The Dynamics of Speed Selection and Psycho-Physiological Load during a Mountain Ultramarathon

Abstract

BackgroundExercise intensity during ultramarathons (UM) is expected to be regulated as a result of the development of psycho-physiological strain and in anticipation of perceived difficulties (duration, topography). The aim of this study was to investigate the dynamics of speed, heart rate and perceived exertion during a long trail UM in a mountainous setting.MethodsFifteen participants were recruited from competitors in a 106 km trail mountain UM with a total elevation gain and loss of 5870 m. Speed and gradient, heart rate (HR) and ratings of perceived exertion (dissociated between the general [RPEGEN] and knee extensor fatigue [RPEKE] and collected using a voice recorder) were measured during the UM. Self-selected speed at three gradients (level, negative, positive), HR, RPEGEN and RPEKE were determined for each 10% section of total event duration (TED).ResultsThe participants completed the event in 18.3 ± 3.0 h, for a total calculated distance of 105.6 ± 1.8 km. Speed at all gradients decreased, and HR at all gradients significantly decreased from 10% to 70%, 80% and 90%, but not 100% of TED. RPEGEN and RPEKE increased throughout the event. Speed increased from 90% to 100% of TED at all gradients. Average speed was significantly correlated with total time stopped (r = -.772; p = .001; 95% confidence interval [CI] = -1.15, -0.39) and the magnitude of speed loss (r = .540; p = .038; 95% CI = -1.04, -0.03), but not with the variability of speed (r = -.475; p = .073; 95% CI = -1.00, 0.05).ConclusionsParticipants in a mountain UM event combined positive pacing strategies (speed decreased until 70–90% of TED), an increased speed in the last 10% of the event, a decrease in HR at 70–90% of TED, and an increase in RPEGEN and RPEKE in the last 30% of the event. A greater speed loss and less total time stopped were the factors associated with increased total performance. These results could be explained by theoretical perspectives of a complex regulatory system modulating motor drive in anticipation of perceived difficulties such as elevation changes.

Pacing during an ultramarathon running event in hilly terrain

“…In contrast to these findings, we measured in a previous study on trained UM runners a higher magnitude of speed loss in faster compared to slower runners, no significant relationship between the variability of speed and performance level, and a novel significant negative relationship between the total time stopped and performance level, in a long mountain UM (Kerhervé, Millet & Solomon, 2015). Additionally, speed on level, uphill and downhill sections increased in the last 10% of the event.…”

“…A recent study from our group also reported parabolic pacing during a 105 km mountain UM, characterised by a decrease of speed at all gradient categories in the later stages of the event (70–90% of total event duration), and by a final increase in speed in the last 10% of the event (Kerhervé, Millet & Solomon, 2015). The presence of an increase in speed in the last 10% section of the event was discussed as an indicator of conservative pacing strategies in anticipation of upcoming topographic difficulties, and the use of a speed reserve (Millet, 2011) when the last topographic difficulty was passed.…”

“…While speed loss and total time stopped were found to be significantly correlated with performance in a mountain UM (Kerhervé, Millet & Solomon, 2015), speed loss and speed variability were found to be significantly correlated with performance obtained in marathon (Ely et al, 2008; Haney & Mercer, 2011) and UM (Hoffman, 2014; Lambert et al, 2004) running. Therefore, additional research is required to determine if specific pacing characteristics are useful predictors of performance in long UM, and whether other variables currently not measured could be better predictors of pacing, including but variables of gait kinematics (stride frequency, stride length, ground contact and aerial times) or gait biomechanics (leg and vertical stiffness), which are known to be influenced by fatigue and gradient (Morin, Samozino & Millet, 2011a; Morin et al, 2011b; Vernillo et al, 2016; Vernillo et al, 2015; Vernillo et al, 2014).…”

“…We used previously published procedures (Kerhervé, Millet & Solomon, 2015) to alleviate the inaccuracies in GPS-based elevation (Townshend, Worringham & Stewart, 2008). The online utility (GPS Visualizer; ) was used to match the recorded geographical positions (determined by latitude and longitude) to a DEM elevation datum from the National Aeronautics and Space Administration (NASA) Shuttle Radar Topography Mission (SRTM) database.…”

“…Positive pacing (decreasing speed) and a subset of positive pacing including a final end-spurt referred to as parabolic pacing (Abbiss & Laursen, 2008), were observed in UM, such as during a short (45 km) trail UM in recreational runners (Angus & Waterhouse, 2011), a 100 km event on a level, multi-loop course in elite runners (Lambert et al, 2004), a 105 km mountain trail UM in competitive runners (Kerhervé, Millet & Solomon, 2015), and a 161 km mountain trail UM in the five fastest runners over a 28 year period (Hoffman, 2014). Positive pacing has also been observed in other forms of ultra-endurance exercise, such as a 24 h treadmill run (Gimenez et al, 2013), or during an ultra-endurance triathlon event consisting of ten consecutive Ironman distance triathlons (10 × 3.8 km swimming, 180 km cycling, 42 km running) in 10 days (Herbst et al, 2011).…”