Indiana U. Research At The American College Of Sports Medicine Conference

Main Category: Sports Medicine / Fitness
Also Included In: Respiratory / Asthma;  Nutrition / Diet
Article Date: 01 Jun 2009 - 0:00 PDT

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CAFFEINE SHOWN AS EFFECTIVE AT REDUCING EXERCISE-INDUCED ASTHMA SYMPTOMS AS AN ALBUTEROL INHALER

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 at the American College of Sports Medicine conference during the Respiratory Session on Friday morning. 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.

STUDY SHEDS LIGHT ON HOW TO MAXIMIZE BENEFITS OF HIGH ALTITUDE TRAINING

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 at the AMSC conference during the Altitude and Hypoxia: Training and Performance Session Friday morning. 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 morning. 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," will be presented in the Gait Analysis II Session in room 201 on Saturday from 10:30 a.m. to 10:45 a.m. PDT. 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 STUDIES EXPLORE WAYS TO PREDICT EXERCISE-INDUCED ASTHMA AND ITS SEVERITY WITHOUT REQUIRING AN EXERCISE CHALLENGE

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 Friday morning.
  
  
• 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 morning.

Source:
Tracy James
Indiana University