Author(s): BOULAY, P., GENDRON, P.1, MCCORMICK, J.2, KENNY, G.P.2, Institution: UNIVERSITÉ DE SHERBROOKE, Country: CANADA, Abstract-ID: 1595

INTRODUCTION:
Cardiorespiratory fitness (CRF) is a key clinical marker in older adults, with low CRF consistently associated with increased premature mortality and adverse health outcomes comparable to traditional cardiovascular disease (CVD) risk factors. Given these implications, accurate assessment is essential. A supramaximal verification phase following a traditional incremental exercise test has been proposed to confirm the attainment of true maximal oxygen uptake (VO2max). This study therefore aimed to 1) assess whether a supramaximal verification phase confirms VO2max attainment in older adults at low and high risk of CVD, and 2) determine the impact of different time-sampling intervals on the interpretation of VO2max results.
METHODS:
Data from 69 maximal cycle ergometer (Corival, Lode) tests performed by older adults were analyzed (25 females; 44 males; 69.8±5.6 [60-84] yrs; 59.4% with CVD risk factors). Tests were considered maximal if fatigue-limited and associated with respiratory exchange ratio (RER) >1.1. Following at least 5 minutes of recovery, participants completed a supramaximal verification phase at a power output 20% greater than the penultimate stage of the incremental maximal exercise test. VO2max from the incremental exercise test (iVO2max) and verification phase (verVO2max) were calculated using 10-seconds (s), 20-s, and 30-s from breath-by-breath averaging intervals (MCD Medgraphics, MGC Diagnostics). Data were analyzed using repeated measures ANOVA with Bonferroni correction and paired t-tests.
RESULTS:
Participants achieved a peak power output of 161.0±58.8 Watts, a maximal heart rate of 153±15 bpm, and a peak RER of 1.24±0.06. During the incremental test, 60.8% of participants (n=42) demonstrated a VO2 plateau (increase of <100 mlO2.min-1 with increasing workload). Total exercise time averaged 542.8±149.3s for the iVO2max and 130.8±25.3s for verVO2max tests. Mean iVO2max and verVO2max did not differ significantly across sampling intervals of 10-s (26.73±6.95 vs 26.77±6.97 mlO2.min-1.kg-1), 20-s (26.57±6.92 vs 26.51±6.97 mlO2.min-1.kg-1), and 30-s (26.42±6.91 vs 26.31±6.99 mlO2.min-1.kg-1), respectively (all p>0.05). However, 10-s averages yielded significantly higher VO2max than 30-s averaging for both test phases (p<0.001). Notably, individual analysis revealed that 13 participants (≈19%) increased VO2max by more than 1.5 mlO2.min-1.kg-1 and 24.6% by >3% during the verification phase.
CONCLUSION:
These findings support the use of a supramaximal verification phase to confirm VO2max attainment in older adults. Sampling interval duration did not influence verification success; however, shorter averaging (10-s) yielded statistically higher, though clinically negligible, VO2max values. Notably, despite stable group means, ≈19% of participants demonstrated a significant increase in their VO2max during the verification phase. This has important implications for intervention studies that use repeated VO2max assessments to detect training-induced changes in CRF.