Aerobic, Resistance and Inspiratory Muscle Training in Adults With Severe Mental Illness

Study design and setting

This is a single-arm, 12-week supervised exercise intervention conducted at the Centre for Sport and Physical Performance Research (CIRFD) of Universidad Pablo de Olavide, Seville, Spain. The setting is a university research facility rather than a clinical environment. Participants were recruited in collaboration with three mental health services of differing nature: a community social integration programme (Fundación Pública Andaluza para la Integración Social de Personas con Enfermedad Mental, FAISEM), a mental health day hospital (Hospital Universitario Nuestra Señora de Valme), and a residential therapeutic community (Comunidad Terapéutica de Salud Mental El Tomillar). Participants continued their usual psychiatric treatment throughout the intervention and received no financial compensation.

Intervention structure

The programme consists of 24 sessions delivered twice weekly over 12 weeks. Each session lasts 45-60 minutes and combines three consecutive training blocks: interval aerobic training, resistance training, and inspiratory muscle training. Participants train in groups of up to eight. Each session is supervised by an exercise professional with more than two years of experience working with adults with severe mental illness, a research support technician holding a degree in Sport and Exercise Sciences, and two Sport and Exercise Sciences students. Training loads are adapted at every session to the physical and mental state of each participant.

Aerobic training

Aerobic training is performed on a cycle ergometer (Ergoselect 200K; Ergoline, Bitz, Germany) using a 20-minute interval protocol alternating 1 minute of high intensity with 1 minute of active recovery. Intensity is individualised from peak power output (PPO), determined by an incremental cardiopulmonary exercise test performed at baseline and repeated at week 6 to readjust loads. During testing, intensity is increased progressively until the participant cannot maintain a pedalling cadence of 60-70 rpm; perceived exertion is recorded using the Borg 0-10 scale and cardiopulmonary variables are monitored with a gas analyser (Cosmed K5; Cosmed, Rome, Italy). Load progression is as follows: weeks 1-2 at 65% PPO, weeks 3-4 at 70%, weeks 5-6 at 75%, weeks 7-8 at 80%, weeks 9-10 at 85%, week 11 at 90%, and week 12 at 100% PPO. Recovery intervals are maintained at 30% PPO throughout. Participants sustain a cadence of 60-70 rpm and are monitored in real time by supervisors.

Resistance training

Resistance training consists of a circuit of digitally controlled machines (eGym, Stuttgart, Germany) comprising pec deck, chest press, seated row, shoulder press, lat pulldown, leg press and leg extension. Each session includes three complete circuits (approximately 20 minutes), with 20 seconds of transition between machines and 1 minute of rest between circuits. Loads are individualised through the maximal strength estimation integrated in the eGym system, assessed at baseline and reconfigured periodically. Estimation is performed on each machine using a gamified test in which the participant executes one repetition at maximal force on three occasions, with the highest value used to configure training. Periodisation follows three blocks: weeks 1-4 at 50-60% 1RM, weeks 5-8 at 55-65% 1RM, and weeks 9-12 at 60-70% 1RM, with 10-16 repetitions and a work-to-rest ratio progressing from 30:20 to 45:20 seconds. Technical execution is prioritised and muscular failure is avoided.

Inspiratory muscle training

Inspiratory muscle training is performed with a pressure threshold loading device (POWERbreathe Classic Medium Resistance; POWERbreathe International Ltd., UK), in standing position, consisting of 6 sets of 5 maximal-effort inspirations with complete expirations and 60 seconds of rest between sets. Loads are individualised from maximal inspiratory pressure (MIP), measured with a portable mouth pressure meter (MicroRPM; Micro Medical Inc., Chatham, Kent, UK), with the highest of several maximal inspiratory efforts used to configure training. Progression is as follows: week 1 at 15% MIP, week 2 at 30%, week 3 at 35%, week 4 at 40%, weeks 5-6 at 45%, weeks 7-8 at 50%, weeks 9-10 at 55%, and weeks 11-12 at 60% MIP. MIP is reassessed at week 6 to adjust loads. In contrast to protocols commonly applied in other clinical populations, training frequency is set at two days per week to maximise initial tolerance and adherence in a population characterised by respiratory muscle deconditioning and reduced exercise capacity.

Adherence support strategies

Motivational strategies are integrated throughout the programme, grounded in Self-Determination Theory and classified according to the Behaviour Change Technique Taxonomy v1, with the aim of supporting the basic psychological needs of competence, autonomy and relatedness. These include: an individualised step challenge based on daily monitoring with activity wristbands (Xiaomi Mi Band 4) and weekly personalised step goals derived from a 10-day rolling window; weekly educational and motivational content delivered by instant messaging the day before each session; a mid-intervention peer support group meeting facilitated by staff acting solely as moderators; continuous bidirectional communication between professionals and participants; systematic positive feedback during sessions and remote contacts; advance planning through a fixed structure of schedules, locations and session duration; promotion of social support through the group format and collaboration with mental health services; intermediate fitness assessments to monitor progress and make gains visible; active follow-up after any absence through direct contact to identify barriers and offer support; continuous supervision by exercise professionals; and individualised, flexible adaptation of training according to clinical status and exercise response.

Assessment schedule

Assessments are conducted at baseline (two weeks before the intervention), at mid-intervention (week 6, to readjust training loads), and after completion of the 12-week programme. Semi-structured interviews exploring participants' experience of the programme are conducted at the end of the intervention with participants who completed the programme and with those who withdrew and could be contacted.

Reporting and methodological framework

The intervention was designed following the PADEX guideline for promoting exercise adherence in people with chronic conditions. Reporting of the intervention follows the Consensus on Exercise Reporting Template (CERT). Reporting of study findings follows the TREND statement for non-randomised evaluations and, for the qualitative component, the Reflexive Thematic Analysis Reporting Guidelines

Inclusion criteria

• Medical diagnosis of severe mental illness according to ICD-10 criteria
• Aged between 18 and 65 years
• Clinical stability confirmed by the participant's mental health professionals
• Physically able to perform exercise
• Able to travel to the intervention site
• Written informed consent

Exclusion criteria

• Acute psychiatric decompensation at the time of enrolment
• Medical condition contraindicating exercise participation, including uncontrolled cardiovascular disease
• Inability to complete baseline assessments
• Currently participating in another structured exercise programme