Adherence and perceptions of a home sports video gaming program in persons with spinal cord injuries: A pilot study

OBJECTIVE

Sports video-gaming can facilitate increased activity levels in persons with limited exercise options. Understanding how persons with spinal cord injuries (SCI) participate in home-based video-gaming and its potential impact on maintaining or enhancing physical function remains largely unexplored. The purpose of this study was to evaluate adherence, perceptions, and potential physical effects of a home sports video-game program for persons with chronic SCI.

PARTICIPANTS

Fourteen individuals with chronic SCI (9 tetraplegia, 5 paraplegia).

DESIGN

This was a prospective study. Wii video-gaming systems that included four sports games were provided to participants for home use. Participants were instructed to play for 8 weeks 3-4 days/week. The video consoles recorded the time and number of sessions played.

OUTCOME MEASURES

At baseline and at the conclusion of the program, measurements were made of upper extremity strength, perceived exertion, active heart rate, pain, balance, and a functional upper extremity (UE) test. The total time and number of sessions were compared to the prescribed game play as a measure of adherence. Scores from a self-reported survey were used to gauge participants' satisfaction and perceptions of their gaming experience.

RESULTS

Overall mean gaming adherence was 85% during the first 4 weeks and 69% for the second 4 weeks. There were no significant changes in upper extremity strength, active heart rate, balance, pain, or functional UE test for either group. All of the participants rated video gaming as enjoyable and 85.7% perceived that it could be used as a form of exercise.

CONCLUSION

The Wii sports home video-gaming intervention elicited overall high adherence rates and was well received by study participants indicating that it may have value as an adjunctive tool for increasing physical activity for individuals with SCI.

Association of physical function and performance with peak VO2 in elderly patients with end stage kidney disease

BACKGROUND

Physical function is impaired in end stage renal disease (ESRD). Various instruments have been used to assess the functional capabilities and health status of patients with ESRD, but it is not known which has the best association with peak VO₂.

AIMS

To assess the association between functional measures in ESRD.

METHODS

Thirty nine elderly ESRD patients were evaluated with commonly used functional, health status, and quality of life measures, including maximal cardiopulmonary exercise testing (CPET), 6-min walk (6MWT), sit-to-stand test (STS), Veterans Specific Activity Questionnaire (VSAQ), upper and lower body strength, pulmonary function tests, and body composition determined by dual X-ray absorptiometry. The association between performance on these functional tools, clinical variables, and exercise test responses was assessed, and a non-exercise test multivariate model was developed to predict peak VO₂.

RESULTS

Peak VO₂ was modestly related to VSAQ score (r = 0.59, p < 0.01), indices of upper and lower body strength (r = 0.45, p < 0.01 for both), and FEV₁ (r = 0.51, p < 0.01). Functional and quality of life questionnaires were generally poorly related to one another and to peak VO₂. In a multivariate model, 6MWT performance, forced expiratory volume in 1 s (FEV₁), and VSAQ score were the best predictors of peak VO₂, yielding a multiple R = 0.82, accounting for 67% of the variance in peak VO₂.

CONCLUSION

Exercise capacity can be reasonably estimated using non-exercise test variables in patients with ESRD, including a symptom questionnaire (VSAQ), 6MWT and FEV₁.

CLINICAL TRIAL INFORMATION

ClinicalTrials.gov identifier: NCT01990495. Registered Nov 21, 2013.

Effect of a Home-Based Exercise Program on Indices of Physical Function and Quality of Life in Elderly Maintenance Hemodialysis Patients

BACKGROUND

Patients on maintenance hemodialysis (MHD) exhibit muscle wasting and impaired physical function which can be reversed with regular exercise, but accessibility to exercise programs for this unique population is lacking. We assessed the efficacy of a home-based exercise program on a broad range of indices of physical function, quality of life (QoL), and cognitive decline in patients with MHD.

DESIGN AND METHODS

Twenty-eight MHD patients, mean age 66 ± 7 years, were randomized to a 12-week home-based, case-managed aerobic and resistance exercise program or to usual care (13 exercise and 15 usual care). Comparisons were made for peak VO2, ventilatory inefficiency, 6-min walk test (6MWT), 1-min sit-to-stand (1STS), muscle strength, body composition, QoL, and cognitive measures.

RESULTS

Peak VO2 improved significantly in the exercise group (p = 0.01 between groups); exercise time improved by 41 and 36% at the ventilatory threshold and peak exercise, respectively (p < 0.01 between groups), but there were no differences in ventilatory efficiency. Trends for improvements in 6MWT and 1STS in the exercise group were observed, but no differences were observed in strength or body composition. Among measures of QoL, general health determined by the SF-36 improved in the exercise group, but there were no differences between groups in cognitive function.

CONCLUSIONS

MHD patients improved exercise capacity and some indices of QoL following a 12-week home-based exercise program. Home-based exercise is feasible for patients undergoing MHD and may help to obviate accessibility barriers to regular exercise.

Comprehensive Lifestyle Medicine Program Improves Fitness, Function, and Blood Pressure in Poststroke Veteran Cohort: A Pilot Study

Comprehensive lifestyle medicine programs have begun to show efficacy in patients with cerebrovascular disease. The Veterans Affairs (VA) health care system has a large poststroke population and VA rehabilitation departments have significant expertise and resources for promoting healthy lifestyles. A 12-week clinical lifestyle medicine program was therefore implemented for poststroke patients, along with an optional observational study evaluating cardiovascular fitness, function, body composition, vitals, and quality of life before and after the program. Seventeen of 18 clinical patients elected to participate in the study, and 3 later withdrew. The 14 participants improved VO2 max by 1.94 mL O2/min/kg ( P = .001, 95% CI 0.96-2.90). Significant improvements were seen in estimated metabolic equivalents, exercise duration, 6-minute walk test, 30-second sit to stand, grip strength, and balance. Among patients who were hypertensive at baseline, mean decrease in supine systolic blood pressure (SBP) was −9.70 mm Hg (n = 10, P = .005, 95% CI −15.7 to −3.7) and standing SBP was −11.09 mm Hg (n = 11, P = .009, 95% CI −18.7 to −3.48). There were no significant improvements in laboratory measures or body composition. Participant satisfaction was high. These findings corroborate recent literature suggesting that lifestyle programs improve stroke recovery and reduce recurrence risk.

Quantitative electrodiagnostic patterns of damage and recovery after spinal cord injury: a pilot study

Study design

Prospective observational pilot study.

Objectives

To compare quantitative electromyographic (EMG), imaging and strength data at two time points in individuals with cervical spinal cord injury (SCI).

Setting

SCI center, Veterans Affairs Health Care System, Palo Alto, California, USA.

Methods

Subjects without suspected peripheral nerve injury were recruited within 3 months of injury. Needle EMG examination was performed in myotomes above, at, and below the SCI level around 11- and 12-months post injury. EMG data were decomposed using custom software into constituent motor unit trains and each distinct motor unit was analyzed for firing rate and amplitude. Strength measurements were made with dynamometry and according to the International Standard of Neurologic Classification of SCI (ISNCSCI). Cervical magnetic resonance images (MRI) were evaluated by two neuroradiologists for gray and white matter damage around the SCI. Here, we compare the EMG, strength, and imaging findings of the one of the four participants who completed both 3- and 12-month EMG evaluations.

Results

There was an increase in force generation in all muscles tested at 1 year. Localized findings of very fast firing motor units helped localize spinal cord damage and revealed gray matter damage in spinal segments where MRI was normal. Meanwhile, improvement in strength over time corresponded with different electrophysiologic patterns.

Conclusions

Electromyographic decomposition at two time points provides valuable information about localization of spinal cord damage, integrity of motor neuron pools and may provide a unique understanding of neural recovery mechanisms.

Upper limb muscle activation during sports video gaming of persons with spinal cord injury

OBJECTIVE

Video gaming as a therapeutic tool has largely been studied within the stroke population with some benefits reported in upper limb motor performance, balance, coordination, and cardiovascular status. To date, muscle activation of upper limb muscles in persons with spinal cord injuries (SCI) has not been studied during video game play. In this paper, we provide descriptive and comparative data for muscle activation and strength during gaming for players with tetraplegia and paraplegia, as well as, compare these results with data from traditional arm exercises (ie, biceps curl and shoulder press) with light weights which are commonly prescribed for a home program.

PARTICIPANTS

Fourteen individuals with chronic SCI (9 tetraplegia, 5 paraplegia).

DESIGN

We measured upper limb muscle activation with surface electromyography (EMG) during Wii Sports video game play. Muscle activation was recorded from the playing arm during 4 selected games and normalized to a maximum voluntary contraction (MVC).

OUTCOME MEASURES

Heart rate and upper limb motion were recorded simultaneously with EMG. Wilcoxon signed rank tests were used to analyze differences in muscle activation between participants with paraplegia versus tetraplegia and compare gaming with traditional arm exercises with light weights. A Friedman 2-way analysis of variance identified key muscle groups active during game play.

RESULTS

Overall muscle activation across the games was not different between those with paraplegia and tetraplegia. Heart rate during video game play for tennis and boxing were on average 10 to 20 beats/minute above resting heart rate. The magnitude of EMG was relatively greater for traditional arm exercises with light weights compared with game play.

CONCLUSION

The selected Wii games were able to elicit upper extremity muscle activation and elevated heart rates for individuals with SCI that may be used to target therapeutic outcomes.

Bone changes in the lower limbs from participation in an FES rowing exercise program implemented within two years after traumatic spinal cord injury

Objective: To determine the effect of a functional electrical stimulation (FES) rowing program on bone mineral density (BMD) when implemented within two years after SCI.Design: Prospective.Setting: Health Care Facility.Participants: Convenience sample; four adults with recent (<2 years) traumatic, motor complete SCI (C7-T12 AIS A-B).Intervention: A 90-session FES rowing exercise program; participants attended 30-minute FES training sessions approximately three times each week for the duration of their participation.Outcome Measures: BMD in the distal femur and tibia were measured using peripheral Quantitative Computed Tomography (pQCT) at enrollment (T₀) and after 30 (T₁), 60 (T₂), and 90 (T₃) sessions. Bone stimulus was calculated for each rower at each time point using the average number of weekly loading cycles, peak foot reaction force, and bone mineral content from the previous time point. A regression analysis was used to determine the relationship between calculated bone stimulus and change in femoral trabecular BMD between time points.Results: Trabecular BMD in the femur and tibia decreased for all participants in T_0-1, but the rate of loss slowed or reversed between T_1-2, with little-to-no bone loss for most participants during T_2-3. The calculated bone stimulus was significantly correlated with change in femoral trabecular BMD (P = 0.016; R²= 0.458).Conclusion: Consistent participation in an FES rowing program provides sufficient forces and loading cycles to reduce or reverse expected bone loss at the distal femur and tibia, at least temporarily, in some individuals within two years after SCI.Trial Registration: NCT02008149.

Pixel-Based DXA-Derived Structural Properties Strongly Correlate with pQCT Measures at the One-Third Distal Femur Site

While bone mineral density has been traditionally used to quantify fracture risk for individuals with spinal cord injuries, recent studies are including engineering measurements such as section modulus and cross sectional moment of inertia. These are almost exclusively calculated by peripheral QCT scanners which, unlike DXA scanners, are rarely found in clinical settings. Using fifty-four fresh frozen femora, we developed and validated a pixel-by-pixel method to calculate engineering properties at the distal femur using a Hologic QDR-1000 W DXA scanner and compared them against similar parameters measured using a Stratec XCT-3000 peripheral QCT scanner. We found excellent agreement between standard DXA and pixel-by-pixel measured BMD (r ² = 0.996). Cross-sectional moment of inertia about the anteroposterior axis measured using DXA and pQCT correlated very strongly (r ² = 0.99). Cross-sectional moment of inertia about the anteroposterior axis measured using DXA also correlated strongly with pQCT measured bone strength index (r ² = 0.99). These correlations indicate that DXA scans can measure equivalent pQCT parameters, and some existing DXA scans can be reprocessed with pixel-by-pixel techniques. Ultimately, these engineering parameters may help better quantify fracture-risk in fracture-prone populations such as those with spinal cord injuries.

Randomized controlled trial of pharmacological replacement of melatonin for sleep disruption in individuals with tetraplegia

OBJECTIVE

To determine the effectiveness of a melatonin agonist for treating sleep disturbances in individuals with tetraplegia.

DESIGN

Placebo-controlled, double-blind, crossover, randomized control trial.

SETTING

At home.

PARTICIPANTS

Eight individuals with tetraplegia, having an absence of endogenous melatonin production and the presence of a sleep disorder. Interventions Three weeks of 8 mg of ramelteon (melatonin agonist) and 3 weeks of placebo (crossover, randomized order) with 2 weeks of baseline prior to and 2 weeks of washout between active conditions.

OUTCOME

Change in objective and subjective sleep.

MEASURES

Wrist actigraphy, post-sleep questionnaire, Stanford sleepiness scale, SF-36.

RESULTS

We observed no consistent changes in either subjective or objective measures of sleep, including subjective sleep latency (P = 0.55, Friedman test), number of awakenings (P = 0.17, Friedman test), subjective total sleep time (P = 0.45, Friedman test), subjective morning alertness (P = 0.35, Friedman test), objective wake after sleep onset (P = 0.70, Friedman test), or objective sleep efficiency (P = 0.78, Friedman test). There were significant increases in both objective total sleep time (P < 0.05, Friedman test), subjective time in bed (P < 0.05, Friedman test), and subjective sleep quality (P < 0.05, Friedman test), although these occurred in both arms. There were no significant changes in any of the nine SF-36 subscale scores (Friedman test, Ps >Bonferroni adjusted α of 0.005).

CONCLUSION

In this pilot study, we were unable to show effectiveness of pharmacological replacement of melatonin for the treatment of self-reported sleep problems in individuals with tetraplegia. Trial Registration ClinicalTrials.gov # NCT00507546.

Triceps Brachii in Incomplete Tetraplegia: EMG and Dynamometer Evaluation of Residual Motor Resources and Capacity for Strengthening

BACKGROUND

Candidates for activity-based therapy after spinal cord injury (SCI) are often selected on the basis of manual muscle test scores and the classification of the injury as complete or incomplete. However, these scores may not adequately predict which individuals have sufficient residual motor resources for the therapy to be beneficial.

OBJECTIVE

We performed a preliminary study to see whether dynamometry and quantitative electromyography (EMG) can provide a more detailed assessment of residual motor resources.

METHODS

We measured elbow extension strength using a hand-held dynamometer and recorded fine-wire EMG from the triceps brachii muscles of 4 individuals with C5, C6, or C7 level SCI and 2 able-bodied controls. We used EMG decomposition to measure motor unit action potential (MUAP) amplitudes and motor unit (MU) recruitment and firing-rate profiles during constant and ramp contractions.

RESULTS

All 4 subjects with cervical SCI (cSCI) had increased MUAP amplitudes indicative of denervation. Two of the subjects with cSCI had very weak elbow extension strength (<4 kg), dramatically reduced recruitment, and excessive firing rates (>40 pps), suggesting profound loss of motoneurons. The other 2 subjects with cSCI had stronger elbow extension (>6 kg), more normal recruitment, and more normal firing rates, suggesting a substantial remaining motoneuron population.

CONCLUSIONS

Dynamometry and quantitative EMG may provide information about the extent of gray matter loss in cSCI to help guide rehabilitation strategies.

Maintaining femoral bone density in adults: how many steps per day are enough?

The amount and intensity of walking to maintain a healthy skeleton is unknown. This study examined the relationship between habitual walking activity and femoral bone mineral density (BMD) in healthy individuals using a quantitative theory for bone maintenance. Our results suggest a gender, weight, and speed sensitivity of walking interventions.

INTRODUCTION

Walking has been extensively promoted for the prevention of osteoporosis. The amount and intensity of walking to maintain a healthy skeleton is unknown and evidence to support a specific target of steps per day is lacking. The goal of our study was to examine the relationship between habitual walking activity and femoral bone mineral density (BMD) in healthy individuals using a quantitative theory for bone maintenance.

METHODS

Habitual walking activity and total femur BMD were measured in 105 individuals (49-64 years). An index of cumulative loading (bone density index, BDI) was examined as a predictor of BMD. The BDI-BMD relationship was used to predict the steps per day to maintain healthy BMD values for a range of body weights (BW) and walking speeds.

RESULTS

For females but not for males, BDI was correlated with BMD (r (2) = 0.19, p < 0.001). The total required steps per day to maintain a T-score of -1.0 for a female with the average BW of the study cohort, walking at 1.00 m/s is 4,892 steps/day. Substantially more steps (18,568 steps/day) are required for a female with a BW 20% lighter than the average for our female cohort. For these lighter females, only at a walking speed greater than 1.32 m/s was 10,000 steps/day sufficient to maintain a T-score of -1.0.

CONCLUSIONS

Our results suggest a gender, weight, and speed sensitivity of walking interventions for osteoporosis. In persons of low BW, the necessary steps per day to maintain BMD can be substantially greater than the often-quoted 10,000 steps.

Validation of home telehealth for pressure ulcer assessment: a study in patients with spinal cord injury

The reliability and validity of assessments and diagnoses made via home telehealth was measured in 42 patients with spinal cord injury. Two telehealth modalities were investigated: telephone-only contact and videoconferencing. The results were compared with a reference (gold-standard) method, the in-person assessment and diagnosis of skin integrity and pressure ulcers. The agreement on the presence of a pressure ulcer was excellent for both telephone and videoconferencing approaches (92% for telephone, 97% for videoconferencing). The diagnoses of the stage of pressure ulcer (on an ordinal scale of 0-4) made via telephone and videoconferencing showed substantial to almost perfect agreement with the in-person diagnoses (Spearman's rho of 0.76 and 0.83, respectively). There was a tendency for the measurements of wound volume to be somewhat larger in the telephone and videoconferencing modalities compared to those made in-person. Bland-Altman plots showed that videoconferencing gave substantially narrower 95% limits of agreement. The findings of the study indicate that telephone contact can be a useful tool for identifying the presence of a pressure ulcer, but videoconferencing is required to obtain an evaluation reasonably close to that of a home visit.

Reproducibility of noninvasive cardiac output during arm exercise in spinal cord injury

The carbon dioxide (CO(2)) rebreathing method is a noninvasive technique to estimate cardiac output during exercise, but few data are available on the validity and reliability of this measure in individuals with spinal cord injury (SCI). Sixteen male subjects with SCI (mean age 45 +/- 9, seven paraplegic and nine tetraplegic) underwent three submaximal steady state arm ergometer exercise tests. We estimated cardiac output using the exponential CO(2) rebreathing technique at an individualized exercise intensity approximating 50% of peak oxygen uptake. Mean values for the cardiac output measurements were 13.0 +/- 2.4, 13.3 +/- 2.0, and 13.4 +/- 1.7 L/min; the difference among the trials was not significant (p = 0.54). The typical error was 1.80 +/- 0.85 L/min, the limits of agreement were 11.3 to 15.3 L/min, the coefficient of variation was 5.4% +/- 3.4%, and the intraclass correlation coefficient was 0.85 (95% confidence interval = 0.70-0.94). The test-to-test variation in estimated cardiac output during arm ergometry in individuals with SCI is similar to that observed in studies that used this technique in ambulatory persons. The 5% relative variation between tests suggests that the CO(2) rebreathing technique for estimating cardiac output can be performed in SCI individuals with acceptable reproducibility.

Key characteristics of walking correlate with bone density in individuals with chronic stroke

Several recent studies of ambulatory stroke survivors have shown decreased bone mineral density (BMD) in the lower limbs and an elevated risk of hip fracture. Because bone mass is linked to skeletal loading, weight-bearing activities of daily living such as walking are considered critically important for maintenance of femoral BMD in ambulatory individuals. Little is known about the relationships between walking characteristics, skeletal loading, and bone maintenance in individuals who have experienced a stroke. This study determined whether certain gait-related parameters correlate with proximal femoral BMD in ambulatory individuals with poststroke walking deficits. We analyzed data from 33 individuals with chronic stroke and found that a recently introduced metric, the Bone Density Index, which incorporates body weight, number of steps per day, and ground reaction force magnitude, predicted proximal femoral BMD better than other commonly measured demographic and gait-related parameters that we examined.

Homocysteine and hypertension in persons with spinal cord injury

STUDY DESIGN

Cross-sectional analysis of a convenience sample of locally recruited participants, including both patients and volunteers.

OBJECTIVES

To determine whether there is an association between plasma homocysteine and hypertension in persons with spinal cord injury (SCI).

SETTING

Spinal Cord Injury Service of the Veterans Affairs Palo Alto Medical Center (California, United States of America).

METHODS

The incidence of hypertension, dyslipidemia, insulin resistance, and the presence of metabolic syndrome were determined in 168 individuals with SCI (mean age 50.2 +/- 12.8 years). Fasting lipids, insulin, glucose, plasma homocysteine, and anthropometric data was gathered for each subject.

RESULTS

Blood pressure values (P < 0.001) and mean arterial pressure (P < 0.05) increased with higher plasma homocysteine levels. Homocysteine values were also significantly greater among individuals with hypertension compared with those who were normotensive or prehypertensive (P < 0.0001). There was an inverse relationship between plasma homocysteine levels and glomerular filtration rate and effective renal plasma flow (P < 0.05).

CONCLUSIONS

Plasma homocysteine levels are elevated in persons with SCI who have hypertension and inversely related to renal function, which suggests that renal dysfunction may be a link between homocysteine and hypertension in persons with SCI.

SPONSORSHIP

Funded by the VA Rehabilitation Research and Development Service, Merit Review Grant #B2549R.

C-reactive protein, metabolic syndrome, and insulin resistance in individuals with spinal cord injury

BACKGROUND/OBJECTIVE

High-sensitivity C-reactive protein (hsCRP) has been shown to be indicative of elevated risk of cardiovascular disease (CVD). We examined this blood marker in persons with spinal cord injury (SCI) in order to determine its potential for predicting elevated cardiac risk.

METHODS

In a cross-sectional analysis, we examined the relationship between hsCRP and insulin resistance and metabolic syndrome among 93 individuals with SCI (50.2 +/- 13 years). Fasting lipids, insulin, glucose, plasma hsCRP, and anthropometric data were gathered from each subject. Comparisons were made with population reference values.

RESULTS

Metabolic syndrome and insulin resistance were present in nearly one quarter of the SCI population (22.6%). Subjects with fasting insulin resistance had significantly higher mean hsCRP (4.29 +/- 3.25 mg/L) than those who were not insulin resistant (2.24 +/- 2.02) (P < 0.05). Moreover, hsCRP was significantly elevated in individuals who presented with high cardiovascular risk including severe dyslipidemia (> or = 4 abnormal lipid values) and Framingham Risk scores < or = 6 (P < 0.05 for both values). In addition, the homeostasis model assessment of insulin resistance was mildly correlated with hsCRP (r = 0.33).

CONCLUSIONS

In individuals with SCI who are insulin resistant and/or display components of the metabolic syndrome, hsCRP is elevated suggesting a clinically important association with cardiovascular risk in this population.

Heart rate as a predictor of energy expenditure in people with spinal cord injury

This study evaluated the accuracy of heart rate calibrated from a maximum exercise test for predicting energy expenditure during five activities of daily living (ADL) in participants with spinal cord injury (SCI). Thirteen individuals with SCI underwent maximum exercise testing, followed by portable heart rate and metabolic testing during five ADL. A regression equation was developed from heart rate and oxygen uptake responses during the maximum exercise test for each subject. Based on this individualized equation, heart rate measured during the ADL was used to estimate energy expenditure for each participant. Predicted energy expenditure from heart rate was compared with that measured by indirect calorimetry with the use of oxygen uptake. Heart rate derived from the individualized regression equations explained 55% of the variance in measured energy expenditure, compared with only 8.3% from heart rate alone. However, calibrated heart rate consistently overestimated the actual kilocalories used; on average, the estimated energy expenditure was roughly 25% higher than that measured by oxygen uptake. Heart rate can be used as a gross estimate of energy expenditure during higher-intensity ADL in people with SCI when individual calibration of heart rate from maximum exercise testing is used.

Foot Cooling Reduces Exercise-Induced Hyperthermia in Men with Spinal Cord Injury

The number of individuals with spinal cord injury (SCI) participating in sports at recreational and elite levels is on the rise. However, loss of autonomic nervous system function below the lesion can compromise thermoregulatory capacity and increase the risk of heat stress relative to able-bodied (AB) individuals.

PURPOSE

To test the hypotheses that exercise in a heated environment would increase tympanic temperature (TTY) more in individuals with SCI than AB individuals, and that foot cooling using a new device would attenuate the rise in TTY during exercise in both groups.

METHODS

Six subjects with SCI (lesions C5-T5) and six AB controls were tested in a heated environment (means +/- SEM, temperature = 31.8 +/- 0.2 degrees C, humidity = 26 +/- 1%) for 45 min at 66% +/- 5 of arm cranking VO2peak and 30 min of recovery on two separate occasions with foot cooling (FC) or no foot cooling (NC) in randomized order.

RESULTS

During exercise and recovery in both trials, SCI TTY was elevated above baseline (P < 0.001) but more so in the NC versus FC trial (1.6 +/- 0.2 degrees C vs 1.0 +/- 0.2 degrees C, respectively, P < 0.005). Within the AB group, TTY was elevated above baseline for both trials (P < 0.001) with peak increases of 0.5 +/- 0.2 degrees C and 0.3 +/- 0.2 degrees C for NC and FC, respectively. TTY, face, and back temperature were higher in both SCI trials compared with AB trials (P < 0.05). Heart rate during exercise and recovery was lower in the SCI FC versus SCI NC (P < 0.05).

CONCLUSION

These results suggest that extraction of heat through the foot may provide an effective way to manipulate tympanic temperature in individuals with SCI, especially during exercise in the heat.

The effects of colostomy on the quality of life in patients with spinal cord injury: a retrospective analysis

PURPOSE

The purpose of this study was to evaluate the effects of colostomy on the quality of life (QOL) in patients with spinal cord injury (SCI) by designing a questionnaire that used self-reported data and correlating these data with the clinical information obtained from patients' medical records.

MATERIALS AND METHODS

A comprehensive QOL questionnaire was designed to specifically address the following 5 domains: physical health, psychosocial adjustment, body image, self-efficacy, and recreation/leisure. This questionnaire was completed during a telephone or an in-person interview. The subjective data derived from the questionnaire were correlated with objective medical information obtained from a review of medical records.

RESULTS

The QOL improved significantly (t = 9.1 28, P < .0001) after colostomy. All 27 (100%) patients were "satisfied," and 16 (59%) of them were "very satisfied" with colostomy. Nineteen (70%) patients would have preferred to have the colostomy done earlier, and only 3 (11%) patients wished it reversed. Colostomy reduced the number of hospitalizations caused by chronic bowel dysfunction by 70.4%. After colostomy, the average amount of time spent on bowel care was reduced from 117.0 min/day to 12.8 min/day (t = 7.964, P < .0001). All patients stated that colostomy simplified bowel care routine and increased independence. Significant improvements were recorded in the areas of physical health, psychosocial adjustment, and self-efficacy. Stoma prolapse and wound dehiscence were the most common complications of stomal surgery. When compared with medical data, patients were able to reliably recall average time with bowel problems (r = .881, P < .0001) and stomal surgery complications (r = .810, P < .0001).

CONCLUSION

Colostomy is a safe and effective treatment for chronic bowel dysfunction in patients with spinal cord injury. It is well accepted by the patients and significantly improves QOL and bowel management procedures. Correlation analysis indicates that subjective patient-reported data are consistent with objective data obtained from the medical records.

Early repolarization in patients with spinal cord injury: prevalence and clinical significance

OBJECTIVES

The objective was to examine the prevalence of early repolarization in a spinal cord injury (SCI) clinic and the relationship of level of injury to this electrocardiogram (ECG) finding.

BACKGROUND

ST elevation on the resting ECG can be either a normal variant or a sign of acute ischemia, evolving myocardial infarction, or pericarditis. It is frequently seen as a normal variant (early repolarization) in healthy individuals, but has also been reported in individuals with SCI. While the etiology of benign ST elevation (early repolarization) has not been clearly defined, current opinion is that this finding is seen in individuals with high vagal tone.

METHODS

Retrospective analysis was made of 31 5 individuals with SCI at T5 or above (140 with complete injuries), and 1 98 with SCI at T6 or below, and who had ECGs in the computerized database at the Palo Alto VA Medical Center. A comparison cohort of 32,841 able-bodied male controls also was identified in the same ECG database. Patient demographics and computerized ST measurements were analyzed.

RESULTS

The prevalence of ST elevation was significantly higher in both the total high-level injury group (19%) and the complete high-injury group (24.5%) than in either the low-injury (6.5%) or control groups (13%), with P < 0.001 for comparisons between both high- and low-injury groups and high injury vs control. The magnitude of ST elevation was also higher in the high-injury groups vs the low-injury and control groups.

CONCLUSION

There is a higher prevalence of early repolarization in individuals with SCI at levels of injury that can disrupt central sympathetic command of the heart. It appears that either enhanced vagal tone or loss of sympathetic tone is responsible for ST elevation.

Progressive decrease in bone density over 10 years of androgen deprivation therapy in patients with prostate cancer

OBJECTIVES

Several reports suggest an increased incidence of osteoporosis and concomitant fractures in men receiving androgen deprivation therapy (ADT) for prostate cancer. We sought to estimate the longitudinal effects of ADT on loss of bone density in this cross-sectional study.

METHODS

Hip and spine bone mineral density (BMD) studies were performed by dual-energy x-ray absorptiometry on 36 patients with prostate cancer. The year 0 cohort (n = 8) consisted of patients who had not yet begun planned ADT. These men were compared to patients receiving ADT who underwent BMD evaluation at year 2 (n = 6), year 4 (n = 7), year 6 (n = 5), year 8 (n = 5), and year 10 (n = 5) of therapy. All BMD values for the patients with prostate cancer were compared to age-matched control subjects.

RESULTS

Hip BMD was significantly lower in patients on ADT (mean BMD 0.802 g/cm(2)) compared with those not on ADT (mean BMD 0.935 g/cm(2)). Patients at year 0 had hip and spine BMD similar to age-matched control subjects. There was a significant trend for decreased hip BMD with increasing years of ADT (r = 0.46, P = 0.00008). This relationship was more dramatic when hip BMD at each time point was compared to age-matched control subjects (r = 0.55, P = 0.5 x 10(-16)). This bone loss was evident even up to year 10. BMD loss was more dramatic in patients who had undergone surgical castration than those receiving medical ADT (P = 0.08). Patients on intermittent ADT had similar BMD loss as patients on continuous ADT at year 2 and year 4 but demonstrated less bone loss at year 6 (P = 0.07) despite equivalently low testosterone levels.

CONCLUSIONS

There is diminished BMD with increasing duration of ADT. Continuous ADT and surgical castration may be more deleterious than medical therapy, particularly when the medical therapy is given in an intermittent fashion.

Bone mineral and geometric changes through the femur with immobilization due to spinal cord injury

This cross-sectional study describes bone mineral and geometric properties of the midshaft and distal femur in a control population and examines effects of immobilization due to spinal cord injury (SCI) at these skeletal sites. The subject populations were comprised of 118 ambulatory adults (59 men and 59 women) and 246 individuals with SCI (239 men and 7 women); 30 of these were considered to have acute injury (SCI duration <1 year). Bone mineral density (BMD) was assessed at the femoral neck, and midshaft and distal femur by dual energy absorptiometry. Geometric properties, specifically cortical area, polar moment of inertia, and polar section modulus, were estimated at the midshaft from cortical dimensions obtained by concurrent radiography. Reduction in BMD was noted in all femoral regions (27%, 25%, and 43% for femoral neck, midshaft, and distal femur, respectively) compared with controls. In contrast, although endosteal diameter was enlarged, geometric properties were not significantly reduced in the midshaft attributable to the age-related increase in periosteal diameter. These results suggest that simultaneous assessment of bone mineral and geometric properties may improve clinically relevant evaluation of skeletal status.

Mechanobiology of femoral neck structure during adolescence

Understanding femoral neck structure may be critical to preventing fractures at this site. We examined the correlates of changes in the femoral neck during adolescence. Dual energy x-ray absorptiometry measurements of proximal femora were made in 101 Caucasian youths (ages 9 to 26 years). Relationships were examined between developmental parameters (age, pubertal stage, height, body mass, lean mass, and fat mass) and femoral structure (bone mineral content, bone mineral density, neck width, cross-sectional area, and cross-sectional strength). Lean body mass was the best predictor of femoral neck structure, explaining 53-87 percent of the variance, and was independent of gender. Body mass only explained 51-79 percent of the variance. Previously we found body mass to be the strongest predictor of femoral mid-diaphyseal cross-sectional properties. These findings suggest that trabecular bone of the femoral neck may be more responsive to its mechanical environment than the cortical diaphysis. In addition, lean body mass may be a more reliable predictor of muscle loading than body mass.

DXA-derived section modulus and bone mineral content predict long-bone torsional strength

Previous studies have used dual energy x-ray absorptiometry (DXA) scans to calculate the section modulus (Z) of adolescent and adult human femurs. The DXA-derived values of Z were assumed to be proportional to bone strength in bending and torsion. In this study we used dog (n 5), pig (n 4), and human (n 13) femurs covering a linear bone mineral content (BMCL) range of 0.91-6.1 g/cm. Using DXA scans, ex vivo torsional strength tests, and torsional finite element models, we assessed the validity of using the DXA-derived Z value as an indicator of strength. The correlation between BMCL and strength was r2 = 0.87 and the correlation between Z and strength was r2 = 0.86. Based on finite element results, the dog and pig section moduli were adjusted to be comparable to the human data based on cross-sectional shape and bone tissue shear strength differences. With these adjustments, the correlation between adjusted section modulus and measured strength did not improve (r2 = 0.87). These data indicate that DXA-derived section modulus can be used to predict strength over a wide range of bone sizes. However, a clear advantage of using DXA-derived section modulus rather than BMCL could not be found.

Effect of spinal cord injury on the heart and cardiovascular fitness

The use of various FES protocols to encourage increases in physical activity and to augment physical fitness and reduce heart disease risk is a relatively new, but growing field of investigation. The evidence so far supports its use in improving potential health benefits for patients with SCI. Such benefits may include more efficient and safer cardiac function; greater stimulus for metabolic, cardiovascular, and pulmonary training adaptations; and greater stimulus for skeletal muscle training adaptations. In addition, the availability of relatively inexpensive commercial FES units to elicit muscular contractions, the ease of use of gel-less, reusable electrodes, and the increasing popularity of home and commercial upper body exercise equipment mean that such benefits are likely to be more accessible to the SCI population through increased convenience and decreased cost. The US Department of Health and Human Services has identified those with SCI as a "special population" whose health problems are accentuated, and so need to be specifically addressed. FES presents "a clear opportunity.... For health promotion and disease prevention efforts to improve the health prospects and functional independence of people with disabilities." As a corollary to this, the Centers for Disease Control and Prevention have recommended the development of techniques to prevent or ameliorate secondary disabilities in persons with a SCI. Patients with SCI have an increased susceptibility to cardiac morbidity and mortality in the acute and early stages of their injury. Most of these patients make an excellent adaptation except when confronted with infection or hypoxia. SCI by itself does not promote atherosclerosis; however, in association with multiple secondary conditions related to SCI, along with advancing age, patients with SCI are predisposed to relatively greater risk of heart disease. The epidemiologic significance of this is reflected in demographic studies that indicate an increasing number of SCI patients becoming aged. Currently 71,000 (40%) of the total 179,000 patients with SCI living in the United States are older than 40 years, and 45,000 have injuries sustained more than 20 years earlier. In addition, new injuries in the older population are increasing (currently 11% of all injuries), and some of these new patients with SCI already have pre-existing cardiac disease. Studies have demonstrated that improved lifestyle, physical activity, lipid management, and dietary restrictions can affect major risk factors for coronary artery disease. Therefore an aggressive cardiac prevention program is appropriate for patients with SCI as part of their rehabilitation. At a given submaximal workload, arm exercise is performed at a greater physiologic cost than is leg exercise. At maximal effort, however, physiologic responses are generally greater in leg exercise than arm exercise. Arm exercise is less efficient and less effective than lower body exercise in developing and maintaining both central and peripheral aspects of cardiovascular fitness. The situation is further compounded in SCI because of poor venous return as a result of lower-limb blood pooling, as a result of lack of sympathetic tone, and a diminished or absent venous "muscle pump" in the legs. This latter mechanism perhaps contributes the greatest diminution in the potential for aerobic performance in the SCI population. Obtaining a cardiopulmonary training effect in individuals with SCI is quite possible. Current studies indicate decreases in submaximal HR, respiratory quotient, minute ventilation, and oxygen uptake, with increases in maximal power output, oxygen uptake, minute ventilation, and lactic acid. Individuals with SCI have been shown to benefit from lower limb functional electrical stimulation (FES)-induced exercise. Studies have consistently reported increases in lower limb strength and cycle endurance performance with these protocols, as well as improvements in metabolic and

Body mass is the primary determinant of midfemoral bone acquisition during adolescent growth

To study the determinants of bone mass and structure during adolescence, we analyzed the femoral mid-diaphysis of 375 healthy adolescents and young adults, ages 9-26 years, from four ethnic cohorts (African-American, Asian-American, Caucasian, and Hispanic). Whole-body dual-energy X-ray absorptiometry (DXA) scans were used to determine diaphyseal length and mid-diaphyseal diameter of the left femur, as well as linear bone mineral content (BMCL) of a region at the mid-diaphysis. Cross-sectional geometric properties were estimated and used to calculate two structural strength indicators: the section modulus and the whole bone strength index. When the relationships between the bone measurements and age, pubertal group, height, or body mass were evaluated, all cross-sectional femoral measures correlated most strongly with body mass. Multiple regressions accounting for gender and ethnicity provided little additional predictive value over the simple regressions with body mass alone. Furthermore, accounting for all developmental parameters (age, pubertal group, body mass, lean body mass, calcium intake, physical activity level) as well as ethnicity and gender in a single saturated model also did not generally significantly improve the predictive results achieved using only body mass. Our results indicate that increases in midfemoral bone mass and cross-sectional properties during adolescence are primarily related to increases in mechanical loading as reflected by body mass.

Measurement of bone mineral density by dual-energy x-ray absorptiometry in patients with the Wisconsin hip, an uncemented femoral stem

Although qualitative evidence of femoral bone remodeling, secondary to total hip arthroplasty (THA), is apparent on radiographs, quantification of change in bone mass from radiographs is limited. Dual-energy x-ray absorptiometry overcomes many of the limitations and yields accurate and precise bone mineral density (BMD) data. In this study, regional changes in femoral BMD were examined in 89 THA patients with a 2-year follow-up period. Thirty-two patients were evaluated initially before surgery and followed through the first 2 postoperative years. A second group was comprised of 57 patients whose surgery had been performed 1 to 6 years prior to entry into the study; they were also followed for 2 years hence. Thus, both immediate and later bone responses were evaluated prospectively. Maximal bone remodeling was seen in the first 6 months after THA and with a near plateau by the end of the first year. A slow yearly decline in BMD appeared to occur as long as 8 years after THA, thus demonstrating the long-term effects of the introduction of a femoral stem. Variance in preoperative BMD was explained by disease only; no other factors (age, weight, sex) showed significant associations, and body weight was the only variable that affected rate of remodeling after THA (not age, weight, sex, prosthesis size, nor disease). All patients were healthy, relatively young individuals who were good candidates for uncemented implantation, and none showed evidence of clinical complications or surgical failure. It is therefore suggested that the patterns and results reported here be viewed as normative data, that is, the typical skeletal adaptation to THA. In future application, observation of disparate BMD results as compared with these "normal" data may be predictive of abnormal response to surgery and potential for later problems.

Determinants of femoral geometry and structure during adolescent growth

Our goal was to understand developmental determinants of femoral structure during growth and sexual maturation by relating femoral measurements to gender and developmental factors (age, pubertal stage, height, and body mass). The bone mineral content of the femur was measured by dual energy x-ray absorptiometry in 101 healthy Caucasian adolescents and young adults, 9-26 years of age. After some simplifying assumptions had been made, cross-sectional geometric properties of the femoral midshaft were estimated. Two geometry-based structural indicators, the section modulus and whole bone strength index, were calculated to assess the structural characteristics of the femur. Femoral strength, as described by these structural indicators, increased dramatically from childhood through young adulthood. Regressions were performed between these femoral measurements and the developmental factors. Our data show that of age, pubertal stage, body mass, and height, body mass is the strongest predictor of femoral cross-sectional properties, and the correlation of body mass with femoral cross-sectional structure is independent of gender. A model including all four developmental factors and gender did not substantially increase the accuracy of predictions compared with the model with body mass alone. In light of previous research, we hypothesize that body mass is an indicator of in vivo loading and that this in vivo loading influences the cross-sectional growth of the long bones.

Noninvasive determination of bone mechanical properties using vibration response: a refined model and validation in vivo

Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical response tissue analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a direct validation has been lacking. A theoretical analysis of wave propagation through the compressed tissue revealed a strong mass effect dependent on the relative accelerations of the probe and bone. The previous mathematical model of the bone and overlying tissue system was reconfigured to incorporate the theoretical finding. This newer model (six-parameter) was used to interpret results using MRTA to determine bone cross-sectional bending stiffness, EIMRTA. The relationship between EIMRTA and theoretical EI values for padded aluminum rods was R2 = 0.999. A biological validation followed using monkey tibias. Each bone was tested in vivo with the MRTA instrument. Postmortem, the same tibias were excised and tested to failure in three-point bending to determine EI3-PT and maximum load. Diaphyseal bone mineral density (BMD) measurements were also made. The relationship between EI3-PT and in vivo EIMRTA using the six-parameter model is strong (R2 = 0.947) and better than that using the older model (R2 = 0.645). EIMRTA and BMD are also highly correlated (R2 = 0.853). MRTA measurements in vivo and BMD ex vivo are both good predictors of scaled maximum strength (R2 = 0.915 and R2 = 0.894, respectively). This is the first biological validation of a non-invasive mechanical measurement of bone by comparison to actual values. The MRTA technique has potential clinical value for assessing long-bone mechanical properties.

Determination of bone mineral density by dual x-ray absorptiometry in patients with uncemented total hip arthroplasty

Bone remodeling is an expected sequela with total hip arthroplasty (THA). Although there are several methods of estimating bone response in THA patients from radiographs, there are no accurate and generally accepted methods for quantitative determinations in vivo. In this study, we describe an application of dual x-ray absorptiometry (DXA) for measuring bone mineral content and bone mineral density in the proximal femur following THA. DXA is a noninvasive technique with minimal radiation exposure (< 5 mrem). Various aspects of measurement error (accuracy and reliability) of this application of DXA were determined in a series of studies reported here. Accuracy error (how similar are the measured and actual values) was < 1% determined in bone phantoms of four densities. Precision error (how reproducible are the measurements) was also < 1% at all four densities in the phantoms and was only slightly elevated (0.9-1.5%) in repeated measurements of implanted cadaver femora. Precision error in vivo, determined both from multiple replicates on five patients and from duplicate scans on 30 patients, was further elevated but remained < 5%. Contributions to precision error, rotation of the leg, and interoperator variability were assessed; none was found to elevate precision error appreciably. We suggest that DXA is a feasible method for quantifying bone response following THA, and will allow discrimination of small changes (> 5%) not previously measurable.

Mechanical effects of sodium fluoride on bovine cortical bone

Seventeen 5 to 6-month-old Holstein heifer calves were divided into three groups and fed either a control ration alone or a control ration with sufficient sodium fluoride added to furnish an additional 30 or 50 p.p.m. fluoride based on total dry matter intake. After 6 years of the feedings, mean (SEM) fluoride concentrations in the metacarpals were found to be 594.6 (66.2), 2663.8 (319.2), and 4500.0 (417.8) p.p.m. Bone mineral density and mechanical evaluations were also conducted on the harvested metacarpals after the 6-year period. Using dual energy X-ray absorptiometry, mean (SEM) bone mineral densities of 3.030 (0.26), 2.801 (0.34), and 2.456 (0.19) g cm(-2) for the control group, the group receiving 30 p.p.m. fluoride, and the group receiving 50 p.p.m. respectively were found. For the mechanical testing, specimens were cut and tested in compression parallel to the long axis of the metacarpals. Mean (SEM) ultimate stress of 204.53 (3.63), 208.83 (5.25), and 205.93 (5.12) MPa and mean (SEM) Young's elastic moduli of 20.82 (1.52), 22.68 (2.38), and 21.55 (1.60) GPa for the control, the 30 p.p.m., and the 50 p.p.m. fluoride groups respectively were determined. No significant differences were found between control and treatment groups for either mechanical properties or bone mineral density.

Dual photon absorptiometry of the proximal tibia

Bone mineral content (BMC) and bone mineral density (BMD) of the proximal tibia were determined by dual photon absorptiometry on 44 women, aged 23-87 years. The area of the tibia measured was a 2.01 cm region immediately distal to the medial and lateral tuberosities. Values of BMC ranged between 5.09 and 14.57 g and BMD between 0.380 and 1.180 g/cm2. Both tibial BMC and BMD declined with age and tibial BMD was significantly correlated with lumbar spine (r = 0.70), femoral neck (r = 0.73), and femoral trochanter (r = 0.74). However, the large standard errors of estimate (SEE) (0.08-0.14 g/cm2) do not allow for reliable prediction in an individual of other skeletal sites by the tibia. Repeated measurements demonstrated that dual photon absorptiometry of the proximal tibia is a reliable measurement and may be a useful tool in the monitoring of therapeutic or intervention modalities in those individuals with skeletal diseases in whom measurement of the lumbar spine or proximal femur may not be possible.