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Muscle Power (muscle + power)

Distribution by Scientific Domains

Medical Sciences	90%

Selected Abstracts

Bradykinesia, muscle weakness and reduced muscle power in Parkinson's disease,

MOVEMENT DISORDERS, Issue 9 2009
Natalie E. Allen BAppSc (Physio) Hons
Abstract Muscle power (force × velocity) could clarify the relationship between weakness and bradykinesia in Parkinson's disease (PD). The aims of this study were to determine if patients with PD were weaker and/or less powerful in their leg extensor muscles than a neurologically normal control group and to determine the relative contributions of force and movement velocity/bradykinesia to muscle power in PD. Forty patients with PD and 40 controls were assessed. Strength in Newtons (N) was measured as the heaviest load the participant could lift. Power in Watts (W) was measured by having the participant perform lifts as fast as possible. The PD group were 172 N weaker (95% CI 28,315) and 124 W less powerful at peak power (95% CI 32,216) than controls. However, velocity at maximal power was only reduced compared with controls when lifting light to medium loads. When lifting heavy loads bradykinesia was no longer apparent in the PD group. These results suggest that reduced muscle power in PD at lighter loads arises from weakness and bradykinesia combined, but at heavier loads arises only from weakness. The absence of bradykinesia in the PD group when lifting heavy loads warrants further investigation. © 2009 Movement Disorder Society [source]

Ventilatory control in humans: constraints and limitations

EXPERIMENTAL PHYSIOLOGY, Issue 2 2007
Susan A. Ward
Below the lactate threshold (,L), ventilation responds in close proportion to CO2 output to regulate arterial partial pressure of CO2. While ventilatory control models have traditionally included proportional feedback (central and carotid chemosensory) and feedforward (central and peripheral neurogenic) elements, the mechanisms involved remain unclear. Regardless, putative control schemes have to accommodate the close dynamic ,coupling' between and . Above ,L, is driven down to constrain the fall of arterial pH by a compensatory hyperventilation, probably of carotid body origin. When requirements are high (as in highly fit endurance athletes), can attain limiting proportions. Not only does this impair gas exchange at these work rates, but there may be an associated high metabolic cost for generation of respiratory muscle power, which may be sufficient to divert a fraction of the cardiac output away from the muscles of locomotion to the respiratory muscles, further compromising exercise tolerance. [source]

Dermatomyositis presenting as panniculitis

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 2 2000
Yen-Yu Chao MD
A 44-year-old obese woman was transferred to our clinic with a diagnosis of panniculitis. Examination showed multiple, indurated, erythematous, painful nodules and plaques distributed on the shoulders, back, forechest, abdomen, buttock, and bilateral thighs. These skin lesions appeared 2 months previously, measured 5,8 cm, and were tender on palpation. No obvious inducing factor was traced. The lesions seemed unresponsive to treatment with nonsteroidal anti-inflammatory drugs (ibuprofen, 400 mg three times a day) as similar lesions appeared in subsequent visits. Progressive proximal muscle weakness was found 1 month later. She was then admitted via the emergency room because of extensive painful skin plaques and abdominal pain. Diffuse erythematous to violaceous swelling of the face, neck, and shoulder was noted at about the same time ( Fig. 1). A skin biopsy specimen from the nodular lesion showed poikilomatous epidermal changes ( Fig. 2), and marked mononuclear cell infiltration in the dermis and subcutaneous fat ( Fig. 3). Dermatomyositis was considered as the diffuse violaceous facial erythema could be a form of heliotrope eruption, but Gottron's papule was not found. At admission, serum creatinine phosphokinase (CPK) was mildly elevated (436 IU/L; normal range, 20,170 IU/L), but serum asparagine transaminase (AST) and lactate dehydrogenase (LDH) levels were within normal limits (36 IU/L; normal, 11,47 IU/L; and 108 IU/L; normal, 90,280 IU/L, respectively). Antinuclear antibody was 1 : 80 positive with an atypical speckled pattern. Muscle strength was weakest during the first 2 days, about grade 3 by the Medical Research Council (MRC) of Great Britain scale. Gower's sign was positive. An electromyogram showed myopathic changes and a nerve conduction velocity study was normal. Serum enzymes were elevated further on the third day: AST, 55 IU/L; CPK, 783 IU/L with 100% MM form. The diagnosis of dermatomyositis was established. As for the work-up result, anti-dsDNA antibody, anti-ENA antibody, and anti-Jo1 antibody were negative. Tumor marker screen (,-HCG, AFP, CEA, and CA-125), was negative, and rhinolaryngopharyngoscope examination and gynecologic sonography were normal. Figure 1. Diffuse erythematous swelling with subtle violaceous hue extending from the temporal area to the cheeks, neck, and shoulders. The crusted lip ulcers of herpes simplex were also noted Figure 2. Basketweave hyperkeratosis, mild acanthosis, subtle vacuolar degeneration of the basal cells, and melanin incontinence (hematoxylin and eosin, ×400) Figure 3. Heavy mononuclear cells infiltrated in the subcutaneous fat tissue (hematoxylin and eosin, ×100) Pancreatitis was initially suspected because of epigastric pain and tenderness, elevated serum lipase (382 U/L; normal, 23,200 U/L), and amylase (145 U/L; normal, 35,118 U/L). No evidence of pancreatitis could be found in abdominal sonography and abdominal computed tomography (CT), however. The epigastric pain and tenderness subsided soon after admission and the serum pancreatic enzyme level declined on the second day (amylase 69 U/L; lipase, 276 U/L). The patient was then diagnosed with dermatomyositis and treated with prednisolone (120 mg/day). CPK dropped dramatically from 3286 IU/L the day before treatment to 1197 IU/L 3 days after. Panniculitis lessened and the muscle power improved after 1 week of treatment. The disease activity fluctuated even with treatment with prednisolone and the patient often felt listless and weak. The muscle weakness sometimes deteriorated to affect the patient's mobility. Facial erythema and panniculitis-like lesions were found during the worse times. Methotrexate and azathioprine were then added (7.5 mg and 250 mg per week, respectively), but CPK was still mildly elevated (189 IU/L), and the patient still felt ill. Human immune globulin (5%, 500 mL per day, 5 days per month) intravenous infusion was initiated thereafter. There was a dramatic response. Full muscle strength was retained and CPK was within the normal range in the following 6 months with only immune globulin therapy. [source]

Weighted Stair Climbing in Mobility-Limited Older People: A Pilot Study

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 4 2002
MD Jonathan Bean MS
OBJECTIVES: To evaluate weighted stair climbing exercise (SCE) as a means of increasing lower extremity muscle power in mobility-limited older people. DESIGN: Single-blinded, randomized controlled pilot study INTERVENTIONS: Subjects were randomized into one of two 12-week exercise programs. The intervention group (SCE) (n = 23) ascended and descended stairs, at a set pace, while wearing a weighted vest. The control group (WALK) (n = 22) participated in a standardized walking program. MEASUREMENTS: Primary and secondary outcomes included measures of muscle power and strength, submaximal aerobic capacity, and physical performance. RESULTS: SCE produced 17% improvement in double leg press peak power in comparison with WALK (P = .013) and significant improvement in stair climbing power from baseline (12%). Improvement in submaximal aerobic performance was equivalent for both groups. Although not statistically significant, effect size estimates suggest that SCE can potentially influence knee extension power and strength. Stair climb time was improved in both groups, whereas SCE produced significant improvements from baseline SPPB score in a subcohort of participants. CONCLUSIONS: These findings suggest that SCE may be a useful component of a home exercise program designed to enhance lower extremity muscle power, aerobic capacity, and functional performance. Further investigation is needed involving larger sample sizes and direct comparisons with other forms of resistance training. [source]

Bradykinesia, muscle weakness and reduced muscle power in Parkinson's disease,

Capsaicin delays regeneration of the neuromuscular junction of rat extensor digitorum longus muscle after ischemia

MUSCLE AND NERVE, Issue 4 2006
Béla Turchányi MD
Abstract Trauma or the tourniquet used in orthopedic surgery is often associated with ischemia,reperfusion (I/R) injury with a consequent decrease of muscle power. To explore whether components of the neuromuscular junction (NMJ) are involved in this muscle dysfunction, NMJs were ultrastructurally characterized in the extensor digitorum longus muscle of rats at reperfusion times of 1, 24, 72, and 168 h after a 120-min arterial occlusion. Disorganization of the presynaptic membrane and mitochondrial injury was noted at 1 h, followed by fragmentation and partial engulfment of nerve terminals by Schwann cells at 24 and 72 h. The magnitude of degenerative changes declined at 168 h, suggesting the commencement of regeneration. The postsynaptic membrane remained intact throughout the whole period. In our previous study, deafferentation with pretreatment of the sciatic nerve with capsaicin, which reduces neurogenic inflammation and has a selective effect on nociceptive fibers, improved functional recovery of the muscle after I/R. The present results document a significantly delayed structural regeneration of the motor nerve terminals after combined capsaicin and I/R treatment. Since capsaicin treatment alone had no discernible effect on the structure of NMJs, the findings point to a possibly indirect effect of capsaicin on the motor nerves, which may predispose them to increased susceptibility unmasked only by a subsequent injury. The mismatch between the enhanced functional improvement of the muscle and delayed regeneration of the nerve after capsaicin pretreatment questions the efficient use of such deafferentation to protect the integrity of neuromuscular junctions in I/R injury. Muscle Nerve, 2006 [source]

Maximal explosive muscle power in obese and non-obese prepubertal children

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 3 2009
Stefano Lazzer
Summary Objective:, The objectives of the present study was to compare the maximal explosive muscle power developed by the lower limbs in obese and non-obese prepubertal children. Design:, Twenty-five obese [mean body mass index (BMI) z -score: 2·4] and 30 non-obese (mean BMI z -score: 0) children aged 8,12 years, participated in this study. Body composition was measured by bioelectrical impedance analysis and the maximal explosive power of the lower limbs was assessed by the Exercise-Ergometer (a sledge dynamometer). Results:, Absolute peak force (Fpeak) was higher in obese than in non-obese children by 18·2% (P<0·001). Peak speed (vpeak) was not significantly different between groups (P = 0·504). Consequently, absolute peak power (W,peak) was higher in obese than in non-obese children (+19·3%, P = 0·021). Considering gender differences, absolute Fpeak and vpeak were higher in boys than in girls by +12·3 and +17·4% (P<0·05), respectively, thus yielding higher absolute W,peak values in boys as compared to girls (+26·1%, P<0·001). Finally, W,peak normalized for fat-free mass (FFM) was not different between obese and non-obese children but higher in boys than in girls (+24·5%, P<0·001). Conclusions:, Power generation capability per unit of FFM was similar between obese and non-obese children but was significantly higher in boys than girls. On the clinical practice it seems important to devote supplementary care to sustain and improve the motor function of obese and non-obese girls. [source]