Sibley School of Mechanical and Aerospace Engineering

Research Interests

My work is dedicated to understanding the neural control of complex neuromuscular systems (e.g., the human hand). Towards this end, I employ a synergy of experimental and computational techniques. For example, by recording intramuscular EMGs from all 7 muscles of the index finger, I am examining the coordination pattern (i.e., relative activations among muscles) used to perform both "simple" (e.g., index finger abduction/flexion) and "complex" (e.g., hybrid motion-force) tasks. These experimental procedures in turn inform theoretical work to characterize neuromuscular function through experimentally-valid neuromuscular computer models. By combining rigorous experimental and computational methods, I am developing novel experimental approaches to characterize the response of the neuromuscular system to acute (e.g., strength training) and chronic (e.g., aging) adaptations.

Education

• Ph.D. Integrative Physiology, University of Colorado, Boulder, CO 2005
  
• M.S. Kinesiology, The University of Michigan, Ann Arbor, MI 1998
• B.S. Kinesiology, The University of Michigan, Ann Arbor, MI 1990

Professional Experience

• 2007-present, Adjunct Assistant Professor Physical Therapy, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA
• 2005-present, Postdoctoral Research Fellow, Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, Advisor: Francisco J. Valero-Cuevas
• 2000-2005, Neurophysiology of Movement Laboratory, University of Colorado, Boulder, CO, Advisor: Roger M. Enoka
• 1998-2000, Information Technology Specialist, International Business Machines (IBM), Boulder, CO
• 1992-1998, Head Strength and Conditioning Coordinator, Providence College Athletic Department, Providence, RI
• 1990-1992, Graduate Assistant Strength and Conditioning Coach, University of Michigan Athletic Department, Ann Arbor, MI

Publications

• Shinohara M, Keenan KG, Enoka RM. Temporal and spectral measures of index finger kinematics during steady contractions. J Neurosci Meth. In press.
• Keenan KG, Valero-Cuevas FJ. Epoch length to accurately estimate the amplitude of interference EMG is likely the result of unavoidable amplitude cancellation. In submission.
• Keenan KG, Valero-Cuevas FJ. Index finger abduction requires a complex muscle coordination pattern. In preparation.
• Keenan KG, Ashley D, Valero-Cuevas FJ. Muscle mechanics do not modulate maximal voluntary fingertip force in hybrid motion-force tasks. In preparation.
• Keenan KG, Valero-Cuevas FJ. Experimentally-valid predictions of muscle force and EMG in models of motor unit function are most sensitive to neural properties. J Neurophysiol 98: 1581-1590, 2007.
• Keenan KG, Farina D, Meyer F, Merletti R, Enoka RM. Sensitivity of the cross-correlation between simulated surface EMGs for two muscles to detect motor unit synchronization. J Appl Physiol 102(3):1193-201, 2007.
• Keenan KG, Farina D, Merletti R, Enoka RM. Amplitude cancellation reduces the size of motor unit potentials averaged from the surface EMG. J Appl Physiol 100: 1928-1937, 2006.
• Keenan KG, Farina D, Merletti R, Enoka RM. Influence of motor unit properties on the size of the simulated evoked surface EMG potential. Exp Brain Res 169: 37-49, 2006.
• Shinohara M, Keenan KG, Enoka RM. Fluctuations in motor output during steady contractions are weakly related across contraction types and between hands. Muscle Nerve 31: 741-750, 2005.
• Keenan KG, Farina D, Maluf KS, Merletti R, Enoka RM. Influence of amplitude cancellation on the simulated surface electromyogram. J Appl Physiol 98: 120-131, 2005.
• Shinohara M, Keenan KG, Enoka RM. Contralateral activity in a homologous hand muscle during voluntary contractions is greater in old adults. J Appl Physiol 94: 966-974, 2003.

Abstracts

• Keenan KG, Ashley D, McNamara III RV, Song S, Kanar FJ, Valero-Cuevas FJ. Muscle mechanics do not suffice to explain the reduction in maximal voluntary fingertip force in combined motion and force tasks. 37th Annual Meeting of the Society for Neuroscience, San Diego, CA, 81.13, 2007.
• Keenan KG, Valero-Cuevas FJ. Improving models of motor unit function is best done by refining their neural mechanisms. 31st Annual Meeting of the American Society of Biomechanics, Stanford, CA, Podium 20: Motor Units, 2006.
• Medina FA, Venkadesan M, Keenan KG, McNamara III RV, Backus SL, Song S, Price C, Valero-Cuevas FJ. The transition between muscle coordination patterns is context dependent. 31st Annual Meeting of the American Society of Biomechanics, Stanford, CA, Podium 1: Motor Control 1, 2006.
• Keenan KG, Valero-Cuevas FJ. Identification of parameter sets for experimentally-valid simulation of motor units. 17th Annual Meeting of the Neural Control of Movement Meeting, Seville, Spain, 2007.
• Keenan KG, McNamara III RV, Backus SI, Schieber MH, Valero-Cuevas FJ. Index finger abduction is a complex motor task. 36th Annual Meeting of the Society for Neuroscience, Atlanta, GA, 655.18, 2006.
• Keenan KG, Valero-Cuevas FJ. EMG amplitude is most sensitive to the range in innervation numbers: a large-scale computational sensitivity analysis. 16th Annual Meeting of the Neural Control of Movement Meeting, Key Biscayne, FL, Limb Motor Function: Synergies, D-05, 2006.
• Keenan KG, Farina D, Enoka RM. Motor unit synchronization and the cross-correlation of simulated surface EMGs for two muscles. 35th Annual Meeting of the Society for Neuroscience, Washington, DC, 399.5, 2005.
• Keenan KG, Farina D, Merletti R, Enoka RM. Detection of motor-unit activity in the spike-triggered average of the simulated electromyogram before and after rectification. 34th Annual Meeting of the Society for Neuroscience, San Diego, CA, 188.11, 2004.
• Aidoor SS, Keenan KG, Farina D, Jesunathadas M, Enoka RM. The accuracy of detecting onset of muscle activity from the surface electromyogram during gait. Annual Meeting of the American College of Sports Medicine (ACSM), Indianapolis, IN, 2434: Board #166, 2004.
• Keenan KG, Farina D, Merletti R, Enoka RM. M-wave size is influenced by the range of conduction velocities and the timing of motor unit action potentials. Proceedings of the 15th International Society of Electromyography and Kinesiology (ISEK) Congress, edited by Roy SH, Bonato P and Meyer J, Boston, MA, p. 174, 2004.
• Shinohara M, Keenan KG, Enoka RM. Measures of steadiness are influenced by the frequency content of the signals. Annual Meeting of the American College of Sports Medicine (ACSM), Indianapolis, IN, 36(5) suppl: S6, 2004.
• Shinohara M, Keenan KG, Enoka RM. Fluctuations in motor output by a hand muscle are not strongly correlated between hands or contraction types in young and old adults. 33rd Annual Meeting of the Society for Neuroscience, New Orleans, 914.14, 2003.
• Keenan KG, Farina D, Maluf KS, Merletti R, Enoka RM. Age-associated changes in motor unit properties reduce signal cancellation in the simulated electromyogram. 33rd Annual Meeting of the Society for Neuroscience, New Orleans, LA, 914.11, 2003.
• Keenan KG, Shinohara M, Enoka RM. Contralateral activity in a homologous hand muscle during ipsilateral contractions can be greater in old adults. 32th Annual Meeting of the Society for Neuroscience, Orlando, FL, 665.12, 2002.

Manuscript Reviewer

• Biomedical Signal Processing and Control
• Ergonomics
• European Respiratory Journal
• IEEE Transactions on Biomedical Research
• Journal of Applied Biomechanics
• Journal of Applied Physiology
• Journal of Neurophysiology
• Mathematical Biosciences
• Medicine & Science in Sports & Exercise