Overtraining syndrome (
OTS) is caused by an imbalance between training, nutrition and resting, and leads to decreased performance and
fatigue; however, the precise underlying triggers of
OTS remain unclear. This study investigated the body composition, metabolism, eating, sleeping patterns and mood states among participants with
OTS. Selected participants were divided into
OTS-affected athletes (
OTS, n = 14), healthy athletes (ATL, n = 25), and healthy non-physically active controls (NCS, n = 12). Compared to ATL,
OTS showed decreased sleep quality (p = 0.004); increased duration of work or study (p < 0.001); decreased libido (p = 0.024); decreased calorie (p < 0.001),
carbohydrate (p < 0.001) and
protein (p < 0.001) intakes; decreased mood states (p < 0.001); decreased basal metabolic rate (p = 0.013) and fat burning (p < 0.001); increased body fat (p = 0.006); decreased muscle mass (p = 0.008); and decreased hydration (p < 0.001). Levels were similar between
OTS and NCS, except for worsened
fatigue (p < 0.001) and vigour (p = 0.001) in
OTS. Reduced calorie intake, worsened sleep, and increased cognitive activity are likely
OTS triggers.
OTS appears to induce
dehydration, increase body fat, decrease libido, and worsen mood.