IU research at the American College of Sports Medicine conference
Editors: Dozens of researchers from Indiana University participated in the annual meeting of the American College of Sports Medicine in Seattle May 27-30. Below is a sample of some of the research.
FOR IMMEDIATE RELEASE
June 1, 2009
Caffeine's effect on exercise induced asthma symptoms
Assisted performance in elite swimming?
Rethinking age groups in youth sports
Maximizing benefits of high altitude training
Use of high speed accelerometers as a coaching tool
IDing exercise induced asthma and its severity without an exercise challenge
An Indiana University study found that the ingestion of caffeine within an hour of exercise can reduce the symptoms of exercise induced asthma (EIA). A large dose -- 9 milligrams of caffeine per kilogram of body weight -- was as effective as the use of an albuterol inhaler, which is commonly used to treat or prevent exercise-induced asthma. Smaller amounts of caffeine -- for example, 3 and 6 milligrams of caffeine per kilogram of body weight -- also reduced the wheezing, coughing and other symptoms of EIA. Timothy Mickleborough, an associate professor in the Department of Kinesiology and co-investigator of the study, said no additional benefit was found when caffeine was combined with an albuterol inhaler. Mickleborough and his research colleagues have been investigating the efficacy of a number of nutritional factors, and his research to date has shown that a diet high in fish oil and antioxidants and low in salt has the potential to reduce the severity of EIA and perhaps reduce the reliance on pharmacotherapy. This is especially important since prolonged use of daily medications can result in reduced effectiveness, and there is growing concern about the potential side effects of inhaled corticosteroid use.
- Background: The caffeine study involved 10 asthmatic subjects who also had EIA, in a randomized, double-blind double-dummy crossover study. They ingested 3, 6, or 9 milligrams of caffeine per kilogram of body weight or a placebo an hour before running on a treadmill. Pulmonary function tests were conducted 15 minutes before the a eucapnic voluntary hyperpnea challenge (a surrogate for an exercise challenge) and then again 1, 5, 10, 15 and 30 minutes afterward.
For someone weighing 150 pounds, 3 to 9 milligrams of caffeine per kilogram of body weight equals around 205 to 610 milligrams of caffeine. Earlier research has found that caffeine can reduce the symptoms of EIA. This study extends this earlier work and is the first to examine any synergistic effect of caffeine use along with an albuterol inhaler.
The study, "Comparative and Synergistic Effects of Caffeine and Albuterol on The Severity of Exercise-Induced Bronchoconstriction," was presented during the Respiratory Session on Friday, May 29. Co-authors include lead author Timothy A. VanHaitsma, now at the University of Utah; Martin R. Lindley, Loughborough University, United Kingdom; and David Koceja and Joel Stager, IU's Department of Kinesiology.
An analysis by Indiana University researchers of top Olympic swim times since 1972 has found that a bias was introduced resulting in swim times in 2008 that were much faster than predicted. Elite swimming is grappling with the issue of high-tech swimsuits, which many credit with an astounding number of world records set since the latest generation of suits was introduced in February 2008. The study does not identify what caused the bias but describes the statistical modeling that has successfully predicted swim times during the previous Olympics, aside from the Olympic Games in 1996, when times were slower than predicted. The average error in predictions for 2008 Olympic swim times was three to six times greater than the errors in previous Olympics, said Joel Stager, professor in the Department of Kinesiology and director of the Counsilman Center for the Science of Swimming. Stager said the first step is to identify whether swim performances are being affected. The next step is a philosophical question that the greater swimming community needs to answer. No new advances in swimming techniques or training can account for the improved time, Stager said, so technology, such as swimsuits, or pharmacology could be responsible. "Do we, as a community, want 'assisted performance?'" he asked.
- Background: The fastest eight male and female performances in Olympic swimming events from 1972 through 2004 were analyzed. Using the mean time across all years, a best-fit power curve was calculated for each swim event. According to the study, these equations were used to predict the finish times for the 2008 Olympics. A binomial test of statistical significance was used to test whether the year as a whole was above or below the prediction line. In 2008, 65 percent of the Olympic swim events were faster than predicted. For the previous five Olympics combined, only 9 percent of the events were faster.
The study, "Identification of Bias in the Natural Progression of Swim Performance," was presented during the Sport Science I Session. Co-authors include lead author Christopher L. Brammer and David A. Tanner, both from IU's Counsilman Center and Department of Kinesiology in the School of Health, Physical Education and Recreation.
Grouping youth athletes into multiyear age classifications is an attempt to level the competitive playing field and help athletes avoid injuries resulting from strength and size mismatches. Indiana University researchers say the current U.S. classification system for youth swimmers would be more effective if it stratified swimmers using a single age category, a common approach used in many other countries. "Here, every two years you discourage a whole lot of kids," said Joel Stager, professor in the Department of Kinesiology and director of the Counsilman Center for the Science of Swimming.
- Background: In the U.S., competitive youth swimming has four unisex age groups: 10 and under, 11- to 12-year-olds, 13- to 14-year-olds and 15-year-olds and older. Researchers examined the top swim times for these ages up to 21 years for the past three years in the 50-, 100- and 200-yard freestyle events. Significant differences in average times between all ages were found up to ages 13 and 14 for the girls, depending on the distance. For the boys, significant differences were found up to ages 15 and 16. Three homogeneous subsets were identified between the ages of 15 and 20 for women (15- to 16-year-olds, 16- to 18-year-olds and 17- to 20-year-olds). Three homogeneous subsets were found for men between the ages of 17 and 20 (17- to 18-year-olds, 18- to 19-year-olds and 19- to 20-year-olds).
Stager said researchers looked at various possible age groupings, and even grouping girls differently than boys, but decided a single-age classification would work best. "There is no reason to suppose," said Stager, "that this would not be true for other sports as well. Technological advances available today would make the sorting of times at swim meets and other athletic events easily manageable, as well." The study, "Age Classification in USA Swimming: Are Current Competitive Age Groups Appropriate?" was presented during the Sport Science I Session. Co-authors include lead author Kosuke Kojima and Christopher L. Brammer, also from the Department of Kinesiology in IU's School of HPER.
A study by Indiana University researchers found that athletes' elevated or heavier breathing at sea level immediately following high-altitude training accounts for a substantial amount of the gains from the high-altitude training. The heavy breathing is temporary, however, said Robert Chapman, lecturer in IU's Department of Kinesiology, and makes a case for why athletes should consider giving themselves one week to 10 days at sea level before a major competition. Elite endurance athletes, such as runners, swimmers and triathletes, often train at high altitudes for a month or more because the body creates more red blood cells to adapt to the lower oxygen content of the air. An increase in red blood cells can help athletes by shuttling more oxygen to fuel muscles when they compete nearer to sea level. Chapman said their study, however, found that the elevated breathing athletes experience temporarily when returning to sea level can account for 10 percent to 20 percent of the body's increase in its ability to consume oxygen. If athletes factor this time in before their competition, the heavy breathing would go away and they still would likely have the extra red blood cells, unless they wait too long. "It's a matter of balance," said Chapman who also heads Team Indiana Elite, a group of professional distance runners based in Bloomington. The study "Maximal Oxygen Consumption Changes After Altitude Training: Role of Ventilatory Acclimatization," was presented during the Altitude and Hypoxia: Training and Performance Session on Friday, May 29. Co-authors of the study include lead author Daniel P. Wilhite, Abigail S. Laymon, James M. McKenzie and Elisabeth A. Lundgren, all from Indiana University.
Other studies from Chapman and his colleagues include the following:
- The researchers examined whether athletes become more economical because of high-altitude training -- consuming less oxygen at any given speed once they return to sea level. Chapman said the researchers did not see any improvements. Economy was the same or worse, he said, in part because of the elevated breathing the athletes experienced when they returned to sea level. The study, "Running Economy Changes After High Altitude Training: Role of Ventilatory Acclimatization," was presented during the Altitude and Hypoxia: Training and Performance Session on Friday, May 29. Coauthors of this study are Lundgren, Wilhite, Laymon, McKenzie and Chapman.
- Researchers found that the use of high-speed accelerometers, which can record every footstep an athlete makes down to the millisecond, can be an accurate coaching tool. Chapman said coaches have used video and force plates to measure and characterize certain components of running mechanics. The equipment cannot follow an athlete's every move. Accelerometers are lightweight and can be attached to a runner's shoe, capturing each foot fall -- even if the sprinter's foot spends only 8 milliseconds on the ground. Chapman said the data can be useful to coaches in a variety of ways, such as learning how athletes' gait change when they fatigue and even predicting distances athletes might be best suited to run. The study, "Measurement of Gait In Elite Distance Runners Using Fast Sampling Accelerometers," was presented in the Gait Analysis II Session in room 201 on Saturday, May 30. Co-authors of the study include McKenzie, Wilhite, Laymon and Lundgren. This study was supported by a grant from the High Performance Division of USA Track and Field.
Two Indiana University studies have explored the potential use of two simple tests for not only predicting whether someone has exercise-induced asthma (EIA) but also its severity, without subjecting the patient to an exercise challenge. One test involves measuring exhaled breath levels of nitric oxide. The other involved measuring the pH level of exhaled breath. Researchers found that both tests could be effective at predicting EIA and its severity. Both tests can be performed in a doctor's office while the patient is at rest. With EIA, vigorous exercise triggers an acute narrowing of the airway afterward, making breathing difficult. Around 80 percent of people with asthma have this condition, also called exercise-induced bronchoconstriction. EIA also is found in an estimated 10 percent or more of elite athletes and as much as 10 percent of the general population without asthma. Below are more details about the studies:
- Previous research has shown that pre-exercise fraction of exhaled nitric oxide (FENO) levels, which is a marker of airway inflammation, is elevated in people who have EIA. FENO levels also are associated with post-exercise closure of large airways. This study demonstrated the same positive relationship between FENO and closure of small airways after exercise. The study involved 12 people with EIA and six people without EIA. Their FENO levels were measured before the study participants underwent a eucapnic voluntary hyperventilation challenge for six minutes. "Our study found that exhaled nitric oxide may be a useful tool in predicting EIB and the magnitude of both large and small airway changes as a result of exercise," said lead author Louise Turner, a doctoral student in the Department of Kinesiology. "It involves the use of a simple piece of equipment and does not require exercise." Co-authors of the study include Sandra Tecklenburg-Lund, Joel M. Stager and Mickleborough, all of IU's Department of Kinesiology in the School of Health, Physical Education and Recreation. The study, "Exhaled Nitric Oxide Is Correlated With Changes in Small And Large Airway Obstruction," was presented during the Respiratory Session on Friday, May 29.
- The second study found that study participants with EIA had significantly lower levels of exhaled pH, which might "indicate acidification of the airways in individuals with airway hyperresponsiveness," according to the study. The pH level also was related to the degree of closure of the small airways. This study involved 23 participants who had asthma and EIA and eight people who did not. The study participants were asked to breathe normally for 10 minutes while their exhaled breath was collected. They then underwent a eucapnic voluntary hyperventilation challenge for six minutes. Their pulmonary function was measured several times before and after the hyperventilation. Coauthors include lead author Tecklenburg-Lund, Turner, Stager and Mickleborough. The study, "Exhaled Breath Condensate pH is Correlated With Post-exercise Small Airway Obstruction," was presented during the Respiratory Session on Friday, May 29.
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