Patients with schizophrenia die decades earlier than the general population. Among the factors involved in this mortality gap, evidence suggests a telomere length shortening in this clinical population, which is associated with premature ageing. Recent studies support the use of strength-based training exercise programmes to maintain, or even elongate, telomere length in healthy elderly populations. However, studies aiming at modifying telomere length in severe mental illnesses, such as schizophrenia, are still very scarce.To investigate the effect of a strength-based physical exercise programme on the telomere length of individuals with schizophrenia.We propose a pragmatic, randomised controlled trial including 40 patients aged ≥18 years, with a stable diagnosis of schizophrenia, attending the Complejo de Rehabilitación Psicosocial (CRPS, Psychosocial Rehabilitation Centre) in Salamanca, Spain. These patients will be randomly assigned (1:1) to either receive the usual treatment and rehabilitation programmes offered by CRPS (treatment-as-usual group) or these plus twice weekly sessions of an evidence-based, strength-based training exercise programme for 12 weeks (intervention group). The primary outcome will be effect on telomere length. Secondary outcomes will include impact on cognitive function, frailty and quality of life.We expect to show the importance of implementing strength-based physical exercise programmes for patients with schizophrenia. We could find that such programmes induce biological and genetic changes that may lengthen life expectancy and decrease physical fragility.We anticipate that our trial findings could contribute to parity of esteem for mental health, reducing premature ageing in patients with severe mental illnesses, such as schizophrenia.