This presentation focuses on the technological approach related to the evaluation of muscle strength and power.

1. TECHNOLOGY IN THE
EVALUATION OF
MUSCLE STRENGTH
AND POWER

2. This presentation focuses on the technological
approach related to the evaluation of muscle strength
and power

3. Obtaining the muscle power curve for strength training
programs
Power training typically involves exercises which apply the maximum amount of force
as fast as possible; on the basis that strength + speed = power.
Maximum power is the greatest result stemming from this relationship.
This value is highly important within training, and its calculation will allow us to orient
strength training, always referring to maximum effort, towards hypertrophy (left of the
force-velocity curve) or towards speed (right of the force-velocity curve).

5. Once the load has been established in accordance with the training program, we
must control the execution power in order to determine if we have effectively
executed the desired manifestation.
This can be achieved by using a linear encoder (to evaluate gravitational loads) or
a rotary encoder (for inertial loads).

6. Linear and rotary encoders
Linear encoder
● Cable: 3 meters length.
● Suitable for any exercise, but
connect to inertial machines is not
recommended.
Rotary friction encoder
● Connect to any rotating or sliding
machine.
● Easy to fix to any place.
● Sizes of rotary friction encoder.
Rotary axis encoder
● This encoder has to be adapted by
a manufacturer
● This encoder should be fixed to
machine axis
● Sizes of rotary axis encoder

7. Linear encoder photos

8. Linear encoder photos

9. Rotary encoder photos

10. Rotary encoder photos

11. Controlling power by means of encoders
Simply put, an encoder is a sensing device that provides feedback.
Encoders convert motion to an electrical signal that can be read by some type of
control device in a motion control system.
The encoder sends a feedback signal that can be used to determine position,
count, speed, or direction.
As I wrote earlier, there are two types of encoders: linear encoder (to evaluate
gravitational loads) or a rotary encoder (for inertial loads).

12. Encoder tests

13. Encoder capture graph

14. Asymmetries in functional tests
There have been an increasing number of studies in the past decade on
asymmetries in neuromuscular skills, such as change of direction, jumps and
sprints at maximum speed.
In addition, the differences observed between two body parts may or may not be
related to different aspects of performance.
Keeley et al. propose that “Asymmetrical strength across the lower extremities can
be defined as the inability to produce a force of contraction that is equal..”
Asymmetries have been reported as a percentage with distinctions being made
between dominant and nondominant, right and left, stronger and weaker, or
preferred and nonpreferred limbs.

15. Asymmetries in change of direction
We must bear in mind that this ability has traditionally been studied within a test
that also incorporates displacement speed (known as the CODS test).
The data related to asymmetries in the CODS tests reveal very low values in the
different studies conducted.
Another essential element of the studies related to asymmetries is the relationship
that these might have with different aspects of sports performance.
In this regard, we should note that asymmetries depend on the type of test
performed.

16. Studies on
asymmetries

17. Integrated systems in muscle evaluation
When we refer to biomechanical studies in relation to sports, we usually refer to the
incorporation of kinematic, dynamic and electromyographic signals.
In terms of the devices used, a video camera system is usually incorporated to
provide the total kinematic data of an action, along with a force platform to directly
study these characteristics, and an electromyography with the aim of observing the
sequencing and simultaneity of the activation of the different muscles being
studied.

19. Force platforms and kinematic study
Force platforms or force plates are measuring instruments that
measure the ground reaction forces generated by a body standing
on or moving across them, to quantify balance, gait and other
parameters of biomechanics. Most common areas of application
are medicine and sports.
The force plate is capable of measuring reaction forces in all
three dimensions: the vertical (z axis), the horizontal (y axis), and
the transverse direction (x axis).
Kinematics is a branch of classical mechanics that describes the
motion of points, bodies (objects), and systems of bodies (groups
of objects) without considering the forces that cause them to move.

20. TECHNOLOGY IN THE
EVALUATION OF
MUSCLE STRENGTH
AND POWER