Intelligence quotient (IQ) in individuals with intellectual disabilities is significantly associated with muscle strength, both in the lower and upper body, according to new research.

The study published in the Journal of Intellectual Disability Research looked at the association between physical fitness, body mass index (BMI) and IQ in individuals with intellectual disabilities.

Numerous studies have examined the relationship between physical fitness, physical activity and cognition among populations without intellectual disabilities, but very few have addressed this question with respect to people with intellectual disabilities. This study aimed to determine the correlation between IQ and factors related to physical fitness in healthy adults with intellectual disabilities.

It found that IQ was found to be statistically related to handgrip strength and leg strength, with a medium effect size. Statistical relationships were also found between sex and physical endurance, with a medium effect size, and handgrip strength, with a large effect size.

There was a significant association observed between IQ and muscle strength, both in the lower and in the upper body. However, no such relationship was found with physical endurance, dynamic balance or BMI. 

Can learning abilities be improved by physical conditioning?

The multicentre cross-sectional study was conducted in 91 individuals with intellectual disabilities, of whom 26 were female and 65 were male. Their mean age was 38.90 years (SD = 9.72).

All met the following inclusion criteria: (1) they had been diagnosed by the competent administration as presenting mild or moderate ID; (2) they were resident in a care institution; (3) they presented medical authorisation of aptitude for sports activities in order to avoid risks to their health during the physical tests; (4) when the study was performed, they were not regularly participating in sports activities or physical exercise programmes. 

All participants were assessed with the Kaufman Brief Intelligence Test and the following test items from the  SAMU Disability Fitness Battery: body mass index, handgrip strength, leg strength, dynamic balance and physical endurance.

The authors said that although the evidence reported is a good starting point, further study is needed to clarify three fundamental questions regarding the relationship between cognition and physical fitness:

  • Does better physical fitness result in improved cognitive performance?
  • Which elements of physical fitness are more strongly associated with cognition?
  • From the above, what consequences would changes in physical fitness have on the brain structures related to cognitive abilities and capacities, especially in people with intellectual disabilities?

If these questions are satisfactorily resolved, physical activity programmes can be developed to improve the cognitive skills of people with intellectual disabilities. Consequently, experimental, longitudinal studies should be designed and implemented to determine causal relationships between these variables, and thus clarify the relationship between physical fitness and cognitive ability in people with intellectual disabilities.

Ultimately, therefore, we wish to answer the question: can learning abilities of people with  intellectual disabilities be improved by physical conditioning?