Anaerobic work capacity in cycling: the effect of computational method

PURPOSE: To compare the anaerobic work capacity (AnWC, i.e., attributable anaerobic mechanical work) assessed using four different approaches/models applied to time-trial (TT) cycle-ergometry exercise. METHODS: Fifteen male cyclists completed a 7 × 4-min submaximal protocol and a 3-min all-out TT (TT(AO)). Linear relationships between power output (PO) and submaximal metabolic rate were constructed to estimate TT-specific gross efficiency (GE) and AnWC, using either a measured resting metabolic rate as a Y-intercept (7 + Y(LIN)) or no measured Y-intercept (7-Y(LIN)). In addition, GE of the last submaximal bout (GE(LAST)) was used to estimate AnWC, and critical power (CP) from TT(AO) (CP(3´AO)) was used to estimate mechanical work above CP (W’, i.e., “AnWC”). RESULTS: Average PO during TT(AO) was 5.43 ± 0.30 and CP was 4.48 ± 0.23 W∙kg(−1). The TT-associated GE values were ~ 22.0% for both 7 + Y(LIN) and 7-Y(LIN) and ~ 21.1% for GE(LAST) (both P < 0.001). The AnWC were 269 ± 60, 272 ± 55, 299 ± 61, and 196 ± 52 J∙kg(−1) for the 7 + Y(LIN), 7-Y(LIN), GE(LAST), and CP(3´AO) models, respectively (7 + Y(LIN) and 7-Y(LIN) versus GE(LAST), both P < 0.001; 7 + Y(LIN), 7-Y(LIN), and GE(LAST) versus CP(3´AO), all P < 0.01). For the three pair-wise comparisons between 7 + Y(LIN), 7-Y(LIN), and GE(LAST), typical errors in AnWC values ranged from 7 to 11 J∙kg(−1), whereas 7 + Y(LIN), 7-Y(LIN), and GE(LAST) versus CP(3´AO) revealed typical errors of 55–59 J∙kg(−1). CONCLUSION: These findings demonstrate a substantial disagreement in AnWC between CP(3´AO) and the other models. The 7 + Y(LIN) and 7-Y(LIN) generated 10% lower AnWC values than the GE(LAST) model, whereas 7 + Y(LIN) and 7-Y(LIN) generated similar values of AnWC.