Continuing our study series with the aerobic and MSE components of a class and how to use the properties of the water.
The aim of the aerobic component is to provide exercises that challenge the cardiovascular system by requiring large amounts of oxygen to be delivered to the working muscles. As with other forms of activities the exercises need to be sustained at an appropriate intensity and for a sufficient duration of time to produce a cardiovascular training effect.
The effects of water on the structure and content of the aerobic component:
Heart Rates and Heart Rate Monitoring
It is well known that in order to exercise the cardiovascular system effectively, the heart rate has to be elevated into the individual’s training zone by performing exercises that use the large muscle groups of the body.
However resting heart rates are reduced when immersed in water, but by how much is dependent on pool temperature (cooler pool = lower heart rate) temperature of the atmosphere and the depth of immersion (buoyancy and hydrostatic pressure increase in deeper water, which contributes to improved circulation and thus reduces the heart rate).
One study in America showed a significant increase in exercising heart rate when subjects exercised in waist-deep water as opposed to chest-deep water (however, this factor has to be weighed against the advantages of exercising in chest-deep water, with the greatest benefit being the reduction of gravitational forces which decreases stress on the weight-bearing joints).
Ultimately the estimation of target heart rate and oxygen uptake during water-based exercise requires more scientific investigation and until more is known about the effects of water on heart rate, other measures should be adopted to monitor exercise intensity. (Talk test etc).
Buoyancy is increased when the body is immersed in water and as has already been stated, heart rates will consequently be lower. This is because the water provides greater support to the body (floatation) and thus the muscles of the leg do not have to work as hard as they would in land-based exercise programmes (non weight bearing due to the effects of gravity).
Deeper water provides a greater support and thus heart rates tend to be lower than in shallow water. Thus to achieve a training effect, the intensity of the exercise needs to be significant and the intensity of the second pulse raiser and pulse lowering activity may need to increase/decrease more rapidly.
However when immersed at chest depth, the gravitational forces are reduced by approximately 80% and thus it is very effective and much less stressful to include a higher proportion of large jumping and hopping activities (traditionally of higher impact on land) within non-specialised aqua programmed to promote an effective workout.
Due to the resistance provided by the water it takes approximately three times more energy to walk in water at the same speed as walking on land. Thus, movements will generally need to be slower as fast-paces movements would become extremely fatiguing and potentially be less effective due to the decreased effort from participants. It is therefore advisable to use a variety of rhythms and combine slower moves (which utilise a fuller range of movement) with short bursts of faster paced moves in order to create the desired overload on the cardio-vascular system.
In addition the joints of the upper limbs are more flexible/mobile and when used through a full range of movement against the resistance of the water (underneath the surface) can require greater effort from the larger muscles of the back and chest. Thus if these are combined with traditionally low impact leg movements, this can be very effective in achieving the required target heart rates.
The resistance (especially eddy currents and turbulence) may also make it harder to change direction quickly and this therefore requires a higher number of repetitions to be performed for a specific muscle area. Whilst this will improve muscular endurance (and within a broader range of muscles than on land e.g. arms and back) care should be taken to vary joint actions so as not to create fatigue of one area (imbalance).
The combined effects of the properties of water enable the second pulse raiser (build up aerobics) and pulse lowering activity (cool down aerobics) to be shorter and of a comparatively steeper incline/decline of intensity (respectively).
However, this is also determined by the fitness and needs of the class participants. Therefore:
A higher proportion of high impact and power moves can be utilised due to the decreased stress on joints (buoyancy)
Upper body work/arm exercises are more effective than on land (due to the increase in resistance if the arms are kept under the water)
A combination of slower, larger, full range movements with short bursts of smaller, slightly fast moves to increase intensity can be utilised
More time is needed for directional changes and thus higher repetitions of each exercise will be more effective.
Muscular Strength and Endurance Component
The aim of the muscular strength and endurance component is to provide exercises that “overload” specific muscle groups in order to bring about the desired training effect.
As with other exercise programmes it is essential that muscles selected for work are those that need strengthening to improve muscle balance, promote correct posture and which will assist with daily activities. Therefore it is advisable to prioritise the muscle groups selected and perhaps target those which have had less work throughout the aerobic component to achieve the desired ‘whole body approach’.
The effects of the properties of water on the structure and content of the muscular strength and endurance component:
The feeling of weightlessness experienced by the body when immersed in water requires that the majority of movement be brought about by concentric muscle contractions.
Eccentric muscle contractions are virtually eliminated because the water offers a constant resistance to all movements.
Delayed onset muscle soreness (DOMS) should be reduced as it is eccentric muscle work which is a primary cause of this. However, the use of floatation equipment, e.g. water bells, floats and tubes will increase buoyancy and therefore require some eccentric muscle work.
The buoyancy and floatation properties of water will provide support to some static exercise positions and thus reduce the fixator work required by some other muscle groups. However when other limbs start to move, the body will move in the opposite direction (action/reaction – propulsion) and therefore other muscles will need to work hard as “fixators” to adopt a static position – especially the abdominals in order to protect the back.
In order to reduce some of the fixator work it is advisable to use a variety of starting positions such as freestanding, poolside and possibly floating positions using buoyancy aids.
A more stable base can be assumed in waist-depth water for lower body work but the upper body will chill quickly.
Transitions between exercises need to be planned in order to ensure that there is minimal hesitation when moving from one exercise to another and to promote effective flow of the component.
Propulsive movements of the arm can be used during leg exercises (and vice versa) to maintain balance. However it is essential that participants are advised where the emphasis of resistance should be placed. It is not realistic to expect maximal resistance work in both areas simultaneously.
It is essential for teachers to explain and demonstrate the correct starting position prior to commencing the exercise and to offer alternative stances/pool grips based on individual needs.
In addition teachers should recognise that the floatation provided by the water makes it easier to cheat the exercise by letting the water do the work and thus participants need to work hard to maximise the resistance against each movement.
The constant resistance provided by the water to the performance of all movements, whatever their direction, requires the majority of joint actions to be brought about by concentric muscle contractions. Additionally this constant resistance facilitates isokinetic type training. (In isokinetic contractions, the muscle contracts and shortens at constant speed. An isotonic contraction is different to an isokinetic contraction because it is usually slowest at the start.)
The greatest benefit of the resistance provided by the water is that a greater range of upper body exercises can be effectively included within the MSE component. Therefore, the upper body should be kept underwater to maximise the use of this resistance. For most participants, the constant opposition to movement provided by the water will not provide “maximal” resistance and hence most gains will be towards the endurance end of the continuum. However by increasing the speed of the movement, the range of motion and/or the surface area, then greater muscular output will be required which may bias the exercise towards the strength end of the continuum. Particular attention should be paid to the position of the feet and hands to ensure that appropriate resistance is offered to each exercise.
The use of floatation equipment e.g. floats or water bells will also increase the resistance (and potentially promote strength biased gains) by providing a greater surface area and increasing the buoyancy of the lever to which they are attached, as well as adding variety to the session.
Teachers should recognise that in many instances equipment may not be available and without equipment they would be advised to combine slower movements, which utilised a full range of movement, with short bursts of faster movements which if performed correctly will increase intensity.
It is not realistic to expect participants to work for very long at fast pace as it can be extremely hard work and fatigue may cause movements to become half hearted and therefore ineffective.
It is advisable to design routines to incorporate several sets of exercises for each muscle group and allow adequate rest time between sets to enable muscles to recover and ensure that maximal effort is possible for each exercise.
The number of repetitions, resistance used, sets and rest time should be planned according to fitness level of the class participants and adapted to suit individuals, as necessary.
The cooling effects of water will make it necessary to combine specific muscular strength/endurance exercises with other more energetic movements to maintain a comfortable body temperature.
In addition, if working in shallower depths or using the poolside to assist with balance, the non- moving or non- immersed body parts will cool quicker. It is therefore advisable to alternate the body parts which are worked as well as alternating partly-immersed with fully immersed positions.
It may also be beneficial to split the exercises, which make up this component and perform some of them before the aerobic component and some after, which is more effective in maintaining body temperature in cooler pools.
Provide sets/reps/resistance appropriate to the needs of the group, to establish “overload”
Combine muscular strength and endurance exercises with pulse raising moves to maintain body temperature
Prioritise muscles to achieve a whole body approach
A greater variety of upper body exercises can be included (resistance)
Predominantly dual concentric muscle contractions (buoyancy, resistance)
Isokinetic type training
Starting positions will be different (buoyancy)