Muscle fatigue in women with primary biliary cirrhosis: Spectral analysis of surface electromyography

Physical exercise for people with cirrhosis

BACKGROUND

Loss of muscle mass and muscle weakness are common complications to cirrhosis and are associated with increased morbidity and mortality. Therefore, physical exercise may benefit people with cirrhosis.

OBJECTIVES

To assess the beneficial and harmful effects of physical exercise versus sham exercise or no exercise for people with cirrhosis.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE Ovid, Embase Ovid, and three other databases, including manual searches through reference lists, abstracts, and presentations at conferences and meetings, Google Scholar, and online trial registers in February 2018.

SELECTION CRITERIA

We included randomised clinical trials regardless of publication status or language. Inclusion criteria were cirrhosis irrespective of the aetiology or stage. Interventions were physical exercise compared with sham exercise or no intervention.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data. We undertook meta-analyses and presented results using risk ratios (RR) for dichotomous outcomes and mean differences (MD) for continuous outcomes, both with 95% confidence intervals (CI) and I² values as markers of imprecision and heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary Group domains and determined the credibility of the evidence using GRADE.

MAIN RESULTS

We included six randomised clinical trials with 173 participants. All participants had Child-Pugh stage A or B cirrhosis. The intervention groups participated in eight to 14 weeks of physical exercise (aerobic: three trials; resistance: one trial; or aerobic plus resistance training: two trials). Control groups underwent sham exercise (supervised relaxation: one trial) or no intervention (five trials). None of the 89 participants allocated to exercise versus two of 84 participants in the control group died (RR 0.19, 95% CI 0.01 to 3.73; moderate-quality evidence). The cause of death was acute-on-chronic liver disease for both participants. Nine participants in the exercise group and 13 in the control group experienced serious adverse events (RR 0.61, 95% CI 0.19 to 1.94; low-quality evidence).Physical exercise showed no beneficial or detrimental effect on health-related quality of life assessed by the Chronic Liver Disease Questionnaire (MD 0.11, 95% CI -0.44 to 0.67; low-quality evidence). Likewise, physical exercise had no clear effect on physical fitness measured by peak exercise oxygen uptake (MD 0.3 mL/kg/minute, 95 % CI -2.74 to 3.35; low-quality evidence) and Six-Minute Walk Test (MD 56.06 min, 95% CI -9.14 to 121.26; very low-quality evidence). Physical exercise showed no clear effect on mid-thigh circumference (MD 1.76 cm, 95% CI -0.26 to 3.77; low-quality evidence), but showed an increase in mid-arm circumference (MD 2.61 cm, 95% CI 0.36 to 4.85; low-quality evidence).

AUTHORS' CONCLUSIONS

We found no clear beneficial or harmful effect of physical exercise on mortality, morbidity, or health-related quality of life. Further evidence is needed to evaluate the beneficial and harmful effects of physical exercise on clinical outcomes.

Hyperammonemia results in reduced muscle function independent of muscle mass

The mechanism of the nearly universal decreased muscle strength in cirrhosis is not known. We evaluated whether hyperammonemia in cirrhosis causes contractile dysfunction independent of reduced skeletal muscle mass. Maximum grip strength and muscle fatigue response were determined in cirrhotic patients and controls. Blood and muscle ammonia concentrations and grip strength normalized to lean body mass were measured in the portacaval anastomosis (PCA) and sham-operated pair-fed control rats (n = 5 each). Ex vivo contractile studies in the soleus muscle from a separate group of Sprague-Dawley rats (n = 7) were performed. Skeletal muscle force of contraction, rate of force development, and rate of relaxation were measured. Muscles were also subjected to a series of pulse trains at a range of stimulation frequencies from 20 to 110 Hz. Cirrhotic patients had lower maximum grip strength and greater muscle fatigue than control subjects. PCA rats had a 52.7 ± 13% lower normalized grip strength compared with control rats, and grip strength correlated with the blood and muscle ammonia concentrations (r(2) = 0.82). In ex vivo muscle preparations following a single pulse, the maximal force, rate of force development, and rate of relaxation were 12.1 ± 3.5 g vs. 6.2 ± 2.1 g; 398.2 ± 100.4 g/s vs. 163.8 ± 97.4 g/s; -101.2 ± 22.2 g/s vs. -33.6 ± 22.3 g/s in ammonia-treated compared with control muscle preparation, respectively (P < 0.001 for all comparisons). Tetanic force, rate of force development, and rate of relaxation were depressed across a range of stimulation from 20 to 110 Hz. These data provide the first direct evidence that hyperammonemia impairs skeletal muscle strength and increased muscle fatigue and identifies a potential therapeutic target in cirrhotic patients.