O28
RESISTANCE EXERCISE INCREASES MUSCLE MASS AND PRESERVES
INTRAMUSCULAR AMINO ACID CONCENTRATIONS IN PRE-DIALYSIS CKD: A
RANDOMISED CONTROLLED TRIAL
Watson, E1, Greening, N2, Aulakha, J1, Ruttanaporn, N1, Young, H2, Dungey, M3, Burton, J2,
Barratt, J1, Smith, A2,1
1
Department of Infection, Immunity and Inflammation, University of Leicester, 2John Walls
Renal Unit, Leicester General Hospital, 3School of Sport, Exercise and Health Sciences,
Loughborough University
INTRODUCTION: Patients with chronic kidney disease (CKD) suffer from skeletal muscle wasting
which is associated with morbidity and mortality and worsens as renal function declines. This loss of
muscle mass leads to fatigue and weakness, and can limit the ability to take aerobic exercise which
has proven cardiovascular benefits in this very high risk population. In a previous study (1), we found
that an aerobic exercise programme failed to increase muscle mass in CKD, and instead resulted in
depletion of intramuscular free amino acids. Progressive resistance exercise (PRE) effectively
stimulates muscle hypertrophy in the general population, but its ability to overcome the catabolic
influences associated with pre-dialysis CKD has not been properly studied. The aim of this
randomised controlled trial was to investigate the effects of an 8 week PRE programme in CKD
patients stage 3b-4.
METHODS: 20 patients (10 males, 63[45-80] years, eGFR 28[15-37] ml/min/1.73m2) were
randomised to PRE training consisting of 3 sets of 10-12 leg extensions at 70% 1 repetition
maximum, 3 times a week for 8 weeks. 18 patients were randomised to control (13 male, 65.5[45-79]
years, eGFR 20.5[15-40] ml/min/1.73m2) and continued with their usual physical activity. Outcome
assessments were carried out at baseline and 8 weeks and included rectus femoris anatomical crosssectional area (ACSA) by ultrasonography, isokinetic muscle strength by dynamometry, exercise
capacity by endurance shuttle walk test (ESWT), and patient perception of common uraemic
symptoms by questionnaire. Rectus femoris muscle biopsies were obtained in the fasted state at
baseline and 8 weeks, and intramuscular amino acid concentration determined by high performance
liquid chromatography (HPLC).
RESULTS: 18 exercisers and 15 controls completed the study. Adherence to PRE was good, with a
92% attendance rate at exercise sessions. No changes were seen in the controls for any outcome
measure, except for a decrease in the time walked in the ESWT (P=0.03) indicating reduced exercise
capacity. In contrast, patients who undertook the PRE programme had a significant increase in EWST
walking performance (9.7±7.7 vs 12.4±8.0min P=0.03), and reported a significant reduction of the
impact of uraemic symptoms (p=0.01). The exercise group also had significantly increased ACSA
(6.03±2.1 vs 6.6±2.2cm2 P=0.002) and knee extensor strength (95.6±8.2 vs 108.9±8.5Nm, p<0.001),
and HPLC analysis of muscle biopsies demonstrated preservation of free amino acid levels (p>0.05
for all 17 amino acids measured) following exercise training.
CONCLUSION: 8 weeks of PRE resulted in significant gains in skeletal muscle and strength and
maintained intramuscular amino acid concentrations, the depletion of which may limit ability to
increase muscle mass in response to exercise. These results indicate that PRE can effectively
overcome catabolic influences to preserve or improve muscle mass in CKD. Furthermore, although
the exercise programme did not include aerobic training, walking performance significantly improved,
suggesting that muscle wasting and weakness is an important limiting factor in physical capacity in
CKD. This study demonstrates that PRE is a well-tolerated and effective strategy to maintain muscle
mass, physical functioning and quality of life in patients with CKD.
Ref :(1) Collapse of intramuscular free amino acid pools in patients with CKD4-5 after 6 months of
walking exercise is prevented by alkali supplements, Clapp et al., presented at International Congress
on Nutrition and Metabolism in Renal Disease,2010.