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Strength Training in the Pool

Is it even possible? And if it is, how can you accomplish it?

Guest Blogger: Irene Pluim Mentz

Most of you reading this have background in water exercise, but just to recap a few of the most basic hydro-dynamic principles:

  • Water molecules like to stick together, known has cohesion, so when something gets moved through water it takes force to “break apart” that cohesion.

  • Once an object is moving, whether it be in air or through liquid, it needs a force applied against it to either change direction or speed, better known as the Law of Inertia.

  • Smaller, narrower objects displace fewer water molecules, requiring less force; larger, wider objects moving through water break up more water molecules, hence requesting a greater output of power. This principle is referred to as “drag.”

Force = Power = Strength

Now let’s talk about drag resistance a little bit more. If you have exercised in water before, you know about drag resistance. Some call it frontal area resistance, depending on what movement you perform in water. In water, it is possible to increase drag, and thus the need for increased force, in all three planes of movement; i.e. frontal, sagittal, and transverse.

With land exercise, there is always the gravitational force to overcome. When you are swimming horizontally, you want to be as streamlined as possible in the water, therefore minimizing resistance and increasing the ability to last longer. However, for training, many swimmers will wear “drag suits;” i.e. trunks with pockets or loose fitting suits, even parachute-type equipment attached to their bodies. Even runners and bikers use the principle of drag in their training and will do whatever they can to minimize it during races.

So when you exercise in water, you can utilize drag and frontal area to your benefit; especially given the cohesive nature of water molecules. When you just are just beginning with your work-out program, you want to have minimal resistance. You can obtain this by keeping your surface area and movements slow and small, working on improving coordination, balance, and movement patterns. But then you can start increasing your work load by adding more speed and /or moving larger surfaces through the water.

More speed created in water might cause turbulence. Let’s illustrate this:

Imagine yourself looking at water flowing through a river: you will see regions were it flows calmly, called a laminar flow. But then there are some rocks obstructing the water’s flow and the water will be foamy and there might be some eddies; there the flow of water is called turbulent flow.

Now see yourself standing in this river; first you are in the calm flowing, laminar flow of it: you feel some resistance but nothing you can’t withstand. So you move toward the rocks with the foamy, turbulent water and you barely can maintain your balance! The drag force created by the laminar flow is proportional to its velocity, while the drag force of the turbulent flow is squared to the velocity.

The next moment you have an oar in your hand, and the turbulent flow almost rips that out of your grip and you have to apply more force to maintain hold of it and you actually lost your balance; while it was easy to hold on to that oar in the calmer flowing water where you could quietly stand.

Similarly, you can use equipment increase surface area in your water exercise programs. Characteristics of this type of equipment include that they enlarge the surface area.

One of the options for this type of equipment is the Aqua-Ω (pronounced: Aqua-Ohm).

The Aqua-Ω is purposefully slightly negatively buoyant, to enable optimal utilization of the three-dimensional resistance of the water molecules’ cohesion. When using bouyant drag resistance equipment, the force requested becomes two-dimensional, since that equipment would always want to rise to the surface.

Invented and developed by a physical therapist, the patented Aqua-Ω is an exciting piece of fully adjustable drag resistance water exercise equipment which can be used to increase surface areas for both arms and legs. It can be adjusted for size and resistance level to accommodate everybody, and since it is not buoyant, it is easy and safe to use for all populations and purposes. The Aqua-Ω is fun to use in both deep and shallow water as well as for boot camp style classes and arthritis management. An extra benefit of the Aqua-Ohm: It packs small and travels well while it is affordable.

Just visit our website at or email us at for more information.

To recap: YES, you can perform strength training in the pool! All you have to do is increase your speed and/or your surface area.

An increase of needed FORCE = Increased POWER = Increased STRENGTH!


Irene Pluim Mentz, PT became a licensed physical therapist in the Netherlands before immigrating to the United States. She is the co-owner of One Step Beyond, Inc. Physical Therapy. Irene’s passion for anything “water” led to becoming an AEA certified instructor. She integrates her knowledge of hydro-dynamics with physical therapy into all her sessions. Irene is the inventor and developer of the Aqua-Ω adjustable drag resistance water exercise equipment.

Contact Irene:



Join us April 28-30th in Seattle, WA for the 2022 PNWFITCON!

In addition to several other workshops, Katy will be demonstrating the true versatility of the Aqua Ohm device as part of her session AQUAFIIT: Power of Ω!




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