Strength training restores force-generating capacity in patients with schizophrenia

Patients with schizophrenia spectrum disorders have impaired skeletal muscle force-generating capacity (FGC) of the lower extremities, that is, one repetition maximum (1RM) and rapid force development, and poor functional performance. We therefore investigated whether 12 weeks of maximal strength training (MST) could (a) restore FGC and functional performance to the level of healthy references, (b) increase patient activation and quality of life, and (c) explore associations between symptom severity, defined daily dose of medication, illness duration, level of patient activation, and improvements in FGC and functional performance. Forty-eight outpatients were randomized to a training group (TG) or control group (CG). TG performed leg press MST 2 day/week at ~ 90% 1RM. The CG received two introductory training sessions and encouragement to train independently. Leg press 1RM, rapid force development, a battery of functional performance tests, Patient Activation Measure-13, and 36-Item Short Form Health Survey were tested. Healthy references performed baseline tests of FGC and functional performance. Thirty-six patients completed the study (TG: 17, CG: 19). TG improved 1RM (28%) and rapid force development (20%, both P < .01) to a level similar to healthy references, while no change was apparent in the CG. TG's improvement in rapid force development was negatively associated with defined daily dose of medication (r = -0.5, P = .05). Both TG and CG improved 30-second sit-to-stand test performance (P < .05) which was associated with improved rapid force development (r = 0.6, P < .05). In conclusion, 12 weeks of MST restored patients' lower extremity FGC to a level similar to healthy references and improved 30-second sit-to-stand test performance.