Comparison study of treadmill versus arm ergometry

The Bruce treadmill test is used worldwide to assess cardiovascular disease. However, because of the high increments of intensity between the stages of this test, it is not best suited to a number of populations. Therefore, the aim of the study was to determine the difference between physiological outcomes of the arm crank test and Bruce treadmill test and to provide a regression equation to account for this. Thirty subjects (16 men and 14 women) performed both an arm crank test and the Bruce treadmill test, on two separate days, in a random order. Peak values of oxygen uptake (VO(2) ), respiratory exchange ratio (RER), ventilation rate (V(E) ), heart rate (HR) and ratings of perceived exertion (RPE) were recorded. Arm crank VO(2peak) and peak V(E) were significantly lower compared with treadmill VO(2peak) and peak VE, in both men and women (P<0·001). Arm crank HR(peak) was significantly lower than treadmill HR(peak) in men (P<0·001). The following is the regression equation to estimate treadmill: VO(2peak) = 0·8*arm crank VO(2peak) + 0·019*body weight + 2·025*gender-0·038*gender*body weight + 0·852, with gender being '0' for males and '1' for females. This model has a r(2) of 0·832 (SEE = 0·471). This strong correlation indicates that an accurate prediction of treadmill VO(2peak) can be made by arm crank VO(2peak) , which is a good estimate of a person's maximal oxygen uptake (VO(2max) ). Therefore, the arm crank test can be of great importance for evaluation of cardiovascular disease in many people.     

Is the high lactate release during arm exercise due to a low training status?

Summary To determine whether arm lactate release during arm exercise is related to the training status of the arms, seven arm-trained athletes were studied during 30 min of continuous arm exercise (AE) or leg exercise (LE) of increasing intensities corresponding to 30%, 50%, and 80% of peak VO₂ during AE and LE respectively. Blood vessels were catheterized for determination of regional blood flows and substrate exchanges. The respiratory exchange ratio was higher during AE than LE (P<0.01). The arteriovenous oxygen difference, [(A-V)O₂], for the leg during LE was 11–19% higher than the (A-V)O₂ for the arm during AE (P<0.01). At the highest intensity the (A-V)O₂ was 170±6 ml O₂1^-1 during LE, vs. 143 ± 9 during AE (P<0.01). Arm blood flow in relation to limb volume was 56–95% higher during AE (P<0.05). Arterial lactate concentrations were 27–60% higher during AE (P<0.01) and lactate release from the exercising limb was 2–4 times higher (P<0.05) during AE compared to LE. Adrenaline and noradrenaline rose 6- and 21-fold, respectively, during AE and did not differ from corresponding LE values. During AE the (A-V)O₂ difference across the arm, arterial lactate concentration, and arm lactate release were of the same magnitude in arm-trained and relatively less arm-trained subjects. Lactate release in relation to O₂ uptake by the exercising limb was 7–37% lower during AE in arm-trained subjects compared to AE in arm-untrained subjects but was 3–6 times higher than the corresponding relation during LE (P<0.01). We conclude that AE is associated with a larger lactate release compared to LE. This difference is only to a minor extent influenced by intense training of the arms. The high arm vs. leg lactate release appears to be associated with differences in regional circulatory adaptation by the exercising limb.     

Prediction of peak oxygen consumption from the ratings of perceived exertion during a graded exercise test and ramp exercise test in able-bodied participants and paraplegic persons

Al-Rahamneh HQ, Eston RG. Prediction of peak oxygen consumption from the ratings of perceived exertion during a graded exercise test and ramp exercise test in able-bodied participants and paraplegic persons.

Objective

To assess the accuracy of predicting peak oxygen consumption (Vo₂peak) from a graded exercise test (GXT) and a ramp exercise test during arm exercise in able-bodied persons and persons with paraplegia using ratings of perceived exertion (RPEs).

Design

Each participant performed a GXT (started at 30W and increased by 15W every 2min) and a ramp exercise test (started at 0W and increased by 15W·min⁻¹).

Setting

Universities' laboratories.

Participants

Able-bodied men (n=13; mean ± SD, 27.2±4.3y) and men with paraplegia (n=12; 31.1±5.7y). Six of the persons with paraplegia had flaccid paralysis as a result of poliomyelitis infection. The other 6 persons had complete spinal cord injuries with neurologic levels at and below T6.

Intervention

Not applicable.

Main Outcome Measures

Prediction of Vo₂peak by extrapolating submaximal oxygen consumption (V?o₂) and RPE values to RPE 20 on the Borg 6 to 20 RPE scale.

Results

This study showed a very strong linear relationship between RPE and V?o₂ during the GXT and the ramp test for able-bodied persons (R²≥.95 and R²≥.96, respectively) and persons with paraplegia (R²≥.96 and R²≥.95, respectively). There was no significant difference between measured and predicted Vo₂peak from RPEs before and including RPE 13, 15, and 17 during the GXT for persons with paraplegia (P>.05). For the able-bodied participants, there was no significant difference between measured and predicted Vo₂peak from RPEs before and including RPE 15 and 17 during the ramp exercise test (P>.05).

Conclusion

The GXT provided acceptable predictions of Vo₂peak for persons with paraplegia, and the ramp test provided acceptable predictions of Vo₂peak for able-bodied persons.     

Reference values for cardiopulmonary exercise testing in healthy adults: a systematic review

Reference values (RV) for cardiopulmonary exercise testing (CPET) provide the comparative basis for answering important questions concerning the normality of exercise response in patients and significantly impacts the clinical decision-making process. The aim of this study is to systematically review the literature on RV for CPET in healthy adults. A secondary aim is to make appropriate recommendations for the practical use of RV for CPET. Systematic searches of MEDLINE, EMBASE and PEDro databases up to March 2014 were performed. In the last 30 years, 35 studies with CPET RV were published. There is no single set of ideal RV; characteristics of each population are too diverse to pool the data in a single equation. Therefore, each exercise laboratory must select appropriate sets of RV that best reflect the characteristics of the population/patient tested, and equipment and methodology utilized.     

Assessment of anaerobic power to verify VO2max attainment

Across various populations, verification testing is used to confirm VO₂max attainment and has repeatedly shown similar VO₂max values to those obtained from incremental exercise. Yet, many individuals show meaningful differences in VO₂max between protocols, and an explanation for this is unknown. The aim of the study was to elucidate this phenomenon in 30 men and women of similar age, fitness, and physical activity using assessment of anaerobic power. On day 1, they completed the Wingate test, and returned at least 48 h later to complete incremental cycle ergometry followed by a verification protocol. During exercise, ventilation, pulmonary gas exchange data, and heart rate (HR) were continuously measured. Mean VO₂max was similar (P > 0·05) between protocols (42·05 ± 5·88 ml kg^?1 per min versus 42·03 ± 5·75 ml kg^?1 per min, respectively), although seven subjects (23%) revealed a VO₂max that was not ‘verified’ by the supramaximal protocol. Indices of power output and gas exchange data were similar (P > 0·05) between subjects who revealed a ‘true’ VO₂max compared to those who did not, although peak and mean power was consistently higher in persons whose VO₂max was not ‘verified.’ A previously established HRmax criterion for verification testing was not met in 17% of subjects. Additional study is merited to identify alternate determinants of VO₂max, such as muscle activation via assessment of motor unit recruitment, and to investigate utility of verification testing to confirm VO₂max attainment in elite athletes and the elderly.     

Effects of chronic dobutamine administration on the response to acute exercise in dogs

Summary. The effects of chronic dobutamine administration on haemodynamic and metabolic responses to submaximal and maximal exercise were studied in dogs. Dobutamine was infused at a rate of 40 μg/kg min^-1, 2 h day^-1, 5 days week^-1 for a period of 6 weeks. Acute infusion of dobutamine for 1 h increased heart rate by 73 ± 30 beats min^-1 and cardiac output by 143 ± 141 ml/min kg^-1, reduced mean arterial blood pressure by 12 ± 10 mmHg and arterial-venous O₂ difference by 1.5 ± 1 vol%. Maximal oxygen consumption, heart rate, stroke volume, cardiac output and arterial-venous O₂ difference were unchanged after 6 weeks of treatment. Reductions in heart rate at rest and during submaximal exercise following chronic dobutamine treatment were small and significant only at the lowest exercise level studied. Mixed venous lactate concentrations measured at rest, during submaximal and maximal exercise and at 2 min of recovery were not different after dobutamine treatment. Chronic dobutamine infusion did not change the citrate synthase activity in the lateral gastrocnemius muscle. These results suggest that chronic dobutamine therapy in healthy dogs does not produce aerobic training responses.     

负荷运动对能量代谢的影响及研究

目的探讨渐增负荷最大运动后的过量氧耗与血乳酸、血糖及氨基酸代谢的变化关系。方法受试者为10名男子健康大学生。采用活动跑台方法进行渐增负荷跑至力竭为止。结果运动结束30min,吸氧量恢复到安静水平时,血乳酸浓度仍比安静时水平高,运动中丙氨酸上升,运动结束30min丙氨酸减少,但并未恢复到安静时的水平。结论过量氧耗除用于血乳酸的消耗外,可能生要用于丙氨酸代谢中的糖新生。     

Comparison of COSMED’S FitMate™ and K4b2 metabolic systems reliability during graded cycling exercise

Abstract

This study compared the reliability of the Cosmed FitMate? and K4b2 metabolic systems during light to heavy steady state exercise. Expired gas, ventilation were recorded in 50 subjects, using in a random order among four sessions, either the FitMate? or the Cosmed K4b2. No differences in oxygen consumption were observed between the two systems whatever the intensity. Intraclass correlation were high for both analyzers (respectively for the FitMate? system and the Cosmed K4b2; ICC: 0.76–0.88 vs. 0.88–0.95). The FitMate? metabolic system could be a useful reliable and easy-to-use metabolic system in energy expenditure measurement.     

Validation of a single‐stage fixed‐rate step test for the prediction of maximal oxygen uptake in healthy adults

Healthcare professionals with limited access to ergospirometry remain in need of valid and simple submaximal exercise tests to predict maximal oxygen uptake (VO_2max). Despite previous validation studies concerning fixed‐rate step tests, accurate equations for the estimation of VO_2max remain to be formulated from a large sample of healthy adults between age 18–75 years (n > 100). The aim of this study was to develop a valid equation to estimate VO_2max from a fixed‐rate step test in a larger sample of healthy adults. A maximal ergospirometry test, with assessment of cardiopulmonary parameters and VO_2max, and a 5‐min fixed‐rate single‐stage step test were executed in 112 healthy adults (age 18–75 years). During the step test and subsequent recovery, heart rate was monitored continuously. By linear regression analysis, an equation to predict VO_2max from the step test was formulated. This equation was assessed for level of agreement by displaying Bland–Altman plots and calculation of intraclass correlations with measured VO_2max. Validity further was assessed by employing a Jackknife procedure. The linear regression analysis generated the following equation to predict VO_2max (l min^?1) from the step test: 0·054(BMI)+0·612(gender)+3·359(body height in m)+0·019(fitness index)?0·012(HRmax)?0·011(age)?3·475. This equation explained 78% of the variance in measured VO_2max (F = 66·15, P<0·001). The level of agreement and intraclass correlation was high (ICC = 0·94, P<0·001) between measured and predicted VO_2max. From this study, a valid fixed‐rate single‐stage step test equation has been developed to estimate VO_2max in healthy adults. This tool could be employed by healthcare professionals with limited access to ergospirometry.     

Repeatability of measurements of oxygen consumption,heart rate and Borg's scale in men during ergometer cycling

The coefficient of repeatability (COR), expressed as 2-SD of differences, was calculated between two measurements of oxygen consumption (V O2), heart rate (HR) and rating of perceived exertion (RPE) during ergometer cycling by men. The two sets of measurements were performed 5 to 6 weeks apart. Nineteen healthy men performed an incremental maximal exercise test on an ergometer cycle. The load started at 50 W and increased by 5 W 20 s-1 until exhaustion was reached. At 40% of the individual maximum load of the pretest, the load was kept constant for 4 min in order to reach steady state. Gas measurements were recorded continuously by computerized instrumentation. The HR was monitored with electrocardiography (ECG) and the perceived exertion was evaluated using Borg's scale. The COR of V O2 at sub-maximal load was 14% and at maximum load 11%. The values in absolute figures were 209 and 332 ml min-1. The corresponding COR of the HR was 16% at sub-maximum load and 6% at maximum load, and an evaluation of the perceived exertion yielded CORs in absolute values of 4.8 and 1.3, respectively. The COR for V O2, HR and ratings of perceived exertion when cycling on an ergometer cycle thus indicate a better agreement between the measurements at maximum load. The COR of the heart at sub-maximal loads must be kept in mind when using HR for estimation of V O2max. The reported findings should be considered when using tests on an ergometer cycle for evaluating exercise capacity.     

Effect of exercise intensity on oxygen consumption kinetics in non-exercising muscle during exercise

This study examined the effect of exercise intensity on the kinetics of muscle oxygen consumption in non-exercising forearm flexor muscles (VO(2mf)) during exercise. Seven healthy male subjects performed cycling exercise for 60 min at 30% of maximal oxygen consumption (%VO(2max)) and 30 min at 50% VO(2max) on separate days. The VO(2mf) values at rest and during exercise were measured by near-infrared spectroscopy. The VO(2mf) at 30% VO(2max) significantly increased to 1·2 ± 0·1-fold over resting value at 20 min after the beginning of exercise (P<0·05) and remained constant within 1·2- to 1·3-fold over resting value until 60 min during exercise. The VO(2mf) at 50% VO(2max) significantly increased to 1·2 ± 0·1-fold over resting value at 15 min after the beginning of exercise (P<0·05). Subsequently, the VO(2mf) at 50% VO(2max) increased with time to 1·3 ± 0·1-fold over resting value at 20 min after the beginning of exercise and to 1·5 ± 0·2-fold over resting value at 30 min. The VO(2mf) 15-30 min of exercise at 50% VO(2max) was significantly higher than that at 30% VO(2max) (P<0·05). These data suggest that the increase in VO(2mf) has a time lag from the beginning of exercise, and the kinetics of VO(2mf) during exercise differs with exercise intensity. Therefore, we conclude that the kinetics of VO(2mf) during exercise is dependent on exercise intensity.     

Influence of work rate on the determinants of oxygen deficit during short-term submaximal exercise: implications for clinical research

Objective: The effect of increasing work rate was studied on the determinants of the oxygen deficit. Methods: Exercise testing was performed on a treadmill and gas exchange was measured on a breath‐by‐breath basis. Eleven healthy subjects, aged 18–25 years, performed three square wave exercise tests of different intensity. Before exercise, gas exchange was measured at rest in the standing position for 3 min, followed by a 6‐min square wave exercise test, randomly assigned at 4, 8 or 12% inclination. Immediately after exercise the recovery gas exchange was determined for 3 min. To calculate oxygen deficit, the oxygen uptake (O₂) values at onset of exercise were subtracted from the steady‐state value, the differences were cumulated and expressed as a percentage of the total oxygen cost for the 6‐min exercise. Results: The oxygen deficit increased significantly (P<0·001) with increasing work rate (6·1 ± 1·4% for 4%, 8·4 ± 2·1% for 8% and 9·4 ± 1·7% at 12% inclination). This resulted from a somewhat slower increase of O₂ at the onset of exercise at the highest work rate, reflected by a significantly higher time constant for O₂ at 8 and 12% (24·6 ± 7·3 s at 8% and 24·1 ± 6·3 s at 12% versus 20·2 ± 8·1 s at 4%). More importantly a significantly higher steady‐state value for O₂ was found at the highest exercise level, compared with the other exercise intensities. Conclusion: The higher oxygen deficit at the highest level of exercise is determined by a slower time constant and a higher asymptote value for O₂.     

The effects of menstrual cycle phase on the incidence of plateau at and associated cardiorespiratory dynamics

The purpose of this study was to examine the effect of menstrual cycle phase on maximal oxygen uptake () and associated cardiodynamic responses. A total of 16 active females volunteered of which n = 10 formed the non‐oral contraceptive pill group (n‐OCP), displaying a regular menstrual cycle of 28·4 ± 2·2 days (age 20·6 ± 1·6 years, height 169·9 ± 6·4 cm, mass 68·7 ± 7·9 kg) and n = 6 formed the oral contraceptive pill group (OCP) (monophasic pill) (age 21·7 years ± 2·16, height 168·1 cm ± 6·8 cm, mass 61·6 ± 6·8 kg). Each completed four incremental exercise tests for determination of , cardiac output, stroke volume and heart rate. Each test was completed according to the phases of the menstrual cycle as determined through salivary analysis of 17‐β oestrodiol and progesterone. Non‐significant differences were observed for across phases and between groups (P>0·05) with additional non‐significant differences for , HR_max and SV_max between groups. For ? during the final 60 s of the trial, significant differences were observed between OCP and n‐OCP (P<0·05) with OCP showing zero plateaus in three pseudo‐phases. Significant difference observed for a‐vO_2dif n‐OCP between premenstruation and menstruation at 30–100% (P<0·05). Data suggest that the ‐plateau is effected by monophasic oral contraceptive pill, furthermore these data imply that test outcome is independent of menstrual cycle phase but caution should be applied when evaluating maximal oxygen uptake in females who are administered a monophasic oral contraceptive pill.     

约束手臂摆动对健康青年人步态时空参数的影响

目的:明确约束手臂摆动对健康青年人步态时空参数的影响,探讨手臂摆动在步行中的作用。方法:选取健康青年人36例,其中男性18例,女性18例,平均年龄(22.72±3.54)岁,平均身高(167.35±9.15)cm,平均体重(63.62±16.29)kg。利用Gait Watch三维步态分析系统采集受试者在自然步态、双臂体侧、双臂体前、双臂体后、左臂体侧、左臂体前、左臂体后、右臂体侧、右臂体前、右臂体后共10种状态下的步态时空参数。不同约束状态均随机进行测试。分析不同约束手臂状态下步态时空参数同自然步态之间的差异。结果:不同手臂约束摆动状态下,步态周期、步频、步幅、步速、左步长、右步长、双支撑相同自然步态相比差异无显著性意义(P0.05)。左臂体侧、左臂体前、左臂体后三种约束条件下左支撑相、左摆动相同自然步态相比差异有显著性意义(P0.05);左臂体后、右臂体侧、右臂体前、右臂体后四种手臂约束条件下右支撑相、右摆动相与自然步态相比差异有显著性意义(P0.05)。结论:约束左侧手臂摆动后左下肢支撑相时间缩短,摆动相时间延长;约束右侧手臂摆动后右下肢支撑相时间延长,摆动相时间缩短。     

心肺复苏机械通气时选择不同流速模式对气道峰压的影响

目的：观察心肺复苏（CPR）期间在胸外按压情况下的机械通气方式,探讨呼吸机送气流速模式选用方波（恒流）和减速波（递减波）对患者气道压力的影响。方法采用前瞻性自身配对设计方案,选择浙江省丽水市中心医院急诊科2011年1月至2013年2月序贯收治的40例CPR患者。使用伟康Eisprit呼吸机,常规设定的呼吸机工作其他参数不变,由同一医护人员给予患者的胸外按压进入稳定状态后,呼吸机流速模式先后使用方波和减速波,冻结时间-压力曲线后测量气道峰压的最高值并记录为一对数据。每例患者取不同按压者操作时的2对数据,40例患者共获得80对数据,通过自身配对t检验进行统计学分析。结果使用减速波时平均气道峰压最高值为（38.15±5.99）cmH2O（1 cmH2O＝0.098 kPa）,比方波的（43.86±6.68）cmH2O减低了（5.71±1.98）cmH2O,且差异有统计学意义（t＝22.010,P＝0.000）。使用方波时有73.75%的患者气道峰压最高值会超过40 cmH2O,而使用减速波只有45.00%的患者气道峰压最高值会超过40 cmH2O。结论 CPR机械通气时,因使用减速波比方波能明显减低气道峰压,从而减轻气压伤的发生,减少呼吸机触发高压报警的概率,因而可提高呼吸机使用的依从性,故减速波是比方波更为合适的流速模式。     

The effect on body composition and exercise performance of home parenteral nutrition when given as adjunct to chemotherapy of testicular carcinoma

This study has evaluated whether long-term and permanent total parenteral nutrition (TPN) can protect body composition and exercise capacity during iterated courses of chemotherapy (PVB) in men with testicular carcinoma. Thirty-three men were randomly allocated by means of a computer based algorithm to receive either TPN (at hospital and home) during the entire chemotherapy period or to rely on spontaneous oral intake only. Nutrition status was assessed by measurements of whole body nitrogen (neutron activation), total body potassium, body water, urine creatinine excretion, loco-regional body nutrition indexes (AMC, TSF) and biochemical plasma concentrations (albumin, thyroid hormones). Whole body respiratory gas exchanges were measured during resting, submaximal and maximal exercise. TPN was prescribed on an individual basis in all study patients to cover 150% of their measured caloric need; nitrogen was given as 0.2 g N kg-1 day. All individuals were allowed to eat freely throughout the study. TPN patients were in overall positive energy balance (+850 Kcal day-1), while the control group was in negative balance (-532 Kcal day-1). This led to weight gain in the TPN group (+2.2 +/- 1.0 kg) while the control group lost significant weight (-4.2 +/- 1.1 kg). The average spontaneous oral caloric intake was 1014 +/- 153 Kcal day-1 in the TPN group and 1484 +/- 200 Kcal day-1 in the control group; total protein intake corresponded to 1.5 g protein kg day-1 in the TPN group and 0.7 kg day-1 in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)