Wednesday, December 30, 2009
Monday, December 28, 2009
Saturday, December 26, 2009
Friday, December 25, 2009
Wednesday, December 23, 2009
Tuesday, December 22, 2009
Sunday, December 20, 2009
Saturday, December 19, 2009
Thursday, December 17, 2009
Tuesday, December 15, 2009
Monday, December 14, 2009
Ready to Exercise? Check Your Watch
By GINA KOLATA
Published: December 9, 2009
MY friend Jen Davis and I often run together in the morning because it can be easier to fit in a run before work than after. But we always thought we ran better in the evening.
Then I accidentally discovered something weird. I took a spinning class one Thursday night, and my heart rate, measured by a monitor strapped around my chest, soared. I don't usually use a heart-rate monitor, but with stationary bikes, heart rate is pretty much the only way to know how hard you are working. And that night, my high heart rate told me it really was a tough workout.
The next morning I did a workout in my garage on a trainer — a device that holds a road bike, turning it into a stationary bike and yet allowing you to use its gears. My heart rate was about 15 beats a minute lower than it had been the night before. It seemed like a pitiful workout.
So the next night I got on the trainer again. I had the same playlist (I use music to set my cadence). I used the same gears for each song. And during the hourlong workout, my average heart rate and my maximum heart rate were about 15 beats a minute higher than they'd been the morning before.
I tried again the next morning. My heart rate was low. Intrigued, I tried my experiment for a week, alternating between early morning and early evening workouts. I got really sick of that playlist, but I wanted to control every variable.
And the pattern persisted: high heart rate at night, low in the morning for the identical workout. Once I even tried the workout in midday — that time, my heart rate was in between.
Could it be that I actually was a more efficient athlete in the morning, doing the same work but with less effort, as measured by a lower heart rate?
Jen reminded me that we'd seen the heart-rate effect last year but had not appreciated it. I had a stress fracture and was confined to pool running, which involves sprinting in the deep end of a pool. Your feet never touch the bottom. It was hard to gauge how hard we were working, so Jen and I wore heart rate monitors, just as we do in spinning classes.
We did the pool workouts together, and neither of us got our heart rates as high as we wanted in the morning. Evenings were fine, though. We thought we were just sluggish in the morning.
I also asked some friends who use heart rate monitors if they'd noticed anything like what I'd experienced.
Tara Martin, a triathlete, said she could never get her heart rate up in the morning.
Richard Friedman, a swimmer, said his heart rate was always lower in the morning. His swim team does the same workout in the morning as in the evening, and he swims it just as fast. He had assumed that somehow he was just not putting in the same effort early in the day. "Still," he said, "I'm pretty energetic all the time."
I asked Dr. William Haskell, an exercise researcher and emeritus professor of medicine at Stanford, if I'd stumbled on a known fact about heart rates. But he was baffled. Maybe I didn't have caffeine in the morning? So I tried taking NoDoz before the next morning workout. It made no difference.
Dr. William Roberts, a former president of the American College of Sports Medicine and a family physician at the University of Minnesota, said it was a "tough question." He added, "I do not have a good physiologic explanation for the phenomenon you are describing."
But, it turns out, a small group of researchers has studied the question of exercise performance and time of day, even doing studies of heart rates. And not only are performances better in the late afternoon and early evening, but, contrary to what exercise physiologists would predict, heart rates are also higher for the same effort.
One recent study, by the late Thomas Reilly and his colleagues at the Research Institute for Sport and Exercise Sciences at Liverpool John Moores University in England, found that people's maximum heart rates and sub-maximal heart rates were lower in the morning but that their perception of how hard they were working was the same in the morning as it was later in the day.
Dr. Reilly and his colleague Jim Waterhouse, in a review published this year, also noted that athletes' best performances, including world records, were typically set in the late afternoon or early evening.
Greg Atkinson, also at Liverpool John Moores University, said that some researchers, noticing that heart rates during exercise were lower in the morning, reasoned the way I did — that people must be more efficient in the morning. It would mean that exercise was easier in the morning. Of course, it seemed harder to me, but I could have been deluding myself. Not really, Dr. Atkinson said. It actually is harder to exercise in the morning.
"Most components (strength, power, speed) of athletic performance are worst in the early hours of the morning," he wrote in an e-mail message. "Ratings of perceived exertion during exercise have generally been found to be highest in the early morning."
If you exercise later in the day, your muscles are more flexible and stronger and your heart and lungs are more efficient, said Michael H. Smolensky, an expert in chronobiology, the study of the body clock.
"Is a heart rate of 140 in the morning indicative of the same level of workout cost as in the afternoon?" asked Dr. Smolensky, a visiting professor at the University of Texas Health Sciences Center in Houston.
"I would say no," he added. "Exercise physiologists say you should be able to perform at the same level with a heart rate of 140 in the morning as in the afternoon or early evening. But chronobiologists say your capacity to generate and tolerate a higher heart rate is better later in the day."
"In the afternoon and evening," Dr. Smolensky said, "you are in a different biological state."
But, he added, all this applies to people who are regular exercisers, who work out vigorously three or more times a week. People who are not regular exercisers, Dr. Smolensky said, put much more strain on their hearts in the morning, making their heart rates higher then.
In fact, Dr. Smolensky added, people at risk for a heart attack should plan their workouts for late afternoon or early evening.
But if you are used to regular exercise, is it better to train in the early evening?
"I really don't know the answer," Dr. Smolensky said.
"My personal approach is to train when your biological efficiency is greatest, which means late afternoon or early evening for most people," he said. "Others say if you train when your biological efficiency is least you will get a harder workout."
Some elite athletes prefer morning workouts for reasons that have nothing to do with research studies.
Deena Kastor, who holds the American marathon record, said her former coach and mentor, Joe Vigil, insisted on morning workouts. He told her that there was more fluid between the vertebrae of the spine after a night in bed, Ms. Kastor said. And, she said, "fluid made your spine more forgiving and more able to absorb the pounding of running." She noted that she had been running in the morning for the last 13 years "with very little injury."
But when people compete, if, for example, they want a personal best time, they might want to seek out one of the few events that start late in the day. Or, even better, it might make sense for endurance events, like marathons, to start in the afternoon instead of the morning, when they almost always are held. Maybe they could be held later in the year, to avoid afternoon heat.
Dr. Smolensky agreed.
"Most marathons start early under the guise that it's cooler then," he said. "That needs to be looked at."
Sunday, December 13, 2009
Saturday, December 12, 2009
Thursday, December 10, 2009
Wednesday, December 9, 2009
The science: Human movement occurs on three different geometric planes:
1. The sagittal plane, for front-to-back and up-and-down movements
2. The frontal plane, for side-to-side movements
3. The transverse plane, for rotational movements
Most weight-lifting movements—the bench press, squat, curl, lunge, and chinup, to name a few—are performed on the sagittal plane; the balance of exercises—for instance, the lateral lunge and side bend—occur almost entirely on the frontal plane. This means that most men rarely train their bodies on the transverse plane, despite using rotation constantly in everyday life, as well as in every sport. Case in point: walking. It's subtle, but your hips rotate with every step; in fact, watch a sprinter from behind and you'll see that his hips rotate almost 90 degrees. By adding a rotational component to any exercise, you'll automatically work more muscle—since you'll fully engage your core, as well as the original target muscles—and simultaneously build a better-performing body.
Apply it: Simply twist your torso to the right or left in exercises such as the lunge, situp, and pushup. You can also rotate your hips during movements such as the reverse crunch.
The science: When you lower your body during any exercise, you build up "elastic energy" in your muscles. Just like in a coiled spring, that elasticity allows you to "bounce" back to the starting position, reducing the work your muscles have to do. Eliminate the bounce and you'll force your body to recruit more muscle fibers to get you moving again. How? Pause for 4 seconds in the down position of an exercise. That's the amount of time it takes to discharge all the elastic energy of a muscle.
Apply it: Use the 4-second pause in any exercise. And give yourself an extra challenge by adding an explosive component, forcefully pushing your body off the floor—into the air as high as you can—during a pushup, lunge, or squat. Because you're generating maximum force without any help from elastic energy, you'll activate the greatest number of muscle fibers possible.
Tuesday, December 8, 2009
Mark A W Andrews
Muscle cramping is a common problem encountered by athletes and nonathletes
alike. Defined as painful involuntary skeletal muscle contractions, cramps
may be categorized as either nonexercise related or exercise related. The
etiology of the former group may involve hormonal, electrolyte or metabolic
imbalances, or it may result from long-term medication. Diagnostic medical
testing may be required if cramps are a persistent problem. Exercise-related
muscle cramps (ERMC) are much more common. They typically affect the large
muscles of the legs during or immediately after exercise and last for seconds
to a few minutes. These are typically benign but result in intense pain and
may not seem innocuous at the time.
There is little definitive knowledge of the etiology of ERMC. Traditionally,
such cramping was believed to arise from dehydration, electrolyte imbalances
(including magnesium, potassium and sodium), accumulation of lactic acid, or
low cellular energy levels. These proposals, however, have been shown to have
minimal scientific value.
More recent developments indicate that the cause of cramps most likely
involves hyperactivity of the nerve-muscle reflex arc. In this scheme, some
of the normal inhibitory activity of the central nervous system (CNS)
reflexes is lost as a result of CNS fatigue or overuse of feedback
communication with muscles. These spinal reflexes use two receptors, known as
Golgi tendon organs and muscles spindles, found in skeletal muscles. Golgi
tendon organs may become inhibited and muscles spindles can become
hyperactive, leading to sustained activation of the muscle.
It has been suggested that prolonged sitting, poor or abnormal posture or
inefficient biomechanics (all of which may be related to poor flexibility)
predispose these reflexes to malfunctioning. Age also seems to predispose
individuals to cramping--the phenomenon may develop later in life for people
who exercise for years without prior problems. Other factors include
increased body weight and improper footwear. Eccentric muscle contraction and
other musculoskeletal injuries can contribute to the problem.
If a muscle's hyperexcitability is the basis of cramping, then stretching
should attenuate the response. In evidence, it is well recognized that, once
induced, stretching the affected muscle can ameliorate cramping. Stretches
should be held for 15 to 30 seconds or until the muscle relaxes and the cramp
does not recur when the muscle is returned to its normal relaxed position. In
addition, once cramping starts, exercise should be curtailed for at least an
hour, which allows the muscles and the CNS to recover. It is never a good
idea to "run through" these cramps. Applying heat to the area for a few
minutes while stretching may also help the muscle.
Prophylactic stretching of the major muscles of the lower limbs for at least
five to 10 minutes during warm-up and cool-down periods can help prevent
cramps. The importance of flexibility cannot be overstated, particularly for
older athletes. Other recommendations include minimizing running hills and
stairs (limiting eccentric contractions); undergoing a biomechanical
evaluation of your exercise technique; making sure shoes and other equipment
are appropriate and not excessively worn. If, after a few months, cramps do
not respond to these measures, see a qualified sports physician or physical
Sunday, December 6, 2009
Saturday, December 5, 2009
Thursday, December 3, 2009
Phys Ed: How to Prevent Stress Fractures
By GRETCHEN REYNOLDS
Stress fractures are one of the more pernicious injuries in sports, afflicting the experienced and the aspiring, with no regard for competitive timing. Last year, Tiger Woods managed to win the U.S. Open despite suffering from stress fractures in his left leg (as well as other leg and knee injuries), while the great British marathoner Paula Radcliffe struggled through the Beijing Olympics Marathon on a leg barely recovered from a stress fracture, one of several she’s suffered. The International Association of Athletics Federations, the world governing body for track and field, recently described stress fractures, with a kind of grim resignation, as “the curse of athletes.”
But studies published in this month’s issue of the journal Medicine & Science in Sports & Exercise offer hope that, at least for runners, simple alterations in their stride or in the strength of their legs might reduce their risk for the most common type of stress fracture.
In one of the studies, undertaken at the University of Minnesota, researchers recruited 39 competitive women runners, ages 18 to 35, and started measuring them. In particular, the scientists wanted to examine the size and shape of their shinbones, or tibias. About half of all stress fractures occur in the tibia, studies show. When you run or jump, that bone is pulled and bent. Sometimes, microscopic fissures form. In most cases, these tiny cracks heal quickly. But, sometimes, continued activity overwhelms the bone’s capacity to recover. The cracks grow and combine into a fracture.
The Minnesota researchers wanted to see whether the shinbones of the runners with a history of stress fractures were weaker than those without. Earlier studies suggested that this would be the case. But few studies have examined the size of the runners’ calf muscles. Bones tend to adapt to the muscles around them; puny muscles can mean puny bones. The Minnesota scientists, using a new machine that examines bone in three dimensions and measuring the runners’ leg muscles, found that, surprisingly, the injured runners’ bones were as strong, in relation to their muscle size as the bones in the uninjured runners. But the injured runners had significantly smaller calf muscles and therefore also slighter bones. The primary difference, the researchers concluded, between the women who suffered stress fractures and those who hadn’t was the size (and presumably strength) of their calf muscles.
This finding should be encouraging to anyone who has had a tibial stress fracture or would prefer not to. “It does seem as if strengthening the calf muscles may be a very easy way” to reduce fracture risk, says Moira Petit, an associate professor of kinesiology at the University of Minnesota and an author of the study. In addition, she said, “our data suggest that you don’t have to strengthen the muscle by much.” A small increase of bulk, achievable by, for instance, rising up on to your toes and sinking back to the floor 10 or 12 times every day, might be enough. Adding even a small amount of calf muscle “serves two purposes,” Ms. Petit says. First, “the strength of the bone will usually increase” in response to the added muscle. And, as a bonus, the new muscle “can absorb more” of the forces generated when you run. So even as the tibia strengthens in response to the new muscle, it also is subjected to less shock. “Really, there’s no downside to this,” Ms. Petit says.
Her results, though, may apply primarily to women; she’s studying male runners, but so far, she says, isn’t seeing the same relationship between their calf-muscle size and bone strength. The other study in the current Medicine & Science in Sports & Exercise, however, did focus on men and their stress fractures, although, in this case, the lead researcher suggests that the findings would be true in women as well. In the work, from Iowa State University in Ames, computer modeling was used to predict what would happen to stress fracture risk if runners changed their strides. The researchers attached reflective markers to the bodies of 10 former or current collegiate-level cross-country runners and had them run repeatedly down a runway nearly 30 meters long, making sure to step onto a force plate that measured how hard they were striking the ground. During successive runs, the men were asked to shorten their natural strides, while maintaining their pace. The scientists entered the data into computer programs that calculated just how much force was being applied to the shinbone under different striding conditions. The researchers determined that reducing stride length by about 10 percent seemed to reduce the stress on the tibia enough to lower the risk of a stress fracture.
Why, though, should shortening your stride affect your tibia at all? “Think of it this way,” says Brent Edwards, lead author of the study and now a post-doctoral research fellow in the Department of Kinesiology and Nutrition at the University of Illinois, in Chicago. “If you spend less time in the flight phase of running” — meaning in the air — “you’ll hit the ground with less force.” On the other hand, you’ll hit the ground more often. But in Mr. Edwards’s models, the reduction in pounding from an abbreviated stride outweighed the shock from a few additional strides per mile.
Even for those of us without a biomechanical expert in the house, gauging a 10 percent reduction in stride is not difficult, Mr. Edwards says. “Ten percent is about as much as you can shorten your stride without it beginning to feel quite uncomfortable,” he says. And absolute precision isn’t necessary. “Seven or eight or nine percent is fine,” he says.
Neither Ms. Petit nor Mr. Edwards suggests, of course, that any, single prevention approach will end all tibial stress fractures. “There are so many elements involved,” Ms. Petit says. Training, hormones, genetics, diet and shoe choice probably all play a role. “But if there’s something easy and benign that you can do to lessen the risk,” she asks, “why not?”