Notes and double knocks from Arkansas.
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Animal Communication↗
Biomedical subjects
Michael E Powers
Publications and source records attributed to Michael E Powers.
Changes in lower-leg blood flow during warm-, cold-, and contrast-water therapy.
OBJECTIVE: To examine arterial blood flow in the lower leg during warm-, cold-, and contrast-water therapy. DESIGN: A crossover trial with repeated measurements on the dependent variable. SETTING: Hydrotherapy area of a climate-controlled sports medicine clinic. PARTICIPANTS: A volunteer sample of 24 healthy men. INTERVENTION: Four randomly assigned treatments were performed on each subject on consecutive days. MAIN OUTCOME MEASURE: Arterial blood flow (mL per 100mL/min) from baseline measurements were recorded in a 3-minute to 1-minute on-off ratio for 20 minutes by using strain gauge plethysmography. RESULTS: Contrast therapy produced fluctuations in blood flow throughout the 20-minute treatment. Warm-water therapy (40 degrees C) resulted in significant (P < .001) changes in blood flow compared with the control and contrast conditions. Cold-water therapy (13 degrees C) did not produce significantly decreased blood flow as compared with the control condition. CONCLUSIONS: We suggest that further studies involving contrast therapy to the lower leg in injured populations be carried out to determine whether our initial findings are clinically relevant.
Adult↗
Spine-board transfer techniques and the unstable cervical spine.
STUDY DESIGN: A repeated-measures design using a cadaveric model was used in this preliminary investigation on the effectiveness of spine-board transfer techniques. OBJECTIVES: To compare the amount of angulation (flexion-extension) motion that results at the cervical spine during the execution of the log-roll maneuver and the lift-and-slide technique; and to examine how changes to the integrity of the cervical spine impacts the amount of motion generated during the transfer process. SUMMARY OF BACKGROUND DATA: Very little research has been performed to establish the efficacy of spine-board transfer techniques. Early studies have indicated that the log-roll maneuver may not be appropriate for transferring victims with thoracolumbar injuries. Also, there has not been a single study that has reported the impact of transfer techniques on the unstable cervical spine. This lack of data necessitated the present study. METHODS: Four groups (with six participants each) were asked to execute the log-roll maneuver and the lift-and-slide technique on five cadavers. An electromagnetic motion analysis device was used to assess the amount of angulation motion generated at the C5-C6 segment during the execution of these transfer techniques. To examine how changes to the integrity of the cervical spine impacts the amount of motion that is produced during the transfer process, flexion-extension motion was assessed under various conditions: across a stable C5-C6 segment, after the creation of a posterior ligamentous injury, and after a complete segmental injury. RESULTS: No significant differences in angulation motion were noted between transfer techniques. However, significant differences were noted between all three injury conditions. That is, as the severity of the injury increased, the average amount of angulation motion produced at the site of the lesion also increased, regardless of technique. CONCLUSION: The participants of this study were able to restrict flexion-extension motion equally well with thelog-roll maneuver as with the lift-and-slide technique. However, more research is needed to fully ascertain the effectiveness of spine-board transfer techniques.
Aged↗
Cryotherapy does not impair shoulder joint position sense.
OBJECTIVE: To determine the effects of a cryotherapy treatment on shoulder proprioception. DESIGN: Crossover design with repeated measures. SETTING: University athletic training and sports medicine research laboratory. PARTICIPANTS: Thirty healthy subjects (15 women, 15 men). INTERVENTION: A 30-minute cryotherapy treatment. MAIN OUTCOME MEASURES: Joint position sense was measured in the dominant shoulder by using an inclinometer before and after receiving 30 minutes of either no ice or a 1-kg ice bag application. Skin temperature was measured below the tip of the acromion process and recorded every 5 minutes for the entire 30 minutes and immediately after testing. Three different types of error scores were calculated for data analyses and used to determine proprioception. RESULTS: Separate analyses of absolute, constant, and variable error failed to identify changes in shoulder joint proprioception as a function of the cryotherapy application. CONCLUSIONS: Application of an ice bag to the shoulder does not impair joint position sense. The control of proprioception at the shoulder may be more complex than at other joints in the body. Clinical implications may involve modifying rehabilitation considerations when managing shoulder injuries.
Adult↗
Dynamic Stabilization Time After Isokinetic and Functional Fatigue.
OBJECTIVE: To compare the effects of an isokinetic fatigue protocol and a functional fatigue protocol on time to stabilization (TTS), ground reaction force (GRF), and joint kinematics during a jump landing. DESIGN AND SETTING: Subjects were assessed on 2 occasions for TTS, GRF, and joint kinematics immediately before and after completing a fatigue protocol. One week separated the 2 sessions, and the order of fatigue protocols was randomly assigned and counterbalanced. SUBJECTS: Twenty healthy male (n = 8, age = 21.8 +/- 1.4 years, height = 180.6 +/- 7.6 cm, and mass = 74.1 +/- 13.0 kg) and female (n = 12, age = 22.2 +/- 2.1 years, height = 169.3 +/- 9.8 cm, and mass = 62.5 +/- 10.1 kg) subjects volunteered to participate. MEASUREMENTS: Subjects performed 2-legged jumps equivalent to 50% of maximum jump height, followed by a single-leg landing onto the center of a forceplate 70 cm from the starting position. Peak vertical GRF and vertical, medial-lateral, and anterior-posterior TTS were obtained from forceplate recordings. Maximum ankle dorsiflexion, knee-flexion, and knee-valgum angles were determined using 3-dimensional motion analysis. RESULTS: A 2-way analysis of variance with repeated measures revealed no significant differences when comparing TTS, GRF, and joint kinematics after isokinetic and functional fatigue protocols. CONCLUSIONS: No difference was noted between isokinetic and functional fatigue protocols relative to dynamic stability when landing from a jump.
Journal Article↗
An Examination of the Stretch-Shortening Cycle of the Dorsiflexors and Evertors in Uninjured and Functionally Unstable Ankles.
OBJECTIVE: To determine if there were differences in concentric peak torque/body-weight (PT/BW) ratios and concentric time to peak torque (TPT) of the dorsiflexors and evertors in uninjured and functionally unstable ankles using a stretch-shortening cycle (SSC) protocol on an isokinetic dynamometer. DESIGN AND SETTING: We employed a case-control study design to examine the test subjects in a climate-controlled athletic training/sports medicine research laboratory. SUBJECTS: Thirty subjects volunteered to participate in this study, 15 with unilateral functional ankle instability and 15 matched controls. MEASUREMENTS: Participants were assessed isokinetically using an SSC protocol for the dorsiflexors and evertors at 120 and 240 degrees.s(-1), bilaterally. Strength was assessed using PT values normalized for body mass. Concentric TPT measurements were also compared between the groups. RESULTS: No differences in concentric PT/BW ratios or concentric TPT were evident between the groups (P >.05). Additionally, there were no differences in these measurements between the ankles for the same motion and speed between the ankles in the subjects with functional instability. CONCLUSIONS: Using the SSC protocol as a measure of ankle function and the stretch-reflex phenomenon, we found no evidence to support the notion that differences in strength and TPT in the active, conscious state exist between those with functional ankle instability and a group of healthy control subjects.
Journal Article↗
The Safety and Efficacy of Anabolic Steroid Precursors: What is the Scientific Evidence?
OBJECTIVE: Anabolic steroid precursors have gained widespread popularity as ergogenic supplements. Advertisements for these supplements claim that they increase endogenous testosterone production and protein synthesis, resulting in increased lean body mass and strength during training. At this time scientific support is limited, but the potential for serious side effects exists and the popularity of these supplements continues to grow. This review provides rationales for the ergogenic claims regarding steroid precursors and compares claims with data from scientifically controlled investigations. DATA SOURCES: A search of MEDLINE and SPORT Discus from 1960 to 2001 using the key words dehydroepiandrosterone, androstenedione, and androstenediol in combination with testosterone, estrogen, exercise, performance, and side effects. DATA SYNTHESIS: Although fairly new to the athletic community, steroid precursors have been used as ergogenic or anabolic agents for quite some time. Suggested gains in strength and lean body mass are attributed to an increase in the endogenous production of testosterone and enhanced protein synthesis. Most of the scientific data, however, do not support manufacturers' ergogenic claims, and the potential for serious side effects, such as decreased high-density lipoprotein cholesterol and increased estrogen concentrations, has been associated with precursor use. Thus, the safety and efficacy of these supplements must be questioned. CONCLUSIONS/RECOMMENDATIONS: It appears that the risks associated with the use of anabolic steroid precursors outweigh any possible ergogenic benefits. Furthermore, these supplements are banned by most athletic organizations. Thus, it is extremely important that athletic trainers are able to educate athletes on these issues so they can continue to perform at an optimum level in a safe and healthy manner.
Journal Article↗
Assessment of shoulder proprioception in the female softball athlete.
BACKGROUND: There have been reports of overhand throwing athletes having decreased joint position sense in their dominant shoulder as compared with the nondominant shoulder. Very little research, however, exists concerning joint position sense in the female athlete. HYPOTHESIS: Female softball athletes have decreased joint position sense in their dominant shoulder as compared with their nondominant shoulder. STUDY DESIGN: Factorial design with investigation of multiple independent variables. METHODS: Joint position sense was assessed in 50 female softball players and 50 nonthrowing female athletes by using an inclinometer during four glenohumeral joint motions. Both the dominant and nondominant shoulders were assessed and error scores were calculated to describe joint position sense. Data were collected during the course of a fall semester and analyzed by using a mixed model analysis of variance with repeated measures on the dependent variable (error scores). RESULTS: A significant group by movement interaction was observed, with the softball athletes demonstrating significantly greater external rotation error scores than the nonthrowing athletes. CONCLUSION: We failed to reject the null hypothesis. Increased error scores (less joint position sense) were observed in both arms of subjects in the softball group. CLINICAL RELEVANCE: This study suggests that there is decreased shoulder proprioception in asymptomatic female athletes involved in overyhand throwing sports, which may predispose them to injury.
Adult↗