Lower-extremity functional electrical stimulation decreases platelet aggregation and blood coagulation in persons with chronic spinal cord injury: a pilot study

Abstract

Background: Individuals with spinal cord injury (SCI) develop premature cardiovascular disease. Regular exercise reduces the incidence and symptoms of cardiovascular disease in able-bodied individuals; these salutary effects of exercise have not been documented in persons with SCI.

Objective: To evaluate the effects of functional electrical stimulation leg cycle ergometry (FES-LCE) exercise training on platelet aggregation and blood coagulation in persons with SCI.

Participants: Subjects (n=14) with stable chronic (>1 year) paraplegia (T1-T10) or tetraplegia (C4-C8).

Methods: Blood samples were collected before and after the first and eighth sessions (2 sessions per week for 4 weeks) of FES exercise.

Results: Platelet aggregation was inhibited by 20% after the first session and by 40% (P < 0.001) after the eighth session. Thrombin activity was unchanged after the first session (10.7 +/- 0.85 s to 10.43 +/- 0.56 s) and decreased after the eighth session (12.5 +/- 1.98 s to 11.1 +/- 1.7 s; P < 0.0003). Antithrombin III activity increased after the first (103.8% +/- 8.9% to 110% +/- 6.9%; P < 0.0008) and eighth sessions (107.8% +/- 12.1% to 120.4% +/- 13.1%; P < 0.0001). Cyclic adenosine monophosphate increased after the first (9.9% + 2.5% to 15.8% +/- 3%; P < 0.001) and eighth sessions (17.8% +/- 4.2% to 36.5% +/- 7.6%; P < 0.0001). After the eighth session, factors V and X increased significantly (88% +/- 27% to 103% +/- 23%, P < 0.0001; 100% +/- 40% to 105% +/- 7%, P < 0.01, respectively); factors VII and VIII and fibrinogen did not change significantly. A significant reduction in platelet activation/aggregation was demonstrated in response to FES-LCE. The decrease in thrombin level was caused by the simultaneous increase in antithrombin activity.

Conclusion: These findings provide new insight into the potential protective effects of FES-LCE against the risk of cardiovascular disease.

Figure 1

Effect of FES exercise training on thrombin. Blood samples for thrombin levels were collected before and after the first and eighth FES exercise sessions. Results are expressed as means ± SDs.

Figure 2

Effect of FES exercise on AT activity. The percent activity of AT III was determined before and after the first and eighth FES exercise sessions for comparison. AT activity post–FES exercise was compared after the first and eighth sessions. Results are expressed as means ± SDs.

Figure 3 and 4

Determination of activity of coagulation factors V and X. Results are expressed as means ± SDs.

Figure 5

Effect of FES exercise on cAMP. The formation of cAMP was determined by adding 100 nM PGI₂ to platelet suspensions. All comparisons (eg, before vs after exercise, after the first and eighth sessions, before exercise at each time point, and after exercise at each time point) were significant. Results are expressed as means ± SDs.