Forward Running Research Articles

Forward Running Experiments by Free-Running Model

Free-running experiments are carried out to make clear the stable running of a semi-submersible high speed ship with wings. The ship is an unconventional new type of high speed ship consisting of a main hull, main and tail wings with flaps, and a strut to support the super-structure. The ship floats as a conventional ship but the downward lifting force makes the ship semi-submerged during the operation condition.The model used is a self-propelled free-running model. The carriage follows the model at a constant speed on which all the controllers are placed. Experiments are carried out not only under the calm condition but also among waves of following and head seas, although all the experiments are limited to the forward running tests.Through the experiments it is made clear that the ship can run stably by the control of flaps except under the following sea condition. The induced motions by waves are notably reduced by the submergence. The thrust estimated from the number of revolution of propellers is almost same as the measured resistance and no appreciable increments in the resistance are experienced even among waves. It may be necessary to study more on the flow phenomena and the forces acting on the hull under the following sea condition.Although all the knowledge is limited to the model level, it can be concluded that such an unconventional new type of high speed ship is promising from the hydrodynamic aspects.

Lower extremity joint kinetics and energetics during backward running

The purpose of this study was to measure lower extremity joint moments of force and joint muscle powers used to perform backward running. Ten trials of high speed (100 Hz) sagittal plane film records and ground reaction force data (1000 Hz) describing backward running were obtained from each of five male runners. Fifteen trials of forward running data were obtained from one of these subjects. Inverse dynamics were performed on these data to obtain the joint moments and powers, which were normalized to body mass to make between-subject comparisons. Backward running hip moment and power patterns were similar in magnitude and opposite in direction to forward running curves and produced more positive work in stance. Functional roles of knee and ankle muscles were interchanged between backward and forward running. Knee extensors were the primary source of propulsion in backward running owing to greater moment and power output (peak moment = 3.60 N.m.kg-1; peak power = 12.40 W.kg-1) compared with the ankle (peak moment = 1.92 N.m.kg-1; peak power = 7.05 W.kg-1). The ankle plantarflexors were the primary shock absorbers, producing the greatest negative power (peak = -6.77 W.kg-1) during early stance. Forward running had greater ankle moment and power output for propulsion and greater knee negative power for impact attenuation. The large knee moment in backward running supported previous findings indicating that backward running training leads to increased knee extensor torque capabilities.

Simulation of the voltage dependence of the Na, K pump applied to cardiac cells

We use simulation to study the dependence of the Na, K pump on membrane potential. Two consecutive mechanisms for the Na, K pump, based on a reduced Post-Albers scheme, are examined: one with six steps called GV3 and one with seven steps called MGV3. In GV3, a single voltage-dependent step combines both Na+ translocation and Na+ release into the extracellular medium. In MGV3, these two processes are allocated to two separate consecutive steps, but only the Na+ translocation step is voltage-dependent. Using the optimization software SCoPfit, numerical values of rate coefficients, symmetry factor (beta), and pump site density were found by fitting the models to published experimental data so that both GV3 and MGV3 could quantitatively reproduce steady-state current-voltage relationships for both forward and backward running of the pump, as well as [Na+]in and [K+]out activation curves. Using the rate coefficient values found by SCoPfit, we simulated a voltage-clamp experiment with both models running under their Na(+)-Na+ exchange mode, and we computed the transient currents generated following voltage steps in both depolarizing and hyperpolarizing directions from a basic potential of -40 mV. The voltage dependence of the rate constant (1/tau) of decay of the transient currents could qualitatively be reproduced when beta = 0.884 for GV3, and 0.932 for MGV3. The quantitative discrepancy between published experimental data and the theoretical curve generated by GV3 at potentials more negative than -20 mV was considerably reduced by using model MGV3. This finding alone suggests that a more detailed mechanism containing a single voltage-dependent step may reproduce all major steady-state and transient characteristics of the Na, K pump without the need of a second voltage sensitive step. However, the quantitative discrepancy between published experimental data and the theoretical curve generated by MGV3 at potentials more negative than -60 mV may be fully removed if either beta itself is voltage-dependent, or if a second voltage-dependent step is included in the model.

Forward and Backward Running Waves in the Arteries: Analysis Using the Method of Characteristics

The one-dimensional equations of flow in the elastic arteries are hyperbolic and admit nonlinear, wavelike solutions for the mean velocity, U, and the pressure, P. Neglecting dissipation, the solutions can be written in terms of wavelets defined as differences of the Riemann invariants across characteristics. This analysis shows that the product, dUdP, is positive definite for forward running wavelets and negative definite for backward running wavelets allowing the determination of the net magnitude and direction of propagating wavelets from pressure and velocity measured at a point in the artery. With the linearizing assumption that intersecting wavelets are additive, the forward and backward running wavelets can be separately calculated. This analysis, applied to measurements made in the ascending aorta of man, shows that forward running wavelets dominate during both the acceleration and deceleration phases of blood flow in the aorta. The forward and backward running waves calculated using the linearized analysis are similar to the results of an impedance analysis of the data. Unlike the impedance analysis, however, this is a time domain analysis which can be applied to nonperiodic or transient flow.

Pilot Study: Kinematics, Ground Reaction Force, and Muscle Balance Produced by Backward Running

This study was conducted at the University of Kentucky Biodynamics Laboratory in Lexington, KY and was partially supported by a grant from the Kentucky Chapter of the American Physical Therapy Association. Backward running (BR) is employed for conditioning and for rehabilitation in sports, orthopaedics, and neurology. Our purposes were to compare kinematics and training effects of BR to forward running (FR). Ten runners (6 males, 4 females, ages 20-34 years) were assigned to a backward running (BRG) or control (FRG) group. Subject isokinetic muscular torque production (IMTP) and biomechanics during FR and BR at 3.58 m/sec were studied at the beginning and after 8 weeks of training. Stance time was significantly shorter during BR. The peak vertical component of the ground reaction force (Fz) and Fz impulse were significantly less during BR. After training, knee extensor IMTP of the BRG increased significantly at 75 and 120 degrees /sec. We concluded that BR produced lower Fz stress than FR and improved knee extensor torque at low speeds. Backward running may be clinically useful for reducing stress to injured joints and for increasing knee extensor strength. J Orthop Sports Phys Ther 1989;11(2):56-63.

Mechanical verification of the effectiveness of the first step for quick change of the forward running direction

The gastrocnemius is a biarticular muscle that acts not only as a plantar flexor, but also as a knee flexor, meaning that it is an antagonist during knee extension. In contrast, the soleus is a monoarticular plantar flexor. Based on this anatomical difference, these muscles’ activities should be selectively activated during simultaneous plantar flexion and knee extension, which occur during many activities of daily living. This study examined the selective activation of gastrocnemius and soleus activities when voluntary isometric activation of knee extensors was added to voluntary isometric plantar flexion. Ten male volunteers performed isometric plantar flexion at 10%, 20%, and 30% of maximum effort. During each plantar flexion task, isometric knee extension was added at 0%, 50%, and 100% of maximum effort. When knee extension was added, the average rectified value of the electromyographic activity of the medial gastrocnemius was significantly depressed (P = .002), whereas that of the soleus was significantly increased (P < .001) regardless of the plantar flexion level. These results suggest that plantar flexion with concurrent knee extensor activity leads to selective activation of the soleus and depression of the synergistic activity of the gastrocnemius.

Running Backward May Help Athletes Move Forward

Some competitive and recreational athletes are running backward, believing that the activity will improve their ability to run forward. Crazy? Maybe not. Some researchers are finding that backward running may be an effective adjunct to forward running for both conditioning and rehabilitation.

The differential neurochemical bases of the behaviours elicited by serotonergic agents and by the combination of a monoamine oxidase inhibitor and L-DOPA

The ability of the 5-HT releasing agent, parachloroamphetamine, (PCA) to induce forepaw treading, head weaving and hind limb abduction is not impaired by prior catecholamine depletion with alphamethyl paratyrosine (AMPT). Similarly, the same behaviours elicited by the 5-HT receptor agonist 5-methoxy,N,N-dimethyltryptamine (5-MeODMT) were not antagonized by AMPT. These results argue against the theory that there is a catecholamine link in the mediation of these behaviours elicited by serotonergic drugs. However, the ability of these drugs to induce hyperactivity and hyperreactivity is attenuated by AMPT, suggesting that these components may have a catecholaminergic basis. The same behaviours can be elicited by the combined administration of a monoamine oxidase inhibitor and L-DOPA (MAOI + L-DOPA) which results in a large increase in dopamine synthesis. However, biochemically confirmed 5-HT depletion following parachlorophenylalanine, tetrabenazine and reserpine reduced head weaving, forepaw treading and hind limb abduction while sparing hyperreactivity and hyperactivity. Indeed, parachlorophenylalanine and tetrabenazine mimicked the previously reported effects of 5-HT receptor antagonists in inducing forward running. It is concluded that the similar behaviours induced by PCA, 5MeODMT and MAOI + L-DOPA have differential neurochemical bases. Forepaw treading, head weaving and hind limb abduction are mediated by serotonin and do not involve a catecholamine link whereas hyperreactivity and hyperactivity are not mediated by serotonin. Previous conflicts in the literature may be explained by the different methods used to quantify the behaviours.

Increase in ATP by reversal of the Na-K-pump in mammalian non-myelinated nerve fibres.

1. The intracellular ATP, K, and Na contents during forward and backward running of the Na−K-pump were studied in mammalian non-myelinated nerve fibres. 2. Prolonged incubation in Locke produced little change in the ATP and K content and a slight increase in the intracellular Na. 3. Application of cyanide, iodoacetate, dinitrophenol, and the combination of iodoacetate and dinitrophenol greatly lowered the ATP and K content and strongly increased the Na level. The effects of iodoacetate were partially reversible. 4. Application of ouabain did not change the ATP content, but lowered the K and increased the Na. 5. Application of ouabain in fibres previously exposed to iodoacetate lowered the K level and increased the ATP and Na content, demonstrating the utilization of ATP during the forward running of the Na−K-pump. 6. In order to study the possibility of synthesis of ATP by backward running of the Na−K-pump, fibres exposed to iodoacetate in K-rich Na-free solution were transferred to K-free Locke in the presence of iodoacetate with or without ouabain. In two series of experiments, the preparations exposed to the solution without ouabain showed a significantly higher ATP content. 7. These observations are in accordance with the view that synthesis of ATP is possible by reversal of the Na−K-pump.

Effect of ouabain on the Ca 2+-dependent increase in K + permeability in depleted guinea-pig red cells

1. 1. The hypothesis that the inhibitory action of ouabain on the Ca 2+-dependent increase in K + permeability observed in depleted human red cells is mediated by changes in the intracellular level of ATP was tested by measuring simultaneously the ouabain sensitive K + loss and the concentration of ATP in depleted guinea-pig red cells in the presence and absence of external Ca 2+. 2. 2. The results showed that ouabain has opposite effects on the K + loss. Thus, in the presence of external K +, when the forward running of the Na + pump contributes to the breakdown of ATP, ouabain reduces K + loss, as observed in human red cells; in a K + free, high Na + medium when the pump running backwards induces a net synthesis of ATP (which can be detected in guinea-pig red cells but not in human red cells), ouabain increases K + loss. 3. 3. The results suggest that the action of ouabain is mediated through the changes in the intracellular level of ATP induced by the forward or reverse operation of the Na + pump.

The past, present and future of surgical procedures in Parkinson's disease.

Summary: Effective surgery for the symptoms and signs of Parkinson's Disease began about 1940 when surgery was for the first time directed at the basal ganglia and internal capsule. The initial operations were by open craniotomy and it was not until 1947 that stereotaxic methods originally used by Horsley were applied by Spiegel and Wycis. Their first lesions were made in the ansa lenticu‐laris. From 1953 onwards stereotaxic techniques created lesions in the globus pallidus with success.Irving Cooper working from a different approach started in 1952 to cause lesions by deliberate occlusion of the anterior choroidal artery, the effectiveness of this depended upon the creation of a lesion in the globus pallidus, internal capsule and thalamic region. Cooper perfected a technique for making chemical lesions in the globus pallidus and later in the lateral ventral nucleus of the thalamus and refined this technique by developing a cryoprobe, which had the advantage of making an initially reversible lesion so that with the patient conscious possible complications could be anticipated and avoided.At the present time stereotaxic surgery for Parkinson's Disease is a predictable procedure, having a low mortality provided proper case selection is carried out pre‐operatively.Surgery is effective in abolishing rigidity in 90% of cases and tremor in 75% of cases. It has no effect on the brady‐kinesia and no effect on the bulbar disturbances such as softness of speech or dysarthria. In fact, these may be worsened, particularly in operations on the dominant hemisphere. Disturbances of gait such as locking of gait, slow stumbling gait and disturbances of balance in the form of forward or backward running are not influenced by surgery.The contra‐indications to surgery are dementia, severe bulbar disturbances, particularly diminished voice volume, and poor health. Hypertension is not necessarily an absolute contra‐indication.The ideal candidate for surgery is a patient who is still active and employable, who has rigidity predominantly affecting the intrinsic muscles of the hand and who has predominantly unilateral symptoms and signs. Age is better assessed on the physiological age of the patient rather than on an absolute value and patients in early 70's have been successfully operated upon.Surgery must be directed towards relieving the actual disability of the patient and not merely to the attempted cure of an unsightly tremor. It is likely that there will always be a place for surgery for unilateral disability followed by L‐dopa medication, to control the more generalised features when they arise.

The influence of ions on the labelling of adenosine triphosphate in red cell ghosts

1. The ionic composition of human red cell ghosts and suspending Ringer solutions have been varied independently. Measurements were made of the incorporation of [(32)P]o-phosphate ((32)P(i)) into ATP associated with different concentration gradients of Na and K across the membrane.2. Some incorporation of (32)P(i) was always found irrespective of the ionic composition of ghosts or media. However, additional labelling of energy-rich phosphate occurred when low Na, high K ghosts were incubated in a high Na, K-free medium. This did not occur when there was only a gradient of either Na or K. Downhill movements of both Na into and K out of the ghosts were needed for the extra labelling.3. Even in the presence of suitable ionic gradients, the extra incorporation was prevented by ouabain or by adding a small amount of external K sufficient to facilitate normal operation of the Na pump.4. Increase in internal P(i) stimulated the incorporation.5. The results show that the conditions for forward and backward running of the ATPase system associated with the Na pump are such that both reactions cannot proceed optimally at the same time.