Confirming the attainment of maximal oxygen uptake within special and clinical groups: A systematic review and meta-analysis of cardiopulmonary exercise test and verification phase protocols.

BACKGROUND AND AIM: A plateau in oxygen uptake ([Formula: see text]) during an incremental cardiopulmonary exercise test (CPET) to volitional exhaustion appears less likely to occur in special and clinical populations. Secondary maximal oxygen uptake ([Formula: see text]) criteria have been shown to commonly underestimate the actual [Formula: see text]. The verification phase protocol might determine the occurrence of 'true' [Formula: see text] in these populations. The primary aim of the current study was to systematically review and provide a meta-analysis on the suitability of the verification phase for confirming 'true' [Formula: see text] in special and clinical groups. Secondary aims were to explore the applicability of the verification phase according to specific participant characteristics and investigate which test protocols and procedures minimise the differences between the highest [Formula: see text] values attained in the CPET and verification phase. METHODS: Electronic databases (PubMed, Web of Science, SPORTDiscus, Scopus, and EMBASE) were searched using specific search strategies and relevant data were extracted from primary studies. Studies meeting inclusion criteria were systematically reviewed. Meta-analysis techniques were applied to quantify weighted mean differences (standard deviations) in peak [Formula: see text] from a CPET and a verification phase within study groups using random-effects models. Subgroup analyses investigated the differences in [Formula: see text] according to individual characteristics and test protocols. The methodological quality of the included primary studies was assessed using a modified Downs and Black checklist to obtain a level of evidence. Participant-level [Formula: see text] data were analysed according to the threshold criteria reported by the studies or the inherent measurement error of the metabolic analysers and displayed as Bland-Altman plots. RESULTS: Forty-three studies were included in the systematic review, whilst 30 presented quantitative information for meta-analysis. Within the 30 studies, the highest mean [Formula: see text] values attained in the CPET and verification phase protocols were similar (mean difference = -0.00 [95% confidence intervals, CI = -0.03 to 0.03] L·min-1, p = 0.87; level of evidence, LoE: strong). The specific clinical groups with sufficient primary studies to be meta-analysed showed a similar [Formula: see text] between the CPET and verification phase (p > 0.05, LoE: limited to strong). Across all 30 studies, [Formula: see text] was not affected by differences in test protocols (p > 0.05; LoE: moderate to strong). Only 23 (53.5%) of the 43 reviewed studies reported how many participants achieved a lower, equal, or higher [Formula: see text] value in the verification phase versus the CPET or reported or supplied participant-level [Formula: see text] data for this information to be obtained. The percentage of participants that achieved a lower, equal, or higher [Formula: see text] value in the verification phase was highly variable across studies (e.g. the percentage that achieved a higher [Formula: see text] in the verification phase ranged from 0% to 88.9%). CONCLUSION: Group-level verification phase data appear useful for confirming a specific CPET protocol likely elicited [Formula: see text], or a reproducible [Formula: see text], for a given special or clinical group. Participant-level data might be useful for confirming whether specific participants have likely elicited [Formula: see text], or a reproducible [Formula: see text], however, more research reporting participant-level data is required before evidence-based guidelines can be given. TRIAL REGISTRATION: PROSPERO (CRD42021247658) https://www.crd.york.ac.uk/prospero.

Comparison of Physiological and Biomechanical Responses to Flat and Uphill Cross-Country Sit-Skiing in Able-Bodied Athletes.

PURPOSE: To compare peak work rate (WRpeak) and associated physiological and biomechanical performance-determining variables between flat and uphill cross-country (XC) sit-skiing. METHODS: Fifteen able-bodied male XC skiers completed 2 test sessions, each comprising four 4-minute submaximal stages, followed by an incremental test to exhaustion and a verification test in a sit-ski on a roller-ski treadmill. The test sessions were counterbalanced by the incline, being either 0.5% (FLAT) or 5% (UPHILL). The authors compared WRpeak and peak oxygen uptake, as well as physiological variables, rating of perceived exertion, gross efficiency, and cycle characteristics at identical submaximal work rate, between FLAT and UPHILL. RESULTS: In UPHILL, WRpeak was 35% higher compared to FLAT (P < .001), despite no difference in peak oxygen uptake (P = .9). The higher WRpeak in UPHILL was achieved through more work per cycle, which was enabled by the twice as long poling time, compared to FLAT (P < .001). Submaximal gross efficiency was 0.5 to 2 percentage points lower in FLAT compared to UPHILL (P < .001), with an increasing difference as work rate increased (P < .001). Neither cycle rate nor work per cycle differed between inclines when compared at identical submaximal work rate (P > .16). CONCLUSIONS: The longer poling times utilized in uphill XC sit-skiing enable more work per cycle and better gross efficiency, thereby allowing skiers to achieve a higher WRpeak compared to flat XC sit-skiing. However, the similar values of peak oxygen uptake between inclines indicate that XC sit-skiers can tax their cardiorespiratory capacity similarly in both conditions.

Comparison of Race Time-Differences Between and Within Para and Able-Bodied Cross-Country Skiers.

PURPOSE: To compare differences in race time (i.e., the average percent difference in race time for each skier compared to the winner, RTdiffs) between female and male Para and able-bodied (AB) skiers, and to examine whether RTdiffs change across seasons. METHODS: Race data from World Cups (WCs), World Championships (WCHs), and Paralympic/Olympic Winter Games (PWG/OWGs) of the 2011-2020 seasons was extracted from the website of the International Paralympic Committee and the International Ski Federation. All individual distance races for female and male visually impaired standing (VI), physically impaired sitting (SIT) and standing (STAND), and AB skiers with ≥10 competitors were included in the analyses. We investigated the main effect of skiing groups (i.e., VI, STAND, SIT, and AB skiers) and sex on RTdiffs for top-3 and top-8 skiers. Furthermore, the main effect of season and skiing group on RTdiffs for top-3 and top-8 skiers were investigated. All models were adjusted for distance, skiing style (classical- and freestyle), and event type (WC, WCH, and PWG/OWG). RESULTS: RTdiffs were significantly larger in Para compared to AB skiers (top-3: 2.1 vs. 0.9%; top-8: 6.2 vs. 2.1%, all p < 0.01), and in female compared to male skiers (top-3: 1.8 vs. 1.3%; top-8: 4.9 vs. 3.5%, all p < 0.05). For top-3 skiers, RTdiffs did not significantly differ between the Para categories (all p > 0.2), while for top-8 skiers RTdiffs were significantly larger for VI compared to SIT and STAND (7.0 vs. 5.5 and 5.6%, respectively, all p < 0.05). RTdiffs were stable across the 2011-2020 seasons for top-3 skiers (VI: 1.7-3.6%, STAND: 1.1-2.2%, SIT: 1.0-3.9%, AB: 0.4-1.1%; all p > 0.1) and top-8 skiers (VI: 3.4-12.0%, STAND: 2.6-5.7%, SIT: 1.9-5.9%, AB: 0.1-1.7%; all p > 0.1). CONCLUSION: The larger RTdiffs in Para compared to AB skiers indicate larger variability in performance, which are in part disability related. Female skiers displayed larger RTdiffs than their male counterparts, indicating larger variability in performance among the female skiers. Our results provide insights about performance demands in Para cross-country skiing, which is of relevance for coaches and skiers.

Corrigendum: Comparison of Peak Oxygen Uptake and Test-Retest Reliability of Physiological Parameters between Closed-End and Incremental Upper-Body Poling Tests.

[This corrects the article DOI: 10.3389/fphys.2017.00857.].

Comparison of Peak Oxygen Uptake and Test-Retest Reliability of Physiological Parameters between Closed-End and Incremental Upper-Body Poling Tests.

Objective: To compare peak oxygen uptake (VO2peak) and the test-retest reliability of physiological parameters between a 1-min and a 3-min closed-end and an incremental open-end upper-body poling test. Methods: On two separate test days, 24 healthy, upper-body trained men (age: 28.3 ± 9.3 years, body mass: 77.4 ± 8.9 kg, height: 182 ± 7 cm) performed a 1-min, a 3-min and an incremental test to volitional exhaustion in the same random order. Respiratory parameters, heart rate (HR), blood lactate concentration (BLa), rating of perceived exertion (RPE), and power output were measured. VO2peak was determined as the single highest 30-s average. Relative reliability was assessed with the intra-class correlation coefficient (ICC2, 1) and absolute reliability with the standard error of measurement (SEM) and smallest detectable change (SDC). Results: The incremental (3.50 ± 0.46 L·min-1 and 45.4 ± 5.5 mL·kg-1·min-1) and the 3-min test (3.42 ± 0.47 L·min-1 and 44.5 ± 5.5 mL·kg-1·min-1) resulted in significantly higher absolute and body-mass normalized VO2peak compared to the 1-min test (3.13 ± 0.40 L·min-1 and 40.4 ± 5.0 mL·kg-1·min-1) (all comparisons, p < 0.001). Furthermore, the incremental test resulted in a significantly higher VO2peak as compared to the 3-min test (p < 0.001). VO2peak was significantly higher on day 1 than day 2 for the 1-min test (p < 0.05) and displayed a trend toward higher values on day 2 for the incremental test (p = 0.07). High and very high ICCs across all physiological parameters were found for the 1-min (0.827-0.956), the 3-min (0.916-0.949), and the incremental test (0.728-0.956). The SDC was consistently small for HR (1-min: 4%, 3-min: 4%, incremental: 3%), moderate for absolute and body-mass normalized VO2peak (1-min: 5%, 3-min: 6%, incremental: 7%) and large for BLa (1-min: 20%, 3-min: 12%, incremental: 22%). Conclusions: Whereas both the 3-min and the incremental test display high relative reliability, the incremental test induces slightly higher VO2peak. However, the 3-min test seems to be more stable with respect to day-to-day differences in VO2peak. The 1-min test would provide a reliable alternative when short test-duration is desirable, but is not recommended for testing VO2peak due to the clearly lower values.