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PubMed1986

Interaction between the leg and surrounding thorax in the beetle.

Interactions between the insect leg and surrounding thoracic epidermis were studied in the beetle, Tenebrio, by grafting the entire larval prothoracic leg into the metathoracic leg site in various orientations. Control grafts simply heal, but A/P reversed grafts lead to regeneration of supernumerary legs of host orientation in A and P positions. M/L reversed grafts also give supernumeraries, again with host orientation but in M (or MP) and L (or LA) positions. The differences in structure between adult prothoracic and metathoracic legs allow the origin of these supernumeraries to be analysed at coxa and tarsus level. The A/P supernumeraries are consistent and complementary in structure, of host origin on the host side and graft origin on the graft side, and with the borders in apparently constant midmedial and midlateral positions. The M/L supernumeraries, however, are variable and often non-complementary in structure. The results of the A/P and M/L reversals are similar to those found at a more distal level in Tenebrio legs and the legs of several hemimetabolous insects, suggesting that the arrangement of positional values and A and P compartments extends from the epidermis of the leg onto the surrounding thorax. The results of a 180 degrees rotation of the entire leg, however, differ from those found at a more distal level in that the grafted leg rarely derotated and two (or occasionally one or three) supernumeraries are formed in a wide variety of positions, some with constant and others with variable orientation. These results are not readily explained by current models of insect leg formation and regeneration.

Animals↗
PubMed1995

Strategy that includes serial noninvasive leg tests for diagnosis of thromboembolic disease in patients with suspected acute pulmonary embolism based on data from PIOPED. Prospective Investigation of Pulmonary Embolism Diagnosis.

OBJECTIVE: To estimate the percentage of patients with suspected acute pulmonary embolism in whom a noninvasive diagnosis or exclusion of thromboembolic disease might be safely made on the basis of ventilation-perfusion (VQ) lung scans, single noninvasive tests of the lower extremities, and, in patients with adequate cardiorespiratory reserve, serial noninvasive tests of the lower extremities. METHODS: Calculations were made among 662 patients who participated in the collaborative study Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) and who had blood gas values measured while breathing room air and who underwent pulmonary angiography. The diagnostic strategy recommends treatment in all patients with a high-probability VQ scan and no treatment in patients with nearly normal VQ scans. In patients with nondiagnostic VQ scans (intermediate- or low-probability scans), a single noninvasive leg test is recommended. It was assumed that 50% of patients with pulmonary embolism would show deep venous thrombosis with a single noninvasive leg test. If results are abnormal, treatment is indicated. If normal, serial noninvasive leg tests are recommended. Treatment can be withheld if results of serial tests are normal. In patients with poor cardiorespiratory reserve, pulmonary angiography is indicated. RESULTS: A single noninvasive leg test in patients with nondiagnostic VQ scans would show deep venous thrombosis and, therefore, eliminate the need for pulmonary angiography in 53 (11%) of 468 patients (95% confidence interval [CI], 9% to 15%) who otherwise would require angiography. Serial noninvasive leg tests in patients with adequate cardiorespiratory reserve who had a normal result of a single leg test would either show deep venous thrombosis or exclude it in 222 (47%) of 468 patients (95% CI, 43% to 52%). The need for pulmonary angiography, therefore, would be reduced from 468 (71%) of 662 (95% CI, 67% to 74%) if no noninvasive leg tests were performed to 415 (63%) of 662 (95% CI, 59% to 66%) if only a single noninvasive leg test were performed, and further reduced to 193 (29%) of 662 (95% CI, 26% to 33%) if serial noninvasive leg tests were used where appropriate. CONCLUSION: A noninvasive strategy that includes VQ scans, single noninvasive leg tests, and serial noninvasive leg tests would permit a diagnosis of thromboembolic disease or a safe exclusion of thromboembolic disease in 71% of patients with suspected acute pulmonary embolism.

Acute Disease↗
PubMed2000

Epidemiology of restless legs symptoms in adults.

BACKGROUND: Restless legs syndrome (RLS) is a disorder characterized by sleep-disrupting unpleasant leg sensations, often accompanied by daytime behavioral problems. Treatment for this condition is available, but it is suspected that most instances of RLS remain undiagnosed. The goal of this investigation was to assess the prevalence and health status correlates of restless legs symptoms (hereinafter referred to as restless legs) in the general population. METHODS: A question reflecting the clinical features of RLS was added to the 1996 Kentucky Behavioral Risk Factor Surveillance Survey. Data on the frequency of experiencing restless legs, self-rated general and mental health status, demographics, and behavioral risk factors were collected by telephone interview from 1803 men and women, 18 years and older. RESULTS: Experiencing restless legs 5 or more nights per month was reported by 3% of participants aged 18 to 29 years, 10% of those aged 30 to 79 years, and 19% of those 80 years and older. The age-adjusted prevalence for Kentucky adults is 10.0%; prevalence did not vary significantly by sex. The adjusted odds ratios (95% confidence intervals) for restless legs and diminished general health and poor mental health status were 2.4 (1.4-4.0) and 3.1 (2.0-4.6), respectively. Restless legs were significantly associated with increased age and body mass index, lower income, smoking, lack of exercise, low alcohol consumption, and diabetes. CONCLUSIONS: The prevalence of restless legs in the general adult population is high. Restless legs may be associated with decreased well-being, emphasizing the need for further research and greater medical recognition of this condition.

Adolescent↗
PubMed2002

Effects of immobility on sensory and motor symptoms of restless legs syndrome.

Restless legs syndrome (RLS) is defined by an irresistible need to move associated with leg paresthesia. Two additional features are essential for diagnosis: (1) worsening of symptoms at rest with temporary relief by activity, and (2) worsening of symptoms during the evening and/or during the night. The suggested immobilization test (SIT) has been developed to evaluate the presence of these criteria. This test quantifies leg movements and leg discomfort during a 1-hour period of immobility prior to bedtime. We used the SIT to evaluate the effects of immobility on leg discomfort and leg movements experienced by 19 patients with RLS and 19 control subjects. Results show that immobility significantly worsens both leg discomfort and periodic leg movements (PLM) in patients with RLS but not in controls. Patients with RLS showed a higher leg discomfort score (32.6 +/- 15.1 mm vs. 5.7 +/- 7.9 mm; P < 0.00001), a greater maximum leg discomfort value (63.4 +/- 27.4 mm vs. 13.7 +/- 23.0 mm; P < 0.00001) and a greater PLM index (88.4 +/- 62.6 vs. 10.4 +/- 20.6; P < 0.00004) than control subjects. These results further validate the use of the SIT as a diagnostic and research tool for RLS and confirm the contention of the International RLS study group that RLS symptoms worsen at rest.

Adult↗
PubMed1985

The effects of mild one-legged isometric or dynamic training.

Four men isometrically trained their stronger leg for 19 weeks (attempted knee extension against a restraining strap incrementally increasing to 30 brief maximal contractions X 6 wk-1). Five others similarly trained dynamically (repeated knee extension against a 63 N resistance force, incrementally increasing to 300 extensions X 6 wk-1). Before, at regular intervals during training and after de-training (between 7-11 weeks) measurements were made using trained and control legs of: Maximum Voluntary Isometric Contraction (M.V.C.), Endurance at 60% M.V.C., Knee Extension Performance Test (K.E.P.T.) and One-legged Work Test. Isometric training produced a 30% (p less than 0.01) increase in M.V.C. with a 15% (p less than 0.05) increase in the control leg. These changes persisted with some deterioration after the de-training period. Endurance at 60% M.V.C. remained unchanged, even though M.V.C. was increasing in both trained and control legs. There was some evidence that isometric training improved the cardio-vascular response to one-legged exercise. Dynamic training did not result in changes in M.V.C., Endurance at 60% M.V.C. or the One-legged work Test, but K.E.P.T. (time taken for 50 knee extensions at a comfortable pace against 63 N resistance) improved by 33% (p less than 0.01) and 28% (p less than 0.01) in the trained and control legs respectively. Isometric training resulted in similar improvements in performance of K.E.P.T. (28%, p less than 0.05, trained leg; 18%, p less than 0.05 control leg). For similar time spent in training, isometric work appeared more effective than dynamic work in improving the parameters of muscle function, these improvements appeared to be both centrally (C.N.S.) and locally mediated.

Adult↗
PubMed1990

Is the gender difference in peak VO2 greater for arm than leg exercise?

Based on observations that the difference between men and women in estimates of arm musculature is greater than the difference in leg musculature, it was hypothesized that the gender difference in peak oxygen uptake (VO2; l.min-1) would be greater for arm exercise than leg exercise. To test this hypothesis, 19 (10 men, 9 women) highly trained swimmers (HT) and 20 (10 men, 10 women) untrained students (UT) were tested for peak VO2 on cycle and arm-crank ergometers. Arm and leg fat-free volumes (FFV) were measured to provide an estimate of muscle distribution. No gender difference was observed in either the arm-to-leg peak VO2 ratio (0.699 for the men vs 0.696 for the women) or in the arm-to-leg FFV ratio (0.410 for the men vs 0.402 for the women). Although the proportion of musculature in the arms as assessed by the FFV appeared to be the same in men and women, the similarity in muscle distribution was probably not responsible for the identical average arm-to-leg peak VO2 ratios. The variance in the muscle distribution accounted for only 2-4% of the variance in the arm-to-leg peak VO2 differences within individuals. We conclude that factors other than arm and leg muscle dimensions account for the variability in the arm-to-leg peak VO2 ratio and that the gender difference in peak VO2 is the same for arm and leg exercise.

Adult↗
PubMed1998

Postural reorganization of weight-shifting in below-knee amputees during leg raising.

The position of the center of gravity (CG) is a reference value that is controlled by the nervous system during the performance of movements. In order to maintain equilibrium, leg movement is preceded by a shift of the CG towards the supporting side. This CG shift is initiated by an early displacement of the center of pressure (CP) towards the moving leg. This characteristic CP thrust partly results from the activity of a distal muscle in the leg to be moved: the gastrocnemius medialis (GM). The aim of this study was to determine how this weight-shifting is initiated when the distal muscles are missing, as in amputees, and to identify any change in the central command. Experiments were performed on ten subjects: five below-knee amputees with no pathology and five control subjects. While standing, the subjects were instructed to raise one leg laterally as fast as possible to an angle of 45 degrees and to maintain the final position. The same weight-shifting strategy was used by both groups, whereas local adaptations associated with the behavior occurred. When the GM is lacking, an early tensor-fasciae-latae (TFL) burst is observed just prior to and associated with the onset of the lateral CP change. This moving-leg abductor may be responsible for initiating the thrust at a proximal level when that leg is still on the ground. In addition, upon analyzing the lateral displacement of the CP, two modes of CP shift were detected. The first CP-shift mode has been previously described and the second mode (which we term here the pre-pushing mode) was used by both amputees and controls. The prepushing mode consisted of two thrusts: an early thrust onto the ground was exerted by the leg about to become the supporting leg followed by the previously described thrust exerted by the leg about to be raised. The early thrust, which could be exerted by either the sound or prosthetic leg, may have increased the efficiency of the second, classical thrust by initiating a swing.

Adult↗
PubMed2000

Is lower leg proprioception essential for triggering human automatic postural responses?

It is unknown to what extent automatic postural responses are triggered by lower leg proprioception. This issue was addressed by studying postural control in five carefully selected patients with subtle diabetic polyneuropathy (restricted to the lower legs) and 15 healthy subjects. All patients had bilaterally absent Achilles tendon reflexes and weak or absent patella tendon reflexes, but muscle strength was fully preserved. Subjects were tested while standing on a supporting, movable force-plate. The contribution of lower leg proprioception to automatic postural responses was investigated by randomly exposing the subjects to either a 4 degrees 'toe-up' rotational perturbation ('normal ankle input'), a simultaneous 4-cm rearward translation and 4 degrees toe-up rotation ('enhanced ankle input'), or a simultaneous 4-cm rearward translation and 4 degrees 'toe-down' rotation ('nulled ankle input'). We recorded surface EMG (stretch reflexes and balance-correcting responses) from leg and trunk muscles, ankle torque and angular velocities of the upper and lower legs and trunk. We argued that automatic postural responses that have abnormally small amplitudes in patients and are modulated in controls with the velocity of different types of ankle rotations must receive a major input from lower leg proprioception. Conversely, automatic postural responses that are weakly modified in amplitude or onset by different ankle perturbations and are present despite nulled ankle inputs and, finally, are unaffected in patients with distal polyneuropathy must be triggered or modulated by inputs other than from lower leg proprioception. Normal postural synergies and strategies were maintained in patients, although within a given synergy the timing and amplitude of some automatic postural responses were abnormal. A few automatic postural responses appeared to be triggered or modulated by lower leg proprioception. Thus, early stretch reflexes in soleus and medial gastrocnemius were severely diminished in patients, while in controls these stretch reflexes were modulated by different ankle perturbations. Furthermore, balance-correcting responses in tibialis anterior were diminished and delayed in patients, while in controls these balance-correcting responses were modulated by different ankle perturbations. Other automatic postural responses were apparently not triggered or modulated by lower leg proprioception, but likely received a major input from more proximal sensory systems. Thus, in both groups prominent balance-correcting responses were present in several muscles (soleus, gastrocnemius, quadriceps, paraspinals and trapezius) during the 'nulled ankle input' condition, where ankle position was stabilised over the first 250 ms. During the 'enhanced ankle input' condition, where prominent ankle dorsiflexion occurred during the first 200 ms, amplitudes of balance-correcting responses were only marginally weaker in patients than in controls. We analysed body segment displacements to unveil the potential nature of proximal triggers for automatic postural responses. As opposed to the 'inverted pendulum' concept of postural control, early movement occurred in the knees, hips and trunk well before the onset of automatic postural responses. For example, during the 'nulled ankle input' condition, the lower leg moved forward with early knee flexion, followed by knee extension. The trunk extended backwards at 80 ms, which was followed by forward flexion. The absent stretch reflex and weaker balance-correcting responses in patients produced changed trunk velocity profiles (mainly a reduced initial backward motion of the trunk), but lower-body segment movements showed no consistent differences between the two groups. Considering these body segment displacements, any automatic postural response with an onset within the first 200 ms could well be triggered by receptors located at the knee, hip or trunk. (ABSTRACT TRUNCATED)

Achilles Tendon↗
PubMed2000

The effects of limb elevation and increased intramuscular pressure on nerve and muscle function in the human leg.

In this study we investigated the effects of increased intramuscular pressure (IMP) on nerve and muscle function in the leg and foot. In study A, muscle pressure was increased by inducing venous stasis in both legs, placed in plaster casts, of eight healthy subjects having a mean age of 29 years. The results from elevated and non-elevated limbs were compared. In study B, two different models for increasing IMP were studied in nine healthy subjects having a mean age of 32 years. The results of increased IMP and decreased blood perfusion pressure on local (= leg) and distal (= foot) function of muscle and nerve induced by venous stasis of a leg in a plaster cast and by external compression of the contralateral leg were compared. Contraction pressure of the tibialis anterior muscle in the leg was recorded. A biphasic compound muscle action potential was measured from the extensor hallucis brevis and the extensor digitorum muscles as an indication of foot muscle function. Muscle contraction pressure was 87 (SD 38) mm Hg in the vein-obstructed leg and 133 (SD 42) mm Hg in the externally compressed leg (P<0.05). In both studies the skin sensibility of the feet was significantly lower in the vein-obstructed elevated leg after 30 min (P<0.05). Vein stasis in an elevated human leg in a plaster cast defines a model for simulating imminent acute compartment syndrome with reversible neuromuscular dysfunction.

Action Potentials↗
PubMed1996

Leg stiffness and stride frequency in human running.

When humans and other mammals run, the body's complex system of muscle, tendon and ligament springs behaves like a single linear spring ('leg spring'). A simple spring-mass model, consisting of a single linear leg spring and a mass equivalent to the animal's mass, has been shown to describe the mechanics of running remarkably well. Force platform measurements from running animals, including humans, have shown that the stiffness of the leg spring remains nearly the same at all speeds and that the spring-mass system is adjusted for higher speeds by increasing the angle swept by the leg spring. The goal of the present study is to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when humans alter their stride frequency at a given running speed. Human subjects ran on treadmill-mounted force platform at 2.5ms-1 while using a range of stride frequencies from 26% below to 36% above the preferred stride frequency. Force platform measurements revealed that the stiffness of the leg spring increased by 2.3-fold from 7.0 to 16.3 kNm-1 between the lowest and highest stride frequencies. The angle swept by the leg spring decreased at higher stride frequencies, partially offsetting the effect of the increased leg spring stiffness on the mechanical behavior of the spring-mass system. We conclude that the most important adjustment to the body's spring system to accommodate higher stride frequencies is that leg spring becomes stiffer.

Adaptation, Physiological↗
PubMedDate not supplied

Interexaminer reliability of activator methods' relative leg-length evaluation in the prone extended position.

OBJECTIVE: To investigate the interexaminer reliability of the prone extended relative leg-length check as described by Activator Methods, Inc. SUBJECTS: Thirty-four subjects were selected from a pool of 52 consecutive patients visiting a private chiropractic office. METHODS: Exclusion criteria included congenital or acquired conditions known to affect lower extremity length and inability to lie prone for a 10-minute period. Two experienced chiropractors who specialize in Activator Methods and are "advanced-proficiency rated" by Activator Methods, Inc. assessed each patient in random order for leg length inequality. Findings were recorded as left short leg, equal leg length, or right short leg. RESULTS: The data for 34 subjects were organized in a 3 x 3 contingency table. Total agreement was 85%. A simple, unweighted kappa value yielded kappa = 0.66. A disproportionately greater number of right short leg findings than left short leg findings were observed by both examiners. In only 2 instances were equal leg lengths observed, and both were detected by the same examiner. Because examiners found only 2 of 34 subjects with equal leg lengths, several secondary analyses involving data reductions were conducted. The resulting kappa values were similar to the 3 x 3 analysis. CONCLUSION: There was good reproducibility between 2 examiners by using the Activator Method to detect leg length inequality in the prone extended position. This study does not address the validity or clinical significance of the measurement method. Future studies should include larger numbers, a wider variety of subjects, and a diversity of examiners.

Adult↗
PubMed2003

Leg ulceration as a long-term complication of deep vein thrombosis.

OBJECTIVE: To evaluate the role of deep vein thrombosis as a cause of leg ulcers. PATIENTS AND METHODS: A population-based, case-control study was conducted in Central and North Auckland, New Zealand. Cases comprised 241 people aged 40 to 99 years and on the electoral roll, with current leg ulcers (all types). Cases were identified by means of notification from health professionals and by self-referral. Controls were 224 people in the same age group, without leg ulcers, who were selected from the electoral roll by using a stratified random sampling process. MAIN OUTCOME MEASURES: The occurrence of leg ulceration as a consequence of exposure to deep vein thrombosis or being at high risk of deep vein thrombosis (that is, people with a family history of deep vein thrombosis, and/or a history of leg fracture and/or hip, leg, or foot surgery). RESULTS: After adjustment for age, sex, and other potential confounding factors, people who had a diagnosed thromboembolism were at almost three times higher risk of having a leg ulcer (odds ratio, 2.92; 95% confidence interval (CI), 1.47 to 6.08). In addition, people who had been at high risk of a venous thrombosis but were not diagnosed with this condition (eg, people with a history of major leg surgery) were also at increased risk of ulceration (odds ratio, 2.25; 95% CI, 1.49-3.42). Overall, 56% (95% CI, 33% - 71%) of leg ulcers were attributed to being at high risk of deep vein thrombosis. CONCLUSIONS: Deep vein thrombosis and factors that place people at high risk of deep vein thrombosis are an important cause of leg ulcers in older people. This finding strengthens the rationale for the routine and long-term use of thromboprophylaxis, particularly in high-risk patients.

Adult↗
PubMed1978

Effects of leg exercise on insulin absorption in diabetic patients.

To examine the effects of leg exercise on insulin absorption from various injection sites, 125I-labelled rapid actin insulin (9 units) was injected subcutaneously into the leg, arm or abdomen of patients with insulin-dependent diabetes before one hour of intermittent leg (bicycle) exercise and on a resting, control day. Insulin disappearance from the leg increased by 135 per cent during the first 10 minutes of leg exercise (P less than 0.05) and remained 50 per cent above resting levels after 60 minutes (P less than 0.02). Leg exercise had no effect on insulin disappearance from the arm, but insulin disappearance from the abdomen was reduced during the post-exercise recovery period (P less than 0.02). As compared to leg injection, arm or abdominal injection reduced the hypoglycemic effect of exercise by 57 per cent (P less than 0.02) and 89 per cent (P less than 0.005), respectively. Leg exercise accelerates insulin absorption from the leg. Arm or abdominal injection avoids this acceleration during leg exercise and reduces exercise-induced hypoglycemia.

Abdomen↗
PubMed1998

Prediction of acceptable physical work loads based on responses to prolonged arm and leg exercise.

Nine healthy men (aged 54-59 years) performed arm crank and leg cycle exercises for 30 min at relative work loads of 50 and 75% of peak oxygen uptake (VO2) for the corresponding muscle group, and for 60 min at a relative work load of 30% of peak VO2 for the corresponding muscle group. In the tests, heart rate (HR), blood pressure, gas exchange variables, rating of perceived exertion (RPE) and blood lactate were measured. At the 75% target exercise level, four subjects interrupted the arm-cranking test, and one subject interrupted the leg-cycle test. Owing to differences in peak values during arm-cranking and leg-cycling, the work load and the VO2 were higher during leg-cycling than during arm-cranking. There was no difference in HR between the work modes, but the HR increased to a greater extent during arm-cranking compared to leg-cycling at the 30% (NS) and 50% (P < 0.05) exercise levels. Similarly, the RPE increased more during arm-cranking compared to leg-cycling at each exercise level. The blood lactate concentration was higher after arm-cranking than after leg-cycling; at the 50% exercise level the difference was statistically significant. The results indicate a higher physiological strain with time during arm exercise than during leg exercise at the same muscle group-specific relative work load. The acceptable physical work load, expressed as the percentage peak VO2 for the corresponding muscle group, should thus be lower during arm exercise than during leg exercise. The RPE and the relative HR, expressed as percentage of peak HR for the corresponding muscle group, however, seem to be comparable indicators for the physiological strain during arm and leg exercise.

Arm↗
PubMedDate not supplied

The relationship between short-term changes in weight and lower leg length in children and young adults.

As the knemometer is increasingly being used to study changes in lower leg length in conditions associated with weight changes it is important to clearly delineate the relationship between these two variables. Lower leg length and weight were measured in 26 children and nine adults including one pregnant woman. There was a weak but positive relationship between lower leg length and weight fluctuation in children. Daily fluctuations in weight as well as lower leg length were higher in women than men; median lower leg length fluctuation: women, 0.16 mm (P5-0, P95-0.7); men, 0.1 mm (P5-0, P95-0.48) p approximately 0.02, Wilcoxon signed-rank test. Median weight fluctuation: women 0.15 kg (P5-0, P95-0.54); men, 0.1 kg (P5-0, P95-0.5) p = 0.94 (Wilcoxon signed-rank test). Sustained weight gain in pregnancy led to a reduction in lower leg length followed by an increase which was coincident with the appearance of dependent oedema. Lower leg length changes are likely to be positively related to changes in weight when the latter are only modest in magnitude. However, greater sustained increases in weight are likely to have an opposite effect on lower leg length due to direct compression of the lower leg. Due consideration of weight is essential in longitudinal studies of lower leg length changes, especially in conditions which are associated with significant changes in weight.

Adult↗
PubMed1999

The evoked heart rate response to periodic leg movements of sleep.

STUDY OBJECTIVES: Periodic leg movements of sleep are currently subdivided based upon whether or not they are associated with EEG arousal. "Autonomic" arousals, characterized by elevations in heart rate and blood pressure without AASM-defined EEG changes, have been associated with daytime somnolence in experimental protocols. In this study, we will describe the heart rate response to periodic leg movements of sleep, both with and without associated arousals. DESIGN: Heart rate was averaged for each of the ten cardiac cycles before, and after, the onset of individual periodic leg movements occurring in non-REM sleep for eight patients with Periodic Limb Movement Disorder (PLMD). Records were blindly scored (without EKG data) to determine if AASM-defined EEG arousals occurred within two seconds of leg movement onset. Leg movements during wakefulness were performed by four non-patient controls as a control condition. SETTING: Sleep Disorders Center INTERVENTIONS: None MEASUREMENTS AND RESULTS: A significant rise in heart rate was observed following the onset of individual leg movements of sleep (N = 796), which was also significantly larger than that seen after waking leg movements (N = 275). Although heart rate elevation was 10%-40% higher when leg movements were associated with AASM-defined arousal, these differences did not reach statistical significance. CONCLUSIONS: Periodic leg movements of sleep are associated with cardiac acceleration, even in the absence of AASM-defined arousal. It appears premature to conclude that periodic leg movements of sleep not associated with visible EEG arousal are clinically insignificant.

Adult↗
PubMed1999

Is leg length discrepancy associated with the side of radiating pain in patients with a lumbar herniated disc?

STUDY DESIGN: The association between leg length discrepancy and the side of the radiating pain in lumbar disc herniation was investigated in a case series. OBJECTIVES: To investigate whether pain tends to radiate into the longer or shorter leg in patients with a lumbar herniated disc. SUMMARY OF BACKGROUND DATA: No previous studies have investigated the association between leg length discrepancy and side of radiating pain in patients with a herniated disc. Results of studies of low back pain with radiation and leg length discrepancy are inconsistent concerning this association. METHODS: Of 132 consecutive patients admitted to a district hospital for surgical management of a lumbar herniated disc, leg length discrepancy was assessed using the indirect method as described by Calliet. RESULTS: Seventy-three patients (55%) were men, and 59 (45%) were women. The mean age was 40 years, and 99% of all herniated discs appeared at L4-L5 (n = 60) or L5-S1 (n = 71). In 64 (62%) of the 104 patients with a leg length discrepancy of 1 mm or more, the pain radiated in the shorter leg (P = 0.02). In subgroups of patients with larger leg length discrepancies, similar results were found but because of smaller sample sizes, these findings did not each statistical significance. In 32 of the 57 men (56.1%), the pain radiated to the shorter leg (P = 0.43); this was observed in 33 of the 47 women (70.2%; P = 0.01). CONCLUSION: The results of this study showed a statistically significant association between leg length discrepancy and the side of radiating pain in a case series of patients with lumbar herniated discs. The relation was more pronounced and statistically significant in women only.

Adolescent↗
PubMed1995

Leg design and jumping technique for humans, other vertebrates and insects.

Humans, bushbabies, frogs, locusts, fleas and other animals jump by rapidly extending a pair of legs. Mathematical models are used to investigate the effect muscle properties, leg design and jumping technique have on jump height. Jump height increases with increased isometric force exerted by leg muscles, their maximum shortening speeds and their series compliances. When ground forces are small multiples of body mass (as for humans), countermovement and catapult jumps are about equally high, and both are much better than squat jumps. Vertebrates have not evolved catapult mechanisms and use countermovement jumps instead. When ground forces are large multiples of body mass, catapult jumps (as used by locusts and fleas) are much higher than the other styles of jump could be. Increasing leg mass reduces jump height, but the proximal-to-distal distribution of leg mass has only a minor effect. Longer legs make higher jumps possible and additional leg segments, such as the elongated tarsi of bushbabies and frogs, increase jump height even if overall leg length remains unchanged. The effects of muscle moment arms that change as the leg extends, and of legs designed to work over different ranges of joint angle, are investigated.

Animals↗