Biomechanics (Chapter 9)

Biomechanics is a discipline. A discipline deals with understanding, predicting, and explaining phenomena within a content domain, and biomechanics is the study of the human body in motion. Kinesiology, the parent discipline of biomechanics, is a science that investigates movement. Biomechanical research in human development focuses on evaluating essential movement patterns across the human life span. Biomechanical analysis is specifically important in quantifying the developmental motor skills and movement patterns such as walking, kicking, jumping, throwing, and catching. Biomechanical research also involves studying the movement patterns of injured and disabled people. Forensic biomechanists are invited to analyze evidence, clarify some of the most important issues, and facilitate the decisions of the jury. Motion recording devices use optical lenses to capture body motion and provide permanent recorded images of movement that can be evaluated with more precision than perception with the naked eye alone

Kinematic differences between professional and lay rescuers with and without the use of real-time cpr feedback

Purpose: Guideline-compliant cardiopulmonary resuscitation (CPR) performance can be achieved with training and use of real-time feedback. Kinematic differences are reported between experts and novices in various motor tasks. The aim of this pilot study was to investigate differences in kinematics between professional and lay rescuers during CPR performed on a manikin with and without feedback. Methods: Professional (n = 5) and lay rescuers (n = 11) performed two minutes of continuous chest compressions on a manikin for two trials. Real-time CPR feedback provided by a defibrillator was disabled in the first trial and enabled in the second. CPR pads containing an accelerometer were used to calculate individual compression characteristics. Participants were instrumented for electromyography (EMG) and inertial motion capture and a motion capture marker was placed on the top hand. Paired and independent-sample t-tests and Pearson correlations were conducted in STATA 15.1. Results: CPR feedback increased compression depth in lay rescuers (p \u3c 0.05) to achieve guideline compliance. Lower bilateral hip range of motion (ROM) was recorded in lay rescuers compared with professionals without feedback (p \u3c 0.05), but hip ROM was increased in lay rescuers with feedback enabled (p \u3c 0.05). Hip ROM was associated with compression depth on both right (r = 0.61, p \u3c 0.01) and left sides (r = 0.65, p \u3c 0.01) for all rescuers. Greater left shoulder flexion was measured in lay rescuers both with (p \u3c 0.05) and without feedback (p \u3c 0.05). Lower extremity muscle coactivation indexes (CI) indicate greater hip extensor activity in professionals with feedback on both left (1.42 ± 0.17 vs. 0.87 ± 0.12, p \u3c 0.05) and right sides (1.33 ± 0.16 vs. 0.99 ± 0.07, p \u3c 0.05)

Abstract 482: Differences in Ground Reaction Forces and Chest Compression Release Velocity in Professional and Lay Rescuers With and Without the Use of Real-Time CPR Feedback

Purpose: Chest compression release velocity (CCRV) has been associated with survival and favorable neurological outcome after cardiac resuscitation. Both complete chest release and high CCRV contribute to improved venous return during CPR. Differences in compression forces delivered by professional and lay rescuers are reported, which may contribute to differences in CCRV. The aim of this pilot study was to investigate differences in ground reaction force (GRF) and CCRV between professional and lay rescuers during CPR performed on a manikin with and without real-time feedback. Methods: Professional (n = 5) and lay rescuers (n = 11) performed two minutes of continuous compressions on a manikin positioned over a force plate for two trials. CPR feedback provided by a defibrillator was disabled in the first trial and enabled in the second. CPR pads containing an accelerometer were used to calculate individual compression characteristics. Relative maximum and minimum GRFs were calculated for each compression cycle and averaged over each trial. Paired and independent sample t tests and Pearson correlations were conducted in STATA 15.1. Results: CCRV was higher in professionals vs. lay rescuers with feedback disabled and enabled (p\u3c0.05). Professionals had greater maximal and lower minimum forces than lay rescuers without feedback (p\u3c0.05), though there were no differences between groups with feedback enabled (Table 1). CCRV was associated with minimum force (r = -0.63, p\u3c0.01) and force range (r = 0.78, p\u3c0.01) in all rescuers. Analysis of GRFs by CCRV for all rescuers indicated lower force minimum (9.71 + 3.16 N, p\u3c0.05) with CCRV \u3e400 mm/s in comparison to CCRV 300-400 mm/s (39.73 + 8.91 N) and CCRV 200-300 mm/s (63.82 + 16.98 N). Conclusions: CPR feedback attenuated differences in GRF between professional and lay rescuers. CCRV was greater in professionals and was associated with measures of GRF, and thus may serve as an indicator of both velocity and amount of chest release

Impact of Adiposity on Postural Control at the Onset of Sitting

Little research has examined the impact of infant adiposity on the quality of gross motor behavior, especially in sitting through measuring postural control. Therefore, the purpose of this study was to examine the impact of adiposity as measured by skinfold thickness (SFT) on postural control at the onset of sitting in typically developing infants. Nineteen infants (n=8 high SFT, n=11 lower SFT) participated in a pilot study examining the relationship between infant physical activity and postural control. High SFT was classified as having a subscapular and triceps measurement in the 85th percentile or above according to the WHO age and sex-specific standards. Infant’s postural control was measured within one week of the onset of sitting. Three trials of sitting were recorded while infants were sitting on an AMTI force platform and postural sway measures were recorded. Sway movement patterns were analyzed using the range for both the anterior/posterior (AP) and medial/lateral (ML) direction as well as sway path. The results revealed that there were no significant differences between infants in Range in the AP and ML directions. However, Sway Path was significantly different as infants with high SFT showed lower Sway Path values in comparison to lower SFT infants. These results suggest that infants with high SFT cover significantly less distance with their center of pressure than infants with lower SFT. This finding suggest that infants with more adiposity adopt a different postural control strategy. This altered strategy, may limit exploration early in development, which may hinder the progression of cognitive emotional and social processes, however more research is needed

Linear and Nonlinear Measures of Postural Control in a Toddler With Cerebral Palsy: Brief Report

Purpose: The purpose of this study was to describe changes in linear and nonlinear measures of postural control along with motor outcomes in a young child with cerebral palsy. Summary of Key Points: Posturography in sitting and standing, the Gross Motor Function Measure-66 (GMFM-66), and the Early Clinical Assessment of Balance (ECAB) were performed prior to, during, and after physical therapy. The child demonstrated independent sitting throughout the study and developed independent standing during the study. He made improvements in the GMFM-66 and ECAB throughout the study. Higher average values were found in all linear and nonlinear measures in standing when compared to sitting, which may indicate less predictable movement due to less experience with standing. Recommendations for Clinical Practice: Greater variability and lower predictability in postural control likely reflect early stages of skill acquisition. Research is needed to understand the optimal levels of movement variability and predictability

Supervised walking exercise therapy improves gait biomechanics in patients with peripheral artery diseas

Objective In patients with peripheral artery disease (PAD), supervised exercise therapy is a first line of treatment because it increases maximum walking distances comparable with surgical revascularization therapy. Little is known regarding gait biomechanics after supervised exercise therapy. This study characterized the effects of supervised exercise therapy on gait biomechanics and walking distances in claudicating patients with PAD. Methods Forty-seven claudicating patients with PAD underwent gait analysis before and immediately after 6 months of supervised exercise therapy. Exercise sessions consisted of a 5-minute warmup of mild walking and stretching of upper and lower leg muscles, 50 minutes of intermittent treadmill walking, and 5 minutes of cooldown (similar to warmup) three times per week. Measurements included self-perceived ambulatory limitations measured by questionnaire, the ankle-brachial index (ABI), walking distance measures, maximal plantar flexor strength measured by isometric dynamometry, and overground gait biomechanics trials performed before and after the onset of claudication pain. Paired t-tests were used to test for differences in quality of life, walking distances, ABI, and maximal strength. A two-factor repeated measures analysis of variance determined differences for intervention and condition for gait biomechanics dependent variables. Results After supervised exercise therapy, quality of life, walking distances, and maximal plantar flexor strength improved, although the ABI did not significantly change. Several gait biomechanics parameters improved after the intervention, including torque and power generation at the ankle and hip. Similar to previous studies, the onset of claudication pain led to a worsening gait or a gait that was less like healthy individuals with a pain-free gait. Conclusions Six months of supervised exercise therapy produced increases in walking distances and quality of life that are consistent with concurrent improvements in muscle strength and gait biomechanics. These improvements occurred even though the ABI did not improve. Future work should examine the benefits of supervised exercise therapy used in combination with other available treatments for PAD

Supervised Walking Exercise Therapy Improves Gait Biomechanics in Patients with Peripheral Artery Disease

Peripheral artery disease (PAD) is commonly caused by atherosclerotic build-up of plaque within the peripheral arteries, affecting the blood flow to the legs. The most common presentation of PAD is intermittent claudication; a condition in which when the patient walks the metabolic demands of the lower limbs exceed the limited supply of blood, causing exercise- induced discomfort and decreased walking ability. Walking exercise is the first line of treatment in patients with claudication with the best results achieved in patients undergoing supervised exercise therapy for at least three months. Supervised walking exercise results in increased maximum walking distances comparable to those seen following surgical revascularization. We tested the hypothesis that supervised exercise training of PAD patients with claudication improves walking distances in association with improved gait biomechanics. Our research involved 47 patients going through a twenty-four week (three sessions per week), supervised walking exercise therapy program. Each session included a 5 minute warm-up, 50 minutes of treadmill exercise, and 5 minutes of cool down. Patients underwent gait analysis before and immediately following exercise therapy. Our hypothesis was partially supported. Both walking distances and several, but not all, gait biomechanics variables significantly improved following supervised walking exercise therapy

Introduction to Exercise Science: 5th Edition

The fifth edition of Introduction to Exercise Science introduces students to every core area of study in the discipline. It comprises concise chapters which introduce the history, key lines of inquiry relating to both health and performance, technology, certifications, professional associations, and career opportunities associated with each area. No other book offers such a wide-ranging, evidence-based introduction to exercise science. Written by leading and experienced experts, chapters include: reading and interpreting literature measurement in exercise science anatomy in exercise science exercise physiology exercise epidemiology athletic training exercise and sport nutrition biomechanics motor control exercise and sport psychology Packed with pedagogical features—from journal abstract examples to study questions and further reading suggestions—and accompanied by a website including practical lab exercises, Introduction to Exercise Science is a complete resource for a hands-on introduction to the core tenets of exercise science. It is an engaging and invaluable textbook for students beginning undergraduate degrees in Kinesiology, Sport & Exercise Science, Sports Coaching, Strength & Conditioning, Athletic Training, Sports Therapy, Sports Medicine, and Health & Fitness.https://digitalcommons.unomaha.edu/biomechanicsbooks/1000/thumbnail.jp