Kinetics, Kinematics, and Fixed Postures: An Exploration of How Attentional Focus Manipulation Enhances Movement.

There is debate in the literature regarding how manipulating the focus of attention (FOA) influences ground reaction forces during the standing long jump (SLJ) and gaps in understanding as to which phases of the SLJ are affected (takeoff, flight, and landing) and whether FOA manipulation benefits remain when tasks are performed in fixed body postures. P urpose: This study compared SLJ performance under external (EXT) and internal (INT) FOA conditions with free and fixed postures. M ethods: Twenty participants performed SLJs under EXT and INT FOA conditions while being allowed to swing arms freely and having to keep hands on their hips. Kinematics and kinetics were recorded using 3D-motion capture and force plates. Jump distances, projection angles, and ground reaction forces and impulses were compared across conditions using a 2 × 3 repeated measures ANOVA. R esults: Jump distances were significantly further with EXT FOA (p < .001). These differences were due to increases in the takeoff distance (p < .001) and landing distances (p < .001), with flight distances not being different between the conditions (p = .061). Peak horizontal ground reaction forces (p < .001) and impulses (p < .001) were both greater, while projection angles were lower (p = .002) in the EXT FOA condition. Co nclusions: Improvements in SLJ distance with an EXT FOA are due to the takeoff and landing phases; manipulating FOA does change forces during the SLJ; and that benefits of an EXT FOA are realized even when movements are performed with constrained body postures.

Short-term effects of a trunk modification program on patellofemoral joint stress in asymptomatic runners.

OBJECTIVES: To evaluate short-term effects of a four-week gait retraining program using visual feedback on trunk flexion angle, patellofemoral joint (PFJ) stress, lower extremity biomechanics and motor skill automaticity. DESIGN: Longitudinal interventional study. SETTINGS: University research laboratory. PARTICIPANTS: Twelve asymptomatic recreational runners (seven male and five female). MAIN OUTCOME MEASURES: Trunk kinematics as well as lower extremity kinematics and kinetics were assessed prior to training at week 1 (baseline) and week 2, 3, 4 and 8 (retention). PFJ stress was computed using a sagittal plane model. A dual-task procedure was performed to examine automaticity. RESULTS: At week 8, runners demonstrated 10.1° increase in trunk flexion angle (p < .001) and 17.8% reduction in peak PFJ stress (p < .001) compared to baseline. This is associated with a 16.8% decrease in knee extensor moment and less than 2.5° change in knee flexion angle. Participants also showed 33.3% increase in peak hip extensor moment and small reduction in peak ankle plantar flexor moment. Lastly, runners demonstrated automaticity of the modified skill with a dual-task cost of less than 3%. CONCLUSION: The gait retraining program is effective to elicit short term changes in trunk position, PFJ stress, and automaticity of the new motor skill.

Factors Contributing to Medial Tibial Stress Syndrome in Runners: A Prospective Study.

PURPOSE: Medial tibial stress syndrome (MTSS) is one of the most common overuse injuries sustained by runners. Despite the prevalence of this injury, risk factors for developing MTSS remain unclear. The purpose of this study was to prospectively evaluate differences in passive range of motion, muscle strength, plantar pressure distributions, and running kinematics between runners who developed MTSS and those who did not. METHODS: Twenty-four National Collegiate Athletic Association Division 1 cross-country runners participated in this study. Participants underwent a clinical examination documenting passive range of motion and muscle strength at the hips and ankles. Plantar pressure analysis was used to quantify mediolateral pressure balances while walking and 3D motion capture was used to quantify running kinematics. Participants were followed up for a 2-yr period during which time any runners who developed MTSS were identified by the team's certified athletic trainer. RESULTS: Runners who developed MTSS demonstrated tighter iliotibial bands (P = 0.046; effect size [ES] = 1.07), weaker hip abductors (P = 0.008, ES = 1.51), more pressure under the medial aspect of their foot at initial foot contact (P = 0.001, ES = 1.97), foot flat (P < 0.001, ES = 3.25), and heel off (P = 0.034, ES = 1.30), greater contralateral pelvic drop (P = 0.021, ES = 1.06), and greater peak amounts (P = 0.017, ES = 1.42) and durations (P < 0.001, ES = 2.52) of rearfoot eversion during stance phase. A logistic regression (χ = 21.31, P < 0.001) indicated that every 1% increase in eversion duration increased odds of developing MTSS by 1.38 (P = 0.015). CONCLUSIONS: These findings demonstrate that the development of MTSS is multifactorial, with passive range of motion, muscle strength, plantar pressure distributions, and both proximal and distal kinematics all playing a role. We suggest that coaches or sports medicine professionals screening runners for injury risk consider adopting a comprehensive evaluation which includes all these areas.

Does Focus of Attention Improve Snatch Lift Kinematics?

Recent motor control literature has demonstrated that using verbal instructions to direct a performer's attention externally (i.e., toward the movement outcome) enhances motor skill performance. The purpose of this study was to investigate how an athlete's focus of attention impacts kinematic performance of the snatch. Using a counterbalanced within-participant design, 12 competitively trained athletes (8 male and 4 female athletes) performed 2 instructional blocks of 3 snatch repetitions at 80% of their most recent training 1 repetition maximum. Blocks of internal and external instructions were given to the athlete in a random fashion. Results showed that, when focusing internally, athletes significantly (p ≤ 0.05) increased elbow velocity relative to focusing externally, whereas the external instructions significantly increased horizontal barbell velocity, relative to internal instructions. Additionally, an internal focus resulted in significantly larger barbell-cervical-hip angles at maximum height of the barbell compared with an external focus, indicating that the athletes squatted under the barbell too soon. This information adds to the literature suggesting small changes in coaching instructions can impact performance significantly. It is recommended that coaches use instructions that direct an athlete's attention externally, toward the movement outcome, rather than the action itself.

Standing Long Jump Performance With an External Focus of Attention Is Improved as a Result of a More Effective Projection Angle.

Investigators have recently demonstrated that standing long jump performance is enhanced when participants focus their attention externally instead of their leg action but found no differences when examining peak force. The purpose of this study was to examine kinetic and kinematic properties associated with the standing long jump that may explain disparities between an internal and external focus of attention. It was hypothesized that the external focus condition would exhibit greater impulse values and a more optimal projection angle (45°) than the internal condition. Twenty-one participants each performed 5 total jumps: 1 baseline jump, in which no focus instructions were given, followed by 4 remaining jumps in which either internal or external focus instructions were introduced in a counter-balanced manner. Analysis of variance revealed that the external condition jumped significantly farther than the internal and baseline conditions. Analyses of kinetic measures (i.e., peak force and impulse) revealed no significant differences among conditions. However, there was a significant difference between the internal and baseline conditions compared with the external condition with respect to projection angle. Specifically, participants in the external focus condition exhibited an average projection angle of 45.7°, compared with the internal (49.5°) and baseline (49.0°) conditions. Therefore, the observed difference in jump distance among conditions can be explained by the external condition producing a more optimal projection angle. The results of this study partially support the constrained action hypothesis.

Adopting an external focus of attention improves sprinting performance in low-skilled sprinters.

For more than 10 years, researchers have investigated how the focusing of conscious attention influences motor skill execution. This line of investigation has consistently demonstrated that directing attention externally rather than internally improves motor skill learning and performance. The purpose of this study was to test the prediction that participants completing a 20-m sprint would run significantly faster when using an external focus of attention rather than an internal or no-focus of attention. Participants were college-aged volunteers (N = 84; 42 women, 42 men; mean age = 20.32, SD = 1.73 years) with no prior sprint training. This study used a counterbalanced within-participant design. Each participant completed 3 days of testing, with each day utilizing a different focus of attention (i.e. internal, external, or control). Running times were collected automatically using infrared timing gates. Data were analyzed using a 1-way repeated measures analysis of variance (ANOVA). The results of the ANOVA revealed a significant main effect for condition, F (1, 83) = 6565.3, p ≤ 0.001. Follow-up analysis indicated that the trials completed in the external focus condition (mean = 3.75 seconds, SD = 0.43) were significantly faster than trials completed in the internal (mean = 3.87 seconds, SD = 0.64) and control conditions (mean = 3.87 seconds, SD = 0.45). The analysis also indicated that the control and internal conditions were not significantly different. The results of this study extend the findings of previous research and demonstrate sprinting performance can be improved by using an external focus of attention.

Increasing the distance of an external focus of attention enhances standing long jump performance.

Numerous studies have demonstrated that using verbal instructions to direct a performers attention externally (i.e., toward the effect of the movement) significantly enhances motor skill performance. Limited research has also demonstrated that increasing the distance of an external focus relative to the body magnifies the effect of an external focus of attention. The purpose of this study was to investigate the effect of increasing the distance of an external focus of attention on standing long jump performance. Using a counterbalanced within-participant design, recreationally trained male subjects (n = 35) performed 2 standing long jumps following 3 different sets of verbal instructions (total of 6 jumps; each separated by 1 minute of seated rest). One set of instructions was designed to focus attention externally near the body (EXN); another set of instructions directed attention externally to a target farther from the body (EXF); the last set of instructions served as a control condition (CON) and did not encourage a specific focus of attention. The results indicated that the EXN and EXF conditions elicited jump distances that were significantly greater than the CON condition. In addition, the subjects in the EXF condition jumped significantly farther than those in the EXN condition. These findings suggest that increasing the distance of an external focus of attention, relative to the body, immediately improves standing long jump performance.

Effect of attentional focus strategies on peak force and performance in the standing long jump.

Significant benefits in standing long jump performance have been demonstrated when subjects were provided verbal instructions that promoted an external focus of attention compared with an internal focus of attention, suggesting differences in ground reaction forces. The purpose of the present study was to evaluate peak force and jump performance between internal and external focus of attention strategies. Untrained subjects were assigned to both experimental conditions in which verbal instructions were provided to promote either an external or internal focus of attention. All subjects completed a total number of 5 standing long jumps. The results of the study demonstrated that the external focus of attention condition elicited significantly greater jump distance (153.6 ± 38.6 cm) than the internal focus of attention condition (139.5 ± 46.7 cm). There were no significant differences observed between conditions in peak force (1429.8 ± 289.1 N and 1453.7 ± 299.7 N, respectively). The results add to the growing body of literature describing the training and learning benefits of an external focus of attention. Practitioners should create standardized verbal instructions using an external focus of attention to maximize standing long jump performance.

Allowing learners to choose: self-controlled practice schedules for learning multiple movement patterns.

For this study, we investigated the effects of self-controlled practice on learning multiple motor skills. Thirty participants were randomly assigned to self-control or yoked conditions. Participants learned a three-keystroke pattern with three different relative time structures. Those in the self-control group chose one of three relative time structures before each of 90 practice trials; yoked participants were not allowed to choose but were yoked to a self-control participant and followed that individual's sequence of practice trials. Results of the 24-hr serial transfer test revealed the self-control group exhibited significantly lower relative timing error, absolute error, and total error than the yoked group. Findings further support the efficacy of self-controlled learning

Contextual interference and augmented feedback: is there an additive effect for motor learning?

Learning to perform a skilled behavior is affected by the context of the practice session and the frequency of augmented feedback. We studied the combined effect of these variables in the acquisition of a ballistic, bi-directional lever movement pattern involving four different target locations as measured by performance in practice, retention, and transfer tests. Augmented feedback was presented in either an every-trial or a faded schedule during random and blocked practice. Consistent with the contextual interference effect, the blocked practice group produced lower errors in acquisition, but the random practice group outperformed the blocked practice group in both retention and transfer. In contrast, faded feedback did not have a beneficial effect on learning and degraded learning when provided during blocked practice. While the results were consistent with previous findings of random and blocked practice, they were not consistent with previous findings of reduced feedback frequencies.

Standing long-jump performance is enhanced when using an external focus of attention.

Several experiments have demonstrated that focusing a performer's attention externally (i.e., on the effects of a movement) rather than internally (i.e., on specific parts of the body) enhances performance when the task requires object manipulation (i.e., throwing a ball to a target). The purpose of this experiment was to investigate if whole-body movements (e.g., standing long jump), without object manipulation, are influenced by an internal or external focus of attention. After participants (n = 120) completed a short warm-up, they were assigned to either an internal (INT) or external (EXT) focus of attention group. All participants completed 5 standing long jumps separated by a 2-minute seated rest. Before each jump, participants in the INT condition were read the following instructions: "When you are attempting to jump as far as possible, I want you to focus your attention on extending your knees as rapidly as possible." Participants in the EXT condition were read the following instructions: "When you are attempting to jump as far as possible, I want you to focus your attention on jumping as far past the start line as possible." An independent samples t-test revealed a significant difference (p = 0.003) in the average distance jumped between the EXT (187.37 +/- 42.66 cm) group and the INT group (177.33 +/- 40.97 cm). The results suggest that providing instructions that focus attention externally enhances standing long-jump performance compared with instructions that focus attention internally. This finding is valuable for strength and conditioning professionals that use jumping tests to evaluate performance.