Adherence to and impact of home-based high-intensity IMT in people with spinal cord injury: a pilot study

Abstract

Study design The pilot study was completed in 5 phases (Control and 4 phases of IMT) incorporating assessments at Baseline 1 (BL1), BL2, Follow-up 1 (F1), F2, F3, and F4. Objective To assess the adherence and impact of a daily high-intensity (80% of max) inspiratory muscle training (IMT) home program with once weekly supervision for people with spinal cord injury (SCI). Setting Assessments: research institution or zoom. IMT: participant’s home. Methods Participants completed daily IMT in IMT Phase 1 and 2, once weekly in IMT Phase 3, self-selected frequency in IMT Phase 4. All phases had one weekly supervised session except IMT Phase 4. Primary outcomes included adherence and a difficulty score [DS (0- not difficult to 10- the most difficult)]. Secondary outcomes included respiratory function and seated balance. Results Data from 10 people with chronic SCI (>1 year) (Cervical level of injury: 6, AIS: A-B, injury duration: 10.9 years 95% CI [3.9, 18.1]) were used in the analysis. Participants completed 69% of their training days in IMT Phase 1 and 65% overall reporting an average DS of 7.4 ± 1.4. Only one participant completed training during IMT Phase 4. One participant’s training load was reduced due to suspected overtraining. Maximal inspiratory pressure (MIP), sustained MIP (SMIP), and total power (TP), improved significantly (p < 0.05) from BL2 to F1. Conclusion Our data suggest that people with SCI can perform high-intensity IMT at home to improve inspiratory performance. It is strongly recommended that participants be intermittently monitored for adherence and safety. ClinicalTrials.gov Registration number: NCT04210063.

Comparison of two inspiratory muscle training protocols in people with spinal cord injury: a secondary analysis

“…Characteristics used as criteria for matching did not differ significantly between groups (height or adherence), however people in the F-IMT group were younger ( p = 0.002), had a shorter duration of injury ( p = 0.002), weighed less ( p = 0.030), and had a higher PI max ( p = 0.041) at baseline than the T-IMT group (Table 3 ). Further descriptive information about the overall trial samples can be found in the original publications [ 4 , 7 ].…”

“…Inspiratory muscle strength outcomes in two published original IMT studies in people with chronic SCI were compared. One study [ 4 ] used F-IMT (PrO2, PrO2Fit, Smithfield, RI, USA) and the second [ 7 ] used T-IMT (Threshold-IMT, Philips Respironics, Chichester, UK). Both studies had approval from affiliated human research ethics boards and were registered prior to trial commencement (NCT04210063; ANZCTR12612000929808).…”

“…The Hyp’Air Pulmonary Function Test (Medisoft, Sorinnes, Belgium) was used to measure PI max from functional residual capacity in a seated posture at baseline while the MicroRPM (CareFusion, UK) was used to measure PI max weekly during the T-IMT study. In the F-IMT study 11 participants with chronic SCI completed F-IMT at 80% of a daily PI max for a target frequency of 7 days/week in their homes, supervised once weekly for 4–20 weeks, with variability in duration due to changes in the study protocol during the COVID-19 pandemic [ 4 ]. In the T- IMT study, 30 participants with acute SCI, and 32 participants with chronic SCI completed 2 daily supervised T-IMT sessions in the hospital (participants with acute SCI) or in their homes (participants with chronic SCI, >1 year duration of injury) 5 days/week for 6 weeks [ 7 ].…”

“…One option to combat respiratory muscle weakness is respiratory muscle training (RMT). RMT encompasses interventions targeted to improve respiratory muscle strength and function including: inspiratory muscle training (IMT) [ 3 , 4 ], expiratory muscle training (EMT) [ 5 ], combined IMT and EMT [ 6 , 7 ], singing [ 8 ], breathing with abdominal weights [ 9 ], abdominal functional electrical stimulation [ 10 ], and iso- or normo-capnic hyperpnoea [ 11 ]. Two meta-analyses report significant positive effects of RMT for people with SCI [ 12 , 13 ].…”

“…Threshold devices contain a spring-loaded valve that opens to allow airflow when the trainee reaches the set pressure threshold during an inspiration. Flow-resistance training (F-IMT) devices have also been used to train people with SCI [ 3 , 4 ]. F-IMT devices have small, fixed openings that create resistance as the trainee inspires.…”