Effects of Functional Electrical Stimulation-Induced Lower Extremity Cycling on Bone Density of Spinal Cord-Injured Patients1

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.

Intensive exercise may preserve bone mass of the upper limbs in spinal cord injured males but does not retard demineralisation of the lower body

“…Hip region BMD in our SCI group was 67, 66 and 63% that of the control group, for FN, WT and T, respectively. These ®gures are slightly lower than those found by BeDell et al 21 and Szollar et al, 36 but do support the extent of bone loss at these sites in our SCI individuals.…”

“…21 ± 23 However, results of load-bearing exercise in a microgravitational environment have been equivocal. 11,12,20,21,24,25 The purpose of this study was to compare bone mineral density of the total body, upper limbs, lower limbs, hip, and spine regions in a group of very active spinal cord injured adult males with values obtained in active able-bodied controls, carefully matched for age, height, and weight.…”

DEXA: a practical and accurate tool to demonstrate total and regional bone loss, lean tissue loss and fat mass gain in paraplegia

“…9,11 Reductions in hip region BMD were large, with the average femoral neck BMD being 74% that of agematched controls (LUNAR database). BeDell et al 29 (DEXA) found 79% BMD for the femoral neck in a group of paraplegics of similar duration of injury. This places our paraplegics in a high risk category for fracture.…”

Physiological effects of lower extremity functional electrical stimulation in early spinal cord injury: lack of efficacy to prevent bone loss

“…[4][5][6][7] Clinical and experimental studies indicate that neuromuscular electrical stimulation can both affect and effect changes in muscle fibre contractile properties 4,8 and metabolism, 9,10 as well as responses at physiological 5,6 and functional levels. Although well studied, 7,[11][12][13] there is conflicting evidence about the efficacy of electrically evoked muscle activation in the stimulation of bone metabolism (bone formation and/or reduction of bone loss), and the clinical role of functional electrical stimulation (FES) in the treatment of osteoporosis resulting from neurological damage. The reason for this conflict may be that bone metabolic abnormalities may be time dependent [14][15][16] or as-yet-unexplained factors affect the osteogenic response to mechanical strain.…”