Biomedical subjects

Patrick L Jacobs

Publications and source records attributed to Patrick L Jacobs.

15 recordsLinked to original sources

PubMed2005

Relation between muscular strength and cardiorespiratory fitness in people with thoracic-level paraplegia.

OBJECTIVES: To determine the relation between muscular strength, aerobic power (V O2 peak), submaximal blood lactate accumulation, and endurance performance in people with thoracic-level paraplegia. DESIGN: Participants performed tests of isokinetic strength, a graded exercise test, and 2 endurance performance tests. A Latin square counterbalanced design was used to determine the order of testing. SETTING: Research laboratory in a university setting. PARTICIPANTS: Ten adult male volunteers with thoracic-level paraplegia. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The relations between strength, V O2 peak, submaximal blood lactate accumulation, and endurance were determined by correlation analysis. RESULTS: Shoulder flexion strength correlated with V O2 peak and power output at V O2 peak. Shoulder strength accounted for 68.4% of the variation in performance time. Greater isokinetic elbow flexion and extension strength was associated with higher V O2 and power output at a blood lactate concentration of 4 mmol/L (flexion) and with a greater power output at V O2 peak (extension). CONCLUSIONS: These findings suggest that in this population, greater muscular strength is associated with greater aerobic power and endurance. Greater muscular strength could exert a positive influence on exercise performance by enabling higher levels of cardiorespiratory stress as the result of reduced or delayed local muscle fatigue.

Adult↗

PubMed2005

Reliability of upper extremity anaerobic power assessment in persons with tetraplegia.

BACKGROUND/OBJECTIVE: Reliable assessment of upper extremity anaerobic power in persons with cervical spinal cord injury (SCI) may indicate the ability to successfully and safely perform many daily activities. PURPOSE: To examine test-retest reliability of upper extremity Wingate anaerobic testing (WAnT) in persons with motor/sensory complete tetraplegia. METHODS: Forty-five persons with cervical-level SCI (15 individuals each at C5, C6, and C7 levels of injury) performed 2-arm WAnT bouts, with 2 to 4 days between bouts. Subjects performed the WAnT seated in their wheelchairs using a tabletop-mounted Monarch 834E ergometer. Resistance loads were applied relative to injury level, with 1%, 2%, and 3% of body mass applied to subjects with C5, C6, and C7 level injuries, respectively. All subjects were directed to crank the ergometer at maximal velocity for a 30-second period. Values of peak power (Ppeak) and mean power (Pmean) were determined using an SMI OptoSensor 2000 system. Ppeak and Pmean were compared between trials and between groups using 2-way analyses of variance for repeated measures. Coefficients of determination (r2) were calculated between trials. RESULTS: There were no significant differences in Ppeak or Pmean detected between the 2 trials of WAnT in the C5, C6, or C7 groups. Regression analyses revealed statistically significant associations between bouts for Pmean and Ppeak in each of the 3 groups (P < 0.05). CONCLUSIONS: Upper extremity WAnT is reliable for upper extremity anaerobic power assessment in persons with cervical SCI at or below the C5 level.

Adult↗

PubMed2004

Metabolic and cardiac responses to robotic-assisted locomotion in motor-complete tetraplegia: a case report.

BACKGROUND/OBJECTIVE: To examine acute metabolic responses to treadmill locomotion in a participant with motor-complete tetraplegia. METHODS: The participant--a woman with a chronic ASIA B C3-C4 spinal cord injury--walked on a treadmill with 40% body weight support (BWS) and robotic assistance. Oxygen consumption (VO2), minute ventilation (VE), and heart rate (HR) were measured during seated resting, supported standing, and 40 minutes of walking with stepping assistance from a Lokomat-driven gait orthosis. RESULTS: A resting VO2 equal to 50 milliliters per minute was predictably low, and did not change after the participant assumed an upright posture. Both VO2 and VE increased immediately upon onset of locomotion, suggesting a neurogenic rather than a humoral regulatory response to movement. VO2 averaged 2.4 metabolic units (METS) during locomotion at an average expenditure of 2.98 kilocalories per minute. HR was unaltered by standing, but during locomotion averaged 1 7 beats higher than during resting. Increases in VE but not VO2 upon standing, and decreases in VO2 but not VE immediately after walking, rule out changes in VE alone as the source for increased VO2 during walking. CONCLUSION: The data collected on this single participant show that treadmill locomotion with BWS and robotic assistance elicits a metabolic response to treadmill gaiting characterized by increased VO2, VE, HR, and caloric expenditure.

Adult↗

PubMed2004

Combined hyperlipidemia in a single subject with tetraplegia: ineffective risk reduction after atorvastatin monotherapy.

BACKGROUND/OBJECTIVE: Effects of atorvastatin (Lipitor) drug monotherapy (10 mg daily) on fasting blood lipid profiles and cardiovascular disease (CVD) risks were examined for a single subject with C5-C6 tetraplegia. Routine fasting lipid profiles were analyzed by standard biochemistry techniques for total cholesterol (TC), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C). Lipid profiles were analyzed on 3 occasions before drug therapy was initiated and 3 months after therapy commenced. The TC:HDL and LDL:HDL ratios were computed for all sampling times and used to assess pretreatment and post-treatment CVD risk. RESULTS: Fasting TC, TG, and LDL-C were all significantly reduced by therapy. The pretreatment HDL-C of 35 mg/dL was lowered to 21 mg/dL. As a result, the TC:HDL risk ratio was only marginally reduced from 6.6 to 6.4, whereas the LDL:HDL risk ratio remained unchanged by treatment. CONCLUSIONS: In this man with tetraplegia, atorvastatin drug monotherapy rapidly lowered TC, TG, LDL-C, and HDL-C. However, the TC:HDL ratio, considered the best predictor of CVD risk, was unchanged.

Aged↗

PubMed2004

Exercise recommendations for individuals with spinal cord injury.

Persons with spinal cord injury (SCI) exhibit deficits in volitional motor control and sensation that limit not only the performance of daily tasks but also the overall activity level of these persons. This population has been characterised as extremely sedentary with an increased incidence of secondary complications including diabetes mellitus, hypertension and atherogenic lipid profiles. As the daily lifestyle of the average person with SCI is without adequate stress for conditioning purposes, structured exercise activities must be added to the regular schedule if the individual is to reduce the likelihood of secondary complications and/or to enhance their physical capacity. The acute exercise responses and the capacity for exercise conditioning are directly related to the level and completeness of the spinal lesion. Appropriate exercise testing and training of persons with SCI should be based on the individual's exercise capacity as determined by accurate assessment of the spinal lesion. The standard means of classification of SCI is by application of the International Standards for Classification of Spinal Cord Injury, written by the Neurological Standards Committee of the American Spinal Injury Association. Individuals with complete spinal injuries at or above the fourth thoracic level generally exhibit dramatically diminished cardiac acceleration with maximal heart rates less than 130 beats/min. The work capacity of these persons will be limited by reductions in cardiac output and circulation to the exercising musculature. Persons with complete spinal lesions below the T(10) level will generally display injuries to the lower motor neurons within the lower extremities and, therefore, will not retain the capacity for neuromuscular activation by means of electrical stimulation. Persons with paraplegia also exhibit reduced exercise capacity and increased heart rate responses (compared with the non-disabled), which have been associated with circulatory limitations within the paralysed tissues. The recommendations for endurance and strength training in persons with SCI do not vary dramatically from the advice offered to the general population. Systems of functional electrical stimulation activate muscular contractions within the paralysed muscles of some persons with SCI. Coordinated patterns of stimulation allows purposeful exercise movements including recumbent cycling, rowing and upright ambulation. Exercise activity in persons with SCI is not without risks, with increased risks related to systemic dysfunction following the spinal injury. These individuals may exhibit an autonomic dysreflexia, significantly reduced bone density below the spinal lesion, joint contractures and/or thermal dysregulation. Persons with SCI can benefit greatly by participation in exercise activities, but those benefits can be enhanced and the relative risks may be reduced with accurate classification of the spinal injury.

Electric Stimulation Therapy↗

PubMed2003

Fatigue compensation during FES using surface EMG.

Muscle fatigue limits the effectiveness of FES when applied to regain functional movements in spinal cord injured (SCI) individuals. The stimulation intensity must be manually increased to provide more force output to compensate for the decreasing muscle force due to fatigue. An artificial neural network (ANN) system was designed to compensate for muscle fatigue during functional electrical stimulation (FES) by maintaining a constant joint angle. Surface electromyography signals (EMG) from electrically stimulated muscles were used to determine when to increase the stimulation intensity when the muscle's output started to drop. In two separate experiments on able-bodied subjects seated in hard back chairs, electrical stimulation was continuously applied to fatigue either the biceps (during elbow flexion) or the quadriceps muscle (during leg extension) while recording the surface EMG. An ANN system was created using processed surface EMG as the input, and a discrete fatigue compensation control signal, indicating when to increase the stimulation current, as the output. In order to provide training examples and test the systems' performance, the stimulation current amplitude was manually increased to maintain constant joint angles. Manual stimulation amplitude increases were required upon observing a significant decrease in the joint angle. The goal of the ANN system was to generate fatigue compensation control signals in an attempt to maintain a constant joint angle. On average, the systems could correctly predict 78.5% of the instances at which a stimulation increase was required to maintain the joint angle. The performance of these ANN systems demonstrates the feasibility of using surface EMG feedback in an FES control system.

Adult↗

PubMed2003

Reliability of arm Wingate Anaerobic Testing in persons with complete paraplegia.

BACKGROUND: Accurate, reliable assessment of upper extremity muscular power in persons with paraplegia caused by spinal cord injury (SCI) would provide an objective indication of their ability to generate the forces necessary for the performance of daily activities. Wingate Anaerobic Testing (WAnT) consists of a 30-second sprint test on a cycle ergometer and has been used widely in both athletic and research settings. PURPOSE: To examine test-retest reliability of arm WAnT performance in persons with complete SCI and paraplegia. METHODS: Forty-three participants with thoracic-level paraplegia (T2 through T12) performed 2 trials of arm WAnT with 2 to 7 days between each trial. Testing was performed using a Monarch 834E ergometer with participants seated in their wheelchairs. Participants were directed to crank at maximal pace for 30 seconds against a resistance load equivalent to 3.5% of their body mass. The SMI OptoSensor 2000 system was used to determine values of peak power (P(peak)), mean power (P(mean)), minimum power, and rate of fatigue, which were compared between trials using 1-way analysis of variance for repeated measures. Coefficients of determination (r2) were calculated between trials for P(peak) and P(mean). RESULTS: No significant difference was found between trials for any of the power output variables. Regression analysis indicated that P(peak) and P(mean) were closely associated between the 2 trials (r2 = 0.92 and 0.94, respectively). CONCLUSION: Arm WAnT is a reliable measurement tool for the assessment of upper extremity muscular power in persons with complete paraplegia.

Activities of Daily Living↗

PubMed2003

Physiologic responses to electrically assisted and frame-supported standing in persons with paraplegia.

BACKGROUND: Systems of functional electrical stimulation (FES) have been demonstrated to enable some persons with paraplegia to stand and ambulate limited distances. However, the energy costs and acute physiologic responses associated with FES standing activities have not been well investigated. OBJECTIVE: To compare the physiologic responses of persons with paraplegia to active FES-assisted standing (AS) and frame-supported passive standing (PS). METHODS: Fifteen persons with paraplegia (T6-T11) previously habituated to FES ambulation, completed physiologic testing of PS and AS. The AS assessments were performed using a commercial FES system (Parastep-1; Altimed, Fresno, Calif); the PS tests used a commercial standing frame (Easy Stand 5000; Altimed, Fresno, Calif). Participants also performed a peak arm-cranking exercise (ACE) test using a progressive graded protocol in 3-minute stages and 10-watt power output increments to exhaustion. During all assessments, metabolic activity and heart rate (HR) were measured via open-circuit spirometry and 12-lead electrocardiography, respectively. Absolute physiologic responses to PS and AS were averaged over 1-minute periods at 5-minute intervals (5, 10, 15, 20, 25, and 30 minutes) and adjusted relative to peak values displayed during ACE to determine percentage of peak (%pk) values. Absolute and relative responses were compared between test conditions (AS and PS) and across time using two-way analysis of variance. RESULTS: The AS produced significantly greater values of VO2 (43%pk) than did PS (20%pk). The mean HR responses to PS (100-102 beats per minute [bpm] throughout) were significantly lower than during AS, which ranged from 108 bpm at 5 minutes to 132 bpm at test termination. CONCLUSION: Standing with FES requires significantly more energy than does AS and may provide a cardiorespiratory stress sufficient to meet minimal requirements for exercise conditioning.

Adult↗

PubMed2002

Oral creatine supplementation enhances upper extremity work capacity in persons with cervical-level spinal cord injury.

OBJECTIVE: To examine the effects of short-term creatine monohydrate supplementation on the upper extremity work capacity of persons with cervical-level spinal cord injury (SCI). DESIGN: Randomized, double-blind, placebo-controlled, crossover design study. Consists of 2 treatment phases lasting for 7 days, separated by a 21-day washout period. SETTING: University research laboratory trial. PARTICIPANTS: Sixteen men with complete cervical-level SCI (C5-7). INTERVENTION: Subjects were randomly assigned to 1 of 2 groups and received either 20g/d of creatine monohydrate supplement powder or placebo maltodextrin powder for the first treatment phase; the treatment was reversed in the second phase. Incremental peak arm ergometry tests, using 2-minute work stages and 1-minute recovery periods, were performed immediately before and after each treatment phase (total of 4 assessments). The initial stage was performed unloaded, with power output progressively increased 10 watts/stage until subjects had achieved volitional exhaustion. MAIN OUTCOME MEASURES: Peak power output, time to fatigue, heart rate, and metabolic measurements, including oxygen uptake (VO2), minute ventilation, tidal volume (VT), and respiration frequency. RESULTS: Significantly greater values of VO2, VCO2, and VT at peak effort after creatine supplementation (P <.001). CONCLUSIONS: Creatine supplementation enhances the exercise capacity in persons with complete cervical-level SCI and may promote greater exercise training benefits.

Administration, Oral↗

PubMed2002

A comparison of 2 circuit exercise training techniques for eliciting matched metabolic responses in persons with paraplegia.

OBJECTIVE: To test whether acute metabolic (VO(2)), chronotropic (heart rate), and perceptual (rating of perceived exertion; RPE) responses to exercise by persons with paraplegia differ when the exercise is on a multistation isoinertial exercise system (MultiGym) or on a customized system of Thera-Band resistance bands (ElasticGym). DESIGN: Within-subjects comparison of 2 treatments. SETTING: Academic medical center. PARTICIPANTS: Sixteen men and 1 woman with complete paraplegia (T4-L1), as defined by the American Spinal Injury Association. INTERVENTIONS: A circuit resistance training (CRT) program for persons with paraplegia was adapted to both a MultiGym and a customized ElasticGym. Exercises used for training and testing used 6 resistance maneuvers at 50% of the 1-repetition maximum (1-RM), with interposed rapid arm spinning. Subjects were habituated to both conditions for 2 weeks before testing on randomized nonconsecutive days. MAIN OUTCOME MEASURES: VO(2) (L/min) was measured by portable spirometry, heart rate (beats/min) by a chest strap monitor, and RPE by the Borg Scale of Perceived Exertion (6-20). RESULTS: No significant effects of test condition on average VO(2) or heart rate were observed, with differences between conditions reflecting only .08L/min and 6.4 beats/min, respectively. Average RPE was significantly higher in testing under the ElasticGym condition (P < .05). CONCLUSIONS: CRT on a customized ElasticGym system elicited acute metabolic and chronotropic responses that did not differ from responses to exercise on a MultiGym, though RPE was greater with the ElasticGym.

Adult↗

PubMed2002

Hypokinetic circulation in persons with paraplegia.

INTRODUCTION: It is well established that hemodynamic dysfunction, resulting in diminished upper-extremity work capacity, occurs in persons with spinal cord injury (SCI) as compared with those who are nondisabled (ND). Although it has been shown that persons with paraplegia display higher values of heart rate (HR) with lower values of stroke volume (SV) during exercise, it is not resolved whether there is adequate compensation to produce similar values of cardiac output (.Q) as in ND. PURPOSE: This study examined central cardiovascular responses (HR, SV, and .Q) of 20 subjects with complete thoracic level SCI (T(4)-T(11)) and 20 sedentary ND subjects during matched levels of arm-crank (AC) exercise. METHODS: All subjects performed an incremental peak AC test to volitional exhaustion with continuous metabolic analysis and HR measurement via open circuit spirometry and 12-lead electrocardiography, respectively. Stroke volume was assessed using transthoracic impedance. RESULTS: Heart rate was higher for SCI (P< 0.05) with significantly lower values for SV and .Q at rest (approximately 25%). Peak responses were significantly higher for ND in all factors except HR. Although subpeak HRs at matched absolute workloads were significantly higher for SCI (12-20 beats.min (-1) ), SV and .Q were significantly lower (P< 0.05). CONCLUSIONS: The results of this study indicate that .Q is significantly lower in SCI than in ND during AC, despite significantly greater values of HR. These findings also suggest that the disparity in exercise values of .Q is related to differences exhibited at rest.

Adult↗

PubMed2002

Peak exercise capacity of electrically induced ambulation in persons with paraplegia.

INTRODUCTION: Persons with spinal cord injury (SCI) are generally limited to exercise activities using the relatively smaller, less productive upper extremities with limited benefits as compared with leg exercise training. Functional electrical stimulation (FES) assisted ambulation has previously been demonstrated to allow persons with paraplegia to stand and ambulate limited distances. PURPOSE: This study compared the peak physiological responses of persons with paraplegia during FES ambulation and voluntary arm exercise. METHODS: Fifteen subjects (T -T ) previously habituated to FES ambulation, completed peak testing of both arm cranking (AC) and FES walking to the point of exhaustion. The AC tests were performed using a graded incremental protocol to exhaustion in 3-min stages and 10-W power output increments. The FES walking test consisted of successive 10-m walking bouts, each trial progressively increased in pace. Metabolic activity was continuously monitored via open-circuit spirometry with heart rate (HR) determined by a 12-lead electrocardiograph for AC and by direct palpation during FES. RESULTS: Peak VO(2) did not differ between AC (22.9 +/- 3.8 mL x kg x min(-1)) and FES (22.7 +/- 3.9 mL x kg x min(-1)). FES ambulation elicited significantly greater peak values of HR (191 beats x min(-1) versus 179 beats x min(-1)) and lower peak values of respiratory exchange ratio (1.06 vs 1.12) compared with AC. There were no significant differences in peak values of any other variables. CONCLUSION: This study indicates that FES ambulation performance, in persons with paraplegia, elicits similar exercise capacity, as indicated by similar peak oxygen consumption, as voluntary arm exercise.

Adult↗

PubMed2002

Physiological responses to high-speed, open-wheel racecar driving.

UNLABELLED: High-speed auto racing has been demonstrated to produce accelerated heart rate (HR) during competition. However, it has not been determined whether the increase in HR was due to physical work efforts or a result of emotional stress. PURPOSE: The purpose of this investigation was to examine the physiological responses associated with open-wheel automobile driving at competitive speeds. METHODS: Oxygen consumption and HR were assessed in seven professional automobile racing drivers during two incrementally paced driving sessions. A portable metabolic analyzer and EKG were directly attached to the subjects as they participated in driving tests on an oval speedway and a roadway course. Maximal physiological responses of the subjects were also determined during a graded treadmill test. RESULTS: During treadmill testing, maximal oxygen consumption (VO2max) ranged from of 42.0 to 59.7 mL x kg(-1) x min(-1) (mean +/- SD = 47.6+/-8.1). The road course and oval speedway testing at competitive speeds elicited mean VO2 values of 38.5 and 21.9 mL x kg(-1) x min(-1), respectively, which correspond to 79% and 45% of VO2max. Road course driving produced mean HR values of 152 beats x min(-1) with 142 beats x min(-1) recorded when driving at competitive speed on the speedway course. CONCLUSIONS: Professional open-wheel race drivers possess cardiorespiratory capacity similar to athletes participating in sports such as basketball, football, and baseball. The VO2 and HR responses to road course driving were similar to those previously reported in traditional sports settings. The findings of this study suggest that professional open-wheel racing drivers should be regarded as athletes that encounter significant physiological stresses.(2)

Adaptation, Physiological↗

PubMedDate not supplied

Effect of variable loading in the determination of upper-limb anaerobic power in persons with tetraplegia.

This article examines the effects of levels of resistance loading during arm Wingate Anaerobic Testing (WAnT) in persons with differing levels of cervical spinal cord injury (SCI). Thirty-nine persons with motor-complete SCI tetraplegia (13 each at C5, C6, and C7) performed six bouts of arm-crank WAnT with relative loads equivalent to 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 percent of body mass (BM). Power output was determined with the use of the SMI OptoSensor 2000 (Sports Medicine Industries, Inc., St. Cloud, MN, USA) hardware and software package. Values of peak power (P(peak)) and mean power (P(mean)) were examined statistically between groups (C5, C6, and C7) and across levels of resistance loading. Resistance loads that provided the greatest values of P(mean) for the three groups were as follows: C5 = 1.0 or 1.5 percent of BM; C6 = 1.5 or 2.0 percent of BM; and C7 = 2.5, 3.0, or 3.5 percent of BM. Appropriate loading for arm WAnT is specific to the level of tetraplegia and may provide a useful assessment of upper limb power production.

Adult↗

PubMedDate not supplied

Circuit resistance training in persons with complete paraplegia.

BACKGROUND/OBJECTIVE: We assessed the metabolic and heart rate (HR) responses to a single session of circuit resistance training (CRT) in six subjects with complete paraplegia (T5-T12 levels) in order to determine the caloric cost of the exercise. METHODS: Subjects underwent isoinertial weight training exercises with interspersed periods of high-cadence, low-resistance arm ergometry (AE). Following protocol familiarization, subjects completed one session of CRT during which continuous monitoring of HR, oxygen uptake (VO2), and respiratory exchange ratio (RER = VCO2/VO2) was performed. Caloric cost was calculated from the exercise VO2 values across the CRT session. A peak arm exercise test allowed data to be expressed as percentages of peak VO2 and HR. RESULTS: Subjects displayed mean VO2 values of 11.6 +/- 2.4 ml/kg/min (mean +/- SD) and a mean HR of 136 +/- 17 beats/min across the CRT session, corresponding with 49.0% of peak VO2 and 76.8% of peak HR. The RER values ranged from 0.96 to 1.19 and averaged above unity throughout the CRT session. CONCLUSION: Despite the modest absolute VO2 during exercise, CRT satisfies operational criteria developed for cardiorespiratory exercise prescriptions in persons without disability. The RER values recorded indicate that CRT is intense work that relies primarily on glycolytic metabolism.

Adult↗