In the case of uniform rotation of a cylindrical vessel around a vertical axis with angular velocity co (Fig. 1.5), the stress vector of mass forces
and Euler’s equation (1.10) has the form
dp = r[w 2 (xdx +ydy) – gdz] = r (w 2 rdr – gdz).(1.52)
Free surface equation (p = p 0)
(1.53)
Equation of any isobaric surface (R= const)
(1.54)
Where z 0- coordinate of the point of intersection of the free surface with the axis of rotation.
Isobaric surfaces are paraboloids of revolution, the axis of which coincides with the axis oz, and the vertices are shifted along this axis. The shape of isobaric surfaces does not depend on the density of the liquid.
Free surface paraboloid height (R - vessel radius)
H = w 2 R 2 /2g.(1.55)
Coordinate z 0 its apex is determined by the volume of liquid in the vessel. If the initial level in the vessel h 0 , That
z 0 = h -(1.56)
where h 1 = h 0 –z 0 = H/2.
Law of pressure distribution in liquid
(1.57)
Rice. 1.5. A cylindrical vessel with liquid rotating at a constant angular velocity w
Vertical pressure change ( h- depth of the point under the free surface):
Р = Р 0 + r gh,
those. the same as in a stationary vessel.
Questions on topic 1.6.
1 . What forces act on a fluid when it is at relative rest?
2. What is the shape of isobaric surfaces in a liquid and the equation that describes them for the rectilinear motion of a vessel with constant acceleration?
3. What is the shape of isobaric surfaces in a liquid and the equation that describes them when the vessel rotates with a constant angular velocity and a vertical axis of rotation?
3. What is the law of vertical pressure distribution in a liquid when it is at relative rest?
Basic concepts of kinematics and fluid dynamics
The speed of a fluid particle depends on the coordinates x, y, z of this particle and time t, those.
Density r and pressure R are also functions of coordinates and time
r = r(x, y, z, t); p = p (x, y, z, t).
If the flow characteristics do not depend on time, i.e. can change only from point to point, then the flow is called steady. If at a given point in space the characteristics of the flow change with time, then the flow is called unsteady.
A streamline is a line at each point of which the velocity vector is directed tangentially to this line. The equations for streamlines have the form
(2.1)
Where and x, and y, u z- components of the velocity vector .
A set of streamlines passing through a closed loop L, forms a tubular surface - a current tube. The liquid inside the current tube forms a stream. If the circuit L is small, then the current tube and stream are called elementary.
Stream cross section s, normal at each point to the streamlines, is called the live section.
A region of space of finite dimensions occupied by a moving fluid is called a flow. A flow is usually considered as a collection of elementary streams. The live cross section of the flow is determined in the same way as in the case of an elementary stream.
Hydraulic radius R g of the live section is defined as the ratio of the area of the live section s to the wetted perimeter c, i.e.
R G = s/c. (2.2)
Under the wetted perimeter c refers to that part of the geometric free section along which the liquid comes into contact with the solid walls.
If the shape and area of the living cross-section along the length of the flow do not change, then the flow is called uniform. Otherwise, the flow is called uneven. In the case when the live cross-section changes smoothly along its length, the flow is called smoothly varying.
In live section 1 - 1 (Fig. 2.1) of a uniform flow, the hydrostatic law of pressure distribution is satisfied, i.e.
(2.3)
Where p A, p B - respectively, pressure at arbitrary points A And IN(with vertical coordinates z a , z b) this section; g- free fall acceleration. In the case of a smoothly varying flow, equality (2.3) is satisfied approximately.
Fluid flow through the surface s is the amount of fluid flowing through this surface per unit time. Volume flow Q, mass flow Q M> weight consumption q G determined by formulas
Where and n- projection of velocity onto the normal to the surface s.
If s- live section, then and n = u. For a homogeneous liquid
Q m = rQ(2.5)
 |
Rice. 2.1. Live cross section of uniform flow
average speed u is determined from the equality
u=Q/s.(2.6)
The continuity equation for an incompressible fluid flow has the form
Q = u 1 s 1 = u 2 s 2 ,(2.7)
Where u 1 , u 2 - average speeds in sections 1 - 1 And 2 - 2.
Bernoulli's equation for an elementary stream of viscous incompressible fluid with steady motion in a gravity field has the form
Where z 1 , z 2- distances from the centers of selected living sections 1 - 1 And 2 - 2 to some arbitrary horizontal plane z = 0(Fig. 2.2); u 1 , u 2 - speed; P1,P2- pressure in these sections; h 1-2- pressure loss in the area between the selected sections.
Bernoulli's equation expresses the law of conservation of mechanical energy. Magnitude
(2.9)
is called total pressure and represents the specific (per unit gravity) mechanical energy of the fluid in the section under consideration; z- geometric pressure or specific potential energy of position; p/(rg)- piezometric pressure or specific potential energy of pressure; u 2 /(2g)- velocity pressure or specific kinetic energy; h 1-2 - pressure loss, i.e. part of the specific mechanical energy spent on the work of friction forces in the area between the sections 1 - 1 And 2 - 2 (see Fig. 2.2).
In the case of an ideal liquid h 1-2 =0.
For a smoothly varying flow with steady motion of a viscous incompressible fluid in a gravity field, Bernoulli’s equation has the form
Where p 1 , p 2 - pressure at arbitrary cross-section points 1 - 1 And 2 - 2 coordinates z 1 And z 2 respectively (usually points on the flow axis are taken); u 1 , u 2- average speeds in these sections; a 1, a 2- Coriolis coefficients, taking into account the uneven distribution of velocities of liquid particles in sections; when flowing through a round cylindrical tube a = 2 for laminar flow regime and a » 1.1- for turbulent; when solving practical problems it is usually accepted a = 1.
When using the Bernoulli equation (2.8) or (2.10), it is necessary to keep in mind that the section numbers increase in the direction of the fluid flow. The sections (streams) in which any of the quantities are known are selected as design ones u 1 , u 2 (u 1 , u 2) And r 1, r 2.
Plane z = 0 It can be convenient to position it so that the center of one of the selected flow sections lies in this plane.
Head loss h 1-2, per unit length of the pipeline, are called hydraulic slope:
(2.11)
In the case of uniform motion of an incompressible fluid
i = h l -2 / l,(2.12)
Where l- distance between selected sections.
When fluid moves through a pipeline, two types of pressure losses are distinguished: losses along the length of the pipeline h d and losses in local resistances h m. Losses along the length include losses in straight sections of the pipeline, and losses due to local resistance include losses in sections of the pipeline where the normal flow configuration is disrupted (sudden expansion, rotation, shut-off valves, etc.).
Questions on topic 2.
1. What is a streamline called?
2. Can liquid flow through the side surface of the current tube?
3. What is called the live cross section of the flow?
4. How does Bernoulli’s equation for a trickle of current differ from Bernoulli’s equation for a flow?
5. What is hydraulic slope?
6. How is the average flow rate determined?
7. What is the relationship between volumetric, mass and weight flow rates?
8. How do the flow rate and average speed change along the length of an uneven flow of incompressible fluid?
Joints are distinguished by the number and shape of the articular surfaces of the bones and by the possible range of movements, i.e. by the number of axes around which movement can occur. Thus, according to the number of surfaces, joints are divided into simple (two articular surfaces) and complex (more than two).
Based on the nature of mobility, there are uniaxial (with one axis of rotation - block-shaped, for example, interphalangeal joints of the fingers), biaxial (with two axes - ellipsoidal) and triaxial (ball-and-socket) joints.
In a spherical joint, one of the surfaces forms a convex, spherical head, the other - a correspondingly concave articular cavity.
Theoretically, the movement can occur around many axes corresponding to the radii of the ball, but practically among them there are usually 3 main axes, perpendicular to each other and intersecting in the center of the head:
1. Transverse (frontal), around which flexion occurs when the moving part forms an angle with the frontal plane, open anteriorly, and extension when the angle is open behind.
2. The anteroposterior axis (sagittal), around which abduction and adduction occur
3. Vertical, around which rotation occurs in and out. When moving from one axis to another, a circular motion is obtained.
The ball and socket joint is the loosest of all joints. Since the amount of movement depends on the difference in the areas of the articular surfaces, the articular fossa in such a joint is small compared to the size of the head. Typical ball and socket joints have few auxiliary ligaments, which determines their freedom of movement.
A type of ball and socket joint is a cup joint. Its articular cavity is deep and covers most of the head. As a result, movement in such a joint is less free than in a typical ball-and-socket joint.
Shoulder joint connects the humerus, and through it the entire free upper limb, with the girdle of the upper limb, in particular with the scapula. The head of the humerus, which participates in the formation of the joint, has the shape of a ball. The articular cavity of the scapula that articulates with it is a flat fossa. Along the circumference of the cavity there is a cartilaginous articular lip, which increases the volume of the cavity without reducing mobility, and also softens shocks and shocks when the head moves. The articular capsule of the shoulder joint is attached on the scapula to the bony edge of the glenoid cavity and, covering the humeral head, ends at the anatomical neck. As an auxiliary ligament of the shoulder joint, there is a slightly denser bundle of fibers that extends from the base of the coracoid process and is woven into the joint capsule. In general, the shoulder joint does not have real ligaments and is strengthened by the muscles of the upper limb girdle. This circumstance, on the one hand, is positive, since it contributes to extensive movements of the shoulder joint, necessary for the function of the hand as an organ of labor. On the other hand, weak fixation in the shoulder joint is a negative point, causing frequent dislocations in it.
Representing a typical multi-axial ball-and-socket joint, the shoulder joint is characterized by great mobility. Movements occur around three main axes: frontal, sagittal and vertical. There are also circular movements. When moving around the frontal axis, the arm produces flexion and extension. Abduction and adduction occur around the sagittal axis. The limb rotates outward and inward around the vertical axis. Bending and abduction of the arm is possible, as stated above, only to the level of the shoulders, since further movement is inhibited by the tension of the articular capsule and the support of the upper end of the humerus into the arch. If the movement of the arm continues above the horizontal, then this movement is no longer performed in the shoulder joint, but the entire limb moves together with the belt of the upper limb, and the scapula rotates with a shift of the lower angle anteriorly and to the lateral side.
The human hand has the greatest freedom of movement. Freeing the hand was a decisive step in the process of human evolution.
An x-ray of the shoulder joint shows the cavitas glenoidalis, which has the shape of a biconvex lens with two contours: the medial one, corresponding to the anterior semicircle of the cavitas glenoidalis, and the lateral one, corresponding to its posterior semicircle. Due to the characteristics of the x-ray picture, the medial contour turns out to be thicker and sharper, as a result of which the impression of a semi-ring is created, which is a sign of normality. The head of the humerus on the posterior radiograph in its inferomedial part is superimposed on the cavitas glenoidalis. Its contour is normally smooth, clear, but thin.
Hip joint. The hip joint is a ball-and-socket joint, has the ability to perform a large range of movements, has pronounced stability, and plays a leading role in maintaining body weight and movement. The head of the femur, located on an elongated neck, penetrates deeply into the acetabulum, which is formed by the connection of the ilium, ischium and pubic bones of the pelvis. The acetabulum is deepened by a fibrocartilaginous lip that forms a “collar” around the head of the femur. The transverse ligament extends through the gap in the lower part of the lip (acetabular notch), thus forming an opening through which blood vessels pass into the joint cavity. The articular cartilage of the acetabulum is horseshoe-shaped and open downwards. The floor of the acetabulum is filled with adipose tissue. Running inside the joint is the round ligament, which starts from the transverse ligament and attaches to the fossa on the head of the femur. The round ligament carries blood vessels and its main function is to nourish the central part of the femoral head. The synovium covers the capsule, labrum, and fat pad, but does not include the round ligament. The hip joint is surrounded by a strong fibrous capsule, which is also strengthened by several ligaments: in front - the iliofemoral (the strongest ligament in the human body), below - the pubofemoral, in the back - the ischiofemoral. There are several bags around the joint: between the greater trochanter of the femur and the gluteus maximus muscle - the greater trochanter, between the anterior surface of the capsule and the iliopsoas muscle - the iliopectineus, above the tuberosity of the ischium and the sciatic nerve - the ischiogluteal. In some cases, the iliopectineal bursa communicates with the joint cavity. In the immediate vicinity of the hip joint, the neurovascular bundle passes in front, and the sciatic nerve passes behind.
Since the hip joint is a spherical joint of the organic type (cup-shaped joint), it allows movement around three main axes: frontal, sagittal and vertical. Circular motion is also possible.
X-rays of the hip joint taken in various projections simultaneously provide an image of the pelvic and thigh bones with all anatomical details.
The glenoid cavity is radiographically divided into a floor and a roof. The bottom of the cavity is limited on the medial side by a cone-shaped clearing, which corresponds to the anterior part of the body of the ischium. The roof of the glenoid cavity is rounded. The articular head has a rounded shape and smooth contours.
A horizontally located disk rotates uniformly around a vertical axis with a frequency of 0.5 s -1. A body lies on the disk at a distance of 0.2 m from the axis of rotation. What should be the coefficient of friction between the body and the disk so that the body does not slide while the disk rotates?
Problem No. 2.4.6 from the “Collection of problems for preparing for entrance exams in physics at USPTU”
Given:
\(\nu=0.5\) s -1 , \(R=0.2\) m, \(\mu-?\)
The solution of the problem:
A body located on a uniformly rotating disk is acted upon by 3 forces: gravity, support reaction force and friction force. Moreover, the latter, if the body is at rest relative to the disk, is the static friction force. In the problem, we consider the limiting case when the static friction force takes its maximum value, i.e. when it is already equal to the sliding friction force, but there is no slipping yet.
Let's write Newton's second law in projection onto the \(x\) axis:
\[(F_(tr.p)) = m(a_ts)\;\;\;\;(1)\]
Taking into account everything written in the first paragraph, the static friction force is equal to:
\[(F_(tr.p)) = \mu N\]
From Newton’s first law in projection onto the \(y\) axis it follows that:
Then the maximum static friction force is:
\[(F_(tr.p)) = \mu mg\;\;\;\;(2)\]
We will find the centripetal acceleration from the following formula using the angular velocity of rotation \(\omega\):
\[(a_ts) = (\omega ^2)R\]
We also write down the formula for the relationship between angular velocity and rotation frequency:
\[\omega = 2\pi \nu \]
\[(a_ts) = 4(\pi ^2)(\nu ^2)R\;\;\;\;(3)\]
Substituting expressions (2) and (3) into equality (1), we obtain:
\[\mu mg = 4(\pi ^2)(\nu ^2)mR\]
The required friction coefficient \(\mu\) is equal to:
\[\mu = \frac((4(\pi ^2)(\nu ^2)R))(g)\]
\[\mu = \frac((4 \cdot ((3.14)^2) \cdot ((0.5)^2) \cdot 0.2))((10)) = 0.2\]
Answer: 0.2.
If you do not understand the solution and you have any questions or you have found an error, then feel free to leave a comment below.
Ministry of Education and Science of the Russian Federation
Federal Agency for Education
State educational institution
Higher professional education
"UFA STATE OIL TECHNICAL
UNIVERSITY"
Department of Water Supply and Sanitation
RELATIVE REST OF THE LIQUID
in a cylinder rotating around a vertical axis
Educational and methodological manual for implementation
laboratory work No. 2
in the discipline "Hydraulics"
for students of specialties
270112 “Water supply and sanitation”,
270102 “Industrial and civil construction”,
270205 "Highways"
all forms of education
The educational and methodological manual was prepared in accordance with the current work program of the discipline “Hydraulics” and is intended to develop students’ independent work skills.
This teaching guide introduces students to the basic concepts of the “Hydrostatics” section
Compiled by Lapshakova I.V., Associate Professor, Candidate of Sciences. tech. sciences
Reviewer Martyashova V.A., Associate Professor, Candidate of Sciences tech. sciences
© Ufa State Petroleum Technical University, 2012
1. GENERAL INFORMATION
The relative rest of a liquid in rotating vessels is often encountered in practice (for example, in separators and centrifuges used to separate liquids, as well as in devices for determining and regulating speeds). In this case, as a rule, two types of problems are solved. The first task is related to the calculation of the strength of the vessel walls. To do this, you need to know the law of pressure distribution in a liquid. The second task is related to calculating the volume and overall dimensions of a vessel (for example, a liquid tachometer). In this case, you need to be able to calculate the coordinates of points on the free surface.
The liquid is in a cylinder rotating around a vertical axis with an angular velocity w.
With uniform rotation of a cylinder with liquid around a vertical axis, after some time the liquid begins to rotate along with the vessel, i.e. comes to a state of relative peace. In this state, there is no displacement of the liquid particles relative to each other and the walls of the cylinder, and the entire mass of liquid with the cylinder rotates as a solid body.
To solve these problems, we will use a rectangular coordinate system rigidly connected to the cylinder. Let's place its beginning at the point of intersection of the bottom of the cylinder with its axis. Let us apply the basic equation of hydrostatics in differential form to the fluid:
Where dP– total pressure differential at a given point;
X, Y, Z– projections of unit mass forces (projections of accelerations) onto the corresponding coordinate axes;
r– liquid density.
Let us take particle A in a rotating fluid (Fig. 1), located at a distance r from the axis of rotation of the cylinder. On this particle perpendicular to the axis Z centrifugal force of inertia acts with acceleration w 2 r, whose projection onto the axis X
Figure 1 – Design diagram
Likewise for the axis OU
Acceleration acts along the OZ axis Z=-g
Let's substitute the found values X, Y, Z into equation (1)
Integrating (2), we find
(3)
Assuming , we obtain from expression (3) the equation of isobaric surfaces
. (4)
As can be seen, these surfaces are congruent paraboloids of rotation with the Z axis, at all points of which the pressure is constant. Such surfaces are called level surfaces. One of them is the free surface of the liquid. Let us denote by z 0 the coordinate of the vertex of the free surface paraboloid (see Fig. 1). Since at the vertex of the paraboloid
the free surface equation will be written in the form
, (5)
Where z sp– coordinate of the free surface of the liquid.
Considering that
,
. (6)
,
Paraboloid height
Angular rotation speed
Substituting (8) into expression (7) we find the number of revolutions
Therefore, the impacting cylinder, partially filled with liquid, can be used as a revolution counter (tachometer).
Such liquid tachometers were very widespread before the creation of electric and electronic tachometers, which had a number of advantages over liquid ones.
If the external pressure in the cylinder is equal to p 0 then, setting in equation (3)
find the integration constant
Then the law of pressure distribution in the liquid will be expressed by the formula
. (10)
For an arbitrary point M located below the coordinate z 0, the pressure will be determined
,
Since the value 
, equal to h m (see Fig. 1), represents the depth of immersion of point M under the free surface, then we can write
, (11)
Those. in this case, the linear (hydrostatic) law of pressure distribution over depth, which is measured from a curved, free surface, is valid.
2. PURPOSE OF THE WORK
2.1. Visual observation of the shape of the free surface of a liquid in a rotating cylinder.
2.2. Study of the laws of relative rest necessary for the design of centrifuges, liquid tachometers and other devices.
2.3. Assessing the accuracy of liquid tachometer readings.
3. DESCRIPTION OF THE EXPERIMENTAL INSTALLATION
The installation (Fig. 2) consists of a glass cylinder2 , inserted into holder 1. The cylinder is driven into rotation through a V-belt transmission from an electric motor, which is connected to the electrical network through a rheostat, which allows you to change the engine speed. Next to the cylinder there is a coordinate ruler 3 with a movable measuring needle 4, with the help of which the coordinates are measured z n And z 0. A frequency meter is installed to determine the number of cylinder revolutions. In addition, the number of revolutions can be determined by the number of clicks produced by the needle 5 when it touches the protrusion on the disk 6.
Figure 2 – Installation diagram
4. ORDER OF WORK
4.1. Fill the cylinder with colored liquid to approximately 1/3 of its height.
4.2. Measure the radius of the cylinder R and the level of liquid in it z n.
4.3. Turn on the engine. Use the rheostat motor to set the cylinder speed at which the height of the paraboloid will be maximum. In this case, you need to make sure that the top of the paraboloid does not touch the bottom of the cylinder or water does not overflow over its top.
4.4. Wait (it is very important not to rush here, otherwise the accuracy of the measurements will be low) until the relative rest of the liquid in the cylinder is established, i.e. the height of the paraboloid will stop changing and measure the coordinate z 0 using a coordinate ruler.
4.5. Determine the number of revolutions from the counter reading or the number of clicks per unit of time.
4.6. Reduce engine speed slightly using a rheostat. Repeat measurements according to points 4.4 and 4.5.
4.7. Carry out 5-6 experiments at different speeds.
4.8. Enter the measurement results in the table.
5. CALCULATION FORMULAS
5.1. Determine the difference in readings z n – z 0.
6.2. Determine the number of revolutions using formula (9).
6.3. Calculate the number of cylinder revolutions from the clicks (revolution counter).
6.4. Determine the error by comparing the calculated number of revolutions , with measured p:
6.5. Enter the calculation results into the table.
Table 1
Calculation results
6.1. Write down the purpose of the work.
6.2. Draw and describe the installation.
6.3. Write down the calculation formulas.
6.4. Provide a completed table of observations and calculations.
6.5. Draw a conclusion about the work done by assessing the error in measuring the speed with a liquid tachometer.
7. SELF-TEST QUESTIONS
7.1. What is relative peace?
7.2. What forces act on a fluid that is at relative rest in a cylinder rotating around a vertical axis?
7.3. Write the basic equation of hydrostatics in differential form. What's happened X, Y, Z?
7.4. What is a unit mass force? What is the physical meaning?
7.5. Why when assessing X, Y, Z are we not taking into account the Coriolis acceleration?
7.6. What is a level surface?
7.7. Write down the differential equation for the free surface of a liquid?
7.8. How to determine the pressure at any point in a liquid located below the free surface in a vessel rotating around a vertical axis
7.9. How will the shape of the free surface change if, at a constant number of revolutions, we replace water with mercury; gasoline, viscous machine oil? What effect does the viscosity and density of a liquid have on the shape of the free surface?
7.10. Where in technology is the law of relative rest applied? What device parameters can be calculated using these patterns?
7.11. What would the shape of the free surface look like in a rotating fluid-filled and closed cylinder? How will the pressure be distributed along the bottom and lid of such a cylinder?
7.12. How to determine the pressure at any point of a rotating annular mass of liquid located between two cylindrical surfaces?
BIBLIOGRAPHY
1. Shterenlikht, D.V. Hydraulics [Text]: textbook. for universities / D. V. Shterenlikht. - 3rd ed., revised. and additional - M.: KolosS, 2007. - 656 p. : ill. - (Textbooks and teaching aids for university students).
Human biomechanics is an integral part of the applied sciences that study human movement.
Planes.
To designate the positions of the human body in space, the location of its parts relative to each other, the concepts of planes and axes are used.
Sagittal plane separates the right and left halves of the body. A special case of the sagittal plane is the median plane; it runs exactly in the middle of the body, dividing it into two symmetrical halves. (red in the figure, sagittal plane)
Frontal plane-separates the front part of the body from the back. It is located vertically and oriented from left to right. Perpendicular to the sagittal plane (blue in the figure, coronal plane)
Horizontal plane- or transverse plane, perpendicular to the first two and parallel to the surface of the earth, it separates the overlying parts of the body from the underlying ones. (green in the figure, transverse plane)
These three planes can be drawn through any point of the human body. When two mutually perpendicular planes intersect, an axis of rotation is formed.
Axes of rotation:
Vertical axis– formed at the intersection of the sagittal and frontal planes. Directed along the body of a standing person.
Around this axis, pronation, supination, and rotation of the torso and head are possible.
Front axis– formed at the intersection of the frontal and horizontal planes. Oriented from left to right or right to left. Flexion and extension occur around this axis.
Sagittal axis– formed at the intersection of the sagittal and horizontal planes. Oriented in the anteroposterior direction. Abduction and adduction, elevation and descent of the shoulder blades, and lateral flexion of the torso occur around this axis.
To analyze exercises, it is very important to know the names of the movements and understand in which joints they are performed.
Movement names:
Supination-outward rotation
Pronation - inward rotation
Adduction-reduction, adduction
Abduction-breeding, abduction
Circumduction - circular rotation.
| Joint/body segment | Possible movements |
| spine | Sagittal axis - lateral flexion/extension (bending to the side) Frontal axis - flexion/extension Vertical axis - rotation |
| Sternocostal joints | motionless |
| Joints of the head of the ribs and costotransverse joints | Rotation along the axis of the rib neck. The upper ribs move mainly forward, the lower ribs mainly to the sides. |
| Sternoclavicular joint | Sagittal axis - raising\lowering the shoulder girdle. Frontal axis - rotation of the clavicle around its axis Vertical axis - movement of the shoulder girdle forward/backward |
| Shoulder joint | |
| Wrist joint | Sagittal axis - abduction/adduction Frontal axis - flexion/extension |
| Hip joint | Sagittal axis – abduction/adduction Frontal axis – flexion/extension Vertical axis – pronation/supination |
| Knee-joint | Frontal axis - flexion/extension Vertical axis - rotation (only in a bent position) |
| Ankle joint | Frontal axis - flexion\extension |
Movements in the joints
| GENERAL MOVEMENTS | Plane | Description | Example |
| Lead | Frontal | Movement directed from the midline of the body | Abduction of the leg at the hip joint |
| Bringing | Frontal | Movement towards the midline of the body | Adduction of the leg at the hip joint |
| Flexion | Sagittal | Reducing the angle between two structures | Pulling the forearm to the shoulder, curling the arms with dumbbells for the biceps |
| Extension | Sagittal | Increasing the angle between two structures | Straightening the arm, returning to the starting position in the same exercise |
| Inward rotation | Horizontal | Rotation of the bone around a vertical axis towards the midline of the body | Bringing your hands together on the upper block |
| Outward rotation | Horizontal | Rotation of the bone around a vertical axis in the direction from the median; body lines | Heels in and toes out |
| Full rotation | All planes | Full rotation of the limb at the shoulder or hip joint | Circular rotation with arms |
| SPECIFIC MOVEMENTS | |||
| 1. Ankle joint | |||
| Plantar flexion | Sagittal | Sock pulling | Standing calf raise |
| Dorsiflexion | Sagittal | Bringing the toes to the shin | Standing calf raise (reverse movement) |
| 2. Wrist joint | |||
| Pronation | Horizontal | Rotate the forearm palm down | Unscrewing the nut |
| Supination | Horizontal | Rotate the forearm palm up | Screwing the nut |
| 3. Shoulders | |||
| Lowering | Frontal | Downward movement of the shoulder blades | Stabilization of the shoulder girdle, for example, when performing a “corner” on the forearms |
| Lifting | Frontal | Upward movement of the shoulder blades, for example. with a shrug | Seated dumbbell press (upward movement) |
| Breeding | Horizontal | Movement away from the spine | Seated chest row (starting position) |
| Mixing | Horizontal | Movement towards the spine | Seated chest row (final position) |
| Inward rotation | Frontal | The upper edge of the shoulder blades deviates outward, and the lower edge inward | Wide grip pulldown |
| Outward rotation | Frontal | The upper edge of the shoulder blades deviates inward, and the lower edge outward | |
| 4. Shoulder joint | |||
| Horizontal abduction/extension | Horizontal | Movement of the arm raised to the side backwards | Raising arms while lying on a bench |
| Horizontal adduction/flexion | Horizontal | Movement of the raised arm to the side forward | Same exercise, return to starting position |
| 5. Spine | |||
| Lateral flexion | Frontal | Deviation of the body from the vertical axis to the side | Side bends while sitting on a gymnastic ball |
During training, muscles are destroyed, and then they go through recovery phases.
According to scientific data, there are three main phases of recovery after training:
· the first phase is the recovery phase, during which tissue repair occurs, during this period the function is restored to its original level
· second phase – supercompensation, during which increased performance is observed, which can exceed the initial level by 10 - 20%
· third phase – phase of gradual return to the original level of performance.
To solve the problem with a number of parameters, supercompensation of which occurs at different moments, it is proposed to divide the training program into microcycles, where each microcycle is responsible for the development of a certain parameter. The simplest solution is split training which should be performed in different intensity modes. That is, each muscle group should be trained at varying degrees of intensity from one session to the next: light - medium - high - and so on. Thanks to this approach, it is possible to maintain different parameters in the compensation phase and prevent the development of adaptation to loads.
Training plateau- this is a state of the athlete’s body in which the growth of certain physical parameters (strength, muscle mass, endurance, etc.) stops as a result of muscular adaptation to stereotypical loads. It has been clearly proven that muscle hypertrophy occurs only if the stimulating factor is unfamiliar to the muscles. An “unusual factor” means an overload or a load that exceeds the previous level. To create an overload in bodybuilding, a simple technique is used: progressively increasing weights in each workout.
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