Peripheral muscle strength is an important component in respiration. Respiratory muscles correspond with peripheral muscles to control the posture needed to perform a task, while adequately supplying air to utilize an O2 to CO2 ratio needed to complete the task. The integration of the respiratory and peripheral muscles also regulates the duration at which it takes metabolic homeostasis to occur within the body. During inspiration, the diaphragm descends down towards the pelvic diaphragm or pelvic bowl, while the external intercostal contract concentrically, pulling the ribs up through external rotation and torsion, expanding the chest cavity and decreasing intrapulmonary pressure (negative) within the lungs, allowing for an increase in air to move into the lungs. During expiration, the transverse abdominis, internal intercostals, and the oblique muscles concentrically contract to pull the ribcage (ribs internally rotate and pulled down) and pelvis (posterior tilt) closer together, increasing intrapulmonary pressure within the thoracic cavity, increasing expiratory volumes of air. These same muscles that are important for inhalation and exhalation aid in our ability to stand, sit, walk, jump, or run at any given moment.
Hodges (2001), noted that as inspiration increased during movement, respiratory muscles (inspiration and expiration) increased their role as respiratory muscles and decreased their activity as postural muscular control muscles, comprising trunk stability and dynamic movement integration between upper and lower halves.
Resistance training improves mechanical muscle function, it increases bone mineral density, connective tissue strength and can increase VO2 max. Resistance training has shown to be an important therapeutic approach to improving diaphragmatic breathing in pulmonary diseases. Resistance training increases adaptive changes in skeletal muscle and improves postural stability, respiratory rate, while also leading to adaptive changes in neuromuscular function. These adaptive changes in skeletal neuromuscular function have been linked to increased maximal contractile forces and power output in both children and adults. Resistance training not only improves mechanical muscle function, it also increases motor unit recruitment in skeletal muscle, increases frequency excitability and proprioceptive awareness in respiratory muscles. Due to alterations in the CFTR synthesis in cystic fibrosis, resistance training supplemented with diaphragmatic breathing exercises could be a beneficial starting point to respiratory capacity in CF. Resistance that encourages increased skeletal muscle strength will encourage better motor and sensory awareness within the body. Improving proprioceptive feedback during exercise can encourage better sensory awareness through space, resulting in better utilization of respiratory and dynamic postural muscles.
The increase in the rhythmic utilization of these muscles would reduce energy expenditure during every day activities, decreasing the amount of air needed to perform the activities, while increasing the capacity to consume more air if needed. This is an important component because in situations where respiratory function is increased due to postural and/or daily stress or exercise fatigue, the ability of respiratory muscles to perform their postural task is reduced. The increase in energy demand increases physiological and psychological recruitment increasing the rate of fatigue.
Resistance training has shown to be an important therapeutic intervention for improving lung function in cystic fibrosis. Resistance training increases adaptive changes in skeletal muscle and improves postural stability, while also causes adaptive changes in neuromuscular function. These adaptive changes in skeletal neuromuscular function have been linked to increased respiratory muscle strength and increased lung volume potential. Resistance training not only improves mechanical muscle function, it increases motor unit recruitment and its frequency excitability during and after exercise. The increase in postural and respiratory muscle strength decreases neuromuscular and physiological stress on the body, reducing respiratory demands during everyday movements such as; standing, sitting, walking and running. The direct integration of these systems generates a potential to improve lung capacity by integrating resistance training into one’s exercise routine; if not to improve overall strength, then to improve overall respiratory strength and capacity.
Hodges, P. W., Heijnen, I., & Gandevia, S. C. (2001). Postural activity of the diaphragm is reduced in humans when respiratory demand increases. The Journal of Physiology, 15(537), 999-1008.