Respiratory muscle training in individuals with spinal cord injury: effect of training intensity and -volume on improvements in respiratory muscle strength

Abstract

Study design Retrospective cohort study. Objectives To investigate the effect of training intensity and-volume on improvements in respiratory muscle strength in individuals with spinal cord injury (SCI). Setting SCI rehabilitation center in Switzerland. Methods Inpatients with SCI, lesion level C4-T12, who had at least 10 individualized inspiratory muscle training sessions with respiratory function measurements before and after the training period. Multiple regression analysis with natural logarithmic (ln) transformation of the outcome values was used to examine the effect of training intensity and-volume, lesion level and completeness, and baseline respiratory muscle strength on improvements in respiratory muscle strength. Results Overall, 67 individuals were analyzed. Variation in PI max was explained by PI max at baseline and training intensity. This adjusted effect size suggested a 7% (95% CI 2.8 to 11.6%) increase in PI max per 10 units of increase in training intensity. Controlling for the variation in baseline PE max , the effect of training intensity on PE max was conditional on AIS (p < 0.021). While individuals with motor complete lesions showed a 6.8% (95% CI 2.1 to 11.7%) increase in PE max per 10 units of increase in training intensity, the corresponding adjusted effect size in those with motor incomplete lesions was 0.1% (95% CI −4.3 to 4.5%). The full models explained 57 and 60% of the variance of lnPI max and lnPE max , respectively. Conclusion The intensity of inspiratory muscle training was more relevant than training volume for the improvement of respiratory muscle strength in individuals with SCI. Thus, training intensity should be chosen as high as possible.

Effects of Respiratory Muscle Training on Baroreflex Sensitivity, Respiratory Function, and Serum Oxidative Stress in Acute Cervical Spinal Cord Injury

“…Furthermore, compared with the non-RMT group, the RMT group showed significant improvements in MIP at 1 month and in tidal volume and RSBI at 6 months. Several recent studies showed that RMT can significantly improve respiratory function based on MIP, MEP, and FVC with 4–12 weeks training [ 54 , 59 , 60 ]. In 67 individuals with SCI at levels C4–T12, Raab et al found that at least 10 individualized inspiratory muscle training sessions produced a 7% increase in MIP and a 6.8% increase in MEP per 10 units of increase in training intensity [ 59 ].…”

“…Several recent studies showed that RMT can significantly improve respiratory function based on MIP, MEP, and FVC with 4–12 weeks training [ 54 , 59 , 60 ]. In 67 individuals with SCI at levels C4–T12, Raab et al found that at least 10 individualized inspiratory muscle training sessions produced a 7% increase in MIP and a 6.8% increase in MEP per 10 units of increase in training intensity [ 59 ]. Shin et al admitted 104 patients with SCI for 4–8 weeks of in-patient clinical rehabilitation [ 60 ].…”

Respiratory Training and Plasticity After Cervical Spinal Cord Injury

“…Typical MST paradigms in the clinic consist of three sessions (with 25–30 repetitions), 3–5 days per week, 4–8 weeks ( Carpinelli and Otto, 1998 ; Schlumberger et al, 2001 ; Rhea et al, 2002 ; Sapienza et al, 2011 ). The intensity of MST can directly affect improvement in respiratory muscle strength ( Raab et al, 2019 ).…”

“…There are two main MST strategies: resistance and threshold training. Resistance MST consists of breathing through a small diameter hole, making the participant breathe harder due to the limited airflow ( Sapienza and Wheeler, 2006 ; Berlowitz and Tamplin, 2013 ; Raab et al, 2019 ). It can be targeted toward either inspiratory or expiratory muscles ( Roth et al, 2010 ) or combined ( Kim et al, 2017 ).…”

“…Combined training resulted in increased forced vital capacity and expiratory volume, demonstrating improved pulmonary function compared to the respiratory muscle training alone and control group (Kim et al, 2017). Threshold MST forces the individual to modulate their breathing to overcome a spring-loaded valve controlling the airflow (Sapienza and Wheeler, 2006;Galeiras Vazquez et al, 2013;Raab et al, 2019). Resistance and threshold MST result in improved breathing, facilitates weaning from mechanical ventilation (Aldrich et al, 1989;Martin et al, 2011;Smith et al, 2014), and has beneficial effects in secondary respiratory behaviors [e.g., sneezing, sniffing, or coughing (Postma et al, 2015;Aslan et al, 2016;Legg Ditterline et al, 2018;Shin et al, 2019)].…”