Biomedical subjects

Kathleen A Swanik

Publications and source records attributed to Kathleen A Swanik.

6 recordsLinked to original sources

PubMed2006

Gender comparisons of dynamic restraint and motor skill in children.

OBJECTIVES: To assess differences in neuromuscular dynamic restraint between high-skilled and low-skilled prepubescent girls and boys. To determine the contribution of sport experience and physical characteristics to motor skill. SUBJECTS: Nineteen girls and 17 boys (8.89-9.40 y) participated. INTERVENTION: Isometric hamstring and quadriceps muscle strength was assessed. Subjects performed 3 landing trials for measurement of preparatory EMG and vertical leg stiffness. Motor skill was assessed through analysis of 12 fundamental tasks. Sport experience was reported as hours per week and total years in organized and nonorganized activity. OUTCOME MEASURES: Dynamic restraint variables of isometric strength, preparatory EMG activity, and vertical leg stiffness were measured between groups. The contributions of time in sport, type of sport, and physical characteristics on skill were analyzed. RESULTS: No significant gender or skill differences were found in quadriceps strength (P = 0.73), hamstring strength (P = 0.96), hamstring-to-quadriceps ratio (P = 0.71), or vertical leg stiffness (P = 0.38). Low-skilled children exhibited significantly greater (47.8%) preparatory hamstring-quadriceps coactivation than high-skilled subjects (P = 0.03). Participation in organized and nonorganized sport accounted for 29% of the variance in motor skill. CONCLUSIONS: Neuromuscular differences between genders were not observed, but dynamic restraint EMG measures differed between skill levels. The factors predisposing females to noncontact injuries may develop prepuberty to postpuberty from a combination of variables. Greater coactivation in the low-skilled group appears consistent with immature feedforward neuromuscular control strategies. These unrefined motor skills are less economical, may compromise dynamic restraint, and appear partially determined by sport experience.

Athletic Injuries↗

PubMed2005

Gender differences in head-neck segment dynamic stabilization during head acceleration.

PURPOSE: Recent epidemiological research has revealed that gender differences exist in concussion incidence but no study has investigated why females may be at greater risk of concussion. Our purpose was to determine whether gender differences existed in head-neck segment kinematic and neuromuscular control variables responses to an external force application with and without neck muscle preactivation. METHODS: Forty (20 females and 20 males) physically active volunteers participated in the study. The independent variables were gender, force application (known vs unknown), and force direction (forced flexion vs forced extension). The dependent variables were kinematic and EMG variables, head-neck segment stiffness, and head-neck segment flexor and extensor isometric strength. Statistical analyses consisted of multiple multivariate and univariate analyses of variance, follow-up univariate analyses of variance, and t-tests (P < or = 0.05). RESULTS: Gender differences existed in head-neck segment dynamic stabilization during head angular acceleration. Females exhibited significantly greater head-neck segment peak angular acceleration (50%) and displacement (39%) than males despite initiating muscle activity significantly earlier (SCM only) and using a greater percentage of their maximum head-neck segment muscle activity (79% peak activity and 117% muscle activity area). The head-neck segment angular acceleration differences may be because females exhibited significantly less isometric strength (49%), neck girth (30%), and head mass (43%), resulting in lower levels of head-neck segment stiffness (29%). CONCLUSION: For our subject demographic, the results revealed gender differences in head-neck segment dynamic stabilization during head acceleration in response to an external force application. Females exhibited significantly greater head-neck segment peak angular acceleration and displacement than males despite initiating muscle activity earlier (SCM only) and using a greater percentage of their maximum head-neck segment muscle activity.

Acceleration↗

PubMed2005

Joint stiffness and pain in individuals with patellofemoral syndrome.

STUDY DESIGN: Pretest-posttest matched control group design. OBJECTIVES: To measure passive knee joint stiffness and pain in participants with and without patellofemoral pain syndrome (PFPS) and to determine the relationship between mechanical knee joint stiffness, self-reported stiffness, and pain. BACKGROUND: Patients with PFPS complain of knee joint stiffness and pain, but no research has quantified both of these characteristics in this population. METHODS AND MEASURES: Twenty-eight individuals (14 with PFPS [mean age +/- SD, 25.5 +/- 4.8 years] and 14 healthy controls [mean age +/- SD, 22.8 +/- 5.4 years]) volunteered for this study. Mechanical passive knee joint stiffness was calculated using the damped natural frequency of oscillation of the lower leg while sitting. Mechanical stiffness was compared to self-reports of knee stiffness and pain. All measurements were recorded presitting and after 20 minutes of sitting. RESULTS: Sitting for 20 minutes did not induce significant changes in mechanical knee joint stiffness. However, participants with PFPS reported significantly greater (P<.01) knee stiffness after sitting for 20 minutes. A significant correlation (r = 0.70, P<.01) was found between self-reported stiffness and pain in participants with PFPS; however, no significant relationship was observed between mechanical and self-reported knee joint stiffness. CONCLUSIONS: Despite frequent complaints of joint stiffness, the knees of individuals with PFPS do not appear physiologically stiffer than those of control subjects. Individuals with PFPS perceive increased knee stiffness after sitting, but may misinterpret the sensation of pain as joint stiffness.

Adult↗

PubMed2004

Neuromuscular dynamic restraint in women with anterior cruciate ligament injuries.

The purpose of this study was to identify neuromuscular characteristics related to dynamic restraint in the knee. Observing compensatory changes to these characteristics in women with anterior cruciate ligament injuries provides important information for understanding functional knee stability, injury prevention, and performance. Twelve female subjects with anterior cruciate ligament injuries and 17 female control subjects participated in this study to assess electromyographic activity during landing from a hop and knee perturbation; hamstring muscle stiffness and flexibility; and isokinetic strength. Females with anterior cruciate ligament deficiencies had significantly increased preparatory muscle activity in the lateral hamstring before landing, but no differences in reactive muscle activity during landing or reflex latency after joint perturbation. Females with anterior cruciate ligament deficiencies had significantly less hamstring muscle stiffness and flexibility, but also had greater peak torque and torque development for knee flexion. Lower Lysholm scores were observed in females with anterior cruciate ligament deficiencies but no difference was found in functional performance of the single leg hop test. These neuromuscular characteristics provide a foundation for future research investigating injury prevention and rehabilitation techniques that maximize dynamic restraint through stiffness regulation and the timing of specific muscle activation strategies.

Adult↗

PubMedDate not supplied

The effects of shoulder plyometric training on proprioception and selected muscle performance characteristics.

The purpose of this study was to determine the effect of plyometric training of the shoulder internal rotators on proprioception, kinesthesia, and selected muscle performance characteristics in female swimmers. Twenty-four female division I swimmers were evaluated before and after a 6-week plyometric training program. Proprioception and kinesthesia were assessed for internal and external rotation at 0 degrees, 75 degrees, and 90% of the subject's maximum external rotation. The Biodex II was used to assess strength characteristics at 60 degrees /s, 240 degrees /s, and 450 degrees /s. Plyometric training sessions (2 times/week) involved 3 sets of 15 repetitions with a trampoline, weighted balls, and elastic tubing. A 2-way analysis of variance revealed significant improvement (P <.05) in proprioception at 0 degrees moving into external rotation, as well as 75 degrees and 90% moving into both internal and external rotation. Kinesthesia demonstrated significant improvement for all test conditions after plyometric training. Significant gains in selected muscle performance characteristics included time to peak torque (60 degrees /s and 240 degrees /s), amortization time (450 degrees /s), and torque decrement (240 degrees /s). This study suggests that plyometric activities may facilitate neural adaptations that enhance proprioception, kinesthesia, and muscle performance characteristics. Significant neuromuscular benefits may be attained if they are implemented earlier into shoulder rehabilitation programs.

Adult↗

PubMedDate not supplied

Resistance training and head-neck segment dynamic stabilization in male and female collegiate soccer players.

CONTEXT: Cervical resistance training has been purported to aid in reducing the severity of brain injuries in athletes. OBJECTIVE: To determine the effect of an 8-week resistance-training program on head-neck segment dynamic stabilization in male and female collegiate soccer players. DESIGN: Pretest and posttest control group design. SETTING: University research laboratory and fitness center. PATIENTS OR OTHER PARTICIPANTS: Thirty-six National Collegiate Athletic Association Division I collegiate soccer players (17 men, 19 women). INTERVENTION(S): The resistance training group underwent an 8-week cervical resistance training program that consisted of 3 sets of 10 repetitions of neck flexion and extension at 55% to 70% of their 10-repetition maximum 2 times a week. Participants in the control group performed no cervical resistance exercises. MAIN OUTCOME MEASURE(S): Head-neck segment kinematics and stiffness, electromyographic activity of the upper trapezius and sternocleidomastoid muscles during force application to the head, and neck flexor and extensor isometric strength. RESULTS: No kinematic, electromyographic, or stiffness training effects were seen. The posttest resistance training group isometric neck flexor strength was 15% greater than the pretest measurement. Isometric neck extensor strength in the female resistance training group was 22.5% greater at the posttest than at the pretest. Women's neck girth increased 3.4% over time regardless of training group level. Women exhibited 7% less head-neck segment length and 26% less head-neck segment mass than men. CONCLUSIONS: Despite increases in isometric strength and girth, the 8-week isotonic cervical resistance training did not enhance head-neck segment dynamic stabilization during force application in collegiate soccer players. Future researchers should examine the effect of head-neck segment training protocols that include traditional and neuromuscular activities (eg, plyometrics) with the focus of reducing head acceleration on force application.

Journal Article↗