Association between physical fitness, body mass index and intelligence quotient in individuals with intellectual disabilities.
In adults with ID, stronger grip and leg muscles go hand-in-hand with higher IQ scores.
01Research in Context
What this study did
Researchers tested 91 adults with intellectual disability. They measured hand-grip and leg strength, body mass index, and IQ scores. The goal was to see if stronger bodies link to sharper minds in this group.
What they found
Medium-sized positive ties showed up. Adults with stronger hand-grip and leg strength tended to score higher on IQ tests. The pattern held after accounting for age, sex, and BMI.
How this fits with other research
Gutiérrez-Cruz et al. (2025) extends the story. They found more daily movement and less sitting link to better strength and balance in the same ID adult group. Together, the two papers suggest fit bodies support both brains and daily skills.
Boswell et al. (2023) shifts the lens to teens. In adolescents with ID, stronger muscles predicted lower body-fat, not higher IQ. The age gap explains the different outcome; both studies agree strength is a key health marker.
Alyt et al. (2014, 2015) foreshadowed these links. Their HA-ID cohort showed poor grip strength and balance forecast later loss of independence in older adults with ID. The new 2021 paper adds IQ to the list of outcomes tied to fitness.
Why it matters
When you assess an adult with ID, add quick grip and leg strength tests. Low scores flag both health and cognitive risk. If strength is low, refer to high-effort resistance programs like Diemer et al. (2023) showed work in group homes. Stronger bodies may support sharper minds and longer independence.
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02At a glance
03Original abstract
BACKGROUND: Physical exercise seems to improve cognitive abilities at different physiological levels. Numerous studies have examined the relationship between physical fitness (PF), physical activity and cognition among populations without intellectual disabilities (ID), but very few have addressed this question with respect to people with ID. This study aimed to determine the correlation between intelligence quotient (IQ) and factors related to PF in healthy adults with ID. METHODS: A multicentre cross-sectional study was conducted in 91 individuals with ID. All participants were assessed with the K-BIT tests and the following test items from the SAMU DIS-FIT Battery: body mass index, handgrip strength (HGS), leg strength, dynamic balance and physical endurance. RESULTS: Significant differences between men and women were tested by multiple regression. IQ was found to be statistically related to HGS and leg strength, with a medium effect size. Statistical relationships were also found between sex and physical endurance, with a medium effect size, and HGS, with a large effect size. CONCLUSIONS: The study results highlight relationships between the variables of muscular strength and the participants' IQ. Further studies with experimental designs are needed to enhance the understanding of the relationships between PF and cognition in persons with ID.
Journal of intellectual disability research : JIDR, 2021 · doi:10.1111/jir.12883