Early alterations in serum creatine kinase and total cholesterol following high intensity eccentric muscle actions

Aim. The purpose of this experiment was to assess the levels of muscle soreness, serum total cholesterol (TC) and creatine kinase (CK) in the first 48 hours following fatiguing eccentric exercise performed with the triceps brachii. Methods. Eleven untrained male college students performed a total of 50 eccentric elbow extensions in 8 sets (6x7 and 2x4) with a load equal to 85% of their maximal concentric elbow extension strength. Isometric elbow extension strength, muscle soreness and circumference, and serum CK and TC concentrations were measured before, immediately after, and 2, 24 and 48 hours after the exercise. Results. Statistically reliable changes in isometric strength, serum CK and TC, muscle soreness and upper arm circumference occurred within the first 48 hours following eccentric exercise. Serum TC concentrations exhibited a very rapid (within 2 hours) reduction from pre-exercise values after eccentric exercise to a relatively stable concentration of approximately 85% of baseline. Conclusion. These results suggest that serum TC concentration may follow the time-course of reductions in force generating capacity more closely than other biochemical markers of muscle damage.

Exercise training for patients with heart failure: A systematic review of factors that improve mortality and morbidity

PURPOSE: To determine the efficacy of exercise training and its effects on outcomes in patients with heart failure. METHODS: MEDLINE, Medscape, and the Cochrane Controlled Trials Registry were searched for trials of exercise training in heart failure patients. Data relating to training protocol, exercise capacity, and outcome measures were extracted and reviewed. RESULTS: A total of 81 studies were identified: 30 randomized controlled trials, five nonrandomized controlled trials, nine randomized crossover trials, and 37 longitudinal cohort studies. Exercise training was performed in 2387 patients. The average increment in peak oxygen consumption was 17% in 57 studies that measured oxygen consumption directly, 17% in 40 studies of aerobic training, 9% in three studies that only used strength training, 15% in 13 studies of combined aerobic and strength training, and 16% in the one study on inspiratory training. There were no reports of deaths that were directly related to exercise during more than 60,000 patient-hours of exercise training. During the training and follow-up periods of the randomized controlled trials, there were 56 combined (deaths or adverse events) events in the exercise groups and 75 combined events in the control groups (odds ratio [OR] = 0.98; 95% confidence interval [Cl]: 0.61 to 1.32; P = 0.60). During this same period, 26 exercising and 41 nonexercising subjects died (OR = 0.71; 95% CT: 0.37 to 1.02; P = 0.06). CONCLUSION: Exercise training is safe and effective in patients with heart failure. The risk of adverse events may be reduced, but further studies are required to determine whether there is any mortality benefit. (C) 2004 by Excerpta Medica Inc.

The role of the complement system in ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury is a common clinical event with the potential to seriously affect, and sometimes kill, the patient. Interruption of blood supply causes ischemia, which rapidly damages metabolically active tissues. Paradoxically, restoration of blood flow to the ischemic tissues initiates a cascade of pathology that leads to additional cell or tissue injury. I/R is a potent inducer of complement activation that results in the production of a number of inflammatory mediators. The use of specific inhibitors to block complement activation has been shown to prevent local tissue injury after I/R. Clinical and experimental studies in gut, kidney, limb, and liver have shown that I/R results in local activation of the complement system and leads to the production of the complement factors C3a, C5a, and the membrane attack complex. The novel inhibitors of complement products may find wide clinical application because there are no effective drug therapies currently available to treat I/R injuries.

Magnetic resonance imaging analysis of the upper cervical spine extensor musculature in an asymptomatic cohort: an index of fat within muscle

AIM: To establish a simple method to quantify muscle/fat constituents in cervical muscles of asymptomatic women using magnetic resonance imaging (MRI), and to determine whether there is an age effect within a defined age range. MATERIALS AND METHODS: MRI of the upper cervical spine was performed for 42 asymptomatic women aged 18-45 years. The muscle and fat signal intensities on axial spin echo T1-weighted images were quantitatively classified by taking a ratio of the pixel intensity profiles of muscle against those of intermuscular fat for the rectus capitis posterior major and minor and inferior obliquus capitis muscles bilaterally. Inter- and intra-examiner agreement was scrutinized. RESULTS: The average relative values of fat within the upper cervical musculature compared with intermuscular fat indicated that there were only slight variations in indices between the three sets of muscles. There was no significant correlation between age and fat indices. There were significant differences for the relative fat within the muscle compared with intermuscular fat and body mass index for the right rectus capitis posterior major and right and left inferior obliquus capitis muscles (p = 0.032). Intraclass correlation coefficients for intraobserver agreement ranged from 0.94 to 0.98. Inter-rater agreement of the measurements ranged from 0.75 to 0.97. CONCLUSION: A quantitative measure of muscle/fat constituents has been developed, and results of this study indicate that relative fatty infiltration is not a feature of age in the upper cervical extensor muscles of women aged 18-45 years. (C) 2005 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

The effect of upper extremity support on upper extremity posture and muscle activity during keyboard use

Forearm support during keyboard use has been reported to reduce neck and shoulder muscle activity and discomfort. However, the effect of forearm support on wrist posture has not been examined. The aim of this study was to examine the effect of 3 different postures during keyboard use: forearm support, wrist support and floating. The floating posture (no support) was used as the reference condition. A wrist rest was present in all test conditions. Thirteen participants completed 20 min wordprocessing tasks in each of the test conditions. Electromyography was used to monitor neck, shoulder and forearm muscle activity. Bilateral and overhead video cameras recorded left and right wrist extension, shoulder and elbow flexion and radial and ulnar deviation. The forearm support condition resulted in significantly less ulnar deviation (

Deep dermal burn injury results in scarless wound healing in the ovine fetus

Early to mid-term fetuses heal cutaneous incisional wounds without scars; however, fetal response to burn injury has not been ascertained. We present a fetal model of thermal injury and subsequent analysis of fetal and lamb response to burn injury. A reproducible deep dermal burn injury was created in the fetus by application of water at 66 degrees C for 7 seconds, and at 82 degrees C for 10 seconds to the lamb. Macroscopically, the area of fetal scald was undetectable from day 7 post injury, while all lamb scalds were readily identified and eventually healed with scarring. Using a five-point histopathology scoring system for alteration in tissue morphology, differences were detected between control and scalded skin at all stages in lamb postburn, but no difference was detected in the fetal model after day 7. There were also large differences in content of alpha-smooth muscle actin and transforming growth factor-beta 1 between control and scalded lamb and these differences were statistically significant at day 14 (P < 0.01). This novel model of fetal and lamb response to deep dermal injury indicates that the fetus heals a deep burn injury in a scarless fashion. Further elucidation of this specific fetal process of burn injury repair may lead to improved outcome for patients with burn injury.

Differential expression of muscle damage in humans following acute fast and slow velocity eccentric exercise

We sought to determine if the velocity of an acute bout of eccentric contractions influenced the duration and severity of several common indirect markers of muscle damage. Subjects performed 36 maximal fast (FST, n=8: 3.14 rad center dot s(-1)) or slow (SLW, n=7: 0.52 rad center dot s(-1)) velocity isokinetic eccentric contractions with the elbow flexors of the non-dominant arm. Muscle soreness, limb girth, plasma creatine kinase (CK) activity, isometric torque and concentric and eccentric torque at 0.52 and 3.14 rad center dot s(-1) were assessed prior to and for several days following the eccentric bout. Peak plasma CK activity was similar in SLW (4030 +/- 1029 U center dot l(-1)) and FST (5864 +/- 2664 U center dot l(-1)) groups, (p > 0.05). Both groups experienced similar decrement in all strength variables during the 48 hr following the eccentric bout. However, recovery occurred more rapidly in the FST group during eccentric (0.52 and 3.14 rad center dot s(-1)) and concentric (3.14 rad center dot s(-1)) post-testing. The severity of muscle soreness was similar in both groups. However, the FST group experienced peak muscle soreness 48 hr later than the SLW group (24 hr vs. 72 hr). The SLW group experienced a greater increase in upper arm girth than the FST group 20 min, 24 hr and 96 hr following the eccentric exercise bout. The contraction velocity of an acute bout of eccentric exercise differentially influences the magnitude and time course of several indirect markers of muscle damage.

Resistance training for the older adult: Manipulating training variables to enhance muscle strength

Resistance training has been shown to reliably and substantially enhance muscle function in older adults and these improvements can be accompanied by improved functional performance. Training variables should be manipulated to enhance muscle strength and minimize injury risks in this population.

Physical and psychological factors maintain long-term predictive capacity post-whiplash injury

Higher initial levels of pain and disability, older age, cold hyperalgesia, impaired sympathetic vasoconstriction and moderate post-traumatic stress symptoms have been shown to be associated with poor outcome 6 months following whiplash injury. This study prospectively investigated the predictive capacity of these variables at a long-term follow-up. Sixty-five of an initial cohort of 76 acutely injured whiplash participants were followed to 2-3 years post-accident. Motor function (ROM; kinaesthetic sense; activity of the superficial neck flexors (EMG) during cranio-cervical flexion), quantitative sensory testing (pressure, thermal pain thresholds and brachial plexus provocation test), sympathetic vasoconstrictor responses and psychological distress (GHQ-28, TSK and IES) were measured. The outcome measure was Neck Disability Index (NDI) scores. Participants with ongoing moderate/severe symptoms at 2-3 years continued to manifest decreased ROM, increased EMG during cranio-cervical flexion, sensory hypersensitivity and elevated levels of psychological distress when compared to recovered participants and those with milder symptoms. The latter two groups showed only persistent deficits in cervical muscle recruitment patterns. Higher initial NDI scores (OR 1.00-1.1), older age (OR 1.00-1.13), cold hyperalgesia (OR 1.1-1.13) and post-traumatic stress symptoms (OR 1.03-1.2) remained significant predictors of poor outcome at long-term follow-up (r(2) = 0.56). The robustness of these physical and psychological factors suggests that their assessment in the acute stage following whiplash injury will be important. (c) 2006 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Alterations in dihydropyridine receptors in dystrophin-deficient cardiac muscle

The deficiency of dystrophin, a critical membrane stabilizing protein, in the mdx mouse causes an elevation in intracellular calcium in myocytes. One mechanism that could elicit increases in intracellular calcium is enhanced influx via the L-type calcium channels. This study investigated the effects of the dihydropyridines BAY K 8644 and nifedipine and alterations in dihydropyridine receptors in dystrophin-deficient mdx hearts. A lower force of contraction and a reduced potency of extracellular calcium (P < 0.05) were evident in mdx left atria. The dihydropyridine agonist BAY K 8644 and antagonist nifedipine had 2.7- and 1.9-fold lower potencies in contracting left atria (P < 0.05). This corresponded with a 2.0-fold reduction in dihydropyridine receptor affinity evident from radioligand binding studies of mdx ventricular homogenates (P < 0.05). Increased ventricular dihydropyridine receptor protein was evident from both radioligand binding studies and Western blot analysis and was accompanied by increased mRNA levels (P < 0.05). Patch-clamp studies in isolated ventricular myocytes showed no change in L-type calcium current density but revealed delayed channel inactivation (P < 0.05). This study indicates that a deficiency of dystrophin leads to changes in dihydropyridine receptors and L-type calcium channel properties that may contribute to enhanced calcium influx. Increased influx is a potential mechanism for the calcium overload observed in dystrophin-deficient cardiac muscle.

Inflammatory markers are associated with ventilatory limitation and muscle dysfunction in obstructive lung disease in well functioning elderly subjects

Background: Inflammatory markers are increased in chronic obstructive pulmonary disease ( COPD) and are hypothesised to play an important part in muscle dysfunction and exercise intolerance. Methods: The Health Aging and Body Composition ( Health ABC) study is a prospective observational cohort of well functioning individuals aged 70 - 79 years. A cross sectional analysis of the baseline data was conducted to examine the association between inflammatory markers and ventilatory limitation, muscle strength, and exercise capacity. These associations were compared in participants with and without obstructive lung disease ( OLD). Results: Of the 3075 participants enrolled in the Health ABC cohort, OLD was identified by spirometric testing in 268 participants and 2005 participants had normal spirometric results. Of the participants with OLD, 35%, 38%, and 27% participants had mild, moderate, and severe OLD, respectively. Participants with OLD had lower quadriceps strength (102.5 Nm v 108.9 Nm, p = 0.02), lower maximum inspiratory pressure (64.7 cm H2O v 74.2 cm H2O, p< 0.0001), higher systemic interleukin (IL)-6 levels (2.6 pg/ml v 2.2 pg/ml, p< 0.0001), and higher C-reactive protein (CRP) levels (3.5 mg/l v 2.5 mg/l, p< 0.0001) than those with normal spirometry. In participants with OLD and those with normal spirometry, forced expiratory volume in 1 second (FEV1) was associated with IL-6 ( adjusted regression coefficients (beta) = -5.3 (95% CI -9.1 to -1.5) and -3.1 (95% CI -4.3 to -1.9), respectively). IL-6 and TNF were also associated with quadriceps strength among participants with OLD and those with normal spirometry (beta = -6.4 (95% CI -12.8 to -0.03) and -3.4 (95% CI -5.4 to -1.3), respectively, for IL-6 and beta = -10.1 (95% CI -18.7 to -1.5) and -3.8 (95% CI -7 to -0.6), respectively, for TNF). IL-6, quadriceps strength, and maximum inspiratory pressures were independent predictors of reduced exercise capacity in both groups. Conclusions: In well functioning elderly subjects with or without OLD, IL-6 is associated with reduced FEV1, quadriceps strength, and exercise capacity.

Physical activity for people with cardiovascular disease: recommendations of the National Heart Foundation of Australia

* To provide physical activity recommendations for people with cardiovascular disease, an Expert Working Group of the National Heart Foundation of Australia in late 2004 reviewed the evidence since the US Surgeon General’s Report: physical activity and health in 1996. * The Expert Working Group recommends that: o people with established clinically stable cardiovascular disease should aim, over time, to achieve 30 minutes or more of moderate intensity physical activity on most, if not all, days of the week; o less intense and even shorter bouts of activity with more rest periods may suffice for those with advanced cardiovascular disease; and o regular low-to-moderate level resistance activity, initially under the supervision of an exercise professional, is encouraged. * Benefits from regular moderate physical activity for people with cardiovascular disease include augmented physiological functioning, lessening of cardiovascular symptoms, enhanced quality of life, improved coronary risk profile, superior muscle fitness and, for survivors of acute myocardial infarction, lower mortality. * The greatest potential for benefit is in those people who were least active before beginning regular physical activity, and this benefit may be achieved even at relatively low levels of physical activity. * Medical practitioners should routinely provide brief, appropriate advice on physical activity to people with well-compensated, clinically stable cardiovascular disease.

Rapid Atrophy of the Lumbar Multifidus Follows Experimental Disc or Nerve Root Injury.

Study Design. Experimental study of muscle changes after lumbar spinal injury. Objectives. To investigate effects of intervertebral disc and nerve root lesions on cross-sectional area, histology and chemistry of porcine lumbar multifidus. Summary of Background Data. The multifidus cross-sectional area is reduced in acute and chronic low back pain. Although chronic changes are widespread, acute changes at 1 segment are identified within days of injury. It is uncertain whether changes precede or follow injury, or what is the mechanism. Methods. The multifidus cross-sectional area was measured in 21 pigs from L1 to S1 with ultrasound before and 3 or 6 days after lesions: incision into L3 - L4 disc, medial branch transection of the L3 dorsal ramus, and a sham procedure. Samples from L3 to L5 were studied histologically and chemically. Results. The multifidus cross-sectional area was reduced at L4 ipsilateral to disc lesion but at L4 - L6 after nerve lesion. There was no change after sham or on the opposite side. Water and lactate were reduced bilaterally after disc lesion and ipsilateral to nerve lesion. Histology revealed enlargement of adipocytes and clustering of myofibers at multiple levels after disc and nerve lesions. Conclusions. These data resolve the controversy that the multifidus cross-sectional area reduces rapidly after lumbar injury. Changes after disc lesion affect 1 level with a different distribution to denervation. Such changes may be due to disuse following reflex inhibitory mechanisms.

Cardiac contributions to exercise training responses in patients with chronic heart failure: A strain imaging study

The improvement of exercise capacity due to exercise training in heart failure has been associated with peripheral adaptation, but the contribution of cardiac responses is less clear. We sought the extent to which the improvement of functional capacity in patients undergoing exercise training for heart failure was related to myocardial performance. Thirty-seven patients (35 men, age 64 +/- 11) with symptomatic heart failure and left ventricular ejection fraction