Perceptual and Motor Skillr, 1992, 75, 1075-1082.
O Perceptual and Motor Skills 1992
REACTION TIMES WITH REFERENCE TO MUSCULOSKELETAL COMPLAINTS I N ADOLESCENCE SIMO TAIMELA AND U R H O M. KUJALA Helsinki Research Institute for Sports and Exercise Medicine Summary.-Recent studies have related long reaction times and various musculoskeletal complaints in different groups of adults. The aim here was to analyze reaction times with reference to musculoskeletal complaints in adolescent athletes and controls. Simple reaction time and choice reaction time were measured, and inquiries made about various musculoskeletal injuries of 119 subjects aged 1 1 to 14 years. Gender, age, maturational age, body composition, and participation in sports were included in the analyses as subject-related factors affecting reaction times. Prolonged simple reaction time was related to low-back and lower extremity complaints in a two-way analysis of variance. The finding agreed with data of previous studies suggesting that slow psychomotor speed of reaction is associated with the outcome of musculoskeletal injuries.
Reaction time, i.e., the time from the onset of an unexpected stimulus to the initiation of the response, has been recognized as a means of relating simple mental events to physical measures since the nineteenth century. Reaction time (RT) measures are common in research for two main reasons. First, reaction times are components of real-life tasks, e.g., in sports and traffic. Second, RTs measure the time taken for mental events, such as stimulus processing, decision making, and response programming (Marteniuk, 1976; Matthews & Dorn, 1989; Schmidt, 1988). Conventional methods in the measurement of RTs are apparatus tests which involve motor response to visual stimuli. Simple reaction time in which there is only one signal and corresponding response is often distinguished from choice reaction time. I n choice RT, there are several signals and corresponding responses. Musculoskeletal injuries are a major health problem. These injuries result from a complex interaction of multiple risk factors combined with a situation that could result in an injury. An effective prevention of injury includes recognition of potential injury risk factors at an early stage. Attention has recently been paid to intrinsic, i.e., individual-related injury risk factors in sports (Backx, Beijer, Bol, & Erich, 1991; Kujala, 1986; Lysens, Ostyn, van den Auweele, Lefevre, Vuylsteke, & Renson, 1989; Taimela, Kujala, & dsterman, 1990). The individual characteristics recognized as injury risk factors include anatomical and biomechanical factors (Kujala, 1986), poor aerobic or muscle fitness (Kerr & Minden, 1988; Watson, 1984), former injuries (Ekstrand & Gillquist, 1983; Lysens, Stevernl~nck,van den Au'The study was financially supported by the Finnish Ministry of Education. 'Address correspondence to Simo Taimela, Helsinki Research Institute for Sports and Exercise Medicine, Mannerheimintie 17, Toolon kisahalli, SF-00250 Helsinki, Finland.
1076
S. TAIMELA
&
U. M. KUJALA
weele, Lefevre, Renson, Cleassens, & Ostyn, 1984; Robey, Blyth, & Mueller, 1971), psychological factors (Jackson, Jarrett, Bailey, Kausek, Swanson, & Powell, 1978; Taerk, 1977; Valliant, 1981), and accumulation of life stress (Bramwell, Masuda, Wagner, & Holmes, 1975; Coddington & Troxell, 1980; Cryan & Alles, 1983; Kerr & Minden, 1988; Passer & Seese, 1983). Also, long RTs have been connected to an increased prevalence of musculoskeletal injuries recently. Low grade inteUigence (IQ) and slow choice R T were related to history of accidental bone fracture in young men (Taimela, 1990; Tairnela, Kujala, & ~ s t e r m a n ,1991). The study group included a cohort of 123 army conscripts who were interviewed for previous accidents, and I Q and choice R T were tested. Long simple R T was associated with injuries in soccer (Taimela, ~ s t e r m a n ,Kujala, Lehto, Korhonen, & Alaranta, 1990). Subjects with chronic low-back pain were slower on a choice RT test than controls in a preliminary study (Taimela, Osterman, Alaranta, Soukka, & Kujala, 1992). However, these study groups focusing on the RT-injury relationship included adults only. The present study was designed to identify the relationships between reaction times and musculoskeletal complaints in a sample of adolescent athletes and their corresponding controls. The two most frequent musculoskeletal complaints in adolescent athletes concern lower extremities and low-back (Kujala, Salrninen, Taimela, Oksanen, & Jaakkola, 1992), so the injury criteria included lower extremity and low-back complaints. Several factors affect reaction time testing (Brebner & Welford, 1980; Rabbitt & Banerji, 1989; Schmidt, 1988; Taimela, 1991; Welford, 1980a); the effects of gender, age, maturational age, body composition, and participation in sports on RTs were analyzed in this study as possible confounding factors.
METHOD
Subjects The study population included 86 athletes and 33 nonathletes, altogether 119 subjects (52 boys and 67 girls) in the age range of 11.3 to 14.3 yr. Informed written consent was obtained from each subject and from a parent or guardian prior to the data collection. The athletes (n = 86) had a mean age of 13 years and had regularly practiced for three years at the minimum, at least twice a week under the auspices of a coach in different specific sports clubs. The nonathletes (n = 33, 16 boys and 17 girls) were pupils of the same age from two public schools and participated only sporadically, less often than twice a week, in recreational sports. The athletic boys were involved in club level soccer (n = 19) or ice hockey (n = 17) and the athletic girls in gymnastics (n = 141, skating (n = 171, or ballet (n = 19). The number of subjects in the control groups was selected to correspond to the number of subjects in each of the study groups.
RT AND MUSCULOSKELETAL COMPLAINTS
1077
Measurements A questionnaire was given subjects by the study assistant or club trainer, and the subjects answered the inquiry at home. When the subjects came into the testing laboratory, the study assistant ensured that the questionnaire was properly answered. The inquiry included questions on physical activity history, and a questionnaire developed earlier (Salminen, Pentti, & Terho, 1992) was used to document different pain symptoms interfering with schoolwork or leisure time during the past 12 months and continuous or recurrent back pain. To minimize the classification problems, the lower back pain was defined exactly in relation to time, and the localization of low-back area was illustrated by drawing. Then the subjects underwent a clinical examination by a physician. The injury criteria included lower extremity pains and lowback complaints interfering with training. Height measurements to the nearest 0.5 cm and weight measurements to the nearest 0.5 kg were recorded and body mass index (BMI = weight x heighr2) was calculated. Body fat percentage was calculated on the basis of four skinfolds according to the nomogram for children (Durnin & Rahaman, 1967). Tanner's stages of maturity (Tanner, 1975) were self-assessed by the subject according to the method of Morris and Udry (1780). This self-assessment included separate drawing-series illustrating five stages of the development of (1) male genitalia, (2) male pubic hair, (3) female breasts, and (4) female pubic hair. Instructions request the adolescent to "choose the drawing closest to your stage of development." Written descriptions amplify the drawings. The subjects' simple reaction time and choice reaction time were tested. The task in the simple R T test was to press a button in response to a red light-stimulus as fast as possible. The index finger of the preferred hand was held ready on the button at the beginning of each trial. No warning signal preceded the stimulus, and the intertrial interval varied from one to four seconds at random. Catch trials for longer than IOOO msec. were excluded. Response times were recorded and the mean of five trials was calculated. On the choice R T test there were four lights, white, green, red, and blue for stimuli and the corresponding buttons for responses on the subject's panel of the apparatus (Model 63035, Lafayette, Inc., Lafayette, Indiana, USA). The subject pressed the buttons in response to the stimuli. The next stimulus was given only if the subject had reacted correctly to the previous one. Response times were recorded and the mean of eight trials was calculated. Neither simple RT nor choice RT was fractionated into decision and movement times. The R T tests were supervised by one examiner who always followed the text protocol described above. The content of the instruction was the same across the tests, and the number of training sessions given to subjects was standardized in both of the tests in order to minimize the learning effect. Subjects with a defect in color vision were excluded from the tests.
1078
S. TAIMELA & U. M. KUJALA
Statistics The statistical analyses were computed by using appropriate procedures from SASISTAT (SAS Institute, Inc., Cary, North Carolina) program library. Testing of factors affecting reaction time was performed using proc glm which handles classification variables; simple R T and choice R T were in equation to gender, age, maturational age, body composition, and participation in sports in a multivariate regression model. As gender had a significant effect on RT, further analyses included a two-way analysis of variance (proc glm) which handles unbalanced classification variables. Lower extremity and low-back complaints during the year preceding the tests were analyzed with reference to simple and choice RTs and gender. As both gender and R T had significant effects on lower extremity pain, association between two dichotomous variables, gender and lower extremity pain, were analyzed with the chi-squared test.
RESULTSAND DISCUSSION Gender had a significant effect on simple RT ( p = 0.004) in the over-all multivariate analysis (F,,,,, = 2.80, p = 0.005) where simple RT was associated with gender, age, maturational age, body composition, and participation in sports. Mean R T (SD)was 237 msec. (27) for boys and 260 msec. (33) for girls at the same age. Longer RTs for women than for men have been reported among adults in previous studies also (Giambra & Quilter, 1989; Welford, 1980b). Correspondingly, mean choice RT was 478 msec. (57) for boys and 502 msec. (56) for girls ( p = 0.02). Body composition variables, age, and maturational age had no significant effects on RTs, which agrees with a previous study also (Taimela, 1991). However, the age variation was small in our study, i.e., wider age groups need to be tested before far-reaching conclusions can be made. Generally, speed of reaction increases up to early adulthood and then decreases with all levels of test complexity (Era, Jokela, & Heikkinen, 1986; Hodgkins, 1963; Welford, 1980b). RTs did not vary with participation in sports even though some researchers have reported differences in reaction times between athletes and nonathletes and among different levels of activity within athletes (Christenson & Winkelstein, 1988; Harbin, Durst, & Harbin, 1989; Mero, Jaakkola, & Komi, 1989; Taimela, bsterman, Kujala, Lehto, Korhonen, & Alaranta, 1990). However, we did not evaluate other hobbies such as videogame playing that may affect RTs. No correlation was found between the weekly time spent at sports exercise and simple RT (r = 0.16) or choice R T (r = 0.24), so gender only was included as a covariate in the further analyses. Complaints of lower extremities involved predominantly boys: 22 complaints were reported by 52 boys and 17 complaints by 67 girls ( X 2 = 3.8, p = 0.05). Boys had shorter RTs than girls on average; prolonged simple RT was significantly related ( p = 0.01) to lower limb pain when gender was in-
TABLE 1 NONADJUSTED MFANSAND STANDARD DEVIATIONS FOR GROUPSBASEDON OCCURRENCE OF BACKCOMPLAINTS A N D LIMBPAINS* Measure
N o Complaints, n: 75
M
SD
Low-back Complaint Only, n: 5
M
SD
Boys 12.9 0.3 12.7 0.2 Girls 12.7 0.7 13.3 0.2 Height, cm Boys 157.0 9.0 151.0 2.0 Girls 156.0 8.0 158.0 3.0 We~ght,kg Boys 45.7 8.5 40.1 2.1 Girls 44.5 8.6 47.6 4.5 Fat, % Boys 15.0 4.7 15.8 8.8 Girls 19.8 5.4 18.8 2.6 Body Mass Index Boys 18.3 2.2 17.7 0.5 Girls 18.2 2.4 19.0 1.1 Simple RT, msec. Boys 232 28 250 36 Girls 255 27 257 26 Choice RT, msec. Boys 479 55 5 16 86 Girls 498 56 546 97 *The subjects with both back and limb complaints have been combined; the analyses were done Age, yr.
Lower Limb Pain Only, n: 35
M 12.8 13.1 156.0 156.0 45.1 44.2 14.3 18.9 18.6 18.1 242 267 476 503
SD 0.3 0.7 6.0 8.0 5.9 7.7 5.5 5.3 2.3 2.3 26 31 58 49
Back Complaint + Limb Pain, n: 4
M 12.9 12.0 155.0 155.0 41.6 46.1 12.5 19.0 17.2 19.0 250 341 435 512
for both the injury groups separately.
SD 0.2 0.9 8.0 8.0 9.3 5.9 0.0 0.0 2.1 0.4 4 87 55 65
F +I
5
U
E
C
?c
s
3
z
9 r'
8 5 l-
zz
4
Cn
S. TAIMELA & U. M. KUJALA
1080
cluded in the two-way analysis of variance (F,,,,, = 5.2, p = 0.006). Group means are shown in Table 1. I n a previous study, long simple R T was associated with injuries in soccer (Taimela, ~ s t e r r n a n ,Kujala, Lehto, Korhonen, & Alaranta, 1990); the study sample included young male elite athletes and the soccer injuries involved predominantly lower extremities. Prolonged simple R T tended to be longer (p = 0.02) in subjects with low-back-pain complaints interfering with training when gender was included in the two-way analysis of variance (F,,,,, = 2.8, p = 0.06). Back complaints occurred equally in both genders; 4 complaints were reported by boys and 5 complaints by girls. Reaction time group means are shown in Table 1. Long RTs have earlier been reported in association with accidental musculoskeletal injuries (Taimela, 1990; Taimela, Kujala, & Osterman, 1771) or with chronic low-back pain (Taimela, et al., 1992). However, choice R T was not significantly associated to musculoskeletal complaints in this study but to simple RT only. We have no definite interpretation for this effect; however, the study material was small and the different choice R T recording equipment may have had some impact on the results also. TABLE 2 SUMMARY OF ANALYSESOF VARIANCE: F RATIOSAND ps
Variables Dependent Back
BY
VARIABLE
Model
P
Independent
Pain Gender
O Perceptual and Motor Skills 1992
REACTION TIMES WITH REFERENCE TO MUSCULOSKELETAL COMPLAINTS I N ADOLESCENCE SIMO TAIMELA AND U R H O M. KUJALA Helsinki Research Institute for Sports and Exercise Medicine Summary.-Recent studies have related long reaction times and various musculoskeletal complaints in different groups of adults. The aim here was to analyze reaction times with reference to musculoskeletal complaints in adolescent athletes and controls. Simple reaction time and choice reaction time were measured, and inquiries made about various musculoskeletal injuries of 119 subjects aged 1 1 to 14 years. Gender, age, maturational age, body composition, and participation in sports were included in the analyses as subject-related factors affecting reaction times. Prolonged simple reaction time was related to low-back and lower extremity complaints in a two-way analysis of variance. The finding agreed with data of previous studies suggesting that slow psychomotor speed of reaction is associated with the outcome of musculoskeletal injuries.
Reaction time, i.e., the time from the onset of an unexpected stimulus to the initiation of the response, has been recognized as a means of relating simple mental events to physical measures since the nineteenth century. Reaction time (RT) measures are common in research for two main reasons. First, reaction times are components of real-life tasks, e.g., in sports and traffic. Second, RTs measure the time taken for mental events, such as stimulus processing, decision making, and response programming (Marteniuk, 1976; Matthews & Dorn, 1989; Schmidt, 1988). Conventional methods in the measurement of RTs are apparatus tests which involve motor response to visual stimuli. Simple reaction time in which there is only one signal and corresponding response is often distinguished from choice reaction time. I n choice RT, there are several signals and corresponding responses. Musculoskeletal injuries are a major health problem. These injuries result from a complex interaction of multiple risk factors combined with a situation that could result in an injury. An effective prevention of injury includes recognition of potential injury risk factors at an early stage. Attention has recently been paid to intrinsic, i.e., individual-related injury risk factors in sports (Backx, Beijer, Bol, & Erich, 1991; Kujala, 1986; Lysens, Ostyn, van den Auweele, Lefevre, Vuylsteke, & Renson, 1989; Taimela, Kujala, & dsterman, 1990). The individual characteristics recognized as injury risk factors include anatomical and biomechanical factors (Kujala, 1986), poor aerobic or muscle fitness (Kerr & Minden, 1988; Watson, 1984), former injuries (Ekstrand & Gillquist, 1983; Lysens, Stevernl~nck,van den Au'The study was financially supported by the Finnish Ministry of Education. 'Address correspondence to Simo Taimela, Helsinki Research Institute for Sports and Exercise Medicine, Mannerheimintie 17, Toolon kisahalli, SF-00250 Helsinki, Finland.
1076
S. TAIMELA
&
U. M. KUJALA
weele, Lefevre, Renson, Cleassens, & Ostyn, 1984; Robey, Blyth, & Mueller, 1971), psychological factors (Jackson, Jarrett, Bailey, Kausek, Swanson, & Powell, 1978; Taerk, 1977; Valliant, 1981), and accumulation of life stress (Bramwell, Masuda, Wagner, & Holmes, 1975; Coddington & Troxell, 1980; Cryan & Alles, 1983; Kerr & Minden, 1988; Passer & Seese, 1983). Also, long RTs have been connected to an increased prevalence of musculoskeletal injuries recently. Low grade inteUigence (IQ) and slow choice R T were related to history of accidental bone fracture in young men (Taimela, 1990; Tairnela, Kujala, & ~ s t e r m a n ,1991). The study group included a cohort of 123 army conscripts who were interviewed for previous accidents, and I Q and choice R T were tested. Long simple R T was associated with injuries in soccer (Taimela, ~ s t e r m a n ,Kujala, Lehto, Korhonen, & Alaranta, 1990). Subjects with chronic low-back pain were slower on a choice RT test than controls in a preliminary study (Taimela, Osterman, Alaranta, Soukka, & Kujala, 1992). However, these study groups focusing on the RT-injury relationship included adults only. The present study was designed to identify the relationships between reaction times and musculoskeletal complaints in a sample of adolescent athletes and their corresponding controls. The two most frequent musculoskeletal complaints in adolescent athletes concern lower extremities and low-back (Kujala, Salrninen, Taimela, Oksanen, & Jaakkola, 1992), so the injury criteria included lower extremity and low-back complaints. Several factors affect reaction time testing (Brebner & Welford, 1980; Rabbitt & Banerji, 1989; Schmidt, 1988; Taimela, 1991; Welford, 1980a); the effects of gender, age, maturational age, body composition, and participation in sports on RTs were analyzed in this study as possible confounding factors.
METHOD
Subjects The study population included 86 athletes and 33 nonathletes, altogether 119 subjects (52 boys and 67 girls) in the age range of 11.3 to 14.3 yr. Informed written consent was obtained from each subject and from a parent or guardian prior to the data collection. The athletes (n = 86) had a mean age of 13 years and had regularly practiced for three years at the minimum, at least twice a week under the auspices of a coach in different specific sports clubs. The nonathletes (n = 33, 16 boys and 17 girls) were pupils of the same age from two public schools and participated only sporadically, less often than twice a week, in recreational sports. The athletic boys were involved in club level soccer (n = 19) or ice hockey (n = 17) and the athletic girls in gymnastics (n = 141, skating (n = 171, or ballet (n = 19). The number of subjects in the control groups was selected to correspond to the number of subjects in each of the study groups.
RT AND MUSCULOSKELETAL COMPLAINTS
1077
Measurements A questionnaire was given subjects by the study assistant or club trainer, and the subjects answered the inquiry at home. When the subjects came into the testing laboratory, the study assistant ensured that the questionnaire was properly answered. The inquiry included questions on physical activity history, and a questionnaire developed earlier (Salminen, Pentti, & Terho, 1992) was used to document different pain symptoms interfering with schoolwork or leisure time during the past 12 months and continuous or recurrent back pain. To minimize the classification problems, the lower back pain was defined exactly in relation to time, and the localization of low-back area was illustrated by drawing. Then the subjects underwent a clinical examination by a physician. The injury criteria included lower extremity pains and lowback complaints interfering with training. Height measurements to the nearest 0.5 cm and weight measurements to the nearest 0.5 kg were recorded and body mass index (BMI = weight x heighr2) was calculated. Body fat percentage was calculated on the basis of four skinfolds according to the nomogram for children (Durnin & Rahaman, 1967). Tanner's stages of maturity (Tanner, 1975) were self-assessed by the subject according to the method of Morris and Udry (1780). This self-assessment included separate drawing-series illustrating five stages of the development of (1) male genitalia, (2) male pubic hair, (3) female breasts, and (4) female pubic hair. Instructions request the adolescent to "choose the drawing closest to your stage of development." Written descriptions amplify the drawings. The subjects' simple reaction time and choice reaction time were tested. The task in the simple R T test was to press a button in response to a red light-stimulus as fast as possible. The index finger of the preferred hand was held ready on the button at the beginning of each trial. No warning signal preceded the stimulus, and the intertrial interval varied from one to four seconds at random. Catch trials for longer than IOOO msec. were excluded. Response times were recorded and the mean of five trials was calculated. On the choice R T test there were four lights, white, green, red, and blue for stimuli and the corresponding buttons for responses on the subject's panel of the apparatus (Model 63035, Lafayette, Inc., Lafayette, Indiana, USA). The subject pressed the buttons in response to the stimuli. The next stimulus was given only if the subject had reacted correctly to the previous one. Response times were recorded and the mean of eight trials was calculated. Neither simple RT nor choice RT was fractionated into decision and movement times. The R T tests were supervised by one examiner who always followed the text protocol described above. The content of the instruction was the same across the tests, and the number of training sessions given to subjects was standardized in both of the tests in order to minimize the learning effect. Subjects with a defect in color vision were excluded from the tests.
1078
S. TAIMELA & U. M. KUJALA
Statistics The statistical analyses were computed by using appropriate procedures from SASISTAT (SAS Institute, Inc., Cary, North Carolina) program library. Testing of factors affecting reaction time was performed using proc glm which handles classification variables; simple R T and choice R T were in equation to gender, age, maturational age, body composition, and participation in sports in a multivariate regression model. As gender had a significant effect on RT, further analyses included a two-way analysis of variance (proc glm) which handles unbalanced classification variables. Lower extremity and low-back complaints during the year preceding the tests were analyzed with reference to simple and choice RTs and gender. As both gender and R T had significant effects on lower extremity pain, association between two dichotomous variables, gender and lower extremity pain, were analyzed with the chi-squared test.
RESULTSAND DISCUSSION Gender had a significant effect on simple RT ( p = 0.004) in the over-all multivariate analysis (F,,,,, = 2.80, p = 0.005) where simple RT was associated with gender, age, maturational age, body composition, and participation in sports. Mean R T (SD)was 237 msec. (27) for boys and 260 msec. (33) for girls at the same age. Longer RTs for women than for men have been reported among adults in previous studies also (Giambra & Quilter, 1989; Welford, 1980b). Correspondingly, mean choice RT was 478 msec. (57) for boys and 502 msec. (56) for girls ( p = 0.02). Body composition variables, age, and maturational age had no significant effects on RTs, which agrees with a previous study also (Taimela, 1991). However, the age variation was small in our study, i.e., wider age groups need to be tested before far-reaching conclusions can be made. Generally, speed of reaction increases up to early adulthood and then decreases with all levels of test complexity (Era, Jokela, & Heikkinen, 1986; Hodgkins, 1963; Welford, 1980b). RTs did not vary with participation in sports even though some researchers have reported differences in reaction times between athletes and nonathletes and among different levels of activity within athletes (Christenson & Winkelstein, 1988; Harbin, Durst, & Harbin, 1989; Mero, Jaakkola, & Komi, 1989; Taimela, bsterman, Kujala, Lehto, Korhonen, & Alaranta, 1990). However, we did not evaluate other hobbies such as videogame playing that may affect RTs. No correlation was found between the weekly time spent at sports exercise and simple RT (r = 0.16) or choice R T (r = 0.24), so gender only was included as a covariate in the further analyses. Complaints of lower extremities involved predominantly boys: 22 complaints were reported by 52 boys and 17 complaints by 67 girls ( X 2 = 3.8, p = 0.05). Boys had shorter RTs than girls on average; prolonged simple RT was significantly related ( p = 0.01) to lower limb pain when gender was in-
TABLE 1 NONADJUSTED MFANSAND STANDARD DEVIATIONS FOR GROUPSBASEDON OCCURRENCE OF BACKCOMPLAINTS A N D LIMBPAINS* Measure
N o Complaints, n: 75
M
SD
Low-back Complaint Only, n: 5
M
SD
Boys 12.9 0.3 12.7 0.2 Girls 12.7 0.7 13.3 0.2 Height, cm Boys 157.0 9.0 151.0 2.0 Girls 156.0 8.0 158.0 3.0 We~ght,kg Boys 45.7 8.5 40.1 2.1 Girls 44.5 8.6 47.6 4.5 Fat, % Boys 15.0 4.7 15.8 8.8 Girls 19.8 5.4 18.8 2.6 Body Mass Index Boys 18.3 2.2 17.7 0.5 Girls 18.2 2.4 19.0 1.1 Simple RT, msec. Boys 232 28 250 36 Girls 255 27 257 26 Choice RT, msec. Boys 479 55 5 16 86 Girls 498 56 546 97 *The subjects with both back and limb complaints have been combined; the analyses were done Age, yr.
Lower Limb Pain Only, n: 35
M 12.8 13.1 156.0 156.0 45.1 44.2 14.3 18.9 18.6 18.1 242 267 476 503
SD 0.3 0.7 6.0 8.0 5.9 7.7 5.5 5.3 2.3 2.3 26 31 58 49
Back Complaint + Limb Pain, n: 4
M 12.9 12.0 155.0 155.0 41.6 46.1 12.5 19.0 17.2 19.0 250 341 435 512
for both the injury groups separately.
SD 0.2 0.9 8.0 8.0 9.3 5.9 0.0 0.0 2.1 0.4 4 87 55 65
F +I
5
U
E
C
?c
s
3
z
9 r'
8 5 l-
zz
4
Cn
S. TAIMELA & U. M. KUJALA
1080
cluded in the two-way analysis of variance (F,,,,, = 5.2, p = 0.006). Group means are shown in Table 1. I n a previous study, long simple R T was associated with injuries in soccer (Taimela, ~ s t e r r n a n ,Kujala, Lehto, Korhonen, & Alaranta, 1990); the study sample included young male elite athletes and the soccer injuries involved predominantly lower extremities. Prolonged simple R T tended to be longer (p = 0.02) in subjects with low-back-pain complaints interfering with training when gender was included in the two-way analysis of variance (F,,,,, = 2.8, p = 0.06). Back complaints occurred equally in both genders; 4 complaints were reported by boys and 5 complaints by girls. Reaction time group means are shown in Table 1. Long RTs have earlier been reported in association with accidental musculoskeletal injuries (Taimela, 1990; Taimela, Kujala, & Osterman, 1771) or with chronic low-back pain (Taimela, et al., 1992). However, choice R T was not significantly associated to musculoskeletal complaints in this study but to simple RT only. We have no definite interpretation for this effect; however, the study material was small and the different choice R T recording equipment may have had some impact on the results also. TABLE 2 SUMMARY OF ANALYSESOF VARIANCE: F RATIOSAND ps
Variables Dependent Back
BY
VARIABLE
Model
P
Independent
Pain Gender
