Effects Of Local Muscle Fatigue On Proprioception And Motor Learning

ABSTRACT EFFECTS OF LOCAL MUSCLE FATIGUE ON PROPRIOCEPTION AND MOTOR LEARNING by GOWTAMI DATLA May 2016 Advisor: Dr. Qin Lai Major: Kinesiology and Exercise Science Degree: Masters of Education Background: Muscle fatigue is an exercise induced decline in the ability of muscles to produce force or power. Recent studies showed that decline in proprioception due to fatigue lead to an increasing risk of falls and injury. However, it was unknown whether fatigue-induced proprioception decrease affects skill acquisition and memory consolidation. Purpose: The aim of the study was to investigate the effects of local muscle fatigue on perceptual motor learning in arm positioning task and to compare surface EMG activities in the fatigue and non-fatigue muscle conditions. Two experiments were used to investigate the purpose. In Experiment 1, Methods: 24 healthy young adults (Age: 20-40) were randomly and equally assigned into either control or experiment group. An informed consent was signed prior to the study. Both the groups performed the same task but the experiment group underwent a fatigue protocol (biceps curls with weight of 80% voluntary contraction until fatigue) during the acquisition phase. The task was to place the left forearm on a kinestheiometer and moved the handle to 30, 45, 60 degrees by flexion. All the participants performed 1 block of pre-test, 5 blocks of acquisition phase, 1 block of post-immediate test during the first visit. A delayed retention and bilateral transfer tests were administered 48 hrs after the first visit. Each block had 12 trials. Throughout the task participants were blind folded and were given verbal feedback during the acquisition only. Results: A 2 X 5 (Group vs. Block) ANOVA with repeated measure on Block for acquisition demonstrated both groups decreased total movement error (E) with practice, F (4, 88) = 10.46, p\u3c.01. A main effect of group was detected, F (1, 22) = 4.91, p\u3c.05. Duncan’s MRT indicated fatigue group (M=5.73) produced more E relative to the controlled (M=4.93). A separated ANOVA for retention, and transfer tests also detected a main effect of group, F (1, 22) = 10.19, p\u3c.01 for total error. DMRT revealed that fatigue group (M=8.08) produced more variable error than control group (M=5.41). The analysis did not detect difference between retention and transfer [F (1, 22) = 0.26, P\u3e 0.05] or interaction [F (1, 22) = 0.00, P\u3e 0.05]. In Experiment 2, Methods: 12 healthy individuals (age 20-40) participated in the experiment that consisted of 6 blocks with 12 trials each. All the participants performed 6 blocks of task and fatigue protocol before every other block. After fatigue protocol participants were made to perform the task immediately without rest but were given 2 minutes rest after each block. Results: One way ANOVA with repeated measure on condition showed a main effect of fatigue for the EMG frequency, F (1, 22) = 7, P\u3c.05. Where fatigue condition was greater than non-fatigue. The main effect was also detected for the integral EMG (amplitude), F (1, 12) = 6.14, P\u3c .05, where non fatigue was greater than fatigue. Conclusion: Both the control and experiment group exhibited perceptual motor learning with practice. The fatigue group showed a greater error than the control group in acquisition, retention and transfer. The surface EMG showed increased frequency and decreased integral (amplitude) in the fatigued muscle when compared to non-fatigue condition. In summary, local muscle fatigue had negative effects on perceptual motor acquisition and memory consolidation by degrading proprioception and efficiency on the muscles

Examining Mediators to Physical Activity as a Link to Interventional Efforts Aimed at Increasing Activity Levels and Improving Physical Functioning in Older Adults

The number of older adults living in the United States is growing at an increasingly rapid rate, and is host to a high prevalence of chronic diseases and physical impairments. Physical activity and exercise have been shown to be beneficial in impacting such conditions, yet the majority of older adults remain inactive. The purpose of this dissertation was to employ a sequence of studies to investigate mediators to physical activity, leading to an intervention to increase activity and promote health. The purpose of Project VOICE was to examine whether awareness and utilization of community resources to promote physical activity and exercise differed by residential spatial tiers of increasing distance from the resources. Results showed that approximately 50% of the sample was aware of the resources, yet utilization rates fluctuated around a paltry 3% (there were no differences across spatial tiers). The most notable barriers that influenced participation were interest in resources available, current health status, and transportation to and from community resources. Efforts are warranted to increase interest in using such resources, and/or developing interventions that overcome noted barriers. Extending upon the results of Project VOICE, Project PACE employed a home-based intervention aimed at increasing physical activity and engagement in exercise, to improve physical functioning levels in community-dwelling older adults. An enhanced physical activity prescription of daily step goals (increasing 10% weekly) and resistance band exercises was provided for the intervention group, compared to a standard of care group who were prescribed 10,000 steps/day. The intervention group significantly increased the amount of steps taken daily, compared to the standard of care group, and improved physical functioning. These results were enhanced within those who had greater compliance to the prescribed intervention, however, this included only 25% of the total group sample. Future studies should include a larger sample size and a longer study design with follow up measurements, focusing on improving intervention adherence. Considering the low utilization of community resources for physical activity and exercise, a low-cost, home-based intervention was successful in increasing physical activity and improving physical functioning, demonstrating the potential and advantages of programs easily translatable into everyday life

Evaluation of Physical Activity Participation, Self-Efficacy and Outcome Expectancy for Employees Participating in Exercise Is Medicine® On Campus Program

Exercise Is Medicine® On Campus (EIM-OC) is a worldwide initiative from the American College of Sports Medicine (ACSM) to promote physical activity (PA) at universities. California State University, Monterey Bay (CSUMB) implemented this initiative in Fall 2019 with offerings to students and employees. For employees, an “Introduction to Resistance Training Class” was offered. Participants attended classes two times per week, with the sessions lasting approximately fifty minutes. The purpose of this study was to evaluate the EIM-OC employee Introduction to Resistance Training class for its effectiveness on increasing PA, self-efficacy, and outcome expectancy. The research design was pre-post, with participants completing online questionnaires before and after the course. The Godin Leisure Time Physical Activity Questionnaire (LTPQ), Resistance Training Self-Efficacy and Outcome Expectancy Questionnaire, and Self-Efficacy and the Maintenance of Exercise Participation in Older Adults Questionnaire were included. The training class had a total of 14 female participants, 12 of which completed the pre- and postquestionnaires. There was a significant increase (t=-3.2, df=11, p=.004) in resistance training self-efficacy score following the course (M=3.52±1.03 versus M=4.31±.56). Resistance training outcome expectancy score was also statistically significant (t=- 2.54, df=11, p=.01) following the course (M=4.48±.53 versus M=4.71±.37). There were increases in strenuous exercise days, physical activity scores, and future resistance training self-efficacy, although they were not statistically significant. The results of this study indicate that employee exercise classes, as part of the EIM-OC initiative, can be effective in increasing resistance training self-efficacy, and outcome expectancy. These indicators are important for individuals to maintain lifelong PA therefore future programming and research on EIM-OC should continue

Undergraduate Exercise Physiology Major Changes, Dept KSSPE

Proposed changes in the undergraduate exercise physiology major in the Department of Kinesiology, Sport Studies, and Physical Education include: 1) name change to Exercise Science 2) an increase in the internship from 3 to 6 credits, 3) a new program-specific nutrition course which replaces the generic nutrition course in the current curriculum, 4)changes to the name and number of a currently required course, 5) addition of a new course in exercise testing and prescription, and 6) addition of an on-campus practicum class

The Validity & Reliability of the Repetitions in Reserve Based Rating of Perceived Exertion Scale in Single Joint Exercise

Introduction: Intentional regulation and individualization of resistance training schemes are imperative when structuring a resistance training program. Optimal adaptation cannot be expected without proper manipulation of training variables such as load and volume. Load is traditionally prescribed by testing a given exercise’s repetition maximum and basing intensity from that load. This method of intensity regulation may be limited, considering it fails to recognize the day-to-day undulation of individual performance which can be impacted by several variables. A flexible method of regulating load and volume would be of use for those undergoing a resistance training program. The repetitions in reserve-based rating of perceived exertion (RIR-RPE) scale is a perception-based tool used to autoregulate the intensity of a lift. RIR-RPE allows for the user to govern programming variables such as load and volume on a day-to-day basis. Purpose: The aim of this study was to assess the validity and reliability of the RIR-RPE scale in single joint resistance exercise. Methods: 12 participants (7 male and 5 female) (age: 20.42 ± 1.98 years, training age: 5.83 ± 3.19 years, weight: 76.59 ± 16.74 kg, height: 1.72 ± 0.09 m) volunteered for this three-session study, each separated by a minimum of 48 hours. Session one included anthropometric assessments and 8RM tests for unilateral bicep curl and leg extension exercises. Participants were also familiarized to the RIR-RPE scale in session one. In session two, participants completed three sets at 70, 75, and 80% of predicted one repetition maximum for nine, seven, and five repetitions, respectively. After completing the assigned number of repetitions, participants were asked to pause and indicate a value on the RIRRPE scale before continuing the set to technical failure. Velocity was measured on the iv repetition RIR-RPE was gathered and the final repetition before failure. Session three was the same as session two to assess reliability. Participants were randomized and blinded to the order in which they were exposed to the intensities. Results: Participants tended to underpredict RIR by approximately one repetition (1.02 ± 0.32 ) on average. Participants became more accurate in their predictions in session two (0.93 ± 0.44) compared to session one (2.78 ± 0.73). Calculations of intraclass correlation coefficients for absolute agreement revealed moderate to strong agreement between estimated- and actual-RIR in the bicep curl with a range of (0.51 – 0.91) and weak to moderate agreement in the leg extension with a range of (0.183 – 0.66). Reliability was low to moderate in the bicep curl with a range of (0.26 – 0.64) and low in the leg extension exercise with a range of (0 – 0.102). A negative relationship between RIR-RPE and velocity was at 70% (r = - 0.62, p = 0.023), 75% ( r = - 0.86, p = 0.00017), 80% (r = - 0.42, p = 0.15) in the bicep curl and at 70% (r = - 0.8, p = 0.0016), 75% (r = - 0.77, p = 0.0021), 80% (r = - 0.67, p = 0.12) in the leg extension. Conclusions: The RIR-RPE scale is not perfectly accurate. The meaningfulness of an underprediction on one RIR has yet to be investigated. Individuals using the RIR-RPE scale tend to get more accurate over with experience. The RIR-RPE scale may not be reliable in single joint exercise until the individual using the scale has adequate experience. Practical Applications: Athletes and practitioners may consider using the RIR-RPE scale as a flexible way of autoregulating resistance training variables

Effect of altering range of motion on muscle activation patterns when using the MuJo™ Shoulder Machines

Resistance equipment is often restricted to a single plane of movement; however, multiplanar movements may be more effective, by facilitating the development of motor strategy and intermuscular coordination. Due to their moving axis cam technology, the MuJo™ External Shoulder Machine and Internal Shoulder Machine enable such movement. Furthermore, the range of motion (ROM) through which the shoulder travels can be adjusted to target specific muscles, which may have useful implications within a rehabilitation environment. However, little is currently known about the consequences of varying the ROM whilst using the devices. Therefore, the purpose of this study was to determine the effect of altering ROM on shoulder muscle activity during exercises performed on the MuJo™ Shoulder Machines. Following institutional ethics approval, nine recreationally-active male participants (means ± SDs: age: 25 ± 5 years; body mass: 77.06 ± 11.06 kg; height: 1.76 ± 0.09 m) performed abduction and external rotation, and adduction and internal rotation of the shoulder at twelve different ranges of motion, in a randomised, counterbalanced order. Surface electromyography (EMG) was collected from the upper trapezius, anterior and posterior deltoids, infraspinatus, pectoralis major, and latissimus dorsi. Muscle activity was normalised to the peak activity from a one repetition maximum test, also performed on the machines. The effect of abduction/adduction and rotation angle on normalised peak EMG was analysed via a two-way analysis of variance with repeated measures for each muscle; effect sizes were calculated using partial eta squared (η2p). For the External Machine, a significant main effect for abduction in the upper trapezius was found (F(1.1, 8.7)=15.34, P=0.003, η2p=0.66). Electromyography amplitude was significantly higher at 90° of abduction than at 60° and 30°, and significantly higher at 60° than at 30°. For the anterior deltoid, EMG amplitude was significantly higher at 90° than at 60° of abduction (F(2,16)=7.17, P=0.006, η2p=0.47). A significant main effect for rotation in the latissimus dorsi was found (F(3,24)=7.96, P=0.001, η2p=0.50), with EMG amplitude significantly lower at 0° than at both 90° and 60°. For the Internal Machine, a main effect for rotation in the pectoralis major was observed (F(3, 24)=6.98, P=0.002, η2p=0.47), with EMG amplitude significantly lower at 60° than 30° of rotation. No significant interactions or main effects were observed in the remaining muscles on either machine. In conclusion, altering the ROM results in some changes in muscle activity during abduction and rotation, perhaps indicating a greater requirement for stabilisation during the less constrained repetitions. Further studies incorporating kinematics and inverse dynamics may provide deeper understanding into the effects on motor strategy that may occur when exercising with this device

A Comparison of Biomechanical Variables, Neuromuscular Control and Strength during Controlled and Unexpected Falls on the Outstretched Hands in Young and Older Women

Purpose: This thesis evaluated the age differences in biomechanics and muscle activity during controlled and unexpected descents simulating a fall on the outstretched hands (FOOSH) in women. Laboratory simulation using two different protocols investigated this common mechanism of injury in older and younger women. The primary purpose of the controlled descent (FOOSH 1) was to examine the differences between young and older women to control the post-impact phase of a forward fall descent at three body angles. The primary purpose of the unexpected descent (FOOSH 2) was to examine biomechanical and muscle activity age differences in pre-impact, impact and post-impact phases of a simulated FOOSH. Methods: FOOSH 1 was a cross sectional study comparing twenty healthy young (mean 24.8±3.4 yrs.) and 18 healthy older (68.4±5.7 yrs.) women performing controlled descents on outstretched arms at three body lean angles (60, 45, and 30° from horizontal) and a muscle strength test of the non-dominant UE [isometric (ISO) concentric (CON) and eccentric (ECC)] using an isokinetic dynamometer. FOOSH 2, also a cross sectional design, evaluated twenty young (mean age 22.9 yrs., SD±3.7) and 16 older (mean age 68.1yrs., SD ±5.0) women performing five trials of unexpected FOOSHs at a body lean angle of 60° from horizontal with the same muscle strength testing protocol. A three-dimensional motion capture system (VICON Nexus, VICON, Centennial, CO) and force plate apparatus (OR6-7, AMTI, Watertown, MA) was used to determine the biomechanical measures of peak energy absorption, maximum vertical force, maximum elbow angle and maximum elbow joint extensor moment. Additional biomechanical measures of FOOSH 2 included: elbow angle and elbow angular velocity at impact, elbow joint stiffness, end elbow angle, and impulse. Surface EMG detected muscle activity of six muscle sites: anterior deltoid (AntDEL), pectoralis major (PM), triceps brachii (long head) (TRI), biceps brachii (BB), external oblique (EO) and internal oblique/transversus abdominus (IO/TrA). Results: In FOOSH 1 and FOOSH 2, older women demonstrated decreased CON elbow extensor strength compared with younger women. During FOOSH 1, at all angles, the older women had increased BB activity and decreased EO activity. In FOOSH 2 older women had significantly less IO/TrA activity prior to impact than younger women. The women differed in landing strategy in that younger women had significantly greater elbow joint angle and velocity at impact. Older women demonstrated diminished capacity to absorb energy in both the controlled (30°) and unexpected descent. Significance of findings: This is the first study to investigate biomechanical and muscle activation age differences for a simulated controlled and unexpected forward descent in women. Older women demonstrate differences that could potentially increase their risk of injury during a forward fall. The results of these studies could help clinicians develop fall injury prevention protocols by considering the neuromuscular and biomechanical factors that are important to control a forward descent. The findings suggest that UE and trunk muscle strengthening may be important components to include in a fall injury prevention training program. The modulation of energy absorption capabilities by altering elbow velocity and increasing elbow flexion angles at impact may also be an injury prevention tactic to be adopted

Challenging “Size Matters” Messages: An Exploration of the Experiences of Critical Obesity Scholars in Higher Education

Given that postsecondary institutions are increasingly seen as sites to promote health, critical scholars are calling attention to how the contemporary Western weight-centred health paradigm reinforces a “size matters” message that is fueling harmful attitudes towards and judgments of bodies. As such, research that highlights strategies to promote safe teaching and learning environments for students and faculty, regardless of body shape and size, is of utmost importance. Through 26 participant interviews, this study examines the experiences of critical obesity scholars who teach courses that engage critical approaches to obesity, fatness, and body size. The findings of this study shed light on the developing field of critical obesity scholarship, the types of challenges faced by critical obesity scholars in higher education, and how these scholars are building community as a way of coping with challenges facing the emerging field.   Puisque les institutions d’enseignement post-secondaire sont de plus en plus perçues comme des lieux de promotion de la santé, les acteurs universitaires attirent l’attention sur la façon dont l’approche contemporaine de l’Occident, axée sur le poids corporel, renforce les attitudes discriminatoires et les discours nocifs sur le surplus de poids. En découle l’importance d’effectuer des recherches favorisant des stratégies d’enseignement et d’apprentissage qui soient déconnectées de l’image corporelle. Ainsi, la présente étude analyse les entrevues de 26 professeurs universitaires qui enseignent une approche critique des facteurs traditionnels liés à l’obésité et à la composition corporelle. Les résultats font la lumière sur l’émergence de la mission professorale quant à l’obésité grave, sur les défis que relèvent les chercheurs du domaine en enseignement supérieur, et sur la façon dont ces chercheurs se constituent une nouvelle communauté scientifique afin de surmonter les difficultés rencontrées par les acteurs de cette recherche en émergence