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[Acute ischemia of the leg in a drug addict].

A 39 year old male comes to the emergency room because of rapidly increasing pain in his left leg one hour after the injection of Flunitrazepam into a groin vessel. There is a history of drug abuse for more than 15 years. The left leg is cool and shows intense patchy cyanosis. The same skin discoloration is seen at the left lower abdomen and parts of the thigh. The leg is paretic but foot-pulses are detectable. Color-coded duplex-sonography of the left leg shows normal shaped arteries with regular flow. Regarding the veins there are post-thrombotic changes but no signs of actual thrombosis. The ECG shows sinus rythme. No source of emboli can be found by echocardiography. The laboratory tests reveal normal results except of anemia (Hb 9.6 g/dl, normocytic, normochromic). As an accidental intraarterial injection with a toxic/allergic insult to the vessel-walls has to be supposed the patient is treated besides of analgesics with systemic anticoagulation, high doses of cortisone and calcium channel-blockers. With this therapeutic regimen the leg and the left lower abdomen improve gradually except for some toes which remain cyanotic. During the first days the patient develops signs of moderate rhabdomyolysis with swelling of the leg and an increase of creatininase concentration in blood. After 12 days the left leg has normalised but the toes show further demarcation. They have to be amputated six weeks later. The accidental injection of drugs into the femoral artery may result in the clinical picture of acute limb ischemia without occlusion of the big vessels of the leg. This obviously occurs most often with benzodiazepines, especially when crushed tablets soluted in water are injected. Color-coded duplex sonography is able to show open vessels within minutes and prevents ineffective surgical interventions.

Adult↗

Is oscillometric ankle pressure reliable in leg vascular disease?

The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0.52 was used, the mean difference between CW Doppler and oscillometry was 1.7 mmHg [range -19 to +27, limits of agreement (2 SD) 21.1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28.8 mmHg [range -126 to +65, limits of agreement 82.8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.

Aged↗

The microbiology of infected and noninfected leg ulcers.

BACKGROUND: A clinical study was undertaken to investigate and compare specifically the aerobic and anaerobic microbiology of infected and noninfected leg ulcers. METHODS: Leg ulcers, defined as being infected on the basis of clinical signs, were swab sampled and investigated for aerobic and anaerobic microorganisms using stringent isolation and identification techniques. RESULTS: Two hundred and twenty isolates were cultured from 44 infected leg ulcers, in comparison with 110 isolates from 30 noninfected leg ulcers. Statistical analysis indicated a significantly greater mean number of anaerobic bacteria per infected ulcer (particularly Peptostreptococcus spp. and Prevotella spp.) in comparison with the noninfected ulcer group (2.5 vs. 1.3, respectively) (P < 0.05). Also, anaerobes represented 49% of the total microbial composition in infected leg ulcers compared with 36% in noninfected leg ulcers. The mean numbers of aerobes per wound in the two ulcer groups were not statistically different (P > 0.05). The study failed to demonstrate a clear correlation between commonly implicated facultative pathogens and wound infection. The isolation rate of Pseudomonas aeruginosa was generally low and, although Staphylococcus aureus was a frequent isolate in both wound types, it was more prevalent in noninfected leg ulcers. CONCLUSIONS: This study has demonstrated the complex aerobic-anaerobic microflora which exists in leg ulcers, the prevalence of anaerobes in infected wounds, and a poor correlation between the presence of specific aerobic pathogens and wound infection. In view of these findings, the role of microbial synergistic interactions in the pathogenesis of chronic wound infection may be of greater clinical importance than the isolated involvement of any specific potential pathogen.

Anti-Bacterial Agents↗

A side-by-side comparative study of 1064 nm Nd:YAG, 810 nm diode and 755 nm alexandrite lasers for treatment of 0.3-3 mm leg veins.

BACKGROUND: Laser and intense pulsed light device treatments of leg veins have generally yielded disappointing results. Use of longer wavelengths, longer pulse widths, and better cooling devices have recently sparked renewed interests in these methods. OBJECTIVE: To prospectively compare, side by side, a 3-msec cryogen spray-equipped 755 nm alexandrite, a sapphire window cooled super-long-pulse 810 nm diode, and a variable pulse width, cryogen spray-equipped 1064 nm Nd:YAG laser for the treatment of 0.3-3mm leg veins. METHODS: Thirty female volunteers, skin types I-V, age 32-67 years with comparable sets of leg veins were treated with the Nd:YAG laser and either the diode laser, alexandrite laser, or both. In most patients two to three sets of comparable sites were treated. Treatment parameters varied with each laser and according to the size of veins being treated. Patients were examined 1 week after each treatment and at 1, 2, and 3 months after the last treatment. Pre- and posttreatment 35mm photographs were taken. Improvement was judged by two experienced physicians both visually on patients and by comparison of pre- and posttreatment photographs. Results were graded as percent resolution, in five groups, 0%, 0-25%, 25-50%, 50-75%, and 75-100%. RESULTS: In the 22 patients completing the study, 36 leg vein sites were treated with the Nd:YAG laser, 18 leg vein sites were treated with the diode laser, and 12 leg vein sites were treated with the alexandrite laser. Greater than 75% improvement was observed at 88% of the Nd:YAG laser-treated sites, 29% of the diode laser-treated sites, and 33% of the alexandrite laser-treated sites. Greater than 50% improvement was observed at 94% of the Nd:YAG laser-treated sites, 33% of the diode laser-treated sites, and 58% of the alexandrite laser-treated sites. Less than 25% improvement was observed at 6% of the Nd:YAG laser-treated sites, 39% of the diode laser-treated sites, and 33% of the alexandrite laser-treated sites. Pain during treatment was variably perceived by patients, but occasionally sufficient for patients to decline further treatment. Posttreatment purpura and telangiectatic matting were a significant drawback for the alexandrite laser. Transient hemosiderin pigmentation, as seen with sclerotherapy, was common with larger vessels. CONCLUSION: The cryogen spray-equipped 1064 nm Nd:YAG laser was remarkably effective and safe for the treatment of 0.3-3 mm leg veins. The use of topical anesthesia may be needed for some patients. The super-long-pulse 810 nm diode laser gave unpredictable results. Additional refinements of fluence and pulse width could improve its performance. The 3-msec, 755 nm alexandrite laser at fluences of 60-70 J/cm2 and an 8 mm spot can be effective, but inflammatory response, purpura, and matting limit its usefulness. Longer pulse widths might decrease these problems. For leg vein treatment, the 1064 nm wavelength is very safe for type V skin, the 810 nm wavelength at super-long pulse widths of 400-1000 msec is very safe for type IV and marginal for type V skin, and the 755 nm wavelength is limited to nontanned type I-III skin.

Adult↗

Primary cutaneous large B-cell lymphoma of the leg: histogenetic analysis of a controversial clinicopathologic entity.

This study analyzes the pathologic and molecular features of 5 cases of primary cutaneous large B-cell lymphoma of the leg (PCLBCL-leg), recently included in the European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphoma. PCLBCL-leg accounts for 5% to 10% of all primary cutaneous B-cell lymphoma (PCBCL), usually affects elderly patients and carries a worse prognosis than other forms of PCBCL. It has been proposed that the malignant cells of PCLBCL-leg originate from germinal center (GC)-related cells, but their effective normal counterpart is unclear, and the rationale behind the inclusion of this lymphoma as a separate entity is based on its prognosis rather than on its proved histogenesis. All of our cases of PCLBCL-leg morphologically resembled diffuse large B-cell lymphoma (DLBCL), but to better define their histogenesis, we also analyzed various phenotypic and genotypic markers, including mutations of the Ig and of BCL-6 genes, as well as expression of the bcl-6, MUM1, and CD138/syndecan-1 proteins. Immunohistochemically, all of our cases stained for the L-26/CD20cy and CD79a antigens and expressed the bcl-2, bcl-6, and MUM-1 proteins but were negative for both the CD10/CALLA and CD138 antigens. With respect to molecular analysis, the lymphoma population of all PCLBCL-leg carried hypermutation of Ig genes, and all but 1 case also harbored mutations of the BCL-6 gene. Our results indicate that PCLBCL-leg are similar both under the morphofunctional and molecular profiles to most DLBCL of other sites. Thus, caution seems justified before definitely considering PCLBCL of the leg as a distinct entity.

Aged↗

Influence of beta-adrenoceptor blockade on leg blood flow and lactate release in man.

Nine healthy male volunteers were studied at rest and during exercise before and after acute local beta-blockade in one leg. Oxygen uptake, arterial pressure, heart rate, leg blood flow and arterial-femoral venous differences for oxygen and lactate were determined. In addition, five subjects were studied at rest during adrenaline infusion to test the blockade; in this situation the increase in leg blood flow and decrease in resistance seen in the control leg were prevented in the blocked leg. During exercise, the beta-blockade did not influence leg blood flow. At rest, lactate release was abolished from the blocked leg, and during exercise the release was reduced by 50%. These findings demonstrate that acute betareceptor blockade does not interfere with the exercise-induced vasadilation but has metabolic consequences reflected by a reduction in the release of lactate from the leg.

Adrenergic beta-Antagonists↗

Evolutionary history and adaptive significance of respiratory structures on the legs of intertidal porcelain crabs, genus Petrolisthes.

Semiterrestrial and terrestrial crabs have evolved multiple strategies for aerial respiration. An uncommon strategy for aerial respiration is seen in porcelain crabs, genus Petrolisthes, where decalcified areas on the meral segments of the walking legs are used as respiratory structures. Here, the evolutionary history and adaptive significance of these structures in porcelain crabs is examined. Interspecific variation in leg membrane size is from 0% to 60% of the surface area of the meral segment. Leg membrane relative size is positively correlated with body size across species but not within one species, Petrolisthes cinctipes. Phylogenetic analyses suggest that leg membranes are ancestral to one of two eastern Pacific Petrolisthes clades. Comparative analyses using phylogenetic independent contrasts indicate a relationship between leg membrane relative size and body size that is phylogenetically independent. In large-bodied intertidal species, whole-animal lactate accumulation during aerial incubation is 200%-300% higher when the leg membranes are obscured, indicating that the leg membranes are functional respiratory structures in these species. Thus, it is possible that leg membranes have facilitated the evolution of larger body sizes by providing additional respiratory surfaces to accommodate the associated higher metabolic demands.

Animals↗

Bilateral photoplethysmography studies of the leg arterial stenosis.

A newly developed portable multi-channel photoplethysmography (PPG) device has been used for comparative studies of 20 healthy control subjects and 45 patients with diagnosed arterial stenosis in a leg. The peripheral blood pulsations were detected simultaneously at four body sites-the same fingers and toes of both arms and legs. The PPG pulses recorded at the periphery of the stenotic leg, if compared with those of the healthy leg, were much weaker, with delayed arrival as a consequence of increased pulse wave transit time (PWTT) due to higher vascular resistance. The specific PWTT delays for the occluded legs were in the range of 20-80 ms, while in the case of healthy subjects the leg PPG signals arrived without delays or with smaller time-shifts not exceeding 14 ms. The reference bilateral PPG signals detected at the fingertips did not show any notable PWTT delays in both groups. Parallel measurements of local blood pressures by means of the oscillometry method with subsequent calculation of the ankle-brachial index were performed. Convincing correlation between the bilateral differences in the local blood pressure (a routine tool for diagnostics of leg stenosis) and in the corresponding PWTT delay (Pearson's coefficient r = 0.93), as well as between the PWTT delay and the ankle-brachial index (r = -0.96) has been established. From the point of view of PWTT delay, the average value of leg stenosis diagnostic threshold was established to be in the range of 23 +/- 9 ms, with full reliability above 32 ms. The obtained data may find further applications in alternative methodologies for detection and/or assessment of arterial occlusions in human extremities.

Adult↗

Leg weakness is a complication of ilio-inguinal nerve block in children.

BACKGROUND: Ilio-inguinal nerve block is commonly used in children to provide analgesia after surgery in the groin. Several case reports and clinical studies have described leg weakness after this technique and suggest that it may caused by inadvertent femoral nerve block. No prospective studies describing the incidence of this complication have been published. METHODS: We carried out a prospective, observational study to find out how many children had leg weakness after ilio-inguinal nerve block. We studied 200 children having day-case surgery in the groin under a general anaesthetic with an ilio-inguinal nerve block. All children performed a simple leg-raising test with each leg before induction of general anaesthesia with a standardized ilio-inguinal nerve block on the side of surgery. When the child was awake and comfortable after surgery, they repeated the leg-raising test. RESULTS: Sixteen of 182 children (8.8%) had leg weakness after surgery on the side of the nerve block only, as detected by a leg-raising test. CONCLUSIONS: Leg weakness consistent with a femoral nerve block occurs after ilio-inguinal nerve block in approximately one in nine children.

Ambulatory Surgical Procedures↗

Contribution of pelvic and lower limb motion to increases in the angle of passive straight leg raising.

We undertook this study to determine the relative contributions of pelvic and lower limb motion to increases in the angle of passive straight leg raising in the sagittal plane. Seventeen healthy subjects underwent passive straight leg raising of their relaxed left lower limb while their right lower limb was held firmly against the table. Each subject's pelvis and left lower limb were marked so that cinematography could document motion of the pelvis and left lower limb during passive straight leg raising. Film analysis revealed that pelvic rotation began within 9 degrees of the beginning of passive straight leg raising and that the relative contribution of pelvic rotation to the angle of passive straight leg raising in relation to the horizontal plane increased in conjunction with the angle of straight leg raising. Clinicians using the passive straight-leg-raising test should be aware of the contribution of pelvic rotation to the angle of straight leg raising when interpreting test results.

Adult↗

Passive leg raising does not produce a significant or sustained autotransfusion effect.

Passive leg raising is widely used to treat hypotension associated with hypovolemia. Presumably gravity causes a central translocation of leg venous blood and an increase in filling pressure, cardiac output, and arterial pressure. Ten healthy volunteers, 25 to 35 years old, had measurements of heart rate, blood pressure, and cardiac output in the supine position after 20 sec and 7 min of 60 degrees passive leg elevation. The protocol was performed 3 and 45 min after the subjects changed from an ambulatory upright to a supine position. Stroke volume and cardiac output increased transiently (8-10%) when the legs were raised after 3 min rest in the supine position. By 7 min of leg elevation, these beneficial effects disappeared. After 45 min supine, leg raising had no effect on stroke volume or cardiac output but increased blood pressure (4 mm Hg) by increasing peripheral resistance (15%). Thus, leg raising, like application of the MAST trousers, fails to produce any sustained increase in cardiac output or stroke volume. Small venous leg volumes and time-dependent changes in the distribution of venous volume and compliance may explain the absence of any sustained 'autotransfusion' effect.

Adult↗

Single-leg Wingate Test in children: reliability and optimal braking force.

PURPOSE: Single-leg cycle ergometry employing the protocol of the Wingate Test (WAnT) has been used to assess unilateral muscle power and leg-dominance. The objectives of this study were to determine the reliability of the single-leg WAnT (SLWAnT) and to establish optimal braking force for the SLWAnT. METHODS: Twenty female and 19 male subjects (prepubertals: 6.0-9.9 yr, 7 female and 6 male; midpubertals: 11.0-14.9 yr, 7 female and 7 male; and postpubertals: 17.0-20.9 yr, 6 female and 6 male) came to the laboratory on three occasions. On each visit, they first performed two SLWAnT after a standardized warm-up, one with each leg. Braking force for these tests was kept constant throughout all visits. On each of the following visits, subjects performed four additional SLWAnT, two with each leg, with braking force varying from test to test to determine the braking force associated with the highest performance over 30 s. RESULTS: Although a significant increase in performance was observed from visit to visit in some groups, intraclass correlation coefficients (which included trial-to-trial differences) of peak power and total work generated during the first two SLWAnT of each visit ranged from 0.89 to 0.98. Optimal braking force (J x rev(-1)) could be estimated from 0.4052 x body mass(1.4662) for all subjects irrespective of gender or maturity. The standard error of estimate was lowest in the prepubertals and highest in postpubertals (8.3-31.4 J x rev(-1)). CONCLUSIONS: SLWAnT is a highly reliable method to measure single-leg power. The above equation provides good estimates of optimal braking force. The SLWAnT can, therefore, be used to monitor changes in single-leg power and to assess leg-dominance.

Adolescent↗

Lean body mass and leg power best predict bone mineral density in adolescent girls.

PURPOSE: We evaluated anthropometric and performance measures that best predict bone mineral density (BMD) and bone mineral content (BMC) in 54 adolescent girls (14.6 +/- 0.5 yr; 22.7 +/- 14.0 months past menarche). METHODS: Whole body, femoral neck, greater trochanter, lumbar spine (L2-L4), and mid-femoral shaft BMD and BMC, and whole body bone-free lean mass and fat mass were assessed using DXA (Hologic QDR 1000/W). Knee extensor strength and leg power were assessed by isokinetic dynamometry and the Wingate Anaerobic Power Test, respectively. RESULTS: Whole body lean mass was correlated with BMD at all bone sites (r = 0.45-0.77; P < 0.001) and was more highly correlated with bone at all sites than was body weight. Leg power was also associated with BMD at all sites (r = 0.41-0.67; P < 0.001), whereas leg strength correlated significantly with all sites (r = 0.41-0.53; P < 0.001) except the lumbar spine. Stepwise regression analyses revealed that 59% of the variance in whole body BMD was predicted by lean mass alone. No other variables, including fat mass, height, months past menarche, leg power, or leg strength, contributed additionally to the regression model. Similarly, lean mass was the only predictor of lumbar spine and femoral shaft BMD (R2 = 0.25, R2 = 0.37, respectively), while femoral neck and trochanteric BMD were best predicted by leg power (R2 = 0.38, R2 = 0.36, respectively). Similar but stronger models emerged using BMC as the outcome, with lean mass and leg power explaining the most variance in BMC values. CONCLUSION: In this group of adolescent girls, lean body mass and leg power best predicted BMC and BMD of the whole body, lumbar spine, femoral shaft, and hip, which may suggest an important role for muscle mass development during growth to maximize peak bone density.

Absorptiometry, Photon↗

Plasma catecholamine and blood lactate responses to incremental arm and leg exercise.

PURPOSE AND METHODS: The present study was conducted to examine the pattern of plasma catecholamine and blood lactate responses to incremental arm and leg exercise. Seven untrained male subjects performed two incremental exercise tests on separate days in random order. One test consisted of 1-arm cranking (5W x 2 min(-1)), whereas the other exercise test was 2-leg cycling (20-25W x 2 min(-1)). Blood samples were obtained from the nonexercising arm during 1-arm cranking and from the same arm and vein during 2-leg cycling. Thresholds for blood lactate (T(La)), epinephrine (T(Epi)) and norepinephrine (T(NE)) were determined for each subject under both exercise conditions and defined as breakpoints when plotted as a function of power output. RESULTS: When the two modes of exercise were compared, T(La), T(Epi), and T(NE) were all significantly lower for 1-arm cranking than for 2-leg cycling (P < 0.01). During 1-arm cranking, T(La) (0.96 +/- 0.10 L x min(-1)), T(Epi) (1.02 +/- 0.07 L x min(-1)), and T(NE) (1.07 +/- 0.09 L x min(-1)) occurred simultaneously. During 2-leg cycling, T(La) (1.77 +/- 0.20 L x min(-1)), T(Epi) (1.74 +/- 0.17 L x min(-1)), and T(NE) (1.98 +/- 0.17 L x min(-1)) occurred at similar levels of VO2 and were not significantly different. The correlation observed between the VO2 measured at the T(La) and T(Epi) was 0.917 for arm and 0.929 for leg exercise (P < 0.001). The epinephrine concentration ([Epi]) obtained at the T(La) was not significantly different for arm (0.144 ng x mL(-1)) and leg (0.152 ng x mL(-1)) exercise. CONCLUSIONS: The breakpoint in plasma [Epi] shifted in an identical manner and occurred simultaneously with that of T(La) regardless of the mode of exercise (arm or leg). The Epi concentrations observed at the T(La) agree with those previously reported to produce a rise in blood lactate during Epi infusion at rest. These results support the hypothesis that a rise in plasma [Epi] may contribute to the breakpoint in blood lactate that occurs during incremental exercise.

Adult↗

Arm and leg power output in swimmers during simulated swimming.

PURPOSE: Previously, it has not been possible to compare power output of the arms and legs during simulated swimming using dry-land ergometry. The purpose of this study was to determine arm-pulling and leg-kicking power using isokinetic dry-land ergometry. METHODS: Twenty-two highly trained male swimmers of mean (+/- SD) age, 23 +/- 3.6 yr; body mass, 78 +/- 5.9 kg; and stature, 1.79 +/- 0.04 m were recruited to the study. First, subjects performed 10 s of all-out exercise at each of five resistance settings, with 1 h rest in between, to determine the best maximal pull velocity (MPVopt). Second, they performed an all-out 30-s test at MPVopt, which was repeated the following day. These repeated 30-s tests were performed separately using simulated front-crawl arm-pulling and leg-kicking, on a computer-interfaced swim bench and purpose-built leg-kicking ergometer. Peak and mean power output (PPO; MPO) were determined from regression analysis of the power vs time relationship. RESULTS: The mean (+/- SEM) PPO for arms and legs were 304 +/- 22 W versus 435 +/- 36 W. For MPO, the means were 225 +/- 31 W vs 312 +/- 26 W, respectively. These values were attained at mean MPVopt of 2.5 +/- 0.2 m x s(-l) for arms and 2.3 +/- 0.4 m x s(-1) for legs. The variation in PPO from repeated testing was 7.3% for arms and 8.3% for legs. CONCLUSIONS: These results show that the legs can sustain greater power output than the arms during simulated swimming. Also, the intra-subject variation in measurement of power output is small using these dry-land ergometers. These methods of assessment might be useful in explaining swimming performance and in monitoring changes that take place during training.

Adolescent↗

Postexercise protein intake enhances whole-body and leg protein accretion in humans.

PURPOSE: Exercise increases the use of amino acids for glucose production and stimulates the oxidation of amino acids and other substrates to provide ATP for muscular contraction, and thus the availability of amino acids and energy for postexercise muscle protein synthesis may be limiting. The purpose of this study was to determine the potential of postexercise nutrient intake to enhance the recovery of whole-body and skeletal muscle protein homeostasis in humans. METHODS: Primed-continuous infusions of L-[1-13C]leucine and L-[ring-2H5]phenylalanine were initiated in the antecubital vein and blood was sampled from a femoral vein and a heated (arterialized) hand vein. Each study consisted of a 30-min basal, a 60-min exercise (bicycle at 60% VO2max), and a 180-min recovery period. Five men and five women were studied three times with an oral supplement administered immediately following exercise in random order: NO = 0, 0, 0; SUPP = 0, 8, 3; or SUPP+PRO = 10, 8, 3 g of protein, carbohydrate, and lipid, respectively. RESULTS: Compared to NO, SUPP did not alter leg or whole-body protein homeostasis during the recovery period. In contrast, SUPP+PRO increased plasma essential amino acids 33%, leg fractional extraction of phenylalanine 4-fold, leg uptake of glucose 3.5-fold, and leg and whole-body protein synthesis 6-fold and 15%, respectively. Whereas postexercise intake of either NO or SUPP resulted in a net leg release of essential amino acids and net loss of whole-body and leg protein, SUPP+PRO resulted in a net leg uptake of essential amino acids and net whole-body and leg protein gain. CONCLUSIONS: These findings suggest that the availability of amino acids is more important than the availability of energy for postexercise repair and synthesis of muscle proteins.

Adult↗

An electromyographic comparison of abdominal muscle synergies during curl and double straight leg lowering exercises with control of the pelvic position.

STUDY DESIGN: This prospective study evaluated the abdominal muscle activity during the Isometric bent knee curl and double straight leg lowering exercise. OBJECTIVES: To compare the magnitude of the electromyographic activity across the curl and double straight leg lowering exercise and determine if the muscle synergies were specific to a given exercise. SUMMARY OF BACKGROUND DATA: Abdominal muscle strengthening exercises are frequently recommended in the prevention and rehabilitation of individuals with low back pain. Previous studies comparing the curl exercise with the double straight leg lowering exercise did not support the notion that the double straight leg lowering exercise is more demanding on the abdominal muscles. No previous study examined these two exercises while maintaining a constant pelvic position. METHODS: Fifteen male subjects had the electromyographic activity of the rectus abdominis, the external oblique, and the internal oblique abdominal muscles evaluated during the curl and double straight leg lowering exercise. The same position of the posterior pelvic tilt was maintained between each exercise using feedback from an electrogoniometer attached to the pelvis. RESULTS: The double straight leg lowering exercise resulted in significantly greater activation of the abdominal muscles compared with the curl. Two abdominal muscle synergies emerged during the double straight leg lowering exercise: synergy I exhibited high rectus abdominis, high external oblique, and low internal oblique muscle activity, whereas synergy II exhibited low rectus abdominis, high external oblique, and high internal oblique. CONCLUSIONS: The results support the use of the double straight leg lowering with the posterior pelvic tilt for achieving greater abdominal muscle coactivation in an exercise program.

Abdominal Muscles↗

Intrathecal movement and tension of the lumbosacral roots induced by straight-leg raising.

OBJECTIVE: To obtain quantitative biomechanical data on the effects of different angles of straight-leg raising on intrathecal movements and tensions in the lumbosacral nerve roots in human cadavers. DESIGN: Eight embalmed human cadavers with no gross spinal pathology and no limitations in hip motion were used. We performed reverse straight-leg raising by hanging the left leg down from the table with the knee extended while measuring the movement and tension of nerve roots L2, L3, L4, L5, and S1 in 10-degree intervals for straight-leg raising from 0 to 70 degrees. RESULTS: The mean intrathecal movements at 70 degrees were 0.55 mm, 0.54 mm, 0.96 mm, 1.54 mm, and 2.31 mm for roots L2, L3, L4, L5, and S1, respectively. The movements were statistically significant at >50 degrees for root L5 and at >40 degrees for root S1 (P < 0.05). The tension in the nerve roots with increasing angle of straight-leg raising increased from roots L2 to S1. The mean tensions at 70 degrees of straight-leg raising were 141.25 g, 168.75 g, 228.75 g, 280.00 g, and 493.75 g for roots L2, L3, L4, L5, and S1, respectively. The difference in tension was significant at >70 degrees for roots L2, L3, and L4 roots, at >40 degrees for root L5 root, and at >10 degrees for root S1 (P < 0.05). CONCLUSIONS: The intrathecal movement and tension of the lumbosacral roots induced by straight-leg raising were <2.5 mm and <500 g, respectively. The movement and tension induced by straight-leg raising tended to be greater in more distal segmental roots.

Biomechanical Phenomena↗