125
Comparison of Various Exercise Tests with Endurance Performance during Soccer in Professional Players J. Bangsbo, F. Lindquisi
Abstract J. Bangsbo and F. Lindquist, Comparison of
Various Exercise Tests with Endurance Performance during Soccer in Professional Players. mt j Sports Med, Vol 13,No2,pp125—132,1992.
km; range: 14.8—18.5 km) was not related to match-distance (r = 0.16), however, its correlation coefficient with high intensity distance covered during the match was 0.70. The interval field test distance was strongly correlated (r = 0.83) with the distance covered during the prolonged, intermittent test distance. VO2max (r = 0.64) and blood
concentrations during submaximal running (r 0.58) were related to match-distance, but not to the prolonged intermittent test distance (r = 0.18 and r = 0.27, lactate
Accepted after revision: April 17, 1991
To evaluate exercise procedures to test the en-
durance capacity during soccer, individual results in laboratory and field tests were compared to physical performance during the match and further to performance
during long term, intermittent exercise. Twenty professional soccer players were video-taped during competitive soccer matches, and the longest total distance (match-
distance) and high intensity distance were determined. Blood lactate and maximum oxygen uptake (VO2max) were measured during treadmill running. The subjects also carried out a continuous and an interval field test. Furthermore, eight players performed a prolonged, soccer-specif-
ic, intermittent test to exhaustion. Muscle enzymes and morphological characteristics were determined in biopsy
samples obtained from the m. gastrocnemius. The distance covered during the prolonged, intermittent test (mean: 16.3
Introduction
During a 90-mm soccer match the total distance covered by elite-players is between 9 and 14 km, the mean work rate is about 75% of maximum oxygen uptake, and the glycogen content in the leg muscles is low at the end of the match (3, 7, 15, 25). The mode of exercise is intermittent and blood lactate concentrations in the range of 6—12 mmol 1 are often found during the soccer match (3, 7). Thus, a soccer player needs a well-developed ability to perform high intensity activities frequently during long term exercise. A lack of this physical capacity may limit the performance of a player during soccer matches. Therefore, it is important to test this capability, which will be referred to as the soccer-specific endurance capacity. To be useful, such a test must have a high valid-
ity, which can be demonstrated by a strong relationship between the test results and the physical performance of players lnt.J. SportsMed. 13(1992)125—132 Georg Thieme Verlag Stuttgart New York
respectively). The muscle enzyme activities and the morphological variables were not related to match activities nor to prolonged, intermittent exercise performance. The present data suggest that the interval field test can be used to evaluate long term, intermittent exercise performance and perhaps to test the endurance performance of soccer play-
ers, and that for well-trained athletes muscle characteristics, VO2max and blood lactate concentration during submaximal running are not sensitive measurements of endurance capacity during intermittent exercise. Key words
Testing, soccer, performance, lactate, muscle enzymes
during matches. This comparison is complicated by the fact that a single measurement obtained from match analysis may not express the soccer-specific endurance capacity. Furthermore, the true physical ability of a player may not be demonstrated in any given match due to, for example, tactical limitations (3). Nevertheless, evidence from several match analyses suggests that high-intensity distance covered might be a reliable measure for endurance performance during a match (3). An alternative possibility is to compare test results with performance during long term, intermittent running to exhaustion, with a pattern of exercise similar to soccer. The physical capacity of soccer players has been determined by different test procedures (8, 12, 21). However, the test results were not related to individual performances in either long term, intermittent exercise or the match.
Physical training increases fat-oxidation, lowers blood lactate concentration during exercise and improves endurance performance of long term, continuous exercise. These changes are related to an increase in the maximum oxygen uptake, the number of capillaries, and the activity of
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August Krogh Institute, Copenhagen, Denmark
126 Int.J.SportsMed. 13(1992)
J. Bangsbo, F. Lindquist Table 1 Age, weight, height, VO2max and years of playing soccer for the subjects Weight kg
Age
yrs
Group A
VO2max Height cm mimin 1kg
Years of soccer 1
yrs All
Top-level
22.3
76.3
182.9
60.4
15.1
4.2
24.9
74.9
182.1
61.2
17.8
6.4
(n=8) Group B
(n=12) Values are mean Scheme of the experimental design. (n): number of sub-
Fig. 1
jects.
uate intermittent exercise endurance capacity and physical
Field running
Jit I Treadmill A
I-
0
60
46
running B
95
nin
A
kmr1
The purpose of the present study was to evaluate the effectiveness of various procedures to determine the potential physical soccer capacity. Twenty elite soccer players performed laboratory and field tests, and the results were compared to the physical performance during matches and to the muscle characteristics (Fig. 1). Methods
25
Subjects 18
Twenty male professional soccer players
171
belonging to three of the top-class teams in Denmark were studied. Eight of these (group A) took part in all tests, and in the middle of the experimental period a muscle biopsy was
15
0_ 0
2
taken from the m. gastrocnemius of these players (Fig. 1). The remaining 12 players are referred to as group B. The physical 3
1.
5mm
B k m - h1
characteristics of the subjects are presented in Table 1. The total number of years the players had been playing soccer ranged from 12 to 21 yrs, with at least two years at the Danish top-level. The subjects were informed about possible risks involved in this study before they gave their verbal consent to participate.
Procedures
__ ___ r'' —r'/____ "/ —1---"
95
Fig.
2
—r—1"
02
109
113
120
I
l27mir,
Protocol of the intermittent endurance test. The test con-
sisted of 46 mm intermittent field running, follow by 14 mm of rest and, then, intermittent treadmill running to exhaustion divided in two parts (A and B) (upper panel). The duration of A was 35 mm and it consisted of 7 identical intermittent exercise periods (middle panel), and durin part B (lower panel) treadmill speed alternated between 8 kmh (later l2kmh ) for lOs () and 18 km h1forl5s(E), which continued until exhaustion. For further explanation see "Methods".
The experiment, including filming and testing, was carried out over a six-week period in the middle of the second part of the season. The tests were done on separate days, and the subjects were familiarized with the testing procedures before starting the experiment.
Match distances: Each of the 20 players was filmed by a separate camera during at least two complete matches played on his home ground in the Danish National League, and the video tapes were later replayed on a television
monitor and coded for ten match activities. The essential aspects of the technique used for match analysis have been described earlier (3). The longest total distance covered by an individual during the observed matches was called "match-dis-
tance", and "high-intensity distance" was defined as the the enzymes in the tricarboxylic acid cycle, and 3-oxidation in
largest distance covered by moderate speed running
the trained musculature (1, 14, 19, 23). The training-induced decrease in blood lactate concentration during submaximal
speed: 15 kmh'), high-speed running (18 kmh ) and
exercise in association with the increase in performance, makes lactate measurements useful for prediction of long term, continuous exercise performance (10, 16). Whether maximum oxygen uptake or blood lactate can be used to eval-
sprint running (30 km-h 1) Intermittent
endurance test: The players in
group A carried out a prolonged, intermittent test to exhaustion (intermittent endurance test — Fig. 2). First the players per-
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performance during a soccer match is less certain.
INTERVAL El ELD TEST
INTERVAL TREADMILL TEST
TREDMiLLLOW SPEED
(High Rest
krs
2
2
iI 5 5
5
7
H
mt. J. Sports Med. 13(1992) 127 lISP
liSsI
—
LOW IlOol ID
kr.h o
7(
Blood
—. o—, V02
side stepping
LI:
6
Fig. 3 Protocol of the interval treadmill test. The test consisted of 8 intermittent exercise bouts interspersed by rest periods of progressive increased length (upper panel). During each exercise bout the
treadmill speed alternated between 8 kmh1for lOs () and a higher speed for 15 s (LI). At the lower panel 18 km h 1is given as an example of the higher speed.
Fig. 4 Course for the interval field test. The duration of the test was 16.5 mm, where the players alternated between high- and low-intensity exercise for 15 and 10 s, respectively. The test started at point A with high intensityexercise.The playersfollowed the outlined route (—3 during the high-intensityexercise periods, which consisted of forward running (40 m), backwards running (8,25 m), forward running (95.25 ml and side-stepping with front away from (825 m) and against the centre (8.25 m). During the low-intensity periods the players jogged to the centre and back to the stop-position.
speed
formed a 46-mm standard field protocol, composed of an 18-
mm warming up period with stretching (total duration: 8:00 mm), low (6:00 mm) and moderate speed running (4:00 mm), the total distance being 1.89km, and two identical 14-mm periods. During the latter the subjects alternated between 8 different activities: Standing (1:35 mm), walking (1:00 mm), jogging (3:5 0 mm), low-speed running 3:15 mm), backwards runfling (0:20 mm), moderate speed running (2:55 mm), highspeed running (0:35 mm), and sprint running (0:30 mm). The total distance covered during the 46 mm was 6856 m. After a 14-mm rest period the subjects first performed intermittent treadmill running for 35 mm (consisting of 7 x 5-mm periods where treadmill speed alternated among 8 different speeds from 0 to 25 kmh '(part A — Fig. 2)). This was followed by intermittent exercise alternating between high-speed running
(18 kmh') for 15 sand low-speed running (8 kmh in the 18 mm) for 10 s, which conbeginning and 12 kmh tinued until the subjects stopped due to exhaustion (part B — Fig. 2). Exhaustion was defined as the point where the subject was no longer able to exercise for 15 s at high intensity. The subjects were verbally encouraged by the test leaders to continue as long as possible. During the treadmill running expired air was regularly collected. The total distance covered was the test result. Seven of the eight players carried out the test twice with different diets on the days prior the test, but only the test result after having ingested their usual diet is reported in the present study (4). Treadmill tests: All 20 players carried out a con-
tinuous test on a motor driven treadmill. The test consisted of five 6-mm exercise bouts and one 3.5-mm bout, separated by rest periods with progressively increased duration (2—5 mm). Treadmill speeds were 6,8, 12, 15, 16.5, and 18 kmh. Sub-
sequently, following a rest period of 10 mm, the subjects completed a maximal test. The initial treadmill speed was 18
kmh , and it was increased 2 kmh every 2 mm until the
subject was exhausted. In addition, group A carried out an interval treadmill test on a different day. The protocol is depicted in Fig. 3. During each 5-mm 50-s exercise period the treadmill
systematically alternated between 8 kmh for 10 s
and a higher speed for 15 s. The high speed was increased from one 5-mm 50-s period to the next, starting with 10 kmh
then 12, 15, 16.5, 18, 20, 22 kmh and ending with, if possible, 24 kmh1. Before each of the treadmill tests a catheter was put into an antecubital vein, and blood samples were obtained immediately after each of the exercise bouts and assayed for lactate concentration. Oxygen uptake (V02) was measured during the last two mm of the submaximal exercise bouts and continuously during the maximal test. During maximal running a clear levelling off of V02 (VO2max) occurred in
all subjects. By graphing an individual's V02 and venous blood lactate concentration obtained at the submaximal running speeds, V02 at a lactate level of 3 mmoll '(V02-lac3) was determined both for the continuous and the interval treadmill test.
Field tests: Group A and six players of group B
performed an interval field test. The course for this test is shown in Fig. 4. The activity alternated between high- and lowintensity exercise for 15 and lOs, respectively. The duration of the test was 16.5 mm. Thus, total durations of high- and low-intensity exercise were 10 and 6.5 mm, respectively. During the high intensity periods the players followed the outlined route
with different locomotion forms (side-stepping, backwards and forward running). The low-intensity periods consisted of 10 s jogging to the centre and back to the stop-position. The test result was the distance covered during the 10 mm of high intensity exercise. Group A and the other six players of group B car-
ried out a continuous field test, which was a slight modification of a previously described procedure (8). The test result was the time required to cover four laps of a track (4 times 540 m). Before both the field tests the subjects warmed up for 15 mm, and immediately after the tests a finger tip blood sample for lactate analysis was taken.
Analysis Expiratory gas was collected in Douglas bags and the volume was measured with a Tissot spirometer. Oxygen (02) and carbon dioxide (C02) concentrations were deter-
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1
Comparison of Various Exercise Tests with Endurance Peiformance during Soccer
128 mt. J. Sports Med. 13 (1992)
J. Bangsbo, F. Lindquist
Table 2 Correlation coefficients for individual relationships between the measured variables Tests
Match-distances
Matchdistance
Intermittent endur. test distance
Field tests Interval Continuous Continuous
Enzymes
VO2max HAD CS
Interval
test distance
16 (8)
.70 (8)
.
lriterv. field test
.38 (14)
.23 (14)
.83*(8)
— .68(14)
—.44 (14)
—.57 (8)
— .78* (8)
VO2-lac301
.58*(20)
.26 (20)
.27 (8)
,69*(14)
— .49 (14)
V02-lac3
.60 (8)
.25 (8)
— .33 (8)
.07 (8)
.13 (8)
.32 (8)
•
•
.64(20)
.40 (20)
.18 (8)
.47 (14)
— .47 (14)
.78*(20)
.00 (8)
.42 (8)
.28 (8)
.06 (8)
— .67 (8)
— .57 (8) — .66 (8)
.
CS
— .63 (8)
—.40 (8)
—.32 (8)
(8)
.20 (8)
— .81* (8)
—.47 (8) — .84*(8)
.60 (8)
(8)
.34 (8)
.49 (8)
.27 (8)
.22 (8)
— .20 (8)
—.13 (8)
.42 (8) — .10 (8)
— .07 (8)
.27 (8)
.23 (8)
.29 (8)
— .23 (8)
— .56 (8)
— .46 (8) — .61 (8)
.21
— .30
.56 (8)
.16 (8)
.65 (8)
. .65 (8)
• .42 (8)
•
*Significant correlation between variables. (n): number of observations.
mined with paramagnetic 02 (Servomex) and infrared C02 (Beckman LB-Il) analysers, respectively. These analysers were regularly calibrated with known concentrations of gas determined by the Scholander technique. The blood samples were placed in ice-cold 0.6 M perchloric acid, centrifuged and the supernatants were frozen at —40 °C. They were analysed for lactate by enzymatic spectrophotometric methods (13).
Muscle biopsies: Muscle biopsies were dissected into two parts. One piece was frozen directly in liquid N2 and used for biochemical analyses. The remaining part was mounted in an embedding medium for histochemical analyses and frozen in isopentane cooled to freezing point. The samples were stored at — 80 °C until analyses were performed. Histochemical analyses: Serial transverse sections ((Im) were cut with a microtome at —20 °C and histochemically stained for myofibrillar ATPase activity (22). Fibre classification into ST, FTa, and FTh fibres was based on myofibrillar ATPase stains after preincubation at pH 4.3, 4.6, and 10.3 (5).
described by Essen-Gustavsson and Henriksson (9). Enzyme
activities were measured at 25 °C and expressed as
imolmin g dry weight. Statistics Standard procedures were used for regression and correlation analysis, and statistical tests were done using Student's t-test. Results
Match-distances The mean match-distance was 10.98 (range: 8.99— 12.65, n = 20) km, of which the high-intensity distance
accounted for 19% or 2.1 (0.6—3.8) km. The match-distance
was related to the high-intensity distance (r=0.6l, n=20, p 0.05) or to high-intensitydistance during a match (r=0.23, n= 14, p>0.05) (Fig. 8). The running time for the
Mean lactate concentrations after the interval and continuous field tests were 7.8 (5.1—12.7) and 11.0 (8.8—
13.6) mmoll respectively. Muscle characteristics
continuous field test averaged 10.44 (9.50—11.95) mm. An in-
The muscle CS and HAD averaged 78.6(65.9—
dividual, inverse relationship (r= —0.68, n= 14, p 0.05) nor the intermittent endurance test distance (r —0.57, n 8, p > 0.05) were correlated to the test result for the continuous field test (Fig. 9).
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km
130 mt. J. Sports Med. 13 (1992)
J. Bangsho, F. Lindquist km
high-intensity distance
high-intensity distance
4 krnf
3
3
2
2
1
r = 0.23
.______________
.
.
r=0.40
km
km 13
match-distance
13
0
5
match-distance
o
S
r=0.38
12
10
r = 0.64 9J
intermittent endurance test
km 18 17 16 15
intermittent endurance test
km V
18
TT 55
60
17
65
r = 0.83
16
0
r=0.18
a
V
15
70 ml kg1min1
0 1.7
0
1.8
\7O2max
1.9
2.0
2.1 km
interval field test
Fig. 7 Individual relationship between VO2max and distance covered during the intermittent endurance test (lower panel), match-distance (middle panel), and high-intensity distance (upper panel) (for def. see Methods).
Fig. 8 Individual relationship between distance covered during the interval field test and distance covered during the intermittent endurance test (lower panel), match-distance (middle panel), and highintensity-distance (upper panel) (for def. see Methods).
— Intermittent endurance
— Intermittent endurance
test distance (km) = \JO2max (ml min1 kg1)
test distance (km) =
interval test distance (km) x 12.2—5.9.
x 0.07+ 12.07.
— Match distance (km) = interval test distance (km) x 3.7+4.0.
— Match-distance (km) = 9O2max (ml min1 kg1) x 0.14+2.65.
— High-intensity-
distance (km) = — High-intensity
distance (km) =
interval test distance (km) x 1.53—0.52.
VO2max (ml min1 kg1) x 0.07 —2.25. since the physical performance during match is influenced by
the intermittent endurance test. CS was inversely correlated to VO2max (r = —0.84, n = 8, p < 0.05) and V02-lac3 for the continuous exercise test (r= —0.81, n 8, p < 0.05) (Table
several factors, e. g. tactical limitations or less than an optimal degree of motivation (3). However, only minor variations are observed in high-intensity distance from match to match, suggesting that it can be used as an indicator of this capacity (3). The high-intensity distance was best correlated to the distance of the prolonged, exhaustive intermittent exercise test (Table 2). The mode of exercise during this test was similar to the exercise pattern used in soccer and the players were accustomed to
2).
performing exhaustive exercise on the treadmill. Thus, the
with 4.67 (3.57—5.97), 4.73 (3.79—5.24) and 4.39 (2.86—5.20)
capillaries around the ST-, FTa-, and FTb-fibre, respectively.
None of these muscle variables were related to match-distance, high-intensity distance, or the distance covered during
Discussion
A single reliable measure of the physical ability
to perform long term, intermittent exercise during a soccer match (the soccer-specific endurance capacity) may not exist,
standardized intermittent endurance test distance might be the best objective measure of the potential physical soccer capacity obtained in the present study.
Increasing the carbohydrate intake above that found in the usual diet of the soccer players has been shown to
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11
Comparison of Various Exercise Tests with Endurance Perjbrmance during Soccer
The intermittent endurance test is time con-
high-intensity distance
km
mt. J. Sports Med. 13(1992) 131
suming and a treadmill is needed. Therefore, for practical pur-
4
D 3
r=0.44 2
.
km 13
linear relationship between the interval field test result and the
match-distance for the three match-players, and by the fact that, in relation to the obtained test result, none of the other players covered a longer match-distance than determined from the relationship among the three match-players (Fig. 8).
match-distance
0
.
12
poses a simple test was desirable. The relationship between performance in the endurance test and the interval field test performance suggests that the latter can be used as a measure of the intermittent endurance capacity and, perhaps, of the soccer-specific endurance capacity. This was supported by a
The usefulness of the interval field test is also supported by the
finding that the mean blood lactate concentration was 7 mmol F after the test. This concentration is of a similar magnitude to that found during the more intense part of soccer
r=0.68=0.68
10
matches (3, 7).
V
intermitlent endurance test km 18 17
0
15.
0
r = 0.57
A
9
10
11
12mm
time continuous field test
Fig. 9 Individual relationship between distance covered during the continuous field test and distance covered during the intermittent endurance test (lower panel), match-distance (middle panel), and high-intensity distance (upper panel) (for def. see Methods). — Intermittent endurance
test distance (kni) =
cont. field test (mm) x (—2.20) + 39.4.
— Match-distance (km) = cont. field test (mm) x (—0.89) + 20.1. — I-Ugh-intensity
distance (km) =
ous treadmill test, expressed as the V02 corresponding to 3 mmol F blood lactate, were correlated to match-distance. However, they were not related to the intermittent endurance performance, and no linear relationship was found between match-distance and V02-lac3 for the match-players (Fig. 7; 0, 0). Likewise, blood lactate concentrations determined during the interval treadmill test were not related to the intermittent endurance test distance. Thus, lactate measurements after continuous or interval submaximal treadmill running
,
+
16
The blood lactate concentration measured after submaximal exercise has been shown to be a good predictor of long term, continuous running performance (see 11, 16). In the present study lactate measurements during the continu-
9
cont. field test (mm) x (—0.57) + 8.0.
the intermittent exercise performance (4). However, the composition of the diet prior to the intermittent endurance
enhance
test in the present study was similar to the usual diet of the play-
ers (4), and they were instructed to maintain their normal diet throughout the study. Thus, the test results should not have been influenced by the diet.
The distance covered during the intermittent endurance test was not correlated to the match-distance. Three of the players (Fig. 5; 0, , D) differed from the remaining five by having a markedly longer match-distance relative to their performance during the prolonged, intermittent test. Apparently only these players were close to their potential maxi-
mal distance during the observed matches. These are called "match-players" in the following discussion.
seem not to be sensitive measures of either the intermittent endurance performance or physical performance during a soccer
match. This conclusion is the same when using any of these data for the blood lactate responses to submaximal continuous or interval running. The blood lactate concentration, and the relative utilization of fat and carbohydrate during submaximal continuous exercise has been associated with the activity of muscle mitochondrial enzymes (17, 19). The magnitude of muscle enzyme activities representing tricarboxylic acid cycle and n-oxidation for the elite soccer players in the present study was similar to values found for endurance-trained athletes and was significantly higher than found in earlier studies of semiprofessional soccer players (2, 18, 20). The variations in the activities of these muscle enzymes within the group were small, and they were not related to the differences in intermittent ex-
ercise performance and blood lactate concentrations during submaximal running. Similarly the muscle morphological data could not explain the difference in performance. Thus, in this group of well-trained athletes, muscle characteristics do not give indices of intermittent endurance performance. As found in other studies (24, 25, 26), a relationship between VO2max and distance covered during the match was established. However, VO2max was not correlated to the distance covered during the intermittent endurance test, and no linear relationship between VO2max and match-distance was found for the match-players (Fig. 7; 0, , El). Thus, VO2max does not seem to be an accurate measure of the soccer-specific endurance capacity. This is in agreement with earlier findings in soccer and other sports (2, 6, 27). Thus, in stu-
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11
mt. J. Sports Med. 13 (1992)
dies of endurance-trained cyclists with similar maximum oxygen uptakes, a great variation in endurance capacity for continuous exercise was observed (6).
In summary, based on the relationship between the distance covered during the intermittent endurance test and the interval field test distance, it seems that the latter can be used to evaluate long term, intermittent exercise performance and, perhaps, the soccer-specific endurance capaci-
ty. The lack of a correlation between the distance covered during the prolonged, intermittent test and performance during a match suggests that all players did not fully utilize this
capacity during the match. Muscle characteristics, VO2max and blood lactate seem not to be sensitive measures of physical performance in soccer. Acknowledgement The study was made possible by grants from Team Danmark and Idruttens Forskningsrâd.
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23 Saltin B., Nazar K., Costili D. L., Stein F., Jansson E., Essén B., Gollnick P. D.: The nature of the training response: Peripheral and central adaptations to one-legged exercise. Acta Physiol Scand 96: 289—305, 1976.
24 Smaros G.: Energy usage during football match, in Verrhiet L. (ed.): Proceedings 1st International Congress on Sports Medicine Applied to Football Volume II. Rome, D. Guanello, 1980. 25 Thomas V., ReillyT.: Application of motion analysis to assess performance in competitive football. Ergonomics 19: 530, 1976. 26 Van Gool D., Van Gerven D., Boutmans J.: The physiological load imposed on soccer players during real match-play, in Reilly T., Lees A., Davids K., Murphy, W. J. (eds.): Science and Football. London/New York, E & F. N. Spon, 1988, pp 51—59. 27 Yoshida T., Udo M., Iwai K., Chida M., Ichioka M., Nakadomo F., Yamaguchi, T.: Significance of the contribution of aerobic and anaerobic components to several distance running performances in female athletes. EurJApplPhysiol6o: 249—253, 1990.
.Jens Bangsbo
August Krogh Institute Universitetsparken 1 3 DK-2100 Copenhagen 0 Denmark
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132
Comparison of Various Exercise Tests with Endurance Performance during Soccer in Professional Players J. Bangsbo, F. Lindquisi
Abstract J. Bangsbo and F. Lindquist, Comparison of
Various Exercise Tests with Endurance Performance during Soccer in Professional Players. mt j Sports Med, Vol 13,No2,pp125—132,1992.
km; range: 14.8—18.5 km) was not related to match-distance (r = 0.16), however, its correlation coefficient with high intensity distance covered during the match was 0.70. The interval field test distance was strongly correlated (r = 0.83) with the distance covered during the prolonged, intermittent test distance. VO2max (r = 0.64) and blood
concentrations during submaximal running (r 0.58) were related to match-distance, but not to the prolonged intermittent test distance (r = 0.18 and r = 0.27, lactate
Accepted after revision: April 17, 1991
To evaluate exercise procedures to test the en-
durance capacity during soccer, individual results in laboratory and field tests were compared to physical performance during the match and further to performance
during long term, intermittent exercise. Twenty professional soccer players were video-taped during competitive soccer matches, and the longest total distance (match-
distance) and high intensity distance were determined. Blood lactate and maximum oxygen uptake (VO2max) were measured during treadmill running. The subjects also carried out a continuous and an interval field test. Furthermore, eight players performed a prolonged, soccer-specif-
ic, intermittent test to exhaustion. Muscle enzymes and morphological characteristics were determined in biopsy
samples obtained from the m. gastrocnemius. The distance covered during the prolonged, intermittent test (mean: 16.3
Introduction
During a 90-mm soccer match the total distance covered by elite-players is between 9 and 14 km, the mean work rate is about 75% of maximum oxygen uptake, and the glycogen content in the leg muscles is low at the end of the match (3, 7, 15, 25). The mode of exercise is intermittent and blood lactate concentrations in the range of 6—12 mmol 1 are often found during the soccer match (3, 7). Thus, a soccer player needs a well-developed ability to perform high intensity activities frequently during long term exercise. A lack of this physical capacity may limit the performance of a player during soccer matches. Therefore, it is important to test this capability, which will be referred to as the soccer-specific endurance capacity. To be useful, such a test must have a high valid-
ity, which can be demonstrated by a strong relationship between the test results and the physical performance of players lnt.J. SportsMed. 13(1992)125—132 Georg Thieme Verlag Stuttgart New York
respectively). The muscle enzyme activities and the morphological variables were not related to match activities nor to prolonged, intermittent exercise performance. The present data suggest that the interval field test can be used to evaluate long term, intermittent exercise performance and perhaps to test the endurance performance of soccer play-
ers, and that for well-trained athletes muscle characteristics, VO2max and blood lactate concentration during submaximal running are not sensitive measurements of endurance capacity during intermittent exercise. Key words
Testing, soccer, performance, lactate, muscle enzymes
during matches. This comparison is complicated by the fact that a single measurement obtained from match analysis may not express the soccer-specific endurance capacity. Furthermore, the true physical ability of a player may not be demonstrated in any given match due to, for example, tactical limitations (3). Nevertheless, evidence from several match analyses suggests that high-intensity distance covered might be a reliable measure for endurance performance during a match (3). An alternative possibility is to compare test results with performance during long term, intermittent running to exhaustion, with a pattern of exercise similar to soccer. The physical capacity of soccer players has been determined by different test procedures (8, 12, 21). However, the test results were not related to individual performances in either long term, intermittent exercise or the match.
Physical training increases fat-oxidation, lowers blood lactate concentration during exercise and improves endurance performance of long term, continuous exercise. These changes are related to an increase in the maximum oxygen uptake, the number of capillaries, and the activity of
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August Krogh Institute, Copenhagen, Denmark
126 Int.J.SportsMed. 13(1992)
J. Bangsbo, F. Lindquist Table 1 Age, weight, height, VO2max and years of playing soccer for the subjects Weight kg
Age
yrs
Group A
VO2max Height cm mimin 1kg
Years of soccer 1
yrs All
Top-level
22.3
76.3
182.9
60.4
15.1
4.2
24.9
74.9
182.1
61.2
17.8
6.4
(n=8) Group B
(n=12) Values are mean Scheme of the experimental design. (n): number of sub-
Fig. 1
jects.
uate intermittent exercise endurance capacity and physical
Field running
Jit I Treadmill A
I-
0
60
46
running B
95
nin
A
kmr1
The purpose of the present study was to evaluate the effectiveness of various procedures to determine the potential physical soccer capacity. Twenty elite soccer players performed laboratory and field tests, and the results were compared to the physical performance during matches and to the muscle characteristics (Fig. 1). Methods
25
Subjects 18
Twenty male professional soccer players
171
belonging to three of the top-class teams in Denmark were studied. Eight of these (group A) took part in all tests, and in the middle of the experimental period a muscle biopsy was
15
0_ 0
2
taken from the m. gastrocnemius of these players (Fig. 1). The remaining 12 players are referred to as group B. The physical 3
1.
5mm
B k m - h1
characteristics of the subjects are presented in Table 1. The total number of years the players had been playing soccer ranged from 12 to 21 yrs, with at least two years at the Danish top-level. The subjects were informed about possible risks involved in this study before they gave their verbal consent to participate.
Procedures
__ ___ r'' —r'/____ "/ —1---"
95
Fig.
2
—r—1"
02
109
113
120
I
l27mir,
Protocol of the intermittent endurance test. The test con-
sisted of 46 mm intermittent field running, follow by 14 mm of rest and, then, intermittent treadmill running to exhaustion divided in two parts (A and B) (upper panel). The duration of A was 35 mm and it consisted of 7 identical intermittent exercise periods (middle panel), and durin part B (lower panel) treadmill speed alternated between 8 kmh (later l2kmh ) for lOs () and 18 km h1forl5s(E), which continued until exhaustion. For further explanation see "Methods".
The experiment, including filming and testing, was carried out over a six-week period in the middle of the second part of the season. The tests were done on separate days, and the subjects were familiarized with the testing procedures before starting the experiment.
Match distances: Each of the 20 players was filmed by a separate camera during at least two complete matches played on his home ground in the Danish National League, and the video tapes were later replayed on a television
monitor and coded for ten match activities. The essential aspects of the technique used for match analysis have been described earlier (3). The longest total distance covered by an individual during the observed matches was called "match-dis-
tance", and "high-intensity distance" was defined as the the enzymes in the tricarboxylic acid cycle, and 3-oxidation in
largest distance covered by moderate speed running
the trained musculature (1, 14, 19, 23). The training-induced decrease in blood lactate concentration during submaximal
speed: 15 kmh'), high-speed running (18 kmh ) and
exercise in association with the increase in performance, makes lactate measurements useful for prediction of long term, continuous exercise performance (10, 16). Whether maximum oxygen uptake or blood lactate can be used to eval-
sprint running (30 km-h 1) Intermittent
endurance test: The players in
group A carried out a prolonged, intermittent test to exhaustion (intermittent endurance test — Fig. 2). First the players per-
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performance during a soccer match is less certain.
INTERVAL El ELD TEST
INTERVAL TREADMILL TEST
TREDMiLLLOW SPEED
(High Rest
krs
2
2
iI 5 5
5
7
H
mt. J. Sports Med. 13(1992) 127 lISP
liSsI
—
LOW IlOol ID
kr.h o
7(
Blood
—. o—, V02
side stepping
LI:
6
Fig. 3 Protocol of the interval treadmill test. The test consisted of 8 intermittent exercise bouts interspersed by rest periods of progressive increased length (upper panel). During each exercise bout the
treadmill speed alternated between 8 kmh1for lOs () and a higher speed for 15 s (LI). At the lower panel 18 km h 1is given as an example of the higher speed.
Fig. 4 Course for the interval field test. The duration of the test was 16.5 mm, where the players alternated between high- and low-intensity exercise for 15 and 10 s, respectively. The test started at point A with high intensityexercise.The playersfollowed the outlined route (—3 during the high-intensityexercise periods, which consisted of forward running (40 m), backwards running (8,25 m), forward running (95.25 ml and side-stepping with front away from (825 m) and against the centre (8.25 m). During the low-intensity periods the players jogged to the centre and back to the stop-position.
speed
formed a 46-mm standard field protocol, composed of an 18-
mm warming up period with stretching (total duration: 8:00 mm), low (6:00 mm) and moderate speed running (4:00 mm), the total distance being 1.89km, and two identical 14-mm periods. During the latter the subjects alternated between 8 different activities: Standing (1:35 mm), walking (1:00 mm), jogging (3:5 0 mm), low-speed running 3:15 mm), backwards runfling (0:20 mm), moderate speed running (2:55 mm), highspeed running (0:35 mm), and sprint running (0:30 mm). The total distance covered during the 46 mm was 6856 m. After a 14-mm rest period the subjects first performed intermittent treadmill running for 35 mm (consisting of 7 x 5-mm periods where treadmill speed alternated among 8 different speeds from 0 to 25 kmh '(part A — Fig. 2)). This was followed by intermittent exercise alternating between high-speed running
(18 kmh') for 15 sand low-speed running (8 kmh in the 18 mm) for 10 s, which conbeginning and 12 kmh tinued until the subjects stopped due to exhaustion (part B — Fig. 2). Exhaustion was defined as the point where the subject was no longer able to exercise for 15 s at high intensity. The subjects were verbally encouraged by the test leaders to continue as long as possible. During the treadmill running expired air was regularly collected. The total distance covered was the test result. Seven of the eight players carried out the test twice with different diets on the days prior the test, but only the test result after having ingested their usual diet is reported in the present study (4). Treadmill tests: All 20 players carried out a con-
tinuous test on a motor driven treadmill. The test consisted of five 6-mm exercise bouts and one 3.5-mm bout, separated by rest periods with progressively increased duration (2—5 mm). Treadmill speeds were 6,8, 12, 15, 16.5, and 18 kmh. Sub-
sequently, following a rest period of 10 mm, the subjects completed a maximal test. The initial treadmill speed was 18
kmh , and it was increased 2 kmh every 2 mm until the
subject was exhausted. In addition, group A carried out an interval treadmill test on a different day. The protocol is depicted in Fig. 3. During each 5-mm 50-s exercise period the treadmill
systematically alternated between 8 kmh for 10 s
and a higher speed for 15 s. The high speed was increased from one 5-mm 50-s period to the next, starting with 10 kmh
then 12, 15, 16.5, 18, 20, 22 kmh and ending with, if possible, 24 kmh1. Before each of the treadmill tests a catheter was put into an antecubital vein, and blood samples were obtained immediately after each of the exercise bouts and assayed for lactate concentration. Oxygen uptake (V02) was measured during the last two mm of the submaximal exercise bouts and continuously during the maximal test. During maximal running a clear levelling off of V02 (VO2max) occurred in
all subjects. By graphing an individual's V02 and venous blood lactate concentration obtained at the submaximal running speeds, V02 at a lactate level of 3 mmoll '(V02-lac3) was determined both for the continuous and the interval treadmill test.
Field tests: Group A and six players of group B
performed an interval field test. The course for this test is shown in Fig. 4. The activity alternated between high- and lowintensity exercise for 15 and lOs, respectively. The duration of the test was 16.5 mm. Thus, total durations of high- and low-intensity exercise were 10 and 6.5 mm, respectively. During the high intensity periods the players followed the outlined route
with different locomotion forms (side-stepping, backwards and forward running). The low-intensity periods consisted of 10 s jogging to the centre and back to the stop-position. The test result was the distance covered during the 10 mm of high intensity exercise. Group A and the other six players of group B car-
ried out a continuous field test, which was a slight modification of a previously described procedure (8). The test result was the time required to cover four laps of a track (4 times 540 m). Before both the field tests the subjects warmed up for 15 mm, and immediately after the tests a finger tip blood sample for lactate analysis was taken.
Analysis Expiratory gas was collected in Douglas bags and the volume was measured with a Tissot spirometer. Oxygen (02) and carbon dioxide (C02) concentrations were deter-
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1
Comparison of Various Exercise Tests with Endurance Peiformance during Soccer
128 mt. J. Sports Med. 13 (1992)
J. Bangsbo, F. Lindquist
Table 2 Correlation coefficients for individual relationships between the measured variables Tests
Match-distances
Matchdistance
Intermittent endur. test distance
Field tests Interval Continuous Continuous
Enzymes
VO2max HAD CS
Interval
test distance
16 (8)
.70 (8)
.
lriterv. field test
.38 (14)
.23 (14)
.83*(8)
— .68(14)
—.44 (14)
—.57 (8)
— .78* (8)
VO2-lac301
.58*(20)
.26 (20)
.27 (8)
,69*(14)
— .49 (14)
V02-lac3
.60 (8)
.25 (8)
— .33 (8)
.07 (8)
.13 (8)
.32 (8)
•
•
.64(20)
.40 (20)
.18 (8)
.47 (14)
— .47 (14)
.78*(20)
.00 (8)
.42 (8)
.28 (8)
.06 (8)
— .67 (8)
— .57 (8) — .66 (8)
.
CS
— .63 (8)
—.40 (8)
—.32 (8)
(8)
.20 (8)
— .81* (8)
—.47 (8) — .84*(8)
.60 (8)
(8)
.34 (8)
.49 (8)
.27 (8)
.22 (8)
— .20 (8)
—.13 (8)
.42 (8) — .10 (8)
— .07 (8)
.27 (8)
.23 (8)
.29 (8)
— .23 (8)
— .56 (8)
— .46 (8) — .61 (8)
.21
— .30
.56 (8)
.16 (8)
.65 (8)
. .65 (8)
• .42 (8)
•
*Significant correlation between variables. (n): number of observations.
mined with paramagnetic 02 (Servomex) and infrared C02 (Beckman LB-Il) analysers, respectively. These analysers were regularly calibrated with known concentrations of gas determined by the Scholander technique. The blood samples were placed in ice-cold 0.6 M perchloric acid, centrifuged and the supernatants were frozen at —40 °C. They were analysed for lactate by enzymatic spectrophotometric methods (13).
Muscle biopsies: Muscle biopsies were dissected into two parts. One piece was frozen directly in liquid N2 and used for biochemical analyses. The remaining part was mounted in an embedding medium for histochemical analyses and frozen in isopentane cooled to freezing point. The samples were stored at — 80 °C until analyses were performed. Histochemical analyses: Serial transverse sections ((Im) were cut with a microtome at —20 °C and histochemically stained for myofibrillar ATPase activity (22). Fibre classification into ST, FTa, and FTh fibres was based on myofibrillar ATPase stains after preincubation at pH 4.3, 4.6, and 10.3 (5).
described by Essen-Gustavsson and Henriksson (9). Enzyme
activities were measured at 25 °C and expressed as
imolmin g dry weight. Statistics Standard procedures were used for regression and correlation analysis, and statistical tests were done using Student's t-test. Results
Match-distances The mean match-distance was 10.98 (range: 8.99— 12.65, n = 20) km, of which the high-intensity distance
accounted for 19% or 2.1 (0.6—3.8) km. The match-distance
was related to the high-intensity distance (r=0.6l, n=20, p 0.05) or to high-intensitydistance during a match (r=0.23, n= 14, p>0.05) (Fig. 8). The running time for the
Mean lactate concentrations after the interval and continuous field tests were 7.8 (5.1—12.7) and 11.0 (8.8—
13.6) mmoll respectively. Muscle characteristics
continuous field test averaged 10.44 (9.50—11.95) mm. An in-
The muscle CS and HAD averaged 78.6(65.9—
dividual, inverse relationship (r= —0.68, n= 14, p 0.05) nor the intermittent endurance test distance (r —0.57, n 8, p > 0.05) were correlated to the test result for the continuous field test (Fig. 9).
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km
130 mt. J. Sports Med. 13 (1992)
J. Bangsho, F. Lindquist km
high-intensity distance
high-intensity distance
4 krnf
3
3
2
2
1
r = 0.23
.______________
.
.
r=0.40
km
km 13
match-distance
13
0
5
match-distance
o
S
r=0.38
12
10
r = 0.64 9J
intermittent endurance test
km 18 17 16 15
intermittent endurance test
km V
18
TT 55
60
17
65
r = 0.83
16
0
r=0.18
a
V
15
70 ml kg1min1
0 1.7
0
1.8
\7O2max
1.9
2.0
2.1 km
interval field test
Fig. 7 Individual relationship between VO2max and distance covered during the intermittent endurance test (lower panel), match-distance (middle panel), and high-intensity distance (upper panel) (for def. see Methods).
Fig. 8 Individual relationship between distance covered during the interval field test and distance covered during the intermittent endurance test (lower panel), match-distance (middle panel), and highintensity-distance (upper panel) (for def. see Methods).
— Intermittent endurance
— Intermittent endurance
test distance (km) = \JO2max (ml min1 kg1)
test distance (km) =
interval test distance (km) x 12.2—5.9.
x 0.07+ 12.07.
— Match distance (km) = interval test distance (km) x 3.7+4.0.
— Match-distance (km) = 9O2max (ml min1 kg1) x 0.14+2.65.
— High-intensity-
distance (km) = — High-intensity
distance (km) =
interval test distance (km) x 1.53—0.52.
VO2max (ml min1 kg1) x 0.07 —2.25. since the physical performance during match is influenced by
the intermittent endurance test. CS was inversely correlated to VO2max (r = —0.84, n = 8, p < 0.05) and V02-lac3 for the continuous exercise test (r= —0.81, n 8, p < 0.05) (Table
several factors, e. g. tactical limitations or less than an optimal degree of motivation (3). However, only minor variations are observed in high-intensity distance from match to match, suggesting that it can be used as an indicator of this capacity (3). The high-intensity distance was best correlated to the distance of the prolonged, exhaustive intermittent exercise test (Table 2). The mode of exercise during this test was similar to the exercise pattern used in soccer and the players were accustomed to
2).
performing exhaustive exercise on the treadmill. Thus, the
with 4.67 (3.57—5.97), 4.73 (3.79—5.24) and 4.39 (2.86—5.20)
capillaries around the ST-, FTa-, and FTb-fibre, respectively.
None of these muscle variables were related to match-distance, high-intensity distance, or the distance covered during
Discussion
A single reliable measure of the physical ability
to perform long term, intermittent exercise during a soccer match (the soccer-specific endurance capacity) may not exist,
standardized intermittent endurance test distance might be the best objective measure of the potential physical soccer capacity obtained in the present study.
Increasing the carbohydrate intake above that found in the usual diet of the soccer players has been shown to
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11
Comparison of Various Exercise Tests with Endurance Perjbrmance during Soccer
The intermittent endurance test is time con-
high-intensity distance
km
mt. J. Sports Med. 13(1992) 131
suming and a treadmill is needed. Therefore, for practical pur-
4
D 3
r=0.44 2
.
km 13
linear relationship between the interval field test result and the
match-distance for the three match-players, and by the fact that, in relation to the obtained test result, none of the other players covered a longer match-distance than determined from the relationship among the three match-players (Fig. 8).
match-distance
0
.
12
poses a simple test was desirable. The relationship between performance in the endurance test and the interval field test performance suggests that the latter can be used as a measure of the intermittent endurance capacity and, perhaps, of the soccer-specific endurance capacity. This was supported by a
The usefulness of the interval field test is also supported by the
finding that the mean blood lactate concentration was 7 mmol F after the test. This concentration is of a similar magnitude to that found during the more intense part of soccer
r=0.68=0.68
10
matches (3, 7).
V
intermitlent endurance test km 18 17
0
15.
0
r = 0.57
A
9
10
11
12mm
time continuous field test
Fig. 9 Individual relationship between distance covered during the continuous field test and distance covered during the intermittent endurance test (lower panel), match-distance (middle panel), and high-intensity distance (upper panel) (for def. see Methods). — Intermittent endurance
test distance (kni) =
cont. field test (mm) x (—2.20) + 39.4.
— Match-distance (km) = cont. field test (mm) x (—0.89) + 20.1. — I-Ugh-intensity
distance (km) =
ous treadmill test, expressed as the V02 corresponding to 3 mmol F blood lactate, were correlated to match-distance. However, they were not related to the intermittent endurance performance, and no linear relationship was found between match-distance and V02-lac3 for the match-players (Fig. 7; 0, 0). Likewise, blood lactate concentrations determined during the interval treadmill test were not related to the intermittent endurance test distance. Thus, lactate measurements after continuous or interval submaximal treadmill running
,
+
16
The blood lactate concentration measured after submaximal exercise has been shown to be a good predictor of long term, continuous running performance (see 11, 16). In the present study lactate measurements during the continu-
9
cont. field test (mm) x (—0.57) + 8.0.
the intermittent exercise performance (4). However, the composition of the diet prior to the intermittent endurance
enhance
test in the present study was similar to the usual diet of the play-
ers (4), and they were instructed to maintain their normal diet throughout the study. Thus, the test results should not have been influenced by the diet.
The distance covered during the intermittent endurance test was not correlated to the match-distance. Three of the players (Fig. 5; 0, , D) differed from the remaining five by having a markedly longer match-distance relative to their performance during the prolonged, intermittent test. Apparently only these players were close to their potential maxi-
mal distance during the observed matches. These are called "match-players" in the following discussion.
seem not to be sensitive measures of either the intermittent endurance performance or physical performance during a soccer
match. This conclusion is the same when using any of these data for the blood lactate responses to submaximal continuous or interval running. The blood lactate concentration, and the relative utilization of fat and carbohydrate during submaximal continuous exercise has been associated with the activity of muscle mitochondrial enzymes (17, 19). The magnitude of muscle enzyme activities representing tricarboxylic acid cycle and n-oxidation for the elite soccer players in the present study was similar to values found for endurance-trained athletes and was significantly higher than found in earlier studies of semiprofessional soccer players (2, 18, 20). The variations in the activities of these muscle enzymes within the group were small, and they were not related to the differences in intermittent ex-
ercise performance and blood lactate concentrations during submaximal running. Similarly the muscle morphological data could not explain the difference in performance. Thus, in this group of well-trained athletes, muscle characteristics do not give indices of intermittent endurance performance. As found in other studies (24, 25, 26), a relationship between VO2max and distance covered during the match was established. However, VO2max was not correlated to the distance covered during the intermittent endurance test, and no linear relationship between VO2max and match-distance was found for the match-players (Fig. 7; 0, , El). Thus, VO2max does not seem to be an accurate measure of the soccer-specific endurance capacity. This is in agreement with earlier findings in soccer and other sports (2, 6, 27). Thus, in stu-
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11
mt. J. Sports Med. 13 (1992)
dies of endurance-trained cyclists with similar maximum oxygen uptakes, a great variation in endurance capacity for continuous exercise was observed (6).
In summary, based on the relationship between the distance covered during the intermittent endurance test and the interval field test distance, it seems that the latter can be used to evaluate long term, intermittent exercise performance and, perhaps, the soccer-specific endurance capaci-
ty. The lack of a correlation between the distance covered during the prolonged, intermittent test and performance during a match suggests that all players did not fully utilize this
capacity during the match. Muscle characteristics, VO2max and blood lactate seem not to be sensitive measures of physical performance in soccer. Acknowledgement The study was made possible by grants from Team Danmark and Idruttens Forskningsrâd.
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.Jens Bangsbo
August Krogh Institute Universitetsparken 1 3 DK-2100 Copenhagen 0 Denmark
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