A Ab bs st tr ra ac ct t The purpose of the present study was to ascertain the influence of reduced breathing on the blood acid-base status during swimming at 90% velocity of maximal 200-m front crawl. Ten swimmers (age 16.6 ± 1.8 years, height 180 ± 7 cm and weight 70 ± 7 kg) volunteered to participate in this study. They performed maximal 200-m front crawl swim. Then they performed a sub-maximal front crawl swim twice to exhaustion: first, by taking breath every two strokes (B2) and second, by taking breath every four strokes (B4). The swimming velocity was deter- mined as 90% of maximal velocity at 200-m front crawl swim. Measures included lactate concentra- tion ([LA]) and parameters of blood acid-base sta- tus (pH, Po 2 , Pco 2 , [HCO 3 -]) before and during the first and the third minute after the exercise. Swimmers swam with B2 significantly longer as they did with B4 (p < 0.05). [LA] was significantly lower after swimming with B4 than after swimming with B2 (p < 0.05). Pco 2 and [HCO 3 -] were signifi- cantly higher after swimming with B4 than after swimming with B2 (p < 0.05). Po 2 and pH did not change significantly in response to reduced breath- ing during swimming. It may be concluded that the combination of severe hypercapnia, respiratory ac idosis and metabolic acidosis was the possible rea- son why swimmers had to stop earlier due to fatigue, when taking breath every four strokes. Key words: swimming, reduced breathing, blood acid base status, blood lactate F Fa ac cu ul lt ty y o of f S Sp po or rt t, , U Un ni iv ve er rs si it ty y o of f L Lj ju ub bl lj ja an na a, , S Sl lo ov ve en ni ia a *Corresponding author: Faculty of Sport, University of Ljubljana, Gortanova 22 SI-1000 Ljubljana, Slovenia T el.: +386 (0)1 5207796, fax: +386 (0)1 5207750 E-mail: nejc.kapus@sp.uni-lj.si I Iz zv vl le eč če ek k Namen raziskave je bil ugotoviti učinke zmanjšane- ga dihanja na kazalce acido baznega statusa krvi med plavanjem z 90 % hitrostjo pri 200 m kravl mak- simalno. V raziskavo je bilo vključenih 10 zdravih rekreativnih plavalcev (starost 16,6 ± 1,8 let, višina 180 ± 7 cm in teža 70 kg ± 7 kg), ki so najprej kar najhitreje odplavali 200 m kravl. Nato so odplavali še dve submaksimalni plavanji kravla, prvič z vdi- hom na vsak drugi zaveslaj (B2) in drugič z vdihom na vsak četrti zaveslaj (B4). Plavali so tako dolgo, dokler so lahko ohranjali 90 % hitrosti od 200 m kravl maksimalno. Pri tem smo merili: vsebnost laktata ([LA]) in kazalce acido baznega statusa v krvi (pH, Po 2 , Pco 2 in [HCO 3 -]). Vzorce smo jemali pred naporom in v prvi ter tretji minuti po naporu. Plavalci so plavali z B2 statistično značilno dlje kakor z B4 (p < 0,05). Pri tem je bila vsebnost laktata statistično značilno nižja, vrednosti Pco 2 in [HCO 3 -] pa statis- tično značilno višji po plavanju z B4 v primerjavi s plavanjem z B2 (p < 0.05). Na osnovi teh rezultatov smo zaključili, da je kombinacija hiperkapnije in res- piratorne ter metabolične acidoze možen razlog za krajše plavanje ob vdihih na vsak četrti zaveslaj. Ključne besede: plavanje, zmanjšano dihanje, acido bazni status krvi, krvni laktat Faculty of Sport, University of Ljubljana, ISSN 1318-2269 Kinesiologia Slovenica, 9, 1, 12-17 (2003) 1 12 2 I IN NF FL LU UE EN NC CE E O OF F R RE ED DU UC CE ED D B BR RE EA AT TH HI IN NG G D DU UR RI IN NG G I IN NT TE EN NS SE E F FR RO ON NT T C CR RA AW WL L S SW WI IM MM MI IN NG G O ON N S SO OM ME E R RE ES S- - P PI IR RA AT TO OR RY Y A AN ND D M ME ET TA AB BO OL LI IC C V VA AL LU UE ES S I IN N B BL LO OO OD D V VP PL LI IV VI I Z ZM MA AN NJ JŠ ŠA AN NE EG GA A D DI IH HA AN NJ JA A M ME ED D I IN NT TE EN NZ ZI IV VN NI IM M P PL LA AV VA AN NJ JE EM M K KR RA AV VL LA A N NA A N NE EK KA AT TE ER RE E D DI IH HA AL LN NE E I IN N M ME ET TA AB BO OL LN NE E K KA AZ ZA AL LC CE E V V K KR RV VI I J Je er rn ne ej j K Ka ap pu us s* * A An nt to on n U Uš ša aj j V Ve en nc ce es sl la av v K Ka ap pu us s B Bo or ro o Š Št tr ru um mb be el lj j I IN NT TR RO OD DU UC CT TI IO ON N The pulmonary ventilation during swimming is synchronised with swimming strokes. Therefore the breathing frequency is in accordance with the stroke frequency. It may be assumed that the swimming velocity and stroke frequency should also be regulated, so that the needs of increased pulmonary ventilation are met. If the breathing pattern is changed at a similar veloc- ity, this may influence blood oxygenation and acid-base status as well as the swimmer’s per- formance. It has been believed that reduced breathing (taking breath every four, six or eight strokes) during front crawl swimming induced arterial hypoxemia, and enhanced lactate pro- duction in working muscles (Counsilman, 1977). Therefore this training technique is often referred to as “hypoxic training” (Maglischo, 1990). In some previous studies swimmers reduced the breathing frequency (taking breath every four, six and eight strokes) during teth- ered flume front crawl swimming (Dicker, Lofthus, Thornton, & Brooks, 1980; T own, & Vanness, 1990), in interval training (Holmer, & Gullstrand, 1980) and during front crawl swimming at OBLA velocity (Kapus, Ušaj, Kapus, & Štrumbelj, 2002). These studies were unable to demon- strate reduced arterial oxygen saturation with this training technique, but did show a systemat- ic hypercapnia. Kapus, Ušaj, Kapus and Štrumbelj (2002) also presumed that influences of reduced breathing during front crawl swimming would be more evident at higher velocity. The question is whether reduced breathing during swimming (taking breath every four strokes, which is often used during front crawl swimming), which induces respiratory acidosis, is suffi- cient to produce greater impacts on acid-base status and a swimmer’s performance, given the impacts of the already present metabolic acidosis of heavy exercise. Matheson and McKenzie (1988) demonstrated that breath holding during intermittent intense exercise induced rapidly reversible respiratory acidosis superimposed on the metabolic acidosis of maximal exercise. Unfortunately, these data were not obtained during swimming. They also used 15-second breath holds, which is much longer that 3.3 seconds of expiratory time measured during front crawl swimming when taking breath every four strokes (Kapus, & Ušaj, 2002). Therefore the purpose of the present study was to ascertain the influence of reduced breathing on the blood acid-base status during swimming at 90% velocity of maximal 200-m front crawl. M ME ET TH HO OD D P Pa ar rt ti ic ci ip pa an nt ts s Ten recreational swimmers (age: M = 16.6 years, SD = 1.8 years; height: M = 180 cm, SD = 7 cm; weight: M = 70 kg, SD = 7 kg) volunteered to participate in this study. I In ns st tr ru um me en nt ts s B Bl lo oo od d c co ol ll le ec ct ti io on n a an nd d b br re ea at th hi in ng g m me ea as su ur re em me en nt ts s Blood gas and acid-base parameters (pH, Po 2 , Pco 2 , [HCO 3 -]) and [LA] were measured before and after sub-maximal swimming with different breathing frequency. Capillary blood samples (60 – 80 ml) were collected in the first and the third minute after each swim from a hyperemied earlobe for pH, Po 2 , Pco 2 , [HCO 3 -] analysis using an ABL5 (Radiometer Copenhagen) instru- ment. [LA] was analysed with the use of MINI8 (LANGE, Germany) photometer. P Pr ro oc ce ed du ur re e First, swimmers performed maximal 200-m front crawl swim. Then they performed sub-maximal Reduced breathing during intense front crawl swimming Kinesiologia Slovenica, 9, 1, 12-17 (2003) 1 13 3 front crawl swimming twice: first, by taking breath every two strokes (B2), and second, by taking breath every four strokes (B4). They swam as long as possible at fixed, pre-determined velocity, which equalled 90% of velocity achieved during a 200-m front crawl. Stroke rate of sub-maximal swimming with B4 was the same as with B2, since we knew that swimmers reduced swimming velocity and/or increased stroke rate, when the need to breathe became critical during swim- ming with reduced breathing (T own, & Vanness, 1990). The values were presented as means ± standard deviations (SD). The paired t-test was used to compare the data obtained during submaximal front crawl swimming (the term swimming will be used in the sense of front crawl swimming in the following text) under two different sets of breathing conditions. R RE ES SU UL LT TS S Measurements of the swimming distance and breathing frequency during swimming under two different sets of breathing conditions are given in T able 1. T Ta ab bl le e 1 1: : C Co om mp pa ar ri is so on ns s o of f t th he e s sw wi im mm mi in ng g d di is st ta an nc ce e a an nd d b br re ea at th hi in ng g f fr re eq qu ue en nc cy y ( (f fb b) ) d du ur ri in ng g s sw wi im mm mi in ng g u un nd de er r t tw wo o d di if ff fe er r- - e en nt t s se et ts s o of f b br re ea at th hi in ng g c co on nd di it ti io on ns s ( (B B2 2 a an nd d B B4 4) ). . L Le eg ge en nd d: : M – mean values; SD – standard deviation; Paired t-test (** p < 0.01) Swimmers swam with B2 significantly longer as they did with B4 (p < 0.01). Comparisons of [LA] and pH values before and after swimming under two different sets of breathing condi- tions are given in Figure 1. Reduced breathing during intense front crawl swimming Kinesiologia Slovenica, 9, 1, 12-17 (2003) 1 14 4 F Fi ig gu ur re e 1 1: : C Co om mp pa ar ri is so on ns s o of f [ [L LA A] ] a an nd d p pH H v va al lu ue es s b be ef fo or re e a an nd d a af ft te er r s sw wi im mm mi in ng g u un nd de er r t tw wo o d di if ff fe er re en nt t s se et ts s o of f b br re ea at th hi in ng g c co on n- - d di it ti io on ns s ( (* * p p < < 0 0. .0 05 5, , * ** * p p < < 0 0. .0 01 1) ). . [LA] was significantly lower after swimming with B4 than after swimming with B2 (p < 0.01). As expected, pH values measured in the first minute after the exercise did not change under two different sets of breathing conditions. The swimmers were told to swim as long as they were able to. Therefore it seemed that 7 .22 is the limit pH value. But there were significant differences in pH measured in the third minute of recovery (p < 0.05). Pco2 and [HCO3-] values before and after swimming under two different sets of breathing conditions are stated in Figure 2. F Fi ig gu ur re e 2 2: : C Co om mp pa ar ri is so on ns s o of f P Pc co o2 2 a an nd d [ [H HC CO O3 3- -] ] v va al lu ue es s b be ef fo or re e a an nd d a af ft te er r s sw wi im mm mi in ng g u un nd de er r t tw wo o d di if ff fe er re en nt t s se et ts s o of f b br re ea at th h- - i in ng g c co on nd di it ti io on ns s ( (* ** * p p < < 0 0. .0 01 1) ). . Pco 2 and [HCO 3 -] were significantly higher after swimming with B4 than after swimming with B2 (p < 0.01). F Fi ig gu ur re e 3 3: : C Co om mp pa ar ri is so on ns s o of f P Po o 2 2 v va al lu ue es s b be ef fo or re e a an nd d a af ft te er r s sw wi im mm mi in ng g u un nd de er r t tw wo o d di if ff fe er re en nt t s se et ts s o of f b br re ea at th hi in ng g c co on nd di it ti io on ns s. . Figure 3 shows that Po 2 did not change significantly in response to reduced breathing during swimming. Reduced breathing during intense front crawl swimming Kinesiologia Slovenica, 9, 1, 12-17 (2003) 1 15 5 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Before the exercise During 1. min. after the exercise During 3. min. after the exercise LA (mmol/l) Swimming with B2 Swimming with B4 7,10 7,15 7,20 7,25 7,30 7,35 7,40 7,45 Before the exercise During 1. min. after the exercise During 3. min. after the exercise pH Swimming with B2 Swimming with B4 3,5 4,0 4,5 5,0 5,5 6,0 6,5 Before the exercise During 1. min. after the exercise During 3. min. after the exercise Pco 2 (kPa) Swimming with B2 Swimming with B4 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Before the exercise During 1. min. after the exercise During 3. min. after the exercise HCO 3 - (mmol/l) Swimming with B2 Swimming with B4 9,0 9,5 10,0 10,5 11,0 11,5 12,0 12,5 13,0 13,5 14,0 Before the ex ercise Du ring 1. min. after the ex ercise Du ring 3. min. after the ex ercise Po 2 (kPa) Swimming with B2 Swimming with B4 D DI IS SC CU US SS SI IO ON N In the present study both experimental conditions (normal and reduced breathing) applied the same relative work load. The swimmers were told to swim as long as they were able to maintain steady velocity. According to this instruction the swimming intensities were maximal for select- ed velocity and different durations for specific breathing conditions. This was different from the previous studies (Holmer, & Gullstrand, 1980; Dicker, Lofthus, Thornton, & Brooks, 1980; T own, & Vanness, 1990; Kapus, Ušaj, Kapus, & Štrumbelj, 2002), which concentrated on reduced breathing during exercise. In these studies the experimental exercises were restricted by time and/or by distance. According to this, it was expected that pH would be almost the same after both swims with different breathing frequency (Figure 1). But higher Pco 2 and [HCO 3 -] (Figure 2) and lower [LA] (Figure 1) after swimming with B4 indicated that reduced breathing during intense swimming induced respiratory acidosis in capillary blood, which also persisted during recovery. Stanford, Williams, Sharp and Bevan (1985) concluded that reduced breathing dur- ing the exercise resulted primarily in an inhibition of the normal respiratory compensation that occurred during the exercise with normal breathing. In the present study swimmers swam with B2 for about 132 meters more than with B4. It may be concluded that respiratory acidosis superimposed on the metabolic acidosis of maximal swimming was the reason why swim- mers were not able to swim longer while taking breath every four strokes. In the present study the average Pco 2 ( M = 5.5 kPa, SD = 0.8 kPa; Figure 2) measured in the first minute after swimming under B4 conditions was within the upper limit of Pco 2 with a resting healthy subject. Dicker, Lofthus, Thornton, & Brooks (1980) and T own & Vanness (1990) meas- ured Paco 2 to be about 5.9 kPa (SD = 0. 13 kPa) during swimming with B4. Considering the fast exchange of CO 2 between blood and alveolar air, it may be concluded that the actual Pco 2 at the end of swimming is higher than Pco 2 measured after 1-minute rest. Higher Pco 2 may have constituted a major stress during swimming with reduced breathing (Dicker, Lofthus, Thornton, & Brooks, 1980). In the third minute after swimming with B4, pH was significantly higher than the pH measured in the third minute after swimming with B2 (Figure 1). Kapus and Ušaj (2002) measured V E during recovery after swimming with and without reduced breathing. Their measurements showed that V E measured immediately after swimming was about 5% higher after swimming with B4 than after swimming with normal breathing. It seemed that ele- vated Pco 2 after swimming with reduced breathing presented the main stimulus for faster res- piratory compensation of the acidosis during recovery. Yamamoto, Takei, Mutoh and Miyashita (1988), measuring the exercise on a bicycle ergometer, failed to support the previous idea of enhanced lactic acidosis as a product of reduced breathing during exercise. Holmer & Gullstrand (1980) and Matheson & McKenzie (1988) measured [LA] in rest intervals during intermittent exercise with reduced breathing. They obtained significantly lower or unchanged lactate levels during reduced breathing conditions. After the exercise with reduced breathing unchanged (T own, & Vanness, 1990; Stanford, Williams, Sharp, & Bevan, 1985; Kapus, Ušaj, Kapus, & Štrumbelj, 2002) or significantly higher (Matheson, & McKenzie, 1988; Y amamoto, T akei, Mutoh, & Miyashita, 1988) lactate levels were reported in comparison with nor- mal breathing exercise. Y amamoto, T akei, Mutoh and Miyashita (1988) concluded that inhibition of lactate efflux from working muscles due to hypercapnia occurred during the exercise with reduced breathing. In the present study the [LA] in the first and the third minute after swimming with B4 decreased by 19% and 23%, respectively, in comparison to swimming with B2 (Figure 1). It may be presumed that [LA] was lower during swimming with B4 first because of shorter swimming exer- cise. However, it maintained in working muscles as an effect of hypercapnia may also be possible. Reduced breathing during intense front crawl swimming Kinesiologia Slovenica, 9, 1, 12-17 (2003) 1 16 6 In the present study there was no statistical difference in Po 2 after swimming between B2 and B4 (Figure 3). T o our knowledge, hypoxia has not yet been proved a result of reduced breathing during swimming (Holmer, & Gullstrand, 1980; Dicker, Lofthus, Thornton, & Brooks, 1980; T own, & Vanness, 1990; Kapus, Ušaj, Kapus, & Štrumbelj, 2002). According to Dicker, Lofthus, Thornton and Brooks (1980) PAo 2 with B2 decreased by 14% in comparison with B4. But esti- mated arterial oxygen saturation was essentially undiminished during swimming with reduced breathing. The reason for this phenomenon could be increased V T during swimming with reduced breathing. Therefore it could be assumed that swimmers hold their breath closer to total lung capacity than to functional residual capacity, since we know that alveolar hypoxia was accentuated more during breath holding at functional residual capacity than at total lung capacity (Y amamoto, Mutoh, Kobayashi, & Miyashita, 1987). It may be concluded that the combination of severe hypercapnia, respiratory acidosis and metabolic acidosis was the possible reason why swimmers had to stop earlier due to fatigue, when taking breath every four strokes. R RE EF FE ER RE EN NC CE ES S Counsilman J. E. (1977). Competitive swimming. Indiana: Counsilman Co Inc. Dicker, S. G., Lofthus, G. K., Thornton, N. W., & Brooks, G. A. (1980). Respiratory and heart rate responses to con- trolled frequency breathing swimming. Medicine and science in sport and exercise, 1, 20 - 23. Kapus, J., & Ušaj, A. (2002). Pulmonary ventilation during swimming using backward extrapolation of its recovery curve. [Abstract]. 7th Annual Congress of the European College of Sport Science, Proceedings (pp. 195). Athens: Department of Sport Medicine and Biology of Physical Activity, Faculty of Physical Education and Sport Science, University of Athens. Kapus, J., Ušaj, A., Kapus, V., & Štrumbelj, B. (2002). The influence of reduced breathing during swimming on some respiratory and metabolic values in blood. Kinesiologia Slovenica, 8 (1), 14 – 18. Holmer, I., & Gullstrand, L. (1980). Physiological responses to swimming with a controlled frequency of breathing. Scandinavian journal of sports science, 2, 1 – 6. Maglischo, E. W. (1990). Swimming faster. Palo Alto: Mayfield Publishing Company. Matheson, G. O., & McKenzie, D. C. (1988). Breath holding during intense exercise: arterial blood gases, pH, and lac- tate. The journal of sports medicine and physical fitness, 64, 1947 – 1952. Stanford, P . D., Williams, D. J., Sharp, R. L., & Bevan, L. (1985). Effect of reduced breathing frequency during exercise on blood gases and acid-base balance. [Abstract]. Medicine and science in sport and exercise, 17 (2), 228. Town, G. P., & Vanness, J. M. (1990). Metabolic responses to controlled frequency breathing in competitive swim- mers. Medicine and science in sport and exercise, 22, 1 12 - 1 16. Yamamoto, Y., Mutoh, Y., Kobayashi, H., & Miyashita, M. (1987). Effects of reduced frequency breathing on arterial hipoxemia during exercise. European journal of applied physiology, 56, 522 – 527 . Yamamoto, Y., Takei, Y., Mutoh, Y., & Miyashita, M. (1988). Delayed appearance of blood lactate with reduced fre- quency breathing during exercise. European journal of applied physiology, 57, 462 – 466. Received: 17 March 2003 -Accepted: 3 June 2003 Reduced breathing during intense front crawl swimming Kinesiologia Slovenica, 9, 1, 12-17 (2003) 1 17 7