Cardiac autonomic function during submaximal treadmill exercise in adults with Down syndrome.
Adults with Down syndrome show sluggish heart-rate rise and high stress-system drive during medium treadmill walking.
01Research in Context
What this study did
The team put adults with Down syndrome on a treadmill. They walked at a steady, medium pace. Sensors tracked heart rate and nervous-system signals. A comparison group of adults without Down syndrome did the same walk.
What they found
The DS group’s heart rate rose more slowly. Their fight-or-flight system stayed stuck on high. Controls showed a quick heart climb and calm recovery. The blunted response signals weak autonomic flexibility.
How this fits with other research
Agiovlasitis et al. (2010) saw the same dull autonomic reaction, but used a tilt table instead of walking. V et al. now show the pattern holds during real movement.
Hu et al. (2013) added vascular data: arteries in DS also stiffen less after exercise. Together the papers map a heart-and-blood-vessel system that can’t ramp up or cool down normally.
Lemons et al. (2015) look like they disagree: one 20-min treadmill walk improved thinking skills in DS. The catch is outcome direction. Their study measured cognition, not heart stress, and used a single snapshot. The cardiovascular risk shown by V et al. is still there; it just doesn’t cancel the short-term brain boost.
Why it matters
If you run exercise programs for adults with DS, treat “moderate” treadmills as light for them. Watch for slow heart rise, long recovery, and signs of overwork. Build longer warm-ups, lower speeds, and frequent pulse checks. Pair the session with cognitive tasks if you want the bonus shown by J et al., but never skip cardiovascular monitoring.
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02At a glance
03Original abstract
This study determined whether the cardiac autonomic function of adults with Down syndrome (DS) differs from that of nondisabled persons during submaximal dynamic exercise. Thirteen participants with DS and 12 nondisabled individuals performed maximal and submaximal treadmill tests with metabolic and heart rate (HR) measurements. Spectral analysis of HR variability was performed on the last 256 consecutive R-R intervals obtained under the following conditions: (1) rest, (2) submaximal treadmill exercise (at constant relative intensity below the ventilatory threshold) and (3) recovery. Participants with DS presented lower chronotropic response than those without DS to peak and submaximal exercise (p<0.05). Nevertheless, the fractional utilization of peak HR during treadmill walking was similar between groups (∼60% peak HR). Even though there were no between-group differences at rest or during recovery, the participants with DS showed a higher LF/HF ratio during exercise (p<0.05). Similarly, the LF power of participants with DS during exercise was greater than that of nondisabled participants (p<0.05). In contrast, both groups exhibited similar HF power at each physiological condition. In conclusion, these findings suggest that adults with DS demonstrate appropriate vagal withdrawal, but heightened sympathetic modulation of HR variability at ∼60% of their peak HR. Despite this, the absolute change in HR from rest to exercise was attenuated in these individuals compared to persons without disabilities. This indicates that DS may be associated with poor cardiac responsiveness to changes in autonomic modulation during exercise at intensities below the ventilatory threshold.
Research in developmental disabilities, 2011 · doi:10.1016/j.ridd.2010.12.028