Introduction
Reaction time (response time) has been defined as the time between the detection of a sensory stimulus and subsequent behavioral response (22). Collet (5) defined total reaction time as the time from the gun signal until the athlete's production of force against the starting blocks. This includes the sound traveling time between the sound source and the athlete, the athlete's reaction to the sound, and the mechanical delay of false start equipment integrated in the start block (16,17). According to the International Association of Athletics Federations (IAAF) competition rules, a reaction time less than 100 ms is considered a false start.
Reaction times can be an important determinant of success in the 100-m sprint, where medals are often decided by hundredths or even thousandths of a second. Therefore, a poor start or long reaction time can rule an athlete out of the medal hunt in a 100-m sprint competition. Reaction time to sensory stimuli has been widely examined in the literature and on various populations (18,21,22).
Unfortunately, only a few studies have examined track and field sprinters' reaction time and their moderators; Mero et al. (16) and Smirniotou et al. (20) reported no correlation between reaction time and performance level. Delalija et al. (9) observed a significant correlation between reaction time and sprint results from the 2004 Olympic Games in Athens. Meckel et al. (14) found significant differences between fast and average sprinters, whereas no differences were observed between the groups of fast and slow sprinters. The literature also remains unclear for possible gender differences in track and field; Mero et al. (16) concluded that the average reaction times for females are longer than those for males, and Dapena (8) does not necessarily support the claim by Mero et al. (16). Collet (5) reported that sprinters' reaction times decreased from one round to another toward the final for the 8 finalists. However, no available studies have so far examined world-class sprinters' reaction times related to body height or analyzed the development of reaction time through different age categories. Additionally, most of the previously published studies have examined competitions using the loud gun starts, a system that has been criticized for not delivering the “go” signal to the different lanes at the same time (2,8).
Therefore, we have created a database of reaction times, collected under highly standardized conditions based on 100-m sprint result lists from world championships for youths and seniors between the years 2003 and 2009. This provides the potential for addressing several different questions related to reaction times among world-class sprinters. Therefore, the purpose of this study was to examine and analyze reaction times of 100-m sprints from world championships and take a deeper look at its function and relation to athletes' performance level, body height, gender, heat round, and age.
Methods
Experimental Approach to the Problem
In this study, 100 m sprinters' reaction times were defined as dependent variable, whereas 100-m performance level, body height, gender, heat round, and age were defined as independent variables. All data were collected from different IAAF world championships for youths and seniors in the time period 2003–9 (Table 1), which were presented in the IAAF official website through the competition archive (12) and biography section (11). Only the 100-m competitions were included because it has been shown that reaction time increases from short dashes to longer sprints (5). World championships before 2003 and after 2009 were excluded because of different false start rules. The 2004 and 2008 Olympic Games were also excluded from this investigation because of different reaction time monitoring systems.
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Table 1: Description of competition with corresponding subjects.*
The meet organizer was responsible for timing, reaction time monitoring, heat seeding, lane draws, and further qualification/advancement in accordance to the IAAF competition rule guidelines (11). Body height and date of birth were identified for each athlete by self-report through the sign up procedures administrated and controlled by each of the national athletics federations, including passport identification.
Subjects
Data were collected from 1,319 sprinters in the age range 16–47 years, representing a broad range of performance levels and with varying training background. Athletes aged 16 or 17 years on the 31st of December in the year of the competition are allowed to participate in the World Youth Championships. For the World Youth Championships, only athletes aged 16–19 years may compete. Athletes younger than 16 years were not allowed to enter in the senior World Championships (11). In total, 1,719 reaction times formed the basis of this investigation. The athletes signed up and participated voluntarily for these competitions on the basis of being timed; thus, no informed consent was obtained. This study was approved by the Ethical Committee of Nordland University.
Procedures
All competitions included in this investigation were arranged in the middle of the summer (July or August) and were (in an athletics context) considered the most important competition of the year for the participants. All athletes had to qualify to the championships in accordance to the entry standards set by the IAAF; thus, familiarization with the competition procedures was ensured. On the first competition day, initial heats were held in the morning or middle of the day (between 10 AM and 2 PM), whereas the round 2 races were held in the afternoon or evening (between 6 and 9 PM). On the second day, the semifinals and finals took place in the afternoon or evening (between 4 and 10 PM), intercepted by a 1.5- to 3-hour break. The athletes followed their individual warm up routines until the obligatory call room procedures 20 minutes before the start.
Regarding nutrition, hydration, sleep, and physical activity, the athletes were assumed to have prepared themselves as they would for the most important competition of the year. All subjects were familiar with the competition procedures through national qualifications.
Statistical Analyses
All data from the database were transferred to SPSS 17 (SPSS, Inc., Chicago, IL, USA) for analyses. First and for all variables in this study, the normality distribution of the data was explored by histogram plot and tested using Shapiro-Wilk test. Then descriptive statistics were calculated and reported graphically together with the 95% confidence interval (CI).
In the percentile analyses, all athletes from 2003 to 2009 world championships were included, and the reaction times were subtracted from the 100 m times to isolate running time performance from reaction time performance. Each athlete's fastest running time and their corresponding reaction time were included in the analyses; then, the relationship between reaction time and 100 m running performance were calculated using Pearson correlation coefficient (r).
In the performance-level analyses, the athletes were divided into 4 performance level categories, namely, round 1 athletes, round 2 athletes, semifinalists, and finalists. Furthermore, each athlete was represented once with their best position from the world championships 2003–9. In the event of an athlete attaining the same position in more than one championship, the fastest running time and the corresponding reaction time were included in the analyses.
In the heat round analyses, only finalists from senior level were included. In the event of an athlete attaining the same position in more than one championship, the fastest running time and corresponding reaction time from round 1, round 2, semifinal, and final were included in the analyses.
In the age analyses, athletes were divided into 6 age groups: younger than 18, 18–19, 20–22, 23–25, 26–29, and older than 30 years. The athlete's age was calculated based on their date of birth and the competition date. In the event of an athlete falling under the same age group twice through the 2003–9 championships, the fastest running time within that age group and the corresponding reaction time were included in the analyses.
For all analyzed variables in this study, if the data were found to follow a normal distribution, the differences in the reaction time between the variables analyzed were determined using a 1-way analysis of variance followed by Tukey's post hoc test. However, if the data were not normally distributed, the nonparametric Kruskal-Wallis test was assessed, followed by Mann-Whitney Test. The level of significance was set at p ≤ 0.05 for all analyses.
Results
With regard to reliability, all competitions included in this investigation were arranged in an athletics context, considered the most important competition of the year for the participants. All athletes had to qualify to the championships in accordance with the entry standards set by the IAAF; thus, familiarization with the competition procedures was ensured. All subjects were familiar with the competition procedures through national qualifications. Thus, we have not conducted any performance testing for the purpose of reliability; however, because all the data presented in this study were collected under highly controlled and standardized procedures, we believe they are reliable.
Figure 1 presents percentile data of the athletes' reaction time from the IAAF championships in the time period 2003–9. There was a significant (p < 0.01) relationship between reaction time and 100 m running time for both male (r = 0.292) (reaction time = 0.166 ± 0.030 seconds) and female (r = 0.328) (reaction time = 0.176 ± 0.034 seconds). This relationship had a shared variance of 8.5 and 10.8% for males and females, respectively. Mean 100 m running time was 10.8 ± 0.6 seconds (±SD) for males and 12.0 ± 0.8 seconds for females. No relationship was observed between reaction time and body height.
Figure 1: Reaction time for men and women in percentiles.
Figure 2 demonstrates that male finalists had a substantially (p < 0.05) shorter reaction time (0.142 ± 0.017 seconds) compared with semifinalists (0.153 ± 0.022 seconds), athletes from round 2 (0.155 ± 0.020 seconds), and athletes from round 1 (0.161 ± 0.024 seconds). Furthermore, the semifinalists' reaction times were significantly shorter (p < 0.05) than round 1 athletes.
Figure 2: Mean reaction time and 95% confidence interval for athletes who went out of competition at different performance level categories.
Corresponding results for females show that reaction times for round 1 athletes (0.175 ± 0.029 seconds) were significantly longer (p < 0.05) than finalists (0.154 ± 0.025 seconds), semifinalists (0.153 ± 0.018 seconds), and round 2 athletes (0.161 ± 0.018 seconds). Semifinalists had a significantly shorter reaction time (p < 0.05) compared with round 2 athletes. No further differences were observed. Semifinalists achieved the shortest reaction times for females (Figure 2).
Figure 3 shows the development in reaction times through different heat rounds for the finalists' best performance in the time period 2003–9. For females, reaction times in the semifinals were significantly shorter (p < 0.05) compared with round 1 and 2. No significant heat round development was observed for males. However, the 95% CI demonstrates a slight trend toward faster reaction times from the preliminary rounds to the finals. The shortest reaction times were observed in the semifinals for females and in the finals for males.
Figure 3: Mean reaction time and 95% confidence interval of the finalists' reaction time development through competition.
Figure 4 demonstrates that male athletes younger than 18 years had a significantly longer reaction time (0.170 ± 0.031 seconds) (p < 0.01) than the other age groups. Male athletes in the age category of 18–19 years had a significantly longer reaction time (0.164 ± 0.030 seconds) (p < 0.05) compared with the athletes in the age category of 26–29 years (0.150 ± 0.017 seconds) but not with the age group of 20–22 years (0.160 ± 0.024 seconds) and 23–25 years (0.158 ± 0.026 seconds). For females, a significantly longer reaction time was observed for the athletes younger than 18 years (0.180 ± 0.039 seconds) compared with other age groups (p < 0.05). The 18- to 19-year female athletes had a significantly longer reaction time (0.171 ± 0.029 seconds) (p < 0.05) compared with the female athletes older than 30 years (0.153 ± 0.020 seconds). No further significant differences were observed between age groups.
Figure 4: Mean reaction time and 95% confidence interval of the reaction time at different age categories.
The results show that the 100-m performance level among male sprinters peaks in the age range of 26–29 years: younger than 18 years (11.16 ± 0.52 seconds), 18–19 years (10.86 ± 0.41 seconds), 20–22 years (10.73 ± 0.51 seconds), 23–25 years (10.56 ± 0.61 seconds), 26–29 years (10.40 ± 0.36 seconds), and older than 30 years (10.54 ± 0.49 seconds). Corresponding results for female sprinters demonstrate an improvement in 100 m performance through almost all the age categories: younger than 18 years (12.37 ± 0.71 seconds), 18–19 years (12.17 ± 0.72 seconds), 20–22 years (12.31 ± 1.08 seconds), 23–25 years (11.73 ± 0.84 seconds), 26–29 years (11.58 ± 0.55 seconds), and older than 30 years (11.46 ± 0.54 seconds).
Discussion
The percentiles in this study show that the reaction times of male and female 100-m sprinters generally vary between 0.14 and 0.20 seconds (Figure 1). The 10th percentile of reaction times was approximately 0.02 second faster than the average. These relatively modest variations can still be decisive in a sport where competitive placing is separated by mere hundredths of a second. To our knowledge, this study is the only one to date with so many participants at a high level that uses only data in which only the silent gun system was used. Therefore, no other study is available for comparison purposes.
Our data show a weak significant correlation between reaction time and 100 m running time for both males and females. Reaction time and 100 m running time shared only approximately 10% of common variance. The detection of the relationship between reaction time and performance in 100 m running time may have been facilitated by the large sample size and the large spread in performance level observed in this study. No significant relationship has been observed in smaller groups of subjects of approximately the same performance level (14). However, a weak but significant correlation has been reported in larger heterogeneous groups (9,20). Mero et al. (16) concluded in his review article that there was no correlation between reaction time and performance level. However, his review was based on studies in which the loud gun system was used. Furthermore, a possible explanation for the weak correlation between reaction time and performance observed in this study could be that both variables are largely determined by the same physiological factors. As early as 1976, Costill et al. (6) found that sprinters had far more type II fibers than athletes from other sports. Muscle fiber type composition determines, to a large extent, anaerobic power and neuromuscular conditions such as the arrival of the stimulus at the sensory organ, conversion by the sensory organ to a neural signal, neural transmission and processing, and muscular activation (5,17). Similarly, neuromuscular conditions may explain the relationship between simple jumping tests, such as squat jump and countermovement jump, and reaction time and 100 m time in sprinters (20).
In theory (19), taller athletes could have a slower reaction time than shorter athletes with otherwise identical physiological characteristics because of the distance the nerve impulse has to travel. However, no relationship between body height and reaction time was observed in this study.
The results of this study show that males and females have an average reaction time of 0.166 ± 0.030 seconds and 0.176 ± 0.034 seconds, respectively (Figure 1). In addition, the results show that the reaction times of the male athletes were significantly shorter (p < 0.01) than the female athletes' reaction times. Our findings are consistent with Mero and Komi (15) who showed that male sprinters had a significantly shorter reaction time than female sprinters at the Finnish national level. Other studies of elite sprinters have also reported a significant sex difference of approximately 0.02 seconds (1,8). We are not aware of any studies that are able to explain this difference, but Spierer et al. (22) have found that women react faster to a visual stimulus compared with sound-based stimulus. Adam et al. (1) explain that differences in reaction time between gender are related to information processing speed, whereas Spierer et al., (22) indicated that the processing speed could be caused by an inherent neurological function that may differ by gender. We can also speculate that it may be because of factors such as genetics, training background, and, in particular, differences in performance level. The data for both males and females show significant differences in reaction time between athletes of different performance levels (Figure 2). However, this cannot fully account for the sex-related difference, as generally observed in this study that the reaction times of female runners at a given 100-m performance level is shorter than that of male sprinters of the same level (Figure 2). Furthermore, even though the best female group (race time = 11.46 seconds) has a longer 100-m sprint time than the slowest male group (race time = 11.16 second), these 11.46-second female athletes have better start times than the 11.16-second male athletes (Figure 3). This may be because these female athletes generally have more years of dedicated training behind them compared with the male athletes. The female runners in the above performance category are vying for international medals, whereas the men who run as fast barely qualify for the World Championships. Collet (5) found a shorter reaction time in elite sprinters with a good training background and high level of experience. It was suggested that this was because of the older and more experienced athletes being able to memorize and anticipate starting procedures to a greater degree than inexperienced sprinters. Colakoglu et al. (4) proposed that reaction time is a motor skill that can be developed through training and maturation. Whether differences in reaction time are because maturation (age) or training background cannot be determined from data in this study or other studies. Reaction time is defined as the time taken from the firing of the start signal to the athlete generating a force (pressure) against the starting blocks (5). Athletes with high maximal strength and rate of force development in the leg extensors will be able to develop a force faster than athletes with poorer physical characteristics. This could be an explanation for the difference in reaction time between males and females.
Analyses of male finalists showed that their reaction time in the final was significantly shorter (p < 0.05) than in the semifinals, round 2, and round 1 (Figure 3). Female finalists had shorter reaction times in the final than in round 1 and round 2 (p < 0.05). However, from the semifinal to the final, there were no significant differences in reaction time for females (Figure 3). Collet (5) found similar results when studying semifinalists and finalists in the Olympic Games and World Championships in the period 1987–97. Reaction times in our study were around 0.02 seconds shorter than in the investigation by Collet (5). However, the results are not fully comparable because of differences in false start rules and measuring instruments used. In the 1990s, each athlete was permitted 2 false starts before he or she was disqualified. Our data collection covered the period between 2003 and 2009 when only 1 false start per heat was permitted. The old rules therefore allowed athletes greater scope to anticipate when the starting signal occurred. It is not surprising that the reaction time of finalists is reduced from the initial rounds to the final. The best athletes do not need to perform optimally in round 1 because they are relatively certain to go through to the next round of the competition. The focus for these athletes is therefore on saving energy and not risking a false start. The female athletes in this study had a markedly slower reaction time in the final compared with the semifinals, although this difference was not statistically significant (Figure 3). Increased external pressure and fear of disqualification may inhibit the ability to react quickly. The arousal levels of some athletes are likely to have been higher than optimal. It has been shown that if arousal exceeds a certain level, performance becomes impaired (3,24).
The results show a significant difference in reaction time (p < 0.01) for male athletes younger than 18 years of age compared with all other age groups (Figure 4). Furthermore, male athletes aged 18–19 years old had a slower reaction time (p < 0.05) than athletes in the age group 26–29 years. The data for female athletes showed that the reaction times of athletes younger than the age of 18 years were significantly slower than in all the other age groups (p < 0.05). The trend for both female and male athletes was that the reaction time decreased with increasing age. This is consistent with results from previous studies of elite sprinters (5). A key question is why reaction time decreases with increasing age? Neither this study nor other studies have so far been able to provide a satisfactory answer to this question, and the suggested explanations therefore remain pure conjecture. Maturation and training could be possible explanations. Most researchers who have studied reaction time propose that an individual's ability to react quickly to a stimulus is to a large extent related to the nervous system (2,5,15,17) and muscular system (2,14,20). This may explain the relationship between vertical jump height, reaction time, and performance in male sprinters (20).
The significant improvements in reaction time at the age of late 20s could also be caused by the differences in the performance level between the different age categories. As we found a significant correlation between reaction time and 100 m running time, this could affect the reaction times as a function of age. Several studies of elite athletes have shown that it takes many years of training to develop physical ability and the performance determining factors necessary to win medals at international championships (7,13,23). Another explanation could be that older athletes have a greater genetic predisposition for reacting and running quickly. A dropout study showed that those individuals who gave up athletics at the elite level were athletes who had not experienced progress or achieved their goals over the last couple of years (10). This dropout may have led to athletes in the older age categories having a better genetic predisposition for fast reaction times and sprint running performance than athletes in the younger age categories.
The data indicate that females in this study showed shorter reaction times and increased performance in 100 m with increasing age. To our knowledge, there are no obvious physiological explanations for why female sprinters reduce their reaction time in their 30s, whereas male athletes achieve the fastest reaction times in the second half of their 20s. One possible reason may be a greater dropout of female athletes with increasing age (10), so that only the very best athletes comprise the majority in the oldest age categories.
Practical Applications
The present investigation demonstrates a significant relationship between reaction time and 100 m running time of sprinters from a broad range of performance levels. This relationship indicates that reaction time effects performance in 100-m sprint. Furthermore, the variations of the reaction time found in this study can be decisive in a sport where competitive placing is separated by mere hundredths of a second. The fact that our results showed that reaction times of male athletes were significantly shorter than female athletes, the slower reaction time in females' finals compared with females' semifinals, and the trend of reaction time development through age for both males and females suggest a different training strategies approach by both male and female coaches to achieve faster reaction times. Practitioners should explore possible training methods to improve the athletes' reacting skills. Future research could focus more on the cause-effect relationships between reaction time and performance level. Mental training of sprinters might ensure an optimized arousal level at the start line to obtain fast reaction times. A poor reaction time can definitely rule an athlete out of the medal hunt.
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