Exercise limitation following transplantation

A century of exercise physiology: effects of muscle contraction and exercise on skeletal muscle Na+,K+-ATPase, Na+ and K+ ions, and on plasma K+ concentration-historical developments

This historical review traces key discoveries regarding K+ and Na+ ions in skeletal muscle at rest and with exercise, including contents and concentrations, Na+,K+-ATPase (NKA) and exercise effects on plasma [K+] in humans. Following initial measures in 1896 of muscle contents in various species, including humans, electrical stimulation of animal muscle showed K+ loss and gains in Na+, Cl- and H20, then subsequently bidirectional muscle K+ and Na+ fluxes. After NKA discovery in 1957, methods were developed to quantify muscle NKA activity via rates of ATP hydrolysis, Na+/K+ radioisotope fluxes, [3H]-ouabain binding and phosphatase activity. Since then, it became clear that NKA plays a central role in Na+/K+ homeostasis and that NKA content and activity are regulated by muscle contractions and numerous hormones. During intense exercise in humans, muscle intracellular [K+] falls by 21 mM (range - 13 to - 39 mM), interstitial [K+] increases to 12-13 mM, and plasma [K+] rises to 6-8 mM, whilst post-exercise plasma [K+] falls rapidly, reflecting increased muscle NKA activity. Contractions were shown to increase NKA activity in proportion to activation frequency in animal intact muscle preparations. In human muscle, [3H]-ouabain-binding content fully quantifies NKA content, whilst the method mainly detects α2 isoforms in rats. Acute or chronic exercise affects human muscle K+, NKA content, activity, isoforms and phospholemman (FXYD1). Numerous hormones, pharmacological and dietary interventions, altered acid-base or redox states, exercise training and physical inactivity modulate plasma [K+] during exercise. Finally, historical research approaches largely excluded female participants and typically used very small sample sizes.

Exercise interventions for adults after liver transplantation

BACKGROUND

The finding that exercise is inversely related to metabolic syndrome after transplantation is novel and suggests that exercise interventions might provide a means for reducing metabolic syndrome complications in liver transplantation recipients. The use of exercise for increasing the physical activity daily levels by more frequent, higher intensity, and longer duration of training sessions, or the sum of these components may be necessary to counteract the effects of the pretransplant reduced activity, metabolic disturbances, and post-transplant immunosuppression, as well as improve physical function and aerobic capacity following liver transplantation. Regular physical activity has a long-term positive impact on recovery following various surgical procedures including transplantation, giving people the opportunity to return to an active life with their families, in society, and in their professional life. Likewise, specific muscle strength training may attenuate the loss of strength after liver transplantation.

OBJECTIVES

To evaluate the benefits and harms of exercise-based interventions in adults after liver transplantation compared to no exercise, sham interventions, or another type of exercise.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 2 September 2022.

SELECTION CRITERIA

We included randomised clinical trials in liver transplantation recipients comparing any type of exercise with no exercise, sham interventions, or another type of exercise.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. all-cause mortality; 2. serious adverse events; and 3. health-related quality of life. Our secondary outcomes were 4. a composite of cardiovascular mortality and cardiac disease; 5. aerobic capacity; 6. muscle strength; 7. morbidity; 8. non-serious adverse events; and 9. cardiovascular disease post-transplantation. We assessed risk of bias of the individual trials using RoB 1, described the interventions using the TIDieR checklist, and used GRADE to assess certainty of evidence.

MAIN RESULTS

We included three randomised clinical trials. The trials randomised 241 adults with liver transplantation, of which 199 participants completed the trials. The trials were conducted in the USA, Spain, and Turkey. They compared exercise versus usual care. The duration of the interventions ranged from two to 10 months. One trial reported that 69% of participants who received the exercise intervention were adherent to the exercise prescription. A second trial reported a 94% adherence to the exercise programme, with participants attending 45/48 sessions. The remaining trial reported a 96.8% adherence to the exercise intervention during the hospitalisation period. Two trials received funding; one from the National Center for Research Resources (US) and the other from Instituto de Salud Carlos III (Spain). The remaining trial did not receive funding. All trials were at an overall high risk of bias, derived from high risk of selective reporting bias and attrition bias in two trials. The results on all-cause mortality showed a higher risk of death in the exercise group versus the control group, but these results are very uncertain (risk ratio (RR) 3.14, 95% confidence interval (CI) 0.74 to 13.37; 2 trials, 165 participants; I² = 0%; very low-certainty evidence). The trials did not report data on serious adverse events excluding mortality or non-serious adverse events. However, all trials reported that there were no adverse effects associated with exercise. We are very uncertain on whether exercise compared with usual care has a beneficial or harmful effect on health-related quality of life assessed using the 36-item Short Form Physical Functioning subscale at the end of the intervention (mean difference (MD) 10.56, 95% CI -0.12 to 21.24; 2 trials, 169 participants; I² = 71%; very low-certainty evidence). None of the trials reported data on composite of cardiovascular mortality and cardiovascular disease, and cardiovascular disease post-transplantation. We are very uncertain if there are differences in aerobic capacity in terms of VO2peak at the end of the intervention between groups (MD 0.80, 95% CI -0.80 to 2.39; 3 trials, 199 participants; I² = 0%; very low-certainty evidence). We are very uncertain if there are differences in muscle strength at end of the intervention between groups (MD 9.91, 95% CI -3.68 to 23.50; 3 trials, 199 participants; I² = 44%; very low-certainty evidence). One trial measured perceived fatigue using the Checklist Individual Strength (CIST). Participants in the exercise group showed a clinically important lower degree of fatigue perception than participants in the control group, with a mean reduction of 40 points in the CIST (95% CI 15.62 to 64.38; 1 trial, 30 participants).  We identified three ongoing studies.

AUTHORS' CONCLUSIONS

Based on very low-certainty evidence in our systematic review, we are very uncertain of the role of exercise training (aerobic, resistance-based exercises, or both) in affecting mortality, health-related quality of life, and physical function (i.e. aerobic capacity and muscle strength) in liver transplant recipients. There were few data on the composite of cardiovascular mortality and cardiovascular disease, cardiovascular disease post-transplantation, and adverse event outcomes. We lack larger trials with blinded outcome assessment, designed according to the SPIRIT statement and reported according to the CONSORT statement.

Chronotropic Incompetence after Heart Transplantation Is Associated with Increased Mortality and Decreased Functional Capacity

INTRODUCTION

The contribution of chronotropic incompetence to reduced exercise tolerance after a heart transplant is well known, but its role as a prognostic marker of post-transplant mortality is unclear. The aim of this study is to examine the relationship between post-transplant heart rate response (HRR) and survival.

METHODS

We performed a retrospective analysis of all adult heart transplant recipients at the University of Pennsylvania between the years 2000 and 2011 who underwent a cardiopulmonary exercise test (CPET) within a year of transplant. Follow-up time and survival status were observed through October 2019, using data merged from the Penn Transplant Institute. HRR was calculated by subtracting the resting HR from the peak exercise HR. The association between HRR and mortality was analyzed using Cox proportional hazard models and Kaplan-Meier analysis. The optimal cut-off point for HRR was generated by Harrell's C statistic. Patients with submaximal exercise tests were excluded, defined by a respiratory exchange ratio (RER) cut-off of 1.05.

RESULTS

Of 277 patients with CPETs performed within a year post-transplant, 67 were excluded for submaximal exercise. In the 210 included patients, the mean follow-up time was 10.9 years (Interquartile range (IQR) 7.8-14). Resting HR and peak HR did not significantly impact mortality after adjusting for covariates. In a multivariable linear regression analysis, each 10-beat increase in heart rate response was associated with a 1.3 mL/kg/min increase in peak V_O2 and a 48 s increase in the total exercise time. Each beat/min increase in HRR was associated with a 3% reduction in the hazard of mortality (HR 0.97; 95% CI 0.96-0.99, p = 0.002). Using the optimal cut-off point generated by Harrell's C statistic, survival was significantly higher in patients with an HRR > 35 beats/min compared to those with an HRR < 35 beats/min (log rank p = 0.0012).

CONCLUSION

In heart transplant patients, a low HRR is associated with increased all-cause mortality and decreased exercise capacity. Additional studies are needed to validate whether targeting HRR in cardiac rehabilitation may improve outcomes.

Early Cardiopulmonary Fitness after Heart Transplantation as a Determinant of Post-Transplant Survival

BACKGROUND

Decreased peak oxygen consumption during exercise (peak Vo₂) is a well-established prognostic marker for mortality in ambulatory heart failure. After heart transplantation, the utility of peak Vo₂ as a marker of post-transplant survival is not well established.

METHODS AND RESULTS

We performed a retrospective analysis of adult heart transplant recipients at the Hospital of the University of Pennsylvania who underwent cardiopulmonary exercise testing within a year of transplant between the years 2000 to 2011. Using time-to-event models, we analyzed the hazard of mortality over nearly two decades of follow-up as a function of post-transplant percent predicted peak Vo₂ (%Vo₂). A total of 235 patients met inclusion criteria. The median post-transplant %Vo₂ was 49% (IQR 42 to 60). Each standard deviation (±14%) increase in %Vo₂ was associated with a 32% decrease in mortality in adjusted models (HR 0.68, 95% CI 0.53 to 0.87, p = 0.002). A %Vo₂ below 29%, 64% and 88% predicted less than 80% survival at 5, 10, and 15 years, respectively.

CONCLUSIONS

Post-transplant peak Vo₂ is a highly significant prognostic marker for long-term post-transplant survival. It remains to be seen whether decreased peak Vo₂ post-transplant is modifiable as a target to improve post-transplant longevity.

Single-leg cycling to maintain and improve function in healthy and clinical populations

Exercise with reduced muscle mass facilitates greater muscle-specific adaptations than training with larger muscle mass. The smaller active muscle mass can demand a greater portion of cardiac output which allows muscle(s) to perform greater work and subsequently elicit robust physiological adaptations that improve health and fitness. One reduced active muscle mass exercise that can promote greater positive physiological adaptations is single-leg cycling (SLC). Specifically, SLC confines the cycling exercise to a smaller muscle mass resulting in greater limb specific blood flow (i.e., blood flow is no longer "shared" by both legs) which allows the individual to exercise at a greater limb specific intensity or for a longer duration. Numerous reports describing the use of SLC have established cardiovascular and/or metabolic benefits of this exercise modality for healthy adults, athletes, and individuals living with chronic diseases. SLC has served as a valuable research tool for understanding central and peripheral factors to phenomena such as oxygen uptake and exercise tolerance (i.e., V̇O_2peak and V̇O₂ slow component). Together, these examples highlight the breadth of applications of SLC to promote, maintain, and study health. Accordingly, the purpose of this review was to describe: 1) acute physiological responses to SLC, 2) long-term adaptations to SLC in populations ranging from endurance athletes to middle aged adults, to individuals living with chronic disease (COPD, heart failure, organ transplant), and 3) various methods utilized to safely perform SLC. A discussion is also included on clinical application and exercise prescription of SLC for the maintenance and/or improvement of health.

Does Exercise Training Improve Physical Fitness and Health in Adult Liver Transplant Recipients? A Systematic Review and Meta-analysis

BACKGROUND

The impaired physical fitness of end-stage liver disease patients often persists after liver transplantation (LT) and compromises posttransplant recovery. This systematic review and meta-analysis evaluated evidence supporting the potential of exercise training to improve physical fitness and health-related quality of life (HRQOL) after LT.

METHODS

Bibliographic searches identified all randomized controlled trials (RCTs) comparing aerobic and strength training versus usual care after LT. Risk of bias was assessed, and study outcomes measuring physical fitness and HRQOL were extracted. Meta-analysis was performed if at least 3 studies reported on an outcome.

RESULTS

Eight RCTs (n = 334) were identified. Methodological study quality varied and was poorly reported. Meta-analyses showed a trend for favorable effects of exercise on cardiorespiratory fitness (peak oxygen uptake or 6-min walking distance; 6 studies, n = 275; standardized mean difference: 0.23, 95% confidence interval [CI], -0.01 to 0.48) and of strength training either or not combined with aerobic training on muscular fitness (dynamometry-assessed muscle strength or 30-s sit-to-stand test; 3 studies, n = 114; standardized mean difference: 0.34, 95% CI, -0.03 to 0.72). A favorable effect was found for exercise on the Short-Form Health Survey-36 HRQOL physical function subcomponent (3 studies, n = 194; mean difference: 9.1, 95% CI, 0.3-17.8). No exercise-related adverse events were observed.

CONCLUSIONS

RCTs indicate that exercise training in LT recipients is safe, improves physical function aspects of HRQOL, and may benefit cardiorespiratory and muscular fitness. The strength of evidence is, however, limited by the low number of patients and study quality. More adequately powered, high-quality RCTs are warranted.

Disseminating education to solid organ transplant recipients to promote engagement in physical activity

Objective

To evaluate the dissemination of education through a workshop to promote engagement in physical activity (PA) among solid organ transplant (SOT) recipients.

Methods

The in-person workshop consisted of expert-led lectures on topics related to physical activity (day 1) and sports and fitness training with volunteer coaches (day 2). There were separate streams for children/adolescents and adults. RE-AIM (Reach, Efficacy, Adoption, Implementation, and Maintenance) framework was used to evaluate the impact of the workshop. Presenters and participants completed evaluations of the workshop using a 5-point Likert scale. A subgroup of adults completed a self-reported PA questionnaire at baseline and 4-weeks after the workshop.

Results

103 individuals (71 SOT recipients, 32 caregivers) attended the workshop (ages 4 to 71+ years). Sessions were highly rated (median = 5) for both quality and content on both days. There was no significant change (p = 0.16) in PA. However, 56% of SOT recipients reported changing their level of PA.

Conclusion

An educational-workshop with hands-on training was an efficient and well-received method for disseminating awareness about the benefits of PA in SOT recipients.

Innovation

Dissemination of evidence-based knowledge through a novel educational-workshop in a real-world setting has the potential to inform the decisions about PA behavior among SOT recipients.

Patient-reported outcomes evaluation and assessment of facilitators and barriers to physical activity in the Transplantoux aerobic exercise intervention

Background

Transplantoux’s MVT exercise intervention prepares organ transplant recipients to cycle or hike up France’s Mont Ventoux. We aimed to assess (i) MVT’s effects on patient-reported outcomes (PROs) and (ii) perceived barriers and facilitators to physical activity.

Methods

Using a hybrid design, a convenience sample of transplant recipients participating in MVT (n = 47 cycling (TxCYC); n = 18 hiking (TxHIK)), matched control transplant recipients (TxCON, n = 213), and healthy MVT participants (HCON, n = 91) completed surveys to assess physical activity (IPAQ), health-related quality of life (HRQOL; SF-36 and EuroQol VAS), mental health (GHQ-12), and depressive symptomatology, anxiety, and stress (DASS-21) at baseline, then after 3, 6 (Mont Ventoux climb), 9, and 12 months. TxCYC and TxHIK participated in a 6-month intervention of individualized home-based cycling/hiking exercise and a series of supervised group training sessions. Barriers and facilitators to physical activity (Barriers and Motivators Questionnaire) were measured at 12 months.

Results

Regarding PROs, except for reducing TxHIK stress levels, MVT induced no substantial intervention effects. For both TxCYC and TxHIK, between-group comparisons at baseline showed that physical activity, HRQOL, mental health, depressive symptomatology and stress were similar to those of HCON. In contrast, compared to TxCYC, TxHIK, and HCON, physical activity, HRQOL and mental health were lower in TxCON. TxCON also reported greater barriers, lower facilitators, and different priority rankings concerning physical activity barriers and facilitators.

Conclusion

Barely any of the PROs assessed in the present study responded to Transplantoux’s MVT exercise intervention. TxCON reported distinct and unfavorable profiles regarding PROs and barriers and facilitators to physical activity. These findings can assist tailored physical activity intervention development.

Trial registration

Clinical trial notation: The study was approved by the University Hospitals Leuven’s Institutional Review Board (B322201523602).

Clinical Implementation of Different Strategies for Exercise-Based Rehabilitation in Kidney and Liver Transplant Recipients: A Pilot Study

Fundamento:

A doença cardiovascular está entre as principais causas de morte entre pacientes transplantados. Embora esses pacientes possam teoricamente se beneficiar de programas de reabilitação baseada em exercícios (RBE), sua implementação ainda é um desafio.

Objetivo:

Apresentamos nossa experiência inicial em diferentes modos de realização de um programa piloto de RBE em receptores de transplante de rim e fígado.

Métodos:

Trinta e dois pacientes transplantados renais ou hepáticos foram convidados para um programa de RBE de 6 meses realizado na academia do hospital, na academia comunitária ou em casa, de acordo com a preferência do paciente. O nível de significância adotado foi de 5%.

Resultados:

Dez pacientes (31%) não completaram o programa. Entre os 22 que completaram, 7 treinaram na academia do hospital, 7 na academia comunitária e 8 em casa. O efeito geral foi um aumento de 11,4% nos METs máximos (tamanho do efeito de Hedges g = 0,39). O grupo de academia hospitalar teve um aumento nos METs de 25,5% (g = 0,58, tamanho de efeito médio) versus 10% (g = 0,25) e 6,5% (g = 0,20) para os grupos de academia comunitária e em casa, respectivamente. Houve efeito benéfico nas pressões arteriais sistólica e diastólica, maior para os grupos academia hospitalar (g= 0,51 e 0,40) e academia comunitária (g= 0,60 e 1,15) do que para os pacientes treinando em casa (g= 0,07 e 0,10). Nenhum evento adverso significativo foi relatado durante o seguimento.

Conclusão:

Programas de RBE em receptores de transplante de rim e fígado devem ser incentivados, mesmo que sejam realizados fora da academia do hospital, pois são seguros com efeitos positivos na capacidade de exercício e nos fatores de risco cardiovascular.

The Effect of Endurance Training on Pulmonary V˙O2 Kinetics in Solid Organs Transplanted Recipients

Background: We investigated the effects of single (SL-ET) and double leg (DL-ET) high-intensity interval training on O2 deficit (O2Def) and mean response time (MRT) during square-wave moderate-intensity exercise (DL-MOD), and on the amplitude of V˙O2p slow component (SCamp), during heavy intensity exercise (DL-HVY), on 33 patients (heart transplant = 13, kidney transplanted = 11 and liver transplanted = 9). Methods: Patients performed DL incremental step exercise to exhaustion, two DL-MOD tests, and a DL-HVY trial before and after 24 sessions of SL-ET (n = 17) or DL-ET (n = 16). Results: After SL-ET, O2Def, MRT and SCamp decreased by 16.4% ± 13.7 (p = 0.008), by 15.6% ± 13.7 (p = 0.004) and by 35% ± 31 (p = 0.002), respectively. After DL-ET, they dropped by 24.9% ± 16.2 (p < 0.0001), by 25.9% ± 13.6 (p < 0.0001) and by 38% ± 52 (p = 0.0003), respectively. The magnitude of improvement of O2Def, MRT, and SCamp was not significantly different between SL-ET and DL-ET after training. Conclusions: We conclude that SL-ET is as effective as DL-ET if we aim to improve V˙O2p kinetics in transplanted patients and suggest that the slower, V˙O2p kinetics is mainly caused by the impairment of peripherals exchanges likely due to the immunosuppressive medications and disuse.

Metabolic and functional effects of exercise training in diabetic kidney transplant recipients

BACKGROUND

Physical activity levels are significantly lower in kidney transplant (KT) recipients compared to the general population. The effects of exercise training in KT recipients with diabetes mellitus remain unclear, and so little is known about the role of increased exercise on cardiovascular risk and metabolic profile of KT patients.

AIM

To investigate the effects of a 6-mo home-based exercise training program on functional capacity, glucose levels and lipid profile of diabetic KT patients.

METHODS

In total, 21 type II diabetic KT recipients were randomly assigned into two groups: Exercise (n = 11, aged 52.9 ± 10.1 years) and control (n = 10, aged 53.01 ± 9.5 years). All participants at baseline and the end of the study underwent biochemical tests for fasting plasma glucose levels, glycated hemoglobin and lipid profile and cardiopulmonary exercise testing for maximum oxygen uptake [(VO₂)_peak] estimation. The exercise group followed a 6-mo supervised home-based aerobic and progressive resistance exercise program of moderate intensity 3 times per week, while the control group continued to receive usual care.

RESULTS

At the end of the 6-mo study, the exercise group had significantly lower values in fasting plasma glucose by 13.4% (from 120.6 ± 28.9 mg/dL to 104.8 ± 21.9 mg/dL, P = 0.01), glycated hemoglobin by 1.5% (from 6.7% ± 0.4 to 6.6% ± 0.4, P = 0.01) and triglycerides by 8.5% (from 164.7 ± 14.8 mg/dL to 150.8 ± 11.6 mg/dL, P < 0.05) and higher values in high-density lipoprotein by 10.2% (from 51.4 ± 8.8 mg/dL to 57.2 ± 8.7 mg/dL, P < 0.05) and (VO₂)_peak by 4.7% (from 22.7 ± 3.3 to 23.8 ± 4.2, P = 0.02) than the control group. There were statistically significant differences between the two groups at the end of the study for fasting plasma glucose (decreased by 9.6%, P < 0.05), triglycerides (decreased by 4.5%, P = 0.04) and (VO₂)_peak (increased by 4.4%, P = 0.01). Finally, after training, there was a moderate, positive linear relationship between (VO₂)_peak and glycated hemoglobin in the exercise group (r = 0.408, P = 0.03).

CONCLUSION

The results demonstrated that a 6-mo home-based mixed type exercise training program can improve the functional capacity, levels of glucose and lipid profile of diabetic KT recipients.

Inclusion of Exercise Prescription in Solid Organ Transplant in Physical Therapy Curricula Across Canadian Universities: A National Survey

Purpose : This study evaluated the extent of education about exercise prescription for patients with solid organ transplant (SOT) provided in physical therapy (PT) entry-level programmes across Canadian universities. The nature (content being taught), delivery (modes used to disseminate information), time dedicated to the topic, and opinions of educators were explored. Method : A cross-sectional survey was emailed to 36 educators at Canadian universities. The survey questions related to the nature, delivery, and time dedicated to SOT exercise prescription, and the opinions of educators. Results : The response rate was 93%. Educators reported that lung and heart transplantation were taught the most, followed by kidney and liver, with little to no emphasis on pancreas transplants. This material was mainly taught at the graduate level and as part of cardiopulmonary courses with minimal emphasis on practical skills. Aerobic exercise is the main exercise prescription being taught. The main barrier to offering more SOT prescription education experienced by educators was the lack of available class time. Conclusions : SOT exercise prescription is not extensively covered in PT curricula and does not include all organ groups to the same extent. Students have few practical opportunities, which are important to gain the abilities and confidence to treat this population. The development of a continuing education course could promote greater knowledge.

Characteristics of transplant athletes competing at national and international transplant games

Objective

To describe the characteristics of athletes with solid-organ transplants (TxA) attending the British and World Transplant Games.

Methods

220 TxA completed an online survey to explore transplant history, medications, training advice and support and limitations to training.

Results

TxA were predominantly caucasian, male, kidney recipients in their mid-forties and approximately 11 years post-transplant. The majority of TxA took some form of medication (immunosuppressants 88%, steroids 47%, antihypertensives 47%, statins 28%, antiplatelets 26%, antibiotics/antivirals/antifungals 20%). Stem cell recipients were least likely to require medication. Post-transplant complications were experienced by 40% of TxA, with 53% of these being rejection. Although over half the participants (57%) initially received exercise or training advice post-transplant, only 34% of these received this from their consultants or immediate medical team. Only 1% had been specifically directed towards transplant sport. Half of the TxA (53%) perceived there were limitations preventing them from performing at their potential, 45% considered they did not recover from training as well as non-TxA while 29% felt they trained equally to non-Tx’s. Only 6% considered medication impaired training. TxA competed for a range of reasons from social and health benefits to winning medals.

Conclusions

TxA compete at the British and World Transplant Games for a diverse range of reasons. Athletes manage a range of medications with a range of exercise and health experiences pre-transplant. TxA face a lack of both general and specific exercise training and recovery guidance. The individuality of each TxA‘s background should be considered and is likely reflected in their exercise capacity and goals.

Criterion Validity and Test-Retest Reliability of a Modified Version of the International Physical Activity Questionnaire–Short Form (IPAQ-SF) in Kidney Transplant Recipients

Introduction

Accelerometry, the clinically valued standard of physical activity monitoring, has limited acceptance in transplantation rehabilitation; therefore, the International Physical Activity Questionnaire (IPAQ) self-report instrument is widely used. However, while the IPAQ's repeatability is good, its criterion validity is unsatisfactory. We hypothesized that adding a concise oral introduction would help overcome this shortfall.

Materials and Methods

This is a secondary analysis of a RCT in a sample of kidney transplant recipients that underwent observational follow-up. We assessed criterion validity of our modified version of the four-item IPAQ–Short Form (mIPAQ–SF) via Pearson, and test-retest reliability via intraclass correlation coefficients. The main difference in the new version is an oral pre-measurement introduction to the questionnaire's concepts. We compared our results with those of published studies.

Results

Post-kidney-transplantation data of 92 patients were analyzed. Across the four IPAQ-SF/mIPAQ–SF items, values of correlations between mIPAQ-SF responses and accelerometry records ranged from 0.07 (min in vigorous activity) to 0.35 (min in moderate activity) for criterion validity, and from 0.19 (days with moderate activity) to 0.58 (min in moderate activity) for test-retest reliability.

Discussion

Regarding moderate-to-vigorous physical activity, mIPAQ-SF self-reports' correlations to accelerometry records improved considerably on those of the IPAQ-SF (r = 0.18 vs. r = 0.33), i.e., improved criterion validity. We therefore conclude that a pre-measurement oral explanation of key IPAQ-SF/mIPAQ concepts enhances criterion validity regarding self-reported moderate-to-vigorous physical activity.

Effect of small vs large muscle mass endurance training on maximal oxygen uptake in organ transplanted recipients

Maximal oxygen consumption (V̇O_2max) is impaired in heart (HTx), kidney (KTx), and liver (LTx) transplanted recipients and the contribution of the cardiovascular, central, and peripheral (muscular) factors in affecting V̇O_2max improvement after endurance training (ET) has never been quantified in these patients. ET protocols involving single leg cycling (SL) elicit larger improvements of the peripheral factors affecting O₂ diffusion and utilization than the double leg (DL) cycling ET. Therefore, this study aimed to compare the effects of SL-ET vs DL-ET on V̇O_2max. We determined the DL-V̇O_2max and maximal cardiac output before and after 24 SL-ET vs DL-ET sessions on 33 patients (HTx = 13, KTx = 11 and LTx = 9). The DL-V̇O_2max increased by 13.8% ± 8.7 (p < 0.001) following the SL-ET, due to a larger maximal O₂ systemic extraction; meanwhile, V̇O_2max in DL-ET increased by 18.6% ± 12.7 (p < 0.001) because of concomitant central and peripheral adaptations. We speculate that in transplanted recipients, SL-ET is as effective as DL-ET to improve V̇O_2max and that the impaired peripheral O₂ extraction and/or utilization play an important role in limiting V̇O_2max in these types of patients. Novelty: SL-ET increases V̇O_2max in transplanted recipients because of improved peripheral O₂ extraction and/or utilization. SL-ET is as successful as DL-ET to improve the cardiorespiratory fitness in transplanted recipients. The model of V̇O_2max limitation indicates the peripheral factors as a remarkable limitation to the V̇O_2max in these patients.

The effects of exercise training in adult solid organ transplant recipients: A systematic review and meta-analysis

Reduced exercise capacity can predispose solid organ transplant (SOT) recipients to higher risk of diabetes, cardiovascular complications, and mortality and impact their quality of life. This systematic review and meta-analysis investigated the effects of exercise training (versus no training) in adult SOT recipients. We conducted an electronic search of randomized controlled trials reporting on exercise interventions in SOT recipients. Primary outcomes were exercise capacity, quadriceps muscle strength, and health-related quality of life (HRQoL). Twenty-nine articles met the inclusion criteria. In 24 studies, there were either high risk of bias or some concerns about the potential risk of bias. There was an increase in exercise capacity (VO₂ peak) (SMD: 0.40; 95%CI 0.22-0.57; P = 0.0) and quadriceps muscle strength (SMD: 0.38; 95%CI 0.16-0.60; P = 0.001) in the exercise vs control groups. There were also improvements in several domains of the SF-36. Diastolic blood pressure improved in the exercise group compared to controls (SMD: -0.22; 95%CI -0.41-0.03; P = 0.02). Despite the considerable variation in exercise training characteristics and high risk of bias in the included studies, exercise training improved maximal exercise capacity, quadriceps muscle strength, HRQoL, and diastolic blood pressure and should be an essential part of the post-transplant care.

Metabolic Consequences of Solid Organ Transplantation

Metabolic complications affect over 50% of solid organ transplant recipients. These include posttransplant diabetes, nonalcoholic fatty liver disease, dyslipidemia, and obesity. Preexisting metabolic disease is further exacerbated with immunosuppression and posttransplant weight gain. Patients transition from a state of cachexia induced by end-organ disease to a pro-anabolic state after transplant due to weight gain, sedentary lifestyle, and suboptimal dietary habits in the setting of immunosuppression. Specific immunosuppressants have different metabolic effects, although all the foundation/maintenance immunosuppressants (calcineurin inhibitors, mTOR inhibitors) increase the risk of metabolic disease. In this comprehensive review, we summarize the emerging knowledge of the molecular pathogenesis of these different metabolic complications, and the potential genetic contribution (recipient +/- donor) to these conditions. These metabolic complications impact both graft and patient survival, particularly increasing the risk of cardiovascular and cancer-associated mortality. The current evidence for prevention and therapeutic management of posttransplant metabolic conditions is provided while highlighting gaps for future avenues in translational research.

Exercise training in patients after kidney transplantation

Kidney transplantation is the treatment of choice for patients with end-stage renal disease. Next to the risk of allograft failure, major obstacles for disease-free survival after kidney transplantation include a higher incidence of cancer, infection and cardiovascular events. Risk factors for adverse clinical outcomes include pre-existent comorbidities, the introduction of an immunodeficient status and (lack of) lifestyle changes after transplantation. Indeed, physical inactivity and poor physical fitness are important targets to address in order to improve clinical outcomes after kidney transplantation. This review summarizes the current evidence on exercise training after kidney transplantation, derived from randomized controlled trials. As much as possible, results are discussed in the perspective of the Standardized Outcomes in Nephrology-Transplantation core outcomes, which were recently described as critically important outcome domains for trials in kidney transplant recipients.

Characteristics and Motivation of Solid Organ Transplant Recipients Attending the Canadian Transplant Games

BACKGROUND

The Canadian Transplant games ("Games") were created to increase awareness of organ donation and highlight the importance of staying active and healthy post-transplant. It is unclear what motivates solid organ transplant (SOT) recipients to participate and whether the games serve as an incentive for SOT recipients to increase their physical activity (PA) levels.

OBJECTIVES

1. To describe the characteristics of participants from past games and their motivation for attending and 2. to determine whether there was an interest in participating in goal-based, pre-games exercise training programs.

METHODS

A web-based questionnaire was sent to adult SOT recipients who were members of the Canadian Transplant Association. The survey included questions about why participants attended, their PA levels, and their interest in a pre-games training program.

RESULTS

Of the 157 participants, more were male than female; the 35-54-year-old age group was the most common; and 62% of respondents received a liver or kidney transplant. The most common reasons for participating in the games were to showcase health post-transplant, promote awareness of organ donation, sports competition, and social reasons. Sixty-five percent of respondents reported that they would be interested in an exercise program to be more physically prepared for the competition.

CONCLUSION

Pre-games training programs could be developed to motivate participation and help participants achieve higher training intensities and foster social interaction. Directing resources to individuals who do not attend the games and to those who are not physically active should be considered.

Exercise and physical activity in cirrhosis: opportunities or perils

Reduced exercise capacity and impaired physical performance are observed in nearly all patients with liver cirrhosis. Physical activity and exercise are physiological anabolic stimuli that can reverse dysregulated protein homeostasis or proteostasis and potentially increase muscle mass and contractile function in healthy subjects. Cirrhosis is a state of anabolic resistance, and unlike the beneficial responses to exercise reported in physiological states, there are few systematic studies evaluating the response to exercise in cirrhosis. Hyperammonemia is a mediator of the liver-muscle axis with net skeletal muscle ammonia uptake in cirrhosis causing signaling perturbations, mitochondrial dysfunction with decreased ATP content, modifications of contractile proteins, and impaired ribosomal function, all of which contribute to anabolic resistance in cirrhosis and have the potential to impair the beneficial responses to exercise. English language-publications in peer-reviewed journals that specifically evaluated the impact of exercise in cirrhosis were reviewed. Most studies evaluated responses to endurance exercise, and readouts included peak or maximum oxygen utilization, grip strength, and functional capacity. Endurance exercise for up to 12 wk is clinically tolerated in well-compensated cirrhosis. Data on the safety of resistance exercise are conflicting. Nutritional supplements enhance the benefits of exercise in healthy subjects but have not been evaluated in cirrhosis. Whether the beneficial physiological responses with endurance exercise and increase in muscle mass with resistance exercise that occur in healthy subjects also occur in cirrhotics is not known. Specific organ-system responses, changes in body composition, or improved long-term clinical outcomes with exercise in cirrhosis need evaluation.

Perceptions towards physical activity in adult lung transplant recipients with cystic fibrosis

Background

Barriers and motives towards physical activity (PA) in lung transplant (LTx) recipients with cystic fibrosis (CF) are largely unknown. We aimed to explore perceptions towards PA in LTx recipients with CF to better understand individuals’ needs and preferences.

Methods

Participants completed an online survey at two Swiss LTx and one follow-up shared care centre between June and December 2018.

Results

One hundred and eleven individuals completed the survey (87.4% response rate). Overall, survey participants perceive PA as important for their daily life and health. Perceived motives of PA were improving muscle strength, endurance and quality of life (QoL), to feel better, fun, to achieve personal goals and having more energy for everyday life. Fatigue was the most common perceived barrier to PA and associated with poorer QoL (r = -0.43, p<0.001) and health status (r = -0.31, p = 0.001). Participants with lung allograft dysfunction (LAD, n = 20) reported lower habitual PA (p = 0.009) and health status (p = 0.011), and rated shortness of breath, bad weather and concerns regarding lung rejection higher than those without LAD (all p<0.05). When we asked how an optimal training programme should look like, the majority would prefer individual, non-supervised (60%), outdoor (77%), endurance training (90%), once or twice a week (47%) for 40–60 minutes (48%). Only a minority of patients (14%) would be willing to use exercise applications for their home-based training.

Conclusions

LTx recipients with CF value PA as important for their health. People with CF should be encouraged individually by their multidisciplinary transplant team to implement PA in their daily life, potential barriers should be identified and addressed. Overall, knowledge on perceived barriers and motives for PA should be considered in the development of future patient-centred PA programmes.

Inactivity and exercise training differentially regulate abundance of Na+-K+-ATPase in human skeletal muscle

Physical inactivity is a global health risk that can be addressed through application of exercise training suitable for an individual's health and age. People's willingness to participate in physical activity is often limited by an initially poor physical capability and early onset of fatigue. One factor associated with muscle fatigue during intense contractions is an inexcitability of skeletal muscle cells, reflecting impaired transmembrane Na⁺/K⁺ exchange and membrane depolarization, which are regulated via the transmembranous protein Na⁺-K⁺-ATPase (NKA). This short review focuses on the plasticity of NKA in skeletal muscle in humans after periods of altered usage, exploring NKA upregulation with exercise training and downregulation with physical inactivity. In human skeletal muscle, the NKA content quantified by [³H]ouabain binding site content shows robust, yet tightly constrained, upregulation of 8-22% with physical training, across a broad range of exercise training types. Muscle NKA content in humans undergoes extensive downregulation with injury that involves substantial muscular inactivity. Surprisingly, however, no reduction in NKA content was found in the single study that investigated short-term disuse. Despite clear findings that exercise training and injury modulate NKA content, the adaptability of the individual NKA isoforms in muscle (α_1-3 and β_1-3) and of the accessory and regulatory protein FXYD1 are surprisingly inconsistent across studies, for exercise training as well as for injury/disuse. Potential reasons for this are explored. Finally, we provide suggestions for future studies to provide greater understanding of NKA regulation during exercise training and inactivity in humans.

ESPEN guideline on clinical nutrition in liver disease

This update of evidence-based guidelines (GL) aims to translate current evidence and expert opinion into recommendations for multidisciplinary teams responsible for the optimal nutritional and metabolic management of adult patients with liver disease. The GL was commissioned and financially supported by ESPEN. Members of the guideline group were selected by ESPEN. We searched for meta-analyses, systematic reviews and single clinical trials based on clinical questions according to the PICO format. The evidence was evaluated and used to develop clinical recommendations implementing the SIGN method. A total of 85 recommendations were made for the nutritional and metabolic management of patients with acute liver failure, severe alcoholic steatohepatitis, non-alcoholic fatty liver disease, liver cirrhosis, liver surgery and transplantation as well as nutrition associated liver injury distinct from fatty liver disease. The recommendations are preceded by statements covering current knowledge of the underlying pathophysiology and pathobiochemistry as well as pertinent methods for the assessment of nutritional status and body composition.

Physical Activity, Sedentary Time, and Associated Factors in Recipients of Solid-Organ Transplantation

BACKGROUND

Short-term survival after solid-organ transplantation has substantially improved, and the focus has shifted to long-term survival, including the role of physical activity (PA). Knowledge about PA and sedentary time in recipients of solid-organ transplantation is limited, and identification of the levels and associated factors is necessary for intervention development.

OBJECTIVE

The objectives of this study were to investigate the level of PA and sedentary time in recipients of solid-organ transplantation and to identify factors associated with these behaviors.

DESIGN

The design consisted of a cross-sectional survey.

METHODS

Questionnaires on PA level, sedentary time, and potential associated factors were used for recipients of solid-organ transplantation (kidney, liver, lung, and heart [N = 656]). Multiple regression analyses with a variable selection procedure were used.

RESULTS

Fewer than 60% of the recipients fulfilled the PA guideline. Factors significantly associated with a lower level of PA included being a woman, younger age (nonlinear), not actively working or being retired, physical limitations, and low expectations and self-confidence. Factors significantly associated with less sedentary time included exercise self-efficacy and not actively working or being retired. Significantly associated with more sedentary time were a high education level, fear of negative effects, physical limitations, and the motivator "health and physical outcomes." The type of transplantation did not significantly influence either of the outcome measures.

LIMITATIONS

The design did not allow for causal inferences to be made. The studied associated factors were limited to individual and interpersonal factors. Self-reported measures of PA and sedentary time were used.

CONCLUSIONS

In intervention development directed at increasing the level of PA and reducing sedentary time in recipients of solid-organ transplantation, attention should be paid to physical limitations, fear of negative effects, low expectations and self-confidence, health and physical outcomes, and exercise self-efficacy.

High altitude trekking after lung transplantation: a prospective study using lung ultrasound to detect comets tails for interstitial pulmonary edema in lung transplant recipients and healthy volunteers

The intensity of physical activity which can be tolerated after lung transplantation and the tolerance to prolonged exercise at high altitude are poorly investigated. Lung ultrasound comet tails have been used in the diagnosis of interstitial pulmonary edema and high pulmonary altitude edema. The aim was to assess the number of lung ultrasound comet tails and to monitor changes in the optic nerve sheath diameter (ONSD) during a climb to the top of Mount Kilimanjaro in 10 lung transplant recipients and 10 healthy controls at three different altitude levels: 1360, 3505, 4900 m. Lung transplant recipients showed a constant increase in comet tail scores with altitude, whereas control subjects only showed an increase at the highest measurement point. Differences between groups (transplant versus control) reached significance only after the first ascend: 0.9 (95% CI: -0.41; 2.21) vs. 0.1 (95% CI: -0.12; 0.32) (P = 0.2; 1360 m), 2.33 (95% CI: 0.64; 4.02) vs. 0.3 (95% CI: -0.18; 0.78) (P = 0.04; 3505 m), and 4.11 (95% CI: 0.13; 0.34) vs. 2.9 (95% CI: 0.49; 5.31) (P = 0.15; 4900 m); ONSD increased significantly in both groups from 3.53 (95% CI: 0.34; 0.66) at 1360 m to 4.11 (95% CI: 0.36; 0.71) at 4900 m (P < 0.05). Lungs of transplant recipients are able to adapt to altitude and capable of performing prolonged exercise at high altitude after slow ascend.

Solid Organ Transplant Recipients' Opinions of Pre- and Post-Transplant Supervised Exercise Programmes: A Brief Report

Purpose: Access to pre- and post-transplant supervised exercise programmes in Canada is not consistent across organ types. The opinions of solid organ transplant (SOT) recipients can contribute to the discussion among stakeholders regarding increasing the availability of supervised exercise programmes. The objective of the study was to determine Canadian SOT recipients' opinions of pre- and post-transplant supervised exercise programmes and the factors that influenced their participation. Method: An Internet-based questionnaire was distributed to members of the Canadian Transplant Association. It was part of a larger survey and examined seven items related to accessibility to, and opinion of, supervised exercise programmes. Results: A total of 35% (n=39) of respondents had attended a pre-transplant exercise programme, and 54% (n=61) had attended a post-transplant exercise programme. The majority of participants believed that a supervised exercise programme was beneficial to health and well-being. Perception of benefits, a physician's recommendation, and health status and symptoms were key influencing factors in the decision of whether to attend a pre- or post-transplant exercise programme. Conclusion: SOT recipients had positive opinions of supervised exercise programmes despite unequal access among organ groups. Some key influencing factors (e.g., a physician's recommendation) are modifiable and should be taken into consideration to encourage participation in such programmes.

Evolution of body weight parameters up to 3 years after solid organ transplantation: The prospective Swiss Transplant Cohort Study

Obesity and weight gain are serious concerns after solid organ transplantation (Tx); however, no unbiased comparison regarding body weight parameter evolution across organ groups has yet been performed. Using data from the prospective nationwide Swiss Transplant Cohort Study, we compared the evolution of weight parameters up to 3 years post-Tx in 1359 adult kidney (58.3%), liver (21.7%), lung (11.6%), and heart (8.4%) recipients transplanted between May 2008 and May 2012. Changes in mean weight and body mass index (BMI) category were compared to reference values from 6 months post-Tx. At 3 years post-Tx, compared to other organ groups, liver Tx recipients showed the greatest weight gain (mean 4.8±10.4 kg), 57.4% gained >5% body weight, and they had the highest incidence of obesity (38.1%). After 3 years, based on their BMI categories at 6 months, normal weight and obese liver Tx patients, as well as underweight kidney, lung and heart Tx patients had the highest weight gains. Judged against international Tx patient data, the majority of our Swiss Tx recipients' experienced lower post-Tx weight gain. However, our findings show weight gain pattern differences, both within and across organ Tx groups that call for preventive measures.

Outcomes in randomized controlled trials of exercise interventions in solid organ transplant

AIM

To identify the outcome measures that have been used in randomized controlled trials (RCTs) of exercise training in solid organ transplant (SOT) recipients and to link these outcomes to the International Classification of Functioning, Disability and Health (ICF) framework.

METHODS

Electronic literature searches of MEDLINE, EMBASE, CINAHL, Cochrane, Scopus, and Web of Science were performed. We sought RCTs that investigated the effect of exercise training in SOT recipients. Reference lists of all eligible publications were searched for other appropriate studies not identified by the electronic search. A complete list of outcome measures used in the RCTs was generated and each of these was linked to an ICF category.

RESULTS

Four hundred and thirteen articles were retrieved, of which 35 met our inclusion criteria. The studies included were designed to compare the effects of exercise training programs to usual care or to another exercise training program and reported on recipients of heart (n = 21), kidney (n = 9), lung (n = 3) or liver (n = 2) transplant. Of the 126 outcome measures identified, 62 were used as primary outcome measures. The most commonly occurring primary outcomes were aerobic capacity using the peak VO₂ (n = 13), quality of life using the short-form-36 (n = 8), and muscle strength (n = 7). These outcome measures were linked to 113 ICF categories and the majority of outcomes fall into the body function domain (n = 93).

CONCLUSION

There is little standardization in outcome measures used in RCTs of exercise interventions in SOT recipients. The ICF framework can be used to select a core set of outcomes that cross all domains of ICF and that would be appropriate to all SOT recipients.

Sarcopenia from mechanism to diagnosis and treatment in liver disease

Sarcopenia or loss of skeletal muscle mass is the major component of malnutrition and is a frequent complication in cirrhosis that adversely affects clinical outcomes. These include survival, quality of life, development of other complications and post liver transplantation survival. Radiological image analysis is currently utilized to diagnose sarcopenia in cirrhosis. Nutrient supplementation and physical activity are used to counter sarcopenia but have not been consistently effective because the underlying molecular and metabolic abnormalities persist or are not influenced by these treatments. Even though alterations in food intake, hypermetabolism, alterations in amino acid profiles, endotoxemia, accelerated starvation and decreased mobility may all contribute to sarcopenia in cirrhosis, hyperammonemia has recently gained attention as a possible mediator of the liver-muscle axis. Increased muscle ammonia causes: cataplerosis of α-ketoglutarate, increased transport of leucine in exchange for glutamine, impaired signaling by leucine, increased expression of myostatin (a transforming growth factor beta superfamily member) and an increased phosphorylation of eukaryotic initiation factor 2α. In addition, mitochondrial dysfunction, increased reactive oxygen species that decrease protein synthesis and increased autophagy mediated proteolysis, also play a role. These molecular and metabolic alterations may contribute to the anabolic resistance and inadequate response to nutrient supplementation in cirrhosis. Central and skeletal muscle fatigue contributes to impaired exercise capacity and responses. Use of proteins with low ammoniagenic potential, leucine enriched amino acid supplementation, long-term ammonia lowering strategies and a combination of resistance and endurance exercise to increase muscle mass and function may target the molecular abnormalities in the muscle. Strategies targeting endotoxemia and the gut microbiome need further evaluation.

Physical rehabilitation for lung transplant candidates and recipients: An evidence-informed clinical approach

Physical rehabilitation of lung transplant candidates and recipients plays an important in optimizing physical function prior to transplant and facilitating recovery of function post-transplant. As medical and surgical interventions in lung transplantation have evolved over time, there has been a demographic shift of individuals undergoing lung transplantation including older individuals, those with multiple co-morbidites, and candidates with respiratory failure requiring bridging to transplantation. These changes have an impact on the rehabilitation needs of lung transplant candidates and recipients. This review provides a practical approach to rehabilitation based on research and clinical practice at our transplant centre. It focuses on functional assessment and exercise prescription during an uncomplicated and complicated clinical course in the pre-transplant, early and late post-transplant periods. The target audience includes clinicians involved in pre- and post-transplant patient care and rehabilitation researchers.

Perceived Barriers to and Facilitators of Physical Activity in Recipients of Solid Organ Transplantation, a Qualitative Study

Background

Sufficient physical activity is important for solid organ transplant recipients (heart, lung, liver, kidney). However, recipients do not meet the recommended amount or required type of physical activity. The perceived barriers to and facilitators of physical activity in this population are largely unknown.

Methods

Semi-structured in depth interviews were conducted with solid organ transplant recipients in order to explore experienced barriers and facilitators. Qualitative methodology with thematic line-by-line analysis was used for analysis, and derived themes were classified into personal and environmental factors.

Results

The most important indicated barriers were physical limitations, insufficient energy level, fear, and comorbidities. The most frequently mentioned facilitators included motivation, coping, consequences of (in)activity, routine/habit, goals/goal priority, and responsibility for the transplanted organ. Neutral factors acting as a barrier or facilitator were self-efficacy and expertise of personnel. A comparison of barriers and facilitators between transplant recipient groups yielded no overt differences.

Conclusion

Several personal and environmental factors were indicated that should be considered in intervention development to increase physical activity behavior in solid organ transplant recipients.

Travel to High Altitude Following Solid Organ Transplantation

Luks, Andrew M. Clinician's corner: travel to high altitude following solid organ transplantation. High Alt Med Biol. 17:147-156, 2016.-As they regain active lifestyles following successful organ transplantation, transplant recipients may travel to high altitude for a variety of activities, including skiing, climbing, and trekking. This review is intended to provide information for medical providers who may encounter transplant patients seeking advice before planned high altitude travel or care for medical issues that develop during the actual sojourn. There is currently limited information in the literature about outcomes during high-altitude travel following solid organ transplantation, but the available evidence suggests that the physiologic responses to hypobaric hypoxia are comparable to those seen in nontransplanted individuals and well-selected transplant recipients with no evidence of organ rejection can tolerate ascents as high as 6200 m. All transplant recipients planning high-altitude travel should undergo pretravel assessment and counseling with an emphasis on the recognition, prevention, and treatment of altitude illness, as well as the importance of preventing infection and limiting sun exposure. Transplant recipients can use the standard medications for altitude illness prophylaxis and treatment, but the choice and dose of medication should take into account the patient's preexisting medication regimen and current renal function. With careful attention to these and other details, the healthy transplant recipient can safely experience the rewards of traveling in the mountains.

Tolerance of Organ Transplant Recipients to Physical Activity during a High-Altitude Expedition: Climbing Mount Kilimanjaro

BACKGROUND

It is generally unknown to what extent organ transplant recipients can be physically challenged. During an expedition to Mount Kilimanjaro, the tolerance for strenuous physical activity and high-altitude of organ transplant recipients after various types of transplantation was compared to non-transplanted controls.

METHODS

Twelve organ transplant recipients were selected to participate (2 heart-, 2 lung-, 2 kidney-, 4 liver-, 1 allogeneic stem cell- and 1 small bowel-transplantation). Controls comprised the members of the medical team and accompanying family members (n = 14). During the climb, cardiopulmonary parameters and symptoms of acute mountain sickness were recorded twice daily. Capillary blood analyses were performed three times during the climb and once following return.

RESULTS

Eleven of the transplant participants and all controls began the final ascent from 4700 meters and reached over 5000 meters. Eight transplant participants (73%) and thirteen controls (93%) reached the summit (5895m). Cardiopulmonary parameters and altitude sickness scores demonstrated no differences between transplant participants and controls. Signs of hyperventilation were more pronounced in transplant participants and adaptation to high-altitude was less effective, which was related to a decreased renal function. This resulted in reduced metabolic compensation.

CONCLUSION

Overall, tolerance to strenuous physical activity and feasibility of a high-altitude expedition in carefully selected organ transplant recipients is comparable to non-transplanted controls.

Exercise training in chronic heart failure: improving skeletal muscle O2 transport and utilization

Chronic heart failure (CHF) impairs critical structural and functional components of the O2 transport pathway resulting in exercise intolerance and, consequently, reduced quality of life. In contrast, exercise training is capable of combating many of the CHF-induced impairments and enhancing the matching between skeletal muscle O2 delivery and utilization (Q̇mO2 and V̇mO2 , respectively). The Q̇mO2 /V̇mO2 ratio determines the microvascular O2 partial pressure (PmvO2 ), which represents the ultimate force driving blood-myocyte O2 flux (see Fig. 1). Improvements in perfusive and diffusive O2 conductances are essential to support faster rates of oxidative phosphorylation (reflected as faster V̇mO2 kinetics during transitions in metabolic demand) and reduce the reliance on anaerobic glycolysis and utilization of finite energy sources (thus lowering the magnitude of the O2 deficit) in trained CHF muscle. These adaptations contribute to attenuated muscle metabolic perturbations (e.g., changes in [PCr], [Cr], [ADP], and pH) and improved physical capacity (i.e., elevated critical power and maximal V̇mO2 ). Preservation of such plasticity in response to exercise training is crucial considering the dominant role of skeletal muscle dysfunction in the pathophysiology and increased morbidity/mortality of the CHF patient. This brief review focuses on the mechanistic bases for improved Q̇mO2 /V̇mO2 matching (and enhanced PmvO2 ) with exercise training in CHF with both preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). Specifically, O2 convection within the skeletal muscle microcirculation, O2 diffusion from the red blood cell to the mitochondria, and muscle metabolic control are particularly susceptive to exercise training adaptations in CHF. Alternatives to traditional whole body endurance exercise training programs such as small muscle mass and inspiratory muscle training, pharmacological treatment (e.g., sildenafil and pentoxifylline), and dietary nitrate supplementation are also presented in light of their therapeutic potential. Adaptations within the skeletal muscle O2 transport and utilization system underlie improvements in physical capacity and quality of life in CHF and thus take center stage in the therapeutic management of these patients.

Rehabilitation in Patients before and after Lung Transplantation

Lung transplantation is an established treatment for patients with end-stage lung disease. It has been observed that despite near-normal lung function, exercise intolerance and reductions in quality of life (QOL) often persist up to years after transplantation. Several modifiable pre- and posttransplant factors are known to contribute to these persisting impairments. Physiological changes associated with severe and chronic lung disease, limb muscle dysfunction, inactivity/deconditioning, and nutritional depletion can affect exercise capacity and physical functioning in candidates for lung transplantation. After transplantation, extended hospital and intensive care unit stay, prolonged sedentary time, persisting inactivity, immunosuppressant medications and episodes of organ rejection may all impact lung recipients' recovery. Available evidence will be reviewed and content will be proposed (both evidence and experience based) for rehabilitation interventions prior to transplantation, during hospitalization after transplantation, and in both the immediate (≤12 months after hospital discharge) and long-term (>12 months after hospital discharge) posttransplant phase. Outpatient rehabilitation programs including supervised exercise training have been shown to be effective in improving limb muscle dysfunction, exercise capacity, and QOL both before and after transplantation if offered appropriately. Unmet research needs included the absence of sufficiently powered randomized controlled trials measuring the effects of rehabilitation interventions on crucial long-term outcomes such as sustained improvements in QOL, participation in daily activity, survival, incidence of morbidities and cost-effectiveness. Remotely monitored (telehealth) home-based exercise or pedometer-based walking interventions might be interesting alternatives to supervised outpatient rehabilitation interventions in the long-term posttransplant phase and warrant further investigation.

Physical activity levels early after lung transplantation

BACKGROUND

Little is known of the early changes in physical activity after lung transplantation.

OBJECTIVES

The purposes of this study were: (1) to describe physical activity levels in patients up to 6 months following lung transplantation and (2) to explore predictors of the change in physical activity in that population.

DESIGN

This was a prospective cohort study.

METHODS

Physical activity (daily steps and time spent in moderate-intensity activity) was measured using an accelerometer before and after transplantation (at hospital discharge, 3 months, and 6 months). Additional functional measurements included submaximal exercise capacity (measured with the 6-Minute Walk Test), quadriceps muscle torque, and health-related quality of life (measured with the Medical Outcomes Study 36-Item Short-Form Health Survey 36 [SF-36] and the St George's Respiratory Questionnaire).

RESULTS

Thirty-six lung transplant recipients (18 men, 18 women; mean age=49 years, SD=14) completed posttransplant measurements. Before transplant, daily steps were less than a third of the general population. By 3 months posttransplant, the largest improvement in physical activity had occurred, and level of daily steps reached 55% of the general population. The change in daily steps (pretransplant to 3 months posttransplant) was inversely correlated with pretransplant 6-minute walk distance (r=-.48, P=.007), daily steps (r=-.36, P=.05), and SF-36 physical functioning (SF-36 PF) score (r=-.59, P=.0005). The SF-36 PF was a significant predictor of the change in physical activity, accounting for 35% of the variation in change in daily steps.

LIMITATIONS

Only individuals who were ambulatory prior to transplant and discharged from the hospital in less than 3 months were included in the study.

CONCLUSIONS

Physical activity levels improve following lung transplantation, particularly in individuals with low self-reported physical functioning. However, the majority of lung transplant recipients remain sedentary between 3 to 6 months following transplant. The role of exercise training, education, and counseling in further improving physical activity levels in lung transplant recipients should be further explored.

Meeting report: consensus recommendations for a research agenda in exercise in solid organ transplantation

With improved survival rates in solid organ transplantation there has been an increased focus on long-term outcomes following transplant, including physical function, health-related quality-of-life and cardiovascular mortality. Exercise training has the potential to affect these outcomes, however, research on the optimal timing, type, dose of exercise, mode of delivery and relevant outcomes is limited. This article provides a summary of a 2-day meeting held in April 2013 (Toronto, Canada) in which a multi-disciplinary group of clinicians, researchers, administrators and patient representatives engaged in knowledge exchange and discussion of key issues in exercise in solid organ transplant (SOT). The outcomes from the meeting were the development of top research priorities and a research agenda for exercise in SOT, which included the need for larger scale, multi-center intervention studies, development of standardized outcomes for physical function and surrogate measures for clinical trials, examining novel modes of exercise delivery and novel outcomes from exercise training studies such as immunity, infection, cognition and economic outcomes. The development and dissemination of "expert consensus guidelines," synthesizing both the best available evidence and expert opinion was prioritized as a key step toward improving program delivery.

Treatment to improve nutrition and functional capacity evaluation in liver transplant candidates

OPINION STATEMENT

Liver transplantation is the definitive therapy for cirrhosis, and malnutrition is the most frequent complication in these patients. Sarcopenia or loss of muscle mass is the major component of malnutrition in cirrhotics and adversely affects their outcome. In addition to the metabolic consequences, functional consequences of sarcopenia include reduced muscle strength and deconditioning. Despite nearly universal occurrence of sarcopenia and its attendant complications, there are no established therapies to prevent or reverse the same. Major reasons for this deficiency include the lack of established standardized definitions or measures to quantify muscle mass, as well as paucity of mechanistic studies or identified molecular targets to develop specific therapeutic interventions. Anthropometric evaluation, bioelectrical impedance analysis, and DEXA scans are relatively imprecise measures of muscle mass, and recent data on imaging measures to determine muscle mass accurately are likely to allow well-defined outcome responses to treatments. Resurgence of interest in the mechanisms of muscle loss in liver disease has been directly related to the rapid advances in the field of muscle biology. Metabolic tracer studies on whole body kinetics have been complemented by direct studies on the skeletal muscle of cirrhotics. Hypermetabolism and anabolic resistance contribute to sarcopenia. Reduced protein synthesis and increased autophagy have been reported in cirrhotic skeletal muscle, while the contribution of the ubiquitin-proteasome pathway is controversial. Increased plasma concentration and skeletal muscle expression of myostatin, a TGFβ superfamily member that causes reduction in muscle mass, have been reported in cirrhosis. Hyperammonemia and TNFα have been reported to increase myostatin expression and may be responsible for sarcopenia in cirrhosis. Nutriceutical interventions with leucine enriched amino acid mixtures, myostatin antagonists and physical activity hold promise as measures to reverse sarcopenia. There is even less data on muscle function and deconditioning in cirrhosis and studies in this area are urgently needed. Even though macronutrient replacement is a major therapeutic goal, micronutrient supplementation, specifically vitamin D, is expected to improve outcomes.

Posttransplant sarcopenia: an underrecognized early consequence of liver transplantation

Liver transplantation is believed to reverse the clinical and metabolic abnormalities of cirrhosis. Reduced skeletal muscle mass or sarcopenia contributes to increased mortality and adverse consequences of cirrhosis. Failure of reversal of sarcopenia of cirrhosis after liver transplantation is not well recognized. Six temporally, geographically, and methodologically distinct follow-up studies in 304 cirrhotics reported conflicting data on changes in indirect measures of skeletal muscle mass after transplantation. Distinct measures of body composition but not skeletal muscle mass were used and did not focus on the clinical consequences of sarcopenia after transplantation. A number of studies reported an initial rapid postoperative loss of lean mass followed by incomplete recovery with a maximum follow-up of 2 years. Posttransplant sarcopenia may be responsible for metabolic syndrome and impaired quality of life after liver transplantation. Potential reasons for failure to reverse sarcopenia after liver transplantation include use of immunosuppressive agents [mammalian target of rapamycin (mTOR) and calcineurin inhibitors] that impair skeletal muscle growth and protein accretion. Repeated hospitalizations, posttransplant infections, and renal failure also contribute to posttransplant sarcopenia. Finally, recovery from muscle deconditioning is limited by lack of systematic nutritional and physical-activity-based interventions to improve muscle mass. Despite the compelling data on sarcopenia before liver transplantation, the impact of posttransplant sarcopenia on clinical outcomes is not known. There is a compelling need for studies to examine the mechanisms and consequences of sarcopenia post liver transplantation to permit development of therapies to prevent and reverse this disorder.

Muscle mass predicts outcomes following liver transplantation

For patients with end-stage liver disease, commonly used indices of nutritional status (ie, body weight and body mass index) are often inflated because of fluid overload (ie, ascites and peripheral edema), and this results in an underdiagnosis of malnutrition. Because muscle is the largest protein reservoir in the body, an estimate of the muscle mass may be a more reliable and valid estimate of nutritional status. Therefore, we used pretransplant computed tomography data for 338 liver transplantation (LT) candidates to identify muscle and fat mass on the basis of a specific abdominal transverse section commonly used in body composition analyses, and we investigated the contribution of this measure to specific post-LT outcomes. We found that the majority of our patients (68%) could be defined as cachectic. For men, muscle mass predicted many important posttransplant outcomes, including intensive care unit (ICU) stay, total length of stay (LOS), and days of intubation. Muscle mass was a significant predictor of survival and also predicted disposition to home versus another facility. For women, muscle mass predicted ICU stay, total LOS, and days of intubation, but the effect was modest. Muscle mass did not predict survival or disposition for women. In conclusion, because pretransplant muscle mass is associated with many important postoperative outcomes, we discuss these findings in the context of possible pretransplant interventions for either improving or sustaining muscle mass before surgery.