Kotaro Sasaki

How Can We Help Faculty Balance Between Teaching and Scholarly Activities?

Cheryl Schrader et al. — Wed, 14 Dec 2011 12:04:12 PST

Boise State University (BSU), which is among the fastest growing institutions of higher education in the Northwestern United States, is categorized as a Master's College and University (larger programs) by the Carnegie Classifications system. With the vision of becoming a metropolitan research university of distinction, BSU is transforming from a teaching-based to a research-based university. Embracing this transformation, BSU's College of Engineering seeks to establish balanced workloads between teaching and scholarly activities among its faculty by providing appropriate evaluation, rewards, and support. During the 2009-2010 academic year, the college's Teaching and Learning Committee conducted a survey with the full-time faculty members to better understand their perceptions about the current workload ratio between teaching and scholarly activities, the current evaluation and reward systems, and institutional support. A total of 69 full-time faculty members were invited to participate in the survey, and 42 of them (61%) completed the survey. The primary results were: (1) Assistant and associate professors think that their actual teaching load is heavier than their ideal teaching load. (2) Full professors feel that they maintain a good balance between their teaching and scholarly activities and incorporate their research into teaching. (3) The faculty perceive different levels of performance expectations from the university, college and departments. (4) The faculty perceive that the reward system for excellent teaching is vague and insufficient in contrast to the reward system for scholarly activities. These results can be used to develop appropriate guidelines to assist faculty members during the process of institutional transformation from a teaching-based to a research-based university.

Muscle Contributions to the Tibiofemoral Joint Contact Force During Running

Kotaro Sasaki — Mon, 18 Jul 2011 09:48:33 PDT

Running is typically performed at faster speeds than walking, and requires more muscular efforts. Because muscle forces substantially influence joint forces, the tibiofemoral (TF) joint force developed during the stance phase of running is expected to be greater than the force during walking. However, little is known about how individual muscles affect the TF joint force. Such information could be valuable for developing preventive or rehabilitation guidelines for knee joint injuries/diseases including cartilage damage and osteoarthritis that may be associated with high joint loading. Therefore, this study was aimed at identifying individual muscle contributions to the TF joint force during running. Muscle contributions to the axial TF joint force (the force component parallel to the longitudinal axis of the tibia) were computed using a muscle-actuated forward dynamic simulation of running at 2.4 m/s. Using a ground reaction force decomposition technique [1], individual muscle contributions to ground reaction forces were first obtained. Then, only the muscle force of interest and corresponding ground reaction forces were applied to the dynamic system, and resultant axial TF joint force was computed. The simulation showed that the primary contributor to the joint force from early to mid-stance was the quadriceps. From mid- to late stance, the gastrocnemius and the hamstrings contributed to the joint force. To a lesser extent, muscles that do not cross the knee joint (the gluteus maximus and the soleus) also contributed to the TF joint force through their contributions to ground reaction forces.

Individual Muscle Contributions to the Axial Knee Joint Contact Force during Normal Walking

Kotaro Sasaki et al. — Tue, 21 Sep 2010 14:49:33 PDT

Muscles are significant contributors to the high joint forces developed in the knee during human walking. Not only do muscles contribute to the knee joint forces by acting to compress the joint, but they also develop joint forces indirectly through their contributions to the ground reaction forces via dynamic coupling. Thus, muscles can have significant contributions to forces at joints they do not span. However, few studies have investigated how the major lower-limb muscles contribute to the knee joint contact forces during walking. The goal of this study was to use a muscle-actuated forward dynamics simulation of walking to identify how individual muscles contribute to the axial tibio-femoral joint force. The simulation results showed that the vastii muscles are the primary contributors to the axial joint force in early stance while the gastrocnemius is the primary contributor in late stance. The tibio-femoral joint force generated by these muscles was at times greater than the muscle forces themselves. Muscles that do not cross the knee joint (e.g., the gluteus maximus and soleus) also have significant contributions to the tibio-femoral joint force through their contributions to the ground reaction forces. Further, small changes in walking kinematics (e.g., knee flexion angle) can have a significant effect on the magnitude of the knee joint forces. Thus, altering walking mechanics and muscle coordination patterns to utilize muscle groups that perform the same biomechanical function, yet contribute less to the knee joint forces may be an effective way to reduce knee joint loading during walking.

The Relationships between Muscle, External, Internal and Joint Mechanical Work During Normal Walking

Kotaro Sasaki et al. — Tue, 21 Sep 2010 07:48:58 PDT

Muscle mechanical work is an important biomechanical quantity in human movement analyses and has been estimated using different quantities including external, internal and joint work. The goal of this study was to investigate the relationships between these traditionally used estimates of mechanical work in human walking and to assess whether they can be used as accurate estimates of musculotendon and/or muscle fiber work. A muscle-actuated forward dynamics walking simulation was generated to quantify each of the mechanical work measures. Total joint work (i.e. the time integral of absolute joint power over a full gait cycle) was found to underestimate total musculotendon work due to agonist–antagonist co-contractions, despite the effect of biarticular muscle work and passive joint work, which acted to decrease the underestimation. We did find that when the net passive joint work over the gait cycle is negligible, net joint work (i.e. the time integral of net joint power) was comparable to the net musculotendon work (and net muscle fiber work because net tendon work is zero over a complete gait cycle). Thus, during walking conditions when passive joint work is negligible, net joint work may be used as an estimate of net muscle work. Neither total external nor total internal work (nor their sum) provided a reasonable estimate of total musculotendon work. We conclude that joint work is limited in its ability to estimate musculotendon work, and that external and internal work should not be used as an estimation of musculotendon work.

An Algorithm to Estimate Electrical Current Activities in the Human Brain from the Magnetic Field Measured by Superconducting Quantum Interference Devices (in Japanese); Patent number: No 11911103 - Japan

Kotaro Sasaki — Fri, 17 Sep 2010 11:44:31 PDT

Analysis of Potential Muscular Determinants of the Preferred Walk-Run Transition Speed in Human Gait

Kotaro Sasaki — Fri, 17 Sep 2010 11:30:46 PDT

The spontaneous transition from walking to running as walking speed increases is an intriguing neuromotor phenomenon that consistently occurs near 2 m/s in humans. Despite investigations of various metabolic and biomechanical factors, the determinants of the transition have remained elusive. However, no study has investigated the potential influence of intrinsic muscle properties and fiber-tendon interactions as potential determinants. The overall objective of this research was to use a forward dynamical simulation framework in three studies to identify the potential influence of these muscular determinants on the preferred walk-run transition speed (PTS).

In the first study, individual muscle force production was examined as walking speed increased to assess the influence of intrinsic muscle properties on the PTS. The simulation data showed that of all the major lower-extremity muscle groups examined, the ankle plantar flexors were the only muscles to show a decrease in force production, despite an increase in activation, as walking speed approached the PTS. The force reduction was attributed to adverse contractile conditions. Considering the importance of the plantar flexors to providing body support and forward progression, the impaired force generation was deemed an important determinant of the PTS.

In the second study, individual muscle contributions to body support and forward progression in walking and running at the PTS were quantified to clarify differences in muscle function between the two gait modes. The most distinctive difference was the reduced soleus contribution to forward progression in running. All other muscle groups performed similarly between the two gait modes.

In the third study, individual muscle fiber and tendon mechanical work was quantified to examine whether there existed an energetic advantage during walking and running above and below the PTS. The total muscle fiber work was found to be higher in running than walking below the PTS, and higher in walking than running above the PTS. In addition, tendon elasticity utilization was lower in running below the PTS than in running above the PTS. These results highlight the advantages of each gait mode and suggest why walking below the PTS and running above the PTS are the preferred gaits.