Date Published: October 11, 2018
Publisher: Public Library of Science
Author(s): Hendrik Mugele, Ashley Plummer, Omar Baritello, Maggie Towe, Pia Brecht, Frank Mayer, Caroline Sunderland.
Competitive runners will occasionally undergo exercise in a laboratory setting to obtain predictive and prescriptive information regarding their performance. The present research aimed to assess whether the physiological demands of lab-based treadmill running (TM) can simulate that of over-ground (OG) running using a commonly used protocol. Fifteen healthy volunteers with a weekly mileage of ≥ 20 km over the past 6 months and treadmill experience participated in this cross-sectional study. Two stepwise incremental tests until volitional exhaustion was performed in a fixed order within one week in an Outpatient Clinic research laboratory and outdoor athletic track. Running velocity (IATspeed), heart rate (IATHR) and lactate concentration at the individual anaerobic threshold (IATbLa) were primary endpoints. Additionally, distance covered (DIST), maximal heart rate (HRmax), maximal blood lactate concentration (bLamax) and rate of perceived exertion (RPE) at IATspeed were analyzed. IATspeed, DIST and HRmax were not statistically significantly different between conditions, whereas bLamax and RPE at IATspeed showed statistical significance (p < 0.05). Apart from RPE at IATspeed, IATspeed, DIST, HRmax and bLamax strongly correlate between conditions (r = 0.815–0.988). High reliability between conditions provides strong evidence to suggest that running on a treadmill are physiologically comparable to that of OG and that training recommendations and be made with assurance.
General exercise examinations such as multistage incremental exercise testing (IET) are common practice for assessing recreational and professional athletes . IET can be used to identify current training status, predict performance capability and help to give training recommendations [1,2]. There are several field and laboratory protocols that are currently implemented and consist of many differentiating variables including stage duration, number of stages, speed increments, starting velocities and inclinations [3,4]. In clinical exercise science, the use of motorized treadmills in a laboratory setting is a widely accepted method as it is well standardized, reproducible and facilitates the measurement of targeted performance parameters, e.g. heart rate, ventilation and blood lactate (bLa) .
The aim of the study was to assess whether the inclination used on a motorized treadmill was sufficient to give valid training recommendations. The primary finding demonstrated that applying a 0.4% gradient is strongly correlated with the over-ground condition as expressed by IATspeed. Additionally, the distance covered by the runners was also highly correlated between conditions. To the knowledge of the authors’, this study represents the first to compare the IATspeed in both a laboratory and outdoor setting using the same stepwise incremental protocol.
The results reconfirm that prescriptions based on laboratory testing are accurate due to the high reliability of IATspeed between the TM and RT conditions. Although not generalizable, the current study shows that revalidation of used protocols and facilities are mandatory to prescribe valid and up to date training recommendations to athletes and patients alike. This study offers a methodological approach whereby institutions can routinely revalidate their own treadmill-based recommendations.