The diaphragm controls breathing at an involuntary level, but a patient can be taught breathing control by correct use of the diaphragm and relaxation of accessory muscles. Diaphragmatic breathing exercises are designed to improve the efficiency of ventilation, decrease the work of breathing, increase the excursion (decent or ascent) of the diaphragm, and improve gas exchange and oxygenation. Diaphragmatic breathing exercises are also used to mobilize lung secretions during postural drainage.
Procedures:

1. Prepare the patient in a relaxed and comfortable position such as a semi–Fowler’s position (reclined sitting) evaluate thee breathing pattern, and demonstrate the correct method of diaphragmatic breathing.
2. Place your hand (s) on the rectus abdominis just below the anterior costal margin.
3. Ask the patient to breathe in slowly and deeply through the nose. Have the patient keep the shoulders relaxed and upper chest quiet, allowing the abdomen to rise.
4. Then tell the patient to slowly let all the air out using controlled expiration.
5. Have the patient practice this three or four times and then rest. Do not allow the patient to hyperventilate.
6. Have the patient place his or her own hand below the anterior costal margin and feel the contraction of the abdominal muscles, which occurs with controlled expiration or coughing.
7. After the patient understands and is able to breathe using a diaphragmatic pattern, suggest that he or she breath in through the nose and out through the mouth.
8. Practice diaphragmatic breathing in a variety of positions (sitting, standing) and during activity. (walking and climbing stairs)

Note: The effect of diaphragmatic breathing exercises on ventilation, oxygenation and excursion of the diaphragm in normal subjects and in patients with pulmonary disorders remains unclear. Studies have both supported and refuted. the positive impact of diaphragmatic breathing exercises on each of these areas of function. Diaphragmatic breathing exercises will continue to be an integral part of most chest physical therapy program as research on the effects of diaphragmatic breathing continues.

Ventilatory Muscle Training
The process of improving the strength or endurance of the muscles of breathing is known as ventilatory muscle training (VMT). This technique usually focuses on training the muscles of patients with a variety of acute or chronic pulmonary disorders associated with weakness, atrophy, or inefficiency of the muscles of inspiration, specifically the diaphragm and external intercostals.
A. Diaphragmatic training using weights:

1. Have the patient assume a supine or slightly head up position.
2. Be sure that the patient knows how to breathe in by primarily using the diaphragm.
3. Place a small weight (3 to 5 lb) over the epigastric region of the patient’s abdomen.
4. Tell the patient to breathe in deeply while trying to keep the upper chest quiet. The resistance should not interfere with full excursion of the diaphragm and normal rise of the epigastric area.
5. Gradually increase the time that the patient breathes against the resistance of the weight. The weight can be increased when the patient can sustain the diaphragmatic breathing pattern without the use of accessory muscles of inspiration for 15 minutes.
6. Manual resistance or positioning can also be used to strengthen the diaphragm. In the head down position the abdominal contents move superiorly and provide resistance to the diaphragm as it contracts and descends.

Note: Although this method of strengthening the diaphragm is often suggested for patients with weakness, the results of a study of normal subjects indicate that the effectiveness of this method of strengthening is questionable. In another study with patients with cervical level spinal cord injuries, abdominal weight training and inspiratory resistance training were both effective methods of ventilatory muscle training to improve respiratory muscles strength and endurance. Further studies are warranted to determine the efficacy of abdominal weight training as well as other forms of VMT.
B. Inspiratory resistance training:

1. Specifically designed breathing devices (resistors) are used to improve the strength and endurance of the muscles of inspiration and decrease the occurrence of inspiratory muscle fatigue.
2. Procedure:
• The patient inhales through a hand held resistive training device that he or she places in the mouth. Inspiratory resistive training devices are narrow tubes of varying diameters that provide resistance to airflow during inspiration and therefore place resistance on inspiratory muscles to improve strength or endurance. The narrower the diameter of the airway, the greater the resistance.
• The patient inhales through the tube for a specified period of time several time each day. The time is gradually increased to 20 to 30 minutes each training session to increase inspiratory muscle endurance.
• As the patient’s strength and endurance improve, the diameter of the hand–held tube is decreased. The commercially available resistive devices have six different diameters to provide levels of resistance appropriate for each patient.

C. Incentive respiratory spirometer:

1. This is a form of low level resistance training that emphasizes sustained maximal inspiration. A synonymous term is sustained maximal inspiratory maneuver, which is performed with or without the use of a spirometer. The patient inhales through a spirometer that provides visual or auditory feedback as the patient breathes in as deeply as possible. Incentive spirometer increases the volume of air inspired and has been used to prevent alveolar collapse in postoperative conditions and to strengthen weak inspiratory muscles in patients with neuromuscular disorders.
2. Procedures
• Place the patient in a comfortable position (supine or semi upright).
• Have the patient take three or four slow, easy breaths.
• Have the patient maximally exhale with the fourth breath.
• Then have the patient place the spirometer and hold the inspiration for several seconds.
• This sequence is repeated 5 to 20 times several times peer day.

D. Precaution:
Avoid prolonged periods of any form of resistance training for inspiratory muscles. Unlike muscles of the extremities, the diaphragm cannot totally rest to recover from a session of resistant exercises. Use of accessory muscles of inspiration (neck muscles) is a sign that the diaphragm is beginning to fatigue.