Applied Physiology
Eur J Appl Physiol (1992) 65:246-250
Europe.n Joumal of
and Occupational Physiology © Springer-Verlag 1992
Relationship between plasma ammonia and blood lactate concentrations after maximal treadmill exercise in circumpubertal girls and boys K. Nazar I, B. Dobrzyfiski 2, and R. Lewicki 3 ] Department of Applied Physiology,Medical Research Centre, Polish Academyof Sciences, 17 Jazgarzewska Str., 00-730 Warsaw, Poland 2 Institute of Sport, Warsaw, Poland 3 Department of Sports Medicine, MilitarySchool of Medicine, L6d~, Poland Accepted April 27, 1992
Summary. The purpose of the study was to define a relationship between plasma ammonia [NH3]pl and blood lactate concentrations [la-]b after exercise in children and to find out whether the [NH3]pb determined during laboratory treadmill tests, may be useful as a predictor of the children's sprint running ability. A group of 20 girls and 14 boys trained in athletics or swimming and 8 untrained boys, aged 13.2 to 13.7 years, participated in the study. Their [NH3]pl and [la-]b were measured before and after incremental maximal treadmill exercise. In addition, the subjects' running performance was tested in 30-, 60- and 600- or 1000-m runs under field conditions. The [NH3]pl during the treadmill runs increased by 20.1 (SD 17.3), 24 (SD 16.7) and 10 (SD 4.3) ~mol. 1- ~ in the girls, the trained boys and the untrained boys, respectively. The postexercise [NH3]p~ correlated positively with [la-]b (r= 0.565 in the girls and 0.812 in the boys) and treadmill speed attained during the test (r = 0.489 in the girls and 0.490 in the boys). Significant correlations were also found between [NH3]N obtained during the treadmill test and the times of 30- and 60-m runs (r= -0.676 and -0.648, respectively) in the boys but not in the girls. A comparison of the present data with those reported previously in adults showed that increases in [NH3]N during maximal exercise in children would seem to be lower than in adult subjects both in absolute values and in relation to [la-]b. The present data would also suggest that [NH3]pl reflects involvement of anaerobic processes during maximal treadmill exercise in circumpubertal children but it has a small practical value for predictiton of their sprint running ability. Key words: Children - Exercise - Ammonia - Lactate Running performance
Correspondence to: K. Nazar
Introduction Maximal anaerobic power and capacity of children, even when normalized for body mass or active muscle mass, have been shown to increase with age and maturation (e.g. Blimke et al. 1988; Crielaard and Pirnay 1985; Inbar and Bar-Or 1986; Vandenwalle et al. 1989). The unique biochemical studies on muscle biopsies taken from exercising children have revealed that the rates of glycogen utilisation and lactate production during maximal exercise in prepubescent boys are lower than those in adolescents and young adults (Ericsson 1980; Ericsson et al. 1973; Ericsson and Saltin 1974). It has also been shown that the activity of muscle phosphofructokinase, considered as a rate-limiting enzyme in glycolysis, increases with age (Ericsson and Saltin 1974). Muscles of young children have, therefore, lower glycolytic potential than those of older age groups. This is in line with the results of several studies which have demonstrated relatively low blood lactate ([la-],; Astrand 1952; Mero 1988; Paterson et al. 1986) and hydrogen ion (Gaisl and Buchberger 1977; Kinderman et al. 1975) concentrations after all-out efforts in pre-adolescents. Studies with adult human subjects have demonstrated that during high-intensity exercise an increase in [la-]b is accompanied by an increase in the plasma ammonia concentration ([NH3]pl; Babij et al. 1983; Buono et al. 1984; Dudley et al. 1983; Eriksson et al. 1985; Hageloch et al. 1990; Schlicht et al. 1990; Schwarke et al. 1987; Wilkerson et al. 1977). The changes in this metabolite concentration and their relationship to [la-]b have not been studied thoroughly in children. Thus, the aim of the present investigation was to define a relationship between [la-]b and [NH3]pl measured simultaneously after maximal exercise in circumpubertal girls and boys. Since NH3 during intensive exercise is produced mainly in fast twitch fibres (Tullson and Terjung 1990; Weicker et al. 1990) an attempt was also made to find out whether the [NH3lpl attained during incremental maximal exercise tests correlates with subjects' running performance on a treadmill and in short distance runs under field conditions.
247
Methods
Subjects. A group of 20 girls and 22 boys, aged 13.2-13.7 years, participated in this study. Informed consent, parental permission and medical clearance were obtained for all subjects. The study group included: elite junior swimmers (5 girls and 3 boys) who had been training in swimming for 5-6 years (18 h per week), "athletes" (15 girls and 11 boys) all practising diverse forms of athletics such as running at various distances, and jumping, etc. without specialisation for 3 years (12 h per week) and 8 untrained boys who participated only in the school physical education programme (2 h per week). The subjects' physical characteristics are listed in Table 1. Only 3 girls (1 swimmer and 2 athletes) attained menarche prior to the test, 8 girls (3 swimmers and 5 athletes) were at Tanner stage II and the remaining ones at stage I. Among boys, 13 were at Tanner stage II (2 swimmers, 8 athletes and 5 untrained) whereas the remaining 9 boys were at stage I. Treadmill tests were performed always in the morning, 2-3 h after a light meal consisting mainly of carbohydrate, at ambient
temperatures of 21-24°C and relative humidities of 55°70-60°7o. The subjects ran on a treadmill (Jaeger, FRG) at 0% gradient. The starting speed of 7.2 k m . h -1 was increased by 1.8 k m . h -1 every 2 min until the subjects reported exhaustion. Before the run and 3 min after its cessation blood was taken from the antecubital vein for [NH3]pIdetermination. The [la-]b was estimated in the arterialized blood taken from a fingertip at the same times. Both metabolites were measured using commercial tests produced by Boehringer (Mannheim, FRG). The time of postexercise blood [NHs]pl and [la-]b measurements was chosen based on the data reported by Buono et al. (1984) and Graham et al. (1990) showing the highest concentrations of these metabolites between the 2nd and 4th min following the termination of exercise. The field running tests were performed on a track on separate days. Each subject was timed for runs of 30, 60 and 600 (girls) or 1000 (boys) m. The running performance was expressed as the time (s) required to complete the distance. The differences between groups and between the pre- and postexercise values within the groups were evaluated by independent and dependent Student's t-tests, respectively. In addition, linear regressions and correlation coefficients were calculated by the conventional least square method.
Table 1. Physical characteristics of subjects Group
Age (years)
Body mass (kg)
Height (cm)
BMI (kg.m-:)
Girls Swimmers n=5 Athletes n = 15
mean SD mean SD
13.2 0.3 13.6 0.3
46.6 3.1 49.7 5.7
162.6 3.2 164.2 5.3
17.9 0.5 18.6 1.8
Boys Swimmers n=3 Athletes n = 11 Untrained n=8
mean SD mean SD mean SD
13.4 0.2 13.3 0.3 13.3 0.3
54.2 4.5 54.0 4.8 44.1" 8.7
169.0 5.6 168.1 5.7 155.9"* 7.9
18.9 0.4 19.0 1.0 18.0 1.9
BMI, Body Mass Index calculated as body mass (kg) divided by square of height (m). * P < . 0 5 , ** P
Eur J Appl Physiol (1992) 65:246-250
Europe.n Joumal of
and Occupational Physiology © Springer-Verlag 1992
Relationship between plasma ammonia and blood lactate concentrations after maximal treadmill exercise in circumpubertal girls and boys K. Nazar I, B. Dobrzyfiski 2, and R. Lewicki 3 ] Department of Applied Physiology,Medical Research Centre, Polish Academyof Sciences, 17 Jazgarzewska Str., 00-730 Warsaw, Poland 2 Institute of Sport, Warsaw, Poland 3 Department of Sports Medicine, MilitarySchool of Medicine, L6d~, Poland Accepted April 27, 1992
Summary. The purpose of the study was to define a relationship between plasma ammonia [NH3]pl and blood lactate concentrations [la-]b after exercise in children and to find out whether the [NH3]pb determined during laboratory treadmill tests, may be useful as a predictor of the children's sprint running ability. A group of 20 girls and 14 boys trained in athletics or swimming and 8 untrained boys, aged 13.2 to 13.7 years, participated in the study. Their [NH3]pl and [la-]b were measured before and after incremental maximal treadmill exercise. In addition, the subjects' running performance was tested in 30-, 60- and 600- or 1000-m runs under field conditions. The [NH3]pl during the treadmill runs increased by 20.1 (SD 17.3), 24 (SD 16.7) and 10 (SD 4.3) ~mol. 1- ~ in the girls, the trained boys and the untrained boys, respectively. The postexercise [NH3]p~ correlated positively with [la-]b (r= 0.565 in the girls and 0.812 in the boys) and treadmill speed attained during the test (r = 0.489 in the girls and 0.490 in the boys). Significant correlations were also found between [NH3]N obtained during the treadmill test and the times of 30- and 60-m runs (r= -0.676 and -0.648, respectively) in the boys but not in the girls. A comparison of the present data with those reported previously in adults showed that increases in [NH3]N during maximal exercise in children would seem to be lower than in adult subjects both in absolute values and in relation to [la-]b. The present data would also suggest that [NH3]pl reflects involvement of anaerobic processes during maximal treadmill exercise in circumpubertal children but it has a small practical value for predictiton of their sprint running ability. Key words: Children - Exercise - Ammonia - Lactate Running performance
Correspondence to: K. Nazar
Introduction Maximal anaerobic power and capacity of children, even when normalized for body mass or active muscle mass, have been shown to increase with age and maturation (e.g. Blimke et al. 1988; Crielaard and Pirnay 1985; Inbar and Bar-Or 1986; Vandenwalle et al. 1989). The unique biochemical studies on muscle biopsies taken from exercising children have revealed that the rates of glycogen utilisation and lactate production during maximal exercise in prepubescent boys are lower than those in adolescents and young adults (Ericsson 1980; Ericsson et al. 1973; Ericsson and Saltin 1974). It has also been shown that the activity of muscle phosphofructokinase, considered as a rate-limiting enzyme in glycolysis, increases with age (Ericsson and Saltin 1974). Muscles of young children have, therefore, lower glycolytic potential than those of older age groups. This is in line with the results of several studies which have demonstrated relatively low blood lactate ([la-],; Astrand 1952; Mero 1988; Paterson et al. 1986) and hydrogen ion (Gaisl and Buchberger 1977; Kinderman et al. 1975) concentrations after all-out efforts in pre-adolescents. Studies with adult human subjects have demonstrated that during high-intensity exercise an increase in [la-]b is accompanied by an increase in the plasma ammonia concentration ([NH3]pl; Babij et al. 1983; Buono et al. 1984; Dudley et al. 1983; Eriksson et al. 1985; Hageloch et al. 1990; Schlicht et al. 1990; Schwarke et al. 1987; Wilkerson et al. 1977). The changes in this metabolite concentration and their relationship to [la-]b have not been studied thoroughly in children. Thus, the aim of the present investigation was to define a relationship between [la-]b and [NH3]pl measured simultaneously after maximal exercise in circumpubertal girls and boys. Since NH3 during intensive exercise is produced mainly in fast twitch fibres (Tullson and Terjung 1990; Weicker et al. 1990) an attempt was also made to find out whether the [NH3lpl attained during incremental maximal exercise tests correlates with subjects' running performance on a treadmill and in short distance runs under field conditions.
247
Methods
Subjects. A group of 20 girls and 22 boys, aged 13.2-13.7 years, participated in this study. Informed consent, parental permission and medical clearance were obtained for all subjects. The study group included: elite junior swimmers (5 girls and 3 boys) who had been training in swimming for 5-6 years (18 h per week), "athletes" (15 girls and 11 boys) all practising diverse forms of athletics such as running at various distances, and jumping, etc. without specialisation for 3 years (12 h per week) and 8 untrained boys who participated only in the school physical education programme (2 h per week). The subjects' physical characteristics are listed in Table 1. Only 3 girls (1 swimmer and 2 athletes) attained menarche prior to the test, 8 girls (3 swimmers and 5 athletes) were at Tanner stage II and the remaining ones at stage I. Among boys, 13 were at Tanner stage II (2 swimmers, 8 athletes and 5 untrained) whereas the remaining 9 boys were at stage I. Treadmill tests were performed always in the morning, 2-3 h after a light meal consisting mainly of carbohydrate, at ambient
temperatures of 21-24°C and relative humidities of 55°70-60°7o. The subjects ran on a treadmill (Jaeger, FRG) at 0% gradient. The starting speed of 7.2 k m . h -1 was increased by 1.8 k m . h -1 every 2 min until the subjects reported exhaustion. Before the run and 3 min after its cessation blood was taken from the antecubital vein for [NH3]pIdetermination. The [la-]b was estimated in the arterialized blood taken from a fingertip at the same times. Both metabolites were measured using commercial tests produced by Boehringer (Mannheim, FRG). The time of postexercise blood [NHs]pl and [la-]b measurements was chosen based on the data reported by Buono et al. (1984) and Graham et al. (1990) showing the highest concentrations of these metabolites between the 2nd and 4th min following the termination of exercise. The field running tests were performed on a track on separate days. Each subject was timed for runs of 30, 60 and 600 (girls) or 1000 (boys) m. The running performance was expressed as the time (s) required to complete the distance. The differences between groups and between the pre- and postexercise values within the groups were evaluated by independent and dependent Student's t-tests, respectively. In addition, linear regressions and correlation coefficients were calculated by the conventional least square method.
Table 1. Physical characteristics of subjects Group
Age (years)
Body mass (kg)
Height (cm)
BMI (kg.m-:)
Girls Swimmers n=5 Athletes n = 15
mean SD mean SD
13.2 0.3 13.6 0.3
46.6 3.1 49.7 5.7
162.6 3.2 164.2 5.3
17.9 0.5 18.6 1.8
Boys Swimmers n=3 Athletes n = 11 Untrained n=8
mean SD mean SD mean SD
13.4 0.2 13.3 0.3 13.3 0.3
54.2 4.5 54.0 4.8 44.1" 8.7
169.0 5.6 168.1 5.7 155.9"* 7.9
18.9 0.4 19.0 1.0 18.0 1.9
BMI, Body Mass Index calculated as body mass (kg) divided by square of height (m). * P < . 0 5 , ** P
