O59
EFFECTS OF RESISTANCE EXERCISE TRAINING ON MYOGENIC RESPONSE TO
ACUTE EXERCISE IN CHRONIC KIDNEY DISEASE
Watson EL1, Greening N2, Viana JL1,3, Barratt J1, and Smith AC1
1
Leicester Kidney Exercise Team, John Walls Renal Unit, University Hospitals of
Leicester NHS Trust & Dept of Infection, Immunity and Inflammation, University of
Leicester;
2
Institute for Lung Health, Department of Respiratory Medicine, University Hospitals of
Leicester NHS Trust, Leicester;
3
School of Sport, Exercise and Health Sciences, Loughborough University.
Background: Patients with chronic kidney disease (CKD) suffer from skeletal muscle wasting.
In healthy individuals, resistance exercise (RE) is anabolic, but its potential to overcome muscle
wasting in CKD has not been well studied. Muscle growth in response to RE is controlled by
many factors, including myogenic factors Myostatin, Myogenin and MyoD. Typically
Myostatin is a negative regulator of growth and its expression is supressed following RE, whilst
Myogenin and MyoD positively regulate growth and their expression is increased. It is
unknown how these factors respond to acute resistance exercise in pre-dialysis CKD and
therefore the aim of this study was to investigate the effect of resistance exercise training on
muscle mass and molecular responses to acute RE in pre-dialysis CKD.
Methods: 18 patients with CKD3b-4 (mean eGFR 23, range 16-36ml/min/1.73m2; mean age
63, range 45-77 years) were randomised to RE (3 sets of 10-12 leg extensions at 70%
maximum, 3/week for 8 weeks; n=11), or control (usual activity; n=7). Quadriceps muscle
volume was measured by 3-dimensional ultrasonography at baseline and 8 weeks. Muscle
biopsies were obtained at baseline and 8 weeks in controls, and baseline, 24h post first training
session (PRE-RT) and 24h post final training session (POST-RT) in exercisers. Myostatin,
Myogenin and MyoD mRNA expression were analysed by RT-PCR and calculated according to
2-ΔΔCT.
Results: No changes were seen in the controls. In exercisers, 8 weeks RE significantly
increased quadriceps muscle volume (baseline 153±9 to 8weeks 168±11cm3; P=0.009). In
contrast to the expected response in healthy individuals, no change was seen in Myogenin or
Myostatin mRNA expression from baseline in response to a bout of RE at either PRE-RT or
POST-RT. MyoD mRNA expression was slightly supressed 1.25-fold from baseline at PRE-RT
(P=0.05), which was then seen to increase 1.5-fold above baseline at POST-RT, but this was not
significant (P=0.18).
Conclusions: This study reveals a previously unknown abnormal myogenic response to a single
bout of RE compared to healthy individuals, which appears to be partially corrected by 8 weeks
of RE. This novel finding suggests that patients with CKD have impaired muscle remodelling
and reconditioning in the untrained condition. However, 8 weeks RE is effective at stimulating
muscle hypertrophy therefore potentially overcoming muscle wasting in pre-dialysis CKD,
which has important clinical implications.