Discharge frequencies of single motor units in human diaphragm and parasternal muscles in lying and standing.

Single motor unit discharge was measured directly in diaphragm and parasternal intercostal muscles to determine whether neural drive to human inspiratory muscles changes between lying and standing. The final discharge frequency of diaphragmatic motor units increased slightly, by 1 Hz (12%; P < 0.01), when subjects were standing [182 units, median 9.1 Hz (interquartile range 7.6-11.3 Hz)] compared with lying supine [159 units, 8.1 Hz (6.6-10.3 Hz)]. However, this increase with standing occurred in only two of six subjects, in one of whom tidal volume increased significantly during standing. Parasternal intercostal motor unit final discharge frequencies did not differ between standing [116 units, 8.0 Hz (6.6-9.6 Hz)] and lying [124 units, 8.4 Hz (7.0-10.3 Hz)]. The discharge frequencies at the onset of inspiration did not differ between lying and standing for either muscle. A larger proportion of motor units in both inspiratory muscles had postinspiratory or tonic expiratory activity for lying compared with standing (15 vs. 4%; P < 0.05). We conclude that there is no major difference in the phasic inspiratory drive to the diaphragm with the change in posture.

[1]  T. Dick,et al.  Correlation of recruitment order with axonal conduction velocity for supraspinally driven diaphragmatic motor units. , 1987, Journal of neurophysiology.

[2]  J. Mead,et al.  Measurement of the separate volume changes of rib cage and abdomen during breathing. , 1967, Journal of applied physiology.

[3]  N. Cherniack,et al.  Differential costal and crural diaphragm compensation for posture changes. , 1985, Journal of applied physiology.

[4]  N. Burki.  The effects of changes in functional residual capacity with posture on mouth occlusion pressure and ventilatory pattern. , 2015, The American review of respiratory disease.

[5]  A. Grassino,et al.  Diaphragm interference pattern EMG and compound muscle action potentials: effects of chest wall configuration. , 1997, Journal of applied physiology.

[6]  S. Loring,et al.  Effect of posture on upper and lower rib cage motion and tidal volume during diaphragm pacing. , 1984, The American review of respiratory disease.

[7]  T A Sears,et al.  The proprioceptive reflex control of the intercostal muscles during their voluntary activation , 1970, The Journal of physiology.

[8]  J. Sharp,et al.  Effects of body position change on thoracoabdominal motion. , 1978, Journal of applied physiology: respiratory, environmental and exercise physiology.

[9]  T A Sears,et al.  Muscle activity during chest wall restriction and positive pressure breathing in man. , 1978, Respiration physiology.

[10]  M. Cheeseman,et al.  Phrenic afferent contribution to reflexes elicited by changes in diaphragm length. , 1990, Journal of applied physiology.

[11]  J. Kinney,et al.  Effect of posture on the ventilatory response to CO2. , 1982, Journal of applied physiology: respiratory, environmental and exercise physiology.

[12]  R. J. Harrison,et al.  The Lung: Clinical Physiology and Pulmonary Function Tests , 1956 .

[13]  O. Wade,et al.  Movements of the thoracic cage and diaphragm in respiration * , 1954, The Journal of physiology.

[14]  S. Gandevia,et al.  Pulmonary afferents are not necessary for the reflex inhibition of human inspiratory muscles produced by airway occlusion. , 1997, Journal of neurophysiology.

[15]  J. Mead,et al.  Mechanical interaction between the diaphragm and rib cage. , 1973, Journal of applied physiology.

[16]  B. Svensson,et al.  Overlapping electron traps in n‐type silicon studied by capacitance transient spectroscopy , 1989 .

[17]  S. Loring,et al.  Analysis of volume displacement and length changes of the diaphragm during breathing. , 1982, Journal of applied physiology: respiratory, environmental and exercise physiology.

[18]  L. Lindstrom,et al.  Influence of bipolar esophageal electrode positioning on measurements of human crural diaphragm electromyogram. , 1996, Journal of applied physiology.

[19]  S. Gandevia,et al.  Discharge properties and recruitment of human diaphragmatic motor units during voluntary inspiratory tasks , 1999, The Journal of physiology.

[20]  A. Troyer.  Mechanical role of the abdominal muscles in relation to posture , 1983 .

[21]  G Ferrigno,et al.  Human respiratory muscle actions and control during exercise. , 1997, Journal of applied physiology.

[22]  J A Daubenspeck,et al.  Diaphragmatic electromyography using a multiple electrode array. , 1989, Journal of applied physiology.

[23]  J. Desmedt.  Motor control mechanisms in health and disease , 1983 .

[24]  J. Sharp,et al.  Activity of respiratory muscles in upright and recumbent humans. , 1981, Journal of applied physiology: respiratory, environmental and exercise physiology.

[25]  J. Mead,et al.  Reflex compensation of spontaneous breathing when immersion changes diaphragm length. , 1985, Journal of applied physiology.

[26]  S. Gandevia,et al.  Changes in human diaphragmatic electromyogram with positive pressure breathing , 1986, Neuroscience Letters.

[27]  S. Gandevia,et al.  Phrenic nerve conduction times and twitch pressures of the human diaphragm. , 1985, Journal of applied physiology.

[28]  D. Kernell.  Functional properties of spinal motoneurons and gradation of muscle force. , 1983, Advances in neurology.

[29]  J. Sharp,et al.  Function of the isolated paced diaphragm and the cervical accessory muscles in C1 quadriplegics. , 1979, The American review of respiratory disease.

[30]  J. B. Leeper,et al.  Neural drive to the diaphragm in patients with severe COPD. , 1997, American journal of respiratory and critical care medicine.

[31]  R. Johansson,et al.  Changes in motoneurone firing rates during sustained maximal voluntary contractions. , 1983, The Journal of physiology.

[32]  A E Grassino,et al.  Influence of lung volume and electrode position on electromyography of the diaphragm. , 1976, Journal of applied physiology.

[33]  M. Sackner,et al.  Validation of respiratory inductive plethysmography using different calibration procedures. , 2015, The American review of respiratory disease.

[34]  F. J. Clark,et al.  On the regulation of depth and rate of breathing , 1972, The Journal of physiology.

[35]  D. Kernell.  The Adaptation and the Relation between Discharge Frequency and Current Strength of Cat Lumbosacral Motoneurones Stimulated by Long‐Lasting Injected Currents , 1965 .

[36]  O. Wade,et al.  The Effect of Posture on Diaphragmatic Movement and Vital Capacity in Normal Subjects , 1951, Thorax.

[37]  S. Iscoe,et al.  Recruitment and discharge frequency of phrenic motoneurones during inspiration. , 1976, Respiration physiology.

[38]  J. Sharp,et al.  Electrical and mechanical activity of the diaphragm accompanying body position in severe chronic obstructive pulmonary disease. , 2015, The American review of respiratory disease.

[39]  D. Frazier,et al.  Diaphragm afferent modulation of phrenic motor drive. , 1987, Journal of applied physiology.

[40]  M. Decramer,et al.  Coupling between triangularis sterni and parasternals during breathing in dogs. , 1986, Journal of applied physiology.

[41]  F. Gigliotti,et al.  Chest wall kinematics and respiratory muscle action in walking healthy humans. , 1999, Journal of applied physiology.

[42]  S C Gandevia,et al.  Human diaphragmatic EMG: changes with lung volume and posture during supramaximal phrenic stimulation. , 1986, Journal of applied physiology.

[43]  J. Rigg,et al.  Effect of posture on the ventilatory response to CO2. , 1974, Journal of applied physiology.

[44]  C. Bolton,et al.  Needle electromyography of the diaphragm , 1992, Muscle & nerve.

[45]  T Takishima,et al.  Influence of body position on dynamic compliance in young subjects. , 1977, Journal of applied physiology: respiratory, environmental and exercise physiology.

[46]  J Moxham,et al.  Bilateral magnetic stimulation of the phrenic nerves from an anterolateral approach. , 1996, American journal of respiratory and critical care medicine.

[47]  F. Zechman,et al.  Measurement of mouth occlusion pressure as an index of respiratory centre output in man. , 1977, Clinical science and molecular medicine.

[48]  J. B. Leeper,et al.  Discharge frequencies of parasternal intercostal and scalene motor units during breathing in normal and COPD subjects. , 1996, American journal of respiratory and critical care medicine.

[49]  J. H. Comroe.  The Lung. Clinical Physiology and Pulmonary Function Tests , 1956 .