Acta physiol. scand. 1975. 94. 313-318 From the Department of Physiology, Gymnastik- och idrottshogskolan, Stockholm. Sweden
Enzyme Activities and Muscle Strength after “Sprint Training” in Man BY A. THORSTENSSON, B. SJODINand J. KARLSSON Received 15 November 1974
Abstract THORSTENSSON, A., B. SJODIN,and J. KARLSSON. Enzyme activities and muscle strength after “sprint training” in man. Acta physiol. scand. 1975. 94. 313-318. Sprint type strength training was performed 3-4 times a week for 8 weeks by 4 healthy male students (1618 yrs). The training was carried out on a treadmill at high speed and with high inclination. Muscle biopsies were obtained from vastus lateralis before and after the training period for histochemical classification of slow and fast twitch muscle fibres and for biochemical determination of metabolites and enzyme activities. Muscle fibre type distribution was unchanged, whereas fibre area indicated an increase for both fibre types in 3 subjects after training. The muscle enzyme activities of Mgz+ stimulated ATPase, myokinase and creatine phosphokinase increased 30, 20, and 36 percent, respectively. Muscle concentration of ATP and creatine phosphate (CP) did not change with training. Sargent’s jump increased with on average 4 cm (from 47 to 51 cm), maximal voluntary contraction (MVC) with 19 kp (from 165 to 184 kp), and endurance a t 50 percent of MVC with 9 s (from 47 to 56 s), respectively. After training all subjects showed a gain in body weight (mean 1.4 kg) and in thigh circumference (mean 1.5 cm) indicating a larger leg muscle volume and consequently also an increase in total ATP and CP.
High intensity exercise of short duration will apply high demands on the immediate energy supplying mechanisms in the muscle, and repeated exercise of this type has been shown to cause exhaustion of phosphagen stores in the exercising muscles (Karlsson and Saltin 1971). Animal studies have demonstrated that short term high intensity training programs cause an increase in creatine phosphokinase activity (Staudte, Exner, and Pette 1973), and an increased storage of creatine phosphate has been indicated after sprint training of rats at high altitude (Gale and Nagle 1971). The aim of the present study was to investigate quantitatively and qualitatively the effects of a high intensity intermittent sprint training program on skeletal muscle in man. Special interest was focused on the turn-over mechanisms of ATP by examining the activities of actomyosin ATPase (E.C.3.6.1.3.), creatine phosphokinase, CPK (E.C.2.7.3.2.), and rnyokinase, MK (E.C.2.7.4.3.), as well as the size of the phosphagen stores before and after the training period. In addition histological analyses were performed to evaluate changes in muscle fibre type composition. 313
314
A. THORSTENSSON, B. SJODIN AND J. KARLSSON
Material and Methods Subjects: 4 healthy, moderately trained male students (16-18 yrs), participated in the study. Although the subjects were in late adolescence, growth effects are assumed to be insignificant due to the short observation period. No increase in body height was observed during the period. Training procedure: The subjects were training 3 to 4 times a week over a period of 8 weeks. The training bouts were performed as short term intermittent sprint training ( 5 s running) o n a motordriven treadmill a t high speed and with steep inclination. The rest periods between each bout were 25-55 s. Over the training period the speed, inclination and number of repetitions were successively increased from on average 19 km/h, 9", and 20 repetitions per bout t o 24 km/h, lo", and 40 repetitions per bout. The basis for these gradual increases in training load and intensity was to force the subjects to approximately the same level of exhaustion after each training session as the training program proceeded and the capability of the subjects improved. Although sprint training from a practical point of view is a well known procedure it was thought of interest to further define the protocol applied. Therefore Vo,, H R , and blood lactate concentration were determined a t appropriate intervals during one training session (subject H. 0. 100 x 5 s, speed: 24 km/h, inclination: 1 I", rest periods: 55 s), using standard procedures employed in our laboratory (see e.g. Christensen et al. 1960).
All tests and analyses were carried out before the start of the training and 2 days after the termination of the training period according to the same protocol. Functional and anthropometrical tests: The dynamic strength in the legs was assessed by means of Sargent's jump, i.e. vertical jumps from a squatted position, and by Margaria test (Margaria, Aghemo and Rovelli 1966), i.e. running at maximal speed in a staircase with 36 cm step height and 33" inclination. The isometric leg strength was measured as maximal voluntary isometric contraction (MVC) and as endurance time a t 50% of MVC (Karlsson and Ollander 1972). Sprint acceleration tests over 25 m were performed using conventional sprint starting positions. The timing in the sprint and in the Margaria test was done with 0.001 s accuracy o n a digital timer (TF 2414/1,Markoni Instrument Ltd). Individual maximal oxygen uptakes (3, max) were determined on a bicycle ergometer. Expired air was collected in Douglas bags and gas analyses were carried out on a Haldane apparatus (Astrand and Saltin 1961). To evaluate gross anthropometrical changes due to the training body weight, height, and thigh circumference of both legs were determined. Thigh girth was measured in a horizontal plane just below the lowest point in the gluteal furrow. Biochemical and histochemical anaiyses: Muscle biopsies were obtained from the lateral portion of the thigh (m. vastus lateralis) (Bergstrom 1962). The biopsies for the metabolite and enzyme activity analyses were immediately frozen in liquid nitrogen (within 3-4 s), and stored at - 80°C. The enzyme activities of Mgz+ stimulated myofibrillar ATPase, CPK, MK, and lactate dehydrogenase, LD H (E.C.1.1.1.27.),as well as the concentrations of ATP and creatine phosphate (CP)in the muscle were determined according to the Lowry techniques (Lowry and Passonneau 1972) as modified in our laboratory by Karlsson (1971). The biopsies for the histochemical studies were mounted and frozen in isopentane. Sections of 10 ,um were cut and stained for identification of slow twitch (ST) and fast twitch (FT) muscle fibres and estimation of fibre area (for ref. see Gollnick et ai. 1972). To assess fibre recruitment pattern during this extreme type of exercise selective glycogen depletion was evaluated by means of PAS staining (Gollnick et al. 1974 a) of biopsy specimens obtained before and after the training session described above (subject H. 0.). Statistical methods: Ordinary statistical methods were applied for calculation of mean values and standard error of the means. Intraindividual differences between values before and after training were tested by the Student's t-test. In testing hypothesis one-tailed tests have been used (Ferguson 1966,Siege1 1956).
Results The results from the single training session (Fig. 1) are in general agreement with what has previously been reported for similar intermittent exercise (Christensen et at. 1960, Saltin and EssCn 1971). Vo, during activity averaged 2.8 l/min or approximately 70% of V,, max,
SPRINT TRAINING AND MUSCLE ENZYMES Subject H.O. 100 . 5
s e ~ [24 .
315 km/h , It' inch] 55 sec rest
Fig. 1. Oxygen uptake, heart rate and blood lactate concentration for subject H. 0. performing 100 x 5 s sprint running (rest intervals 55 s) with a speed of 24 km/h and an inclination of II", presented in absolute figures and in percent of maximal values.
whereas the corresponding value for the rest periods was 2.0 l/min. Blood lactate after every 10th run ranged 4.3-6.7 mM with a mean of 5.6 mM. The relatively high lactates might be related to the fact that the exercise intensity in the present experiment exceeded that applied by e.g. Saltin and EssCn (1971). Both ST and FT fibres showed glycogen depletion after the training session. This indicates that both fibre types were recruited to produce muscle tension during the sprint type exercise performed in the present study. All subjects demonstrated increases in body weight (mean value 1.4 kg) after the training period, whereas no changes in height were observed (Table I). Simultaneously there was an increase in thigh circumference with on average 1.5 cm (Table I). This indicates that the increase in body weight, at least partly, was attributable to a n augmented leg muscle mass. Increases in MVC, Sargent's jump and endurance at 50% MVC were demonstrated for all subjects, whereas 3 subjects improved their performance in the Margaria and the sprint tests (Table 11). Consequently the sprint training program improved not only dynamic but also isometric performance. The relative distribution of fibre types was not altered as a result TABLE I. Anthropometrical and histological measurements and muscle phosphagen concentrations before and after 8 weeks of sprint training, and intraindividual differences (d), presented as means and standard error of means (S.E.), and the probability (p) of finding a t-value more extreme than the observed under the null-hypothesis. (ns = p > 0.1 .) (n = 4.) Before Body weight, kg Body height, cm Thigh girth, cm FT, % Fibre area, ,urna ST FT V,, max, ml x k g l x min-I ATP, mmol x g-' CP, mmol x g-'
66.4+ 3.20 179.0k3.67' 53.0k1.60
59 k 7 . 3 5 060 k233.4 5 500 k283.2 53.7k2.05 5.1k0.30 19.9k0.72
After
d
P
67.8+ 3.12 179.1k3.63 54.5_c 1 .I I 56 k 7 . 4 5 190 k183.8 5740 k316.1 55.4k2.35 5.4k0.26 17.5k0.59
1.4 0.22 0.1 +O. 13 l.5+0.51 3 k2.1 130 k244.0 240 L446.4 1.7k 1.18 0.3k0.22 2.4k 1.75
+
< 0.01
ns < 0.05 ns ns ns ns ns ns
316
A. THORSTENSSON,
B. SJODIN AND J. KARLSSON
TABLE 11. Functional tests before and after 8 weeks of sprint training, presented as in Table I. (n=4.)
MVC, kp
50% MVC, sec Sargent's jump, cm Margaria test, kpmx s-l 25 m sprint, sec
Before
After
d
165k 11.5 47f 3.4 47k2.3 107.9k3.98 3.78k0.079
184+ 20.6 56k2.4 5151.6 112.5+ 3.25 3.75 50.063
19.0i9.23 9f 3.78 4f 1.36 4.6t2.32 0.032 0.018
P
10.1 i 0.05
< 0.05 c0.1
Enzyme Activities and Muscle Strength after “Sprint Training” in Man BY A. THORSTENSSON, B. SJODINand J. KARLSSON Received 15 November 1974
Abstract THORSTENSSON, A., B. SJODIN,and J. KARLSSON. Enzyme activities and muscle strength after “sprint training” in man. Acta physiol. scand. 1975. 94. 313-318. Sprint type strength training was performed 3-4 times a week for 8 weeks by 4 healthy male students (1618 yrs). The training was carried out on a treadmill at high speed and with high inclination. Muscle biopsies were obtained from vastus lateralis before and after the training period for histochemical classification of slow and fast twitch muscle fibres and for biochemical determination of metabolites and enzyme activities. Muscle fibre type distribution was unchanged, whereas fibre area indicated an increase for both fibre types in 3 subjects after training. The muscle enzyme activities of Mgz+ stimulated ATPase, myokinase and creatine phosphokinase increased 30, 20, and 36 percent, respectively. Muscle concentration of ATP and creatine phosphate (CP) did not change with training. Sargent’s jump increased with on average 4 cm (from 47 to 51 cm), maximal voluntary contraction (MVC) with 19 kp (from 165 to 184 kp), and endurance a t 50 percent of MVC with 9 s (from 47 to 56 s), respectively. After training all subjects showed a gain in body weight (mean 1.4 kg) and in thigh circumference (mean 1.5 cm) indicating a larger leg muscle volume and consequently also an increase in total ATP and CP.
High intensity exercise of short duration will apply high demands on the immediate energy supplying mechanisms in the muscle, and repeated exercise of this type has been shown to cause exhaustion of phosphagen stores in the exercising muscles (Karlsson and Saltin 1971). Animal studies have demonstrated that short term high intensity training programs cause an increase in creatine phosphokinase activity (Staudte, Exner, and Pette 1973), and an increased storage of creatine phosphate has been indicated after sprint training of rats at high altitude (Gale and Nagle 1971). The aim of the present study was to investigate quantitatively and qualitatively the effects of a high intensity intermittent sprint training program on skeletal muscle in man. Special interest was focused on the turn-over mechanisms of ATP by examining the activities of actomyosin ATPase (E.C.3.6.1.3.), creatine phosphokinase, CPK (E.C.2.7.3.2.), and rnyokinase, MK (E.C.2.7.4.3.), as well as the size of the phosphagen stores before and after the training period. In addition histological analyses were performed to evaluate changes in muscle fibre type composition. 313
314
A. THORSTENSSON, B. SJODIN AND J. KARLSSON
Material and Methods Subjects: 4 healthy, moderately trained male students (16-18 yrs), participated in the study. Although the subjects were in late adolescence, growth effects are assumed to be insignificant due to the short observation period. No increase in body height was observed during the period. Training procedure: The subjects were training 3 to 4 times a week over a period of 8 weeks. The training bouts were performed as short term intermittent sprint training ( 5 s running) o n a motordriven treadmill a t high speed and with steep inclination. The rest periods between each bout were 25-55 s. Over the training period the speed, inclination and number of repetitions were successively increased from on average 19 km/h, 9", and 20 repetitions per bout t o 24 km/h, lo", and 40 repetitions per bout. The basis for these gradual increases in training load and intensity was to force the subjects to approximately the same level of exhaustion after each training session as the training program proceeded and the capability of the subjects improved. Although sprint training from a practical point of view is a well known procedure it was thought of interest to further define the protocol applied. Therefore Vo,, H R , and blood lactate concentration were determined a t appropriate intervals during one training session (subject H. 0. 100 x 5 s, speed: 24 km/h, inclination: 1 I", rest periods: 55 s), using standard procedures employed in our laboratory (see e.g. Christensen et al. 1960).
All tests and analyses were carried out before the start of the training and 2 days after the termination of the training period according to the same protocol. Functional and anthropometrical tests: The dynamic strength in the legs was assessed by means of Sargent's jump, i.e. vertical jumps from a squatted position, and by Margaria test (Margaria, Aghemo and Rovelli 1966), i.e. running at maximal speed in a staircase with 36 cm step height and 33" inclination. The isometric leg strength was measured as maximal voluntary isometric contraction (MVC) and as endurance time a t 50% of MVC (Karlsson and Ollander 1972). Sprint acceleration tests over 25 m were performed using conventional sprint starting positions. The timing in the sprint and in the Margaria test was done with 0.001 s accuracy o n a digital timer (TF 2414/1,Markoni Instrument Ltd). Individual maximal oxygen uptakes (3, max) were determined on a bicycle ergometer. Expired air was collected in Douglas bags and gas analyses were carried out on a Haldane apparatus (Astrand and Saltin 1961). To evaluate gross anthropometrical changes due to the training body weight, height, and thigh circumference of both legs were determined. Thigh girth was measured in a horizontal plane just below the lowest point in the gluteal furrow. Biochemical and histochemical anaiyses: Muscle biopsies were obtained from the lateral portion of the thigh (m. vastus lateralis) (Bergstrom 1962). The biopsies for the metabolite and enzyme activity analyses were immediately frozen in liquid nitrogen (within 3-4 s), and stored at - 80°C. The enzyme activities of Mgz+ stimulated myofibrillar ATPase, CPK, MK, and lactate dehydrogenase, LD H (E.C.1.1.1.27.),as well as the concentrations of ATP and creatine phosphate (CP)in the muscle were determined according to the Lowry techniques (Lowry and Passonneau 1972) as modified in our laboratory by Karlsson (1971). The biopsies for the histochemical studies were mounted and frozen in isopentane. Sections of 10 ,um were cut and stained for identification of slow twitch (ST) and fast twitch (FT) muscle fibres and estimation of fibre area (for ref. see Gollnick et ai. 1972). To assess fibre recruitment pattern during this extreme type of exercise selective glycogen depletion was evaluated by means of PAS staining (Gollnick et al. 1974 a) of biopsy specimens obtained before and after the training session described above (subject H. 0.). Statistical methods: Ordinary statistical methods were applied for calculation of mean values and standard error of the means. Intraindividual differences between values before and after training were tested by the Student's t-test. In testing hypothesis one-tailed tests have been used (Ferguson 1966,Siege1 1956).
Results The results from the single training session (Fig. 1) are in general agreement with what has previously been reported for similar intermittent exercise (Christensen et at. 1960, Saltin and EssCn 1971). Vo, during activity averaged 2.8 l/min or approximately 70% of V,, max,
SPRINT TRAINING AND MUSCLE ENZYMES Subject H.O. 100 . 5
s e ~ [24 .
315 km/h , It' inch] 55 sec rest
Fig. 1. Oxygen uptake, heart rate and blood lactate concentration for subject H. 0. performing 100 x 5 s sprint running (rest intervals 55 s) with a speed of 24 km/h and an inclination of II", presented in absolute figures and in percent of maximal values.
whereas the corresponding value for the rest periods was 2.0 l/min. Blood lactate after every 10th run ranged 4.3-6.7 mM with a mean of 5.6 mM. The relatively high lactates might be related to the fact that the exercise intensity in the present experiment exceeded that applied by e.g. Saltin and EssCn (1971). Both ST and FT fibres showed glycogen depletion after the training session. This indicates that both fibre types were recruited to produce muscle tension during the sprint type exercise performed in the present study. All subjects demonstrated increases in body weight (mean value 1.4 kg) after the training period, whereas no changes in height were observed (Table I). Simultaneously there was an increase in thigh circumference with on average 1.5 cm (Table I). This indicates that the increase in body weight, at least partly, was attributable to a n augmented leg muscle mass. Increases in MVC, Sargent's jump and endurance at 50% MVC were demonstrated for all subjects, whereas 3 subjects improved their performance in the Margaria and the sprint tests (Table 11). Consequently the sprint training program improved not only dynamic but also isometric performance. The relative distribution of fibre types was not altered as a result TABLE I. Anthropometrical and histological measurements and muscle phosphagen concentrations before and after 8 weeks of sprint training, and intraindividual differences (d), presented as means and standard error of means (S.E.), and the probability (p) of finding a t-value more extreme than the observed under the null-hypothesis. (ns = p > 0.1 .) (n = 4.) Before Body weight, kg Body height, cm Thigh girth, cm FT, % Fibre area, ,urna ST FT V,, max, ml x k g l x min-I ATP, mmol x g-' CP, mmol x g-'
66.4+ 3.20 179.0k3.67' 53.0k1.60
59 k 7 . 3 5 060 k233.4 5 500 k283.2 53.7k2.05 5.1k0.30 19.9k0.72
After
d
P
67.8+ 3.12 179.1k3.63 54.5_c 1 .I I 56 k 7 . 4 5 190 k183.8 5740 k316.1 55.4k2.35 5.4k0.26 17.5k0.59
1.4 0.22 0.1 +O. 13 l.5+0.51 3 k2.1 130 k244.0 240 L446.4 1.7k 1.18 0.3k0.22 2.4k 1.75
+
< 0.01
ns < 0.05 ns ns ns ns ns ns
316
A. THORSTENSSON,
B. SJODIN AND J. KARLSSON
TABLE 11. Functional tests before and after 8 weeks of sprint training, presented as in Table I. (n=4.)
MVC, kp
50% MVC, sec Sargent's jump, cm Margaria test, kpmx s-l 25 m sprint, sec
Before
After
d
165k 11.5 47f 3.4 47k2.3 107.9k3.98 3.78k0.079
184+ 20.6 56k2.4 5151.6 112.5+ 3.25 3.75 50.063
19.0i9.23 9f 3.78 4f 1.36 4.6t2.32 0.032 0.018
P
10.1 i 0.05
< 0.05 c0.1
