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Biomedical subjects

M V Hurley

Publications and source records attributed to M V Hurley.

13 recordsLinked to original sources
PubMed2002

Exercise can reverse quadriceps sensorimotor dysfunction that is associated with rheumatoid arthritis without exacerbating disease activity.

OBJECTIVES: To compare quadriceps sensorimotor function, lower limb functional performance and disability in patients with rheumatoid arthritis (RA) and healthy subjects, and to investigate the efficacy and safety of a brief rehabilitation regime. METHODS: Quadriceps strength, voluntary activation, proprioceptive acuity and the aggregate time [aggregate functional performance time (AFPT)] taken to perform four common activities [aggregate functional performance time (AFPT)] were compared between 103 RA patients who had lower limb involvement and 25 healthy subjects. In addition, disability (Health Assessment Questionnaire), clinical disease activity and the plasma concentration of proinflammatory cytokines were measured in the RA patients. In a follow-on randomized controlled trial of rehabilitation, these variables were used as baseline data for 93 of the RA patients, who were randomized to a rehabilitation or a control group. Changes in the variables were analysed within and between groups. RESULTS: Compared with healthy subjects, RA patients had weaker quadriceps [mean difference 157 N; 95% confidence interval (CI) 125-189], poorer activation (8%, 95% CI 4.5-15) and proprioceptive acuity (0.8 degrees, 95% CI 0.4-1.3) and took longer to perform the AFPT (34 s, CI 23.5-44.8). Rehabilitation increased quadriceps strength (mean increase 61 N, 95% CI 28-95) and voluntary activation (8%, 95% CI 3-12.4) and decreased the AFPT (12.3 s, 95% CI -2 to 27.7) and subjective disability (0.21 HAQ points, 95% CI 0-0.35) without exacerbating disease activity. All the improvements were maintained at the 6-month follow-up. There was no change during the control period. CONCLUSIONS: Patients with RA that affected their lower limb had quadriceps sensorimotor deficits that were associated with lower limb disability. A clinically applicable rehabilitation regime increased quadriceps sensorimotor function and decreased lower limb disability without exacerbating pain or disease activity. For patients with well-controlled RA that causes lower limb involvement, the regime is effective and safe.

Adult↗
PubMed2002

Neuromuscular and psychomotor function in elderly subjects who fall and the relationship with vitamin D status.

Vitamin D and calcium supplementation significantly reduces the incidence of fractures. Evidence suggests vitamin D deficiency impairs neuromuscular function, causing an increase in falls and thereby fractures. The relationship between vitamin D, functional performance, and psychomotor function in elderly people who fall was examined in a prospective cross-sectional study. Patients were recruited from a falls clinic and stratified according to serum 25-hydroxyvitamin-D levels (25OHD): group 1, 25OHD < 12 microg/liter; group 2 25OHD, 12-17 microg/liter; and group 3, 25OHD > 17 microg/liter. Healthy elderly volunteers with 25OHD > 17 microg/liter comprised group 4 (n = 20/group). Measures included aggregate functional performance time (AFPT, seconds), isometric quadriceps strength (Newtons), postural sway (degrees), and choice reaction time (CRT, seconds). Serum bone biochemistry, 25OHD, and parathyroid hormone levels were measured. Patients who fell had significantly impaired functional performance, psychomotor function, and quadriceps strength compared with healthy subjects (AFPT: 51.0 s vs. 32.8 s,p < 0.05; CRT: 1.66 s vs. 0.98 s,p < 0.05; strength: 223N vs. 271N, t = 2.35, p = 0.02). Group 1 had significantly slower AFPT (66.0 s vs. 44.8 s, t = 4.15, p < 0.05) and CRT (2.37 s vs. 0.98 s, t = 3.59, p < 0.05) than groups 2 and 3. Group 1 had the greatest degree of postural sway and the weakest quadriceps strength, although this did not reach significance. Multivariate analysis revealed 25OHD as an independent variable for AFPT, CRT, and postural sway. PTH was an independent variable for muscle strength. Older people who fall have impaired functional performance, psychomotor function, and muscle strength. Within this group, those with 25OHD < 12 microg/liter are the most significantly affected.

Accidental Falls↗
PubMed1999

The role of muscle weakness in the pathogenesis of osteoarthritis.

To date, very few studies have investigated the role of muscle dysfunction in the pathogenesis of osteoarthritis (OA). Using largely indirect evidence, this article hypothesizes that motor and sensory dysfunction of muscle may be important factors in the pathogenesis of articular damage and are not simply a consequence of joint damage. A new paradigm is constructed to better describe the complex interrelationship between muscle sensorimotor dysfunction, joint damage, and disability in OA. If the hypothesis is correct, because muscle is a relatively plastic tissue, maintaining well-conditioned muscles may delay or prevent the onset of OA, and rehabilitation exercise therapy that reverses muscle sensorimotor dysfunction may ameliorate the effects of OA.

Humans↗
PubMed1998

Quadriceps function, proprioceptive acuity and functional performance in healthy young, middle-aged and elderly subjects.

BACKGROUND: Muscle functions to generate force-producing movement and also has a role in proprioception. If ageing compromises these sensorimotor functions of muscle, the ability of older subjects to detect and correct postural sway may be impeded, resulting in impairment of functional performance. METHOD: To see if age-related changes occurred and, if so, what their effects might be. Quadriceps strength, proprioception, postural stability and functional performance were assessed in young (n = 20, mean age 23 years), middle-aged (n = 10, mean age 56 years) and elderly (n = 15, mean age 72 years) subjects. RESULTS: With increasing age there were decreases in quadriceps strength (r = -0.511; P < 0.001), acuity of joint position sense (r = -0.603; P < 0.001) and postural stability (ANOVA < 0.002) during stance conditions which placed a greater reliance on muscle proprioceptors. These changes may decrease postural stability confidence, resulting in impaired performance of common activities of daily living (r = 0.635; P < 0.001). CONCLUSIONS: The age-related deterioration in sensorimotor function of muscle may contribute to the increased fear and frequency of falls in elderly subjects, thereby decreasing independence.

Accidental Falls↗
PubMed1998

Improvements in quadriceps sensorimotor function and disability of patients with knee osteoarthritis following a clinically practicable exercise regime.

OBJECTIVE: Quadriceps sensorimotor dysfunction may be important in the pathogenesis of knee osteoarthritis (OA) and a determinant of disability. Exercise regimes can increase quadriceps strength, but whether this improves proprioception and reduces disability is uncertain. Moreover, research regimes involve protracted treatment which is clinically impracticable. METHODS: We compared quadriceps sensorimotor function and disability in 60 patients with knee OA, before and after an exercise regime, with a control group (n = 37) who did not exercise. RESULTS: Exercise improved quadriceps strength (mean change, 95% CI; 73 N, 26-19 N), voluntary activation (14%, 5-20%), knee joint position sense (0.6 degrees, 0.1-1.8 degrees), and reduced the Lequesne Index (3.5, 0.5-4) and aggregate time of four activities of daily living (8.4 s, 0.2-16.7 s). At 6 month follow-up, these improvements were maintained. The parameters of the control group were unchanged. CONCLUSIONS: These results substantiate the association between quadriceps sensorimotor dysfunction and disability, emphasizing the importance of quadriceps exercise in the management of knee OA. The regimen is relatively brief and clinically practicable, but could be adapted to make it more cost effective.

Adult↗
PubMed1998

Quadriceps weakness in osteoarthritis.

Involvement of the quadriceps muscle group in knee osteoarthritis is receiving increasing research interest. The motor and sensory functions of muscle are intimately linked, and deficits in the sensorimotor functions of the quadriceps have been identified and proposed as possible factors in the pathogenesis of knee osteoarthritis or as consequences of the disease. Weakness of the quadriceps as a clinical feature of knee osteoarthritis has been well recognized for some time, but causes for this weakness and its significance as a determinant of the patient's disability is only now being investigated. Rehabilitation regimens that increase quadriceps weakness also effect improvements in the patient's disability, but the length and cost most of these research regimens would be impractical in the clinical setting. More clinically practicable rehabilitation regimens need to be devised that could be implemented in the community, if the management of this chronic, prevalent condition is to be managed effectively and cost-effectively.

Disability Evaluation↗
PubMed1997

Sensorimotor changes and functional performance in patients with knee osteoarthritis.

OBJECTIVE: Muscles are essential components of our sensorimotor system that help maintain balance and perform a smooth gait, but it is unclear whether arthritic damage adversely affects muscle sensorimotor function. Quadriceps sensorimotor function in patients with knee osteoarthritis (OA) was investigated, and whether these changes were associated with impairment of functional performance. METHODS: Quadriceps strength, voluntary activation, and proprioceptive acuity (joint position sense acuity) were assessed in 103 patients with knee OA and compared with 25 healthy control subjects. In addition, their postural stability, objective functional performance (the aggregate time for four activities of daily living), and disabilities (lequesne index) were also investigated. RESULTS: Compared with the control subjects, the patients with knee OA had weaker quadriceps (differences between group mean 100N, CI 136, 63N), poorer voluntary activation (20% CI 13, 25%) that was associated with quadriceps weakness, and impaired acuity of knee joint position sense (1.28 degrees, CI 0.84, 1.73 degrees). As a group the patients were more unstable (p = 0.0017), disabled (10, CI 7, 11), and had poorer functional performance (19.6 seconds, CI 14.3, 24.9 seconds). The most important predictors of disability were objective functional performance and quadriceps strength. CONCLUSIONS: In patients with knee OA, articular damage may reduce quadriceps motoneurone excitability, which decreases voluntary quadriceps activation thus contributing to quadriceps weakness, and diminishes proprioceptive acuity. The arthrogenic impairment in quadriceps sensorimotor function and decreased postural stability was associated with reduced functional performance of the patients.

Activities of Daily Living↗
PubMed1994

An evaluation of different protocols for measuring the force-velocity relationship of the human quadriceps muscles.

A modified Cybex II isokinetic dynamometer was used to evaluate the problems associated with measuring the concentric force-velocity characteristics of human knee extensor muscles. Three contraction protocols were investigated, simple voluntary contractions (VC); releases from maximal voluntary isometric contractions (VR) and releases from isometric femoral nerve stimulated contractions (FNR). Percutaneous stimulation of the quadriceps was unsuitable for dynamic contractions as the proportion of the muscle activated varied with the angle of knee flexion. Isometric length-tension relationships and isokinetic contractions at seven angular velocities between 0.5 and 5.2 rad.s-1 were recorded in five subjects. During isometric and slow dynamic contractions the voluntary forces were often greater than those obtained by femoral nerve stimulation, probably due to subjects stretching the rectus femoris during voluntary manoeuvres. It was found that the VC protocol produced acceptable isokinetic force recordings only at velocities below 3.1 rad.s-1 in most subjects whilst VR contractions resulted in unexpectedly low forces at velocities below 1.57 rad.s-1. Of the three techniques employed, FNR, although uncomfortable for subjects, provided the most accurate and reliable method of measuring force-velocity characteristics of knee extensor muscles. FNR contractions produced a force-velocity curve which showed a smooth decline in force with increasing velocity up to 5.2 rad.s-1. VC contractions appear to be an acceptable alternative for testing the muscles provided the angular velocity is less than 3.1 rad.s-1 and the subjects can be prevented from stretching the rectus femoris during the movement.

Adult↗
PubMed1994

Arthrogenic quadriceps inhibition and rehabilitation of patients with extensive traumatic knee injuries.

1. The relationship between joint damage, quadriceps weakness and arthrogenic muscle inhibition was investigated in eight patients who had sustained extensive traumatic knee injury. Isometric and isokinetic quadriceps and hamstring voluntary strength, and quadriceps arthrogenic muscle inhibition during isometric contractions, were measured before and after 4 weeks (approximately 100 h) of intensive rehabilitation. 2. Compared with the uninjured leg, before rehabilitation the injured leg had larger amounts of quadriceps arthrogenic muscle inhibition (P < 0.025), quadriceps (P < 0.0001) and hamstring (P < 0.0001) weakness and severe functional joint instability. There was a negative correlation between the amount of arthrogenic muscle inhibition and quadriceps voluntary contraction force (P < 0.025). 3. After rehabilitation in the injured leg there were small hamstring strength increases (P < 0.05-0.025), but no overall significant quadricep strength increase. Arthrogenic muscle inhibition was statistically unchanged. Severe functional joint instability was still reported by all patients. 4. Previous studies have shown that minimal joint damage evokes relatively less arthrogenic muscle inhibition that does not impede rehabilitation. These data indicate that greater joint damage is associated with greater arthrogenic muscle inhibition, quadriceps weakness and joint instability. Furthermore, intensive rehabilitation had little affect on either quadriceps arthrogenic muscle inhibition or atrophy.

Adult↗
PubMed1993

The influence of arthrogenous muscle inhibition on quadriceps rehabilitation of patients with early, unilateral osteoarthritic knees.

Reflex arthrogenous muscle inhibition (AMI) may cause muscle atrophy or impede effective rehabilitation of affected muscle groups. To investigate this, bilateral quadriceps AMI, isometric and isokinetic muscle strength were measured in 10 patients with unilateral osteoarthritic knees, before and after a course of routine physiotherapy. Before rehabilitation, quadriceps of all the diseased legs were inhibited (P < 0.05) and 40% weaker (P < 0.02) than the non-diseased legs. Following rehabilitation, AMI decreased (P < 0.01) in the diseased leg and strength increased at all test velocities (P < 0.05-0.005); however, strength deficits compared with the non-diseased leg remained. Subjective improvements in functional ability and confidence in the diseased leg were reported. Though AMI may be partially responsible for unilateral muscle weakness, it does not preclude strength gain in affected muscles. Possible physiological mechanisms which evoke AMI may also adversely affect muscle proprioception, implicating AMI as a possible cause of initiation or progression of degenerative joint disease.

Adult↗