The Effect of Hamstring Contractions in the Activation of the Abdominal Muscles during a Standard Abdominal Crunch

Purpose: The purpose of this study was to determine the effect of a hamstring contraction on the abdominal musculature during a standard crunch. Studies in the past have looked at abdominal and core strengthening, exercise equipment, and exercise techniques and their effect on abdominal electromyography (EMG). Few published studies have looked at the effect on the abdominals during a modified crunch, which is a hamstring contraction during a standard crunch. Methods: Participants (n=30) for this study were between the ages of 18 and 60 with no history of acute or chronic back pain or major abdominal surgery. EMG was used to record the activity of four muscle groups including the: upper rectus abdominus (URA), lower rectus abdominus (LRA), external obliques (EO), and the biceps femoris during a standard crunch and also during a modified crunch. Data analysis compared EMG output to each participant\u27s individual maximal voluntary contraction (MVC) for each muscle group analyzed. Results: There was a significant (p\u3c0.05) increase in the average mean difference in the LRA of + 26.89% and EO of +46.3% in EMG activity during the modified crunch. URA displayed an increase of +2.25%; however, it was not found to be statistically significant. Discussion: In this study there was an increase in abdominal EMG output for the modified crunch; however, other factors that need to be considered include: the effects of gender, age, previous abdominal training, influence of pathologies, and other musculature involvement

Coastal natural and nature-based features: international guidelines for flood risk management

Natural and nature-based features (NNBF) have been used for more than 100 years as coastal protection infrastructure (e.g., beach nourishment projects). The application of NNBF has grown steadily in recent years with the goal of realizing both coastal engineering and environment and social co-benefits through projects that have the potential to adapt to the changing climate. Technical advancements in support of NNBF are increasingly the subject of peer-reviewed literature, and guidance has been published by numerous organizations to inform technical practice for specific types of nature-based solutions. The International Guidelines on Natural and Nature-Based Features for Flood Risk Management was recently published to provide a comprehensive guide that draws directly on the growing body of knowledge and practitioner experience from around the world to inform the process of conceptualizing, planning, designing, engineering, and operating NNBF. These Guidelines focus on the role of nature-based solutions and natural infrastructure (beaches, dunes, wetlands and plant systems, islands, reefs) as a part of coastal and riverine flood risk management. In addition to describing each of the NNBF types, their use, design, implementation, and maintenance, the guidelines describe general principles for employing NNBF, stakeholder engagement, monitoring, costs and benefits, and adaptive management. An overall systems approach is taken to planning and implementation of NNBF. The guidelines were developed to support decision-makers, project managers, and practitioners in conceptualizing, planning, designing, engineering, implementing, and maintaining sustainable systems for nature-based flood risk management. This paper summarizes key concepts and highlights challenges and areas of future research

Introduction to the Special Series, “Incorporating Nature-based Solutions into the Built Environment”

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Sediment Characteristics and Bioavailability of Sorbed Neutral Organic Compounds

Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant correlation between sediment toxicity and sediment characteristics (organic carbon, cation exchange capacity, particle size distribution, particle surface area). Fluoranthene amended sediments with similar organic carbon contents do not yield similar toxicities due to sorbed fluoranthene and thus do not support the organic carbon normalization approach for evaluating sediment quality or for sediment criteria development

Realizing multiple benefits in u s army corps of engineers usace baltimore district dredging projects through application of engineering with nature principles

Document type: Repor