Interrater reliability of a customized submaximal cycle ergometer test

Graded exercise testing (GXTs) is used to determine maximum oxygen uptake (\(\dot{V}{\text{O}}_{{2\max }}\)). Recently, customized submaximal exercise testing (CSET) completed on both treadmill and cycle ergometry were validated.

Interrater reliability of the CSET for cycle ergometry was examined. Thirteen participants (age 31 ± 10.2 y, weight 77.9 ± 10.5 kg, height 176.2 ± 9.9 cm, body mass index 25.1 ± 2.9) completed the 2-stage × 3-min CSET protocol performed by two separate testers. True \(\dot{V}{\text{O}}_{2\mathrm{max}}\) was determined using the highest value derived by a GXT and verification bout. Skeletal muscle oxygen saturation (\(\dot{S}m{O}_{2}\)), measured using near-infrared spectrometry on the medial gastrocnemius muscle, and \(\dot{V}{\text{O}}_{2}\) were monitored during each CSET; whereby, \(\dot{V}{\text{O}}_{2}\) kinetics were modeled breath-by-breath data for each 3-min stage. Measurement agreement was quantified using intraclass coefficient (ICC), typical error (TE), and coefficient of variation (CV).

“True” \(\dot{V}{\text{O}}_{2\mathrm{max}}\) (ml·kg⁻¹·min⁻¹) between the GXT (41.3 ± 10.5) and verification (42.5 ± 11.5) was established (ICC = 0.98, TE: 0.98, CV 2.1%). Estimated \(\dot{V}{\text{O}}_{2\mathrm{max}}\) by tester 1 (42.5 ± 9.8) and tester 2 (42.7 ± 8.9) did not differ from “true” \(\dot{V}{\text{O}}_{2\mathrm{max}}\) (F_2,36 = 0.02, p = 0.98, η_p² = 0.00). The second stage evoked a \(\dot{V}{\text{O}}_{2}\) slow component of 194 ± 124 ml·min⁻¹ that corresponded with a time-dependent decline of \(\dot{S}m{O}_{2}\). The mean \(\dot{S}m{O}_{2}\) from the two CSET testers were highly correlated (ICC = 0.91, TE: 4.1%, CV = 8.9%).

The CSET is a reliable and valid procedure and \(\dot{S}m{O}_{2}\) is a useful tool for corroborating the second stage is in the heavy-intensity domain.