Mid Sweden University

INTRODUCTION: Incremental tests to volitional exhaustion are widely used to assess VO₂max. However, the need to establish starting workloads, stage durations, and step increments make administration problematic. Moreover, the validity of such tests has been questioned (Beltrami et al., 2012, Br J Sports Med, 46:23-29; Mauger & Sculthorpe, 2012, Br J Sports Med, 46:59-63). Short time trials represent a simpler and more ecologically valid alternative to assess VO₂max and performance across exercise modes (Crouter et al., 2001, Med Sci Sports Exerc, 33:644-647; Ansley et al., 2004, Med Sci Sports Exerc, 36:1819-1825; McGawley & Holmberg, 2014, Int J Sports Physiol Perform 9:32-40). The aim of the current study was to assess the reliability and validity of a treadmill running time trial (RunTT) for the assessment of VO₂max and performance.

METHODS: Ten recreational athletes (5 males, 5 females; 32 ± 7 y) completed five incremental tests to exhaustion (INC) including a verification phase (VER) on a treadmill and five, 4-min RunTTs. The order of INC+VER and RunTT trials was alternated and counter-balanced. The INC and VER protocols were externally controlled, with incline increasing by 1% every minute during the INC. By contrast, the RunTT protocol was athlete controlled, with running speed self-adjusted via a laser system fitted to the treadmill (and incline fixed at 1%). Performance was measured as time to exhaustion for INC and VER and distance covered for RunTT. Heart rate (HR) was monitored continuously throughout each protocol. RPE and lactate were assessed immediately post-exercise and at 1-min intervals for four minutes post-exercise, respectively.

RESULTS: The CV for VO₂max was not significantly different between INC, VER and RunTT (1.9, 2.2 and 1.7%, respectively) but for performance was significantly different between all types of test (4.5, 9.7 and 1.8% for INC, VER and RunTT, respectively; P<0.005). VO₂max was significantly higher for INC compared with VER and RunTT (59.2 versus 58.0 and 57.6 mL/kg/min, respectively; P<0.001) and Bland-Altman limits of agreement showed a bias ± 95% of 1.5 ± 3.1 mL/kg/min for INC versus RunTT. Peak HR was also significantly higher for INC compared with RunTT (181 versus 177 beats/min; P<0.001), while peak RER and RPE were not different. Peak lactate was higher after RunTT compared with INC (10.13 versus 9.22 mmol/L; P<0.001).

CONCLUSION: A RunTT appears to provide more reliable performance data in comparison to INC; however, VO₂max values were ~ 1.5 mL/kg/min lower and peak lactate was significantly higher.