The main aim of this study was to investigate the effect of finger spread on the propulsive force production in swimming using computational fluid dynamics. Computer tomography scans of an Olympic swimmer hand were conducted. This procedure involved three models of the hand with differing finger spreads: fingers closed together (no spread), fingers with a small (0.32 cm) spread, and fingers with large (0.64 cm) spread. Steady-state computational fluid dynamics analyses were performed using the Fluent code. The measured forces on the hand models were decomposed into drag and lift coefficients. For hand models, angles of attack of 0°, 15°, 30°, 45°, 60°, 75°, and 90°, with a sweep back angle of 0°, were used for the calculations. The results showed that the model with a small spread between fingers presented higher values of drag coefficient than did the models with fingers closed and fingers with a large spread. One can note that the drag coefficient presented the highest values for an attack angle of 90° in the three hand models. The lift coefficient resembled a sinusoidal curve across the attack angle. The values for the lift coefficient presented few differences among the three models, for a given attack angle. These results suggested that fingers slightly spread could allow the hand to create more propulsive force during swimming.
Daniel A. Marinho, Tiago M. Barbosa, Victor M. Reis, Per L. Kjendlie, Francisco B. Alves, João P. Vilas-Boas, Leandro Machado, António J. Silva, and Abel I. Rouboa
Richard E. Debski, Shon P. Darcy, and Savio L-Y. Woo
Quantitative data on the mechanics of diarthrodial joints and the function of ligaments are needed to better understand injury mechanisms, improve surgical procedures, and develop improved rehabilitation protocols. Therefore, experimental and computational approaches have been developed to determine joint kinematics and the in-situ forces in ligaments and their replacement grafts using human cadaveric knee and shoulder joints. A robotic/universal force-moment sensor testing system is used in our research center for the evaluation of a wide variety of external loading conditions to study the function of ligaments and their replacements; it has the potential to reproduce in-vivo joint motions in a cadaver knee. Two types of computational models have also been developed: a rigid body spring model and a displacement controlled spring model. These computational models are designed to complement and enhance experimental studies so that more complex loading conditions can be examined and the stresses and strains in the soft tissues can be calculated. In the future, this combined approach will improve our understanding of these joints and soft tissues during in-vivo activities and serve as a tool to aid surgical planning and development of rehabilitation protocols.
Sarah A. Roelker, Elena J. Caruthers, Rachel K. Hall, Nicholas C. Pelz, Ajit M.W. Chaudhari, and Robert A. Siston
Musculoskeletal modeling and simulation techniques enable estimates of variables that influence movement, including muscle activations and forces. Many of these variables are not commonly determined in human experiments because of the significant pain and discomfort to the subject with approaches
Matej Supej and Hans-Christer Holmberg
This study examined whether gate setup and turn radii influence energy dissipation in slalom skiing. 3D kinematical measurements were performed over two runs on the same slope in a WC slalom competition with two different gate setups: 1) open gates (OG) and 2) open gates with a delayed gate (DG). Using the arithmetic mean of the skis’ turn radii (R AMS) the slalom turns were divided into 1) initiation phase (R AMS > 15m) and steering phase (R AMS < 15m). The results show differences between OG and DG regarding: 1) the absolute center of gravity’s (CG) velocity, 2) absolute acceleration, 3) CG turn radii and R AMS, 4) ground reaction forces (F) and 5) energy dissipation during skiing (all p < .05). In both gate setups the highest F and the highest energy dissipation were present in the steering phase, whereas the correlation between R AMS and energy dissipation was low (OG: r = .364 and DG: r = .214, both p < .001). In summary, compared with plain open gates, an additional delayed gate prolonged the turn radii and decreased energy dissipation in the beginning of the initiation phase, despite the fact that the relative frequency of occurrence of the highest energy dissipation was higher in DG.
Angelica E. Lang, Soo Y. Kim, Stephan Milosavljevic, and Clark R. Dickerson
mechanisms causing kinematic alterations and to identify contributing muscles that may benefit from focused rehabilitation. 9 , 10 Musculoskeletal modeling allows for estimation of muscle forces and loading strategies for more muscles than can be feasibly measured. For a pathological population, the goal of
Atsushi Makimoto, Yoko Sano, Satoru Hashizume, Akihiko Murai, Yoshiyuki Kobayashi, Hiroshi Takemura, and Hiroaki Hobara
unilateral or bilateral transtibial (below-knee) amputees or transfemoral (above-knee) amputees. Several studies demonstrated that individuals with unilateral transtibial amputation have asymmetric modulation of joint kinetics, 1 ground reaction forces (GRFs), 2 , 3 and related stride kinematics
Megan J. Schroeder, Samuel A. Acuña, Chandramouli Krishnan, and Yasin Y. Dhaher
the risk for degenerative changes such as osteoarthritis. 12 – 16 Contributing to the alterations in knee joint loading are the forces generated by muscles acting directly on the knee joint. Postsurgical rehabilitation strategies, which employ a variety of dynamic tasks aimed at restoring the knee
Sarah A. Roelker, Paul DeVita, John D. Willson, and Richard R. Neptune
across a variety of sports. 3 – 5 In addition, skipping was recently suggested to be a viable supplemental cross-training activity to running. 6 The lower vertical ground reaction forces (GRFs), 2 , 6 lower knee joint contact forces 7 , and higher metabolic cost 7 , 8 experienced during skipping may
Nickolai J.P. Martonick, Ashley J. Reeves, James A. Whitlock, Taylor C. Stevenson, Scott W. Cheatham, Craig P. McGowan, and Russell T. Baker
never followed the recommendations of their IASTM training. 3 , 10 Additionally, clinicians have reported consideration for the quantity of force applied with some attempting to use lighter forces (ie, 500 g [5 N] or less), or more substantial force (ie, 500 g or more), while others have suggested
Amador García-Ramos, Alejandro Torrejón, Antonio J. Morales-Artacho, Alejandro Pérez-Castilla, and Slobodan Jaric
maximum power capacity of an individual, a wide range of resistive forces should be employed to identify the optimum resistive force. 3 , 4 This procedure not only makes the test both long lasting and prone to fatigue, but it also opens the problem of differences in reliability of the obtained outcomes