Objective: Depressive symptomatology is more prevalent among sedentary than physically active individuals. The present prospective study examines whether withdrawal of regular aerobic activity provokes depressive mood symptoms and fatigue, and to what extent reductions in fitness levels contribute to the development of these symptoms.
Methods: Forty participants (mean age of 31.3 ± 7.5 years, 55% women) who exercised regularly (≥30 minutes aerobic exercise ≥3 times/week) were randomized to aerobic exercise withdrawal (n = 20) or to continue regular exercise (n = 20) for 2 weeks. Protocol adherence was documented using ambulatory actigraphy. Negative mood was measured with the Profile of Mood States (POMS), depressive symptoms with the Beck Depression Inventory–II (somatic and cognitive–affective components), and fatigue with the Multidimensional Fatigue Inventory (MFI). Fitness levels were documented by cycle ergometry testing.
Results: Fatigue and somatic depressive symptoms emerged after 1 week of exercise withdrawal (p = .05) and subsequently predicted the development of cognitive–affective depressive symptoms at 2 weeks (β = 0.62; p = .046). Exercise withdrawal also resulted in increased negative mood (POMS; p ≤ .01), and this increase was correlated with decreases in fitness level (r = −0.36, p = .03). Decreased fitness was related to increased POMS fatigue (p = .003) when statistically adjusting for baseline fitness levels and group condition.
Conclusion: Depressed mood and fatigue are commonly observed in individuals deprived of usual exercise activities, and the increase in fatigue may be partially mediated by reduced fitness levels. These findings may explain mood changes in response to short-term exercise withdrawal such as injuries and recovery from medical procedures that do not require full bedrest.
BDI-II = Beck Depression Inventory–II; BMI = body mass index; HR = heart rate; MET = metabolic equivalent of task; MFI = Multidimensional Fatigue Inventory; POMS = Profile of Mood States; TMD = total mood disturbance; VO2max = maximum volume of oxygen that can be used per minute; index of maximal aerobic power.