This article was downloaded by: [University of Notre Dame Australia] On: 05 May 2013, At: 10:17 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Sports Sciences Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/rjsp20
Repeated bouts of sprint running after induced alkalosis a
a
a
G.C. Gaitanos , M.E. Nevill , S. Brooks & C. Williams
a
a
Department of Physical Education and Sports Science, Loughborough University of Technology, Loughborough, LE11 3TU, UK Published online: 14 Nov 2007.
To cite this article: G.C. Gaitanos , M.E. Nevill , S. Brooks & C. Williams (1991): Repeated bouts of sprint running after induced alkalosis, Journal of Sports Sciences, 9:4, 355-370 To link to this article: http://dx.doi.org/10.1080/02640419108729896
PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-andconditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Journal of Sports Sciences, 1991, 9, 355-370
Repeated bouts of sprint running after induced alkalosis G.C. GAITANOS, M.E. NEVILL,* S. BROOKS and C. WILLIAMS
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
Department of Physical Education and Sports Science, Loughborough University of Technology, Loughborough LE11 3TU, UK
Accepted 19 November 1990
Abstract Seven healthy male subjects performed 10 maximal 6-s sprints, separated by 30-s recovery periods, on a non-motorized treadmill. On two occasions, separated by 3 days, the subjects ingested a solution of either sodium bicarbonate (NaHCO3; alkaline) or sodium chloride (NaCl; placebo), 2.5 h prior to exercise. The doses were 0.3 g kg-1 body mass for the alkaline treatment and 1.5 g total for the placebo, dissolved in 500 ml of water. The order of testing was randomly assigned. Pre-exercise blood pH was 7.43 ± 0.02 and 7.38 ± 0.01 for the alkaline and placebo trials respectively (P < 0.01). Performance indices (i.e. mean and peak power outputs and mean and peak running speeds) were significantly reduced as a result of the cumulative effects of successive sprints, but not significantly affected by the treatments. However, the total work done (i.e. mean power output) in the alkaline condition was 2% higher than that achieved in the placebo condition. Post-exercise blood lactate concentrations were higher for the alkaline treatment than for the placebo condition (15.3 ± 3.7 vs 13.6 ± 3.0 mM respectively; P < 0.01), but blood pH was similar in both conditions (alkaline: 7.15 ± 0.13; placebo: 7.09 ± 0.11). In both conditions, a relationship was found between post-exercise blood lactate and mean power output (alkaline: r = 0.82, P < 0.01; placebo: r = 0.79, P < 0.01). No significant differences were found in VE, VO2 and VCO2 between the two experimental conditions. This study demonstrates that alkali ingestion results in significant shifts in the acid-base balance of the blood, but has no effect on the power output during repeated bouts of brief maximal exercise. Keywords: Bicarbonate, pH, lactate, respiratory changes, intermittent exercise, sprinting.
Introduction The onset of fatigue during short-term all-out exercise has been attributed, in part, to acidosis as a result of H + accumulation in the muscle cell. Therefore, an increase in muscle buffering capacity or in the rate of H + efflux from muscle to the circulation should delay the onset of fatigue. A number of studies have attempted to increase buffering capacity by giving buffering *To whom all correspondence should be addressed. 0264-0414/91 $03.00 + .12 © 1991 E. & F.N. Spon
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
356
Gaitanos et al.
substances prior to exercise. However, the results of these studies are both conflicting and inconclusive. Nevertheless, there have been reports of longer exercise times to exhaustion lasting more than 5 min after inducing alkalosis using sodium bicarbonate (NaHCO 3 ) (Jones et al., 1977; Sutton et ah, 1981). The ergogenic effect of NaHCO 3 has also been demonstrated in field studies. Wilkes and co-workers (1983) reported that trained track athletes had significantly faster times in an 800-m race when they ingested NaHCO 3 prior to competition. The average improvement was 2.9 s and represents a distance of 19 m. It has also been reported that the average 400-m running time was improved by 1.52 s after ingestion of NaHCO 3 , which caused blood pH and standard bicarbonate concentration to be higher than in the placebo condition (Goldfinch et al., 1988). In contrast, no improvement in performance time was observed in a 400-m run when alkalosis was induced by the infusion of bicarbonate or Tris-buffer, despite elevation of the buffering capacity of the blood to over 5 mM and blood pH to 7.5 (Kindermann et al., 1977). The claim that the induction of preexercise alkalosis has no significant improvement on performance has also been supported by McCartney and co-workers (1983), who also demonstrated that the total work done over a 30-s isokinetic cycle ergometer test (100 rev min" 1 ) after ingestion of NaHCO 3 was only 101 % ofthat achieved with a placebo. Similarly, alkalosis had no significant effect on a single bout of cycling exercise to exhaustion at an intensity corresponding to 125% VO2 max (Katz et al, 1984). The influence of 'bicarbonate loading' on performance during intermittent exercise has received relatively little attention in contrast with the studies on continuous high-intensity exercise. It has been shown that endurance time was improved by 42% in the fifth bout of exercise preceded by four 1-min bouts of exercise at 125% VO2 max (Costill et al., 1984). In the same study, ingestion of bicarbonate resulted in a post-exercise muscle pH of 6.81, compared to 6.73 in the control condition. Employing an identical exercise protocol, Winjen and co-workers (1984) observed only a modest and non-significant improvement in endurance time. Additionally, Parry-Billings and MacLaren (1986) failed to observe any significant differences in the maximal power output and the total work done over three 30-s bouts of maximal cycling exercise, despite the significant shifts in acid-base balance of the blood that occurred as a result of NaHCO 3 or sodium citrate ingestion. Recently, it has also been shown that power output during exercise consisting of ten 10-s sprints on the cycle ergometer, with a recovery period of 50 s between each sprint, was enhanced following induced alkalosis (Lavender and Bird, 1989). In the present study, an intermittent high-intensity exercise test was used, in order to examine the influence of NaHCO 3 administration on exercise performance. The exercise protocol consisted of ten 6-s sprints with 30 s rest between each sprint on a non-motorized treadmill. During this type of exercise, fatigue is seen as a gradual process resulting in decrements in power output (Cheetham et al., 1986).
Methods Subjects Seven healthy male physical education students whose mean age, height and body mass were 24.0+1.9 years, 176.8 + 9.2 cm and 71.9 + 9.7 kg respectively, gave their informed consent and volunteered to take part in this study.
Intermittent exercise after induced alkalosis
357
Protocol
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
The subjects completed two identical tests separated by 3 days. On each occasion, following a fast of at least 4 h, the subjects ingested a solution of either sodium bicarbonate (NaHCO 3 ) or sodium chloride (NaCl). The doses were 0.3 g kg"* body mass for the alkaline treatment and 1.5 g for the placebo. Both the NaHCO 3 and the NaCl were dissolved in 500 ml of water and consumed within 10 min. The taste of both solutions was very similar, and therefore the subjects were not able to distinguish between the two solutions. The order of testing was randomly assigned and the exercise was performed 2.5 h after the ingestion of the NaHCO 3 or NaCl solution. An initial pilot study had shown that blood bicarbonate concentration, base excess and blood pH were significantly elevated after this treatment (Table 1). Multiple sprint test The exercise test consisted of 10 maximal 6-s sprints on a non-motorized treadmill with 30 s rest between each sprint. The design of this equipment has previously been described (Lakomy, 1987). The treadmill allowed the subjects to sprint at their maximum speeds and also to change speed as fatigue occurred. Additionally, it was possible to monitor the power output during each sprint while the subjects were running at maximal speed and follow the decline in power output throughout the exercise period. The methodology for determining these performance variables and the terminology used are described in more detail in Hamilton et al. in this issue. All of the subjects had previously been familiarized with treadmill sprinting until they were fully confident of producing an „all-out effort. Approximately 2.2 h after salt ingestion, the subjects were allowed a 5-min period of gentle jogging and stretching exercises. This was followed by a standardized warm-up procedure that involved two 30-s periods of submaximal running at 2.78 and 3.33 m s" 1 (10 and ^ k m h " 1 ) respectively, separated by 30s of recovery. These runs also served to re-accustom the subjects to the experimental procedures. Five minutes after this standardized warm-up, the subjects performed the exercise test. Six seconds prior to each sprint, the subjects were instructed to attain an initial running speed of 2.22 m s " 1 (8 km h" 1 ) as quickly as possible and were counted down into the next sprint, whereas during the preceding 24 s of the recovery period they simply stood quietly on the treadmill so that the recovery period was standardized. The subjects were instructed to run maximally from the start of the test and were verbally encouraged throughout. The same amount of external motivation was given in both experimental conditions.
Blood sampling and analysis Venous blood samples were obtained 2 h after ingestion and at 1 min following conclusion of the last sprint for the determination of blood pH, haemoglobin concentration and haematocrit. Additionally, arterialized capillary samples were taken 4 min after the standardized warm-up and at 3,5 and 30 min following completion of the final sprint for the determination of blood lactate and blood glucose concentrations. Venous blood samples were placed into lithium-heparin tubes to prevent coagulation and blood pH was determined immediately (Corning pH blood/gas meter, model 161). Changes in plasma volume were estimated from the pre- and post-sprint haematocrit and haemoglobin values (Dill and Costill, 1974). Capillary blood was obtained from the thumb of each subject after warming
358
Gaitanos et al.
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
the hand in order to obtain arterialized samples. Duplicate 25-/zl samples were collected in disposable glass capillary tubes. The samples were immediately de-proteinized in 250 jil 2.5% perchloric acid and the precipitate was separated by centrifugation (Eppendorf model 5412). The samples were then frozen at —20° C and analysed fluorimetrically at a later date for blood lactate concentration (Perkin-Elmer, model 1000) and photometrically for blood glucose (Maughan, 1982). Urine samples were collected prior to ingestion of the salt solution, prior to warm-up and approximately 45 min following completion of the final sprint. The samples from each subject were kept at 4° C and analysed for pH (Corning pH blood/gas meter) within 1 h of completing the test. Physiological responses
Heart rate was monitored continuously during the exercise test and for the first 15 min of recovery while the subjects were sitting on an examination couch. Samples of expired air were collected during rest, during each sprint and recovery interval, and during the first 15 min of passive recovery while the subjects were sitting on an examination couch. Expired air samples were collected in Douglas bags and analysed for percentages of oxygen and carbon dioxide using a mass spectrometer (Centronics Ltd, model C) and for volume using a calibrated dry gas meter (Harvard Instruments). Statistical analyses Differences in performance characteristics and respiratory responses to multiple sprinting were examined employing a two-way ANOVA with repeated measures on two factors (experimental condition and sprint number). The combined effect of the two independent variables was also determined. The same test was used to examine differences in blood lactate and blood glucose concentrations between the two conditions. Where significant F-ratios were determined, the means were compared using the Tukey test. Differences in blood and urine pH values between the two conditions were examined using the Student's (-test for correlated means. Statistical analysis was accepted at the 5% level and was established prior to the investigation.
Results Performance variables
The mean power output (MPO) values recorded during each sprint and the peak power output (PPO) values are shown in Fig. 1. A significant difference (P
Journal of Sports Sciences Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/rjsp20
Repeated bouts of sprint running after induced alkalosis a
a
a
G.C. Gaitanos , M.E. Nevill , S. Brooks & C. Williams
a
a
Department of Physical Education and Sports Science, Loughborough University of Technology, Loughborough, LE11 3TU, UK Published online: 14 Nov 2007.
To cite this article: G.C. Gaitanos , M.E. Nevill , S. Brooks & C. Williams (1991): Repeated bouts of sprint running after induced alkalosis, Journal of Sports Sciences, 9:4, 355-370 To link to this article: http://dx.doi.org/10.1080/02640419108729896
PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-andconditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sublicensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Journal of Sports Sciences, 1991, 9, 355-370
Repeated bouts of sprint running after induced alkalosis G.C. GAITANOS, M.E. NEVILL,* S. BROOKS and C. WILLIAMS
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
Department of Physical Education and Sports Science, Loughborough University of Technology, Loughborough LE11 3TU, UK
Accepted 19 November 1990
Abstract Seven healthy male subjects performed 10 maximal 6-s sprints, separated by 30-s recovery periods, on a non-motorized treadmill. On two occasions, separated by 3 days, the subjects ingested a solution of either sodium bicarbonate (NaHCO3; alkaline) or sodium chloride (NaCl; placebo), 2.5 h prior to exercise. The doses were 0.3 g kg-1 body mass for the alkaline treatment and 1.5 g total for the placebo, dissolved in 500 ml of water. The order of testing was randomly assigned. Pre-exercise blood pH was 7.43 ± 0.02 and 7.38 ± 0.01 for the alkaline and placebo trials respectively (P < 0.01). Performance indices (i.e. mean and peak power outputs and mean and peak running speeds) were significantly reduced as a result of the cumulative effects of successive sprints, but not significantly affected by the treatments. However, the total work done (i.e. mean power output) in the alkaline condition was 2% higher than that achieved in the placebo condition. Post-exercise blood lactate concentrations were higher for the alkaline treatment than for the placebo condition (15.3 ± 3.7 vs 13.6 ± 3.0 mM respectively; P < 0.01), but blood pH was similar in both conditions (alkaline: 7.15 ± 0.13; placebo: 7.09 ± 0.11). In both conditions, a relationship was found between post-exercise blood lactate and mean power output (alkaline: r = 0.82, P < 0.01; placebo: r = 0.79, P < 0.01). No significant differences were found in VE, VO2 and VCO2 between the two experimental conditions. This study demonstrates that alkali ingestion results in significant shifts in the acid-base balance of the blood, but has no effect on the power output during repeated bouts of brief maximal exercise. Keywords: Bicarbonate, pH, lactate, respiratory changes, intermittent exercise, sprinting.
Introduction The onset of fatigue during short-term all-out exercise has been attributed, in part, to acidosis as a result of H + accumulation in the muscle cell. Therefore, an increase in muscle buffering capacity or in the rate of H + efflux from muscle to the circulation should delay the onset of fatigue. A number of studies have attempted to increase buffering capacity by giving buffering *To whom all correspondence should be addressed. 0264-0414/91 $03.00 + .12 © 1991 E. & F.N. Spon
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
356
Gaitanos et al.
substances prior to exercise. However, the results of these studies are both conflicting and inconclusive. Nevertheless, there have been reports of longer exercise times to exhaustion lasting more than 5 min after inducing alkalosis using sodium bicarbonate (NaHCO 3 ) (Jones et al., 1977; Sutton et ah, 1981). The ergogenic effect of NaHCO 3 has also been demonstrated in field studies. Wilkes and co-workers (1983) reported that trained track athletes had significantly faster times in an 800-m race when they ingested NaHCO 3 prior to competition. The average improvement was 2.9 s and represents a distance of 19 m. It has also been reported that the average 400-m running time was improved by 1.52 s after ingestion of NaHCO 3 , which caused blood pH and standard bicarbonate concentration to be higher than in the placebo condition (Goldfinch et al., 1988). In contrast, no improvement in performance time was observed in a 400-m run when alkalosis was induced by the infusion of bicarbonate or Tris-buffer, despite elevation of the buffering capacity of the blood to over 5 mM and blood pH to 7.5 (Kindermann et al., 1977). The claim that the induction of preexercise alkalosis has no significant improvement on performance has also been supported by McCartney and co-workers (1983), who also demonstrated that the total work done over a 30-s isokinetic cycle ergometer test (100 rev min" 1 ) after ingestion of NaHCO 3 was only 101 % ofthat achieved with a placebo. Similarly, alkalosis had no significant effect on a single bout of cycling exercise to exhaustion at an intensity corresponding to 125% VO2 max (Katz et al, 1984). The influence of 'bicarbonate loading' on performance during intermittent exercise has received relatively little attention in contrast with the studies on continuous high-intensity exercise. It has been shown that endurance time was improved by 42% in the fifth bout of exercise preceded by four 1-min bouts of exercise at 125% VO2 max (Costill et al., 1984). In the same study, ingestion of bicarbonate resulted in a post-exercise muscle pH of 6.81, compared to 6.73 in the control condition. Employing an identical exercise protocol, Winjen and co-workers (1984) observed only a modest and non-significant improvement in endurance time. Additionally, Parry-Billings and MacLaren (1986) failed to observe any significant differences in the maximal power output and the total work done over three 30-s bouts of maximal cycling exercise, despite the significant shifts in acid-base balance of the blood that occurred as a result of NaHCO 3 or sodium citrate ingestion. Recently, it has also been shown that power output during exercise consisting of ten 10-s sprints on the cycle ergometer, with a recovery period of 50 s between each sprint, was enhanced following induced alkalosis (Lavender and Bird, 1989). In the present study, an intermittent high-intensity exercise test was used, in order to examine the influence of NaHCO 3 administration on exercise performance. The exercise protocol consisted of ten 6-s sprints with 30 s rest between each sprint on a non-motorized treadmill. During this type of exercise, fatigue is seen as a gradual process resulting in decrements in power output (Cheetham et al., 1986).
Methods Subjects Seven healthy male physical education students whose mean age, height and body mass were 24.0+1.9 years, 176.8 + 9.2 cm and 71.9 + 9.7 kg respectively, gave their informed consent and volunteered to take part in this study.
Intermittent exercise after induced alkalosis
357
Protocol
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
The subjects completed two identical tests separated by 3 days. On each occasion, following a fast of at least 4 h, the subjects ingested a solution of either sodium bicarbonate (NaHCO 3 ) or sodium chloride (NaCl). The doses were 0.3 g kg"* body mass for the alkaline treatment and 1.5 g for the placebo. Both the NaHCO 3 and the NaCl were dissolved in 500 ml of water and consumed within 10 min. The taste of both solutions was very similar, and therefore the subjects were not able to distinguish between the two solutions. The order of testing was randomly assigned and the exercise was performed 2.5 h after the ingestion of the NaHCO 3 or NaCl solution. An initial pilot study had shown that blood bicarbonate concentration, base excess and blood pH were significantly elevated after this treatment (Table 1). Multiple sprint test The exercise test consisted of 10 maximal 6-s sprints on a non-motorized treadmill with 30 s rest between each sprint. The design of this equipment has previously been described (Lakomy, 1987). The treadmill allowed the subjects to sprint at their maximum speeds and also to change speed as fatigue occurred. Additionally, it was possible to monitor the power output during each sprint while the subjects were running at maximal speed and follow the decline in power output throughout the exercise period. The methodology for determining these performance variables and the terminology used are described in more detail in Hamilton et al. in this issue. All of the subjects had previously been familiarized with treadmill sprinting until they were fully confident of producing an „all-out effort. Approximately 2.2 h after salt ingestion, the subjects were allowed a 5-min period of gentle jogging and stretching exercises. This was followed by a standardized warm-up procedure that involved two 30-s periods of submaximal running at 2.78 and 3.33 m s" 1 (10 and ^ k m h " 1 ) respectively, separated by 30s of recovery. These runs also served to re-accustom the subjects to the experimental procedures. Five minutes after this standardized warm-up, the subjects performed the exercise test. Six seconds prior to each sprint, the subjects were instructed to attain an initial running speed of 2.22 m s " 1 (8 km h" 1 ) as quickly as possible and were counted down into the next sprint, whereas during the preceding 24 s of the recovery period they simply stood quietly on the treadmill so that the recovery period was standardized. The subjects were instructed to run maximally from the start of the test and were verbally encouraged throughout. The same amount of external motivation was given in both experimental conditions.
Blood sampling and analysis Venous blood samples were obtained 2 h after ingestion and at 1 min following conclusion of the last sprint for the determination of blood pH, haemoglobin concentration and haematocrit. Additionally, arterialized capillary samples were taken 4 min after the standardized warm-up and at 3,5 and 30 min following completion of the final sprint for the determination of blood lactate and blood glucose concentrations. Venous blood samples were placed into lithium-heparin tubes to prevent coagulation and blood pH was determined immediately (Corning pH blood/gas meter, model 161). Changes in plasma volume were estimated from the pre- and post-sprint haematocrit and haemoglobin values (Dill and Costill, 1974). Capillary blood was obtained from the thumb of each subject after warming
358
Gaitanos et al.
Downloaded by [University of Notre Dame Australia] at 10:17 05 May 2013
the hand in order to obtain arterialized samples. Duplicate 25-/zl samples were collected in disposable glass capillary tubes. The samples were immediately de-proteinized in 250 jil 2.5% perchloric acid and the precipitate was separated by centrifugation (Eppendorf model 5412). The samples were then frozen at —20° C and analysed fluorimetrically at a later date for blood lactate concentration (Perkin-Elmer, model 1000) and photometrically for blood glucose (Maughan, 1982). Urine samples were collected prior to ingestion of the salt solution, prior to warm-up and approximately 45 min following completion of the final sprint. The samples from each subject were kept at 4° C and analysed for pH (Corning pH blood/gas meter) within 1 h of completing the test. Physiological responses
Heart rate was monitored continuously during the exercise test and for the first 15 min of recovery while the subjects were sitting on an examination couch. Samples of expired air were collected during rest, during each sprint and recovery interval, and during the first 15 min of passive recovery while the subjects were sitting on an examination couch. Expired air samples were collected in Douglas bags and analysed for percentages of oxygen and carbon dioxide using a mass spectrometer (Centronics Ltd, model C) and for volume using a calibrated dry gas meter (Harvard Instruments). Statistical analyses Differences in performance characteristics and respiratory responses to multiple sprinting were examined employing a two-way ANOVA with repeated measures on two factors (experimental condition and sprint number). The combined effect of the two independent variables was also determined. The same test was used to examine differences in blood lactate and blood glucose concentrations between the two conditions. Where significant F-ratios were determined, the means were compared using the Tukey test. Differences in blood and urine pH values between the two conditions were examined using the Student's (-test for correlated means. Statistical analysis was accepted at the 5% level and was established prior to the investigation.
Results Performance variables
The mean power output (MPO) values recorded during each sprint and the peak power output (PPO) values are shown in Fig. 1. A significant difference (P
