Mid Sweden University

Introduction

Two frequently used approaches for estimating anaerobic energy production during supramaximal exercise are the maximal accumulated oxygen (O2) deficit (MAOD) method and the gross efficiency (GE) method (Noordhof et al., 2011). Despite clear computational differences between the two methods, only one direct comparison has been performed (Noordhof et al., 2011). In cross-country roller-skiing, both the MAOD and the GE methods have been employed (Andersson et al., 2016). Therefore, this study aimed to compare the O2 deficits attained with these methods.

Methods

Eleven male and ten female cross-country skiers were tested on a treadmill employing uphill (7°) diagonal-stride roller-skiing. After collecting a 1-min baseline VO2, participants performed a 4 × 4-min continuous submaximal protocol (~ 60-90% of VO2max) followed by, a self-paced 600-m time-trial (TT). Speed and VO2 were measured continuously during the TT. For the MAOD method, the linear relationship between treadmill velocity and VO2 during the final 30 seconds of each 4 × 4-min submaximal stage was derived with the baseline VO2 as a Y-intercept included (4+Y) in or excluded (4-Y) from the model. The two regression equations were then used to estimate the VO2 demand during the TT. For the GE method, the metabolic rate during the TT was calculated by taking the average power output divided by the GE (an average of the four submaximal stages) and converted to a VO2 demand. 

Results

The VO2 demand was significantly higher for the GE (68.9 ± 8.5 mL/kg/min) and 4-Y (68.4 ± 8.7 mL/kg/min) procedures compared with the 4+Y (64.3 ± 7.6 mL/kg/min) procedure (P < 0.05). The corresponding O2 deficits for the GE, 4-Y and, 4+Y procedures were 63.7 ± 9.7, 62.3 ± 10.4 and, 50.2 ± 9.6 mL/kg, respectively (P < 0.05 for GE and 4-Y vs. 4+Y). The mean difference between the O2 deficits estimated from the 4-Y and GE procedure -1.4 ± 3.9 mL/kg, and between the 4+Y and GE procedures was -13.5 ± 2.5 mL/kg.  Corresponding typical errors for the two comparisons were 2.74% and 1.74% while the intra-class correlation coefficients together with linear equations were r = 0.93 (0.99x – 0.8) for [4-Y vs. GE] and r = 0.97 (0.95x - 10.5) for [4+Y vs. GE].

Discussion

The main finding of the current study was the high agreement between the 4-Y and GE procedures which is in contrast to previous findings of Noordhof et al. (2011). Moreover, the inclusion of a Y-intercept for baseline VO2 resulted in a 20% lower O2 deficit compared to the 4-Y and GE procedures.  

References

Andersson E, Björklund G, Holmberg HC, Ørtenblad N. (2016). Scand J Med Sci Sports. Noordhof DA, Vink AM, de Koning JJ. Foster C. (2011). Int J Sports Med, 32, 422-8