Table 2.
Overview of discussed studies that explored relationships between fatigue and changes in body composition, inflammation and mitochondrial dysfunction.
| References | Study Design and Sample | Aim | Fatigue Assessment | Relevant Results |
|---|---|---|---|---|
| Obesity/inflammation | ||||
| Valentine et al., 2009 [61] | Cross-sectional study; 127 community-dwelling older adults. | Assess the contributions of adiposity, systemic inflammation, physical activity/fitness, sleep quality and depression on fatigue. | Two items taken from the Cohen-Hoberman Inventory of Physical Symptoms questionnaire. | Women reported more fatigue than men which was independently associated with inflammation, depression, physical activity and adiposity, whereas in men the only independent predictor was depression. |
| Valentine et al. 2011 [73] | Cross-sectional study; 182 older people. | Evaluate the influence of weight status, physical activity and inflammation on fatigue. | Multidimensional Fatigue Inventory. | Adiposity independently explained a significant amount of the variance in general and physical fatigue. |
| Resnick et al., 2006 [26] | Cross-sectional study; 3130 participants aged 20 to 59 years in the NHANES. | Examine the relationships between fatigue and BMI, waist circumference, leisure time physical activity, and macronutrient intake. | Responses to the question, “Right now would you say you are feeling energetic, fresh, average, tired or exhausted?” | Self-reported fatigue was associated with higher BMI, higher waist circumference, and a reduced likelihood of getting recommended levels of physical activity. |
| Theorell-Haglöw et al. 2006 [59] | Cross-sectional study; 5508 women aged 20 to 60 years. | Analyze the relation between different risk factors and excessive daytime sleepiness and fatigue. | Participants were asked to state how severe their problems were regarding feeling physically tired. | Being overweight was independently related to fatigue and excessive daytime sleepiness. |
| Lim et al., 2008 [58] | Cross-sectional study; 129 subjects aged 25 to 50 years. | Examine the link between obesity and depressive symptoms. | Short form of Profile of Mood States (POMS–SF) Fatigue/Inertia subscale. | Scores on POMS–SF Fatigue were positively associated with BMI and percent fat. |
| Undernutrition/nutritional deficiencies | ||||
| Singh et al., 2014 [38] | Cross-sectional study; 47 nursing home residents. | Examine the correlation between nutritional status and comprehensive physical performance measures. | Functional Ability Questionnaire. | A significant negative correlation was found between self-reported mobility tiredness and BMI. |
| Westergren et al., 2008 [37] | Cross-sectional pilot study; 89 older people discharged after stroke. | Explore associations between mealtime preparation, eating, fatigue, mood and nutritional status. | Two questions taken from the 12-item Short Form Health Survey. | Having a less favourable nutritional status was significantly predicted by a lack of energy and high age. |
| Pennisi et al., 2019 [101] | Cross-sectional study; 480 older adults. | Evaluate and compare vitamin D status between older individuals. | Fatigue severity scale (FSS). | Compared with controls, subjects with fatigue showed a significant decrease in vitamin D levels. |
| Sarcopenia/mitochondrial dysfunction | ||||
| Christie et al., 2011 [90] | Systematic Review and Meta-Analysis of 37 studies. | Compare the differences in muscle fatigue between young and older adults. | - | Older people develop less muscle fatigue than young adults, particularly during isometric contractions. However, the results also suggest that older adults develop greater fatigue during dynamic contractions, especially when the decline in power is assessed. |
| Patino-Hernandez et al., 2017 [100] | Cross-sectional study; 1509 older adults. | Examine the association among sarcopenia and its elements with depression and fatigue. | Fatigue was assessed by inquiring the participants: “In the last week: how many times have you felt that everything you do is an effort?” | Sarcopenia did not display statistically significant association with either depression or fatigue. However, both abnormal gait speed and grip strenght (two of the sarcopenia-defining variables) were associated with fatigue. |
| Wawrzyniak et al., 2016 [102] | 48 subjects aged 65+ categorized into idiopathic chronic fatigue (ICF) and non-fatigued (NF) groups | Determine whether skeletal muscle mitochondrial dysregulation and oxidative stress is linked to ICF in older adults. | Functional assessment of chronic illness therapy (FACIT) fatigue scale. | Vastus lateralis muscle biopsies were analyzed, showing reductions in mitochondrial content and suppression of mitochondrial regulatory proteins Sirt3, PGC-1α, NRF-1, and cytochrome C in ICF group compared to NF group. |
| Filler et al., 2014 [103] | Review; 25 papers of which 20 included patients with CFS/ME, which are summarized here. | Compare associations between fatigue and outcomes of mitochondrial function. | - | Most evidence for lower serum levels of CoQ10 in patients with CFS (4/4 studies). Other findings included reduced carnitine levels (4/5 studies); decreased antioxidant levels (2/2 studies); changes in mitochondrial structure (3/4 studies); and impaired energy production (2/4 studies). |
| Lacourt et al., 2018 [43] | Review; 46 papers of which 12 included CRF, 20 CFS and 14 animal models. | Compare associations between low-grade inflammation and imbalance in energy availability and expenditure. | - | Most evidence for an association between fatigue and mitochondrial functioning comes from CFS, indicating lower levels of antioxidants and possible reductions in mitochondrial ATP production. |
CFS = chronic fatigue syndrome; ME = myalgic encephalomyelitis; CRF = cancer related fatigue; ICF = idiopathic chronic fatigue; NF = non-fatigued; CDC = Centers for Disease Control and Prevention; BMI = body mass index; Sirt3 = sirtuin-3; PGC-1α = Peroxisome proliferator-activated receptor-gamma coactivator-1alpha; NRF-1 = Nuclear respiratory factor 1; CoQ10 = Coenzyme Q10.