Introduction
The standing long jump is a common standardized test used by coaches, teams, and sports organizations to evaluate athletic potential and performance. In addition, there are a multitude of athletic combines and performance facilities where coaches and athletes gather to evaluate and demonstrate athletic aptitude using the standing long jump test. The wide acceptance of the standing long jump test can be seen through its incorporation within a variety of sports (e.g., football, basketball, volleyball) and also at various levels of expertise, from high school to the professional ranks (14,15). Although the standing long jump is a widely used test, the impact of verbal instructions on jump performance, for training and testing purposes, has been largely ignored, leading to potentially disparate findings in performance and reliability.
Empirical findings reported in a recent study by Porter et al. (12) demonstrated that standing long jump performance was significantly influenced by the attentional focus promoted through verbal instructions. The authors found providing instructions that encouraged subjects to think about body movements significantly reduced jump performance compared with jumpers who received verbal instructions encouraging them to think about the effects of their movements. The results of the study highlight the importance of using appropriate and consistent verbal instructions when conducting a standing long jump test. The findings also illustrate the need for standardized verbal instructions to foster not only optimal performance but also testing reliability. This is an extremely important consideration for coaches to factor into their training and testing protocols. For example, the findings reported by Porter et al. (12) suggest that coaches can have a significant impact on performance by simply changing 1 or 2 words of the verbal instructions they provide to athletes. Using effective methods of verbal instruction can be a critical tool for coaches in fully maximizing performance. A review of many popular testing manuals and texts revealed no discussion of the effects of verbal instructions on performance or test reliability (2,3,4,5,8,9). One reason for this lack of information is likely due to poor communication between scientists and the coaching community (13).
Through the use of verbal instructions, practitioners can invoke 2 types of attentional focus strategies. The first is called an internal focus of attention. Athletes adopt an internal focus of attention when coaches provide instructions that direct them to think about specific movements or body parts while executing a motor action (17). An example would be a coach instructing athletes to focus on their arm swing while throwing an implement in track and field. The second strategy is referred to as an external focus of attention. An external focus of attention is used when athletes think about the effects of their movements during the execution of a performance (17). For example, instead of focusing an athlete's attention to the arm movements (internal focus of attention), the coach provides instructions that are directed toward the implement being thrown. The specific type of attentional focus an athlete adopts, whether it is internal or external, is readily influenced by the verbal instructions provided by the coach or test administrator. Not surprisingly, what a coach says to an athlete greatly influences what the athlete thinks about. The performance benefit of an external focus of attention strategy has been observed in a wide range of motor tasks within the motor learning and control literature (1,7,11,18,19,21). Moreover, this robust performance effect has been demonstrated with novices, experts, and patient populations (6,10,18,20).
It is important to note that providing verbal instructions that foster an external focus of attention does not mean that movements of an action or motor skill are not taught. Instead, it highlights the importance of providing verbal instructions that guide movements in a more efficient manner, so that the individual movements do not have to be explicitly communicated. It may seem counterintuitive that if a coach desires to change an athlete's movement mechanics that they should avoid referencing the body and its movements. Doing so will likely depress motor skill performance and learning because it elicits an internal focus of attention. However, motor behavior research has consistently demonstrated that a far more effective way to immediately and permanently change mechanics is to creatively provide instruction or feedback that directs attention externally. For example, perhaps a coach observes an athlete execute the power clean with the barbell too far from his/her body. This is a behavior that the coach could correct by simply telling the athlete to “bring the hands and arms closer to the body” when executing the lift. This type of instruction would promote an internal focus of attention because the hands, arms, and body are referenced. An alternative form of instruction may be to “bring the bar in” when executing the lift. This similar, but subtly different, form of instruction promotes an external focus of attention because the emphasis is on the effect or outcome of the movement rather than on the movements of the body. Numerous motor learning and control studies demonstrate wide support for an external form of verbal instruction (i.e., focus on bar) as a far superior method of communicating movement changes to athletes rather than an internal form of verbal instruction (i.e., focus on hand, limb, and body) (for a review see (17)).
The purpose of the present study was to evaluate jump performance and peak force characteristics associated with various focus of attention strategies. The study by Porter et al. (12) described above demonstrated a significant benefit in jump performance when subjects were provided verbal instructions that promoted an external focus of attention. In discussing their results, the authors suggested that the difference in performance was likely because of the subjects in the external focus condition applying greater forces to the ground than the internal focus group. However, the authors failed to measure the peak force characteristics associated with each attentional focus condition to validate this conclusion. Therefore, the present study measured the peak force characteristics of both the internal and external conditions to verify if the superior jumping performance of the external focus group was in fact because of a significant increase in peak force production. It was hypothesized that the external focus of attention group would exhibit not only superior jump performance compared with the internal focus of attention group but also greater peak forces compared with the internal focus of attention group. Such a finding would not only add to the scientific literature by testing predictions made in previous research (12) but also offer a partial explanation for the underlying mechanisms for why directing attention externally is superior to using an internal focus of attention. Both of these considerations are important for the scientific community and strength and conditioning professionals.
Methods
Experimental Approach to the Problem
This study was conducted using a within-subject experimental design to explore the performance differences in the standing long jump when adopting internal and external focus of attention strategies. With respect to the dependent variables, the study used distance jumped as the outcome measure and peak force as the kinetic measure. Distance jumped was used as the outcome measure because it is the most readily available measure used by practitioners. Peak force was used as a dependent variable because it provides movement production-related information that explains “why” there may be differences between the outcome measures of both experimental conditions.
Untrained recreationally active subjects were assigned to both experimental conditions in which verbal instructions were provided to promote either an external or internal focus of attention. Attentional focus instructions were counterbalanced to eliminate the possibility of order effects. After a 5-minute warm-up, all subjects completed a total number of 5 standing long jumps. Jump distance was measured after each jump, and peak forces for both feet were measured during each jump. Peak force measurements of the left and right foot were combined for the analyses. Statistical analyses were conducted to identify significant differences between the internal and external focus group for both dependent variables: jump distance and peak force.
Subjects
Twenty-one male (n = 10) and female (n = 11) undergraduates participated in the experiment. Untrained recreationally active subjects were recruited from a general undergraduate population; they did not participate in any collegiate, club, or professional sports teams. The average age, height, and weight of the subjects were 21.3 ± 1.74 years, 169.1 ± 10.1 cm, and 67.4 ± 10.5 kg, respectively. Participating subjects read and signed an informed consent. The University's Institutional Review Board approved all forms and experimental methods. Subjects were required to wear athletic clothing and shoes during the experiment. Subjects were naive to the purpose of the experiment.
Procedures
On entering the laboratory, each subject was provided an informed consent. Once subjects provided consent to participate in the study, subjects performed a 5-minute warm-up on a stationary bike at a self-selected intensity level. On completion of the warm-up and before their first jump, subjects were provided with a 2-minute seated rest. The first jump, for all subjects, served as a baseline. The only instruction provided before the baseline jump was “jump as far as you can.” After the baseline jump, each subject performed 4 additional jumps. Each jump was followed by a seated 2-minute rest period. Before each jump, subjects were provided verbal instructions, adapted from Porter et al. (12), which invoked either an internal or external focus of attention. Subjects given internal focus verbal instructions were told to “Jump as far as you can. While you are jumping, I want you to think about extending your knees as rapidly as possible.” Subjects given external focus instructions were told to “Jump as far as you can. While you are jumping, I want you to think about jumping as close to the green target as possible.” The green target (or cone) for the external focus of attention group was placed 4.57 m from the start line and was not present for the internal focus condition. External and internal focus of attention instructions was counterbalanced across subjects to eliminate order effects. Moreover, subjects performed 2 consecutive jumps under each experimental condition. For example, subject 1 performed 2 consecutive jumps using an external focus of attention, followed by 2 additional jumps using an internal focus of attention. Subject 2 performed the first 2 jumps under an internal focus of attention, whereas the last 2 jumps were performed with an external focus of attention. This process was repeated for all subjects. After each trial, jump distance was measured by measuring the rear heel closest to the start line. Before the baseline jump, subjects were instructed to hold their position after completion of the jump so that an experimenter could measure their performance. Subjects were not provided augmented feedback about their jump distance. Peak force measures were calculated for each foot during the execution of each jump. The peak force measurements for each foot were combined for the analyses.
Apparatus and Task
The experiment was performed in a controlled research laboratory. Subjects jumped off each force platform onto a wooden surface. Vernier Force Plates (model number: FP-BTA) collecting vertical force components at 120 Hz were used. After each jump, experimenters measured the jump distance by measuring the distance between the start line and the heel of the foot nearest to the start line using a tape measure. Experimenters measured each jump in inches and later converted each performance to centimeters (cm) for the analyses.
Statistical Analyses
The statistical analyses were performed using the SPSS version 18. A 3 × 2 (condition × sex) analysis of variance (ANOVA) with repeated measures for the condition factor was performed to evaluate differences in jump distance between both experimental conditions and the baseline. In addition, a separate 3 × 2 (condition × sex) ANOVA with repeated measures on the condition factor was performed to evaluate peak force between both experimental conditions and the baseline. Both trials within each attentional focus condition were averaged for the analyses. The criterion for significance was set using an alpha level of p ≤ 0.05. To evaluate the effect size for any significant findings, Cohen's effect size (ES) statistics (Cohen's d) were calculated. Effect sizes were based on partial Eta-squared analyses.
Results
For jump performance, a 3 × 2 (condition × sex) ANOVA with repeated measures on the condition factor revealed a main effect for condition F2,38 = 15.2, p < 0.05, ES = 0.444. Multiple comparisons using least significant difference revealed the external focus condition (153.6 ± 38.6 cm) to have jumped significantly further than the internal condition (139.5 ± 46.7 cm) and baseline condition (133.8 ± 35.7 cm) (Figure 1). In addition, there was a main effect for sex, F1,19 = 34.2, p < 0.05, ES = 0.643. Specifically, male subjects jumped further than the female subjects in the baseline (men = 160.7 ± 19.9 cm, women = 109.3 ± 28.5 cm), external focus (men = 186.8 ± 19.2 cm, women = 1,23.5 ± 23.6 cm), and internal focus (men = 176.03 ± 29.7 cm, women = 109.3 ± 28.5 cm) conditions. There was no interaction observed between the condition and sex factors, F2,1 = 3.08, p > 0.05.
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Figure 1: Mean jump performances for each condition: baseline, internal focus of attention, and external focus of attention. Alpha level = 0.05.
For peak force, a 3 × 2 (condition × sex) ANOVA with repeated measures on condition revealed no main effect for condition, F2,38 = 1.88, p > 0.05. The external focus condition produced a mean peak force of 1429.8 ± 289.1 N, whereas the internal focus condition and baseline conditions produced mean peak forces of 1,453.7 ± 299.7 N and 1,398.9 ± 293.4 N, respectively (Figure 2). The analysis did reveal a main effect for sex, F1,19 = 1,075.6, p < 0.05, as the male subjects produced significantly more peak force than the female subjects in the baseline (men = 1,604.1 ± 200.5 N, women = 1,212.3 ± 235.7 N), external focus (men = 1647.7 ± 207.3 N, women = 1,231 ± 194.8 N), and internal focus (men = 1666.3 ± 217.8 N, women = 1,260.5 ± 225.2 N) conditions. There was no interaction observed between the condition and sex factors, F2,1 = 0.089, p > 0.05.
Figure 2: Mean peak force characteristics for each condition: baseline, internal focus of attention, and external focus of attention.
The intraclass correlation coefficient reliabilities (ICCRs) determined that the dependent variable for jump distance was reliable for the external (r = 0.944) and internal (r = 0.967) focus of attention conditions. In addition, reliability was also high for the peak force measurements for the external (r = 0.940) and internal (r = 0.910) focus of attention conditions.
Discussion
The standing long jump has become a widely used test to assess power, athletic potential, and motor performance. Although this test is frequently used by practitioners within a variety of sporting contexts, the effects of verbal instructions on an athlete's focus of attention and its influence on performance are not well understood. Recently, Porter et al. (12) found that subjects who adopted an external focus of attention performed better than those who adopted an internal focus of attention while performing the standing long jump. Although the authors did not measure force production, they suggested that differences in jump performance were likely because of the external focus of attention condition, enabling subjects to produce greater forces compared with the internal focus condition. The purpose of the present study was to replicate the results of Porter et al. (12) and to identify the peak force characteristics associated with both an internal and external focus of attention.
It was hypothesized that the external focus of attention condition would promote greater jump distances and greater peak force values compared with the internal focus of attention condition. Based on the results of the present study, the hypotheses were partially supported. Specifically, the results of this study replicated the findings of Porter et al. (12) in which the external focus of attention condition exhibited greater jump distances than the internal focus of attention condition, regardless of sex. However, the results of the present study failed to validate the prediction that the increase in jump performance was the result of the external focus of attention condition generating more peak force compared with the internal condition. Clearly, other variables such as projection angle, muscle activation patterns, or differences in jump mechanics were possibly the cause of the observed outcomes. Additional research is needed to determine the exact underlying mechanism. Regardless, the present results provide meaningful and additional evidence that strength and conditioning professionals can effectively improve standing long jump performance by adopting verbal instructions that direct attention externally rather than internally.
According to Wulf (17), the performance differences between an external and internal focus of attention are best explained by the constrained action hypothesis. The hypothesis states consciously focusing on the movements of a motor action disrupt automatic motor control processes that regulate coordinated movements. When athletes actively focus and consciously control their movements, they interrupt automatic nonconscious motor behavior processes that normally control movements in an efficient manner. In contrast, directing attention externally to the movement effects allows the motor control system to naturally regulate and organize motor actions. As a result, movements are unconscious, fast, and reflexive.
The findings of Vance et al. (16) provide empirical support for the constrained action hypothesis at the neuromuscular level. In their study, participants who adopted an external focus of attention produced less muscle activity, as measured through electromyography (EMG), during a biceps curl when compared with subjects using an internal focus. According to the authors, the reduction in EMG activity exhibited by the external focus of attention group reflected greater economy of movement through a potentially greater efficiency in motor neuron recruitment. It is possible that a similar motor unit recruitment strategy was adopted by subjects in the present study.
The results of the present study revealed that there were no observed differences in peak force output between the internal and external focus of attention conditions. The constrained action hypothesis provides a plausible explanation for the lack of group differences. As previously stated, an internal focus of attention, or focusing on specific body segments, overrides and disrupts automatic motor control processes. As demonstrated in the study of Vance et al. (16), this disruption can be observed at the neuromuscular level through increased EMG activity of the involved muscles. Whereas the activity level increases, the efficiency in motor unit recruitment decreases with an internal focus of attention. Also, Zachry et al. (22) observed an increase in EMG activity in both the biceps and triceps brachii when subjects were asked to perform basketball free-throw shots. Even though subjects were instructed to focus on wrist flexion while performing the shot, the internal focus caused cocontraction of the biceps and triceps brachii, thereby reducing the degrees of freedom of the shooting arm. Zachry et al. (22) did not observe the same increased muscle activity of both the triceps and biceps brachii when subjects were instructed to focus on the center of the rear portion of the basketball rim (external focus of attention).
Within the present study, the lack of efficiency in motor unit recruitment may be responsible for the similar peak forces among the internal and external conditions but differing jump performances. Specifically, although both internal and external focus of attention conditions produced similar amounts of peak force, the timing component in which the force was applied may have been different. In other words, the external focus of attention condition may have outperformed the internal focus of attention condition because of differential impulse values. That is, performances within the internal focus of attention condition lacked the ability to apply maximal vertical forces over smaller periods, thereby producing a less efficient jump movement. However, additional research is needed to directly test this possibility.
An alternative approach for explaining the similar peak forces but differential jump performances between the internal and external conditions may also be explained by differences in the jumper's projection angle. That is, the external focus of attention condition may have used a more optimal angle of projection than the internal group. For example, the instructions that elicited an internal focus may have caused participants to add a greater vertical component to their jump. As demonstrated in the study of Zachry et al. (22), cocontraction elicited by an internal focus may have prevented the jumper from developing the appropriate balance between vertical and horizontal force productions, consequently depressing jumping ability. In contrast, the external condition was able to produce an optimal movement plan that efficiently combined both vertical and horizontal force components, resulting in a greater jump distance. Future research is needed to validate this conclusion.
Despite the mounting evidence about the negative performance effects that occur when using an internal focus of attention, many coaches continually provide athletes verbal instructions that direct attention to specific body segments. According to a study by Porter et al. (13), athletes competing at the United States of America Track and Field Outdoor National Championship reported that their coaches provided verbal instructions and feedback during practice, which elicited an internal focus of attention during competition. This is important to note from both training and testing perspectives. Although coaches provide much calculation in obtaining optimal physiological responses through specifically designed training protocols, their efforts may not fully come to fruition as the verbal instructions they provide to athletes may consequently depress motor performance. From a testing perspective, inconsistent verbal instructions that promote different types of attentional focus will likely lead to unreliable measurements.
In conclusion, the present study replicated the findings of Porter et al. (12) that demonstrated a significant improvement in standing long jump performance when adopting an external focus of attention. Whereas there was a significant difference in jump performance, there were no differences observed in peak force between the 2 conditions. Therefore, the observed differences in jump distance are likely because of differences in projection angle or impulse. It is important to note that the subjects within the present study were not elite-level athletes. Future research should address the influence of attentional focus on elite performers, as they possess well-established motor programs and movement strategies that may be differentially affected when compared with subelite athletes. Many important questions remain about how to best organize training environments to optimize performance. Throughout the article, we have proposed many avenues for future research. Only through continued investigation and collaboration with practitioners will the field of strength and conditioning accurately answer the questions related to eliciting the best performances from athletes.
Practical Applications
In addition to previous research, the findings of this study provide coaches a useful tool in training and will also help athletes increase performance when performing the standing long jump. Moreover, this study highlights the importance of providing standardized verbal instructions when administering a standing long jump test. Coaches and test administrators must take into account the type of verbal instructions they provide while training or conducting a standing long jump test. To obtain enhanced performance, instructions should be structured so that athletes are able to focus their attention to the effects of their movements or key features of the environment that guide the movements of the overall motor action. Examples include “jump as far past the start line as you can,” “find your personal best and try to jump past it,” or “pick a point in front of you and jump as close to the point as possible.” Coaches should avoid using verbal instructions that contain information about specific body segments or body movements. Moreover, testing manuals and texts that contain the standing long jump test item should include standardized verbal instructions that promote an external focus of attention, which in turn will provide more reliable assessments of human performance.
The results of the present study add one piece to the larger puzzle of understanding how to best instruct an athlete on how to most efficiently and effectively perform a motor skill. The methods presented in this study can easily be adopted by coaches and other practitioners and used when working with athletes. Coaches should continually question their methods and seek ways to improve their coaching abilities. Based on the present studies' findings, one simple way to immediately improve athletic performance is to ensure that athletes are continually directing their attention externally. Specifically, athletes who are involved with sports that require a maximum jump (e.g., track and field high jump) should always be encouraged to focus on the outcome of the task (i.e, clearing the bar) rather than on the movements needed to achieve success in the task (i.e., arching the back).
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