Characterization of the work-time relationship during cross-country ski ergometry

The purpose of this study was to examine the validity and reliability of estimated parameters of the work-time relationship during cross-country ski ergometry using the traditional multi-trial critical power (CP) test and a 3 min 'all-out' test (3MT). Fourteen recreationally active male participants (mean ± SD; age: 22.14 ± 2.85 yrs; height: 177.09 ± 6.57 cm; weight: 85.68 ± 13.56 kg) completed three testing visits. All testing was conducted using an upper-body ergometer (SkiErg, Concept2, Inc., Morrisville, VT). A graded exercise test was used to determined maximal oxygen uptake (VO2peak). Two separate 3MT sessions were used to determine oxygen uptake (VO23MT), end-test power (EP), work above end-test power (WEP) and end stroke rate (ESR). Additionally, three time trials completed in a single day at simulated distances of 300 m, 650 m and 1000 m were used to estimate CP, W' and critical stroke rate (CSR). VO2peak (3.65 ± 0.50 l · min(-1)) and VO23MT (3.59 ± 0.4 l · min(-1)) were not significantly different (p = 0.162). Intraclass correlation coefficients for EP, WEP and ESR were 0.809, 0.611 and 0.783, respectively. EP (148 ± 33 W) and CP (157 ± 49 W), were not significantly different between the testing methodologies (p = 0.290) and were highly correlated (r = 0.780). WEP (8.4 ± 3.0 kJ) and W' (8.3 ± 3.0 kJ) were similar (p = 0.947) but not related (r = 0.119), while ESR (45 ± 7 spm) and CSR (47 ± 7 spm) values were not significantly different (p = 0.238) and moderately correlated (r = 0.498). The 3MT using ski ergometry was shown to produce concurrently valid results with the traditional multi-trial CP test for CP and CSR, but not W', and elicited similar maximal oxygen uptake values when compared to a graded exercise test.