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D Casey Kerrigan

Publications and source records attributed to D Casey Kerrigan.

18 recordsLinked to original sources
PubMed2006

A kinematic and kinetic comparison of overground and treadmill walking in healthy subjects.

INTRODUCTION: Gait evaluation protocols using instrumented treadmills will be increasingly used in the near future. For this reason, it must be shown that using instrumented treadmills will produce measures of the ground reaction force adequate for inverse dynamic analysis, and differences between treadmill and overground gait must be well characterized. METHODS: Overground walking kinetics were estimated with the subjects walking at their self-selected comfortable walking speed. For the treadmill gait trials, the subjects walked on two treadmills, such that heel-strike occurred on the forward treadmill and toe-off occurred on the trailing treadmill. The treadmill was set to the average overground walking speed. Overground and treadmill data were evaluated using Vicon Plug-in Gait. The differences between the maxima and minima of kinematic and kinetic parameters for overground and treadmill gait were evaluated. RESULTS: The kinematics of treadmill and overground gait were very similar. Twelve of 22 kinematic parameter maxima were statistically significantly different (p<0.05), but the magnitude of the difference was generally less than 2 degrees . All GRF maxima were found to be statistically significantly smaller for treadmill versus overground gait (p<0.05) as were 15 of 18 moment, and 3 of 6 power maxima. However, the magnitude of the differences was comparable to the variability in normal gait parameters. The sagittal plane ankle moments were not statistically different for treadmill and overground gait. DISCUSSION: We have shown that treadmill gait is qualitatively and quantitatively similar to overground gait. Differences in kinematic and kinetic parameters can be detected in matched comparisons, particularly in the case of kinetic parameters. However, the magnitudes of these differences are all within the range of repeatability of measured kinematic parameters. Thus, the mechanics of treadmill and overground gait are very similar. CLINICAL SIGNIFICANCE: Having demonstrated the essential equivalence of treadmill and overground gait, it is now possible for clinical movement analysis to take advantage of treadmill-based protocols.

Adolescent↗
PubMed2006

Testing of a tri-instrumented-treadmill unit for kinetic analysis of locomotion tasks in static and dynamic loading conditions.

In this study, we present a multi-treadmill system instrumented with three force platforms capable of measuring vertical and shear ground reaction forces and moments during both walking and running. Linearity, belts speed variations, repeatability of the measures, cross-talk, natural frequency, instrumental noise, moving part induced noise and drift were investigated. The noise due to vibrations and to moving parts was also investigated having a subject walking and running on the treadmill. The linearity test results showed a high linearity of all three treadmill force platforms, and vertical force natural frequency values of 219, 308, 307Hz, obtained for the three force platforms, were considered appropriate for the investigation of walking and running. The instrumental noise did not appear to be a significant source of error. The characteristics of the noise due to vibrations and moving parts changed when in the presence of a subject walking and running on the treadmill. For walking trials, averaging of gait cycles led to a systematic improvement of the signal to noise ratio, particularly for the medio-lateral component of the force. For running trials, even though averaging was not as beneficial as for walking trials, the greater force amplitude led to a better signal to noise ratio value. This instrumented treadmill demonstrated acceptable accuracy and signal to noise ratios for all ground reaction force components such that it can be useful for a variety of research and clinical gait analysis applications.

Acceleration↗
PubMed2005

Moderate-heeled shoes and knee joint torques relevant to the development and progression of knee osteoarthritis.

OBJECTIVE: To determine if women's dress shoes with heels of just 1.5 in (3.8 cm) in height increases knee joint torques, which are thought to be relevant to the development and/or progression of knee osteoarthritis (OA) in both the medial and patellofemoral compartments. DESIGN: Randomized controlled trial. SETTING: A 3-dimensional motion analysis gait laboratory. PARTICIPANTS: Twenty-nine healthy young women (age, 26.7+/-5.0 y) and 20 healthy elderly adult women (age, 75.3+/-6.5 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak external varus knee torque in early and late stance and prolongation of flexor knee torque in early stance. Three-dimensional data on lower-extremity torques and motion were collected during walking while (1) wearing shoes with 1.5-in high heels and (2) wearing control shoes without any additional heel. Data were plotted and qualitatively compared; major peak values and timing were statistically compared between the 2 conditions using paired t tests. RESULTS: Peak knee varus torque during late stance was statistically significantly greater with the heeled shoes than with the controls, with increases of 14% in the young women and 9% in the elderly women. With the heeled shoes, the early stance phase knee flexor torque was significantly prolonged, by 19% in the young women and by 14% in elderly women. Also, the peak flexor torque was 7% higher with the heeled shoe in the elderly women. CONCLUSIONS: Even shoes with moderately high heels (1.5 in) significantly increase knee torques thought to be relevant in the development and/or progression of knee OA. Women, particularly those who already have knee OA, should be advised against wearing these types of shoes.

Adult↗
PubMed2005

Reduced hip extension in the elderly: dynamic or postural?

OBJECTIVE: To test the hypothesis that reduced hip extension and increased anterior pelvic tilt in the elderly are dynamic gait phenomena that do not occur during normal standing posture. DESIGN: Experimental. SETTING: Gait laboratory. PARTICIPANTS: Twenty-five older adult subjects (mean age +/- standard deviation, 71+/-5 y) and 25 young adult subjects (mean age, 26+/-5 y). INTERVENTION: Subjects were observed during standing and walking at self-determined comfortable, slow, and fast walking speeds. Positions and kinematics of the pelvis and lower extremities were measured using a 3-dimensional video-based motion analysis system. MAIN OUTCOME MEASURES: Peak hip extension and anterior pelvic tilt. RESULTS: There were no statistically significant differences between the older and young adult groups during standing with respect to either hip extension (3 degrees +/-5 degrees vs 1 degrees +/-6 degrees) or anterior pelvic tilt (11 degrees +/-5 degrees vs 10 degrees +/-5 degrees). On the other hand, at comfortable walking speeds, the older adult group had reduced peak hip extension (7 degrees +/-6 degrees vs 11 degrees +/-6 degrees , P<.05) and increased anterior pelvic tilt (15 degrees +/-5 degrees vs 11 degrees +/-5 degrees) compared with the young adult group. At fast walking speeds, peak hip extension was significantly reduced in the older adult group than in the young adult group (9 degrees +/-6 degrees vs 14 degrees +/-6 degrees , P<.05), but there was no significant difference at slow walking speeds (6 degrees +/-6 degrees vs 9 degrees +/-5 degrees ). CONCLUSIONS: Age-related changes in gait defined by reduced peak hip extension and increased pelvic tilt are dynamic rather than standing postural characteristics.

Accidental Falls↗
PubMed2005

Effect of a gentle Iyengar yoga program on gait in the elderly: an exploratory study.

OBJECTIVE: To determine if a tailored yoga program could improve age-related changes in hip extension, stride length, and associated indices of gait function in healthy elders, changes that have been linked to increased risk for falls, dependency, and mortality in geriatric populations. DESIGN: Single group pre-post test exploratory study. A 3-dimensional quantitative gait evaluation, including kinematic and kinetic measurements, was performed pre- and postintervention. Changes over time (baseline to postintervention) in primary and secondary outcome variables were assessed using repeated-measures analysis of variance. SETTING: Yoga exercises were performed in an academic medical center (group classes) and in the subjects' homes (yoga home-practice assignments). Pre- and postassessments were performed in a gait laboratory. PARTICIPANTS: Twenty-three healthy adults (age range, 62-83 y) who were naive to yoga were recruited; 19 participants completed the program. INTERVENTION: An 8-week Iyengar Hatha yoga program specifically tailored to elderly persons and designed to improve lower-body strength and flexibility. Participants attended two 90-minute yoga classes per week, and were asked to complete at least 20 minutes of directed home practice on alternate days. MAIN OUTCOME MEASURES: Peak hip extension, average anterior pelvic tilt, and stride length at comfortable walking speed. RESULTS: Peak hip extension and stride length significantly increased (F1,18=15.44, P<.001; F1,18=5.57, P=.03, respectively). We also observed a trend toward reduced average pelvic tilt (F1,18=4.10, P=.06); adjusting for the modifying influence of frequency of home yoga practice strengthened the significance of this association (adjusted F1,17=14.30, P=.001). Both the frequency and duration of yoga home practice showed a strong, linear, dose-response relationship to changes in hip extension and average pelvic tilt. CONCLUSIONS: Findings of this exploratory study suggest that yoga practice may improve hip extension, increase stride length, and decrease anterior pelvic tilt in healthy elders, and that yoga programs tailored to elderly adults may offer a cost-effective means of preventing or reducing age-related changes in these indices of gait function.

Accidental Falls↗
PubMed2005

Center of mass movement and energy transfer during walking in children with cerebral palsy.

OBJECTIVE: To gain insight into the mechanical inefficiencies of gait patterns used by children with spastic diplegia by analysis of center of mass (COM) movement and energy recovery. DESIGN: Prospective study using between-group measures to analyze differences between children with cerebral palsy (CP) and age-matched controls without CP. SETTING: Assessments were performed in a gait laboratory. PARTICIPANTS: Fifteen children with spastic diplegia and 6 age-matched controls without CP with a mean age of 9.7 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Gait data assessed included temporal-distance factors, COM vertical excursion, work done on the COM, and the percentage of energy transferred and relative phase between the potential and kinetic energy. RESULTS: Children with CP had a 33% smaller energy recovery factor than the controls (P<.001). They also had 60% greater COM vertical excursion (P<.02) and a poorer phasic relation between potential and kinetic energies (P<.02), both of which contributed to greater mechanical work performed (P<.003). CONCLUSIONS: Compared with the age-matched controls without CP, the children with CP were mechanically less efficient in their gait. Interventions that promote heel contact and roll over and greater knee stability to better utilize the kinetic energy of push-off could improve walking efficiency.

Biomechanical Phenomena↗
PubMed2004

Postural control: toe-standing versus heel-toe standing.

Toe-standing is observed in a number of populations who are able to stand without loss of balance and also those who have balance problems. Intuitively, individuals who stand on their toes are able to successfully regulate their whole body movement in order to keep themselves stable. Force platform data were collected for ten able-bodied subjects during three quiet standing postures, (a) heel-toe standing; (b) half-toe standing and (c) standing en demi pointe (full toe-standing). Differences in control mechanisms with each posture were compared using stabilogram diffusion analysis. During open-loop control (short-term), toe-standing is less stable than heel-toe standing (P<0.05). There is greater stochastic activity when toe-standing (P<0.05), suggesting that any short-term instability is being compensated for by an increase in muscle activity across the lower joints. During closed-loop control (long-term), there is no difference in mediolateral (ML) stochastic activity (increased activity has been linked to falls) between toe-standing and heel-toe standing. In addition, toe-standing is more stable than heel-toe standing (P< s0.05). Toe-standing, in and of itself, may not be responsible for balance problems in populations who compulsorily toe-stand.

Adult↗
PubMed2004

Effects of treadmill walking speed on lateral gastrocnemius muscle firing.

OBJECTIVE: To study the electromyographic profile--including ON, OFF, and peak timing locations--of the lateral gastrocnemius muscle over a wide range of walking speeds (0.5-2.1 m/sec) in healthy young adults. DESIGN: We studied gastrocnemius muscle-firing patterns using an electromyographic surface electrode in 15 healthy subjects ambulating on a treadmill at their normal walking speed and at three paced walking speeds (0.5, 1.8, and 2.1 m/sec). Initial heel contact was determined from a force-sensitive switch secured to the skin over the calcaneous. RESULTS: For all speeds, the gastrocnemius firing pattern was characterized by a main peak, occurring 40-45% into the gait cycle, that increased in amplitude with walking speed. Speeds of > or =1.3 m/sec produced a common electromyographic timing profile, when the profile is expressed relative to the stride duration. However, at 0.5 m/sec (a speed typical of individuals with upper-motor neuron lesions), the onset of gastrocnemius firing was significantly delayed by 3-6% of the gait cycle and was prolonged by 8-11% of the gait cycle. CONCLUSION: Many patients with upper motor neuron lesions (e.g., stroke and traumatic brain injury) walk at speeds much slower than those commonly described in the literature for normal gait. At the slow walking speed of 0.5 m/sec, we have measured noticeable changes in the electromyographic timing profile of the gastrocnemius muscle. Given the importance of appropriate plantar flexor firing patterns to maximize walking efficiency, understanding the speed-related changes in gastrocnemius firing patterns may be essential to gait restoration.

Adult↗
PubMed2003

Keep on your toes: gait initiation from toe-standing.

Gait initiation from toe-standing is common in patients with upper motor neurone (UMN) pathology as well as in able-bodied subjects during certain dance and athletic situations. It is unclear whether balance problems in patients who toe-walk are due to the underlying pathology, or due to initiating gait from toe-standing. The aim of this study was to compare the biomechanics of gait initiation from toe-standing to that from heel-toe standing in healthy able-bodied subjects. Data were collected for three seconds prior to, and three seconds after, a visual signal to initiate gait. Ground reaction force and centre of pressure (COP) data were collected with an AMTI force platform, and electromyographic and kinematic data were collected from each limb with a Vicon motion analysis system. When initiating gait from toe-standing, there was a smaller backward displacement of the COP compared to heel-toe standing. In addition, greater forward momentum was generated, and there was an increase in gastrocnemius, rectus femoris and biceps femoris muscle activity. There were no differences in COP displacement or momentum generated in the mediolateral direction for the two conditions. Thus, initiating gait from toe-standing allows one to generate greater amounts of forward momentum but not at the expense of generating excessive stance-side momentum. This may be an advantageous method of initiating movement for dancers and athletes in certain situations. This work also suggests that balance problems in patients with UMN pathology are likely due to the underlying pathology and are not due to initiating gait from toe-standing.

Acceleration↗
PubMed2003

Predicting peak kinematic and kinetic parameters from gait speed.

OBJECTIVE: The aim of this study is to assess the predictability of the relationships between gait speed and common peak sagittal plane parameters in order to provide a set of reference parameter values. DESIGN: Lower extremity biomechanical data were collected in 64 healthy adults while walking barefoot at his/her comfortable walking speed, then at self-selected fast, slow and very slow speeds. Twenty seven peak joint parameter values were plotted and regressed as a function of gait speed. DISCUSSION: While most parameters change with increasing gait speed, in general, the kinetic parameters had better predictability than the kinematic parameters. Most of the power parameters were found to have a quadratic relationship with gait speed. Of the moment parameters, four had a linear relationship with gait speed, while four had a quadratic one. These relationships shown in the tables and graphs here can be used as a reference for 'normal' gait parameter values.

Adult↗
PubMed2003

Aging, muscle activity, and balance control: physiologic changes associated with balance impairment.

Older adults demonstrate increased amounts of postural sway, which may ultimately lead to falls. The mechanisms contributing to age-related increases in postural sway and falls in the elderly remain unclear. In an effort to understand age-related changes in posture control, we assessed foot center-of-pressure (COP) displacements and electromyographic data from the tibialis anterior, soleus, vastus lateralis, and biceps femoris collected simultaneously during quiet-standing trials from elderly fallers, elderly non-fallers, and healthy young subjects. Both traditional measures of COP displacements and stabilogram-diffusion analysis were used to characterize the postural sway of each group. Regression analyses were used to assess the relationship between the COP measures and muscle activity. Elderly fallers demonstrated significantly greater amounts of sway in the anteroposterior (AP) direction and greater muscle activity during quiet standing compared with the young subjects, while elderly non-fallers demonstrated significantly greater muscle activation and co-activation compared with the young subjects. No significant differences were found between elderly fallers and elderly non-fallers in measures of postural sway or muscle activity. However, greater postural sway in both the AP and mediolateral (ML) directions and trends of greater muscle activity were found in those older adults who demonstrated lower scores on clinical measures of balance. In addition, short-term postural sway was found to be significantly correlated with muscle activity in each of these groups. This work suggests that high levels of muscle activity are a characteristic of age-related declines in postural stability and that such activity is correlated with short-term postural sway. It is unclear whether increases in muscle activity preclude greater postural instability or if increased muscle activity is a compensatory response to increases in postural sway.

Accidental Falls↗
PubMed2003

Effect of a hip flexor-stretching program on gait in the elderly.

OBJECTIVES: To test whether a reduction in peak hip extension during the terminal stance phase of walking in elderly compared with young adult subjects represents a hip flexor contracture impairment rather than some dynamic consequence and to test the hypothesis that stretching the hip flexors improves both static and dynamic peak hip extension, as well as other age-related gait changes about the ankle. DESIGN: A double-blinded, randomized, controlled trial. SETTING: Stretching exercises were performed in the subjects' homes. Pre- and postassessments were performed in a gait laboratory. PARTICIPANTS: Ninety-six healthy elderly individuals in 2 groups: treatment (n=47) and control (n=49). INTERVENTION: The treatment group received a 1-time instruction in hip flexor stretching, whereas the control group received a 1-time instruction in shoulder abductor stretching. Participants in each group were asked to perform stretching exercises on their own twice daily for 10 weeks. MAIN OUTCOME MEASURES: Static and dynamic peak hip extension, peak anterior pelvic tilt, and other peak kinematic and kinetic variables during the gait cycle. RESULTS: There was a modest improvement in static peak hip extension as measured by a goniometer within the treatment group (mean +/- standard deviation, 6.1 degrees +/-2.5 degrees to 7.7 degrees +/-3.6 degrees, P=.032) compared with no change in the control group. At comfortable walking speed, dynamic hip extension tended to increase in the treatment group (5.1 degrees +/-9.7 degrees to 7.1 degrees +/-8.0 degrees, P=.103) compared with no real change in the control group (5.3 degrees +/-8.9 degrees to 5.4 degrees +/-7.5 degrees, P=.928). Similarly, at fast walking speed, dynamic hip extension tended to increase in the treatment group (6.4 degrees +/-9.8 degrees to 8.4 degrees +/-8.0 degrees, P=.093) compared with no change in the control group. Changes in ankle kinematics and kinetics included a significant improvement in peak ankle plantarflexion and a tendency to improved ankle power generation. CONCLUSION: The static and dynamic trends to improvement in peak hip extension were of similar magnitude, suggesting that age-related reduction in peak hip extension during gait is the result of a static hip flexion contracture rather than a dynamic consequence. Additionally, age-related changes in ankle kinematics and kinetics may be secondarily related to hip flexion contracture impairment rather than impairment at the ankle per se. This study was limited by the exercises being unsupervised and relying on 1-time instruction. A more rigorous and supervised hip flexor-stretching exercise program may yield more substantial improvements in gait parameters.

Aged↗
PubMed2003

Men's shoes and knee joint torques relevant to the development and progression of knee osteoarthritis.

OBJECTIVE: To determine if men's dress shoes and sneakers increase knee joint torques and play the same role in the development and/or progression of knee osteoarthritis (OA) as women's high-heeled dress shoes. METHODS: Three-dimensional data regarding lower extremity torques and motion were collected during walking in 22 healthy men while (1) wearing dress shoes, (2) wearing sneakers, and (3) barefoot. Data were plotted and qualitatively compared; major peak values were statistically compared between conditions. RESULTS: The external knee varus torque in early stance was slightly greater with the dress shoes and sneakers, but this slight increase can be explained by the faster walking speed with shoes. No significant increases were found in any other of the sagittal, coronal, or transverse knee torques when walking with dress shoes and sneakers compared to barefoot. CONCLUSION: Men's dress shoes and sneakers do not significantly affect knee joint torques that may have relevance to the development and/or progression of knee OA.

Adult↗
PubMed2002

Noise-enhanced vibrotactile sensitivity in older adults, patients with stroke, and patients with diabetic neuropathy.

OBJECTIVE: To test the hypothesis that vibrotactile detection thresholds in older adults, patients with stroke, and patients with diabetic neuropathy can be significantly reduced with the introduction of mechanical noise. DESIGN: A randomized controlled study. SETTING: A university research laboratory. PARTICIPANTS: Twelve healthy elderly subjects (age range, 67-85y), 5 patients with stroke (age range, 24-64y), and 8 patients with diabetic neuropathy (age range, 53-77y). INTERVENTIONS: Each subject's detection thresholds (ie, minimum level of stimulus to be detected) for a vibrotactile stimulus without and with mechanical noise (ie, random vibration with a small intensity) were determined by using a 4-, 2-, and 1-stepping algorithm. The stimuli were applied to the fingertip and/or to the first metatarsal of the foot. MAIN OUTCOME MEASURE: Detection threshold for a vibrotactile stimulus. RESULTS: The detection threshold at the fingertip for the vibration stimulus with mechanical noise was significantly lower than that without mechanical noise for all 12 elderly subjects, for 4 of the 5 patients with stroke, and all 8 patients with diabetic neuropathy. For the 8 patients with diabetes, mechanical noise also significantly reduced the vibrotactile detection threshold at the foot. CONCLUSIONS: Reduced vibrotactile sensitivity in older adults, patients with stroke, and patients with diabetic neuropathy can be significantly improved with input mechanical noise. Noise-based techniques and devices may prove useful in overcoming age- and disease-related losses in sensorimotor function.

Adult↗
PubMed2002

Effectiveness of a lateral-wedge insole on knee varus torque in patients with knee osteoarthritis.

OBJECTIVES: To test whether a lateral-wedged insole, inclined at 5 degrees or 10 degrees, significantly reduces knee varus torque during walking in patients with knee osteoarthritis compared with both using no insole and with wearing nonwedged control insoles of the same material and average thickness. DESIGN: Patients with medial knee osteoarthritis were studied while they walked wearing their comfortable shoes (1) without an insole; (2) with a 5 degrees lateral wedge compared with a nonwedged, 3.175-mm (1/8-in) even-thickness control insole; and (3) with a 10 degrees lateral wedge compared with a nonwedged 6.35-mm ((1/4)-in) even-thickness control insole. SETTING: A gait laboratory with 3-dimensional motion analysis and force platform equipment. PARTICIPANTS: Fifteen patients with clinical and radiographic osteoarthritis of the medial compartment of 1 knee. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak external knee varus torques during the stance period of gait. Data regarding lower-extremity joint torques and motions were collected, and knee joint torques using the different insoles and wedges were compared by analysis of variance. RESULTS: Although responses varied among individuals, as a group, both the 5 degrees and 10 degrees lateral-wedge insoles significantly reduced the knee varus torque during walking compared with walking with no insole and walking with nonwedged 3.175-mm and 6.35-mm control insoles. Compared with no insole, the 5 degrees wedge reduced the peak knee varus torque values by about 6% and the 10 degrees wedge reduced the peaks by about 8%. Although there were no significant differences in speed of walking between the conditions, the 10 degrees wedge and 6.35-mm control insoles were associated with varying degrees of discomfort. CONCLUSION: Both wedge insoles are effective in reducing the varus torque during walking beyond what theoretically could be explained by a reduced walking speed or cushioning effect from the insole. These data imply that wedged insoles are biomechanically effective and should reduce loading of the medial compartment in persons with medial knee osteoarthritis. Although the effect of the 5 degrees wedge was smaller, it may be more comfortable than the 10 degrees wedge to wear inside one's own shoes.

Aged↗
PubMed2002

Gender differences in pelvic motions and center of mass displacement during walking: stereotypes quantified.

OBJECTIVES: A general perception that women and men walk differently has yet to be supported by quantitative walking (gait) studies, which have found more similarities than differences. Never previously examined, however, are pelvic and center of mass (COM) motions. We hypothesize the presence of gender differences in both pelvic obliquity (motion of the pelvis in the coronal plane) and vertical COM displacement. Quantifiable differences may have clinical as well as biomechanical importance. METHODS: We tested 120 subjects separated into four groups by age and gender. Pelvic motions and COM displacements were recorded using a 3-D motion analysis system and averaged over three walking trials at comfortable walking speed. Data were plotted, and temporal values, pelvic angle ranges, and COM displacements normalized for leg length were quantitatively compared among groups. RESULTS: Comparing all women to all men, women exhibited significantly more pelvic obliquity range (mean ISD): 9.4 +/- 3.5 degrees for women and 7.4 +/- 3.4 degrees for men (p = 0.0024), and less vertical COM displacement: 3.7 +/- 0.8% of leg length for women and 3.3 +/- 0.9% for men (p = 0.0056). CONCLUSIONS: Stereotypically based gender differences were documented with greater pelvic obliquity and less vertical COM displacement in women compared with men. It is unclear if these differences are the intrinsic result of gender vs. social or cultural effects. It is possible that women use greater pelvic motion in the coronal plane to reduce their vertical COM displacement and, thus, conserve energy during walking. An increase in pelvic obliquity motion may be advantageous from an energy standpoint, but it is also associated with increased lumbosacral motion, which may be maladaptive with respect to the etiology and progression of low back pain.

Adult↗
PubMedDate not supplied

Reduced quadriceps activation after lumbar paraspinal fatiguing exercise.

CONTEXT: Although poor paraspinal muscle endurance has been associated with less quadriceps activation (QA) in persons with a history of low back pain, no authors have addressed the acute neuromuscular response after lumbar paraspinal fatiguing exercise. OBJECTIVE: To compare QA after lumbar paraspinal fatiguing exercise in healthy individuals and those with a history of low back pain. DESIGN: A 2 x 4 repeated-measures, time-series design. SETTING: Exercise and Sport Injury Laboratory. PATIENTS OR OTHER PARTICIPANTS: Sixteen volunteers participated (9 males, 7 females; 8 controls and 8 with a history of low back pain; age = 24.1 +/- 3.1 years, height = 173.4 +/- 7.1 cm, mass = 72.4 +/- 12.1 kg). INTERVENTION(S): Subjects performed 3 sets of isometric lumbar paraspinal fatiguing muscle contractions. Exercise sets continued until the desired shift in lumbar paraspinal electromyographic median power frequency was observed. Baseline QA was compared with QA after each exercise set. MAIN OUTCOME MEASURE(S): An electric burst was superimposed while subjects performed a maximal quadriceps contraction. We used the central activation ratio to calculate QA = (F(MVIC)/[F(MVIC) + F(Burst)])* 100, where F = force and MVIC = maximal voluntary isometric contractions. Quadriceps electromyographic activity was collected at the same time as QA measurements to permit calculation of median frequency during MVIC. RESULTS: Average QA decreased from baseline (87.4% +/- 8.2%) after the first (84.5% +/- 10.5%), second (81.4% +/- 11.0%), and third (78.2% +/- 12.7%) fatiguing exercise sets. On average, the group with a history of low back pain showed significantly more QA than controls. No significant change in quadriceps median frequency was noted during the quadriceps MVICs. CONCLUSIONS: The quadriceps muscle group was inhibited after lumbar paraspinal fatiguing exercise in the absence of quadriceps fatigue. This effect may be different for people with a history of low back pain compared with healthy controls.

Journal Article↗