A systematic review and meta-analysis of the effects of aerobic exercise interventions on cardiorespiratory fitness in adults with intellectual disability

Adults with an intellectual disability (ID) have low cardiorespiratory fitness (CRF). Low CRF has been associated with a high risk of cardiovascular disease and all-cause mortality. Participation in regular exercise can help adults with ID increase their CRF. To perform a systematic review and meta-analysis of published, peer-reviewed clinical trials that evaluated the effects of aerobic exercise (AE) interventions on CRF in adults with ID, ages 18–65 years. English-language articles were searched up to June 2021 from 11 electronic databases. Data were extracted using an author-developed form. Two independent authors assessed the risk of bias using the Tool for the Assessment of Study Quality and reporting in Exercise (TESTEX). Meta-analysis was performed using the RevMan 5.3. Of the 1870 article titles and abstracts screened, 16 articles were included. The average TESTEX score (out of 15) was 8.1 (SD = 3.5, range 2–14). The pooled effect was statistically significant (SMD = 0.41, 95% CI: 0.19 to 0.63, z = 3.59; p = .000) with moderate heterogeneity (I2 = 35%, p = .000). Both types of intervention produced statistically significant CRF gains, with interventions that combined AE with resistance, balance, and/or flexibility exercises being slightly more effective (SMD = 0.40, 95% CI: 0.11 to 0.70, p = .007) than non-combined interventions (SMD = 0.42, 95% CI: 0.05 to 0.79, p = .02). Heterogeneity was moderate but non-significant for both types of intervention. The review supports the use of AE interventions in promoting CRF in adults with ID. The interpretation is limited by the quality of evidence and by poorly described and/or executed familiarization and measurement protocols.