THE EVOLUTION ACROSS AGES OF EFFICIENCY AND ECONOMY OF (ASSISTED) HUMAN LOCOMOTION AND EXERCISE

Human evolution and ingenuity both collaborated in providing biological/technological tools to move faster, despite of the same actuator, and to better adapt our locomotion to very different environments. While evolution resulted in a versatile musculo-skeletal system featuring optimization and energy-saving mechanisms to produce force and work more effectively, humans also invented passive tools, particularly in the last 4-5 millennia, allowing to moving faster and more economically on land, on/under water and in the air. Among the most featured examples: bone skating on ice, ancient cross-country skiing, bicycling, rowing. But also hand-held masses (Minetti & Ardigo, 2002) enhanced standing long jump and bows/crossbows made us throwing objects at longer distances (a hand-thrown arrow barely reach 25 m, while with a modern bow the distance exceeds 1.3 km). In the past few years we reviewed the historic evolution of passive tools devoted to enhance human locomotion (Minetti, 2004; Ardigo et al., 2005). Sometimes we built replicas of ancient tools (as in cycling - Minetti et al., 2001, cross-country skiing - Formenti et al., 2005 and ice skating - Formenti & Minetti, 2006), in other cases we used modern tools (as fins - Zamparo et al., 2002) in order to study, through biomechanical and metabolic experiments, the progressive adaptation of (the same) muscle to the different machines and environments. The focus of my presentation will be on how limitations of the musculo-skeletal system have been attenuated both inside (gear ratio, tendons) and outside (crank, gears, poles, skis, fins) the body. The relevance into the necessary mechanical work, the economy of transport and the related efficiency of motion/locomotion will be discussed

Technical skills and movement coordination in elite, national and regional level race walkers

Introduction: Race walking (RW) is a very peculiar form of locomotion that requires athletes to walk as fast as possible following two main rules: keep the knee of the supporting leg locked “from the moment of first contact with the ground until the vertical upright position”; and, generate a progression of steps with no visible flight phase. Previous studies have attempted to characterize RW performance, but the use of conventional analytical tools, including kinematic, kinetic and physiological measures, has not been very successful in discriminating between different skill levels and identifying the factors for excellent performance. Improved experimental protocols and finer analytical tools are needed to unveil the subtle differences existing between athletes of different competitive standard.Aim: To compare coordination and coordination variability in RW, and highlight differences between elite-, national- and regional-standard athletes.Method: A cross-sectional design was used to study the changes in coordination variability as a factor of skill level. Fifteen competitive male race walkers were assigned to the Elite, National or Regional groups depending on their season best performance, and were asked to race walk on a treadmill at 15 km/h. Optoelectronic motion capture was used to record 40 gait cycles for each participant. Pelvis and lower limb kinematics was used to study coordination variability through a dynamical system approach [1]. Continuous relative phase and its variability across multiple strides were estimated (Figure 1a). Multiple joint couplings (e.g. hip-knee, knee-ankle) and movement phases (e.g. early and late stance, swing) were considered. Kruskal-Wallis tests were used to assess the between-group differences for each variable.Results and Discussion: Results appeared to support the hypothesis that coordination variability increases during transition phases (e.g. heel-strike and toe-off) (Figure 1b). Overall, less skilled athletes tended to produce larger coordination variability, with significantly higher values of deviation phase during the early-stance phase of the hip-knee (P=0.20), and pelvis-hip (P=0.09) couplings. Individual coordinative patterns showed the potential for characterizing individual peculiarities in specific phases of the movement and to improve the understanding of technical skills, however more work is needed to relate coordinative measures with features of the neuro-muscular-skeletal system organization.References[1] Preatoni, E., Hamill, J., Harrison, A.J., Hayes, K., Van Emmerik, R.E.A., Wilson, C., Rodano, R., 2013. Movement variability and skills monitoring in sports. Sports Biomechanics 12, 69-92.<br/

Recumbent vs. upright bicycles:3D trajectory of body centre of mass, limb mechanical work, and operative range of propulsive muscles

Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations. Data collected at 50, 70, 90 110\ua0rpm during stationary cycling were used to drive musculoskeletal modelling simulation and estimate muscle-tendon length. Results demonstrated that BCoM trajectory, confined in a 15-mm side cube, changed its orientation, maintaining a similar pattern across all cadences in both bicycles. RB displayed a reduced additional mechanical external power (16.1\ua0\ub1\ua09.7\ua0W on RB vs. 20.3\ua0\ub1\ua08.8\ua0W on NB), a greater symmetry on the progression axis, and no differences in the internal mechanical power compared to NB. Simulated muscle activity revealed small significant differences for only selected muscles. On the RB, quadriceps and gluteus demonstrated greater shortening, while biceps femoris, iliacus, and psoas exhibited greater stretch; however, aerodynamics still remains the principal benefit

Shoulder 3D range of motion and humerus rotation in two volleyball spike techniques:injury prevention and performance

Repetitive stresses and movements on the shoulder in the volleyball spike expose this joint to overuse injuries, bringing athletes to a career threatening injury. Assuming that specific spike techniques play an important role in injury risk, we compared the kinematic of the traditional (TT) and the alternative (AT) techniques in 21 elite athletes, evaluating their safety with respect to performance. Glenohumeral joint was set as the centre of an imaginary sphere, intersected by the distal end of the humerus at different angles. Shoulder range of motion and angular velocities were calculated and compared to the joint limits. Ball speed and jump height were also assessed. Results indicated the trajectory of the humerus to be different for the TT, with maximal flexion of the shoulder reduced by 10 degrees, and horizontal abduction 15 degrees higher. No difference was found for external rotation angles, while axial rotation velocities were significantly higher in AT, with a 5% higher ball speed. Results suggest AT as a potential preventive solution to shoulder chronic pathologies, reducing shoulder flexion during spiking. The proposed method allows visualisation of risks associated with different overhead manoeuvres, by depicting humerus angles and velocities with respect to joint limits in the same 3D space

Tuning a hybrid SA based algorithm applied to Optimal Sensor Network Design

El problema de diseño de una red de sensores en plantas de proceso (Sensor Network Design Problem, SNDP) consiste en determinar las variables de proceso que deben ser medidas, a fin de alcanzar el grado de conocimiento requerido de dicha planta. Proponemos resolver el problema SNDP en plantas de tamaño y complejidad creciente utilizando un algoritmo híbrido basado en Recocido Simulado (Hybrid Simulated Annealing, HSA) como metaheurística principal y Búsqueda Tabú con Oscilación Estratégica como metaheurística subordinada. Investigamos los ajustes de los parámetros de control para obtener el mejor desempeño del HSA. Los resultados experimentales indican que el HSA puede efectivamente encontrar una solución de buena calidad en tiempos de computo razonable. Mas a ´ un, HSA muestra buenas ´ características en la solución de SNDP en comparación con algoritmos propuestos en la literatura.Sensor network design problem (SNDP) in process plants includes the determination of which process variables should be measured to achieve a required degree of knowledge about the plant. We propose to solve the SNDP problem in plants of increasing size and complexity using a hybrid algorithm based on Simulated Annealing (HSA) as main metaheuristic and Tabu Search embedded with Strategic Oscillation (SOTS) as a subordinate metaheuristic. We studied the tuning of control parameters in order to improve the HSA performance. Experimental results indicate that a high-quality solution in reasonable computational times can be found by HSA effectively. Moreover, HSA shows good features solving SNDP compared with proposals from the literature.Fil: Hernandez, Jose Luis. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Salto, Carolina. Universidad Nacional de la Pampa. Facultad de Ingeniería. Departamento de Informatica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Minetti, Gabriela Fabiana. Universidad Nacional de la Pampa. Facultad de Ingeniería. Departamento de Informatica; ArgentinaFil: Carnero, Mercedes del Carmen. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; ArgentinaFil: Bermudez, Carlos Alberto. Universidad Nacional de la Pampa. Facultad de Ingeniería. Departamento de Informatica; ArgentinaFil: Sanchez, Mabel Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Race Walking Ground Reaction Forces at Increasing Speeds: A Comparison with Walking and Running

Race walking has been theoretically described as a walking gait in which no flight time is allowed and high travelling speed, comparable to running (3.6\u20134.2 m s1), is achieved. The aim of this study was to mechanically understand such a \u201chybrid gait\u201d by analysing the ground reaction forces (GRFs) generated in a wide range of race walking speeds, while comparing them to running and walking. Fifteen athletes race-walked on an instrumented walkway (4 m) and three-dimensional GRFs were recorded at 1000 Hz. Subjects were asked to performed three self-selected speeds corresponding to a low, medium and high speed. Peak forces increased with speeds and medio-lateral and braking peaks were higher than in walking and running, whereas the vertical peaks were higher than walking but lower than running. Vertical GRF traces showed two characteristic patterns: one resembling the \u201cM-shape\u201d of walking and the second characterised by a first peak and a subsequent plateau. These dierent patterns were not related to the athletes\u2019 performance level. The analysis of the body centre of mass trajectory, which reaches its vertical minimum at mid-stance, showed that race walking should be considered a bouncing gait regardless of the presence or absence of a flight phase

The 3d body centre of mass trajectory before and after total knee arthroplasty:symmetry and mechanical work

The kinematics of walking on treadmill were collected and the 3D trajectory of the body centre of mass was computed in subjects suffering from mono-lateral knee osteoarthritis, before and after total knee arthroplasty. Experimental data showed after 6 months from surgery significant improvements in many biomechanical parameters as gait symmetry indices and total work done