Archive for November 19, 2007

Dehydration is directly linked to a decline in performance on the basketball court, according to a study published recently in Medicine & Science in Sports & Exercise®, the official journal of the American College of Sports Medicine (ACSM).

The study examined 17 males aged 17-28, and tested performance during basketball drills at various levels of dehydration (up to 4 percent). As dehydration increased, skill performance decreased, indicating that proper hydration is necessary for peak performance on the court.

“The study supports the notion that players should be given adequate opportunities to hydrate themselves during play and practice,” said Lindsay B. Baker, Ph.D. candidate, Pennsylvania State University, and lead author of the study.

Study participants completed three hours of interval treadmill walking, either with or without hydration. After a 70-minute rest period, subjects then performed a series of continuous basketball drills designed to simulate a fast-paced game. These included basketball-specific movement exercises (e.g., sprinting, defensive slides, and jumping) and shooting drills from various spots on the court (e.g., the free throw and three-point lines). Hydrated test subjects were given either flavored water or a carbohydrate-electrolyte sports drink.

The test results showed that:

— Subjects who were dehydrated by at least two percent consistently performed basketball movement exercises at slower rates.
— Dehydrated subjects failed to make as many shots as hydrated players.
— There was no difference in performance between hydrated subjects given flavored water or a carbohydrate-electrolyte drink.

Previous studies on NBA basketball players have shown significant lack of hydration, with an average of only about 40 percent of fluid losses from sweat replaced during practices or games.

“Many times the outcome of a basketball game is decided in the final minutes, when players tend to be the most dehydrated,” Baker said. “It’s crucial for basketball coaches at any level to be sure that their players are drinking adequate fluids during games and workouts to help prevent dehydration and attain peak performance.”

In February 2007, ACSM issued the Position Stand “Exercise and Fluid Replacement,” which provides insight on how to properly hydrate before, during, and after exercise. View the position stand here .

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National, and Regional members are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Communications and Public Information
American College of Sports Medicine

Advertisements

Taking a break in the middle of your workout may metabolize more fat than exercising without stopping, according to a recent study in Japan. Researchers conducted the first known study to compare these two exercise methods—exercising continually in one long bout versus breaking up the same workout with a rest period. The findings could change the way we approach exercise. Who wouldn’t want to take a breather for that”“Many people believe prolonged exercise will be optimal in order to reduce body fat, but our study has shown that repetitions of shorter exercise may cause enhancements of fat mobilization and utilization during and after the exercise. These findings will be informative about the design of [future] exercise regimens,” said lead researcher Kazushige Goto, Ph.D. “Most people are reluctant to perform a single bout of prolonged exercise. The repeated exercise with shorter bouts of exercise will be a great help [in keeping up with fitness].”

This finding is part of a study entitled Enhancement of fat metabolism by repeated bouts of moderate endurance exercise, found in the June 2007 edition of the Journal of Applied Physiology, which is published by the American Physiological Society. It was conducted by Kazushige Goto, of both the Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Tokyo, Japan and the Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark; Naokata Ishii, of the Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Tokyo, Japan; and Ayuko Mizuno and Kaoru Takamatsu, both of the Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.

Summary of Methodology

The researchers used seven healthy (avg. body mass: 66.1, percentage fat: 17.6) men with an average age of 25 who were physically active and familiar with exercise and had them perform three separate trials:

  • one single bout of 60-min exercise followed with a 60-min recovery period (Single)
  • two bouts of 30-min exercise with a 20-min rest after the first 30-min bout, along with a 60-min recovery period at the end (Repeated)
  • one 60-min rest period (Control)

The men performed each trial at the same time of day after fasting overnight. They exercised on a single ergometer (cycling machine) at the commonly recommended exercise prescription of 60% maximum oxygen intake. The recovery and rest periods were conducted while the subjects sat in chairs. Blood samples were taken every 15 minutes during the exercise and every 30 minutes during the recovery period. Their respiratory gas and heart rates were monitored continuously throughout the trial.

Summary of Results

The Repeated trial showed a greater amount of lipolysis (fat breakdown) than did the Single trial. This Repeated trial also had a pronounced increase in free fatty acids and glycerol (chemical compounds that are released when stored fat is used) concentrations in the final 15 minutes of exercise, whereas these concentrations only progressively increased throughout the Single trial. Also, the second half of the Repeated trial showed a significantly greater epinephrine response while also having a rapid decrease in insulin concentration as a result of lower plasma glucose. This combination of high epinephrine and low insulin concentration may have also increased the lipolysis. There was also enhanced fat oxidation in the recovery period of the Repeated trial than in the Single trial, but this result may be because the free fatty acids concentration was already high before the recovery period.

Conclusions

The American College of Sports Medicine recommends moderate exercise for the duration of 45 to 60 minutes to ensure a sufficient amount of energy is depleted in obese individuals. This has caused a greater focus on extending exercise sessions in order to burn more fat. However, this study shows that this method may not be the most effective way to enhance fat metabolism, as splitting up a long bout of exercise with a rest period burns more fat than a continuous bout of exercise. This study could help with the practical application of implementing new exercise methods in order to better manage and control weight in individuals in the future. However, Goto and his team of researchers plan on conducting further studies in order to explore the results in a variety of exercise durations as well as in different types of individuals.

—————————-
Article adapted by MD Only Weblog from original press release.
—————————-

Contact: Celia Lee
American Physiological Society

Steroid use by a Major League Baseball slugger may produce only modest increases in muscle mass and bat and ball speed but still boost home run production by 50 percent or more, according to a new study by Tufts University physicist Roger Tobin.

Tobin, a specialist in condensed matter physics with a long-time interest in the physics of baseball, will publish his paper “On the potential of a chemical Bonds: Possible effects of steroids on home run production in baseball” in an upcoming issue of the American Journal of Physics.

As Tobin’s paper notes, Babe Ruth’s record of 60 home runs in a single season stood for 34 years until Roger Maris hit 61 homers in 1961. For the next 35 years, no player hit more than 52 home runs in one season. But between 1998 and 2006, players hit more than 60 home runs in a season six times. Barry Bonds hit 73 home runs in 2001 — topping Maris’ mark by an astonishing 20 percent.

According to Tobin, the explosion in home runs coincides with the dawn of the “steroid era” in sports in the mid-1990s, and that surge quickly dropped to historic levels in 2003, when Major League Baseball instituted steroid testing.

While the increase in home runs has been clouded by suspected use of performance-enhancing steroids, many have wondered why home-running hitting would be particularly vulnerable to performance enhancement. They have also asked if it is even physically and physiologically plausible that steroids could produce effects of the magnitude observed. The answer to both questions, says Tobin, is “yes.”

Home Runs Disproportionately Affected

“A change of only a few percent in the average speed of the batted ball, which can reasonably be expected from steroid use, is enough to increase home run production by at least 50 percent,” he says. This disproportionate effect arises because home runs are relatively rare events that occur on the “tail of the range distribution” of batted balls.

“In most any statistical distribution — of people’s heights, SAT scores, or how far baseballs are hit — there’s a large bump where most of the values fall, with the graph falling rapidly as you move away from that region in either direction toward the rarer values,” explains Tobin. “It’s a well-known statistical property of such distributions that a relatively small shift in the center point of the distribution can produce a much larger proportional change in the number of values well above or below the center. Because the distribution’s ‘tail’ is particularly sensitive to small changes in the peak and/or width, home run records can be more strongly affected by steroid use than other athletic accomplishments.”

Muscle Mass Boosts Bat and Ball Speed

Tobin reviewed previous studies of the effect of steroid use and concluded that muscle mass, the force exerted by those muscles and the kinetic energy of the bat could each be increased by about 10 percent through the use of steroids. According to his calculations, the speed of the bat as it strikes the pitched ball will be about 5 percent higher than without the use of steroids and the speed of the ball as it leaves the bat will be about 4 percent higher.

To determine the ultimate impact on home run production, Tobin then analyzed a variety of models for trajectory of the baseball, accounting for gravity, air resistance and lift force due to the ball’s spin. While there was considerable variation among the models, “the salient point,” he says, “is that a 4 percent increase in ball speed, which can reasonably be expected from steroid use, can increase home run production by anywhere from 50 percent to 100 percent.”

What About the Pitchers?

Tobin applied a similar, though less extensive, mechanical analysis to pitching and found that smaller impacts were possible. He calculated that a 10 percent increase in muscle mass should increase the speed of a thrown ball by about 5 percent, or four to five miles per hours for a pitcher with a 90 mile per hour fastball. That translates to a reduction in earned run average of about 0.5 runs per game.

“That is enough to have a meaningful effect on the success of a pitcher, but it is not nearly as dramatic as the effects on home run production,” says Tobin. “The unusual sensitivity of home run production to bat speed results in much more dramatic effects, and focuses attention disproportionately on the hitters.”

A Reasonable Suspicion

Tobin is quick to acknowledge that athletes in many sports today achieve at a higher level than athletes of the past, and that this trend is not evidence of cheating. He also points out that many other changes, including adjustments in ballpark dimensions, league expansions, entry of African-American athletes, and lowering of the pitcher’s mound, could affect major league batting — although he says that none of those changes coincide with the sudden burst of home run production in the mid-1990s.

“Physics cannot tell us whether a particular home run was steroid-assisted, or even whether an extraordinary individual performance indicates the use of illicit means,” says Tobin.

But analysis of the physics, combined with physiology, yields telling results. “These results certainly do not prove that recent performances are tainted, but they suggest that some suspicion is reasonable,” he concludes.

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the university’s schools is widely encouraged.

Source: Kim Thurler
Tufts University

A stunning discovery by German scientists may make blood doping and the treatment of severe anemia as easy as washing your hair.  

In the October print issue of The FASEB Journal (http://www.fasebj.org/), researchers show that the estimated 100,000 hair follicles on each person’s head have the potential to become erythropoietin (EPO) factories. EPO, the hormone primarily responsible for the creation of red blood cells, is used illegally to enhance athletic performance and is used legally to treat severe anemia associated with kidney failure and chemotherapy.

“The ultimate hope is that we’ll be able to up the production of natural EPO in our hair follicles whenever we need it, safely and at a low cost,” said Ralf Paus, senior author of the study. “Our study also highlights that ancient hormones are engaged in many more activities than conventional medical wisdom has assigned to them.”

Normally, EPO is created and released by the kidneys. When the kidneys fail, or when someone undergoes chemotherapy, this process is disrupted and severe anemia occurs. Today, most people are treated using synthetic EPO to bring red blood cells back to normal levels, but synthetic versions of this hormone are relatively expensive. Blood-doping athletes use synthetic EPO to help their bodies bring red blood cells to above-normal levels. This increased concentration of red blood cells allows the blood to deliver more oxygen to muscles than normal, significantly improving endurance and performance. The major danger in boosting the number of red blood cells above normal is that as the blood thickens with red blood cells, the possibility of heart attack increases.

“This study opens doors to an entirely new approach for treating EPO-related anemia,” said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. “The study also is important because it suggests that there is still much to learn about ‘well known’ processes in the body.”

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Source: Cody Mooneyhan
Federation of American Societies for Experimental Biology

The FASEB Journal (http://www.fasebj.org/) is published by the Federation of American Societies for Experimental Biology (FASEB) and is consistently ranked among the top three biology journals worldwide by the Institute for Scientific Information. FASEB comprises 21 nonprofit societies with more than 80,000 members, making it the largest coalition of biomedical research associations in the United States. FASEB advances biological science through collaborative advocacy for research policies that promote scientific progress and education and lead to improvements in human health.

It actually takes approximately twice as much time to take the elevator when ascending or descending one floor.  To test this, researchers at the University of South Carolina recorded the time required to ascend and descend one floor by taking the stairs and elevator over several days.  A small group of participants were instructed to alternate between elevator and stair use and to take the stairs at a self-selected “normal” pace during the course of their daily routine.

The time required to take the elevator was significantly greater than the time required to use the stairs going both up and down one floor. The excess time required when taking the elevator was attributed to the wait, not the travel time, since the actual elevator ride was measured at approximately 10 seconds.  The time required to ascend the stairs was greater than the time to descend the stairs, while there was no significant difference between taking the elevator up and elevator down one floor.

The study team hopes this information can be used as part of an intervention to increase stair use, where specific and relevant messages have been shown to be effective in encouraging physical activity.

“If climbing the stairs a few floors saves you time and adds to the physical activity you can accumulate throughout the day, it’s a win-win,” said researcher Joshua Westmeier-Shuh, lead author of the study.  “Let’s look first at shifting the perception that the elevator is a better choice when rushing to work or thinking about how to incorporate activity into the day, and then think about the implications this can have for worksite wellness.  Bottom line: stairs win.”

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Communications and Public Information
American College of Sports Medicine

The conclusions outlined in this news release are those of the researchers only, and should not be construed as an official statement of the American College of Sports Medicine.

Injuries occur to golfers of all ages and ability levels, and can significantly affect their golf game and daily life. Those who fail to warm up adequately appear to be putting themselves at greater risk of injury.

The survey involved 304 golfers, who revealed their golf activities, injury status and warm-up habits over a 12-month period. About a third of the golfers (111, or 36.5 percent) reported an injury, most frequently to the lower back, shoulder or elbow. Strains were by far the most commonly reported type of injury (37.8 percent). Other types of injuries included stiffness, inflammation, tendonitis, and sprains and, less commonly, pinched nerves, fractures, heel spurs and contusions or dislocations.

”Only a small percentage of golfers were shown to perform an appropriate warm-up prior to play or practice. The message isn’t getting across,” said Andrea Fradkin, lead author of the study.  “Golf professionals need to tell golfers to warm up, and not just hit balls.”

A full warm-up, she explained, consists of three components:
1. Aerobic exercise to increase muscle temperature
2. Sport-specific stretching (including stretching the shoulder, trunk, chest, lower back, hamstrings, forearm, and wrist)
3. Activity similar to the event, starting slowly and building in intensity (For golf, this might consist of air swings involving the club but not the ball)

Only three percent of golfers surveyed regularly performed two or more of the components, leaving them vulnerable to injury.

Fradkin and her colleagues noted that the frequency and types of injuries varied according to the golfers’ age and skill level. More experienced players—who play more often—tended to sustain more back injuries, while those with higher handicaps suffered more injuries to their hips, elbows and knees due to poor swing mechanics. Researchers noted that older golfers are likely to sustain more groin injuries due to a decrease in hip strength, and more knee and foot injuries due to degeneration of those joints.

According to Fradkin, this study underscored the results of her previous research into golfing injuries, while shedding new light. “This is the first study to look at the age, gender and handicap of injured golfers. Only two studies have looked retrospectively at injuries sustained over a 12-month period.”

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Communications and Public Information
American College of Sports Medicine

The conclusions outlined in this news release are those of the researchers only, and should not be construed as an official statement of the American College of Sports Medicine.

Golfers averaged more than 13,000 steps in walking to play 18 holes, and even those using carts logged more than 6,000 steps. Guidelines published by ACSM and others recommend walking 10,000 steps per day to maintain cardiovascular fitness and effectively control weight.

“This illustrates an enjoyable way to get the health benefits of walking,” said Cristina Sanders, lead researcher for the study, who presented the findings as part of her graduate work at the University of Colorado, Colorado Springs. “Some people play golf for 40 or 50 years, and it can be quite beneficial.” While previous studies have measured the energy expenditure of individual golfers, this study thought to be the first using pedometers.

Researchers asked golfers at three courses to wear a pedometer while they played 18 holes and noted their height, weight, and handicap. They also noted number of players in each subject’s group, whether he would walk or use a cart, and which tee box he played. After the round, researchers recorded how many steps each golfer walked.

“We had expected that golfers using a cart might take one-quarter as many steps as those who walked the course,” Sanders said. “We were surprised to find that, depending on the course, cart users logged up to half as many steps.” Measuring each course by GPS (global positioning satellite) allowed researchers to calculate minimum course distances, including tee-to-green, green-to-tee, and intermediate path point distances (bridges, paths around lakes, etc.) for each tee box on every hole. These minimum course distances averaged 25 percent longer than the published course playing distances.

Walking golfers and cart golfers took 13,145 +/- 1,736 steps and 6,280 +/- 1,428 steps, respectively. Interestingly, Sanders and her colleagues found no correlation between step count and the golfers’ height, handicap or tee box. Self-reported weight of walking golfers, though, averaged about 8.5 pounds less than that of golfers who used carts.

The golfers in Sanders’ study were all men. She proposed that future research include women, who often play from different tees.  Also of interest, she said, would be a large-scale look into golfers’ energy expenditure, accounting for the extra effort associated with carrying clubs or using pull carts.

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Communications and Public Information
American College of Sports Medicine