Metabolic responses to arm ergometry and functional neuromuscular stimulation

Abstract

The hips and lower extremities of four complete paraplegic male subjects (T-6, T-7, T-8, and T-11) were stimulated with functional neuromuscular stimulation (FNS) via transcutaneous intramuscular electrodes (20 mA, 0-150 pulse width, and 20 Hz) . Cardiopulmonary (CP) and/or cardiovascular (CV) responses were measured during maximal (seated) arm ergometry (AE), FNS, and FNS + AE . Subjects' lower extremities were stimulated with a 2 s walking cycle via a microprocessor computer. Data were collected with a SensorMedic MMC Horizon (VO 2 and VCO2 at STPD and VE at BPTS). The mean MET level (1 MET = 3.5 ml 0 2 /kg/min) during FNS was 4 .8. Mean METS during FNS + AE was 10 .3 and mean METS for AE was 7.2 . Mean lactic acid (LA) after FNS, AE, and FNS + AE was 73 mg percent, 77 mg percent and 115 mg percent respectively. Respiratory exchange ratio (RER) (VCO2 /VO2 ) was >1 .2 during the first 2 to 5 min of FNS but decreased to <1 .0 during the second 5 min of FNS . Steady state V02 and RER <1 .0 indicated a FNS transition from anaerobic to aerobic metabolism . Subject T-11 had CV limitations during FNS and FNS + AE due to excessive LA from FNS (115 mg percent) . Ventilatory (VE) responses during AE, FNS, and FNS + AE were consistent with V0 2 ; and mean maximal VE and V02 for subjects T-6, T-7, and T-8 during FNS + AE was greater than 90 percent of that observed in sedentary normals . The aerobic and anaerobic capacities of paraplegic subjects is primarily limited by available muscle mass rather than impaired CV or CP function.

Health and Fitness Benefits of Functional Electrical Stimulation-Evoked Leg Exercise for Spinal Cord–Injured Individuals

“…Further empirical evidence from crossover studies supported the viewpoint that combined upper body voluntary exercise and FES-evoked leg exercise produced enhanced metabolic responses, which included higher peak VO 2 56,109-111 ; increased posttraining measurements of HR, VO 2 , VE, and Q 67, 99,112 ; larger SV; greater arteriovenous oxygen extraction 98 ; and increased peak power output. 42 The level of whole-body metabolism (METS) during FES alone was less than 50% of that observed during arm plus leg exercise, 113 and blood-borne lactic acid was also highest during hybrid exercise likely due to the larger muscle mass involved in such exercise. 113 In a self-controlled randomized trial of SCI individuals who performed FES-assisted rowing, Laskin and co-workers 114 observed that arm plus leg rowing evoked sig-nificantly higher VO 2 compared to FES leg stimulation only or voluntary manual rowing only.…”

Walking after incomplete spinal cord injury using an implanted FES system: A case report

“…Functional electrical stimulation (FES) has been used therapeutically to improve the health and independence of persons with paraplegia by activating and coordinating paralyzed lower-limb muscles, improving cardiovascular fitness [5], and decreasing the risk of diabetes [6], as well as reducing osteoporosis [7] * without adverse effects on the insensate joints [8]. Preliminary studies suggest that FES exercise and weight bearing also reduce the risk of pressure sores by improving tissue oxygen levels, increasing muscle bulk, and altering seated pressure distribution [9].…”

Experiencing Functional Electrical Stimulation Roots on Education, and Clinical Developments in Paraplegia and Tetraplegia With Technological Innovation

“…Referring to FES treadmill tetraplegic gait, there is a definite increase in oxygen consumption thus improving cardiovascular function (Fig. A) . For FES‐based paraplegic gait, oxygen consumption increases at the beginning, reaches a steady state, and decreases toward values of the beginning of gait within a short interval after end of gait.…”