General and Sports Anatomy - L.V. Kapilevich, K.V. Davletyarova 2008

Dynamic Morphology
Specific Dynamic Morphology

Anatomical Characteristics of Body Positions

✵ Spatial orientation: vertical, horizontal, inclined.

✵ Posture: arrangement of body parts.

✵ In relation to support: upper support, lower support.

✵ Positions can be: static — gravity and support reaction forces are balanced, or dynamic; symmetrical or asymmetrical depending on the load distribution on the right and left sides.

✵ Balance: unstable, conditionally stable.

External forces may act in: compression, tension, bending, torsion.

Standing Position. This is the most natural position, which can serve as a working posture, as well as the starting and ending position for exercises. It is a position with lower support. To maintain balance, the COM must be positioned directly above the support area.

Three types of standing positions:

1. Anthropometric. The body is shifted slightly backward, and the axis passes through the main JOINTS OF THE lower limbs. This position is somewhat inconvenient because the Muscles of the anterior lower leg are under greater strain; they are weaker and fatigue quickly.

2. Relaxed — the most comfortable position (at ease). The torso is slightly leaned back, and the pelvis is pushed forward. The line of gravity lies anterior to the ankle joint axis and posterior to the pelvic joints, passing through the knees. Muscle tension is minimal, primarily involving the anterior thigh and posterior lower leg muscles.

3. Stiff posture (attention). The torso is straightened and brought forward, the line of gravity is anterior to all joint axes, and the posterior muscle groups are under tension.

Handstand

A vertical, upside-down position with lower support.

The support area is small (the surface area of the hands and the space between them), and the COM is high (conditionally stable balance). Lower limbs: gravity tends to cause flexion at the knee and hip joints, so extensor muscles are engaged; conversely, the FOOT is extended, requiring the action of flexors.

Spinal muscles: tone increases in the extensors of the thoracic region and the flexors of the lumbar region.

Since the Pectoral Girdle is an open kinematic chain, the joints lack a bony block in this position; therefore, it is maintained by the muscles that normally elevate the shoulder girdle (sternocleidomastoid, levator scapulae, trapezius). Back muscles stabilize lateral movements. The upper limb Functions with a distal support. At the wrist joint, all forearm and hand muscles are engaged, with the flexors of the wrist and fingers stretched. Gravity flexes the elbow joint, so the extensors are active. The HEAD is extended at the atlanto-occipital joint to shift the COM backward.

Respiration is impeded because thoracic breathing is almost entirely suppressed — the muscles fix the shoulder girdle; abdominal breathing is also restricted due to tension in the abdominal wall and the Diaphragm being compressed by the weight of the Internal Organs.

Venous return from the head is impaired because the Veins OF THE head lack Valves.

This exercise promotes The Development of strength in the upper limbs, abdomen, and back, as well as movement coordination.

Straight-Arm Hang

The body is in a vertical position with upper support in stable equilibrium (COM lies below the support area), and gravity acts as a tensile force (directed downward). The Hip and knee joints are extended, while the ankle joint is flexed.

The arms may be pronated (thumbs pointing toward each other) or supinated. The primary load falls on the flexors of the wrists and fingers, which support the body weight.

The Muscles of the Upper Limb work to stabilize the joints. In the elbow joint, the load is alleviated by the olecranon process locking into the trochlea of the humerus. This is not the case in the shoulder joint — the entire load is borne by the muscles that depress the shoulder girdle (primarily the triceps brachii).

The lower limb muscles operate with a proximal support; the load on them is minimal, and the tone of the flexors is slightly elevated because gravity tends to cause extension.

In the trunk region, both the extensors and flexors (Abdominal muscles) are contracted to stabilize the pelvis.

Breathing is labored because the muscles that elevate the Ribs are stretched and the chest is expanded; inhalation occurs mainly via the diaphragm, though its excursion is also limited due to increased lumbar lordosis and tension in the abdominal muscles.

The most biomechanically efficient grip is with hands shoulder-width apart, as this minimizes the load on the shoulder girdle muscles.

A wide grip increases the load on the rhomboid and trapezius muscles required for scapular retraction.

A narrow grip stretches the muscles of the shoulder girdle and reduces their strength.

The hanging position promotes the Development of the upper extremity, back, and abdominal muscles, and helps correct posture defects.

Hang with bent arms

Similar to the previous position, but with increased tone in the forearm flexors—specifically the brachialis and brachioradialis (which support the entire body weight).

Since this is an upper support position, shoulder flexion occurs relative to the forearm. The body is inclined to maintain balance, as the center of gravity (COG) is located beneath the point of support.

Breathing is even more restricted due to higher tone in the abdominal press muscles.

Arched hang

A vertical upside-down position. The hands are fixed to the apparatus and positioned along the torso; the legs are straight with pointed toes.

The Muscle Action of the free upper extremity is similar to that in a straight-arm hang.

There is increased tone in the muscles that elevate the shoulder girdle. Overall balance is stable (since the COG is below the support), but the balance of individual body segments is not—the legs and pelvis are in unstable equilibrium relative to the shoulder girdle, which serves as the support.

Breathing relies on the movement of the lower ribs. The displacement of internal organs is similar to that in a handstand.

Foot hang

Support is provided by the dorsal surfaces of the feet. The primary load falls on the anterior compartment of the leg and the dorsum of the foot (extensors of the foot and toes). Hanging with bent legs is significantly easier because the load is borne by the stronger leg flexors (with a lifting capacity of around 500 kg).

Support on parallel bars

The body is in a vertical position, arms are straight along the torso, and the hands are fixed to the apparatus.

A mixed support position: the arms have a lower support, while the torso, head, and legs have an upper support (via the shoulder girdle). The COG for the arms is above the support (conditionally stable equilibrium), while for the body, it is below the support (stable equilibrium). Gravity exerts a compressive force on the arms and a tensile force on the torso and legs.

The wrist is passively extended (by gravity), with weight resting on the wrist joint. Muscles stabilize the radiocarpal joint. In the elbow joint, gravity tends to cause flexion, resulting in increased tone in the forearm extensors.

The shoulder girdle rests on the heads of the humerus.

There is increased tone in the adductors of the shoulder and the depressors of the shoulder girdle, as well as the pectoralis major and latissimus dorsi.

Regarding the lower limbs and trunk, there is elevated tone in the extensors of the trunk and legs, as well as the foot flexors. The chest is expanded, and breathing is diaphragmatic.

Support on rings places an additional load on the shoulder adductors, especially when the arms are abducted (the "iron cross"), due to the increased lever arm of gravity and torque.

They contribute to the development of the muscles of the upper extremities and back.

Gymnastic bridge

A backward-bending arch. The COM is located below the spine and above the base of support. The base of support is large, and the degree of stability is significant. Flexion occurs in the ankle and knee joints, while extension takes place in the hip joint, spine, shoulder, and elbow.

The thoracic Kyphosis is reduced, whereas the lordoses are, by contrast, increased.

On wall bars, the bridge can be performed with a greater backbend. All joints of the upper limbs are maximally extended. The muscles counteract not the force of gravity, but rather the tension (elasticity) of the ligaments and opposing muscles.

The anterior muscle group of the thigh prevents knee flexion.

The triceps brachii prevents flexion at the elbow joint.

The chest is expanded and exhalation is difficult—only the lower ribs are active, while the diaphragm, conversely, remains in the exhalation position because the abdominal wall pushes internal organs against it, preventing it from participating in exhalation.

The exercise develops the elasticity of ligaments across all joints.

Anatomical characteristics of body movements

Movements:

✵ translational;

✵ rotational.

Walking

A complex cyclic movement involving pushing off from a surface and propelling the body through space.

A key feature of walking is the continuous maintenance of support.

Stepping movements form The basis of walking.

Stepping one leg forward from a standing position constitutes a simple step. Bringing the second leg forward constitutes a single step, which comprises two parts: the back step (the leg moves from behind toward the COM plane) and the front step (the leg moves forward from the COM plane).

Alternating between both legs forms a double step, returning the body to its starting position. A double step comprises four simple steps, yet its length equals three (due to the overlap of a simple step from one leg with that of the other). The right side of the body mirrors the Movements of the left side with a phase shift of $\frac{1}{2}$ cycle, representing an asynchronous-symmetrical movement.

There are two types of support: double support, where the front foot rests on the heel and the rear foot on the toe; and single support, relying on only one foot. One leg acts as the supporting limb, while the other

- serves as the swing or recovery limb. Additionally, one leg is positioned forward while the other is positioned backward.

The arms perform swinging motions, with one arm positioned forward and the other backward.

A double step consists of six phases (Figure 24):

1. Forward step of the supporting leg — the leg moves forward and lands from heel to toe. The body experiences an impact, which is cushioned by flexion at the knee joint. The anterior muscles of the lower leg contract to stabilize the ankle joint, while simultaneously the extensors of the lower leg (the anterior muscle group of the thigh) contract.

2. The vertical alignment phase of the supporting leg. The leg bears weight on the entire foot during a very brief phase. The extensors of the lower leg and the hip adductors are engaged to prevent lateral Displacement of the pelvis toward the unsupported leg.

3. Backward step of the supporting leg. The leg moves away from the support, starting with the heel. The movement finishes with a push-off: the foot flexes, and the lower leg and thigh extend. Muscles involved include the plantar flexors of the foot, the posterior calf muscles, and the anterior thigh muscles. These muscles operate on the lower support and act over a large attachment area, thereby increasing force. The movement concludes with a backward push directed forward and upward.

4. Backward step of the swing leg. The swing leg flexes at the knee and ankle joints. The anterior thigh muscles contract—working on the upper support and moving the leg forward. The posterior thigh group flexes the leg at the knee, while the anterior lower leg group extends the foot so the toe does not Touch the ground.

5. Vertical phase of the swing leg. The leg is slightly flexed at the knee and extended at the ankle joint.

6. Forward step of the swing leg. Thigh movement decelerates as the knee joint extends (quadriceps femoris). The muscles work with proximal support, resulting in lesser force. After heel strike, the cycle ends, and the lower leg is straightened. The first phase of one leg coincides with the fourth phase of the other, and so on. The ground reaction force is divided into two components: support rigidity and friction. If either of these forces is weak (snow, sand, ice), walking becomes extremely difficult. Gravity acts as a braking force when lifting the leg and a propulsive force when lowering it. The center of gravity (CG) performs sinusoidal movements: lowest during double support, highest during single support, with an amplitude of 4-6 cm. The CG also undergoes lateral oscillations because it is positioned over the axis of the supporting leg (these oscillations decrease as walking speed increases), which is related to inertia. During the forward step, the torso leans forward; during the backward step, it leans backward. Simultaneously, torso rotation occurs: the shoulder girdle turns toward the supporting leg. These movements are caused by inertia, and the corresponding muscles counteract them: back muscles for forward lean, and abdominal muscles for backward lean. Upper limb movement is out of phase with the legs, which dampens body rotation during the push-off of the rear leg. The respective arm muscles resist these movements. A step lasts 0.5 seconds at a cadence of 100-120 steps per minute; fast walking reaches 170 steps per minute, and at a tempo of 190-200 steps per minute, it transitions into running. Step length is 76-79 cm, and speed is 1.5 m/s.

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Figure 24. Phases of walking.

1, 2, 3, 4 - forward step of the supporting leg (right), 5 - vertical phase of the supporting leg; 6, 7, 8, 9 - backward step of the supporting leg, 10 - backward step of the swing leg, 11 - vertical phase of the swing leg, 12 - forward step of the swing leg

Special Types of Walking

Crouch walking.

This is a more evolutionarily ancient type of walking and is more energy-efficient (characteristic of Neanderthals). Speeds can reach up to 10 km/h; it is advantageous when carrying loads or walking through snow.

The torso is strongly inclined forward, and the legs are flexed in all phases except when the leg is the rear support.

Gravity facilitates forward movement, while longer steps prevent falling. The CG is lower, the feet are placed parallel onto the full sole simultaneously, the cadence is higher, and CG oscillations are smaller.

The foot is extended, while the knee and hip joints are flexed, stretching muscles and ligaments that act like a spring during push-off, which occurs at a sharper angle.

Placing the foot flat on the sole prevents forward movement of the CG from slowing down. The muscles bear a heavier load, especially the quadriceps femoris, which remains contracted for virtually the entire cycle, alternately performing holding and overcoming work. The gluteus maximus is continuously contracted to maintain the forward-leaning posture, leading to rapid muscle fatigue.

Race walking.

The lower limb remains almost entirely extended at the knee joint throughout (with only slight flexion in the swing leg). Landing occurs on the heel with a straight leg, resulting in significantly less Shock absorption.

The torso is erect, the head is tilted slightly back, the shoulder girdle is elevated, and the shoulders are retracted. The double-support period is minimal. Step length is up to 130 cm, at 200-210 steps per minute. Speed = 15 km/h.

The pelvis drops slightly toward the swing leg, and at the vertical moment, the load on the hip abductor muscles increases.

Ozolin notes that many athletes exhibit hyperextension of the supporting leg at the knee joint, which creates an additional "backward" push.

Pelvic rotations toward the supporting leg lengthen the step, and vertical oscillations of the CG are reduced, thereby increasing movement speed. The arms are bent at the elbows, with a large amplitude of movement.

Walking backward.

The torso is strongly inclined forward, with significant forward and backward sway. Landing occurs on the toe, as does the lift-off. The double-support period is prolonged, and speed is reduced. At the vertical moment, complete extension of the knee joint occurs. The posterior thigh muscle group is active in the swing leg.

Walking against resistance (e.g., a headwind).

The body is inclined forward, with the CG outside the support area (the body does not fall due to the resistance). During the double-support period, both feet are flat on the ground. This period is prolonged while the single-support period is shortened, resulting in a reduced step length.

Body weight is utilized to overcome resistance, accompanied by smaller CG oscillations. The swing leg lands with the hip and knee joints flexed, followed by extension up to the vertical moment.

The greatest load falls on the anterior thigh muscles and the posterior calf muscles (since toe support is stronger, friction must be increased). The posterior spinal muscles prevent the body from falling forward.

Walking on stairs (inclined plane).

Upward:

✵ the double-support phase is prolonged;

✵ the free leg moves in a flexed position;

✵ the supporting leg straightens after the vertical moment.

Maximum load is placed on the quadriceps femoris, which lifts the body upward. During the single-support phase, the foot is placed flat On the surface, and on a steep incline, on the toes. Forward locomotion is driven by movements in the ankle joint.

There is less oscillation of the pelvis and spinal Column, resulting in reduced muscle workload.

Downward:

Gravity assists the movement. The vertical moment and forward step are more pronounced. The torso and arms are tilted backward to maintain balance. The foot is placed on the toes (stairs) or the heel (inclined plane).

Then, under the force of gravity, the knee and hip joints flex; consequently, the extensor muscles perform yielding work (the quadriceps femoris and the posterior calf muscle group). The anterior trunk muscles prevent backward falls.

Walking on tiptoe.

The entire body is in a tense, upright position; thoracic kyphosis is reduced, while lumbar lordosis is increased. The foot is fully flexed at the ankle joint, with the posterior calf muscles acting as shock absorbers. The COM is higher, and the support area is smaller in the anteroposterior direction, which decreases body stability, though stability increases with longer toes.

The lower leg is fixed at the knee and ankle joints, meaning these muscles perform static work.

All movements occur in the hip joint. The step length is short, but it promotes the development of lower extremity muscles, The formation of posture, and The ability to maintain balance.

Running

The movement cycle resembles walking, involving the same forces and muscle groups. There is no double-support phase, but a flight phase is present. Push-off is faster and at a sharper angle, with the arms bent at the elbows. The torso lean is significant and proportional to the running speed. The vertical COM is energetically shifted beyond the support base, especially against a headwind.

The movement begins by shifting the COM forward, initiating a fall; at this moment, the push-off by the rear leg starts the flight phase (replacing the double support). This is followed by landing on the leg extended forward.

Upon landing, the leg is partially flexed at the knee joint (for shock absorption).

Landing may occur:

✵ on the forefoot (at high speeds). This results in a longer stride and greater shock absorption, but increases stress on the plantar flexors and toe flexors that execute the push-off, meaning they do not get to rest and fatigue quickly.

✵ on the heel (at low speeds). This provides poor shock absorption and a heavy impact.

✵ on the lateral edge of the foot (which is better than landing on the heel), though this requires relaxing all calf muscles during the flight phase—a skill possessed only by skilled athletes.

The foot position is parallel or even angled inward, allowing not only the posterior but also the lateral muscle groups to be utilized for the push-off.

During running, the torso performs movements similar to walking, but the higher the speed, the smaller their amplitude. Arm swing amplitude is large, and the arms do not fully straighten. Muscle Function is similar to walking. The COM is at its lowest point during the vertical moment and at its highest when the legs are spread farthest apart. Average speed = 4.6 – 5.9 m/s (for untrained individuals). Stride length is 159–129 cm, and up to 168 cm for long-distance runners. Cadence reaches up to 20 double strides per second. Sprinting relies on strength, while distance running relies on endurance. The 400 m event is a combination of both qualities. Athlete qualification is reflected more in stride length than in cadence.

Standing long jump

A complex, acyclic, translational movement that is simultaneously symmetrical, involving the body's takeoff from a supporting surface, flight, and landing.

The COM traces a parabolic trajectory (similar to a projectile throw).

For an optimal jump, it is essential that all body parts remain motionless relative to each other at the moment of takeoff; otherwise, a portion of energy is wasted.

Forces involved: gravity acts throughout all phases, while ground reaction force is present in all phases except flight.

I. Preparatory phase.

Initiated in a squat. Plantar flexion occurs at the ankle joint, along with flexion at the knee and hip joints. The body shifts forward, the COM moves beyond the base of support, and the fall begins.

II. Takeoff phase.

Involves dorsiflexion/plantar flexion at the ankle, extension at the knee and hip joints, and an upward arm swing (which elevates the COM).

Theoretically, maximum distance is achieved at a takeoff angle of 45⁰. In reality, however, the maximum is about 30⁰, because a steeper angle results in a loss of takeoff velocity due to anatomical constraints—at such an angle, the muscles would lose contraction speed. The feet are positioned at an angle to engage the Lateral Muscle Group of the lower leg.

The active muscles include the plantar flexors of the foot, the posterior and lateral muscle groups of the lower leg, the quadriceps (anterior thigh muscles), the posterior hip muscles, and the spinal extensors. All of them perform overcoming work against gravity.

At the moment of near-complete extension, antagonists engage to lock and stabilize all joints.

III. Flight phase.

The trajectory is predetermined (it can only be altered by external forces). Muscles relax. Flexing the legs can ensure a further landing. The arm swing at the moment of takeoff raises the COM and extends the flight phase. During flight, the body rotates around the COM (since the leg drive imparts angular momentum), and by the time of landing, the legs are brought forward.

IV. Landing phase.

Landing occurs on the heels, with shock absorption achieved through flexion at the knee and hip joints, while the respective muscles perform yielding work. The COM is positioned backward, but backward falls are prevented by the inertia of the upper body. Inhalation occurs at the moment of takeoff (arm raise), and exhalation upon landing.

Rotational movements

The force must be applied at a certain distance from the COM rather than directly through it, creating a torque equal to the product of the force magnitude and the moment arm (the distance between the axis of rotation and the point of force application).

Every body possesses inertia; accordingly, in rotational motion, resistance is roughly equivalent to the moment of inertia M = mr, where m is mass and r is the radius of rotation.

Consequently, the farther a point (or body segment) is from the axis of rotation, the greater the M. Therefore, by bringing body parts closer to the axis of rotation, one can decrease M and consequently increase the angular velocity of rotation. During a pirouette, pulling the limbs in reduces M by a factor of 7, and during a salto (somersault) by a factor of 3.

Standing back salto

A complex acyclic rotational movement.

I. Preparatory phase.

Starting position is a semi-squat. Plantar flexion occurs at the ankle joint, flexion at the knee and hip joints, and trunk flexion, with the arms slightly bent at the elbows and extended at the shoulders.

The muscles act primarily as antagonists, performing holding work (movement overcoming the force of gravity).

II. Push-off phase.

Plantar flexion at the ankle joint. Driven by the plantar foot muscles, as well as the posterior and lateral muscles of the lower leg.

Extension at the knee joint. Driven by the quadriceps femoris.

Extension at the hip joint — executed by the gluteus maximus and minimus.

Spinal extension (posterior back muscles).

Flexion of the forearm and extension of the arm at the shoulder.

III. Flight phase.

Body tuck and rotation around the transverse axis. The legs flex at the hip joints (anterior thigh and pelvic muscles) and knee joints, the foot extends (anterior compartment muscles of the lower leg), the arms lower (muscles of the pectoral girdle), and the head tilts backward (posterior Neck Muscles).

The tuck decreases the moment of inertia and increases the angular velocity of rotation. At the end of the 3rd phase, the movements are reversed to reduce the rotational speed. Body straightening begins near the end of this phase.

IV. Landing.

The lower limbs are partially flexed for shock absorption (flexor muscles perform yielding work). The torso and upper limbs do not fully extend. This is necessary for body balancing, ensuring that the trajectory of the center of mass passes through the base of support upon landing.

Somersaults are easier to perform for shorter athletes due to their smaller moment of inertia.

Respiration: inhalation during the push-off (raising the arms), exhalation upon landing.

Promotes the development of jumping ability and coordination.

Self-Assessment Questions:

1. Characterize the MAIN TYPES OF upper limb movements.

2. How do various body positions and movements affect internal organs?

3. What are the distinct Phases of the long jump?

Changes in the body during physical activity

Depends on the period of human life.

During ontogenesis, a person goes through 3 stages:

1. evolutionary stage — structural formation prevails, accompanied by GROWTH AND DEVELOPMENT up to the size of a mature Organism;

2. stable stage — a balance between formation and degradation processes in the mature organism, with weight changes occurring mainly through adipose tissue;

3. involutionary stage — degradation processes prevail, leading to Aging of the organism, along with a decrease in body mass and dimensions.

Biological age is determined by the condition of organs and systems, and it may not coincide with chronological age. Motor age is also distinguished based on physical activity. Engaging in physical exercises helps maintain motor age largely unchanged for a long time, thereby delaying the aging process of the body.

The Scope of movement is typically measured by the number of steps—the pedometry method. A specific number of steps is required for each age group. For example, adolescents need 20,000 to 30,000 steps per day.

Physical activity triggers an adaptive response across the entire body.

Low-intensity loads have virtually no effect on the body. Moderate-intensity loads stimulate morphological and functional restructuring within the body. High loads inhibit these processes, while excessively high loads cause Functional and Structural impairments. The body's susceptibility to physical loads is individual and referred to as the norm of reaction.

Adaptation to Physical Load

The Mechanism of adaptation is the stress response, which unfolds in three phases:

1. Alarm phase: intensive workloads induce shifts in Homeostasis; in response, the Adrenal Glands secrete increased amounts of adrenaline, which exerts a vasoconstrictive effect.

2. Resistance phase: adrenal corticosteroids are released, providing protective and anti-inflammatory effects while stimulating growth. Prolonged and intense exposure leads to

3. Exhaustion phase: depletion of the adrenal glands occurs.

Body adaptation ensures that physical activity eventually ceases to trigger a stress response.

Pathways of Adaptation

During the evolutionary phase of ontogenesis, adaptation is driven by growth processes. Physical loads induce changes in the skeletal, endocrine, and nervous systems.

In the stable phase, growth is complete, and compensatory-adaptive processes take place.

In the involutionary phase, Physical Exercise helps regulate aging processes.

Managing Adaptation

The norm of reaction can be enhanced through specific and non-specific means.

Specific means: low- and moderate-intensity mechanical loads.

Non-specific means: preliminary exposure to high-altitude conditions (Hypoxia factor), and chemical agents that stimulate Biosynthesis (such as orotic acid or purine bases).

AGE AND SEX factors must also be taken into account. The older the age, the lower the recommended load; women generally have a higher norm of reaction, yet at the exact same chronological age, biological age can vary significantly. For instance, 14- to 15-year-old boys easily tolerate increased physical exertion, whereas it may have adverse effects on girls, potentially impairing reproductive function. Body constitution is another factor: the norm of reaction is lower in hypersthenics and higher in asthenics.

Self-Assessment Questions:

1. What bodily changes occur during the evolutionary stage of ontogenesis?

2. How can adaptation be managed?

3. What is meant by the "norm of reaction"?