Foot orthoses affect frequency components of muscle activity in the lower extremity.

The purpose of this study was to quantify the effects of selected foot orthoses on muscle activity in the lower extremity during running. Nine male and 12 female recreational runners, clinically and functionally classified as 'pronators', volunteered for this study and performed over-ground running trials at 4m/s in each of four experimental conditions: control, posting, molding, and posting & molding. Electromyographic (EMG) signals were recorded from seven lower extremity muscles. Wavelet analysis was performed to obtain EMG intensities in two frequency bands that were averaged for the pre-heel-strike and post-heel-strike intervals and for 30-100% of stance phase. Posting and custom-molding of foot orthoses increased the global EMG intensity of most muscles of the lower extremity for the stance phase of running (P < 0.05). The increases in EMG intensity were greater in the high- than in the low-frequency bands for some lower extremity muscles (P < 0.05). The effects on muscle activity of posting and custom-molding of foot orthoses differed between the three phases of running gait. The three tested foot orthoses did affect lower extremity muscle activity differently and these effects were specific to the phases of running gait. Combinations of increased requirements of controlling joint motion and minimizing soft tissue vibrations may have led to greater increases in shank muscle activity for the posted condition. The substantial changes in EMG due to orthotic interventions found in this study documents the importance of the study of muscle activity as a reaction to shoe inserts and foot orthoses.

[1]  Benno M. Nigg,et al.  Consistent Immediate Effects of Foot Orthoses on Comfort and Lower Extremity Kinematics, Kinetics, and Muscle Activity , 2004 .

[2]  Walter Herzog,et al.  Determining patterns of motor recruitment during locomotion. , 2002, The Journal of experimental biology.

[3]  James M Wakeling,et al.  Wave properties of action potentials from fast and slow motor units of rats , 2002, Muscle & nerve.

[4]  Benno M. Nigg,et al.  Impact forces in running , 1997 .

[5]  P. Ludewig,et al.  Electromyographic effects of foot orthotics on selected lower extremity muscles during running. , 1999, Archives of physical medicine and rehabilitation.

[6]  M. Schieppati,et al.  Medium-latency response to muscle stretch in human lower limb: estimation of conduction velocity of group II fibres and central delay , 1998, Neuroscience Letters.

[7]  Benno M Nigg,et al.  Muscle activity damps the soft tissue resonance that occurs in response to pulsed and continuous vibrations. , 2002, Journal of applied physiology.

[8]  Benno M. Nigg,et al.  Surface EMG shows distinct populations of muscle activity when measured during sustained sub-maximal exercise , 2001, European Journal of Applied Physiology.

[9]  T. Masuda,et al.  Fibre conduction velocity and fibre composition in human vastus lateralis , 2004, European Journal of Applied Physiology and Occupational Physiology.

[10]  A. Gefen,et al.  Biomechanical analysis of fatigue-related foot injury mechanisms in athletes and recruits during intensive marching , 2002, Medical and Biological Engineering and Computing.

[11]  B M Nigg,et al.  Shoe inserts and orthotics for sport and physical activities. , 1999, Medicine and science in sports and exercise.

[12]  Benno M Nigg,et al.  Orthotic comfort is related to kinematics, kinetics, and EMG in recreational runners. , 2003, Medicine and science in sports and exercise.

[13]  C. Saltzman,et al.  The effect of foot orthotics on three-dimensional kinematics of the leg and rearfoot during running. , 1995, The Journal of orthopaedic and sports physical therapy.

[14]  A. Mündermann,et al.  Foot orthotics affect lower extremity kinematics and kinetics during running. , 2003, Clinical biomechanics.

[15]  R. Kram,et al.  Energy cost and muscular activity required for propulsion during walking. , 2003, Journal of applied physiology.

[16]  E. P. Mccutcheon,et al.  Body acceleration distribution and O2 uptake in humans during running and jumping. , 1980, Journal of applied physiology: respiratory, environmental and exercise physiology.

[17]  A. J. van den Bogert,et al.  Effects of foot orthoses on skeletal motion during running. , 2000, Clinical biomechanics.

[18]  J. Duysens,et al.  Widespread short-latency stretch reflexes and their modulation during stumbling over obstacles , 1999, Brain Research.

[19]  Ronald L. Valmassy Dpm Ms.  Clinical Biomechanics of the Lower Extremities , 1996 .

[20]  B Gerdle,et al.  Do the fibre-type proportion and the angular velocity influence the mean power frequency of the electromyogram? , 1988, Acta physiologica Scandinavica.

[21]  J. O'Connor,et al.  Kinematics of the human ankle complex in passive flexion; a single degree of freedom system. , 1999, Journal of biomechanics.

[22]  Silvia A. Pascual,et al.  Altering muscle activity in the lower extremities by running with different shoes. , 2002, Medicine and science in sports and exercise.

[23]  B. Nigg,et al.  Muscle activity reduces soft-tissue resonance at heel-strike during walking. , 2003, Journal of biomechanics.

[24]  J. O'Connor,et al.  The components of passive knee movement are coupled to flexion angle. , 2000, Journal of biomechanics.

[25]  Development of the functional orthosis. , 1994, Clinics in podiatric medicine and surgery.

[26]  Vinzenz von Tscharner,et al.  Intensity analysis in time-frequency space of surface myoelectric signals by wavelets of specified resolution , 2000 .

[27]  Root Ml.  Development of the functional orthosis. , 1994 .