Functional training of the respiratory muscles

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Chapter 7

Functional training of the respiratory muscles

THE RATIONALE FOR FUNCTIONAL TRAINING

As was discussed in Chapter 3 (section ‘Non-respiratory functions of the respiratory muscles’), the role of the respiratory muscles extends far beyond that of driving the respiratory pump. This fact explains why most, if not all patients, find walking makes them more breathless than riding a stationary cycle ergometer. However, the contribution of the respiratory muscles to postural control (balance) and core stabilization is not addressed directly in a rehabilitation context. This is surprising because these non-respiratory roles have profound implications for how we should train these muscles to optimize their function and minimize the unpleasant symptoms that they generate. A detailed description of the trunk musculature and its non-respiratory roles can be found in Chapter 3. The current section will focus upon the specific rationale for functional training of the respiratory muscles.

The non-respiratory roles of the respiratory muscles are often brought into conflict with their role in breathing; the external manifestation of this conflict is dyspnoea that is disproportionate to the ventilatory demand of the activity. Similarly, in patients with abnormal respiratory mechanics, muscles that do not normally make a substantive contribution to breathing can become vital contributors to thoracic expansion. This helps to explain why patients become breathless during activities of daily living that engender only modest increases in ventilatory demand, such as dressing and hair washing.

Because of the multiple roles of the trunk muscles, respiratory muscle training cannot be optimized if it is delivered using an exclusively ‘isolationist’ model of training, i.e., if optimal function is to be achieved, the core stabilizing role of the diaphragm must be trained in the context of an activity that challenges core stability. Notwithstanding this, there remains a role for the isolated training of the ‘Foundation’ phase (see Ch. 6), which provides the foundation onto which functional training is built – in other words, an ‘isolate, then integrate’ approach to training.

The rationale for functional respiratory training is identical to the rationale for any kind of functional training. When functional conflicts occur within the muscular system, the risk of system failure can be mitigated by providing the muscles in question with reserve capacity (Foundation inspiratory muscle training: IMT), as well as by establishing specific neural activation patterns as routine through training (Functional IMT).

As was explained in Chapter 5, muscles respond to training in highly specific ways that limit the transferability of training benefits when the training stimulus is non-functional (e.g., an isolated leg extension is unlikely to improve walking performance). In functional training, muscles are subjected to forces during functional movements in order to develop the neuromuscular system in ways that are transferable to real-world activities. To date, a missing element from the functional training repertoire has been any consideration of the role of respiratory muscles (major trunk stabilizers and controllers) in functional movements, and vice versa.

As well as satisfying the demands of breathing, the trunk muscles are responsible for a wide range of movements during activities of daily living, e.g., flexion, extension, rotation, stabilization and so on. Ambulation involves continuous perturbation to postural control whilst simultaneously increasing the demand for breathing. These challenges are exacerbated still further if ambulation is combined with carrying, as the trunk must also be stabilized exerting a compressive influence on the thorax. The respiratory muscles must accommodate all of these functions simultaneously, a requirement that demands specific training.

Although it is commonplace to use functional training techniques in a clinical rehabilitation context, functional training movements are typically undertaken as brief, isolated exercises in which the ventilatory demand remains modest. Thus, these exercises rarely simulate the simultaneous challenge of elevated breathing and functional movement accurately; indeed, it is typical for therapists to seek actively to minimize conflicts between breathing and movement by coaching patients to synchronize breathing movements so that the actions of the inspiratory and expiratory muscles coincide with extension and flexion movements of the trunk. Unfortunately, whilst helpful, this synchronization is rarely achievable in everyday life, with the result that the patients may remain unable to deal with the conflicting requirements of breathing and movement.

In his book on low back disorders, Professor Stuart McGill rightly highlights the specific challenge that elevated ventilation represents to spine stability, as well as the increased risk that it poses for back injury (McGill, 2007). The therapeutic approach suggested by McGill is to undertake a range of stabilizing exercises (e.g., side bridge) immediately after an activity that raises ventilation, the idea being that the resultant hyperpnoea is superimposed on exercises that challenge the stabilizing musculature. The aim is to produce what McGill calls a ‘grooved’ pattern of muscle activation, similar to a rope running in a well-worn slot, so that breathing and stabilization take place simultaneously but without any compromise to either. Often, people cope with their inability to meet the conflicting demands on their respiratory muscles by holding their breath during exercises such as a side bridge. This is clearly a bad ‘groove’ to get stuck in.

The breathing challenge that is recommended in this chapter is not limited to raising ventilatory flow rate (as recommended by McGill); rather, the functional exercises that are recommended will also increase the requirement for inspiratory pressure (force) generation by the inspiratory muscles. These exercises involve breathing against an inspiratory load during functional movements. This is actually no different from using any external resistance during functional training (e.g., elastic resistance or dumbbell); its purpose is to challenge the neuromuscular system’s ability to bring about controlled movements.

In addition to providing a stable platform, the respiratory muscles play an important role in postural control during brief perturbations to balance. A good example of this is the automatic, anticipatory activation of specific trunk muscles immediately before large arm movements (see Ch. 3). The role of the diaphragm in this type of postural control is pre-programmed (‘grooved’); this is known because diaphragm activation precedes movements that destabilize the body (Hodges et al, 1997a; Hodges et al, 1997b). However, this automatic activation does not mean that the programme is not dynamic or adaptable; rather, the programme varies according to the movement parameters of the task and according to factors such as the prevailing postural conditions (stable or unstable), muscle fatigue, injury, pain and so on. For muscles that are involved in automatic anticipatory postural adjustments, such as the transversus abdominis, isolated specific training can normalize previously abnormal patterns of motor activation, i.e., restore a programme to normality (‘flip the rope back into the groove’) (Tsao & Hodges, 2008). In other words, isolated voluntary training of muscles involved in automatic anticipatory postural adjustments leads to improvement in complex automatic control strategies. The similarity of the diaphragm’s role to that of the transversus abdominis makes it extremely likely that this effect is also present for the diaphragm. Therefore, isolated voluntary training of the diaphragm (the kind of training undertaken during Foundation IMT) most likely enhances its automatic functioning during complex movements. The implications of this pre-programmed role of the diaphragm also need to be considered, and they are incorporated within the guidance on functional training provided below.

Finally, on a practical note, any close-fitting clothing (e.g., bras, waistbands, corsets) will restrict breathing by impeding inspiratory (outward) thoracic and abdominal movements. This needs to be considered in the context of functional training. Patients undertaking their training in loose-fitting exercise clothing will find the benefits diminished when wearing their normal clothing if this is tight fitting, and may be disheartened as a result. It is possible to simulate restrictions imposed by clothing, and this is also addressed in the guidance on functional training provided below.

ASSESSING PATIENT NEEDS

This section will suggest some methods for assessing patients in order to select the most appropriate types of exercise to meet their specific needs. However, by way of an introduction, patient assessment is placed in the context of what has typically been done to assess patients prior to implementing Foundation IMT.

Historically, patients being considered for Foundation IMT have typically been assessed on the basis of their inspiratory muscle function, and specifically their maximal inspiratory pressure (MIP) (see Ch. 6, sections ‘Patient selection’ and ‘Assessment of respiratory muscle function’). However, as was explained in Chapter 6, there are a number of reasons why MIP is not a good predictor of the likely benefits of Foundation IMT, and especially of Functional IMT. First, although reference values for MIP exist, the measurement is not straightforward to undertake, the equations have very poor predictive power (Enright et al, 1994; McConnell & Copestake, 1999) and the definition of ‘weakness’ is primarily statistical and not functional (Enright et al, 1994). Secondly, although patients with a MIP < 60 cmH₂O appear to show larger improvements than those with stronger inspiratory muscles (Lotters et al, 2002; Gosselink et al, 2011), those with stronger inspiratory muscles still show an improvement in breathlessness and exercise tolerance after IMT (Lotters et al, 2002). Thirdly, MIP takes no account of the demand side of the demand / capacity relationship of the inspiratory muscles; the closest functional correlates of dyspnoea are not indices of airway obstruction or gas exchange impairment, but rather inspiratory muscle function (O’Donnell et al, 1987; Killian & Jones, 1988) and the degree of lung hyperinflation (O’Donnell et al, 1998; Marin et al, 2001) – in other words, the relative load upon the inspiratory muscles. Finally, in the context of Functional IMT, MIP provides no insight into the conflicts that might exist between the respiratory and non-respiratory functions of the trunk muscles.

Accordingly, the use of functional, patient-centred indices would seem to be the most appropriate way to approach assessing the degree of functional overload of the inspiratory muscles, and thence the most appropriate approach to IMT. For severely incapacitated patients, Foundation IMT may be the most that can be achieved, but for those who are ambulatory, or have the potential to become so, functional training regimens can be developed. Since a functional approach has not been applied to date, there is no empirical evidence to guide the prescription of IMT based upon the demand / capacity imbalance principle. However, in order to ‘get the ball rolling’ in terms of generating functional, patient-centred indices of inspiratory muscle overload, one potential method is suggested below (see section ‘Assessment of load / capacity imbalance’). Prior to this, the assessment of dyspnoea is described briefly; as dyspnoea is not only the primary correlate of load / capacity imbalance, it is also relatively easy to assess.

Assessment of dyspnoea

Dyspnoea can be assessed in three main contexts: (1) by reflection upon the type of everyday tasks that elicit dyspnoea, (2) by quantifying the severity of dyspnoea during exercise using a rating scale, and (3) by quantifying the severity of dyspnoea during loaded breathing using a rating scale. Each has their own pros and cons, and the best ‘picture’ of a given patient’s limitations is probably obtained by using a combination of methods.

Reflexive assessment of dyspnoea

Of the many reflexive methods available, two of the most widely used and best supported by evidence are the Medical Research Council (MRC) Scale and the Baseline Dyspnoea Index (BDI) and Transition Dyspnoea Index (TDI) (BDI-TDI). Copies of these instruments can be found in Boxes 7.1 and 7.2A,B, respectively. These scales provide a useful insight into the limitations imposed upon everyday life by dyspnoea. In addition, the BDI-TDI allows changes to be monitored in response to interventions or disease progression.

Box 7.1 MRC scale

The original questionnaire contained over 60 questions (Fletcher et al, 1959), but an extract from the questionnaire has been used extensively over the past 50 years to assess the extent to which dyspnoea limits physical activity, i.e., the magnitude of the task that provokes dyspnoea. Patients select one from the following list of statements:

1. I get breathless only with strenuous exercise.

2. I get short of breath when hurrying on the level or up a slight hill.

3. I walk slower than people of the same age on the level because of breathlessness, or have to stop for breath when walking at my own pace on the level.

4. I stop for breath after walking 100 yards or after a few minutes on the level.

5. I am too breathless to leave the house.

Box 7.2A Baseline Dyspnoea index *

Functional impairment

Grade	Symptoms
4	No impairment. Able to carry out usual activities and occupation without shortness of breath.
3	Slight impairment. Distinct impairment in at least one activity but no activities completely. abandoned. Reduction, in activity at work or in usual activities, that seems slight or not clearly caused by shortness of breath.
2	Moderate impairment. Patient has changed jobs and / or has abandoned at least one usual activity due to shortness of breath.
1	Severe impairment. Patient unable to work and has given up most or all usual activities due to shortness of breath.
0	Very severe impairment. Unable to work and has given up most or all usual activities due to shortness of breath.
W	Amount uncertain. Patient is impaired due to shortness of breath, but amount cannot be specified. Details are not sufficient to allow impairment to be categorized.
X	Unknown. Information unavailable regarding impairment.
Y	Impaired for reasons other than shortness of breath. For example, musculoskeletal problem or chest pain.

Magnitude of task

Grade	Symptoms
4	Extraordinary. Becomes short of breath only with extraordinary activity such as carrying very heavy loads on the level, lighter loads uphill, or running. No shortness of breath with ordinary tasks.
3	Major. Becomes short of breath only with such major activities as walking up a steep hill, climbing more than three flights of stairs, or carrying a moderate load on the level.
2	Moderate. Becomes short of breath with moderate or average tasks such as walking up a gradual hill, climbing fewer than three flights of stairs, or carrying a light load on the level.
1	Light. Becomes short of breath with light activities such as walking on the level, washing, or standing.
0	No task. Becomes short of breath with light activities such as walking on the level, washing, or standing.
W	Amount uncertain. Patient’s ability to perform tasks is impaired due to shortness of breath, but amount cannot be specified. Details are not sufficient to allow impairment to be categorized.
X	Unknown. Information unavailable regarding limitation of magnitude of task.
Y	Impaired for reasons other than shortness of breath. For example, musculoskeletal problem or chest pain.

Magnitude of effort

Grade	Symptoms
4	Extraordinary. Becomes short of breath only with the greatest imaginable effort. No shortness of breath with ordinary effort.
3	Major. Becomes short of breath only with effort distinctly submaximal, but of major proportion. Tasks performed without pauses unless the task requires extraordinary effort that may be performed with pauses.
2	Moderate. Becomes short of breath with moderate effort. Tasks performed with occasional pauses and requiring longer to complete than the average person.
1	Light. Becomes short of breath with little effort. Tasks performed with little effort or more difficult tasks performed with frequent pauses and requiring 50–100% longer to complete than the average person might require.
0	No effort. Becomes short of breath at rest, while sitting or lying down.
W	Amount uncertain. Patient’s ability to perform tasks is impaired due to shortness of breath, but amount cannot be specified. Details are not sufficient to allow impairment to be categorized.
X	Unknown. Information unavailable regarding limitation of magnitude of effort.
Y	Impaired for reasons other than shortness of breath. For example, musculoskeletal problem or chest pain.

^*Mahler DA, Weinberg DH, Wells CK et al, 1984. The measurement of dyspnea: Contents, interobserver agreement, and physiologic correlates of two new clinical indexes. Chest 85, 751–758.

Box 7.2B Transition Dyspnoea Index *

Change in functional impairment

Grade	Symptoms
–3	Major deterioration. Formerly working and has had to stop working and has completely abandoned some of usual activities due to shortness of breath.
–2	Moderate deterioration. Formerly working and has had to stop working or has completely abandoned some of usual activities due to shortness of breath.
–1	Minor deterioration. Has changed to a lighter job and/or has reduced activities in number or duration due to shortness of breath. Any deterioration less than preceding categories.
0	No change. No change in functional status due to shortness of breath.
+ 1	Minor improvement. Able to return to work at reduced pace or has resumed some customary activities with more vigour than previously due to improvement in shortness of breath.
+ 2	Moderate improvement. Able to return to work at nearly usual pace and/or able to return to most activities with moderate restriction only.
+ 3	Major improvement. Able to return to work at former pace and able to return to full activities with only mild restriction due to improvement of shortness of breath.
Z	Further impairment for reasons other than shortness of breath. Patient has stopped working, reduced work, or has given up or reduced other activities for other reasons. For example, other medical problems, being ‘laid off’ work, etc.

Change in magnitude of task

Grade	Symptoms
–3	Major deterioration. Has deteriorated two grades or greater from baseline status.
–2	Moderate deterioration. Has deteriorated at least one grade but fewer than two grades from baseline status.
–1	Minor deterioration. Has deteriorated less than one grade from baseline. Patient with distinct deterioration within grade, but has not changed grades.
0	No change. No change from baseline.
+ 1	Minor improvement. Has improved less than one grade from baseline. Patient with distinct improvement within grade, but has not changed grades.
+ 2	Moderate improvement. Able to return to work at nearly usual pace and/or able to return to most activities with moderate restriction only.
+ 3	Major improvement. Has improved two grades or greater from baseline.
Z	Further impairment for reasons other than shortness of breath. Patient has reduced exertional capacity, but not related to shortness of breath. For example, musculoskeletal problem or chest pain.

Change in magnitude of effort

Grade	Symptoms
–3	Major deterioration. Severe decrease in effort from baseline to avoid shortness of breath. Activities now take 50–100% longer to complete than required at baseline.
–2	Moderate deterioration. Some decrease in effort to avoid shortness of breath, although not as great as preceding category. There is great pausing with some activities.
–1	Minor deterioration. Does not require more pauses to avoid shortness of breath, but does things with distinctly less effort than previously to avoid breathlessness.
0	No change. No change in effort to avoid shortness of breath.
+ 1	Minor improvement. Able to do things with distinctly greater effort without shortness of breath. For example, may be able to carry out tasks somewhat more rapidly than previously.
+ 2	Moderate improvement. Able to do things with fewer pauses and distinctly greater effort without shortness of breath. Improvement is greater than preceding category, but not of major proportion.
+ 3	Major improvement. Able to do things with much greater effort than previously with few, if any, pauses. For example, activities may be performed 50–100% more rapidly than at baseline.
Z	Further impairment for reasons other than shortness of breath. Patient has reduced exertional capacity, but not related to shortness of breath. For example, musculoskeletal problem or chest pain.

^*Mahler DA, Weinberg DH, Wells CK, Feinstein AR, 1984. The measurement of dyspnea: Contents, interobserver agreement, and physiologic correlates of two new clinical indexes. Chest 85, 751–758.

In addition, patients can be quizzed regarding the specific movements and tasks that elicit dyspnoea, since this information will provide a guide to the type of functional exercises that address these deficits. For example, if patients identify hair brushing / washing as a task that specifically elicits dyspnoea, exercises that simulate this challenge can be selected. If, on the other hand, the patient reports feeling unsteady or off balance when they get out of breath, this may suggest that they have lumbopelvic dysfunction that can be addressed with specific exercises. The following is a list of suggested questions, which is by no means exhaustive:

• What activities cause you to get out of breath, e.g., gardening, drying after bathing?

• How long can you do the activity for before you stop or slow down?

• What position are you in when you get breathless, e.g., standing?

• How breathless are you when you sit / stand / walk / etc. (a rating scale can be used to quantify this)?

• What activities have you changed or stopped doing because of breathlessness, e.g., gardening?

• How have you modified your activities because of breathlessness, e.g., sit instead of stand, use a walking aid?

• Do you ever lose your balance when you are out of breath, or feel that you need to steady yourself?

• Do you get low back pain, or feel your back is weak, or unstable?

Assessment of dyspnoea during exercise

The most commonly used and well-validated scale for the assessment of dyspnoea during exercise is the Category Ratio scale created by Borg (1982, 1998). This is a general intensity scale with ratio properties that can be used to quantify either breathing or limb effort independently, as well as concurrently within the same exercise test (Borg et al, 2010). A copy of the instrument and instructions for its use can be found in Boxes 7.3 and 7.4 respectively. Typically, the scale is presented to the participant periodically during exercise, and they report their perception verbally or by pointing at the scale. This enables symptom profiles to be generated, as well as isolated ratings at specified intensities of exercise. Furthermore, participants can be asked to exercise to a specified level of perceived effort for the purposes of exercise training, or to compare physical capacity between individuals.

Box 7.3 Borg CR-10 *

^*© Gunnar Borg (Borg, 1998; Borg et al, 2010).

Box 7.4 Borg CR-10 scale instructions *

Basic instruction: 10, ‘Extremely strong – Max P’, is the main anchor. It is the strongest perception (P) you have ever experienced. It may be possible, however, to experience or to imagine something even stronger. Therefore, ‘Absolute maximum’ is placed somewhat further down the scale without a fixed number and marked with a dot ‘•‘. If you perceive an intensity stronger than 10, you may use a higher number.

Start with a verbal expression and then choose a number. If your perception is ‘Very weak’, say 1; if ‘Moderate’, say 3; and so on. You are welcome to use half values (such as 1.5, or 3.5 or decimals, for example, 0.3, 0.8, or 2.3). It is very important that you answer what you perceive and not what you believe you ought to answer. Be as honest as possible and try not to overestimate or underestimate the intensities.

Scaling perceived exertion: We want you to rate your perceived (P) exertion, that is, how heavy and strenuous the exercise feels to you. This depends mainly on the strain and fatigue in your muscles and on your feeling of breathlessness or aches in the chest. But you must only attend to your subjective feelings and not to the physiological cues or what the actual physical load is.

1	is ‘very light’ like walking slowly at your own pace for several minutes.
3	is not especially hard; it feels fine, and it is no problem to continue.
5	you are tired, but you don’t have any great difficulties.
7	you can still go on but have to push yourself very much. You are very tired.
10	this is as hard as most people have ever experienced before in their lives.
•	this is ‘Absolute maximum’, for example, 11 or 12 or higher.

^*Borg G, 1998. Borg’s Perceived Exertion and Pain Scales. Human Kinetics, Champaign, IL, pp. 44–52.

Assessment of dyspnoea during loaded breathing

The Borg CR-10 can also be used during a loaded breathing task to assess breathing effort perception and its response to training (Weiner et al, 2000; Magadle et al, 2002; Weiner et al, 2003; Beckerman et al, 2005). Typically, participants breathe against a series of fixed-pressure threshold loads corresponding to unloaded breathing, and 5, 10, 20 and 30 cmH₂O. After breathing against each load for 1 minute, participants provide an intensity rating using the Borg CR-10. Ideally, the test should be discontinuous such that each rating is discrete, independent of other ratings and unaffected by accumulated inspiratory muscle fatigue; randomization of load presentation is also recommended. The test is susceptible to differences in breathing pattern, so use of a breathing pacer is advisable (a breathing pacer App can be obtained at www.physiobreathe.com/apps).

No published data are currently available to define normal ranges for this test, but ratings of effort are inversely proportional to inspiratory muscle strength (MIP), and the test also exhibits excellent sensitivity to changes in MIP following IMT (Weiner et al, 2000; Magadle et al, 2002; Weiner et al, 2003; Beckerman et al, 2005). Since no normative data exist currently, it is recommended that practitioners / clinics develop their own methods and normative data for identifying patients with abnormally high ratings of dyspnoea. Notwithstanding the lack of published normative data, a look-up chart can be found in Figure 7.1 (see also section ‘Assessment of load / capacity imbalance’, below). It should also be noted that some patients with asthma may have abnormally low ratings (Kikuchi et al, 1994), which is a contraindication for IMT (see Ch. 6, section ‘Contraindications’).

Figure 7.1 Load / capacity imbalance chart. Chart for assessing the extent of functional imbalance between the combined intrinsic and extrinsic loading of the inspiratory muscles, and the capacity of the inspiratory muscles to deliver inspiratory pressure. After breathing against a given load for 60 seconds, the participant rates their effort using the Borg CR-10 scale. Good = no imbalance and above average inspiratory muscle function.
Normal = no imbalance with normal inspiratory muscle function.
Poor = imbalance such that intrinsic and extrinsic inspiratory loading exceeds inspiratory muscle capacity.
Very poor = large imbalance such that intrinsic and extrinsic inspiratory loading exceeds inspiratory muscle capacity considerably. (The chart is based on unpublished data from McConnell and colleagues.)

Assessment of load / capacity imbalance

The look-up chart in Figure 7.1 can be used to assess the extent to which there is a functional imbalance between the combined, intrinsic and extrinsic loading of the inspiratory muscles and the capacity of the inspiratory muscles to deliver inspiratory pressure. The chart is based upon unpublished data collected from normal individuals and those with respiratory disease by McConnell and colleagues over the course of two decades. To undertake the test, the participant breathes against one to three inspiratory loads using the methods described in the section ‘Assessment of dyspnoea during loaded breathing’, above. The resulting Borg CR-10 rating can then be compared with the rating classifications on the chart.

FUNCTIONAL TRAINING EXERCISES

The remainder of this chapter is devoted to a description of a range of functional inspiratory muscle training (IMT) exercises. Two approaches can be taken to the selection of exercises for a particular patient: (1) use a generic set of around 10 exercises that provides a holistic set of benefits (some suggested workout protocols are provided at the end of this chapter), and (2) create a bespoke set of exercises based upon specific patient weaknesses, e.g., situations and tasks that are particularly challenging for the patient. A combination of these two approaches probably represents an optimal solution.

Underlying principles

Functional IMT should be preceded by a 6-week period of Foundation IMT, and the development of good diaphragm breathing technique (see Ch. 6). When embarking upon the Functional phase of training, it is important to ensure that patients have good technique and exercise form, before adding any resistances. Start patients off by performing each exercise with nothing more than a focus on maintaining slow, deep diaphragmatic breathing throughout. Using an external breathing pacer that provides an auditory cue (obtainable via www.physiobreathe.com/apps) can be very helpful for supporting this process, as well as during the functional exercises themselves. Next add an external resistance to inhalation using an inspiratory muscle-training device (IMTD) set on its minimum load. Gradually increase the load on the IMTD over a period of a few weeks until it reaches the prescribed level for the exercise. See Box 7.5 for guidance regarding abdominal bracing and achieving a neutral spine position, as well as the sections on breath control and load setting in Chapter 6. In addition, consider incorporating IMT into interval training, drills or circuits; the IMT can be introduced into the recovery phase of interval training, or it can be a separate station during a drill or circuit.

Box 7.5 Tips for bracing and posture

Bracing

Many of the exercises in this chapter involve an abdominal bracing. Bracing requires co-contraction of muscles that bring about opposing movements. For example, co-contraction of the arm muscles involves simultaneous, forceful contraction of the elbow flexor (biceps) and extensor (triceps) such that the muscles are contracted but the arm neither flexes nor extends (i.e., there is a static contraction of both muscles). This same principle can be applied to the muscles of the abdomen such that they form a stiff, stabilizing corset around the abdomen. The muscle fibres in the multiple layers of the abdominal wall run obliquely across one another, like plywood, forming an extremely strong, yet flexible, cylinder.

Correct bracing requires some practice, and the best place to start is learning how to activate the main compressive muscle, the transversus abdominis. The failure to automatically activate the transversus abdominis is associated with low back pain, but learning how to activate this muscle voluntarily has been shown to restore its automatic function in stabilizing the spine. Reconnecting with the transversus abdominis can be achieved by practising drawing in the anterior abdominal wall toward the spine. The objective is to maximize the reduction in waist girth during this manoeuvre, when this occurs correctly the rectus abdominis and pelvic floor inevitably become involved. Once patients can draw in successfully, they need to practise activating the transversus abdominis and accompanying abdominal muscles using a bracing contraction – one in which the trunk volume changes very little, yet the muscles are contracted forcefully.

Initially, this should be practised with maximal effort, but as patients become more adept at activating the muscles involved the intensity can be reduced, and they will be able to feel (literally) the supportive corset that the manoeuvre creates around the abdomen.

Keep in mind that the use of the term bracing in this book is not intended to imply the adoption of a rigid, inflexible trunk. Instead, it implies a focus on the core muscles as a seat of strength and stability. Moderate co-contraction of the abdominal-stabilizing muscles is the objective, and not inflexible rigidity of the abdominal compartment. The only exceptions to this are static exercises that specifically require trunk rigidity (e.g., planking).

Breathing during abdominal bracing

Inhaling will feel more difficult during abdominal bracing because the downward movement of the diaphragm is opposed by the raised pressure and increased stiffness of the abdominal compartment. Patients will need to work hard to overcome this extra resistance without releasing the brace, but this resistance is providing a very potent training stimulus – not only to the diaphragm but also to the muscles of the abdominal wall. This is because the diaphragm movement increases the pressure inside the abdominal compartment, requiring all of the muscles to contract more forcefully to maintain the brace. In fact, when bracing is performed with maximal effort, this is an excellent exercise in its own right. Diaphragm breathing should be practised during abdominal bracing in the seated or standing position before incorporating it into other exercises. For exercises that involve bracing, add the IMTD only when the patient is able to force their diaphragm into the braced abdominal compartment without losing control of the brace.

Achieving a neutral spine

A neutral spine position is also referred to throughout this chapter; this describes a position in which the pelvis is level, with neither a forward nor a backward tilt (Fig. 7.2). Forward tilt accentuates lumbar lordosis, and backward tilt does the opposite. Both of these produce undesirable loading on the spine.

You can get a feel for this by standing with your back against a wall. If your heels, buttocks, and shoulder blades (upper portion, not the tips) are touching the wall, your pelvis should be in a neutral position.

Before using these exercises, be sure to note the following principles:

• The limb resistances imposed using cords or bands should be low to begin with, but they can be increased as the training progresses. Don’t be too ambitious with the resistance, which is intended primarily to create a postural challenge to the trunk, not to create a resistance-training stimulus to the limbs.

• Ensure elastic resistances are under tension at the start of the exercise (see the previous point for guidance on resistance level).

• For exercises involving hand weights, if these are not available they can be substituted with other items such as cans of food or bags loaded with heavy items.

• For exercises that incorporate abdominal bracing (see section ‘Tips for Bracing and Posture’), add the IMTD only once patients able to force their diaphragm into the braced abdominal compartment.

• The compressive effects of tight clothing can be simulated by wrapping elastic resistance bands around the appropriate areas of the trunk (Fig. 7.3).

Figure 7.2 Neutral spine position; the pelvis is level. (From McConnell AK, 2011. Breathe strong, perform better. Human Kinetics, Champaign, IL, with permission.)

Figure 7.3 Position of elastic resistance to simulate tight-fitting clothing.

The exercises have been designed specifically to minimize the requirement for special equipment. Below is a list of the equipment used, as well as potential alternatives:

Ideal equipment	Alternative equipment
Inspiratory muscle training device	Pursed lips with braced trunk
Swiss ball	Chair with balance cushion
Balance cushion	Close foot stance
Dumbbells (1–10 kg)	Canned food, small sand bags
Small medicine ball (2–10 kg)	Canned food, medium sand bags
Step	Stairs
Elastic resistance band or cord
Exercise mat	Carpeted area
Bounceable ball
Small shopping bag
Chair with and without arms

Where an IMTD is used during an exercise, the loads to be used will be graded as ‘light’ or ‘moderate’. These correspond to the following ‘repetition maximum’ and maximal inspiratory pressure (MIP) percentage settings:

• Light: equivalent to the 50- to 100-repetition maximum (20–40% of MIP, or an effort rating of 2 to 3 on the Borg CR–10 scale)

• Moderate: equivalent to the 20- to 40-repetition maximum (50–60% of MIP, or an effort rating of 4 to 6 on the Borg CR-10 scale).

The exercises are grouped into four sections: (1) trunk strength and lumbopelvic stabilization exercises, (2) dynamic trunk activation exercises, (3) postural control exercises, and (4) pushing and pulling exercises. Each section is subdivided into exercises with ‘Easy’, ‘Moderate’ and ‘Difficult’ classifications. Within each of these classifications, the challenge can be increased progressively, and this is described as appropriate. It is essential that clinical judgement is applied at all times in relation to the suitability of any given exercise for any given patient. For example, the ‘Difficult’ stretches shown below would be entirely unsuitable for a patient with osteoporotic kyphosis.

During most exercises that involve rhythmic movements, there is a requirement to swap breathing phases halfway through a set, i.e., to switch from inhaling whilst overcoming a resistance (concentric phase) to exhaling. This can be achieved easily by pausing between repetitions and adding half a breath cycle. For example, for a bicep curl, at the end of a series of repetitions where inhalation occurs during the concentric phase, pause with the hands raised, exhale and then inhale as the resistance is lowered (eccentric phase). In this way, the inhalation is switched from the concentric to the eccentric phase of the movement.

Individual workouts should be preceded by stretching and mobilizing exercises (see below). An individual workout should consist of around 10 exercises, with an even mix from each of the four sections. Patients should undertake these functional workouts at least three times per week. On other days, Foundation IMT should be undertaken once daily (at least 3 days per week). The difficulty of the exercises should be increased progressively; firstly by adding resistances, and then by progressing through moderate and difficult classifications. It is also good to vary the exercises from time to time to introduce new challenges.

Stretching and mobilizing

Developing range of movement is as important for the thorax as it is for any other part of the body. However, the trunk and rib cage are often overlooked when it comes to these activities, despite the fact that these areas include numerous muscles, their attachments, and associated connective tissue (e.g., the rib cage). The rib cage is potentially a huge source of resistance to inhalation, especially in restrictive diseases such as kyphoscoliosis. Any resistance to thoracic expansion increases the work of breathing and the associated perception of breathing effort. The exercises below are grouped into sets of ‘Easy’, ‘Moderate’ and ‘Difficult’ exercises that stretch the trunk in the anterior, posterior and lateral planes, as well as during rotation. Easy and moderate stretches are based on those of Minoguchi et al (2002). These sets can be used to stretch and mobilize the rib cage in order to free-up rib expansion and reduce breathing effort. Each movement should be sustained at maximum range of movement for around 30 seconds.

Diaphragm breathing can be practised during the stretches. In particular, the tension in the trunk muscles that is created during the anterior stretch over a Swiss ball provides a useful resistance for the diaphragm to work against.

Easy

Easy stretching and mobilizing exercises are performed seated on a chair, in the sequence:

(A) anterior trunk stretch

(B) posterior trunk stretch

(D) seated rotation (perform in both directions).

Moderate

Moderate stretches and mobilizing exercises are performed standing on both feet, in the sequence:

(A) upper trunk anterior stretch

(B) standing posterior stretch

(D) standing rotation (perform in both directions).

Difficult

Difficult stretches and mobilizing exercises are performed over a Swiss ball, on hands and knees, then lying down, in the sequence:

(A) anterior stretch over Swiss ball

(B) lateral stretch over Swiss ball (perform on both sides)

(D) supine rotation (perform in both directions).

Breath control

As was described in Chapter 6, developing breath control is a skill that can and should be practised, because it maximizes breathing efficiency and minimizes the distracting influence of dyspnoea. This can be practised in situations where breathing demand / distress is high; under these conditions, patients should be encouraged to practise deep, slow breath control, and to slow their breathing frequency as much as they can tolerate (a breathing pacer App can be obtained at www.physiobreathe.com/apps). Keeping breathing calm and relaxed under stressful conditions can help to minimize stress and anxiety, and build a sense of mastery.

In addition, below are three further exercises that can help overcome the urge to synchronize breathing with the cadence of movement, which is almost always too high. The exercises involve high-cadence body movements, during which the patient should practise deep, slow, controlled breathing that is deliberately not synchronized with movement (a breathing pacer App can be obtained at www.physiobreathe.com/apps).