Effects of FES‐Rowing Exercise on the Time‐Dependent Changes in Bone Microarchitecture After Spinal Cord Injury: A Cross‐Sectional Investigation

Abstract

Disuse osteoporosis is a serious, secondary consequence of spinal cord injury (SCI). Numerous pharmacological and exercise therapies have been implemented to mitigate bone loss after SCI. However, these therapies have not been shown to improve bone density, potentially because of insufficient duration and magnitude of loading and/or inability of imaging modalities to capture changes in bone microarchitecture. In this cross-sectional study, we evaluated bone microstructure of the distal tibia and radius using HR-pQCT in men with SCI (N = 13) who regularly trained with functional electrical stimulation-(FES-) rowing. We aimed to determine whether the amount of FES-rowing (total distance rowed and peak foot force) and/or time since injury (TSI) predict bone loss after SCI. We assessed volumetric density of the total, cortical, and trabecular compartments, cortical thickness, and trabecular thickness. Using linear regression analysis, we found that TSI was not associated with any of the tibial bone metrics. In fact, none of the variables (TSI, total distance rowed, and peak foot force) independently predicted bone loss. Using stepwise regression, when all three variables were considered together, we found a strong prediction for trabecular microstructure (trabecular vBMD: R 2 = 0.53; p = 0.06; trabecular thickness: R 2 = 0.72; p < 0.01), but not cortical bone metrics. In particular, trabecular vBMD and thickness were negatively associated with TSI and positively associated with distance rowed. Foot force contributed markedly less to trabecular bone than distance rowed or TSI. Our results suggest that regular FES-rowing may have the capacity to alter the time-dependent bone negative effects of SCI on trabecular bone density and microstructure.

Selective neural stimulation methods improve cycling exercise performance after spinal cord injury: a case series

“…Due to these inherent limitations, significant improvements in physiological markers of fitness such as bone density, which is load-dependent and may require longer exercise durations against higher resistances, have not been well reproduced with electrical stimulation systems [14][15][16][17]. Many of the significant physiological improvements that have been cited typically come only after extensive long-term training regimens, which may not be a feasible or appealing commitment to most people with paralysis.…”

Effect of hybrid FES exercise on body composition during the sub-acute phase of spinal cord injury

“…This leads to a rapid and significant bone loss of 45% in the pelvis and 25% in the legs [46]. It has been previously shown that those with a longer PLOS ONE time since injury have relatively lower trabecular BMD and thickness and FESRT coupled with pharmacotherapy can counter the negative time-dependent effects of SCI on bone density and microstructure [31]. Our current results indicate that early application of sufficient load to sub-lesional bones via FESRT without pharmacotherapy can have a significant effect in preserving BMD, specifically in the involved pelvic region compared to SOC.…”

“…Studies in able-bodied individuals indicate that improved body composition [ 23 , 24 ] and cardiovascular fitness [ 25 , 26 ] directly relate to exercise intensity. In SCI, higher intensity exercise is more effective in increasing peak oxygen uptake [ 27 – 29 ] and may be associated with higher resultant lean mass and bone density [ 16 , 30 , 31 ]. Indeed, hybrid FES exercise at higher exercise intensities holds promise to mitigate adiposity, sarcopenia, and metabolic dysregulation [ 32 – 35 ].…”

The Effects of Exercise and Activity-Based Physical Therapy on Bone after Spinal Cord Injury

“…First, higher total work output was associated with greater BMD gain. For example, Lambach et al [ 106 ] reported that a higher magnitude of loading and more weekly training sessions were both associated with less trabecular vBMD loss at the proximal femur in persons that were undergoing FES rowing, and Draghici et al [ 142 ] reported that total distance rowed and peak foot reaction force were positively associated with the preservation of the distal tibia trabecular thickness in persons that were undergoing FES rowing, when these factors and SCI duration were incorporated into stepwise regression models. Similarly, Bloomfield et al [ 96 ] reported that distal femur aBMD was improved (+17.8% vs. the baseline) in a subgroup of persons who achieved power outputs >18 watts (W) during FES cycling, while aBMD was not improved in those with lower power output (<12 W, BMD change +0.2%) or in non-exercising controls (−2.3% vs. the baseline) and Frotzler et al [ 134 ] reported that FES cycling improved the total and trabecular vBMD at the distal femur with participants averaging ~18 W power output.…”