Agility is an important element of physical fitness that is required in many competitive sports, and it is a very complex concept (16). It has been understood simply as the speed of direction change (2). Agility is generally divided into reactive movements, which move the body quickly, and repeated movements, which move them quickly and repeatedly. Sakamaki et al. (12) gave reaction time from stimulus to starting movement, movement speed, and exchange speed between movements as factors determining superior-inferior agility. In this way, agility is often considered to consist of not only speed of direction change but also reaction speed to stimulus (14).
Side step (12), 505 (2), and zigzag running (13) tests are traditional agility tests and focus mostly on “quick body movement” and preprogrammed measured movements. The above tests may effectively assess the agility of athletes of closed skill sports but not those of open skill sports. Closed skill sports require agility for repeated predetermined or programmed movements, whereas open skill sports require adaptations to quickly changing situations, hurried judgments, and adequate responses. To adequately assess the agility of athletes majoring in open skill sports, it is important to evaluate “quick body movements” and “stimulus reaction speed,” and to require unplanned reaction movements.
Agility tests meet the above conditions. There are 2 test types: reactive agility test (1) and whole-body choice reaction test (17). Both tests require moving quickly toward an indicated direction, and thus, they can assess the speed that takes an adequate action to an unknown stimulus. However, these tests require reactions from a static state, in which subjects have enough time to predict the stimulus direction. In short, it may not always be an adequate test assessing the agility necessary to cope with changing situations. To adequately assess the agility of basketball and soccer players, a new test must be developed, one that requires that subjects react from a dynamic state (not a static state), and that contains successive stimuli (instead of a temporary stimulus).
Based on the above points, we attempted to develop a new “successive choice reaction test” that offers a direction indicator successively. This test requires quick reactions from a dynamic state and repeated movements to an unknown successive stimulus. In short, quick body movements and stimulus reaction speed are evaluated. If practical use of this test is possible, the agility of athletes majoring in open skill sports can be adequately assessed. In addition, the discovery of talented athletes is possible through adequate agility assessment. However, some issues exist for the practical use of this test.
One issue is setting a proper stimulus presentation tempo. In a successive choice reaction test, subjects are required to quickly respond to the successive stimuli. In this case, if a stimulus tempo is too fast, the subject cannot perform the test. If it is too slow, however, the test loses the characteristics of a successive stimulus presentation. Even if a set tempo is adequate, the test difficulty changes according to selected tempos and varied measurement values. Another issue is the test's reliability. If a test's reliability is low, it has little practical value. The measured values of the reaction times, in particular, are largely varied, and thus many trials are required. Because of the successive stimuli, this test may have larger variations of measurement than general reaction time tests. Therefore, its reliability should be tested.
Because it presents successive stimuli, this test requires subjects to react to a stimulus while trying to maintain a stable posture. In the case of a shorter tempo, there is little time to stabilize posture. Hence, it is believed that the reaction time to the next stimulus is delayed and that the variation of measurement increases. Therefore, it was hypothesized that tests with a shorter tempo are unreliable. This study aimed to examine adequate stimulus tempos and the reliability of a newly developed successive choice reaction test.
Experimental Approach to the Problem
We developed a successive choice reaction time test to assess the agility of open skill sports athletes. It is considered that this test is influenced by the stimulus presentation method and tempo, because it is necessary to present successive stimuli. Hence, it is important to examine these factors. This study employs a stimulus presentation that eliminates memory effect by using 5 stimulus presentation patterns and sets some stimulus presentation tempos based upon the reaction time of the choice reaction test. The tempo was an independent variable and the successive choice reaction time was a dependent variable. To examine its reliability, the test was repeated on another day.
The subjects were 15 university students majoring in sports, and with an athletic career of over 3 years (age: 20.4 ± 1.1 years, height: 174.5 ± 5.5 cm, weight: 66.9 ± 6.5 kg). They consisted of 4 basketball players, 4 soccer players, 3 baseball players, 1 badminton player, 1 rugby player, 1 runner, and 1 karate competitor. They trained in their respective sports 3–5 times per week. This study was conducted from September to December. The risks of this study were explained to all the subjects, each of whom gave written consent.
Overview of Test
Test device: Nine step seats (Walk-Way ver 1.11, Anima, Japan) and a laptop computer (FMV-BIBLO MG55R, Fujitsu, Japan) were used as the successive choice reaction test devices in this study. The former can record when the subject's feet touched the ground and sends it to the laptop as a digital signal. Nine 30-cm square seats were set (Figure 1). The distance from the center of the middle seat to the centers of the surrounding seats was 60 cm. Nine frames corresponding to the step seat array are displayed on the laptop (Figure 2). The center frame (sell), upper frame (sell), and downward frame (sell) on the display correspond to the middle seat, higher seat, and lower seat on the floor, respectively. The laptop is a stimulus presentation device, and a moving stimulus (movement direction frame color tuned from white to black) was successively displayed with a constant tempo.
Stimulus presentation pattern: To assess open skilled factors, stimulus directions must be set so that the subjects cannot predict them. If the stimulus presentation pattern is the same among trials, the subjects might remember the reaction directions. Thus, we made up 5 stimulus presentation patterns in advance and used them randomly.
Figure 1 shows the arrangement of the step sheets. According to each stimulus presentation pattern, the subjects moved to each cell. It was very difficult for them to predict reaction directions in advance, because of the different stimulus patterns in every trial. Each pattern consists of a combination of 8 directions (front, back, right, left, right front oblique, right back oblique, left front oblique, and left back oblique). The subjects must always move to another cell, under the condition that they step on all the cells at once.
Table 1 shows the 5 patterns used this study. For instance, in a case of pattern A, the subjects move in the following order: center cell, diagonal forward right cell, right cell, forward cell, diagonal left forward cell, center cell, right cell, backward cell, and center cell (Figure 2).
Stimulus presentation tempo: To assess agility by a successive choice reaction test, the subjects must achieve a stimulus tempo as soon as possible. To examine adequate tempo, as a pilot study, a whole-body choice reaction test was conducted using 10 typical male students (age: 20.1 ± 1.2 years, height: 172.5 ± 4.9 cm, weight: 63.9 ± 5.2 kg).
When presenting a reaction direction, the subjects stepped to the given cell as quickly as possible from a static state. Eight stimulus directions and 5 trials in each direction totaled 40 trials.
The stimulus direction order was random, so that subjects could not predict them. Of 5 trials, 3 trials excluding maximum and minimum values for the 8 directions were selected and their mean (24 trials) was calculated. From the results of this pilot test (shown in Table 2), which required that subjects step without delaying the next stimulus, it was judged that tempo of 1.3 seconds was required (mean landing time of both feet + 3SD = 1.23 seconds). Hence, we selected tempos of 1.3, 1.5, and 2.0 seconds.
The subjects were instructed to have sufficient sleep the night before and to have breakfast as usual on the day of the experiment. Before the test, the subjects' good physical condition was confirmed. To exclude interference from these conditions, the subjects repeated the test on another day. The subjects lightly bent both knees on the center cell of the step sheet, put their weight equally on both legs, stood with feet at shoulder width, and carefully watched the laptop display. The movie presenting the reaction direction was successively projected on the display. The subjects stepped quickly as cells were presented. The measurement order of every stimulus pattern and tempo was random. The subjects sufficiently practiced the test movement before measurement was taken. One trial test was performed for each pattern and tempo, respectively. To examine reliability, each subject repeated the test at the same time in the day within a week, considering subject's physical burden. Each test was conducted in the day, between 9 AM and 6 PM.
The evaluation variable was the successive choice reaction time. Table 3 shows the calculation method. A difference between the time at which stimulus is presented and the time in which the subject's 2 feet took off from step sheet was calculated in each stimulus presentation, and a mean of the 8 trials was calculated for each pattern. The above means were summed for 5 patterns and the mean was used as an evaluation parameter.
To examine the influence of tempo on the successive choice reaction test, the mean difference among the tempos was examined by 1-way analysis of variance (ANOVA), and the relationship among them was examined by Pearson's correlation coefficient. In addition, to examine reliability of this test, the day-to-day intraclass correlation coefficient (ICC) was calculated. The significant level was set at p ≤ 0.05
Table 4 shows the ICC of a successive choice reaction test. Every tempo test (1.3, 1.5, and 2.0 seconds) was also very reliable (ICC = 0.77–0.93). Table 4 shows result of 1-way ANOVA. No significant differences were found among the means of the 3 tempos. Table 5 shows the correlations among the 3 tempos. All correlations were significant. Moderate correlations were found between 2.0 and 1.5 seconds, and high correlations between 2.0 and 1.3 or 1.5 and 1.3 seconds. No significant differences were found among the correlation coefficients.
A successive choice reaction test was developed to assess the agility of open skill sports athletes. For practical purposes, it is necessary to set an adequate tempo and to examine the reliability of this test. It is possible that the difficulty and reliability of the test differ by tempo. This study aimed to examine the above problems.
Although we hypothesized that a test with a shorter tempo is unreliable, the ICC of every tempo used was >0.77 (ICC = 0.77–0.93). This hypothesis was rejected, and it was judged that all tempos have high reliability. It is necessary to examine reliability when making up a new test. In addition, high reliability of evaluation variables is important for the practical application of the successive choice reaction test. Generally, a test is considered reliable when the same subjects repeat the same test more than twice and the results are identical. This study conducted the test on different days and examined the test results. The ICC >0.75 (3) or 0.70 (6) is considered a fair standard of reliability. The ICC of the test in each tempo was >0.77. This study was conducted on different days, the reliability of which is generally lower than that between trials, considering the subject's physical burden. The ICC of tempos 1.5 and 2.0 seconds was very high. Also, in comparison to the reliability between the trials of the other agility tests (505 test: ICC = 0.90, Modified 505 test: ICC = 0.92, L run: ICC = 0.95, Reactive agility test: ICC = 0.93) (4) (change of direction speed test: ICC = 0.86, reactive agility test: ICC = 0.93) (14), the above values were larger or equal. From the above, the reliability of the present successive choice reaction test is considered to be high also in any tempo.
Stimulus presentation tempo was set 1.3, 1.5, and 2.0 seconds in this study. If a stimulus tempo is too fast, the subjects would not be able to achieve a successive choice reaction test. Conversely, if it is too slow, the test is almost the same as a choice reaction test performed from a static state. Thus, the stimulus tempo is very important for a successive choice reaction test. All the subjects could complete the present test without being late to the next stimulus. In addition, the reaction time of the successive choice reaction test (1.21–1.23 seconds) was slower than that of the general whole-body choice reaction test (0.99 seconds). In the latter test, the subjects wait for a stimulus presentation at a static state and react, but in the former test, they receive successive stimuli at dynamic state and need to react quickly. Therefore, reaction time in the latter test is considered to be slower than that in the former test. In short, it is judged that the present results are valid, and that the stimulus tempos of 1.3, 1.5, and 2.0 seconds selected in this study were adequate.
Although it was assumed that a shorter tempo would result in a slower successive choice reaction time, insignificant differences were found among the 3 tempos selected this study. The present test requires subjects to react to the stimulus while taking a stable posture by presenting successive stimuli. For the dual task, the more difficult main task demands a higher attention (5) and as a result, performances of the secondary task decrease (7,9,10). In the case of the short tempo, a short stimulus interval causes the posture stabilization time to decrease. Thus, it was considered that a stable posture requires increased attention, and consequently the reaction time is late.
The stimulus tempos used in this study (1.3–2.0 seconds per time) may have been a range without affecting measured values, and thus, a difference among the 3 tempos was not found. When using quite late tempos, some characteristics were lost, such as a successive choice reaction test, and significant differences may have occurred. The effects of fore period (FP) are also considered to be a significant reason. The FP means an interval from notice stimulus to reaction stimulus in reaction time measurement. Generally, reaction time is shorter when the notice stimulus exists. When fixing the FP, the longer it is, the shorter the reaction time is, and the shorter it is, the longer reaction the time is (8,15). Variation of reaction time by the FP as the above is caused by preparing to react and being able to meet the stimulus by predicting the FP time (10,11). Because the present test repeats stimuli at a constant interval, the preceding stimulus may play a role of a notice stimulus. Assuming the above, it was considered that subjects would be able to meet the timing in the shorter tempos with ease and would be able to shorten their reaction time. As a result, although the time with a shorter tempo tends to be late due to an increase of attention demand, it is inferred that the time difference is compensated by the effect of the FP, and that results did not differ. Hence, it is hypothesized that a successive choice reaction test with any tempo is valid for evaluating the agility of athletes majoring in open skill sports.
The subjects in this study were male university students majoring in sports. All the subjects had athletic experience and a relatively high physical fitness level. The athletes majoring in closed skill sports were included also. It is unclear whether the stimulus tempo used in this study is valid or not when using as subjects the top players majoring in open skill sports or general people with inferior physical fitness. From now on, it will be required to examine adequate tempos using the above groups.
The successive choice reaction test developed in this study can evaluate agility, in which subjects react quickly and adequately to an unknown stimulus from a dynamic state. It is indispensable for open skill sport athletes to adequately assess the above ability. It was judged that 3 tempos (1.3, 1.5, and 2.0 seconds) can use the successive choice reaction, because they are very reliable. Thus, this test is a practical agility test for open skill sports athlete. Agility is a very important element of physical fitness for open skill sports athletes. This test adequately assesses their agility and is useful in planning training prescriptions based on each athlete's unique characteristics. This test is also likely to discover new talented open skill sports athletes.
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Keywords:© 2013 National Strength and Conditioning Association
agility; open skill; reliability of test