Ergometer modification for combined arm-leg use by lower extremity amputees in cardiovascular testing and training

A commercial arm-leg ergometer was adapted so that combined bilateral arm-single leg work could be performed by unilateral lower extremity amputees from their own wheelchairs. Three middle-aged to elderly unilateral amputees performed progressive discontinuous bilateral arm crank and combined bilateral arm-single leg cycle exercise tests on the same air-braked ergometer adapted for either form of ergometry. Select amputees may achieve greater peak oxygen uptakes (VO2), power outputs (PO), and heart rates (HR) during combined bilateral arm-single leg cycle testing versus bilateral arm crank testing. Following 14 weeks of combined arm-leg training on the modified ergometer, a 73-year-old above-knee amputee demonstrated peak VO2 and PO increases of 25% (+3.8 mL X kg-1 X min-1) and 33% (+25W) respectively. Combined arm-leg ergometry as described herein may activate the largest available muscle mass and elicit the greatest oxygen uptake during exercise testing. In addition this exercise modality may simultaneously condition the arms and leg, providing functional gains in both wheelchair propulsion and prosthetic ambulation.     

Ventilatory efficiency and rate of perceived exertion in obese and non-obese children performing standardized exercise

Sixty children, in the age span 6-17 years originally divided into two groups, matched by age, sex and height--30 obese subjects [15 girls/15 boys; body mass index (BMI) = 27.4 +/- 4.5 m kg-2; ideal body weight (IBW) range = 122-185%] and 30 controls (BMI = 18.8 +/- 2.7 m kg-2) performed incremental treadmill exercise test. Perceived exertion was assessed by means of Category-Ratio Borg scale. The duration of the exercise for the children in the obesity group was significantly shorter than controls (P = 0.010) but obese children have greater absolute values for oxygen uptake (VO2peak ml min-1 = 1907 +/- 671 versus 1495 +/- 562; P = 0.013) and ventilatory variables (VE, VT), which adjusted for body mass decrease significantly (VO2/kg ml min-1 kg-1 = 29.2 +/- 3.8 versus 33.6 +/- 3.5; P < 0.001). Among the various methods for 'normalizing' absolute values of VO2peak for body size, dividing it by body surface area (BSA) yielded the best results (VO2/BSA ml min-1 m-2 = 43.5 +/- 4.6 versus 44.7 +/- 5.6; P = 0.335). The ventilatory efficiency determined either as a slope of VE versus VCO2 or as a simple ratio at anaerobic threshold did not differ between obese and non-obese children in the incremental and recovery periods of exercise. There was a negative correlation of VE/VCO2 slope with age and anthropometric parameters. Obese children rated perceived exertion significantly higher than controls despite the standard workload (Borg score = 6.2 +/- 1.2 versus 5.2 +/- 1.1; P = 0.001). In conclusion, the absolute metabolic cost of exercise is higher in the obesity group compared with the control subjects. Both groups have similar ventilatory efficiency but an increased awareness of fatigue that furthermore limits their physical capacity.     

Calorimetric validation of the Caltrac accelerometer during level walking

The primary purpose of this study was to compare the Caltrac accelerometer output with measured energy expenditure (Ee). Twenty-five volunteers (10 men, 15 women) walked on a level motor-driven treadmill at four different speeds (54, 81, 104, and 130 m.min-1) with the Caltrac device affixed to the waistline. Each of the four experimental trials lasted eight minutes, and the testing was completed within an hour. During the test, oxygen consumption (VO2) (in L.min-1 and in mL.kg-1.min-1) and nonprotein respiratory exchange ratio were monitored by the Beckman Horizon metabolic cart. The accelerometer output at the end of each exercise bout was also monitored and subsequently divided by 8 to convert the readings to counts.min-1. The mean VO2 (L.min-1) at steady state (ie, 6th-8th minutes of exercise) was converted to a caloric value. We obtained a moderate correlation coefficient (r) of .76 between the accelerometer output and the VO2 (mL.kg-1.min-1) and a high correlation coefficient of .92 between the Ee and the accelerometer readings. The Caltrac accelerometer output (counts.min-1) was significantly higher (p less than .01) than the Ee (kcal.min-1) at the four walking speeds. The difference between the accelerometer output and the Ee ranged from 13.3% to 52.9%. The data were further analyzed with linear, polynomial, multiple, and stepwise regression models. The results of the analyses revealed that the Caltrac accelerometer output is a valid predictor of Ee during level walking when the appropriate regression equation is used to adjust the values.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maximal exercise testing of mentally retarded adolescents and adults: reliability study

Few data are available regarding maximal exercise testing of mentally retarded individuals. No data are available on the reliability of maximal exercise testing of mentally retarded individuals. The purpose of this study was to determine the reliability of graded exercise testing of mentally retarded adolescents and adults. The testing was conducted at two geographically different centers. At Center A, 14 mentally retarded adolescents (11 boys, three girls) with Down syndrome, who were educable or trainable, were recruited from a nonresidential school. The subjects completed two Balke-Ware treadmill protocols until exhaustion. The treadmill time and heart rate (HR) were recorded. The time between tests was approximately one week. At Center B, 21 mentally retarded adults (14 women, seven men means IQ = 56) were recruited from local workshops and group homes. These subjects completed a treadmill walking protocol, with metabolic measurements, until exhaustion. The time between tests varied from one to four months. At Center A, the subjects achieved a mean treadmill time of 8.72min on test one and 8.84min on test two (means HR = 174 and 175bpm, respectively). The reliability coefficient between the two tests was .94. At Center B, the subjects achieved a mean V0(2)max of 27.2mL.kg-1.min-1 on test one and 26.9mL.kg-1.min-1 on test two. The reliability coefficient was .93. These data show that maximal exercise testing is reliable for these populations of mentally retarded individuals, exhibiting similar values to their nonretarded peers.     

Graded exercise testing of mentally retarded adults: a study of feasibility

There is a striking absence of data on the cardiovascular fitness of mentally retarded adults and what limited data are reported reflect field or submaximal laboratory tests. This study sought to develop a protocol that would allow maximal aerobic testing (VO2max) of mentally retarded adults in the laboratory. Of 21 subjects recruited, 17 (eight men and nine women) were successfully tested. Their mean IQ (+/- SD) was 52.68 +/- 16.3; their weight was 149.76 +/- 35.3 lbs, height 64.4 +/- 4.2 in, and age 29.29 +/- 6.6 yr. The testing occurred in three phases: (1) familiarization with the laboratory environs; (2) training to walk on the treadmill and breathe through the respiratory collection system; and (3) data collection via graded exercise testing. The treadmill protocol consisted of walking at 3 mph at 0% grade for two minutes, followed by 3 mph at a 2.5% grade for two minutes. The speed was then held constant at 3 mph and the grade increased 2.5% every minute until exhaustion. Metabolic data were collected every minute using a Beckman MCC cart connected to the subjects through a Hans-Rudolph valve. Heart rates (HR) were collected with a Quinton electrocardiograph. The mean maximal cardiorespiratory data were as follows (+/- SD):VO2max = 26.3 +/- 8.0 ml X kg-1 X min-1; HRmax = 171 +/- 14 beats/min; VEmax = 62.8 +/- 21.8 L/min; and respiratory quotient (R) = 1.09 +/- .07. The R values obtained were within an acceptable range for valid maximal data. In addition, 15 subjects produced supramaximal work and showed a decline in VO2 during the last minute of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

心房颤动对微创二尖瓣术后患者静态肺功能及运动耐量的影响

目的:探究房颤对微创二尖瓣术后患者的静态肺功能及运动耐量水平的影响。方法:微创二尖瓣术后患者30例,按有无房颤分为两组,各15例,两组间基本情况保持均衡。所有患者在2013年1月1日至2014年9月30日期间进行静态肺功能及症状限制的极量心肺运动测试。肺功能由用力肺活量、第一秒用力呼气量、两者实测值分别占预计值的百分比,及1秒率表示;运动耐量用峰值时公斤摄氧量(peak VO2/kg),表示,通气效率用无氧阈时二氧化碳通气当量(VE/VCO2@AT)表示。结果:房颤组表现为轻度限制性肺通气障碍,而窦律组平均肺通气功能正常;房颤组运动耐量水平显著低于窦律组,两组peak VO2/kg分别为17.34±2.82 ml·kg-1·min-1、20.35±4.13 ml·kg-1·min-(1P=0.03);两组间VE/VCO2@AT也有显著性差异(34.48±4.16 vs 29.80±4.51,P0.01)。结论:二尖瓣术后合并房颤的患者,其肺容积及运动耐量明显低于窦律的患者,运动耐量下降的主要机制为心排血量减少。     

Prosthetic rehabilitation of geriatric amputee patients: a follow-up study

During a four-year period, 116 lower extremity amputee patients older than 65 years were evaluated and treated by our department. Fifty-nine patients with below-knee (BK) amputations, 22 with above-knee (AK) amputations, and 15 with bilateral amputations were fitted with prostheses and trained in their use. A follow-up study on all patients was done at an average of 22 months after they had completed their training program but not earlier than after 6 months. Of all BK amputees who had been fitted with a prosthesis, 73% were using it fulltime and as their main mode of locomotion; 25% were using it part of the time. The results were less favorable for AK and for bilateral amputee patients: 50% of AK amputees and 33% of the bilateral amputees had become fulltime users of their prostheses. Age alone was not a major determining factor in success or failure of prosthetic rehabilitation. Failures usually were due to concurrent medical disease or mental deterioration. The study indicates that the effort and expense of fitting and training geriatric patients with prostheses may be well worthwhile.     

The validity of the Computer Science and Applications activity monitor for use in coronary artery disease patients during level walking

The principal aim of the present study was to examine the validity of the Computer Science and Applications (CSA) activity monitor during level walking in coronary artery disease (CAD) patients. As a secondary aim, we evaluated the usefulness of two previously published energy expenditure (EE) prediction equations. Thirty-four subjects (29 men and five women), all with diagnosed CAD, volunteered to participate. Oxygen uptake (VO2) was measured by indirect calorimetry during walking on a motorized treadmill at three different speeds (3.2, 4.8 and 6.4 km h-1). Physical activity was measured simultaneously using the CSA activity monitor, secured directly to the skin on the lower back (i.e. lumbar vertebrae 4-5) with an elastic belt. The mean (+/- SD) activity counts were 1208 +/- 429, 3258 +/- 753 and 5351 +/- 876 counts min-1, at the three speeds, respectively (P < 0.001). Activity counts were significantly correlated to speed (r = 0.92; P < 0.001), VO2 (ml kg-1 min-1; r = 0.87; P < 0.001) and EE (kcal min-1; r = 0.85, P < 0.001). A stepwise linear regression analysis showed that activity counts and body weight together explained 75% of the variation in EE. Predicted EE from previously published equations differed significantly when used in this group of CAD patients. In conclusion, the CSA activity monitor is a valid instrument for assessing the intensity of physical activity during treadmill walking in CAD patients. Energy expenditure can be predicted from body weight and activity counts.     

The effect of steering on the physiological energy cost of wheelchair propulsion

Previous studies of the energy cost of wheelchair propulsion have used ergometers or tracks requiring little steering. We have measured minute ventilation (VE), oxygen consumption (VO2), carbon dioxide output (VCO2) and heart rate (HR) during exercise in a two arm, hand-rim propulsion wheelchair on a treadmill, and on three tracks of increasing tortuosity in eight able-bodied subjects. During propulsion at 0.6 m/sec, VE, VO2, and VCO2 were significantly greater on the track with the maximal steering component than on that with the minimal steering component, or on the treadmill with no steering component. Heart rate was significantly higher on the maximal compared to minimal steering component track. Exercise at speeds varying from 0.2 to 1.0 m/sec showed that VO2 and VCO2 were significantly higher on the medium steering component track than on the treadmill at speeds of 0.6 m/sec and above. We conclude that the effort of steering contributes significantly to the energy cost of wheelchair propulsion particularly at higher speeds.     

Oxygen consumption and heart rate responses during five active exercises

Oxygen consumption (VO2) and heart rate (HR) responses during five active exercises from a cardiac rehabilitation program were measured in 12 healthy female subjects aged 20 to 30 years. The VO2 value was determined by collecting expired gases using an open-circuit method. Resting HR and VO2 values were established while the subjects were positioned supine for 10 to 20 minutes. Exercise values were recorded while the subjects performed five different active exercise bouts consisting of various combinations of upper and lower extremity range-of-motion exercises in the supine or semi-Fowler positions. These exercises were adopted from a stage 1 bedside cardiac rehabilitation program. These activities resulted in low cardiovascular responses: an HR increase of less than 8 bpm and a VO2 increase of less than 2.0 mL X kg-1 X min-1.     

吸入沙美特罗替卡松对中重度慢性阻塞性肺疾病患者运动耐力的影响

目的 通过对吸入沙美特罗替卡松粉(SFC)治疗中重度慢性阻塞性肺疾病(COPD)患者进行研究,探讨吸入糖皮质激素联合长效β2受体激动剂对中重度COPD静息肺功能和运动耐力的影响.方法 选择稳定期的中重度COPD患者53例,随机分为治疗组与对照组.治疗组吸入SFC(每泡含沙美特罗50μg,丙酸氟替卡松250 μg),每日2次,每次1喷,对照组给予一般治疗.24周后,观察患者肺功能(PFT)及心肺运动试验(CPET)各项生理参数指标的变化.结果 试验开始时,治疗组与对照组的PFT参数与CPET参数相比较,无统计学差异.SFC治疗24周后,治疗组的静态肺功能指标显示,患者用力肺活量(FVC)由治疗前(2.5±0.6)L增加至(3.0±0.5)L,第一秒用力呼气量(FEV1)由治疗前(1.1.4±0.4)L增加至(1.3±0.2)L,深吸气量(IC)由治疗前(1.9±O.4)L增加至(2.2±0.5)L,胸廓内气量(ITGV)由治疗前(5.8±0.6)L减低至(5.1±0.7)L,残气量(RV)由治疗前(4.8±0.7)L减低至(4.0±0.8)L,肺总量(TLC)由治疗前(7.6±1.1)L减低至(7.3±1.0)L,差异均有统计学意义;CPET发现,峰值功率(Peak WR)由治疗前(86.2±13.5)watt增加至(91.2±15.1)watt,稍有改善,但无显著的统计学差异;峰值摄氧量(Peak VO2)由治疗前(1341.2±261.4)ml/min增加至(1796.0±282.5)ml/min,峰值公斤摄氧量(Peak VO2/kg)由治疗前(20.7 ±5.0)ml·min-1·kg-1增加至(23.5±4.4)ml·min-1·ks-1,Peak VCO2由治疗前(1671.4±254.3)ml/min增加至(1995.1±241.7)ml/min,峰值氧脉搏(Peak O2 pulse)由治疗前(7.5±2.3)ml/beat增加至(10.9±2.7)ml/beat,峰值通气量(Peak VE)由治疗前(31.2±10.2)L/min增加至(37.2±9.2)L/min,死腔/潮气量(VD/VT)由治疗前(39.4±7.0)%减低至(32.4±6.1)%,二氧化碳通气当量最低值(Lowest VE/VCO2)由治疗前32.5±3.2减低至28.8±2.9;PET中IC改善值与CPET中Peak VO2、Peak VO2/ks、Peak VE、VD/VT、Lowest VE/VCO2:等的改善值有良好的相关性,而FEV1的改善值与上述CPET的参数改善无显著相关.对照组用药前后,患者PFT及CPET各参数无明显的变化.结论 中重度COPD患者的运动耐力显著减低,长期使用SFC后,其气流受限的改善程度有限,峰值运动功率仅有轻微改善,但患者的静息及运动时的肺过度充气状态明显减轻,通气/血流匹配状况明显好转,通气效率得到显著改善,从而提高运动耐受能力.     

Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user’s nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking. We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head) and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius) of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step inter-subject variability of these profiles by calculating variance-to-signal ratios. We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects. Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee’s nervous system.     

Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

ABSTRACT: BACKGROUND: Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user's nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking. METHODS: We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head) and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius) of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step intersubject variability of these profiles by calculating variance-to-signal ratios. RESULTS: We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects. CONCLUSION: Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee's nervous system.     

The "Low Intensity Treadmill Exercise" Protocol for Appropriate Rate Adaptive Programming of Minute Ventilation Controlled Pacemakers

The objective of rate adaptive pacemakers that measure minute ventilation by tmnsthoracic impedance is to simulate the physiological relationship of the sensed signal to the sinus node response during exercise, thus achieving an appropriate matching of heart rate with patient effort. The purpose of this study was to determine the physiological relationship between heart rate and minute ventilation (HR/VE) during peak exercise testing in order to develop a database for appropriate rate adaptive slope programming of minute ventilation controlled pacemakers. Due to several clinical limitations of peak exercise testing, it was additionally determined whether the 35-watt “low intensity treadmill exercise” (LITE) protocol can be used as a substitute for peak exercise test using the “ramping incremental treadmill exercise” (RITE) protocol in order to assess the correct HR/VE slope below the anaerobic threshold. The stress tests were performed on a treadmill with the collection of breath-by-breath gas exchange. Linear regression analysis was used to determine the HR/VE slope below and above the anaerobic threshold and during the early, dynamic phase of low intensity exercise with the RITE and LITE protocols, respectively. The results of this testing in 41 healthy subjects demonstrated that the HR/VE relationship throughout treadmill exercise using the RITE protocol was not linear but curvilinear in nature, with a steeper HR/VE slope of 1.54 ± 0.51 below versus 1.15 ± 0.37 above the anaerobic threshold (P < 0.005). The HR/VE slope determined during the early, dynamic phase of the LITE protocol (1.58 ± 0.88) did not differ from the HR/VE slope from rest to anaerobic threshold obtained using the peak exercise RITE test (1.54 ± 0.51; P = 0.79), Rate adaptive pacing should simulate the curvilinear relationship between heart rate and minute ventilation from rest to peak exercise. The HR/VE slope determined during the early, dynamic phase of low intensity exercise represents the HR/VE slope derived from the RITE protocol below the anaerobic threshold. According to the peak exercise database, the slope above anaerobic threshold can easily be calculated as a percentage of the slope below the anaerobic threshold. The LITE protocol can, therefore, be effectively performed as a substitute for peak exercise stress tests to determine the correct pacemaker rate response factor in order to obtain a physiological heart rate to minute ventilation relationship for the appropriate matching of paced heart rate with patient effort.     

Physiological and symptomatic responses to cycling and walking in intermittent claudication

To shed light on the potential efficacy of cycling as a testing modality in the treatment of intermittent claudication (IC), this study compared physiological and symptomatic responses to graded walking and cycling tests in claudicants. Sixteen subjects with peripheral arterial disease (resting ankle: brachial index (ABI) < 0.9) and IC completed a maximal graded treadmill walking (T) and cycle (C) test after three familiarization tests on each mode. During each test, symptoms, oxygen uptake (VO2), minute ventilation (VE), respiratory exchange ratio (RER) and heart rate (HR) were measured, and for 10 min after each test the brachial and ankle systolic pressures were recorded. All but one subject experienced calf pain as the primary limiting symptom during T; whereas the symptoms were more varied during C and included thigh pain, calf pain and dyspnoea. Although maximal exercise time was significantly longer on C than T (690 +/- 67 vs. 495 +/- 57 s), peak VO2, peak VE and peak heart rate during C and T were not different; whereas peak RER was higher during C. These responses during C and T were also positively correlated (P < 0.05) with each other, with the exception of RER. The postexercise systolic pressures were also not different between C and T. However, the peak decline in ankle pressures from resting values after C and T were not correlated with each other. These data demonstrate that cycling and walking induce a similar level of metabolic and cardiovascular strain, but that the primary limiting symptoms and haemodynamic response in an individual's extremity, measured after exercise, can differ substantially between these two modes.     

Amputation: energy cost of ambulation.

A mobile instrument system was used to measure energy consumption by indirect calorimetry at rest and during ambulation in 25 unimpaired subjects, 6 unilateral below-knee (BK) amputee patients, 6 unilateral above-knee (AK) amputee patients and 4 bilateral AK amputee patients. To prevent the introduction of gait difficulties among the impaired subjects, each subject was permitted to walk at his own comfortable speed. Since speed thus varied among subjects, ambulation data were expressed in units of energy per foot traveled. Statistical analyses of the mean oxygen costs indicated several significant differences among the groups. In comparison to unimpaired subjects, the mean oxygen consumption was 9% higher in unilateral BK amputee patients, 49% higher in unilateral AK amputee patients and 280% higher in bilateral AK amputee patients.     

Effect of marihuana on cardiorespiratory responses to submaximal exercise.

Six male chronic marihuana (MH) users exercised on a bicycle ergometer for 15 min at approximately 50% VO2max under 3 conditions: (1) not smoking (control), (2) after smoking MH containing 7.5 mg (-) delta-9-tetrahydrocannabinol, and (3) after smoking placebo marihuana (PL). The MH was administered double-blind in a counterbalanced repeated-measures design. Heart rates (HRs), arterial blood pressures (BPs), pulmonary ventilation (VE), and oxygen uptake (VO2) were measured during exercise and 15 min recovery. PL had no effect on any of the physiologic variables. Smoking MH had no effect on systolic blood pressure (SBP), diastolic blood pressure (DBP), VE, or VO2, but did induce a marked increase in heart rate which persisted throughout exercise and recovery periods, averaging 34% higher than control values at rest, 18% higher during exercise, and up to 50% higher during recovery. MH smoking increased the product of HR x SBP in all circumstances.