// Deep In the Core: Core training in deep water

by Irene McCormick

Deep water exercise remains a popular and viable alternative to land-based modes of fitness training. The numerous benefits include a non-impact, suspended, comfortable working environment, as well as a variety of intensity options and full range of motion. A properly designed deep water workout incorporates most of the components of a typical landbased workout, resulting in measurable fitness gains and the attainment of health and wellness goals. This article will seek to highlight the properties of water exercise. Additionally, it will target techniques that, when used effectively, can increase core strength in deep water and can be considered an effective and enjoyable alternative to land-based core training.

Buoyancy versus Gravity

Water fitness is often undervalued as an effective training stimulus for performance enhancement based on a common perception that it is a comfortable and easy form of exercise.

To the contrary, deep water workout training transforms this perception into one of a dynamic and intense core fitness regimen. A key component of deep water is the concept of buoyancy.

The use of water as a training medium requires manipulating buoyancy, a factor that opposes gravity. The Archimedes Principle defines buoyancy as ‘any object that is wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid

Deep in the core

Core training in deep water displaced by the object’. In other words, a direct relationship exists between the weight of the submerged part of the body and the amount of fluid displaced.

Additionally, the effects of buoyancy are increased as the lungs become submerged. This is a concept that is not well understood by land-based fitness professionals, but one that most water fitness professionals understand and benefit from.

Participants in deep water who have a lower percentage of body fat have a tendency to be less buoyant and have a greater likelihood of sinking. Conversely, participants with a higher percentage of body fat will be more buoyant and are more likely to float.

Participants with either body-type who also have limited core strength will have a propensity to ‘turn and roll’ until their body finds a place of equilibrium when exercising in a deep water environment. The neurological processes must find the new pathways for the successful completion of this new task of maintaining an upright posture.

The basic exercise science principles apply in deep water, but because the environment is so different from land and shallow-water, the training methods used to create effective exercises are unique to the suspended environment.

All core, all the time The diminished effect of gravity plays a crucial role in demanding that each participant strives to achieve optimal posture and spinal alignment in deep water. Buoyancy, and the necessity to constantly balance and stabilise the body, results in the core muscles working at a higher intensity and at a constant rate. When the weight of the submerged body is equal to the weight of the fluid displaced, the body’s centre of gravity (the hips) and the body’s centre of buoyancy (the chest/lungs) will be in vertical alignment. However, if this equation is not equal, the participants will struggle to stay upright and vertical in the water.

Since participants are not anchored to the pool bottom, as they are in shallow-water or during land-based programming, buoyancy creates an inherently unstable working environment and deep water exercisers experience tremendous challenge to the muscles that support the spine.

Exercisers must engage the stabilising muscles of the core more aggressively to maintain vertical alignment and proper body positioning. Effective core training can be achieved through deep water exercise design that promotes a balance of both the physical properties of water and the unique dynamics of the buoyant environment.

Exercise selection in deep water

During deep water exercise, both safety and exercise effectiveness are increased when the centre of gravitational balance is aligned with the centre of buoyancy. Humans are bipedal and the erect stance is fundamental to healthy function. Deep water exercisers must learn how to balance between these two points for successful training results to occur. Since there is no stable base of support in deep water, the abdominals have to work to maintain a ‘land-like’ upright posture, constantly firing the muscles of the core.

In deep water, fluid dynamics are exaggerated, so a movement in deep water causes a more pronounced reaction, therefore balance is critical. Jogging or cross country ski exercises are easier to perform in the deep because both sides of the body match in their sagittal plane motions due to the symmetrical movements. Although effective at stimulating the core muscles, those who wish to take advantage of core training opportunities in the water should perform asymmetrical exercises. Asymmetrical movements are much more challenging because the uneven movements of the legs and arms cause the torso to shift away from a vertical, upright posture. As the participant feels the body going off-balance, an attempt to maintain a vertical working position is made. This forces the muscles of the trunk to work harder. This is what encourages excessive core muscle recruitment.

Exercise examples that recruit core muscles

Examples of exercises that are appropriate for recruiting the muscles of the core in deep water include:

• Mogul jumps.
• Single-leg jacks.
• Knee lifts.
• Inner thigh lift/ankle reach in front.
• Backward jog.
• Biking.
• Vertical flutter kicks.
• Leg curl/hamstring curl.
• Front kick/karate kick.

Equipment options

Equipment can add variety, alter workout intensity and allow for exercise progression. Buoyancy equipment is especially important for deep water exercise.

Equipment that floats allows the participant to work in a suspended position. A flotation device or other buoyancy aid is necessary in deep water to promote a participant’s safety and comfort. While it is true that people with swimming skills can stay afloat, few can sustain a vertical posture in deep water without experiencing eventual fatigue. Without added flotation, a large amount of energy must be expended to keep the head above water and this may put your participants into ‘survival mode’ just to stay upright. Equipment such as buoyancy belts, dumbbells, ankle cuffs, noodles and other flotation devices are recommended. This equipment will assist with buoyancy to support and enhance upright posture as well as provide for optimal range of motion. Buoyancy equipment can also add to the resistance experienced by the participant.

Potential issues with buoyancy equipment

Equipment that excessively promotes buoyancy will make it difficult for exercisers to maintain their centre of balance, disallowing them to master control of their movements.

Difficulty pushing with force through the water is also likely to result. A loss of biomechanical balance is often the result of the participant using the same movements over and over again simply to stay afloat. On the other hand, too little buoyancy affects the participant’s ability to maintain a vertical position in the water.

Take care with the placement and positioning of buoyancy equipment on the body. A well-fitting buoyancy belt will allow an individual to maintain proper vertical alignment with the head held comfortably above the water when in a motionless position (AEA Manual, 2006). With proper flotation, participants can focus their energy and efforts on full range of motion movements that employ all the major muscles in all planes of movement.

Performance errors and suggested corrections

The most common performance error in deep water exercise is poor body alignment. Another common error is a marked lack of coordination and inability to maintain balance.

Individuals who are unskilled and/or unfamiliar with deep water exercise often lean forward at the waist in an effort to compensate for the dynamic change in their centre of balance. This posture makes deep water exercise easier to perform, but it inhibits the proper muscles from doing the work. By maintaining an upright, vertical and aligned posture, participants enhance frontal resistance, core muscle recruitment and exercise intensity.

The unique properties of the deep water environment require thought and scientific logic on the part of the instructor when developing safe and effective deep water programming. Producing positive training results from understanding the various ways in which the buoyant environment affects human movement and the body’s response to exercise. This knowledge can prepare an instructor to develop deep water teaching skills and lead clients through effective deep water exercise selections that will be well worth the effort.


Irene McCormick, MSc, CSCS
An AEA certified instructor, Irene is a veteran fitness presenter, published author, personal trainer and fitness expert for the American Council on Exercise (ACE). She has created two certification courses and featured in seven DVDs. Irene is also an editorial board member and regular fitness contributor to Diabetic Living and Heart Healthy magazines. For more information e-mail irene@irenemccormick.com or visit www.irenemccormick.com


NETWORK • SUMMER 2009 • PP60-61