Post-exercise heart rate recovery in individuals with spinal cord injury.

STUDY

DESIGN

Prospective comparison of spinal cord injured (SCI) subjects and ambulatory subjects.

OBJECTIVES

To determine the effects of the presence and level of SCI on heart rate recovery (HRR).

SETTING

Outpatient SCI center.

METHODS

HRR was determined in 63 SCI subjects (26 with tetraplegia, 22 with high-level paraplegia, 15 with low-level paraplegia) and 26 ambulatory subjects. To adjust for differences in heart rate reserve between groups (HR peak minus HR rest), HRR was also 'normalized' to a range of 1 at peak heart rate and to 0 at 8 min, and the shapes of HRR curves were compared.

RESULTS

Although absolute HRR was similar between high- and low-level paraplegia, it was significantly more rapid in participants with paraplegia at 2, 5 and 8 min after exercise than in those with tetraplegia (39+/-14 vs 29+/-14 b.p.m., P<0.05; 51+/-14 vs 33+/-16 b.p.m., P<0.01 and 52+/-16 vs 36+/-17 b.p.m., P<0.01, respectively). HRR among ambulatory subjects was more rapid than among those with tetraplegia at all time points in recovery. However, when normalized for heart rate reserve, HRR was significantly more rapid in tetraplegic subjects (P<0.001 vs paraplegia and ambulatory subjects).

CONCLUSION

In SCI, HRR is strongly associated with the peak exercise level and peak heart rate achieved during exercise testing.