Reliability and Responsiveness of Cardiopulmonary Exercise Testing in Fatigued Persons with Multiple Sclerosis and Low to Mild Disability

Background

Peak oxygen uptake (VO₂peak) via cardiopulmonary exercise testing is considered the gold standard for testing aerobic capacity in healthy participants and people with various medical conditions. The reliability and responsiveness of cardiopulmonary exercise testing outcomes in persons with MS (PwMS) have not been extensively studied.

Objective

(1) to investigate the reliability of cardiopulmonary exercise parameters in PwMS; (2) to determine the responsiveness, in terms of the smallest detectable change (SDC), for each parameter.

Design

Two repeated measurements of cardiopulmonary exercise outcomes were obtained, with a median time interval of 16 days.

Methods

Thirty-two PwMS suffering from subjective fatigue performed cardiopulmonary exercise tests on a cycle ergometer, to voluntary exhaustion. We calculated the reliability, in terms of the intra-class correlation coefficient (ICC [2,k]; absolute agreement), and the measurement error, in terms of standard error of measurement (SEM) and SDC at individual (SDC_individual) and group level (SDC_group).

Results

The ICC for VO₂peak was 0.951, with an SEM of 0.131 L∙min⁻¹ and an SDC_individual of 0.364 L∙min⁻¹. When corrected for bodyweight, the ICC of VO₂peak was 0.933, with an SEM of 1.7 mL∙kg⁻¹∙min⁻¹ and in an SDC_individual of 4.6 mL∙kg⁻¹∙min⁻¹.

Limitations

Generalization of our study results is restricted to fatigued PwMS with a low to mild level of disability.

Conclusions

At individual level, cardiopulmonary exercise testing can be used reliably to assess physical fitness in terms of VO₂peak, but less so to determine significant changes. At group level, VO₂peak can be reliably used to determine physical fitness status and establish change over time.     

Peak power and pulmonary oxygen uptake during knee extension exercise – comparisons among different incremental protocols

Four incremental protocols of knee extension exercise of different stage durations were compared to study the effect of the protocol upon power output at the last stage (P _peak). Previous studies of knee extension have found very different power outputs with similar ergometers and these large differences have been interpreted as being the result of the fatigue due to the durations of the protocols. The knee extension device used in previous studies was modified to avoid the action of the knee and hip flexors: the subjects pushing on a lever instead of pulling a rod. In the present study five subjects performed four incremental knee extension exercises which differed with regard to stage duration (60, 90, 180 or 360 s) on this ergometer. The P _peak, peak oxygen uptake (V˙O_2peak) and peak heart rate (HR_peak) were measured at the end of each of these four incremental protocols. In eight subjects, the reliability of the protocols with the two shortest increments (60 and 90-s stages) was verified by measuring P _peak at 60 s and 90 s (P _peak60, P _peak90) twice. The knee ergometer proposed in the present paper was easy to use without any special training and should improve the measurement of P _peak. The P _peak60 [49.4 (SD 5.6) W] was higher than at 180 s [P _peak180, 43.6 (SD 5.8) W, P < 0.05] and at 360 s [P _peak360, 43.4 (SD 5.3) W, P < 0.05]. All the other differences in P _peak, V˙O_{2 peak} and HR_peak were not significant. All correlations between P _peak60, P _peak90, P _peak180 and P _peak360 were significant, except those between P _peak360 and P _peak90 or P _peak180. The effect of the stage duration on power output and oxygen uptake at the end of the knee extension exercises was not great. Consequently, the large differences in power output and oxygen uptake observed in previous studies cannot be explained by the protocol only. The significant difference between P _{peak 60} and P _peak90 was of the order of 10% in agreement with findings in the literature using cycle ergometry. The reliability of P _peak60 and P _peak90 was high and the use of these protocols can be recommended if further studies show that the measurement of P _peak, is useful in the evaluation of local endurance. Accepted: 2 April 1998     

Alternatives to the Six-Minute Walk Test in Pulmonary Arterial Hypertension

Introduction

The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH. We tested the hypothesis that endurance tests induce a near-maximal physiological demand comparable to incremental tests. We also hypothesized that differences in respiratory response during exercise would be related to the characteristics of the exercise tests.

Methods

Within two weeks, twenty-one PAH patients (mean age: 54(15) years; mean pulmonary arterial pressure: 42(12) mmHg) completed two cycling exercise tests (incremental cardiopulmonary cycling exercise test (CPET) and CET) and three field tests (ISWT, ESWT and six-minute walk test (6MWT)). Physiological parameters were continuously monitored using the same portable telemetric device.

Results

Peak oxygen consumption (VO_2peak) was similar amongst the five exercise tests (p = 0.90 by ANOVA). Walking distance correlated markedly with the VO_2peak reached during field tests, especially when weight was taken into account. At 100% exercise, most physiological parameters were similar between incremental and endurance tests. However, the trends overtime differed. In the incremental tests, slopes for these parameters rose steadily over the entire duration of the tests, whereas in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise at which point they appeared far less steep until test end. Moreover, cycling exercise tests induced higher respiratory exchange ratio, ventilatory demand and enhanced leg fatigue measured subjectively and objectively.

Conclusion

Endurance tests induce a maximal physiological demand in PAH. Differences in peak respiratory response during exercise are related to the modality (cycling vs. walking) rather than the progression (endurance vs. incremental) of the exercise tests.     

The Andersen Aerobic Fitness Test: Reliability and Validity in 10-Year-Old Children

Background

High aerobic fitness is consistently associated with a favorable metabolic risk profile in children. Direct measurement of peak oxygen consumption (VO_2peak) is often not feasible, thus indirect tests such as the Andersen test are required in many settings. The present study seeks to determine the reliability and validity of the Andersen test in 10-year-old children.

Methods

A total of 118 10-year-old children (67 boys and 51 girls) were recruited from one school and performed four VO_2peak tests over three weeks: three Andersen tests (indirect) and one continuous progressive treadmill test (direct). Of these, 104 children provided valid data on all Andersen tests and 103 children also provided valid data on the direct treadmill test. Reliability and validity were assessed using Bland Altman plots and linear regression analysis.

Results

Bias (mean change) and random error (limits of agreement) were 26.7±125.2 m for test 2 vs. test 1 (p<.001 for mean difference) and 3.9±88.8 m for test 3 vs. test 2 (p = .514 for mean difference). The equation to estimate VO_2peak suggested by Andersen et al. (2008) showed a poor fit in the present sample; thus, we suggest a new equation: VO_2peak = 23.262+0.050*Andersen distance –3.858*gender –0.376*body weight (R² = 0.61, standard error of the estimate = 5.69, p<.001, boys = 0, girls = 1).

Conclusions

The Andersen test provided reliable and valid data on a group level. However, a substantial degree of individual variability was found for estimates of VO_2peak. Researchers should be aware of the amount of noise in indirect tests that estimate aerobic fitness.     

Effects of 28 days of beta-alanine and creatine monohydrate supplementation on aerobic power,ventilatory and lactate thresholds,and time to exhaustion

Summary. The effect of beta-alanine (β-Ala) alone or in combination with creatine monohydrate (Cr) on aerobic exercise performance is unknown. The purpose of this study was to examine the effects of 4 weeks of β-Ala and Cr supplementation on indices of endurance performance. Fifty-five men (24.5 ± 5.3 yrs) participated in a double-blind, placebo-controlled study and randomly assigned to one of 4 groups; placebo (PL, n = 13), creatine (Cr, n = 12), beta-alanine (β-Ala, n = 14), or beta-alanine plus creatine (CrBA, n = 16). Prior to and following supplementation, participants performed a graded exercise test on a cycle ergometer to determine VO_2peak, time to exhaustion (TTE), and power output, VO₂, and percent VO_2peak associated with VT and LT. No significant group effects were found. However, within groups, a significant time effect was observed for CrBa on 5 of the 8 parameters measured. These data suggest that CrBA may potentially enhance endurance performance.     

Physiological correlates of endurance time variability during constant-workrate cycling exercise in patients with COPD

Rationale

The endurance time (T_end) during constant-workrate cycling exercise (CET) is highly variable in COPD. We investigated pulmonary and physiological variables that may contribute to these variations in T_end.

Methods

Ninety-two patients with COPD completed a CET performed at 80% of peak workrate capacity (W_peak). Patients were divided into tertiles of T_end [Group 1: <4 min; Group 2: 4–6 min; Group 3: >6 min]. Disease severity (FEV₁), aerobic fitness (W_peak, peak oxygen consumption [ _peak], ventilatory threshold [ _VT]), quadriceps strength (MVC), symptom scores at the end of CET and exercise intensity during CET (heart rate at the end of CET to heart rate at peak incremental exercise ratio [HR_CET/HR_peak]) were analyzed as potential variables influencing T_end.

Results

W_peak, _peak, _VT, MVC, leg fatigue at end of CET, and HR_CET/HR_peak were lower in group 1 than in group 2 or 3 (p≤0.05). _VT and leg fatigue at end of CET independently predicted T_end in multiple regression analysis (r = 0.50, p = 0.001).

Conclusion

T_end was independently related to the aerobic fitness and to tolerance to leg fatigue at the end of exercise. A large fraction of the variability in T_end was not explained by the physiological parameters assessed in the present study. Individualization of exercise intensity during CET should help in reducing variations in T_end among patients with COPD.     

Short-Term Intensified Cycle Training Alters Acute and Chronic Responses of PGC1α and Cytochrome C Oxidase IV to Exercise in Human Skeletal Muscle

Reduced activation of exercise responsive signalling pathways have been reported in response to acute exercise after training; however little is known about the adaptive responses of the mitochondria. Accordingly, we investigated changes in mitochondrial gene expression and protein abundance in response to the same acute exercise before and after 10-d of intensive cycle training. Nine untrained, healthy participants (mean±SD; VO_2peak 44.1±17.6 ml/kg/min) performed a 60 min bout of cycling exercise at 164±18 W (72% of pre-training VO_2peak). Muscle biopsies were obtained from the vastus lateralis muscle at rest, immediately and 3 h after exercise. The participants then underwent 10-d of cycle training which included four high-intensity interval training sessions (6×5 min; 90–100% VO_2peak) and six prolonged moderate-intensity sessions (45–90 min; 75% VO_2peak). Participants repeated the pre-training exercise trial at the same absolute work load (64% of pre-training VO_2peak). Muscle PGC1-α mRNA expression was attenuated as it increased by 11- and 4- fold (P<0.001) after exercise pre- and post-training, respectively. PGC1-α protein expression increased 1.5 fold (P<0.05) in response to exercise pre-training with no further increases after the post-training exercise bout. RIP140 protein abundance was responsive to acute exercise only (P<0.01). COXIV mRNA (1.6 fold; P<0.01) and COXIV protein expression (1.5 fold; P<0.05) were increased by training but COXIV protein expression was decreased (20%; P<0.01) by acute exercise pre- and post-training. These findings demonstrate that short-term intensified training promotes increased mitochondrial gene expression and protein abundance. Furthermore, acute indicators of exercise-induced mitochondrial adaptation appear to be blunted in response to exercise at the same absolute intensity following short-term training.     

Peak exercise capacity estimated from incremental shuttle walking test in patients with COPD: a methodological study

Background

In patients with COPD, both laboratory exercise tests and field walking tests are used to assess physical performance. In laboratory tests, peak exercise capacity in watts (W peak) and/or peak oxygen uptake (VO₂ peak) are assessed, whereas the performance on walking tests usually is expressed as distance walked. The aim of the study was to investigate the relationship between an incremental shuttle walking test (ISWT) and two laboratory cycle tests in order to assess whether W peak could be estimated from an ISWT.

Methods

Ninety-three patients with moderate or severe COPD performed an ISWT, an incremental cycle test (ICT) to measure W peak and a semi-steady-state cycle test with breath-by-breath gas exchange analysis (CPET) to measure VO₂ peak. Routine equations for conversion between cycle tests were used to estimate W peak from measured VO₂ peak (CPET). Conversion equation for estimation of W peak from ISWT was found by univariate regression.

Results

There was a significant correlation between W peak and distance walked on ISWT × body weight (r = 0.88, p < 0.0001). The agreement between W peak measured by ICT and estimated from ISWT was similar to the agreement between measured W peak (ICT) and W peak estimated from measured VO₂ peak by CPET.

Conclusion

Peak exercise capacity measured by an incremental cycle test could be estimated from an ISWT with similar accuracy as when estimated from peak oxygen uptake in patients with COPD.

     

Optimizing the exercise protocol for cardiopulmonary assessment

Twelve normal men performed 1-min incremental exercise tests to exhaustion in approximately 10 min on both treadmill and cycle ergometer. The maximal O2 uptake (VO2 max) and anaerobic threshold (AT) were higher (6 and 13%, respectively) on the treadmill than the cycle; the AT was reached at about 50% of VO2 max on both ergometers. Maximal CO2 output, heart rate, and O2 pulse were also slightly, but significantly higher on the treadmill. Maximal ventilation, gas exchange ratio, and ventilatory equivalents for O2 and CO2 for both forms of exercise were not significantly different. To determine the optimum exercise test for both treadmill and cycle, we exercised five of the subjects at various work rate increments on both ergometers in a randomized design. The treadmill increments were 0.8, 1.7, 2.5, and 4.2%/min at a constant speed of 3.4 mph, and 1.7 and 4.2%/min at 4.5 mph. Cycle increments were 15, 30, and 60 W/min. The VO2 max was significantly higher on tests where the increment magnitude was large enough to induce test durations of 8-17 min, but the AT was independent of test duration. Thus, for evaluating cardiopulmonary function with incremental exercise testing by either treadmill or cycle, we suggest selecting a work rate increment to bring the subject to the limit of his tolerance in about 10 min.     

Walking performance and economy in chronic heart failure patients pre and post exercise training

The effect of a 3-week exercise programme on performance and economy of walking was analysed in 16 male patients with chronic heart failure [mean age 51.8 (SD 6.9) years, height 174.9 (SD 6.3) cm, body mass 75.3 (SD 11.5) kg, ejection fraction 20.8 (SD 5.0)%]. They were submitted to a cardiopulmonary exercise test on a cycle ergometer and a 6-min walking test on a treadmill before and after the period of exercise training. The training programme consisted of interval cycle (five times a week for 15 min), and treadmill ergometer training (three times a week for 10 min) at approximately 70% cycling peak oxygen uptake (O_2peak) and supplementary exercises (three times a week for 20 min). Compared to the pre values cycling O_2peak [11.9 (SD 2.9) vs 14.0 (SD 2.3) ml ·  kg^–1 · min^–1], maximal self paced walking speed [0.68 (SD 0.33) vs 1.16 (SD 0.30) m · s^–1], and net walking power [2.16 (SD 0.89) vs 2.73 (SD 0.91) W · kg^–1] had increased (P < 0.01) while net energy cost [3.31 (SD 0.66) vs 2.33 (SD 0.38) J · kg^–1 ·  m^–1] had decreased (P < 0.001) after the training period. Approximately 42% of the increase of walking speed resulted from a higher walking power output, whereas approximately 58% corresponded to a positive effect on walking economy. The improvement in walking economy was a function of an increase in walking velocity itself and a result of a more efficient walking technique. These results would indicate that in patients with marked exercise intolerance, adequate exercise training programmes could contribute to favourable metabolic changes with positive effects on the economy of motion. Accepted: 29 August 1996     

Maximal aerobic capacity for repetitive lifting: comparison with three standard exercise testing modes

A multi-stage, repetitive lifting maximal oxygen uptake (VO2max) test was developed to be used as an occupational research tool which would parallel standard ergometric VO2max testing procedures. The repetitive lifting VO2max test was administered to 18 men using an automatic repetitive lifting device. An intraclass reliability coefficient of 0.91 was obtained with data from repeated tests on seven subjects. Repetitive lifting VO2max test responses were compared to those for treadmill, cycle ergometer and arm crank ergometer. The mean +/- SD repetitive lifting VO2max of 3.20 +/- 0.42 l.min-1 was significantly (p less than 0.01) less than treadmill VO2max (delta = 0.92 l.min-1) and cycle ergometer VO2max (delta = 0.43 l.min-1) and significantly greater than arm crank ergometer VO2max (delta = 0.63 l.min-1). The correlation between repetitive lifting oxygen uptake and power output was r = 0.65. VO2max correlated highly among exercise modes, but maximum power output did not. The efficiency of repetitive lifting exercise was significantly greater than that for arm cranking and less than that for leg cycling. The repetitive lifting VO2max test has an important advantage over treadmill or cycle ergometer tests in the determination of relative repetitive lifting intensities. The individual curves of VO2 vs. power output established during the multi-stage lifting VO2max test can be used to accurately select work loads required to elicit given percentages of maximal oxygen uptake.     

Acute physiological and perceptual responses to moderate intensity cycling with different levels of blood flow restriction

The aim of this study was to compare: i) the physiological and perceptual responses of low-load exercise [(moderate intensity exercise (MI)] with different levels of blood flow restriction (BFR), and ii) MI with BFR on the bike with high intensity (HI) exercise without BFR. The protocol involved large muscle mass exercise at different levels of BFR, and this differentiates our study from others. Twenty-one moderately trained males (age: 24.6 ± 2.4 years; VO_2peak: 47.2 ± 7.0 ml^.kg^-1.min^-1, mean ± sd) performed one maximal graded exercise test and seven 5-min constant-load cycling bouts. Six bouts were at MI [40% _peak power (P_peak), 60%VO_2peak], one without BFR and five with different levels of BFR (40%, 50%, 60%, 70%, 80% of estimated arterial occlusion pressure). The HI bout (70%P_peak, 90%VO_2peak) was without BFR. Oxygen uptake (VO₂), heart rate (HR), blood lactate (BLa), rate of perceived exertion (RPE), and tissue oxygen saturation (TSI) were recorded. Regardless of pressure, HR, BLa and RPE during MI-BFR were higher compared to MI (p < 0.05, ES: moderate to very large), and TSI reduction was greater in MI-BFR than MI (p < 0.05, ES: moderate to large). The responses of VO₂, HR, BLa, RPE and TSI induced by the different levels of BFR in MI-BFR were similar. Regardless of pressure, the responses of VO₂, HR, BLa and RPE induced by MI-BFR were lower than HI (p < 0.05), except for TSI. TSI change was similar between MI-BFR and HI. It appears that BFR equal to 40% of arterial occlusion pressure is sufficient to reduce TSI when exercising with a large muscle mass.     

Quantification of the energy expenditure during training exercises in Standardbred trotters

An appropriate energy feeding management that ensures the optimal dietary energy supply according to the energy expenditure (EE) is a crucial component for the horse’s performance. The main purpose of this study was to determine the EE during four specific exercises used in the training of Standardbred trotters (promenade, jogging, parcours and interval work-outs). A total of six Standardbred geldings performed four different testing situations on a track. The intensity (expressed in percentage of the maximal velocity over 500 m, i.e. v500) and volume (distance and duration) of the testing situations were determined according to practices reported by French trainers. Promenade and jogging included only an exercise phase, whereas parcours and interval situations also included a warm-up and a recovery phase. Oxygen uptake (VO₂), carbon dioxide production (VCO₂) and heart rate (HR) were continuously recorded from 2 min before the beginning through to the end of the testing situations, using a portable respiratory gas analyser. Blood lactate levels and rectal temperature were determined before and immediately after the exercise phase of each testing situations. EE of the different phases (warm-up, exercise and recovery) and EE of the entire testing situations (EE_TOTAL) were calculated from VO₂ measurements and the O₂ caloric equivalent. Interval and parcours situations induced higher physiological responses than promenade and jogging situations, particularly in terms of VO_2peak, VCO_2peak and HR_peak. The highest blood lactate concentration (6 mmol/l) was measured after the interval exercise, and respiratory exchange ratios ⩾1 were observed only for the parcours situation. The EE of exercise phase varied from 0.49 to 1.79 kJ/min per kg for promenade and parcours situations. The EE of warm-up and recovery phases did not differ between parcours and interval situations, and was estimated at 1.04 and 0.57 kJ/min per kg BW, respectively. On average, the warm-up and the recovery phases contributed to 38% and 19% of the EE_TOTAL. For promenade, jogging, parcours and interval situations, EE_TOTAL was evaluated at 12 618, 11 119, 13 698 and 18 119 kJ, respectively.     

Aerobic Fitness in Children and Young Adults with Primary Ciliary Dyskinesia

Background

Although aerobic fitness is regarded as an overall prognostic measure of morbidity and mortality, its evaluation in the chronic progressive sinopulmonary disease primary ciliary dyskinesia (PCD) has been infrequently and inconsistently reported. Here we assessed peak oxygen uptake (VO_2peak) in a large well-characterized cohort of PCD patients, and explored whether VO_2peak was associated with parameters of pulmonary function, self-reported physical limitations, and physical activity level.

Methods

VO_2peak, spirometry, diffusing capacity, whole-body plethysmography, and nitrogen multiple breath inert gas washout (N₂ MBW) were assessed in a cross-sectional, single-occasion study of clinically stable children and young adults with PCD. We used a questionnaire including self-reported physical limitations in everyday life or in vigorous activities, and estimation of weekly hours of strenuous physical activity. VO_2peak in PCD patients was compared with that in matched, healthy control subjects and a national reference.

Results

Forty-four PCD patients aged 6–29 years exhibited reduced VO_2peak compared to healthy controls (P<0.001) and the national reference. VO_2peak was abnormal (z-score <–1.96) in 34% of PCD patients. Spirometric values, RV/TLC, and indices of N₂ MBW were significantly abnormal, but VO_2peak only correlated with FEV₁ and DL_CO/V_A. VO_2peak correlated with complaints of moderate or significant limitations in vigorous activities (P = 0.0001), exhibited by 39% of PCD patients.

Conclusion

One-third of PCD patients exhibited substantially lower aerobic fitness than healthy subjects. Aerobic fitness correlated with FEV₁, DL_CO/V_A and self-reported complaints of limitations in vigorous physical activity. These findings are most likely explained by PCD pulmonary disease and its impact on pulmonary function and physical ability. Considering fitness as an important outcome and including regular strenuous physical activity in PCD treatment would probably altogether increase pulmonary clearance, lung function, aerobic fitness, and quality of life, and prevent lifestyle-related diseases.     

Prediction of Cardiorespiratory Fitness by the Six-Minute Step Test and Its Association with Muscle Strength and Power in Sedentary Obese and Lean Young Women: A Cross-Sectional Study

Impaired cardiorespiratory fitness (CRF) is a hallmark characteristic in obese and lean sedentary young women. Peak oxygen consumption (VO_2peak) prediction from the six-minute step test (6MST) has not been established for sedentary females. It is recognized that lower-limb muscle strength and power play a key role during functional activities. The aim of this study was to investigate cardiorespiratory responses during the 6MST and CPX and to develop a predictive equation to estimate VO_2peak in both lean and obese subjects. Additionally we aim to investigate how muscle function impacts functional performance. Lean (LN = 13) and obese (OB = 18) women, aged 20–45, underwent a CPX, two 6MSTs, and isokinetic and isometric knee extensor strength and power evaluations. Regression analysis assessed the ability to predict VO_2peak from the 6MST, age and body mass index (BMI). CPX and 6MST main outcomes were compared between LN and OB and correlated with strength and power variables. CRF, functional capacity, and muscle strength and power were lower in the OB compared to LN (<0.05). During the 6MST, LN and OB reached ~90% of predicted maximal heart rate and ~80% of the VO_2peak obtained during CPX. BMI, age and number of step cycles (NSC) explained 83% of the total variance in VO_2peak. Moderate to strong correlations between VO_2peak at CPX and VO_2peak at 6MST (r = 0.86), VO_2peak at CPX and NSC (r = 0.80), as well as between VO_2peak, NSC and muscle strength and power variables were found (p<0.05). These findings indicate the 6MST, BMI and age accurately predict VO_2peak in both lean and obese young sedentary women. Muscle strength and power were related to measures of aerobic and functional performance.     

End Criteria for Reaching Maximal Oxygen Uptake Must Be Strict and Adjusted to Sex and Age: A Cross-Sectional Study

Objective

To describe different end criteria for reaching maximal oxygen uptake (VO_2max) during a continuous graded exercise test on the treadmill, and to explore the manner by which different end criteria have an impact on the magnitude of the VO_2max result.

Methods

A sample of 861 individuals (390 women) aged 20–85 years performed an exercise test on a treadmill until exhaustion. Gas exchange, heart rate, blood lactate concentration and Borg Scale_6–20 rating were measured, and the impact of different end criteria on VO_2max was studied;VO₂ leveling off, maximal heart rate (HR_max), different levels of respiratory exchange ratio (RER), and postexercise blood lactate concentration.

Results

Eight hundred and four healthy participants (93%) fulfilled the exercise test until voluntary exhaustion. There were no sex-related differences in HR_max, RER, or Borg Scale rating, whereas blood lactate concentration was 18% lower in women (P<0.001). Forty-two percent of the participants achieved a plateau in VO₂; these individuals had 5% higher ventilation (P = 0.033), 4% higher RER (P<0.001), and 5% higher blood lactate concentration (P = 0.047) compared with participants who did not reach a VO₂ plateau. When using RER ≥1.15 or blood lactate concentration ≥8.0 mmol•L^–1, VO_2max was 4% (P = 0.012) and 10% greater (P<0.001), respectively. A blood lactate concentration ≥8.0 mmol•L^–1 excluded 63% of the participants in the 50–85-year-old cohort.

Conclusions

A range of typical end criteria are presented in a random sample of subjects aged 20–85 years. The choice of end criteria will have an impact on the number of the participants as well as the VO_2max outcome. Suggestions for new recommendations are given.     

Pre-radiotherapy daily exercise training in non-small cell lung cancer: A feasibility study

AimTo examine the feasibility of an individual, supervised, structured moderate-to-high intensity cycle ergometer exercise training immediately before radiotherapy in patients undergoing concomitant chemoradiotherapy for locally advanced non-small cell lung cancer (NSCLC).BackgroundLung cancer is the most common form of cancer. Despite significant advancements in therapy and supportive care it is still the leading cause of cancer-related death worldwide.Materials and methodsRandomized controlled study design; patients with NSCLC receiving concomitant chemoradiotherapy were recruited and randomly assigned to either the exercise (EXE) or the control (CON) group. Exercise training consisted of 20 min moderate-to-high intensity aerobic interval training 5 times per week (Mon–Fri) prior to radiotherapy. Secondary outcomes were assessed at baseline and after 7 weeks: peak oxygen consumption (VO_2peak), functional capacity (6MWD), pulmonary function (FEV1), psychosocial parameters (quality of life (FACT-L), anxiety and depression (HADS)) and cancer-related side effects (reported daily).ResultsFifteen patients were included. All patients completed a baseline test, while 13 patients were eligible for a posttest. The recruiting rate was 44.1% and the overall attendance rate to exercise was 90.0% with an adherence rate to full exercise participation of 88.1%. No adverse events or any unexpected reactions were observed during the exercise sessions. No significant differences were observed within or between groups from baseline to post intervention in any of the secondary outcomes.ConclusionThis study demonstrated ‘proof of principle’ that daily moderate-to-high intensity cycle ergometer exercise was feasible, safe and well tolerated among newly diagnosed patients with locally advanced NSCLC undergoing concomitant chemoradiotherapy. Larger randomized controlled trials are warranted.     

Reduction of Arterial Stiffness by Exercise Training Is Associated with Increasing Plasma Apelin Level in Middle-Aged and Older Adults

Aging-induced deterioration of arterial stiffness is decreased by regular exercise, and increased nitric oxide (NO) production participates in this effect. Apelin regulates endothelial NO synthase in endothelial cells, promoting NO production. However, the effect of aerobic exercise training on circulating apelin levels in healthy middle-aged and older adults remains unknown. Accordingly, this study aimed to clarify the effects of regular aerobic exercise on apelin concentrations in middle-aged and older adults. Thirty-four healthy middle-aged and older subjects (67.0 ± 1.3 years) were randomly divided into two groups: exercise intervention and sedentary controls. Subjects in the training group completed 8-week of aerobic exercise training (60–70% peak oxygen uptake [VO_2peak] for 45 min, 3 days/week). Before and after the intervention, we evaluated plasma apelin and nitrite/nitrate (NOx) concentrations, VO_2peak, and arterial stiffness index. In the training group, VO_2peak was significantly increased, and carotid β-stiffness was significantly decreased, after the intervention (P<0.05). Moreover, plasma apelin and NOx levels were significantly increased in the training group after the intervention (P<0.05). Additionally, there was a correlation between the training effects of plasma apelin levels and carotidβ-stiffness (r = −0.508, P = 0.032) and plasma NOx levels (r = 0.494, P = 0.037). By contrast, none of these parameters changed significantly in the control group. These results suggest that the increased in plasma apelin levels may be associated with exercise training-induced alternation of arterial stiffness in middle-aged and older adults.