Charles F. Kunkel

Increasing muscle mass in spinal cord injured persons with a functional electrical stimulation exercise program

OBJECTIVE To determine the magnitude of changes in muscle mass and lower extremity body composition that could be induced with a regular regimen of functional electrical stimulation (FES)-induced lower-extremity cycling, as well as the distribution of changes in muscle mass among the thigh muscles in persons with spinal cord injury (SCI). STUDY DESIGN Thirteen men with neurologically complete motor sensory SCI underwent a 3-phase, FES-induced, ergometry exercise program: phase 1, quadriceps strengthening: phase 2, progressive sequential stimulation to achieve a rhythmic pedaling motion (surface electrodes placed over the quadriceps, hamstrings, and gluteal muscles); phase 3, FES-induced cycling for 30 minutes. Participants moved from one phase to the next when they met the objectives for the current phase. MEASURES Computed tomography of legs to assess muscle cross-sectional area and proportion of muscle and adipose tissue. Scans were done at baseline (before subjects started the program), at first follow-up, typically after 65.4+/-5.6 (SD) weekly sessions, and at second follow-up, typically after 98.1+/-9.1 sessions. RESULTS Increases in cross-sectional areas were found in the following muscles: rectus femoris (31%, p<.001). sartorius (22%, p<.025), adductor magnus-hamstrings (26%, p<.001), vastus lateralis (39%, p = .001), vastus medialis-intermedius (31%, p = .025). Cross-sectional area of adductor longus and gracilis muscles did not change. The ratio of muscle to adipose tissue increased significantly in thighs and calves. There was no correlation among the total number of exercise sessions and the magnitude of muscle hypertrophy. CONCLUSIONS Muscle cross-sectional area and the muscle to adipose tissue ratio of the lower extremities increased during a regular regimen of 2.3 FES-induced lower extremity cycling sessions weekly. The distribution of changes was related to the proximity of muscles to the stimulating electrodes.

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

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), Wards 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.

Changes in gas exchange kinetics with training in patients with spinal cord injury

We examined the ability of patients with spinal cord injury to undergo adaptations to chronic exercise training (cycle ergometry) invoked by functional electrical stimulation (FES) of the legs. Nine such patients performed incremental and constant work rate exercise before and after exercise training. Exercise sessions averaged 2.1 +/- 0.4/wk, and consisted of 30 min/session of continuous FES recumbent cycling with increasing work rate as tolerated. Peak VO2 and peak work rate significantly improved with training. Peak VO2 was significantly correlated with peak heart rate both before and after training (r = 0.97 pre and 0.85 post, P < 0.01 for both). The time course of the VO2, VCO2 and VE responses to constant-load exercise (unloaded cycling) and in recovery (mean response time MRT) were very long prior to training, and became significantly faster following training. However, there was no correlation between percentage improvement in either MRTon or MRToff for VO2 and the percentage increase in peak VO2. Exercise tolerance in these patients with spinal cord injury appears to be a direct function of the ability to increase heart rate. Further, exercise training can elicit significant improvements in both exercise tolerance and in gas exchange kinetics, even when performed only twice per week. However, these improvements may be accomplished by different mechanisms.

Gas exchange kinetics during functional electrical stimulation in subjects with spinal cord injury

We examined the kinetics of VO2, VCO2, and VE following the onset of unloaded leg cycling, and in recovery, in six patients with spinal cord injury (SCI). Exercise was produced by functional electrical stimulation (FES) of the quadriceps, hamstrings, and gluteal muscles. End-exercise VO2 (1.03 +/- 0.16 l.min-1), VCO2 (1.20 +/- 0.22 l.min-1) and VE (41 +/- 10 l.min-1) were elevated compared to values typically seen in healthy ambulatory subjects performing similar unloaded cycling. Mean response times for the on transients (MRTon) were both long and variable across subjects for VO2 (165 +/- 62 s), VCO2 (173 +/- 58 s), and VE (202 +/- 61 s). Recovery kinetics showed much less intersubject variability, and for five of six subjects were faster than the equivalent exercise MRT for all three variables (MRToff for VO2 of 103 +/- 28 s, VCO2 136 +/- 20 s, and VE 144 +/- 34 s), but P > 0.05 for all three. Size of the O2 deficit (1.96 +/- 0.90 l) and end-exercise lactate (7.05 +/- 1.65 mmol.l-1) were similar to values reported for healthy sedentary subjects performing maximal voluntary exercise, but the end-exercise heart rate (102 +/- 16 bpm) was lower than expected for this intensity of exercise. In conclusion, FES-induced unloaded cycling leads to exaggerated responses of pulmonary gas exchange and long time constants in patients with SCI. The delayed kinetics may be due in part to a blunted increase in heart rate in addition to severe deconditioning.

Effects of Exercise Training on Calf Tissue Oxygenation in Men With Intermittent Claudication

To determine the effects of exercise training on calf tissue oxygenation in men with peripheral arterial disease and intermittent calf claudication.

Preamputation Evaluation of Lower-Limb Skeletal Muscle Perfusion with H2 15O Positron Emission Tomography

Scremin OU, Figoni SF, Norman K, Scremin AME, Kunkel CF, Opava-Rutter D, Schmitter ED, Bert A, Mandelkern M: Preamputation Evaluation of Lower-Limb Skeletal Muscle Perfusion with H215O Positron Emission Tomography. Objective:To establish whether muscle blood flow (MBF) measurements with 15O-water positron emission tomography could reliably identify patients with critical limb ischemia and detect and quantify a distal deficit in skeletal MBF in these cases. Design:15O-water positron emission tomography scans were performed at rest or during unloaded ankle plantar and dorsiflexion exercise of the diseased leg in 17 subjects with leg ischemia or on a randomly selected leg of 18 age-matched healthy control subjects. TcPO2 was evaluated with Novametrix monitors and perfusion of skin topically heated to 44°C and adjacent nonheated areas with a Moor Instruments laser Doppler imaging scanner. Results:The enhancement of MBF induced by exercise was significantly lower in ischemic than in normal legs, and the sensitivity and specificity of this phenomenon were similar to those of laser Doppler imaging or TcPO2 in identifying ischemia subjects. In addition, the exercise MBF deficit was predominant at the distal-leg levels, indicating the ability of the technique to help determine the correct level of amputation. Conclusions:Skeletal MBF of legs with severe ischemia can be detected accurately with 15O-water positron emission tomography and could add valuable information about viability of skeletal muscle in the residual limb when deciding the level of an amputation.

Behavioral Interventions for Antipsychotic Medication–Associated Obesity: A Randomized, Controlled Clinical Trial

OBJECTIVE To demonstrate the effectiveness of a Diabetes Prevention Program-inspired 12-month behavioral intervention for patients with severe mental illness (SMI) and medication-associated obesity. METHOD This randomized, controlled, parallel, superiority study screened 225 volunteers from November 2005 to August 2008 at the VA Greater Los Angeles Healthcare System. 122 outpatients with DSM-IV-diagnosed SMI taking antipsychotic medications who had ≥ 7% weight gain or body mass index (BMI) > 25 were randomized by computer-generated number to Lifestyle Balance treatment intervention (n = 60) or usual care control (n = 62) groups. Clinical raters were masked to randomization. Treatment intervention included weekly classes and individual counseling for 8 weeks, food and exercise diaries, rewards, caregiver consultations, and monthly booster classes and counseling for 1 year. Controls received self-help materials and visited at equivalent intervals without formal classes or counseling. Outcomes were changes in anthropometric measurements, psychiatric symptoms, health knowledge, and glucose, hemoglobin A1c, and lipid levels. RESULTS Our intention-to-treat analysis found significant differences in predicted trajectory of mean weight change between the groups over 12 months (P < .01), with treatment participants expected to lose an average 4.6 kg, while control participants would gain an average 0.6 kg. BMI and body fat percentage followed the same pattern. Both groups demonstrated statistically significant improvements in health knowledge quiz scores over time (P = .006), without significant difference between groups. CONCLUSIONS Treatment was more effective than usual care control in treating medication-associated obesity, independent of SMI diagnosis, antipsychotic medication, and knowledge gained, suggesting that behavioral interventions are effective in SMI patients. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT00344500.

Scanning laser-doppler imaging of leg-and foot-skin perfusion in normal subjects : Analysis of age, gender, site, and laser-type effects

Kunkel CF, Figoni SF, Baumgarten JM, Carvalho CM, Kim HS, Oshiro RL, Zirovich MD, Scremin OU, Scremin AME: Scanning laser-Doppler imaging of leg- and foot-skin perfusion in normal subjects: analysis of age, gender, site, and laser-type effects. Am J Phys Med Rehabil 2007;86:262–271. Objectives:To report normal values of skin perfusion in healthy subjects in three age groups using a laser Doppler imager; to determine differences attributable to gender, age, site, and use of red or near-infrared lasers; and to correlate transcutaneous oxygen with laser flux values Design:Flux and transcutaneous oxygen were measured at ten sites in the lower extremity in 60 subjects from three age groups. Heated and unheated sites were scanned with red and near-infrared lasers. Results:Heat hyperemia was prominent at all sites. Small, statistically significant mean ± SD differences were found between heated and nonheated sites for the red and near-infrared lasers (P = 0.02). All flux ratios were independent of gender but were higher in the oldest group. Plantar sites demonstrated higher flux in unheated areas and lower flux ratios compared with leg sites. Transcutaneous oxygen did not correlate significantly with flux for either laser type. Conclusions:Scanning laser-Doppler imaging flux values provide a reference for identifying patients at risk for tissue ischemia and poor healing potential caused by impaired circulatory reserve in the legs and distal feet. The lack of correlation between flux and transcutaneous oxygen in healthy individuals suggests that they measure different physiologic processes.

Preamputation Evaluation of Limb Perfusion with Laser Doppler Imaging and Transcutaneous Gases

We studied 31 subjects with severe leg ischemia and 29 age-matched nonischemic control subjects to compare preamputation assessments of leg ischemia using laser Doppler imaging (LDI), transcutaneous partial pressure of oxygen (TcPO(2)), and transcutaneous partial pressure of carbon dioxide (TcPCO(2)). TcPO(2) and TcPCO(2) were evaluated with Novametrix Medical Systems, Inc, monitors (Wallingford, Connecticut) and perfusion (flux) of skin topically heated to 44 degrees C, and adjacent nonheated areas were evaluated with a Moor Laser Doppler Imager (Moor Instruments, Ltd; Devon, England). LDI flux of heated areas, its ratio to nonheated areas, and TcPO(2) (not TcPCO(2)) were lower in ischemic subjects than in control subjects. LDI flux ratio performed better than TcPO(2) in identifying ischemia, with fewer false positive and false negative results. Moreover, LDI flux of heated skin detected a proximal to a distal gradient of perfusion in ischemic subjects, while TcPO(2) did not. LDI was superior to TcPO(2) in discriminating correctly between ischemic and nonischemic skin. The results suggest that an LDI ratio below 5 indicates nonviable skin.

Ergometric Performance During Exercise Training in Men With Intermittent Claudication

To determine and describe changes in weekly work, power, exercise times, and recovery times during an exercise training intervention in men with peripheral arterial disease (PAD) and intermittent calf claudication.