We like to move it - patients with schizophrenia spectrum disorders are impaired in estimating their physical fitness levels and benefit from individualized exercise.

Background: People with schizophrenia spectrum disorders (SSD) engage less in physical activity than healthy individuals. The impact of subjectively assessed physical fitness levels on motivation for sports engagement and its relation to objective fitness parameters in SSD is unclear.

Methods: 25 patients with SSD (P-SSD) and 24 healthy controls (H-CON) participated in a randomized controlled study. Individual anaerobic thresholds (AT) were determined by an incremental exercise test and on separate days, aerobic exercise (cycling at 80% of workload at AT) and non-exercise control (sitting on an ergometer without cycling) sessions were performed. Demographic, clinical and objective physical fitness data (i.e., weekly physical activity, workload at AT, heart rate) were collected. Subjective physical fitness parameters were assessed before and after exercise and control sessions.

Results: Weekly physical activity in P-SSD was lower than in H-CON (p < 0.05) attributed to reduced engagement in sport activities (p < 0.001). Workload and percentage of predicted maximal heart rate at AT were also reduced in P-SSD compared to H-CON (both p < 0.05). Although objective and subjective physical fitness parameters were related in H-CON (p < 0.01), this relationship was absent in P-SSD. However, during exercise sessions subjective physical fitness ratings increased to a stronger extent in P-SSD than H-CON (p < 0.05).

Conclusion: The missing relationship between subjective and objective physical fitness parameters in people with SSD may represent a barrier for stronger engagement in physical activity. Accordingly, supervised exercise interventions with individually adjusted workload intensity may support realistic subjective fitness estimations and enhance motivation for sports activity in individuals with SSD.