The purpose of this study was to clarify the b reathing characteristics of backstroke swimming and to establish some teaching methods of the backstroke. An experiment was conducted to examine the relationship between breathing pattern and stroke motion by investigating nasal pressure while swimming and videotaping the stroke motion in the water. Thus, nasal pressure was measured while swimming the backstroke using an air-pressure transducer and the stroke motion was filmed using a digital video camera, investigating the breathing pattern, stroke mechanics, and their relationship. The results are as follows:
1) Two types of breathing in the backstroke were observed: 1 stroke cycle 1 breath (Type A) and 1 stroke cycle 2 breathes (Type B) Irregular breathing type was observed in the inexperien c ed (Type C). The incidence of Type B was 37.5% for trained swimmers and 4 0.0% for the experienced. There were diverse breathing patterns in the inexperienced.
2) The exhalation rate of the experienced was significantly smaller than that of the trained in fast-paced swimming and in slow-paced swimming (p<0.05). There was no significan t difference with the inexperienced. The exhalation rate of the trained in slow-paced s wimming was significantly longer than that in fast-paced swimming (p<0.05).
3) The time for the maximum exhalation in terms of nasal pressure was the moment that one hand entered the water for Type A and the moment that one hand began to stroke for Type B. The nasal pressure appeared greater in the fast-paced swimming of the trained (3.0+1.2 cmH 2 0)compared to the slow-paced swimming of the trained (2.3+0.8 c H20) and the untrain e d (2.2±1.1 c mH20). There was a significant difference between fast-paced swimming and slow-p a ced swimming of the trained (p<0.05).
4) The nasal pressure of the trained was greater in fast-paced swimming (3.2±1.4cmH20,2.5±0.7cmH20) than in slow-paced swimming (2.5±0.9 cmH20,1.9±0.4 cmH20) for both Type A and Type B; a significant difference (p<0.05) was observed between the two kinds of pace in all breathing types. The nasal pressure of the experienced appeared slightly greater in Type A (2.7±1.0 cmH20) than in Type B (1.4±0.2 cmH20) and Type C (1.3±0.7 cmH20). There was v ery little difference between Type B and Type C.
The above findings showed that when teach ing the backstroke one needs to fully understand what type of breathing, Type A or Type B, the swimmer excels at and to teach in line with the characteristics of individual breathing patterns.