The subjects of the study underwent three weeks of altitude training (Kunming, Yunnan, China: altitude of 1,892 meters, average temperature of 23℃~27℃, average barometric pressure of 600~605 Pa (mmHg)) for cardiopulmonary endurance enhancement. The purpose of this study was to determine the inspiratory muscle enhancement period of swimmers in the Korea national team, and to provide the scientific basis for the effects made to 100 and 200 meter competition records, interval records, breath counts and stroke counts following altitude training.
Measurement and analyses were carried in the following manner. Effects on inspiratory muscle were measured by determining the maximum inspiratory muscle capacity and inspiratory muscle endurance in the pre-test (week 1) and post-test (week 5, week 6, week 7) respectively; performance was gauged through competition and interval records and the changes in the correlation between the competition record, underwater time, and breath count in the pre-test (week 1) and post-test (week 5).
The subjects of the study constitute swimmers in the current national team, South Korea, running 100 meter and 200 meter competitions. A total of twelve swimmers participated in the experiment and were grouped into six under butterfly and freestyle and six under breaststroke and backstroke in consideration of the differing respiration methods.
The study made use of a resistance inspiratory muscle measuring and training device (Powerbreathe K5), recording the maximum inspiratory muscle capacity variable (5 times per week) and inspiratory muscle endurance variable (twice per week), while performance was recorded through the means of video photography and analysis. The data collected in this study was assisted by the statistical software program SPSS version 18.0 for Windows in the following data processing method. The paired t-test was used to measure the inspiratory muscle and performance in 100 and 200 meter competitions (interval record and competition record) after the altitude training as compared to that beforehand. Regression analysis was utilized to determine the influence that stroke count, breath count, and underwater time have on 100 and 200 meter competition records before and after training. The significance level of the statistics indicated in the study results have been set at ?=0.05.

The study results are as follows:

1) Changes in inspiratory muscle through altitude training

(1) The variable maximum inspiratory muscle capacity did not show a significant difference in Peak Inspiratory Flow (Litres) after the experiment in week 5, 6, and 7 compared to week 1, whereas a statistically significant difference in week 5, 6, and 7 (P<0.0001, P<0.0002, P<0027) emerged in Peak S-Index (cmH₂O).

(2) The variable inspiratory muscle endurance indicated a significant difference (P<0.0097, P<0.0031) in Avg. Inspiratory Power (Watt) and Total Energy (Joule) in week 5 after the experiment in comparison to the first week; there was no sign of a significant difference in week 6, only in Avg. Inspiratory Power (Watt) in week 7 (P<0.0287).

2) Changes in competition performance through altitude training

(1) Competition records showed a significant difference in the 100 meter records of the butterfly and freestyle events, which were divided in consideration of varying respiration methods (P<0.0353).

(2) Interval records, having impacted all four interval record results of the 100 meter butterfly and freestyle competitions (P<0.0280, P<0.0154, P<0.0391), (P<0.0353), affected the results of the first, second and third interval records in the 200 meter breaststroke and backstroke competitions, indicating a significant difference (P<0.0018, P<0.0300 ,P<0.0314).

(3) In terms of stroke count, breath count, and underwater time, it appears underwater time after altitude training compared to that beforehand influenced competition records with a significant difference (P<0.0331).

In account of the above, the three week altitude training for the Korea national team swimmers showed to have contributed positively to the enhancement of their inspiratory muscle capacity and performance, and shortened records were observed in the 100 meter butterfly and freestyle competitions after training. Moreover in terms of interval records, improvements were apparent in the butterfly and freestyle events for the 100 meter competitions and likewise in the breaststroke and backstroke events for the 200 meter competitions. Of the various athletic performance capability factors of swimming such as stroke count, breath count, and underwater time, changes brought about in the underwater time after the training appeared to have had advantageous effects on shortening records.
In order to maximize the effect of altitude training in elite sports it is recommended that the appropriate tapering be implemented taking to account the periods of altitude training and competition, followed by altitude training ahead of competition participation. Also as much as altitude training showed a significant difference in underwater time, interval records and competition record, it seems befitting that optimum condition is maintained in this regard.