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Biomedical subjects

Bernadette Murphy

Publications and source records attributed to Bernadette Murphy.

8 recordsLinked to original sources
PubMed2006

Cervical spine manipulation alters sensorimotor integration: a somatosensory evoked potential study.

OBJECTIVE: To study the immediate sensorimotor neurophysiological effects of cervical spine manipulation using somatosensory evoked potentials (SEPs). METHODS: Twelve subjects with a history of reoccurring neck stiffness and/or neck pain, but no acute symptoms at the time of the study were invited to participate in the study. An additional twelve subjects participated in a passive head movement control experiment. Spinal (N11, N13) brainstem (P14) and cortical (N20, N30) SEPs to median nerve stimulation were recorded before and for 30min after a single session of cervical spine manipulation, or passive head movement. RESULTS: There was a significant decrease in the amplitude of parietal N20 and frontal N30 SEP components following the single session of cervical spine manipulation compared to pre-manipulation baseline values. These changes lasted on average 20min following the manipulation intervention. No changes were observed in the passive head movement control condition. CONCLUSIONS: Spinal manipulation of dysfunctional cervical joints can lead to transient cortical plastic changes, as demonstrated by attenuation of cortical somatosensory evoked responses. SIGNIFICANCE: This study suggests that cervical spine manipulation may alter cortical somatosensory processing and sensorimotor integration. These findings may help to elucidate the mechanisms responsible for the effective relief of pain and restoration of functional ability documented following spinal manipulation treatment.

Adult↗
PubMed2006

Changes in the flexion relaxation response following an exercise intervention.

STUDY DESIGN: Pre and post 12-week training study using surface electromyography to measure the flexion relaxation response. OBJECTIVE: To evaluate whether the active or passive phases of the flexion relaxation measurement changes following an exercise intervention in patients with low back pain. SUMMARY OF BACKGROUND DATA: Impaired neuromuscular activation is an area of specific interest in patients with chronic nonspecific low back pain (LBP). The flexion relaxation phenomenon is commonly measured in LBP patients; however, there is insufficient evidence about the changes in this measure following an intervention. METHODS: Fifteen subjects with chronic LBP (7 females, 8 males) performed a 12-week training intervention. The main outcome measures were the Oswestry disability index, visual analog scale, and flexion relaxation response analyzed by the raw electromyograph (EMG) signal, the relative EMG signal, and the flexion relaxation ratio. RESULTS: Disability and pain scores improved significantly after the 12-week intervention. There were no changes in the active components of the flexion relaxation measurement but an approximate 67% decrease in the amount of activity measured during the relaxation phase at full trunk flexion. CONCLUSION: The data suggest that afferent feedback changes may be explaining why there is improved electrical relaxation following an exercise intervention.

Adult↗
PubMed2006

The relationship between active and neural measures in patients with nonspecific low back pain.

STUDY DESIGN: Cross-sectional study of 50 individuals with nonspecific low back pain (LBP). OBJECTIVE: To evaluate the relationship between active and neural measurements in individuals with nonspecific LBP. SUMMARY OF BACKGROUND DATA: The Panjabi model for spinal stability consists of 3 interacting subsystems. Specific musculoskeletal measurements can be identified within the active and neural systems. The relationships among measures within this model have not been identified. METHODS: A total of 50 individuals with nonspecific LBP were evaluated for measures of the active and neural stability systems, and analyzed using a canonical correlation analysis, which is used to measure the relationship between 2 multidimensional variables. RESULTS: There were 2 significant relationships identified. The first identified a relationship among fatigue, flexion relation, and the feedforward abdominal response (r = 0.764, P < 0.001). The second relationship was between the Sorenson endurance test and feedforward abdominal response (r = 0.697, P = 0.006). CONCLUSION: Identification of relationships between back pain measurements may allow discrimination between individuals with different histology and pain levels. This process may assist the specificity of treatment programs prescribed for patients with back pain.

Abdominal Muscles↗
PubMed2006

Changes in muscle activity and perceived exertion during exercises performed on a swiss ball.

The objective of this study was to determine differences in electromyographic (EMG) activity of prime mover and abdominal muscles while performing squats, push ups, and double leg lowering with a swiss ball. Twelve healthy subjects performed the movements. There was no difference between the surface conditions for muscle activity during the squat exercise; however, individuals had lower perceived exertion for the swiss ball squat. Activity of the triceps and abdominals was highest performing push ups on the swiss ball, whereas the activity of rectus abdominus (RA) only increased during double leg lowering on the swiss ball. Perceived exertion was highest for the push up and leg-lowering exercise performed on the swiss ball. Increased RA activity during double leg lowering can be attributed to its role as a hip flexor, whereas the lack of a rotation aspect to the task prevented increased oblique muscle activity. The swiss ball appears to only increase muscle activity during exercises where the unstable surface is the primary base of support.

Adult↗
PubMed2002

Intramuscular sensation in conscious human subjects: a qualitative and quantitative study utilizing signal detection theory methodology.

To investigate whether human subjects could consciously perceive different levels of intramuscular sensation, EMG needle electrodes were inserted into the forearm extensor musculature. Qualitative descriptions of the types of sensations evoked at various current intensities were recorded. A series of preliminary experiments was performed in order to determine the optimum waveform, current intensity, duration and separation between adjacent current pairs that could reliably be discriminated by conscious human subjects. The methodology of signal detection theory was utilized to obtain the discrimination measure, d' (d prime). Values of d' were obtained for sequential blocks of trials consisting of randomly delivered blocks of 50 "strong" and 50 "weak" stimuli. The ability to discriminate both noxious and non-noxious stimuli was determined using d'. It was demonstrated that human subjects are able to qualitatively describe non-nociceptive sensations elicited by low levels of intramuscular stimulation. Subjects were able to reliably discriminate pairs of electrical stimuli separated in intensity by 0.4 dB over four sequential blocks of trials on the same day and on different days. This work demonstrates that signal detection theory methods can reliably measure sensory discrimination in skeletal muscle, for both noxious and non-noxious levels of electrical stimulation. A protocol is proposed for appropriate future use of this methodology to investigate alterations in muscle sensation following experimental interventions.

Adult↗
PubMed2002

The effects of repetitive contractions and ischemia on the ability to discriminate intramuscular sensation.

In order to investigate whether repetitive, low-level, muscular contractions or ischemia affect the ability of subjects to discriminate electrical stimuli delivered to the forearm musculature, a total of 25 experiments was performed on a group of five healthy subjects utilizing signal detection methodology. EMG needle electrodes were inserted into the forearm extensor musculature and the discriminability of two different pairs of constant current electrical stimuli were measured for sequential blocks of 100 trials, before and after the experimental interventions. Repetitive muscular activity consisting of a 15-min typing intervention at a rate of 60-80 wpm using a numeric keypad led to a significant decrease in the ability to discriminate the non-noxious stimulus pair in the block of trials immediately following the typing intervention, which then returned to pre-intervention discrimination levels following a 5-min break. The forearm ischemia significantly impaired the ability to discriminate both the noxious and non-noxious stimulus pair in the blocks of trials during and immediately after ischemia, which then returned to pre-intervention discrimination levels following a 5-min break. These experiments demonstrate that both repetitive muscular activity and ischemia acutely decrease the ability to discriminate intramuscular sensation. The mechanism may be due to decreased cortical processing, spinal cord sensitization or peripheral ischemia of large diameter afferents. These findings may be relevant to the physiological mechanisms underlying the development of overuse injuries.

Adult↗
PubMedDate not supplied

The effect of sacroiliac joint manipulation on feed-forward activation times of the deep abdominal musculature.

OBJECTIVES: To determine the incidence of delayed feed-forward activation (FFA) times in a group of healthy young males; to retest those subjects who showed delayed FFA after 6 months to determine the reliability of the measure in the absence of treatment or injury in the intervening period; and to determine the effect of sacroiliac joint manipulation on delayed FFA times. METHODS: Ninety young males were assessed for the FFA of their deep abdominal muscles in relation to rapid upper limb movements. Those who met the criteria for delayed FFA (failure of deep abdominal activation within 50 milliseconds of deltoid activation) were then reassessed 6 months later. These subjects then underwent sacroiliac joint manipulation on the side demonstrating decreased joint movement during hip flexion and lateral flexion. Feed-forward activation times were then reassessed after joint manipulation. RESULTS: Seventeen (18.9%) of 90 subjects met the criteria of impaired FFA. Thirteen of 17 were available to be remeasured at 6-month follow-up. The intraclass correlation coefficient for FFA at this time was greater than 0.70 for all movement directions. There was a significant improvement (38.4%) in FFA times for this group when remeasured immediately after the sacroiliac joint manipulation. CONCLUSIONS: Delayed FFA is a highly reproducible measure at long-term follow-up. This technique appears to be a sensitive marker of the neural effects of sacroiliac joint manipulation. Future prospective studies are needed to determine if delayed FFA times are a marker for those at risk for developing back pain.

Abdominal Muscles↗