Exercise training does not attenuate cardiac atrophy or loss of function in individuals with acute spinal cord injury: a pilot study

Arch Phys Med Rehabil, 2023 · DOI: 10.1016/j.apmr.2022.12.001 · Published: June 1, 2023

Spinal Cord Injury Cardiovascular Science Rehabilitation

Simple Explanation

This study investigated whether exercise training could prevent heart muscle loss and decreased function in people with recent spinal cord injuries (SCI). Two types of exercise were tested: arm rowing alone and arm rowing combined with electrical stimulation of leg muscles. The study found that the longer the time since the spinal cord injury, the more the heart muscle decreased in size and function. Exercise training did not stop this decline, even when using electrical stimulation to engage leg muscles during rowing. These findings suggest that regular aerobic exercise, as commonly practiced in rehabilitation, may not be enough to prevent heart problems after a spinal cord injury. Other interventions may be needed to protect heart health in this population.

Study Duration

6 Months

Participants

27 (5 women, 22 men) <24 months post SCI

Evidence Level

Randomized Controlled Trial

Key Findings

1
Time since injury was significantly associated with a continuous decline in cardiac structure and systolic function, specifically, a reduction in left ventricular mass, internal diameter during systole and diastole, as well as cardiac output, and left ventricular percent shortening.
2
Exercise (arm rowing alone or combined with electrical stimulation) did not differentially impact the decline in cardiac structure and function associated with time since injury.
3
Individuals in the FES group experienced a significant increase in cardiorespiratory fitness, but this did not translate to changes in the associations between left ventricular atrophy and time since injury.

Research Summary

This study examined the effects of arm-only rowing (AO) and functional electrical stimulation (FES) rowing on cardiac structure and function in individuals with subacute spinal cord injury (SCI). The results indicated that time since injury (TSI) was significantly associated with a decline in cardiac structure and systolic function, including reductions in left ventricular mass (LVM), internal diameters, cardiac output, and left ventricular percent shortening. Contrary to the hypothesis, neither AO nor FES rowing attenuated the loss of cardiac structure or function associated with increased TSI, suggesting that traditional aerobic exercise may not be sufficient to prevent cardiac decline in individuals with subacute SCI.

Practical Implications

Further interventions needed

The study suggests that current rehabilitative aerobic exercise practices are not enough to prevent cardiac decline in individuals with subacute SCI, highlighting the need for further interventions.

Importance of early intervention

The subacute phase of injury recovery may be a critical time to implement therapeutic interventions to prevent irreversible atrophy of the myocardium and loss of ventricular compliance.

Separate assessment of CVD risk factors

Change in heart size does not correlate with change in cardiorespiratory fitness in individuals with subacute SCI, hence future research should examine the two cardiovascular disease risk factors separately.

Study Limitations

1
The study had very few measurements that were below the reference range for people without SCI.
2
The longitudinal analysis did not identify an asymptote in the myocardial reductions.
3
The small number of participants in the AO (n=6) was unlikely to show similar increases in VO2peak as other studies examining cardiorespiratory fitness programs and this design resulted in a low power (8-24%) to detect significant differences between groups using two main outcome measures (LVM and VO2peak).

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