The functional, metabolic, and anabolic responses to exercise training in renal transplant and hemodialysis patients.

BACKGROUND: Exercise intolerance is common in hemodialysis (HD) and renal transplant (RTx) patients and is related to muscle weakness. Its pathogenesis may vary between these groups leading to a different response to exercise. The aim of the study was to compare intrinsic muscular parameters between HD and RTx patients and controls, and to assess the response to exercise training on exercise capacity and muscular structure and function in these groups. METHODS: Quadriceps function (isokinetic dynamometry), body composition (dual-energy x-ray absorptiometry), and vastus lateralis muscle biopsies were analyzed before and after a 12-week lasting training-program in 35 RTx patients, 16 HD patients, and 21 healthy controls. RESULTS: At baseline, myosin heavy chain (MyHC) isoform composition and enzyme activities were not different between the groups. VO2peak and muscle strength improved significantly and comparably over the training-period in RTx, HD patients and controls (p(time)<0.05). The proportion of MyHC type I isoforms decreased (p(time)<0.001) and type IIa MyHC isoforms increased (p(time)<0.05). The 3-hydroxyacyl-CoA-dehydrogenase activity increased (p(time)=0.052). Intrinsic muscular changes were not significantly different between groups. In the HD group, changes in lean body mass were significantly related to changes in muscle insulin-like growth factor (IGF)-II and IGF binding protein-3. CONCLUSIONS: Abnormalities in metabolic enzyme activities or muscle fiber redistribution do not appear to be involved in muscle dysfunction in RTx and HD patients. Exercise training has comparable beneficial effects on functional and intrinsic muscular parameters in RTx patients, HD patients, and controls. In HD patients, the anabolic response to exercise training is related to changes in the muscle IGF system.

Similarities in skeletal muscle strength and exercise capacity between renal transplant and hemodialysis patients.

Exercise intolerance is common in hemodialysis (HD) and renal transplant (RTx) patients. Aim of the study was to assess to what extent exercise capacity and skeletal muscle strength of RTx patients differ from HD patients and healthy controls and to elucidate potential determinants of exercise capacity in RTx patients. Exercise capacity, muscle strength, lean body mass (LBM) and physical activity level (PAL) were measured by cycle-ergometry, isokinetic dynamometry, DEXA and Baecke Questionnaire, respectively, in 35 RTx, 16 HD and 21 controls. VO2peak and muscle strength of the RTx patients were significantly lower compared to controls (p<0.01), but not different compared to HD patients. In RTx patients, strength (p<0.001), PAL (p=0.001) and age (p=0.045) were significant predictors of VO2peak. Muscle strength was related to LBM (p=0.001) and age (p=0.001), whereas gender (p<0.001) and renal function (p=0.01) turned out to be significant predictors of LBM. No effects of corticosteroids were observed. Exercise capacity and muscle strength seem equally reduced in RTx and HD patients compared to controls. In RTx patients, muscle strength and PAL are highly related to exercise capacity. Renal function appears to be a significant predictor of LBM, and through the LBM, of muscle strength and exercise capacity.

Nutritional considerations in renal transplant patients.

In renal transplant patients, weight gain generally increases after renal transplantation, which will be influenced by improved appetite and a reversal of the uremic state. However, at least in the early posttransplant period, the increase in body weight is mainly due to an increase in body fat mass. This phenomenon may be partly due to relatively high doses of steroids in the early period after renal transplantation, possibly mediated by their inhibiting effect on lipid peroxidation, but also appears to be related to physical inactivity. The increase in body fat mass may contribute to posttransplant hyperlipidemia, which is improved but not completely normalized by dietary intervention. Current dietary recommendations in stable renal transplant patients do not generally differ from those of the general population, although intense dietary counselling may be indicated in patients with excessive posttransplant weight gain. The effect of supervised exercise training on body composition is currently under investigation.

The influence of early steroid withdrawal on body composition and bone mineral density in renal transplantation patients.

Corticosteroid treatment may have an important effect on body composition and bone mineral density (BMD) in renal transplantation (RTx) patients. We investigated the effect of early steroid withdrawal on body composition and BMD of RTx patients in a prospective design. Post-transplant immunosuppression consisted of tacrolimus, mycophenolate mofetil, and prednisolone. Three months after RTx, 27 patients participating in a multi-center trial were randomized either to continue steroids (at a dose of 10 mg/day, n=17; steroid+) or be withdrawn from steroids within 2 weeks (n=10; steroid-). Body composition and BMD (lumbar spine (L2-L4) and femoral neck) were measured by dual-energy X-ray absorptiometry (DEXA) just before and 3 months after randomization. With regard to body composition, fat mass tended to increase in the steroid+ group (1.1+/-2.3 kg; P=0.084), but did not change in the steroid- group. Increase in body fat percentage tended to be higher (P=0.08) in the steroid+ group (0.6+/-2.7%) than in the steroid- group (-0.7+/-2.1%). The change in lean body mass was not significantly different between the two groups. BMD of the lumbar spine and femoral neck decreased significantly in the steroid+ group (-1.4+/-3.2% and -2.3+/-2.9%, respectively, P<0.05) while no changes were observed in the steroid- group. The change in BMD of the lumbar spine was significantly different between the steroid+ and the steroid- group, whereas the change in BMD of the femoral neck was not significantly different. Thus, the increase in fat mass tended to be higher in the group continuing on steroids, though not significant, due to large inter-individual variation. In general, the effect of early steroid withdrawal on body composition after RTx appears to be modest. In addition, early steroid withdrawal seems to have beneficial effects on BMD in RTx patients, especially in the lumbar region.

Weight changes after renal transplantation: a comparison between patients on 5-mg maintenance steroid therapy and those on steroid-free immunosuppressive therapy.

After renal transplantation (RTx), an increase in body weight (BW) is usually observed, in which corticosteroids may play an important role. However, the effects of a low maintenance dosage of corticosteroids on BW have not been studied longitudinally in RTx patients. The aim of this study was to compare changes in BW after RTx in patients on steroid- or steroid-free immunosuppressive therapy and to assess the relationship between post-transplant weight changes and other potentially important factors. The charts of 123 RTx patients (72 male, 51 female) were retrospectively examined for BW changes in the first 5 years after RTx. Sixty-six patients were on 5-mg maintenance steroid dose and 57 patients underwent steroid-free immunosuppression. Mean post-transplant BW gain was 3.0+/-5.3 kg after 6 months, 3.9+/-6.2 kg after 1 year and 6.2+/-8.6 kg after 5 years. Weight gain in the first year after RTx was related neither to maintenance- nor to cumulative steroid dose, age, gender, occurrence of rejection, or renal function. Weight gain was, however, significantly related to pre-transplant BMI and dialysis modality. After the first year, weight gain was significantly and positively related only to the cumulative steroid dose. The course of weight gain in the first year after RTx turned out to be independent from factors such as maintenance- or cumulative steroid dose, age, gender, occurrence of rejection, and renal function; weight gain was, however, dependent on pre-transplant BMI and dialysis modality. After the first year, the weight course was significantly affected by cumulative steroid dose.