Water Resistance - What is it study series?

WATER RESISTANCE

Water has approximately 12 times the resistance of air. This aids muscular strength and endurance and can increase intensity for the exerciser; however it also slows their movement down.

Resistance occurs from the viscosity of the water, water is more viscous than air. When the viscosity is high the flow of fluid is slower and resistance is higher. Viscosity of water generally decreases as temperature increases.

In water there are 4 types of resistance; Surface tension, Frontal resistance, Eddy drag and Viscous drag

Surface tension

  • The surface tension of water offers a greater resistance as it is more viscous.

  • Moves that break the surface tension may be more difficult.

  • So raising the arms above the surface and then breaking back down can raise the intensity of that move.

Frontal Resistance

  • There is more frontal resistance in water than sideways as there is more mass meeting it head on. There is more resistance when the hand hits the water flat on than sideways on.

  • It is 3x harder to move in water

  • Increased intensity of all moves

  • Larger surface area and increased speed lead to greater intensity

  • Decreased movement speed

  • Dual concentric muscle contractions

Drag Forces

Drag forces are always present when moving through water

Eddy drag

  • As the limb moves small eddy’s of currents are created alongside of it.

  • These whirlpools increase along with resistance if the limb is slightly bent.

  • Decreases the ability to change direction quickly

  • Sculling uses this resistance

Viscous Drag

  • Viscosity = ability to pour

  • Warm water is less viscous than cold water therefore easier to travel through

  • Skin friction = caused by resistance of water immediately next to the body. Water sticks to body and adds to resistance.

  • Tail suction = water not being able to fill in behind the poorly streamlined body so the body pulls along a certain amount of water from behind. Formed behind the body. Participants can cheat by travelling behind someone!

Streamlined or Turbulent water movement

Water resistance due to turbulent flow is greater than that due to streamlined flow. Pressure builds in front of an object and decreases behind it as it moves through water; this creates a wake behind which water flows into. Eddy’s can form in the wake and this tends to draw the object back. The faster the movement the greater the drag back.

When a group is working together, more drag and turbulence can be created so those on the outside may have to work harder. Consider changing the group’s position frequently to even it out e.g. Circles, lines, and change of class front. Also think about your weaker class participants and put them away from the edge of group.

MOVEMENT SPEED

Moving through water with ballistic land based movements can cause injuries to joints and ligaments.

Movement should be slowed down to allow full range movement without jerking or compromising alignment.

Movements should always be controlled, i.e. jogs and kicks would be slower in the water than on land.


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