Effects of functional electrical stimulation-induced lower extremity cycling on bone density of spinal cord-injured patients

Abstract

Spinal cord-injured (SCI) patients are at increased risk for fractures secondary to neurogenic osteoporosis. Earlier research claimed physical conditioning resulted in a decreased incidence or reversal of neurogenic osteoporosis. This study evaluated the effects of functional electrical stimulation-induced lower extremity cycling (FESILEC) on the bone densities of SCI patients using dual-energy x/ray absorptiometry (DEXA). The study consisted of 12 healthy male SCI patients, aged 23 to 46 (x +/- SD, 34 +/- 6) yr. The patients were post-traumatic, complete, spastic SCI; time postinjury ranged from 2 to 19 (9.7 +/- 5.1) yr. Patients participated in a three-phase training program. Phase 1 consisted of quadriceps strengthening. Phase 2 consisted of progressive sequential stimulation of quadriceps, hamstrings, and gluteal muscles, achieving a rhythmical pedaling motion on the REGYS I ergometer. Phase 3a consisted of 30-min FESILEC sessions. DEXAs were done at baseline and at completion of Phase 3a and Phase 3b. Bone densities were done of the lumbar spine levels 2-4 (L2-4), bilateral trochanters (T), Ward's triangles (WT) and femoral necks (FN). Baseline bone density indicated no difference between L2-4 of ambulatory males and SCI males. Baseline values obtained for T, WT, and FN were, respectively, 71, 82, and 79% of ambulatory values. Results after completion of the Phase 3a training program indicated no statistically significant difference compared with baseline values. There was, however, a positive trend in the lumbar spine post-Phase 3a (L2-4, P=0.056). Eight patients continued the exercise program, using a combination of upper and lower extremity cycling (Phase 3b) for a longer period of time (25 +/- 9 wk). DEXAs done after Phase 3b indicated no change relative to baseline data or data post-Phase 3a. In conclusion, although FESILEC did not significantly increase bone density in the hip parameters of chronic SCI patients, a positive trend was observed in the lumbar spine. Further research with acute intervention, such as FESILEC during the first few months post-SCI, is warranted to further evaluate a treatment regimen to prevent or reduce neurogenic osteopenia.