Undergraduate Research

2015 Undergraduate Research Presentations

Dynamic Postural Stability Index: Questionable Reliability in the Absence of Movement Constraint Prior to Landing

Janae L Myers, Isabel E Sim-Campos, & Maren E Iverson

Janae L. Myers, Isabel E. Sim-Campos, Maren E. Iverson
Exercise Science and Sport Study

Poster presented at the American College of Sports Medicine National Conference in San Diego, CA, May 2015

The Dynamic Postural Stability Index (DPSI) is a reliable measure of dynamic postural stability when the jump-landing task constrains the trajectory of the body prior to landing, such as by jumping over a hurdle or jumping to touch an overhead goal. Purpose:  To examine test-retest reliability of the DPSI when body trajectory prior to landing is not constrained by a hurdle or overhead goal. Methods: Forty-eight healthy, physically active participants [24 males (20.6 ± 1.2 years of age, 86.1 ± 11.6kg, and 179.6 ± 8.3cm) and 24 females (19.75 ± 0.8 years of age, 62.8 ± 8.3kg, and 166.3 ± 6.8cm)] performed an anterior leap and a lateral leap from the left (non-dominant) leg, landed on the right (dominant) leg at a distance equivalent to 50% of their maximal leap distance, stabilized their body over the base of support as quickly as possible, and balanced for three seconds. Ground reaction forces in the x, y, and z directions, sampled at 200 Hz, were used to calculate the DPSI. One trial of each leap-landing direction was performed during three test sessions separated by at least 20 hours, but not more than 48 hours. Data from three test sessions were analyzed using an intraclass correlation coefficient (ICC 3,1) formula. Results: Test-retest reliability of the DPSI was judged to be questionable when landing from a forward leap (ICC = .711; 95% CI = .583 - .814) and lateral leap (ICC = .640; 95% CI = .493 - .763). Conclusion: The test-retest reliability of the DPSI when body trajectory prior to landing is not constrained by a hurdle or overhead goal is questionable. Therefore, it is recommended that DPSI testing continue to utilize jump-landing protocols that involve a jump over a hurdle or jump to touch an overhead goal as the test-retest reliability of the DPSI utilizing such protocols has been shown to be moderate to high.


The Effect of Leg Dominance on Dynamic Postural Stability

Sarah A Roehl, Charles G. Broback, & Samuel J. Scoblic

Sarah A. Roehl, Charles G. Broback, Samuel J. Scoblic
Exercise Science and Sport Study, NATS

Poster presented at the 2015 Scholarship and Creativity Day at the College of Saint Benedict, St. Joseph, MN

Research studies utilizing the Dynamic Postural Stability Index (DPSI), a commonly used method to assess an individual's ability to transition efficiently from a dynamic to static state, typically analyze dominant leg (DL) and non-dominant leg (NDL) DPSI values separately. Purpose: To compare DL and NDL DPSI values to determine if there are significant differences in mean scores, which could justify the practice of examining DL and NDL values separately. Methods: Thirty-two healthy and physically active subjects [16 males (19.8 ±1.3 years, 85.6 ±13.0 kg, 180.3 ±8.9 cm) and 16 females (20.2 ±1.0 years, 64.8 ±20.4 kg, 165.2 ±11.2 cm)] completed 20 jumps, landing on one leg on a force plate. Ten jumps were performed in the anterior direction (5 landing on the DL and 5 on the NDL) over a 30 cm hurdle at a distance equal to 40% of body height. Ten jumps were also performed in the lateral direction (5 landing on the DL and 5 on the NDL) over a 15 cm hurdle at a distance equal to 33% of body height. Ground reaction forces in the x, y, and z directions, sampled at 200 Hz, were used to calculate DPSI values in each of the four conditions. Data was analyzed using dependent t-tests. Results: Dependent t-tests revealed no significant differences between mean DPSI values for the DL (0.350 ±0.06; 0.314 ±0.06) compared to the NDL (0.353 ±0.05; 0.312 ±0.05) when landing from an anterior and lateral jump respectively (t(31) = -0.429, p = .671; t(31) = 0.148, p = .883). Additionally, the effect size differences between the DL and NDL were found to be small when landing from the anterior (d = 0.05) and lateral jump (d = 0.03). Conclusion: The non-significant differences in the means and the small effect sizes indicate the DPSI values associated with DL and NDL when landing from an anterior and lateral jump are similar. Therefore, the determination of leg dominance may not be necessary when evaluating dynamic postural stability using the DPSI.


The Relationship between Ground Reaction Force and Softball Pitch Velocity

Melissa A Seldon & Benjamin F Hodapp

Melissa A Seldon, Benjamin F Hodapp
Exercise Science and Sport Study, NATS, Physics

Poster presented at the 2015 Scholarship and Creativity Day at the College of Saint Benedict, St. Joseph, MN

Since the ground is the only external contact for a softball pitcher, ground reaction force (GRF) is theorized to be an important factor in determining softball pitch velocity, yet little research examining this relationship has been published. Purpose: To examine the relationship between the GRF of the stride leg and softball pitch velocity. Methods: Three right hand dominant female Division III intercollegiate softball pitchers (18.3 ±0.6 years; 72.1 ±1.6 kg; 168.0 ±7.9 cm) performed 15 maximal velocity fastball pitches into a net, landing on a force plate with their stride leg, during two separate test sessions (total of 30 pitches per pitcher). Ball velocity was measured to the tenth of one mile per hour using a Stryker radar gun and converted to meters per second. Peak vertical and braking GRFs, sampled at 600 Hz, were normalized to body weight (BW). The slope of the vertical and braking GRFs were calculated by dividing peak GRF by the time from ground contact, defined as the first upward deflection in GRF greater than 5% body weight, to peak force. A Pearson correlation was used to examine the relationship between GRF variables and ball velocity for all 90 pitches. Results: A significant positive correlation was found between ball velocity (23.5 ±0.9 m/sec) and vertical GRF (1.680 ±0.486% BW; r(90) = .696, p < .001), breaking GRF (1.096 ±0.231% BW; r(90) = .854, p < .001), slope of the vertical GRF (31066 ±15952 N/s; r(90) = .294 p = .005), and slope of the braking GRF (12296 ±5457 N/s; r(90) = .535, p < .001) of the stride leg. Conclusion: When a softball is pitched for maximal velocity by Division III softball pitchers using their normal mechanics, there is a positive relationship between GRF variables and ball velocity. Further research is needed to determine whether altering pitching mechanics to accentuate GRF variables will result in greater pitch velocity.


Relationship between BMI, Exercise and Milk Consumption
Morgan N Potter

Morgan N Potter
Exercise Science and Sport Study, Nutrition

Poster presented at the 2015 Scholarship and Creativity Day at the College of Saint Benedict, St. Joseph, MN

Purpose: Research on the relationship between dairy consumption and BMI and percent body fat has been inconsistent. Additionally, there is minimal research on the relationship in American adult populations. Methods: 169 males and 344 females in a small college community were surveyed about their beverage consumption and exercise habits. Participants were 34 +15.6 years old with 45% of the participants between the ages of 18 and 22. On average, the participants consumed 10.6 ±12.6 oz of milk (low fat, reduced fat, and whole milk) per day, with 79.1% of participants drinking only low fat milk. Results: A Pearson correlation revealed an inverse relationship between the consumption of milk and BMI (r= -.104, p=0.019), and a positive relationship between consumption of milk and minutes of exercise per week (r= .179, p<.001). Females also had an inverse relationship between milk consumption and BMI (r= -.150, p= .005). Males had a stronger positive correlation between milk and minutes of exercise per week (r=.219, p=.004) than females (r=.152, p=.005). A sub sample of the participants (40 males, 58 females, 28 +12.3 years, 14.1 +16.5 oz milk per day) volunteered for body composition testing with bioelectrical impedance. In this smaller sample, body fat was significantly and inversely related to milk consumption (r=.-.313, p=.002). Milk consumption was also significantly positively related to physical activity (r=.307, p= .002). Conclusion: Regular exercise and some properties of milk, such as calcium, may play a role in regulation of fat metabolism. Further, individuals who partake in one healthy behavior are more likely to partake in multiple healthy behaviors, such as exercise and healthy eating which can help maintain healthy body consumption.


The Effects of Ankle Bracing on the Performance of the Dynamic Postural Stability Index

Megan E Lawson

Megan E Lawson
Exercise Science and Sport Study

Poster presented at the 2015 Scholarship and Creativity Day at the College of Saint Benedict, St. Joseph, MN

Introduction: Dynamic postural stability is the ability to maintain stability when transitioning from a dynamic to static state. Dynamic postural stability can be measured using the Dynamic Postural Stability Index (DPSI), which is calculated using its directional components Anterior-Posterior Stability Index (APSI), Medial-Lateral Stability Index (MLSI), and Vertical Stability Index (VSI). With evidence that ankle bracing can enhance ankle proprioception, ankle bracing may enhance performance during DPSI testing because dynamic balance relies on proprioception and somatosensory feedback. Purpose: Because prophylactic ankle bracing is common in sport and exercise, it is important to understand how it may impact dynamic postural stability. The purpose of this study is to determine if prophylactic ankle braces have an effect on DPSI values. Methods: Seven males (20.14 ± 0.89 years, 81.44 ± 13.92 kg, 180.96 ± 4.58 cm) and 24 females (20.54 ± 0.72 years, 64.39 ± 8.79 kg, 164.74 ± 6.57 cm) who were physically active and had not worn an ankle brace in the last five years completed the DPSI test protocol. The protocol consisted of three jumps, each landing with the dominant foot on an Accupower force platform. Subjects jumped a distance that was 40% of their height, and over a 12 inch hurdle. One trial was completed without an ankle brace on and another was completed with a brace on the ankle of the dominant leg. Average DPSI, APSI, MLSI, and VSI values for each trial were used for data analysis. Results: A paired samples t-test was used for data analysis. No significant difference between braced (0.086 ± 0.011) and non-braced (0.087 ± 0.015) conditions was found for average APSI values [t(30) = -0.46, p > .05]. No significant difference between braced (0.036 ± 0.014) and non-braced (0.036 ± 0.013) conditions was found for average MLSI values [t(30) = 0.00, p > .05]. No significant difference between braced (0.310 ± 0.0395) and non-braced (0.030 ± 0.043) conditions was found for average VSI values [t(30) = 1.33, p > .05]. A nonsignificant difference between braced (0.325 ± 0.039) and non-braced (0.319 ± 0.044) conditions was found for average DPSI values [t(30) = 1.25, p > .05]. Conclusion: Wearing an ankle brace has no effect on the performance of the DPSI. Ankle braces will neither enhance nor inhibit dynamic postural stability.


The Effect of Static and Dynamic Stretching on Vertical Jump and Agility Performance

David Kahat

David Kahat
Exercise Science and Sport Study

Poster presented at the 2015 Scholarship and Creativity Day at the College of Saint Benedict, St. Joseph, MN

Static and dynamic stretching are often used to help prepare for sport or activity. However, research examining the effect that different stretching protocols have on agility and vertical jump performance remains inconclusive. The purpose of this study was to examine the effect of static and dynamic stretching protocols on countermovement jump (CMJ) and Illinois Agility Test (IAT) times. 9 recreationally active males between ages 18-22 (178.76 SD=2.74 cm, 75.74 SD=16.32 kg, 9.62% SD=4.81% body fat) completed this study. Participants began each session with a 400m jog, then performed one of three stretching protocols. The stretching protocol for each session was chosen in a randomized order. Following the completion of the stretching protocol, subjects completed three CMJs, then completed the IAT 3 times. The best of the three trials for CMJ and IAT was used for data analysis. Mean IAT times were 16.72s (SD=1.28), 16.53s (SD=.95), and 16.43s (SD=.88) for the control, static, and dynamic stretching protocols respectively. CMJ heights were 65.12cm (SD=16.32), 64.56cm (SD=7.74), and 65.02cm (SD=8.71) for the control, static, and dynamic stretching protocols respectively. A one way repeated measures ANOVA was used to test the data for significance. No significant differences were found within subjects for IAT (F (2,16) = 2.31, p = .13) or CMJ (F (2,16) = .14, p = .875). The lack of difference between treatments may have been due to too much time immediately following protocols, therefore negating any benefit that would result from the stretching protocol. While no significant differences were found between IAT and CMJ performance with different stretching protocols, this does not necessarily mean stretching protocols are equally advantageous for jump and agility performance. Further research is needed to understand the benefits of different stretching protocols on agility and vertical jump performance. Research examining power and agility performance immediately following stretching protocols, or stretching protocols with stretches held for longer durations may yield different results.


Characterizing Weightlifting Participation in College Aged Women

Margaret M Paul

Margaret M Paul
Communication, Exercise Science and Sport Study, Gender & Women's Studies

Poster presented at the 2015 Scholarship and Creativity Day at the College of Saint Benedict, St. Joseph, MN

Weight bearing activity is an important component of overall health. According to the CDC (2007), only one third of women aged 18-24 obtain sufficient levels of physical activity, making them a particular concern. Many women may lack knowledge of proper weightlifting techniques, have incorrect information about weightlifting or have time constraints that prevent them from participating. PURPOSE: To determine if and why college aged women participate in or withhold from weight training methods. METHODS: 249 college-aged women were surveyed and 12 of those women participated in small focus groups. RESULTS: 57.8% of women were in the "normal" BMI category. Survey participants indicated that they were mostly "healthy" or "very healthy" (82.4%). Despite being an active sample, (88% indicated that they were either "active" or "very active"), less than half of respondents indicated that they participated in weightlifting either "often" or "very often". Additionally, 27.7% of women agreed, strongly agreed or were neutral when answering the statement, weightlifting is unnecessary when I am being physically active. Women reported the top three factors that motivated them to participate in weightlifting were to stay in shape, it made them feel good and it improved how they looked/the way they felt about their body. For women who faced obstacles when trying to include weightlifting into their workouts, time constraints seemed to be the largest barrier. It is possible that women place a great deal of emphasis on aerobic exercise and thus, lack time to add weightlifting to their exercise routine. CONCLUSION: Though the reported activity levels in this sample were encouraging, an effort should still be made to address misconceptions and a lack of education surrounding weightlifting, especially in college aged women. More health and fitness education may help college students shift their attitudes and feel more empowered about adding weightlifting to their exercise routines. Campus-wide campaigns with high visibility tactics that deliver more than one component, such as educating and programming, have the potential for causing positive behavior change. Efforts such as these could be useful strategies in increasing the levels of participation of women in weightlifting on college campuses.