Theses and Dissertations at Montana State University (MSU)
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Item Influence of anthropometric characteristics on insulin responses to uphill and downhill walking in women(Montana State University - Bozeman, College of Education, Health & Human Development, 2014) Horrigan, Laura Clare; Chairperson, Graduate Committee: Mary P. Miles.; Mary Miles, Karen Brown, Sara Jay, Jay Porter, and Andrea Steward were co-authors of the article, 'Influence of anthropometric characteristics on insulin responses to uphill and downhill walking in women' submitted to the journal 'Medicine and science in sports' which is contained within this thesis.Obesity is associated with insulin resistance as well as several leading causes of preventable death. Exercise is a lifestyle factor that decreases risk of these conditions. The type of exercise performed might play a role in the insulin response to exercise as well as a recommended post-exercise meal. Eccentric exercise is shown to increase insulin resistance while concentric is known to decrease insulin resistance. The purpose of this study was to determine if there are differences in post-exercise insulin levels between eccentric and concentric exercise conditions with a post-exercise meal, and the relationship with waist circumference (WC), a measure of central obesity. Participants were women (n =24), stratified into low (LWC) and high (HWC) waist circumference groups. Participants completed three test conditions: a 45-minute walk at -10% grade at 3.0MPH, a 45-minute walk at +10% grade at a speed that maintained 60% of estimated VO 2max, and a control. A mixed meal was consumed thirty minutes after completion of the test. Finger stick measures of glucose were taken at 0, right before consumption, and then 15, 30, 45, 60, 90, 120 minutes following the meal. Insulin, C-peptide, and glucose were measured pre-test and immediately, 8 hours, and 24 hours after completion of the test. Muscle soreness was measured when blood was collected. The HWC group had higher (p< 0.05) insulin across time points compared to the LWC group in the control and uphill conditions. C-peptide was greater (p<0.05) across time points for the HWC group in the control compared to the LWC group. The HWC group had greater (p<0.05) insulin at 60-minutes in response to the meal during the control condition than the LWC group. The LWC had greater (p<0.05) insulin at 60 minutes in the downhill compared to the control. Muscle soreness was increased (p<0.05) the most in response to the downhill condition. We conclude that waist circumference influenced insulin levels following exercise, where uphill walking improved indices of glycemic control for those of greater waist circumference while downhill walking worsened indices of glycemic control for those of a lower waist circumference.Item Influence of pedometer tilt angle on step counting validity during controlled treadmill walking trials(Montana State University - Bozeman, College of Education, Health & Human Development, 2008) Dock, Melissa; Chairperson, Graduate Committee: Daniel P. HeilPedometers are tools frequently used to monitor walking-related physical activity patterns of overweight and obese populations. However, there is a known association between increasing body mass index (BMI) and decreasing pedometer accuracy. The decrease in pedometer accuracy has been attributed to tilt angle, but the specific tilt angle where pedometers fail to maintain accuracy is unclear. PURPOSE: The purpose of this study was to test two popular pedometer mechanisms, accelerometry- and pendulum-based, to determine the specific tilt angle where the pedometers fail to maintain step counts accurately. METHODS: Twenty subjects (10 men, Mean±SD: 25.4±4.2 yrs, 184.4±5.3 cm, 76.7±6.3 kg; 10 women: 21.6±3 yrs, 166.1±6.3 cm, 56.7±6.7 kg) walked two sets of 21 trials at a combination of treadmill speed (67.0, 80.4, 93.8 m/min) and tilt angle (-30,-20,-10, 0,+10,+20,+30°) while wearing two pedometers; the experimental pedometer attached to a custom-built pedometer gimbal for altering tilt angle, and the control pedometer in a neutral position (±2° of 0°). The pedometers were worn on each hip just anterior to the iliac crest in line with the mid-axillary line of the thigh. The first set of trials tested one pedometer mechanism, while the second set of trials tested the second pedometer mechanism in a counterbalanced order. Mean steps from the experimental pedometer were compared to the control pedometer for each trial (ÄStep=Experimental-Control) using a 3-factor RMANOVA at an alpha level of 0.05. RESULTS: Mean Ästeps for the accelerometry-based pedometer and the pendulum-based pedometer differed significantly (P<0.05) at tilt angles >±10° for treadmill speeds 0° (-30, -20, -10, +10, +20, +30°, respectively). CONCLUSIONS: Increasing tilt angle caused a decrease in pedometer accuracy for both pedometer mechanisms, although the accelerometry-based pedometers were less affected. Negative tilt angles had less effect on pedometer accuracy than positive tilt angles, and the combination of increasing positive tilt angle and slower speeds had the greatest impact on step count accuracy.Item The influence of bout interruptions on measured and predicted physical activity during treadmill walking and running(Montana State University - Bozeman, College of Education, Health & Human Development, 2008) Howe, Stephanie Marie; Chairperson, Graduate Committee: Daniel P. HeilThe importance of daily physical activity (PA) has been established as a means of decreasing risk for chronic diseases. However, the presence of bout interruptions ((BI), defined as a brief pause (< 2 min) PA), can complicate measures of PA. This study was designed to evaluate the influence of different BI rules on PA during treadmill locomotion. Fifteen runners (6 women, 9 men) completed a series of walking (53.6, 107.2 m/min) and running (160.8 m/min) trials while using a metabolic measurement system to measure actual activity energy expenditure (AEEA) and four activity monitors to measure predicted AEE (AEEP). Treadmill speeds were selected to elicit light (L), moderate (M), and vigorous (V) PA intensities. Both AEEA and AEEP, were calculated as the sum within and between the start and end of each defined trial using 3 BI rules: 1) without an allowance for a BI (BI0), 2) or a 1-min BI allowance (BI1), 3) or a 2-min BI allowance (BI2). TA and TP were defined as the time spent at or above a moderate intensity during each PA bout for BI0, BI1, and BI2. Values of AEEA and AEEP for each BI definition and PA intensity were compared within intensities categories using a 2-factor RMANOVA, while data for all three PA intensities were evaluated simultaneously using a RMANOVA. Similarly, values of TA and TP for each BI definition were compared using the same multivariate RMANOVA model. Mean AEEA and AEEP for BI0 were significantly lower than those for BI1 and for BI2 at all PA intensities (p<0.05). When expressed as a percentage, the increase in AEEA and AEEP between BI0 and BI1, or BI1 and BI2, was 0.3-3.9% and between 5.5-11.0% for TA and TP across all intensities. Allowing for 1- or 2-min BIs within a PA bout significantly influences AEE and time during locomotion. These results suggest that rules for the number of BIs allowed should be established since an increase in BIs will cause PA outcome variables to become more dependent on the BIs than the PA itself.Item The influence of backpack chest straps on physiological and performance variables associated with simulated road marching(Montana State University - Bozeman, College of Education, Health & Human Development, 2012) Hollins, Jana Elizabeth; Chairperson, Graduate Committee: Daniel P. Heil; Daniel P. Heil, Mary P. Miles, John G. Seifert, Bryant W. Reinking and Kimberly A. Pribanic were co-authors of the article, 'The influence of backpack chest straps on physiological and performance variables associated with simulated road marching' in the journal 'European journal of applied physiology' which is contained within this thesis.This study compared physiological and performance variables during heavy load carriage while wearing an armored vest under a standard issue military backpack using three different chest strap conditions (no chest strap, NCS; standard chest strap, SCS; modified chest strap, MCS). Twenty subjects, all right-handed shooters, completed 4 laboratory visits. The subjects filled out paperwork, received consumables for the next visit, and performed a handgrip strength test during the first visit. The following 3 visits were testing visits with 2 treadmill walking trials per visit at a fixed speed (80.5 m/min) and grade (2%). Each testing visit corresponded to 1 of 3 conditions (NCS, SCS, or MCS) and included a baseline trial carrying only a training rifle (3.3 kg) followed by a pack trial wearing an armored vest, pack, and rifle (47 kg total). Heart rate (HR, bpm), relative oxygen consumption (RVO 2, ml/kg/min), minute ventilation (V E, L/min), and breathing frequency (BF, breaths/min) were measured. Circumferences (bicep, C B, and forearm, C F, cm) and blood lactate (BL, mmol/L) were assessed once per trial on the non-trigger finger arm, while two-point discrimination (mm) was assessed once on the back of the trigger finger hand. Rating of perceived discomfort (RPD), fingertip oxygen saturation (SpO 2, %), and stride rate (SR, stride/min) were assessed twice each trial. Maximum handgrip strength was assessed in each hand simultaneously (HG right and left, kg) two times per trial. All variables were assessed using multivariate 2-factor RM ANOVA and Scheffe's post hoc test (alpha = 0.05). Baselines for all variables were similar. Pack trial means for HR, RVO 2, V E, and BF were higher than baseline but no difference between strap conditions. Fingertip SpO 2 was lower during pack trials than baseline. There were no differences in V T, BL, or left HG between conditions. NCS resulted in greater C F and C B than baseline with C F also being greater than MCS. Right HG was greater for MCS than baselines and NCS. Right and left HG increased 2 minutes post walking. MCS and SCS provided the least evidence for negatively affecting physiologic and performance outcomes, whereas NCS provides the most evidence for negatively affecting outcomes.