Increasing Strength and Flexibility of Adults Diagnosed with Autism Spectrum Disorder and an Intellectual Disability through a Strength and Conditioning Program

Background:   While the prevalence of autism spectrum disorder (ASD) continues to rise, research focused on the adult population remains limited. This is troublesome as current trajectories report poor adult outcomes related to an ASD diagnosis, especially in the presence of an intellectual disability (ID). Though these poor adult outcomes are often attributed to the core symptoms of ASD, health and lifestyle factors should also be considered. For example, during childhood and adolescence, individuals with ASD have lower levels of physical activity compared to typically developing peers, with participation in sedentary behaviours increasing with age. This trend is evidenced by poor measures of fitness, and increased rates of obesity and secondary health conditions within this population. Therefore, an adapted physical exercise (APEX) program focused on strength and conditioning may be a viable intervention strategy to alter current health patterns and improve adulthood trajectories for individuals with ASD and an ID.

Objectives:   To assess the impact of a 12-week APEX program on heart rate, blood pressure, flexibility, and isometric strength in adults with ASD and an ID.

Methods:   Fourteen adults with ASD and an ID (age range = 18-62 years; 2 females; IQ scores from previous clinical assessment = 20 to 70) participated in an APEX program twice per week for twelve weeks. Each APEX session was 90-minutes in length and consisted of cardiovascular training on a stationary bike, strength training using weight machines and free weights, and sports and games. All participants completed fitness testing pre-, mid-, and post-program which included: (1) resting heart rate and blood pressure, (2) the sit and reach test as a measure flexibility, and (3) a measure of isometric strength for the upper and lower body.

Results:   Significant improvements in upper body strength of the right (F[1,10] = 5.058, p = 0.049, ω² = 0.25) and left bicep (F[1,10] = 8.109, p = 0.017, ω² = 0.37) were found from pre- (right bicep: M = 21.61 lb.; left bicep: M = 20.62 lb.) to post-testing (right bicep: M = 28.83 lb.; left bicep: M = 29.82 lb.). Significant increases were also found from pre- (M = 10.72 cm) to post-testing (M = 16.63 cm) for flexibility (F[1,11] = 5.690, p = 0.036, ω² = 0.27). No significant changes were found for resting heart rate, systolic or diastolic blood pressure, or lower body strength (p > 0.05).

Conclusions:   Twelve weeks of APEX programming provided a significant increase in upper body strength, as well as flexibility in adults diagnosed with ASD and an ID. While the remaining fitness measures did not experience significant changes, the observed improvement in lower body strength (right quadricep: 18% increase, ω² = 0.16) has potential to yield practical health benefits for participants. Therefore, an APEX program focused on strength and conditioning is a worthwhile service option for adults with ASD and an ID as it elicits improvements in measures of fitness, which may translate into improved outcomes in adulthood.