Respiratory Muscle Training and SCI 

Since a high-level SCI results in significant respiratory muscle weakness and paralysis, interventions during initial rehabilitation or chronic management may also target improving respiratory muscle strength. Such strength training programs can focus on inspiration, expiration or both.

Inspiratory Muscle Training (IMT) 

Effective IMT may improve lung volumes over time and help decrease a person with SCI’s risk of mortality and morbidity due to respiratory complications such as pneumonia.

IMT provides resistance to the inspiratory muscles: the diaphragm and intercostals, but also accessory muscles. Typically, a handheld spring-loaded device with mouthpiece is used to create resistance to the effort of inspiration. Alternatively, a weight can be positioned on the abdomen in supine to create resistance to abdominal rise as the diaphragm descends during inspiration. While IMT will target strengthening of the whole diaphragm, it may also be a useful adjunct when attempting to recruit a weakened hemi-diaphragm.

Recommendations are for inspiratory strength training sessions to be completed up to 2x/day 5 days/week performed over at least 6-8 weeks, with resistance progressively increased. 

The following is an example program: 

https://aci.health.nsw.gov.au/__data/assets/pdf_file/0003/582825/ACI-SCI-Inspiratory-muscle-training-people-spinal-cord-injury.pdf

Improvements in inspiratory muscle recruitment can be assessed subjectively, but also objectively using spirometry.

IMT can be employed in various positions, in supine but also in sitting wearing an abdominal binder use to:

• apply a constant abdominal pressure to support passive exhalation but also
• position the abdominal contents up against the diaphragm to enhance its ‘domed shape’ and improve its contractile efficiency.

The Australian and New Zealand Physiotherapy Guidelines for people with SCI states the literary evidence provides a weak recommendation that:                          

Functional Electrical Stimulation (FES) 

Although quiet expiration is a passive process, other strength training programs may focus on forced expiratory muscle recruitment of weakened or paralysed abdominal muscles to increase expiratory flow rate for function eg. huff, cough, sneeze, blow nose.

FES can be delivered transcutaneously via electrodes positioned over the abdominal muscles’ nerve motor endplates, utilising the intact reflex arc still present in an upper motor neuron SCI ie. above lesion level of T12/L1. Standard contraindications to the use of FES apply.

Before considering further, it is noted that after spinal shock has resolved, spasticity and/or hypertonicity may develop in weakened or paralysed intercostals but also abdominal muscles. This may result in variable functional benefits and challenges. Therefore, the efficacy of trialling FES of the abdominal muscles needs to be assessed individually. Secondly, FES of the abdominal muscles for increasing expiratory flow rate, is not overly practical unless a training effect improving forced expiratory function can be achieved without FES. Improvements in forced expiratory muscle recruitment (with or without FES) can be assessed subjectively, but also objectively using spirometry.

FES of weakened abdominal muscles may be also trialled in a training program, along with regular core stability exercises to improve general abdominal muscle tone to enhance diaphragm positioning, postural hypotension control, as well as seated posture and balance.

The Australian and New Zealand Physiotherapy Guidelines for people with SCI only provides a consensus statement for a weak recommendation re abdominal muscles FES that: