Biomedical subjects

W E Prentice

Publications and source records attributed to W E Prentice.

8 recordsLinked to original sources

PubMed2001

Comparison of ball-and-racquet impact force between two tennis backhand stroke techniqes.

STUDY DESIGN: A mixed design for kinetic comparison of 2 types of one-handed backhand strokes and 2 skill levels in tennis. OBJECTIVES: To develop and evaluate a model to estimate the impact force on the racquet during tennis stroke, and to compare the peak impact force between one-handed backhand stroke with a long backswing and one-handed backhand stroke with a short backswing and between the beginning and advanced players. BACKGROUND: A one-handed backhand stroke is commonly used in tennis and may be associated with many upper extremity over-use injuries. An understanding of kinetics of the backhand stroke is essential for understanding injury mechanisms and prevention. METHODS AND MEASURES: Five male advanced tennis players and 4 male and 1 female beginning tennis players participated. Mean age was 32.2 +/- 7.0 years. Each subject was instructed to use the 2 types of one-handed backhand strokes to hit balls from a tennis ball machine. Three-dimensional coordinates of critical body and racquet landmarks were obtained. A mathematical model was developed to estimate the contact duration and the peak impact force during a stroke. RESULTS: The estimated peak impact forces were reproducible and comparable to those reported in the literature from direct measurements. A one-handed backhand stroke with a short backswing had a significantly shorter contact duration (0.008 +/- 0.003 seconds) and a greater peak resultant impact force (330.0 +/- 140.7) than that with a long backswing (0.016 +/- 0.004 seconds and 180.8 +/- 49.1 N). Skill level did not significantly affect the peak resultant impact force. CONCLUSION: A long backswing in a one-handed backhand stroke may reduce the load on the upper extremity and may assist in reducing the risks of tennis-related upper extremity over-use injuries.

Adult↗

PubMed2000

A comparison of sideline versus clinical cognitive test performance in collegiate athletes.

OBJECTIVE: To test whether performance on 5 cognitive tests administered in a controlled clinical environment differed compared with administration in an uncontrolled sideline environment. Additionally, we investigated the effect of testing environment order on the learning effect for each cognitive test. DESIGN AND SETTING: Athletes were assessed on 2 test occasions (8 +/- 2 days apart), once in a sports medicine research laboratory and once on a lacrosse practice field site. SUBJECTS: A total of 59 Division I collegiate student-athletes participated in this study. MEASUREMENTS: Normative data were collected on 5 cognitive tests (Stroop Test, Trail-Making Test part A, Trail-Making Test part B, Wechsler Digit-Span Forward Test, and Digit-Span Backward Test). RESULTS: An independent-samples t test for environment difference on test day 1 revealed no significant differences between tests performed in the controlled environment and those performed in the uncontrolled environment. A repeated- measures analysis of variance test revealed a significant learning effect for all 5 tests, as subjects tended to improve approximately 11 points on the Stroop Test, 3 seconds on the Trail-Making A Test, 7 seconds on the Trail-Making B Test, and 1 point each on the Wechsler Digit Span Forward and Backward Tests. A paired-samples t test using delta scores (first test minus second test), sorted by order of testing environment, revealed a significant difference for the Stroop Test, but not for the remaining cognitive tests. CONCLUSIONS: There appears to be no difference in cognitive testing performance completed in a controlled clinical environment versus that performed in an uncontrolled sideline environment. This finding suggests that clinicians can administer cognitive tests to athletes with mild head injuries in uncontrolled sideline environments and expect valid results. Thus, clinicians can more thoroughly evaluate mildly head-injured athletes during the most crucial period after injury so that a safe return-to-play decision can be based on quantifiable, objective data.

Journal Article↗

PubMed1999

Collegiate coaches' knowledge of eating disorders.

OBJECTIVE: To assess, through exploratory research, 1) collegiate coaches' knowledge of eating disorders, 2) the confidence of collegiate coaches in their response correctness to questions about eating disorders among athletes, and 3) demographic data related to prior education about eating disorders and the role of the athletic department in providing such educational experiences. DESIGN AND SETTING: We distributed a 2-part questionnaire to 258 NCAA Division I-A coaches from 5 universities selected by sampling convenience. SUBJECTS: One hundred thirty-eight collegiate coaches responded to the questionnaire for a response rate of 53.5%. MEASUREMENTS: Our survey consisted of 30 true-false questions that tested knowledge of eating disorders overall and in 5 domains. These domains included etiology, identifying signs and symptoms, management and treatment, risk factors, and education and prevention of eating disorders. Coaches indicated their level of certainty in their responses by rating their confidence level on a 4-item Likert-type scale. Demographic data focused on educational programs attended by coaches and teams. Descriptive statistics were used to analyze all data. RESULTS: Our results suggest a need for coaches to achieve a greater knowledge of eating disorders in all domains. Evidence showed that educational programs about eating disorders were not often sponsored by the athletic department for coaches or athletes. There seemed to be poor communication between athletic departments and coaches regarding the availability of eating disorder educational resources. CONCLUSIONS: Data suggested coaches could benefit from comprehensive education in all domains of eating disorders; however, further study is needed to validate these findings, to determine the actual effectiveness of education in the prevention of eating disorders, and to differentiate coaches' knowledge specific to sport coached and to coach and team sex.

Journal Article↗

PubMed1999

Proprioception and neuromuscular control of the shoulder after muscle fatigue.

OBJECTIVE: To examine the effects of fatigue on proprioception and neuromuscular control of the shoulder. DESIGN AND SETTING: Subjects were randomly assigned to either an experimental group or control group. Subjects were tested using either the active angle-reproduction or the single- arm dynamic stability test. The subjects were then fatigued using a dynamometer performing continuous, concentric rotation exercises of the shoulder. Once fatigued, the subjects were posttested using the same test. One week later, the subjects returned and were pretested, fatigued, and posttested using the other test. SUBJECTS: Thirty-two college-age (18 to 25 years) subjects (16 males, 16 females) with no history of glenohumeral instability or upper extremity injury volunteered for this study. MEASUREMENTS: Absolute angular error was measured using an electrogoniometer present within the isokinetic dynamometer, while sway velocity was measured using a force-plate system. RESULTS: Repeated-measures analysis of variance revealed a significant difference between the pretest and posttest values for absolute angular error in the experimental group, whereas no significant difference was revealed between pretest and posttest sway velocity for either the control or experimental group. CONCLUSIONS: Fatigue of the internal and external rotators of the shoulder decreased proprioception of the shoulder, while having no significant effect on neuromuscular control.

Journal Article↗

PubMed1998

Establishment of normative data on cognitive tests for comparison with athletes sustaining mild head injury.

OBJECTIVE: To provide normal data for comparison with objective measures of an athlete's cognitive ability after mild head injury (MHI). SUBJECTS: Seventy-two Division I college athletes. DESIGN AND SETTING: Athletes were assessed on three test dates (two days apart) in a sports medicine research laboratory. MEASUREMENTS: Normative data were collected on four cognitive tests (Hopkins Verbal Learning Test, Stroop Test, Reitan Trail-Making Tests, and Wechsler Digit Span Tests). RESULTS: A repeated-measures analysis of variance revealed significant learning effects on all tests except the Hopkins Verbal Learning Test. A high correlation was noted between the Stroop and the Trail-Making Tests. CONCLUSIONS: These normative data can be used as comparisions to provide an objective measure of an athlete's cognitive ability following MHI. By adding this test battery to the athlete's other physical and neurologic tests, the decision to return an athlete to competition after MHI can be made with greater confidence and with less risk of reinjury.

Journal Article↗

PubMed1996

A multipurpose MRI phantom based on a reverse micelle solution.

Many chemical solutions for use in magnetic resonance imaging phantoms have been reported in the literature. Each of these solutions has its application-specific advantages and disadvantages. We propose a single reverse micelle phantom solution, which, although not a universal phantom solution, may find applications in testing of the radio frequency transmit and receive fields of an imaging coil, the homogeneity of the static magnetic field, and the suppression in a fat or water saturation imaging sequence. The solution is thermodynamically stable and biologically inert, it possesses a smaller standing wave artifact than water, and its overall spin lattice relaxation times may be adjusted.

Alkanes↗

PubMed1988

Comparison of three treatment procedures for minimizing ankle sprain swelling.

The purpose of this study was to compare the effects of cold, heat, and contrast bath treatments on the amount of edema in first- and second-degree sprained ankles during the postacute phase of rehabilitation. Thirty subjects with postacute sprained ankles were assigned to a cold (n = 10), heat (n = 10), or contrast bath (n = 10) treatment group. A specially constructed tank was used to take pretreatment and posttreatment volumetric measurements of subjects' sprained ankles. Descriptive statistics, a 3 x 3 two-way analysis of variance for repeated measures, and Tukey's Honestly Significant Difference post hoc test revealed that cold therapy produced the least edema in subjects with sprained ankles (p less than .05). All three treatments (cold, heat, and contrast bath) produced an increase in the amount of edema in the postacute sprained ankles of the subjects. Heat and contrast bath therapy produced almost identical increases in the amount of ankle edema on each of the three days of the study. We concluded that cold therapy is the most appropriate of the three treatments if the therapeutic objective is to minimize edema before rehabilitative exercise during the third, fourth, and fifth days postinjury for first- and second-degree ankle sprains.

Adolescent↗

PubMedDate not supplied

Warming-up and stretching for improved physical performance and prevention of sports-related injuries.

Competitive and recreational athletes typically perform warm-up and stretching activities to prepare for more strenuous exercise. These preliminary activities are used to enhance physical performance and to prevent sports-related injuries. Warm-up techniques are primarily used to increase body temperature and are classified in 3 major categories: (a) passive warm-up - increases temperature by some external means; (b) general warm-up - increases temperature by nonspecific body movements; and (c) specific warm-up - increases temperature using similar body parts that will be used in the subsequent, more strenuous activity. The best of these appears to be specific warm-up because this method provides a rehearsal of the activity or event. The intensity and duration of warm-up must be individualised according to the athlete's physical capabilities and in consideration of environmental factors which may alter the temperature response. The majority of the benefits of warm-up are related to temperature-dependent physiological processes. An elevation in body temperature produces an increase in the dissociation of oxygen from haemoglobin and myoglobin, a lowering of the activation energy rates of metabolic chemical reactions, an increase in muscle blood flow, a reduction in muscle viscosity, an increase in the sensitivity of nerve receptors, and an increase in the speed of nervous impulses. Warm-up also appears to reduce the incidence and likelihood of sports-related musculoskeletal injuries. Improving flexibility through stretching is another important preparatory activity that has been advocated to improve physical performance. Maintaining good flexibility also aids in the prevention of injuries to the musculoskeletal system. Flexibility is defined as the range of motion possible around a specific joint or a series of articulations and is usually classified as either static or dynamic. Static flexibility refers to the degree to which a joint can be passively moved to the end-points in the range of motion. Dynamic flexibility refers to the degree which a joint can be moved as a result of a muscle contraction and may therefore not be a good indicator of stiffness or looseness of a joint. There are 3 basic categories of stretching techniques: (a) ballistic--which makes use of repetitive bouncing movements; (b) static--which stretches the muscle to the point of slight muscle discomfort and is held for an extended period; and (c) proprioceptive neuromuscular facilitation - which uses alternating contractions and stretching of the muscles. Each of these stretching methods is based on the neurophysiological phenomenon involving the stretch reflex.(ABSTRACT TRUNCATED AT 400 WORDS)

Athletic Injuries↗