The effect of nebulised salbutamol and isotonic saline on exercise induced bronchoconsonstriction in elite skaters following a 1500 meter race.

Rationale:

Elite skaters perform in cold air, an environment which has a low absolute humidity. In training and during competition, when the level of exertion is high, the skater repeatedly breathes cold and dry air, resulting in an inflammation of the lungs similar to that seen in asthma. This inflammation may cause bronchus obstruction after exercise. In order to combat the consequences of performing in dry or unconditioned air, this research makes use of a fully portable ultrasonic nebulizer (OMRON).



Objective:

To analyze the additional benefits of nebulization with a solution of NaCl or salbutamol after exercise by elite skaters in dry air in comparison to elite skaters not nebulising (controls). Study design: Double dummy, randomized, placebo-controlled design.



Study population:

Group of 41 elite skaters in the 18 to 35 year age group.



Intervention:

Nebulization with 1 mg Salbutamol by means of ultrasonic nebulization after speedskating a distance of 1500 metres. Placebo group nebulization with 0.9% sodium chloride (NaCl); the control group will only complete the 1500 metres.



Main study parameters/endpoints:

Reduced decrease in FEV1 after exercise by the verum group compared to placebo and control groups among elite skaters.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

The participants will undergo a lung function test once before and three times after speedskating a distance of 1500 metres. The test consists of FOT and spirometric measurements. Further electromyographic measurements(EMG) take place during and after exercise. These measurements give information on muscle activity of the respiratory muscle system. The 1500 metres speedskating lasts approximately 3 minutes. Nebulization of salbutamol or 0.9% NaCl presents a minimal risk and is standard practice in the study population. The potential obstruction of the airways which may develop after a distance of 1500 metres in dry air can be compared with previous experiences with similar exertion by elite skaters.

To analyze the additional benefits of nebulization with a solution of NaCl or salbutamol after exercise by elite skaters in dry air in comparison to elite skaters not nebulising (controls). Reduced decrease in FEV1 after exercise by the verum group compared to placebo and control groups among elite skaters.

FOT measurements will be performed with R.O.S., Oscilink®, Sensormedics® to measure general respiratory resistance and reactance. FOT measurements will consist of 3 repeated measurements with nose clipped and with hands supporting cheeks and base of the mouth (Oostveen, et al., 2003). FOT measurements will be performed before and at 10, 15 and 30 minutes after exercise. The average of resistance and reactance values will be used for statistical analysis. A Masterscope® Jaeger®, will be used to measure flow -volume loops in accordance with current ERS/ATS guidelines (American Thoracic society, 1999). Lung function will be calculated from the best curve. Zapletal reference values will be used to calculate the % of the predicted value of the FEV1 (Zapletal & Chalupova, 2003). Flow volumes will be measured in duplicate before and at 11, 16 and 31 minutes after exercise, the best values at each time point retained for analysis. Electrical muscle activity (EMG) of the diaphragm and intercostal muscles was derived transcutaneously from pairs of single electrodes (disposable Neotrode, ConMed Corporation, NY) (Maarsingh et al., 2002). To obtain the electrical activity of the diaphragm, two electrodes were placed bilaterally below the costal margin in the nipple line (frontal lead of diaphragm) and two bilaterally on the back at the same level (dorsal lead of diaphragm). The mean value of the processed data of the frontal and dorsal leads of the diaphragm represented the electrical activity of the whole diaphragm. To obtain the electrical activity of the intercostals muscles, two electrodes were placed each in the second intercostal space left and right, 2 cm parasternal. A common electrode was placed at the height of the sternum.

Nebulization with 1 mg Salbutamol by means of ultrasonic nebulization after speedskating a distance of 1500 metres. Placebo group nebulization with 0.9% sodium chloride (NaCl). The control group will only complete the 1500 metres.