Patients with schizophrenia have impaired muscle force‐generating capacity and functional performance

Abstract

Patients with schizophrenia have impaired physical health. However, evidence of how skeletal muscle force‐generating capacity (FGC), a key component of functional performance, may contribute to the impairment is scarce. Thus, the aim of this study was to investigate the patient groups’ skeletal muscle FGC and its association with functional performance. Leg‐press FGC was assessed along with a battery of functional performance tests in 48 outpatients (28 men, 34 ± 10 years; 20 women, 36 ± 12 years) with schizophrenia spectrum disorder (ICD‐10, F20‐29), and compared with 48 healthy age‐ and gender‐matched references. Results revealed reduced one‐repetition maximum (1RM) in men (−19%, P < .01) and a trend toward reduction in women (−13%, P = .067). The ability to develop force rapidly was also impaired (men: −30%; women: −25%, both P < .01). Patients scored worse than healthy references on all physical performance tests (stair climbing: −63%; 30‐second sit‐to‐stand (30sSTS): −48%; six‐minute walk test (6MWT): −22%; walking efficiency: −14%; and unipedal stance eyes open: −20% and closed: −73%, all P < .01). 1RM correlated with 6MWT (r = .45), stair climbing (r = −.44), 30sSTS (r = .43), walking efficiency (r = .26), and stance eyes open (r = .33) and closed (r = .45), all P < .01. Rapid force development correlated with 6MWT (r = .54), stair climbing (r = −.49), 30sSTS (r = .45), walking efficiency (r = .26), and stance eyes open (r = .44) and closed (r = .51), all P < .01. In conclusion, skeletal muscle FGC and functional performance are reduced in patients with schizophrenia and should be recognized as important aspects of the patient groups’ impaired health. Resistance training aiming to improve these components should be considered an important part of clinical treatment.

Strength training restores force‐generating capacity in patients with schizophrenia

“…The previously documented impairment in muscular strength in this patient group 1 was restored to that of the healthy reference group after only 12 weeks of leg press MST. This is promising as low muscular strength is associated with a significantly higher risk of premature mortality due to cardiovascular disease, cancer, and all‐cause mortality 4,5 .…”

“…Recent research from our laboratory documented impaired lower extremity muscle force‐generating capacity accompanied by reduced functional performance in outpatients with schizophrenia spectrum disorders 1 . Therefore, the aim of this study was to investigate whether 12 weeks of supervised leg press MST could improve 1RM and rapid force development to a level observed in healthy references in addition to increase functional performance, patient activation, and quality of life.…”

“…Patients with schizophrenia often suffer from negative symptoms such as apathy, lack of motivation and initiative, and capacity to sustain and shift in focus when necessary 38 making real‐world functioning a difficult endeavor. Indeed, previous research indicates that many of the patients found these tests of functional performance hard to perform 1 . Additionally, most of the patients were on antipsychotic medical treatment with side effects that might hamper the performance of explosive movements.…”

“…Recent research from our group documented impaired lower extremity muscle force‐generating capacity, measured as maximal muscle strength (1RM) and rapid force development in patients with schizophrenia, and their association with functional performance parameters such as walking, stair‐climbing, chair‐rising, and balance 1 . Both aforementioned force parameters are key determinants for functional performance in tasks of everyday life 2,3 .…”

“…As poor muscle force‐generating capacity is associated with poor functional performance, 1 and maximal strength training is an effective method to rapidly improve muscle force‐generating capacity, 12 the primary aim of this study was to investigate whether 12 weeks of MST in patients with schizophrenia spectrum disorder could improve muscle force‐generating capacity to a level observed in healthy references. The secondary aims were to investigate whether MST also improved functional performance, patient activation regarding their physical health (Patient Activation Measure‐13), and health‐related quality of life (36‐Item Short Form Health Survey).…”