Hva påvirker endring i kardiorespiratorisk form som følge av høyintensiv trening hos lungetransplanterte?: En analyse av en gjennomført randomisert kontrollert studie

Abstract

Introduction: Among patients who have undergone lung transplantation (LTx), low levels of cardiarespiratory fitness (CRF) is reported, despite normal lung function. Low CRF is probably due to, among other things, prolonged inactivity and use of immunosuppressive drugs, with accompanying skeletal muscle dysfunction. Improved CRF through exercise is likely to result in improved prospects, as well as other favorable health outcomes for the patients. However, there is little evidence of exercise effects after LTx, and therefore a 20-week high-intensity randomized controlled exercise trial was conducted with effect on peak maximum oxygen uptake (VO2peak) as the primary outcome; the HILT study. However, the results were not in line with the hypotheses of improved CRF at group level. The purpose was to investigate what affected the training effect on CRF after high-intensity interval training (HIIT) in LTx patients, to assess and report the adherence and participation in the training intervention, and to identify whether there were participant characteristics associated with the training response. Methods: This is a retrospective analysis of participants in the exercise group (n = 21) in the HILT study. Only the endurance training in the intervention is included here, with cardiorespiratory fitness (directly measured as VO2peak) as the primary outcome. The exercise group followed a standardized exercise program three times a week for 20 weeks with an individual training instructor. The exercise program mainly consisted of HIIT performed by uphill walking on a treadmill (at 85-95% of peak heart rate). Planned and completed exercise was quantified with training impulse (TRIMP), which indicates each participant's exercise dose for each session. Relative dose intensity (RDI), which describes the relationship between planned and completed exercise dose, was used to assess feasibility/adherence and participation, as well as dose response for the entire intervention. In addition, RDI was used to identify training sessions where the completed exercise dose was modified. Results: The average planned and completed exercise dose was 333 565 ± 2496 and 206 488 ± 96 958 TRIMP respectively, which corresponds to an average RDI of 66 ± 29%. 5 (24%) of 21 participants permanently discontinued the exercise intervention before week 20. All participants had exercise interruptions (missing ³3 consecutive training sessions) and training sessions that required modification of the exercise dose for various reasons. The correlation between RDI and exercise response was moderate (r=0.56, p=0.009), but there was a significant difference in change in VO2peak between participants who completed ³70% and those who completed <70% of planned exercise dose (p=0.024). Among participant characteristics associated with exercise response, time since transplantation (r=-0.68) and lung function (measured as FEV1 in % of predicted values at inclusion) (r=0.58) were of greatest importance. Participants with chronic lung allograft dysfunction (CLAD) had significantly poorer exercise response than participants without: -3.6 ± 10% vs 8.2 ± 9.6% (p=0.041). Participants with ³30 months since LTx showed significantly poorer exercise response compared with those who had LTx <30 months before (p=0.002). Conclusion: RDI can provide useful information about adherence with scheduled exercise after LTx, and with good correlation with change in VO2peak. However, patients should start training fairly quickly after LTx, as the exercise response dropped drastically with time since transplantation.