Efficacy of constant load verification testing to confirm VO2max attainment

Although maximal oxygen uptake (VO₂max) has been measured for almost 100 years, it is unknown when ‘true’ VO₂max is attained. Primary (the VO₂ plateau) and secondary criteria are used to confirm VO₂max incidence, but frequency of the VO₂ plateau varies, and secondary criteria are relatively invalid. The verification test (VER) seems to elicit similar estimates of VO₂max versus the incremental value (INC), yet existing data are limited by small populations and use of inadequate criteria to confirm ‘true’ VO₂max. We investigated the efficacy of VER by analysing data from 109 participants who underwent INC followed by VER at 105% or 110% of peak power output (PPO). Differences in VO₂max between VER and INC were analysed, and intraclass correlation coefficient (ICC), standard error of the mean (SEM) and minimum difference (MD) were computed. Results showed that VO₂max was significantly higher (2%, P<0·05) in INC versus VER, VO₂max was highly related between protocols (ICC = 0·99) and SEM and MD were low. However, 11% of participants did not reveal ‘true’ VO₂max as the verification value was higher than INC by 3·0% ‐ 3·3%. Fitness level altered the difference in VO₂max between INC and VER in study one, as lower fitness individuals showed a larger difference in VO₂max between protocols, although gender did not affect the difference in VO₂max between protocols. Our data show that VER does not verify ‘true’ VO₂max in all individuals, which may be related to their fitness level.     

Alterations in VO2max and the VO2 plateau with manipulation of sampling interval

Background: The most accepted criterion for confirming attainment of VO₂max is a plateau in oxygen consumption (VO₂) at VO₂max, but its incidence varies. Aims: To compare VO₂max and VO₂ plateau incidence across various sampling intervals, and to examine predictors of the change in VO₂ (ΔVO₂) at VO₂max. Methods: Sedentary, recreationally‐active, and endurance‐trained subjects (n = 108, age = 24·2 ± 6·2 year) completed incremental exercise on the treadmill or cycle ergometer. Gas exchange data were obtained breath‐by‐breath and time‐averaged every 15, 30, and 60 s. VO₂max attainment was verified with the Taylor et al. (1955) criterion (ΔVO₂ at VO₂max ≤2·1 ml kg^?1 min^?1). Multiple regression was used to examine predictors of ΔVO₂ at VO₂max. Results: VO₂ plateau incidence was higher using breath‐by‐breath (81%) and 15 (91%) and 30 s time averaging (89%) versus 60 s averaging (59%). Compared to 60 s averaging, VO₂max was significantly higher (P<0·05) when data were obtained breath‐by‐breath and with 15 and 30 s time‐averaging compared to 60 s sampling. VO₂max was not related to VO₂ plateau incidence. Respiratory rate was a significant predictor of ΔVO₂ at VO₂max in endurance‐trained subjects. Conclusion: More frequent data acquisition revealed higher VO₂max and incidence of the VO₂ plateau compared to 60 s time averaging. Secondary criteria to verify VO₂max attainment should not be used, as they do not discern between subjects who do and do not reveal a plateau in VO₂ at VO₂max.     

The influence of a fast ramp rate on peak cardiopulmonary parameters during arm crank ergometry

The influence of a very fast ramp rate on cardiopulmonary variables at ventilatory threshold and peak exercise during a maximal arm crank exercise test has not been extensively studied. Considering that short arm crank tests could be sufficient to achieve maximal oxygen consumption (VO₂), it would be of practical interest to explore this possibility. Thus, this study aimed to analyse the influence of a fast ramp rate (20 W min^?1) on the cardiopulmonary responses of healthy individuals during a maximal arm crank ergometry test. Seventeen healthy individuals performed maximal cardiopulmonary exercise tests (Ultima CardiO2; Medical Graphics Corporation, St Louis, USA) in arm ergometer (Angio, LODE, Groningen, The Netherlands) following two protocols in random order: fast protocol (increment: 2 w/6 s) and slow protocol (increment: 1 w/6 s). The fast protocol was repeated 60–90 days after the 1st test to evaluate protocol reproducibility. Both protocols elicited the same peak VO₂ (fast: 23·51 ± 6·00 versus slow: 23·28 ± 7·77 ml kg^?1 min^?1; P = 0·12) but peak power load in the fast ramp protocol was higher than the one in the slow ramp protocol (119 ± 43 versus. 102 ± 39 W, P < 0·001). There was no other difference in ventilatory threshold and peak exercise variables when 1st and 2nd fast protocols were compared. Fast protocol seems to be useful when healthy young individuals perform arm cardiopulmonary exercise test. The usefulness of this protocol in other populations remains to be evaluated.     

A call to action towards an evidence‐based approach to using verbal encouragement during maximal exercise testing

By definition, maximal exercise testing inherently requires participants to give a maximal effort. This is an important practical issue as submaximal efforts can produce invalid test results. Verbal encouragement is commonly used to motivate participants to maintain or increase effort investment during maximal exercise testing. Accordingly, studies have reported significant increases in time to exhaustion of between 8% and 18% during VO_2max and multistage shuttle run tests, and a significant 30·5 m mean increase in 6‐min walk test distance. Significant improvements during shorter tests, such as the Wingate and 2‐min walk tests, have not been observed however. Although participants typically perceive verbal encouragement positively during maximal exercise testing, around one‐third have neutral or negative perceptions. Despite the ubiquity and importance of verbal encouragement during maximal exercise testing, surprisingly little research has investigated the characteristics of effective encouragement with respect to its content, timing and frequency. The only randomized controlled trial to investigate one of these issues observed that verbal encouragement delivered every 20 s increased time to exhaustion during VO_{2 max} testing, but not every 60 or 180 s. Of particular concern is that several exercise testing guidelines have incorporated specific guidelines for the use of verbal encouragement, but not provided any theoretical or empirical justification, presumably because of the limited research to inform practice. Recent empirical research does provide some important insight into participant preference for the content and timing of verbal encouragement during maximal exercise testing; however, much more research is clearly required to establish comprehensive evidence‐based guidelines.     

Assessment of exercise capacity in women with type 2 diabetes

The primary aim of this study was to compare the maximal oxygen uptake as evaluated from a submaximal exercise test (EVO2peak) to direct measurements of VO2peak during a maximal exercise test as means of monitoring the aerobic endurance capacity in women with type 2 diabetes (T2D). Twenty-seven women with T2D participated in the study. The program consisted of combined group training 1 h twice a week during 12 weeks and walks 1 h per week. EVO2 max was estimated using a submaximal exercise test on a bicycle ergometer ad modum Astrand. VO2peak and maximal work rate were measured using an incremental maximal exercise test on an electrically braked bicycle ergometer at baseline and after 6 and 12 weeks. EVO2peak was higher than VO2peak at baseline and significantly higher at 12 weeks (EVO2peak1.92+/-0.54 l min(-1), VO2peak 1.41+/-0.36, P<0.005). Maximal work rate increased significantly after 12 weeks (12+/-15, P<0.005) compared to baseline. The main finding of this study was that EVO2peak assessed using a submaximal exercise test, systematically overestimated VO2peak. The combined group training increased maximal work rate but not VO2peak. This is likely to reflect peripheral adaptation to exercise and/or improved mechanical efficiency.     

A comparison of head motion and prefrontal haemodynamics during upright and recumbent cycling exercise

The aim of this observational study was to compare head motion and prefrontal haemodynamics during exercise using three commercial cycling ergometers. Participants (n = 12) completed an incremental exercise test to exhaustion during upright, recumbent and semi‐recumbent cycling. Head motion (using accelerometry), physiological data (oxygen uptake, end‐tidal carbon dioxide [P_ETCO₂] and heart rate) and changes in prefrontal haemodynamics (oxygenation, deoxygenation and blood volume using near infrared spectroscopy [NIRS]) were recorded. Despite no difference in oxygen uptake and heart rate, head motion was higher and P_ETCO₂ was lower during upright cycling at maximal exercise (P<0·05). Analyses of covariance (covariates: head motion P>0·05; P_ETCO₂, P<0·01) revealed that prefrontal oxygenation was higher during semi‐recumbent than recumbent cycling and deoxygenation and blood volume were higher during upright than recumbent and semi‐recumbent cycling (respectively; P<0·05). This work highlights the robustness of the utility of NIRS to head motion and describes the potential postural effects upon the prefrontal haemodynamic response during upright and recumbent cycling exercise.     

不同损伤平面脊髓损伤患者运动试验中心肺功能的变化

目的探讨不同损伤平面脊髓损伤患者运动试验中心肺功能的变化。方法将15例脊髓损伤患者分为高位截瘫组(8例)和低位截瘫组(7例),均在轮椅跑台上进行极量递增负荷运动试验,测量心肺功能指标。结果低位截瘫患者的心肺功能优于高位截瘫(P<0.05~0.01)。结论脊髓损伤平面越高,心肺功能越低,即损伤平面与心肺功能成反比。     

Blood metabolite data in response to maximal exercise in healthy subjects

Maximal exercise test with gas exchange measurement evaluates exercise capacities with maximal oxygen uptake (VO(2) max) measurement. Measurements of lactate (L), lactate/pyruvate ratio (L/P) and ammonium (A) during rest, exercise and recovery enhance interpretative power of maximal exercise by incorporating muscular metabolism exploration. Maximal exercise test with gas exchange measurement is standardized in cardiopulmonary evaluations but, no reference data of blood muscular metabolites are available to evaluate the muscular metabolism. We determined normal values of L, L/P and A during a standardized maximal exercise and recovery in 48 healthy sedentary volunteers and compared with results obtained in four patients with exercise intolerance and a mitochondrial disease. In healthy subjects, L, L/P and A rose during exercise. In 98% of them L, L/P or A decreased between the fifth and the fifteenth minutes of recovery. In mitochondrial patients, VO(2) max was normal or low, and L, L/P and A had the same evolution as normal subjects or showed no decrease during recovery. We gave normal L, L/P and A values, which establish references for a maximal exercise test with muscular metabolism exploration. This test is helpful for clinicians in functional evaluation, management and treatment of metabolic myopathy and would be a useful tool in diagnosis of metabolic myopathy.     

The incidence of plateau at VO(2max) is affected by a bout of prior-priming exercise

The purpose of this study was to determine the effect of 6 min of prior-priming exercise on the incidence of plateau at VO(2max). Twelve trained cyclists (age, 21 ± 3 years; height, 175·0 ± 8·0 cm; weight, 69·0 ± 10·4 kg; maximal oxygen uptake (VO(2max)), 56·3 ± 6·9 ml kg(-1) min(-1)) completed three incremental tests to volitional exhaustion, which were classified as unprimed (UP), heavy-primed (HP) and severe-primed (SP), at a work rate of 1 W 2 s(-1), from an initial workload of 100 W, for the determination of VO(2max). VO(2max) trial in the HP and SP conditions was preceded by a period of 4-min unloaded cycling followed by a further 6 min of constant load cycling at Δ50% VO(2) gas exchange threshold (GET)-VO(2max) (HP) and Δ75% VO(2) GET-VO(2max) (SP). Expired air was recorded on a breath-by-breath basis during all trials. The criteria adopted for a plateau in VO(2max) was a ΔVO(2) over the final two consecutive 30-s sampling periods ≤ 2·1 ml kg(-1) min(-1). There was a significant increase in plateau responses between the UP (50%) and HP (100%) conditions (P = 0·001) coupled with a significant change in the slope of the regression line during the final 60 s of the VO(2max) test, UP and HP (P = 0·0299) and UP and SP (P = 0·0296). These data suggest that a bout of prior-priming exercise promotes an increased incidence of plateau responses at VO(2max) . It is suggested that future studies address how such an approach can be adopted without prior knowledge of GET.     

Effects of surgical masks on the responses to constant work-rate cycling performed at different intensity domains

We aimed at examining the impact of wearing surgical face masks on exercise performance. Thirty-two healthy adults (16 males and 16 females) completed a graded exercise test to measure peak oxygen uptake (VO_2peak) and the ventilatory threshold (VT). Then, on separate days, all participants performed resting and standardized protocols (moderate intensity: 25% infra-VT; severe intensity: 25% supra-VT) on two different conditions (with and without a surgical mask). The use of masks reduced both VO₂ and minute ventilation during moderate and severe exercise (p < 0.0001), and this effect was particularly pronounced during severe exercise. Time to exhaustion was also shortened by ~10% on the face mask condition (p = 0.014). In contrast, neither heart rate nor the respiratory exchange ratio was affected by masking. The submaximal VO₂ was similar between the two epochs of analysis obtained during moderate cycling (i.e. 3–6 min vs. 7–10 min) and this occurred similarly between conditions. In conclusion, the impact of the surgical masks on exercise capacity is particularly pronounced during severe exercise performed at constant work rate. Ultimately, this may implicate a considerable impairment of structured or even unstructured strenuous physical activity. Clinical Trials registration number: NCT04963049.     

Determination of both the time constant of vO2 and DeltavO2/DeltaW from a single incremental exercise test: validation and repeatability

A single incremental cycle exercise test including a steady-state load, combined with respiratory gas exchange, was performed with the objective of determining the time constant (tauVO(2)) and the amount of oxygen required at each load (DeltaVO(2)/DeltaW) by using a novel equation. The protocol was validated using four exercise tests at different constant loads and conventionally fitted mono-exponential functions to determine tauVO(2), and interpolation of VO(2) versus load to determine DeltaVO(2)/DeltaW. No significant differences were seen between the means of either tauVO(2) or DeltaVO(2)/DeltaW determined with the two protocols. The correlation coefficient was 0.62 for tauVO(2) and 0.48 for DeltaVO(2)/DeltaW. The absolute differences (2 SD) were 11.6 s for tauVO(2) and 1.1 ml min(-1) W(-1) for DeltaVO(2)/DeltaW. The equations were compared in the same steady-state test and good agreement of tauVO(2) was obtained (R = 0.99). The 5-6-week repeatability (incremental test) was evaluated. No statistical differences were seen between the mean of the repeated tests. The difference between the tests (2 SD) were 20 s for tauVO(2) and 1.2 ml min(-1) W(-1) for DeltaVO(2)/DeltaW. In conclusion, tauVO(2) and DeltaVO(2)/DeltaW can be determined from a single incremental test. The validation showed an acceptable agreement, although the variations in absolute values were not negligible. This could partly be explained by the natural day-to-day variation and fluctuations in incoming raw data. The test-retest variation in absolute values was considerable, which must be taken into account when using tauVO(2) and DeltaVO(2)/DeltaW for evaluation of aerobic function.     

跑节省化、最大摄氧量评价普通人有氧耐力的效果比较

背景：尽管跑节省化、最大摄氧量在评价竞技运动员耐力上的差异已有定论,但有关普通人耐力水平的评价效果至今少有研究。目的：比较跑节省化与最大摄氧量在评价普通人群有氧耐力水平的效果。方法：以63名入伍新兵为测试对象,测定其最大摄氧量、跑节省化和5km跑成绩。最大摄氧量和跑节省化的测定采用逐级递增负荷运动方式在室内跑台上进行,坡度为O。。最大摄氧量的测定由8．5km／h的速度逐渐递增,直至力竭,满足最大摄氧量判定标准为止;跑节省化的测定由8．5km／h的速度增至11．5km／h并持续稳定3min,计算最后2min摄氧量的均值作为跑节省化值。采用Pearson积差相关法分析比较5km成绩同最大摄氧量、跑节省化之间的关系。结果与结论：当跑节省化采用相对值表示时,5km成绩与跑节省化值高度正相关（r=0．797,P=O．000）,而与最大摄氧量呈低度负相关（r=0．317,P=O．056）。另外,当前国民体质监测中常使用的台阶试验、室外800m／1000m跑等方法受到各种因素制约。结果证实,跑节省化在评价普通人群中表达有氧耐力上优于最大摄氧量,简单易行、可靠性高,在国民体质评价中具有明显优势。     

Home-based Neuromuscular Electrical Stimulation as an Add-on to Pulmonary Rehabilitation Does Not Provide Further Benefits in Patients With Chronic Obstructive Pulmonary Disease: A Multicenter Randomized Trial

Objective

To assess the additional effect of a home-based neuromuscular electrical stimulation (NMES) program as an add-on to pulmonary rehabilitation (PR), on functional capacity in subjects with chronic obstructive pulmonary disease (COPD).

The Association of Sleep Apnea and Cardiorespiratory Fitness With Long-Term Major Cardiovascular Events

ObjectiveTo determine the risk of long-term major adverse cardiovascular events (MACE) when sleep-disordered breathing (SDB) and decreased cardiorespiratory fitness (CRF) co-occur.MethodsWe included consecutive patients who underwent symptom-limited cardiopulmonary exercise tests between January 1, 2005, and January 1, 2010, followed by first-time diagnostic polysomnography within 6 months. Patients were stratified based on the presence of moderate-to-severe SDB (apnea/hypopnea index ≥15 per hour) and decreased CRF defined as <70% predicted peak oxygen consumption (VO₂). Long-term MACE was a composite outcome of myocardial infarction (MI), coronary artery bypass graft (CABG), percutaneous coronary intervention (PCI), stroke or transient ischemic attack (TIA), and death, assessed until May 21, 2018. Cox-proportional hazard models were adjusted for factors known to influence CRF and MACE.ResultsOf 498 included patients (60±13 years, 28.1% female), 175 (35%) had MACE (MI=17, PCI=14, CABG=13, stroke=20, TIA=12, deaths=99) at a median follow-up of 8.7 years (interquartile range=6.5 to 10.3 years). After adjusting for age, sex, beta blockers, systemic hypertension, diabetes mellitus, coronary artery disease, cardiac arrhythmia, chronic obstructive pulmonary disease, smoking, and use of positive airway pressure (PAP), decreased CRF alone (hazard ratio [HR]=1.91, 95% confidence interval [CI], 1.15 to 3.18; P=.01), but not SDB alone (HR=1.26, 95% CI, 0.75 to 2.13, P=.39) was associated with increased risk of MACE. Those with SDB and decreased CRF had greater risk of MACE compared with patients with decreased CRF alone (HR=1.85; 95% CI, 1.21 to 2.84; P<.005) after accounting for these confounders. The risk of MACE was attenuated in those with reduced CRF alone after additionally adjusting for adequate adherence to PAP (HR=1.59; 95% CI, 0.77 to 3.31; P=.21).ConclusionThe incidence of MACE, especially mortality, was high in this sample. Moderate-to-severe SDB with concurrent decreased CRF was associated with higher risk of MACE than decreased CRF alone. These results highlight the importance of possibly including CRF in the risk assessment of patients with SDB and, conversely, that of screening for SDB in patients with low peak VO₂.