However, data presented in this study indicate that a verification phase performed subsequent to the end of a RI test does not provide a convincing confirmation that a true V˙O2max response has been achieved. Therefore, the recommendation that a verification phase should become the gold standard procedure for V˙O2max determination, although initially appealing, is not supported. Data from the present study indicated that, in 61 older and younger participants, the average highest V˙O2 values observed during the RI tests and the verification phase were similar, irrespective of age, fitness level and verification phase intensity.
Participants were instructed not to engage in any form of intensive exercise and to discontinue training 24 hours prior to the test. Cyclists were familiarized with the experimental protocol, each of them having previously been tested at our laboratory. A randomly selected half of the participants executed the incremental test first and the ramp test one week later. The other participants proceeded in the reverse order.
One caveat when interpreting the findings presented above regarding verification bouts is that this research was performed on participants who were physically active. The lack of information on sedentary individuals in the literature is perhaps surprising given the prevailing sedentarism and the use of ⩒o2max assessment for individuals who are unaccustomed to exercise (e.g., those that would more likely be found in the clinical setting). Furthermore, the belief that a CWR bout is required to verify ⩒o2peak as ⩒o2max in lieu of a ⩒o2 plateau is based on the contention that often-used “secondary criteria” (e.g., threshold values for RER, heart rate, RPE and/or blood lactate concentration) are not valid for this purpose.
Ventilation threshold
Once RAMP-INC was terminated, participants performed cool-down cycling at 25 W for 10 min after which they rested on the ergometer for a 2–3 min period that was required for the CWR work rate to be programmed. Participants then resumed pedaling at 100% of the WRpeak from RAMP-INC and continued to do so until they reached Tlim. The cadence and termination criterion for the CWR bout was the same as that which was used for RAMP-INC (see above). For example, Sawyer et al. investigated sedentary individuals with obesity and found no significant difference between the ⩒o2peak during RAMP-INC and that which they measured during a CWR bout like the one we employed (i.e., performed 5–10 min later at 100% WRpeak) [26]. However, in that study, 13 of 19 participants achieved a value during CWR that was ≥ 2% higher (range, 2.0–21.0%; 0.04–0.47 L∙min-1) [26]. Astorino et al. performed two different assessments of sedentary individuals and found no significant difference between the ⩒o2peak values for RAMP-INC and CWR [27].
It appears indispensable to keep searching for reliable methods of adequate and rapid assessment of FATmax, FATmin and MFO. In conclusion, the accurate identification of V˙O2max remains an elusive issue and there is a clear need for developing reliable criteria to objectively evaluate the achievement of a true maximal response. In this context, the proposal by Poole and Jones (2017) to use the verification phase for true V˙O2max determination appeared a very promising approach to overcome the absence of an objective plateau in V˙O2.
- Achten et al. (2002) suggest that 3-min stages are optimal to reach a state of equilibrum and define MFO for well-trained athletes.
- Strength training and determinants of V˙O2max in older men.
- This is the first study which verifies whether the linear protocol of incremental RAMP tests performed on a cycle-ergometer may constitute a reliable assessment method of fat oxidation and exercise intensity at which it occurs at its maximal and minimal rate.
- Hence, to further investigate the difference that was observed between measurements from the two tests, we examined limits of agreement between measurements and individual-subject data.
- After initial telephone screening, prospective participants visited the laboratory for a comprehensive medical examination that included blood work, an ECG and an oral glucose tolerance test.
Both tests were executed at the same time of day (8.00 – 11.00) under laboratory conditions so as to avoid daily variation. Participants were also requested to avoid consuming caffeine 24 hours prior to each experimental session. Cyclists reported to the laboratory after having abstained from eating the whole night (11 ± 1 h). To control the influence of diet on metabolism during exercise, cyclists ate meals provided at the Academies cafeteria. This standardization method entails a significant variability in food intake between the subjects (Jeacocke and Burke, 2010).
AJ reviewed and commented on all previous versions of the manuscript. The authors would like to thank prof. Wojciech Zatoń for translation and the subjects participating in the study and their coaches.
Incremental and decremental cardiopulmonary exercise testing protocols produce similar maximum oxygen uptake in athletes
The two-test sequence was performed on an electronically-braked cycle ergometer (VIAsprint 150P, Ergoline, Bitz, Germany). The RAMP-INC began with 4 min of unloaded “baseline” cycling followed by an increase in work rate of 1 W every 3 or 4 s for male and female participants, respectively. Participants maintained a pedal cadence of 60 ± 2 rpm during both cycling bouts and the tests were terminated when this cadence was unable to be maintained for ≥ 10 s despite strong verbal encouragement. Verbal encouragement throughout the tests was based on the 20-s protocol advanced by Andreacci et al. (2002) [19].
Controversy surrounds methods that have been employed for this purpose. One option is to extend the testing session with a constant-work-rate “verification bout” (CWR) performed at a work rate situated in the “severe-intensity domain” within which attainment of ⩒o2max is an inevitable consequence of exercise maintained to Tlim [6]. The ⩒o2peak recorded during a severe-intensity CWR bout can be used to test for the presence of a plateau [7, 8] as long as the work rate can be sustained long enough for ⩒o2max to be reached; i.e., is not situated in the extreme-intensity domain [9]. However, Murias et al. (2018) recently argued that verification bouts are not necessary because they do not reveal a significantly different ⩒o2peak compared to RAMP-INC for recreationally-active younger and older males [10]. They also reason that in contrast to indicating that the ⩒o2peak during INC is the “true ⩒o2max,” agreement between measurements might simply reflect the fact that participants chose to cease exercise at a similar level of submaximal fatigue (and, by extension, a submaximal ⩒o2 that was not significantly different) during both tests. Hence, they suggest that if a severe-intensity CWR bout is performed following INC, the extent of its usefulness is to identify participants who did not achieve their highest ⩒o2peak on INC as opposed to verifying ⩒o2max for individuals who did.
ORIGINAL RESEARCH article
These findings confirm, in a larger and more heterogeneous population, the findings of others (Rossiter et al., 2006; Astorino et al., 2009; Barker et al., 2011; Sedgeman et al., 2013; Nolan et al., 2014; Sawyer et al., 2015). In addition, our study provides the first data of this type in an older adult population. Furthermore, individual differences between the RI test and the verification phase displayed quantitatively negligible (likely unmeasurable) and not significant bias. The results are similar to those in an athlete sample in whom the V˙O2 from RI and verification phase were not different, and within the error of measurement in 24 out of 24 subjects (Weatherwax et al., 2016). The experiment comprised two visits to the laboratory during which anthropometric measurements were followed by progressive tests on a cycle-ergometer with an analysis of expiratory gases and the heart rate.
Hence, to further investigate the difference that was observed between measurements from the two tests, we examined limits of agreement between measurements and individual-subject data. In the present study, a positive bias was present (0.98 mL∙min-1∙kg-1 or 3.4% of the RAMP-INC value; see Fig 3) with 23 of 35 participants registering a higher ⩒o2peak on CWR. Importantly, 16 of these 23 demonstrated a value that was ≥ 3% higher, which should account for the influence of biological variability that is inherent with ⩒o2max measurements [7].
(i) a RI test may fail to provide a true V˙O2max; (ii) an upper limit to V˙O2 exists and this value can only be underestimated but not overestimated; (iii) during a constant load exercise to the limit of tolerance in the very heavy/severe domain, V˙O2 will project to V˙O2max within the time of task failure. Therefore, according to Rossiter et al. (2006), the lack of significant differences in the V˙O2 response of the constant load verification phase, both at 95 and 105% of peak PO, compared to the highest V˙O2 observed during the RI test, would provide the objective “plateau criterion” that often remains elusive during a RI test and confirm that a maximal value was obtained. Importantly, this protocol not only corroborated the presence of an upper limit of the V˙O2 response, but it also indicated that the highest V˙O2 values obtained during a RI were not different from those observed during the verification phase and likely reflected the achievement of a true V˙O2max. In the present study, we found that participants achieved a significantly higher ⩒o2peak during CWR cycling in the severe-intensity domain compared to that which they achieved during a RAMP-INC cycling test when both bouts were performed to the limit of exercise tolerance. However, given inherent biological variability in the measurement of ⩒o2max, using grouped data (i.e., in this case, a significant difference between group means) to support such a difference (or lack thereof) has been criticized [21].
This interpretation is not surprising; exercising within the very heavy intensity domain (such as in Sedgeman et al. and the present studies) is compatible with a longer exercise duration, in turn allowing enough time for the slow component of V˙O2 to develop and for V˙O2max to be achieved. We evaluated a short-duration maximum exercise test by comparing a 15-s incremental exercise protocol with a 1-min incremental method. Twenty normal men and women were studied using cycle and/or treadmill ergometry.
It was important to verify the usefulness of the verification phase in the same population in which the verification phase has been proposed; however, the absence of female participants in this study is an issue that, although not expected to change the outcome observed in the present investigation, might need to be addressed in future studies. Recently, a review by Poole and Jones (2017) proposed the idea that the denomination of “peak” V˙O2 (V˙O2peak) is no longer acceptable and that validated V˙O2max results, as derived from a verification phase, should be presented in all future studies. An important point raised by Poole and Jones (2017) is that even though https://www.globalcloudteam.com/ the RI test might yield a highly reproducible V˙O2max response in active or trained participants who are accustomed to pushing themselves to exhaustion, this may not be the case with less experienced, unmotivated, and/or clinical populations. Thus, even though a RI test might provide a trustable measure of V˙O2max in trained individuals, a verification phase should always be performed in any population unaccustomed to pushing to the upper limits of tolerance. Exercise physiologists have been interested in the measurements of oxygen uptake (V˙O2) and maximal V˙O2 (V˙O2max) since early in the 20th century (Krogh and Lindhard, 1913; Hill and Lupton, 1923).
This is the first study which verifies whether the linear protocol of incremental RAMP tests performed on a cycle-ergometer may constitute a reliable assessment method of fat oxidation and exercise intensity at which it occurs at its maximal and minimal rate. The results obtained corroborated the reliability of the RAMP test in measuring MFO in youth road cyclists. The main conclusion reached is the absence of MFO variance between the tests as well as the relative exercise intensities at FATmax and FATmin.
