is likely to fuel the continuing and not-always civil debate about whether barefoot running is better. (It hurts to hit the ground with your heel if you’re not wearing shoes.)

A recent Irish study demonstrated that a strenuous ride on an exercise bike could improve memory, and blood samples taken during the experiment show how exercise benefits the brain:

Immediately after the strenuous activity, the cyclists had significantly higher levels of a protein known as brain-derived neurotrophic factor, or BDNF, which is known to promote the health of nerve cells. The men who had sat quietly showed no comparable change in BDNF levels.

In humans (and other animals) certain steroid hormones, like testosterone, are both anabolic (tissue-building) and androgenic (masculinizing). For years, the goal of ergogenic-drug researchers was to produce an anabolic drug without androgenic side-effects.

New research shows that plant brassinosteroids are anabolic in rats, without androgenic side-effects:

Brassinosteroids are plant-derived polyhydroxylated derivatives of 5a-cholestane, structurally similar to cholesterol-derived animal steroid hormones and insect ecdysteroids, with no known function in mammals. 28-Homobrassinolide (HB), a steroidal lactone with potent plant growth-promoting property, stimulated protein synthesis and inhibited protein degradation in L6 rat skeletal muscle cells (EC50 4 ?M) mediated in part by PI3K/Akt signaling pathway. Oral administration of HB (20 or 60 mg/kg/d for 24 d) to healthy rats fed normal diet (protein content 23.9%) increased food intake, body weight gain, lean body mass, and gastrocnemius muscle mass as compared with vehicle-treated controls. The effect of HB administration increased slightly in animals fed a high-protein diet (protein content 39.4%).

Both oral (up to 60 mg/kg) and subcutaneous (up to 4 mg/kg) administration of HB showed low androgenic activity when tested in the Hershberger assay. Moreover, HB showed no direct binding to the androgen receptor in vitro.

HB treatment was also associated with an improved physical fitness of untrained healthy rats, as evident from a 6.7% increase in lower extremity strength, measured by grip test. In the gastrocnemius muscle of castrated animals, HB treatment significantly increased the number of type IIa and IIb fibers and the cross-sectional area of type I and type IIa fibers.

These findings suggest that oral application of HB triggers selective anabolic response with minimal or no androgenic side-effects and begin to elucidate the putative cellular targets for plant brassinosteroids in mammals.

Expect to see BrassinoMax advertised in the muscle mags in 3… 2… 1…

A little deception helps push athletes to the limit:

In a new study, Dr. Thompson tried to find what that limit is.

He used the same method as before: Cyclists on stationary bikes raced an on-screen avatar going a bit faster than the cyclist’s own best time. In one group, the only variable was competition. Cyclists were told that the avatar would be going 2 percent faster or 5 percent faster than the cyclist had ever gone.

The other group was deceived. Each cyclist was told to compete against an avatar that would be moving as fast as that athlete had in his best effort. Actually, the avatar was programmed to race 2 percent harder or 5 percent harder. (A 5 percent increase in power translates into a 2 percent increase in speed, Dr. Corbett said.)

The cyclists in the first group gave up from the start when they knew the avatar would be moving faster than they ever had — even when the avatars were going 2 percent harder than the cyclists’ own best times. Instead, the athletes matched their own best efforts.

As had been observed in previous experiments, cyclists in the second group, who were deceived, kept up with their avatars when they were programmed to perform 2 percent harder than each athlete at his best. But 5 percent was just too much: The athletes kept up for about half the race, then gave up.

In the end, their overall pace was no better than it had been in their best effort without the avatar. Some seemed to do even worse than their previous best effort.

“It comes back to the belief system within the athlete,” Dr. Thompson said. Within limits, if an athlete thinks a certain pace is possible, he or she can draw on an energy reserve that the brain usually holds in abeyance.

One lesson, Dr. Thompson said, is that coaches can eke better performances out of athletes by means of small deceptions.

When an athlete has reached a plateau, a coach might tell an athlete in a training session that the course distance is slightly shorter than it actually is, for example, or that his or her speed at each interval is slightly slower than it is.

The new research suggests that this strategy may bring about an increase in performance, and Dr. Thompson said that it has been used to coach elite middle-distance athletes, although he declined to provide details.