Postural regulation is an important part of a variety of motor tasks, including quiet standing and locomotion. Muscle length feedback, both the autogenic length feedback arising from a muscle's own spindles, and heterogenic length feedback, arising from its agonists and antagonists, is a strong modulator of muscle force and well suited to postural maintenance. The effects of this reflex feedback on 3-D force generation and limb mechanics are not known. In this paper, we present a mechanical model for relating 3-D changes in cat hindlimb posture to changes in muscle lengths. These changes in muscle length are used to estimate changes in both intrinsic muscle force generation and muscle activation by length feedback pathways. Few muscles are found to have directly agonist mechanical actions, and most differ by more than 20°. Endpoint force fields are largely uniform across the space investigated. Both autogenic and heterogenic feedback contribute to whole limb resistance to perturbation, autogenic pathways being most dramatic. Length feedback strongly reinforced a restoring force in response to end-point displacement.
Thomas J. Burkholder and T. Richard Nichols
Deborah L. Feltz and Camala A. Riessinger
An experiment was conducted to investigate the relative merits of in vivo emotive imagery and performance feedback in enhancing self-efficacy beliefs and performance on a competitive muscular endurance task. College males (n=60) and females (n=60) were randomly assigned to one of three conditions: mastery imagery plus feedback, feedback alone, or control condition. Subjects in the imagery-plus-feedback condition were told that one of the pair (always the subject) would receive imagery exposure while the other (always the confederate) would wait outside. Subjects performed two trials against the confederate, who always won by 10 seconds. A Group x Trials interaction for self-efficacy revealed a significant increase for the imagery group after brief exposure. Also, imagery subjects had significantly higher efficacy scores than feedback alone or control subjects after each performance trial. A Group x Trials interaction for performance indicated that imagery subjects initially had significantly longer performance times than did feedback alone or control subjects. Performance feedback alone did not influence efficacy beliefs or performance.
Veerle Puttemans, Sophie Vangheluwe, Nicole Wenderoth and Stephan P. Swinnen
When performing movements with different spatial trajectories in both upper limbs simultaneously, patterns of interference emerge that can be overcome with practice. Even though studies on the role of augmented feedback in motor learning have been abundant, it still remains to be discovered how overcoming such specific patterns of spatial interference can be optimized by instructional intervention. In the present study, one group acquired a bimanual movement with normal vision, whereas a second group received augmented feedback of the obtained trajectories on a computer screen in real time. Findings revealed that, relative to normal vision, the augmented feedback hampered skill learning and transfer to different environmental conditions. These observations are discussed in view of the benefits and pitfalls of augmented feedback in relation to task context and instructional condition.
Andrea Hazen, Carolyn Johnstone, Garry L. Martin and Suja Srikameswaran
A videotaping feedback package was developed for improving skills of youth competitive swimmers. Experiment 1 examined the videotaping package for improving freestyle and backstroke racing turns of young competitive swimmers. Positive results were obtained in a multiple-baseline design across subjects. Experiment 2 compared the videotaping feedback package to a group videotaping procedure (that the coach had been using at the time of this research) for improving freestyle swimming strokes of young competitive swimmers. The videotaping feedback package was effective whereas the group videotaping procedure had little or no effect. For most subjects in the two studies, improvements were maintained with minimal prompting and feedback under normal practice conditions. Suggestions for future research are discussed.
Alexander T. Latinjak, Miguel Torregrosa and Jordi Renom
The main purpose of this study was to examine the efficacy of a strategy that combined self talk and performance feedback. Therefore, three groups of adult tennis players performed a forehand groundstroke task. The first group (n = 16) applied an instructional self talk and self feedback combination, the second (n = 16) used regular instructional self talk, and the third (n = 16) performed without any specific aid. The hypothesis was that the performance and concentration scores of both self talk groups would improve from the pretest to the posttest, while the scores from the control group would remain unchanged. The analysis of variance with repeated measures confirmed this hypothesis. Further, the players who used self feedback perceived the effectiveness of their intervention to be significantly higher compared with the other intervention group. Overall, the combination of self talk and feedback seems to be an alternative to the original instructional self talk intervention.
John B. Cronin, Eadric Bressel and Loren Finn
Frequency and magnitude of ground reaction forces (GRF) have been implicated in causing injuries such as “jumpers knee.”
To investigate whether a single session of augmented feedback concerning landing technique would decrease GRF.
Pretest posttest experimental design.
University biomechanics laboratory.
Fifteen female Division 1 intercollegiate volleyball players.
Participants were required to land on a force platform after spiking a volleyball from a four-step approach before and after an intervention involving visual and aural augmented feedback on correct jumping and landing technique.
Main Outcome Measures:
Mediolateral (ML), anterioposterior (AP), and vertical (V) GRF normalized to body weight (BW).
Augmented feedback was found to significantly (P = 0.01) decrease VGRF by 23.6% but not ML (25%, P = 0.16) and AP (4.9%, P = 0.40) peak GRF.
A single session of augmented feedback may be effective in reducing VGRF in collegiate athletes.
Zoe Butcher, Stuart Fairclough, Gareth Stratton and David Richardson
This study examined whether feedback or feedback plus physical activity information could increase the number of pedometer steps taken during 1 school week. One hundred seventy-seven students (mean age 9.124 ± 1.11 years) in three elementary schools participated. Schools were randomly assigned to control (CON), feedback (FB), or feedback plus information (FB+I) groups. Children wore pedometers during school time for 5 consecutive weekdays. The total steps of the groups were recorded at the end of each school day, with students in the FB and FB+I groups free to view their step counts. In addition, the FB+I group received information and ideas about how they could increase their daily steps. The CON group received no step-count feedback or information. Students in the FB+I group achieved significantly more steps per minute (17.17 ± 4.87) than those in the FB (13.77 ± 4.06, p = 0.003) and CON (12.41 ± 3.12, p = 0.0001) groups. Information, as well as step-count feedback, increased elementary students’ school-based physical activity (number of steps) in the short term. A longer intervention period is necessary to assess the sustained impact of this type of approach.
Howard K. Hall, Mobert S. Weinberg and Allen Jackson
The purpose of the present investigation was twofold: first, to examine the relationship between goal difficulty, goal specificity, and endurance performance in a physical activity setting, and second, to determine the relationship between different types of information feedback, goals, and performance. Subjects (N = 94) performed on a hand dynamometer endurance task, being asked to hold a one-third maximum contraction for as long as possible. The subjects were randomly assigned to one of the following goal-setting conditions: (a) Do your best, (b) improve by 40 s, or (c) improve by 70 s. They were provided with either concurrent or terminal feedback in a 2 x 3 x 2 (feedback x goals x trials) design. Performance results indicated a significant goals-by-trials interaction with the 40- and 70-s goal groups exhibiting significantly more improvement than the "do your best" group. No significant performance differences were found between the two feedback groups. However, significant differences in the performance-associated cognitions of the feedback groups indicated a preference for concurrent feedback as an adjunct to goals. Results are discussed in terms of Locke's goal-setting theory as well as some recent field research investigating the goal-setting performance relationship in physical education settings.
Benjamin W. Stroube, Gregory D. Myer, Jensen L. Brent, Kevin R. Ford, Robert S. Heidt Jr. and Timothy E. Hewett
Anterior cruciate ligament (ACL) injuries are prevalent in female athletes. Specific factors have possible links to increasing a female athlete’s chances of suffering an ACL injury. However, it is unclear if augmented feedback may be able to decrease possible risk factors.
To compare the effects of task-specific feedback on a repeated tuck-jump maneuver.
Double-blind randomized controlled trial.
Sports-medicine biodynamics center.
37 female subjects (14.7 ± 1.5 y, 160.9 ± 6.8 cm, 54.5 ± 7.2 kg).
All athletes received standard off-season training consisting of strength training, plyometrics, and conditioning. They were also videotaped during each session while running on a treadmill at a standardized speed (8 miles/h) and while performing a repeated tuck-jump maneuver for 10 s. The augmented feedback group (AF) received feedback on deficiencies present in a 10-s tuck jump, while the control group (CTRL) received feedback on 10-s treadmill running.
Main Outcome Measures:
Outcome measurements of tuck-jump deficits were scored by a blinded rater to determine the effects of group (CTRL vs AF) and time (pre- vs posttesting) on changes in measured deficits.
A significant interaction of time by group was noted with the task-specific feedback training (P = .03). The AF group reduced deficits measured during the tuck-jump assessment by 23.6%, while the CTRL training reduced deficits by 10.6%.
The results of the current study indicate that task-specific feedback is effective for reducing biomechanical risk factors associated with ACL injury. The data also indicate that specific components of the tuck-jump assessment are potentially more modifiable than others.
Shamsi S. Monfared, Gershon Tenenbaum, Jonathan R. Folstein and K. Anders Ericsson
Feedback is critical for multiple aspects of performance in sports and everyday tasks. One fundamental role of feedback is to allow anticipation of the outcome of an action. Anticipation requires athletes to pay attention to internal (e.g., sensory information) or external (e.g., opponent’s body