El Deber Constitucional de Protección Animal a partir de la “Constitución Ecológica” de

In this section I develop a theoretical model of the performance of kayakers with spinal cord injury (see section 3.2.12), to develop a better understanding of the problem to be solved, as well as to better understand the relationship between

the athlete’s performance and the equipment. Literature searches reveal little on the study of athletes with SCI participating in kayaking.

There is also little data concerning the postural mechanics of non-disabled kayak athletes. There is data on the action of core stability on the performance of non- disabled kayak athletes. I therefore consider this to create a base-line for the generation of a model of kayaking for non disabled athletes before then utilizing it as a baseline for the assessment of kayakers with SCI.

I consider the nature of the performer in terms of what is good posture and stability and how components of standard equipment resolve the forces within the kayaking system.

When considered in a rehabilitation context, stability is reported to be essential for performance of daily living tasks. According to Aissaoui et al (2001 p.274):

‘Dynamic sitting refers to the continuous process of postural changes during sitting. Sitting posture is usually unstable without additional external support because the hip joints are in an intermediate position with respect to the range of motion and because the trunk cannot be locked relative to the thighs by ligamentous restraint. As a result, muscle activity is necessary to maintain the trunk segment in an upright posture when sitting without additional stabilizers. The capacity to maintain balance and posture in sitting is a prerequisite to the activities of daily living (ADLs), and deficits in sitting balance control can severely limit task performance.’

Stability therefore provides the nexus for: kayaking posture, SCI posture and elements of the mechanical model of kayaking, described previously as power circles. There is also a link between stability and optimal performance; creating

stability for the performer must be a key performance indicator for the success of any design solution in this research. Elphinston (2005) defines stability in a paddlesport context as the ability of the body to withstand, support and generate forces with optimal efficiency and minimal musculoskeletal stress.

Elphinston (2005) goes on to suggest the likely ways in which failure in any of the power circles can affect performance. The role of equipment in supporting good posture is considered later in this chapter. Table 16 provides a start-point for understanding the nexus between task (or sport), performer, and equipment.

Table 16 Power Circles and Core Stability – Presented from the base up.

Power Circle

(No. 1)

Name/

Description

The Basement of the Stroke – Leg and buttocks

Key

Principles

Forward paddling built on support by the water

Body connected to the water by the feet/ footrest and the bottom of the seat.

Firm connection between with the hip as the foot presses on the footrest.

Provision of a firm base for stroke.

Technical Perspective

A weak leg drive means a loss of connection between the

footrest, the hip/seat, the boat and the water. There is no base to build the paddling upon.

Physical Perspective

The legs should push the pelvis into rotation. Two elements are necessary.

The pelvis must have the mobility to rotate

The muscles which connect the thigh and the pelvis by crossing the hip must secure the joint so that the force of the leg is

transferred effectively to the trunk. Good functioning of the gluteus maximus and gluteus medius is essential.

Power Circle

(No. 2)

Name/

Description

Body Rotation – The trunk rotates.

Key

Principles

Whole body, the trunk rotates on the firm base provided by the legs and the pelvis.

Whole structure rotates as one, keeping an upright posture.

Arms connect the trunk to the paddles but do not work independently.

Connection between shoulders and the paddle blade, from shoulder to shoulder.

Technical Perspective

The Upper body structure breaks up, arms bend, the shoulder/trunk area cannot hang onto the catch. Push/pull paddling is often the result.

Physical Perspective

To maintain power circle 2, several elements are necessary.

A strong neutral trunk position. If the trunk is collapsed, it pushes the shoulder girdle forward and upwards. This makes it impossible to use the shoulder stabilizers effectively.

A stable upper zone. This upper zone is the shoulder girdle, and lower trapezius and serratus anterior are the main muscles involved in stability of your shoulder blade. The shoulder blade (scapula) must be stable to transfer forces from the arm to the trunk. Trunk rotation. If there is insufficient trunk rotation, the force from the arms has nowhere to go.

Equipment Perspective

Integrity of the paddle shaft, and upper girdle of the performer.

Power circle 3 (muscles of the trunk) forming the base of support.

Power Circle

(No 3)

Name/

Description

The Catch –

The lower arm is straightened and the paddle is driven down into the water in front of the cockpit using the power of the whole connected trunk.

Key

Principles

Paddle becomes fixed in the water to move the boat past.

Technical Perspective

The shoulder arm connection is not secure, the catch cannot be locked, the paddler is not able to hold connection between blade, shoulder, hip and footrest.

Physical Perspective

A combination of upper and lower body elements may be at fault.

Equipment Perspective

Back rest, foot rest, trunk, arms and paddle shaft.

Power Circle

(No.4)

Name/

Description

Move the Boat Past the Blade – The blade is locked at the catch and the opposite hip drives the boat forward as the trunk unwinds powerfully against this fixed point.

Key

Principles

Slide boat past paddle.

Connection with blade in water and opposite hip.

Hip blade connection maintained throughout the stroke.

Technical Perspective

The paddler cannot apply the power and move the boat as there is a breakdown in the connection between the blade and the opposite hip.

The boat rocks away from the catch.

Physical Perspective

To prevent this problem, the paddler must have a secure trunk. If it is collapsed into a slump, it will be difficult to stabilise the pelvis in a side to side direction (the coronal plane).

If they cannot rotate their pelvis, their movement will be shifted into the alternative plane of movement allowed by sideways collapse of the pelvis.

Equipment Perspective

Trunk muscles supported by the basement of the stroke (3).

Power Circle

(No. 5)

Name/

Description

Top Arm Connection – The top arm is pushed forward and the trunk rotates but remains connected to the movement of the trunk structure.

Key

Principles

Connection between the stroke side foot and the opposite (top) hand, compressing the paddle shaft.

Keep top arm as part of trunk structure.

Technical Perspective

The Top arm becomes disconnected from the whole body structure and flies upwards out of control. The trunk wriggles and connection is lost between boat and upper body.

Shoulder, balance and trunk control problems could contribute to this.

Physical Perspective

As 1 rotation will involve 4.

Equipment Perspective

As 1 rotation will involve 4.

Table 16 identifies the equipment elements and physical elements that need to be considered. The key equipment elements are; foot rest, under deck, thigh braces, seat, backrest and paddle. The physical elements are; legs, pelvis and trunk, and upper girdle. The most complex rotational forces are those involving trunk rotation, which directly demand core stability. I therefore propose to look

at core stability in more detail before moving on to look at the equipment implications.