Physiological Implication of Slope Gradient during Incremental Running Test

Running Economy in the Vertical Kilometer

New and promising variables are being developed to analyze performance and fatigue in trail running, such as mechanical power, metabolic power, metabolic cost of transport and mechanical efficiency. The aim of this study was to analyze the behavior of these variables during a real vertical kilometer field test. Fifteen trained trail runners, eleven men (from 22 to 38 years old) and four women (from 19 to 35 years old) performed a vertical kilometer with a length of 4.64 km and 835 m positive slope. During the entire race, the runners were equipped with portable gas analyzers (Cosmed K5) to assess their cardiorespiratory and metabolic responses breath by breath. Significant differences were found between top-level runners versus low-level runners in the mean values of the variables of mechanical power, metabolic power and velocity. A repeated-measures ANOVA showed significant differences between the sections, the incline and the interactions between all the analyzed variables, in addition to differences depending on the level of the runner. The variable of mechanical power can be statistically significantly predicted from metabolic power and vertical net metabolic COT. An algebraic expression was obtained to calculate the value of metabolic power. Integrating the variables of mechanical power, vertical velocity and metabolic power into phone apps and smartwatches is a new opportunity to improve performance monitoring in trail running.

Power Is More Relevant Than Ascensional Speed to Determine Metabolic Demand at Different Gradient Slopes During Running

ABSTRACT

Hingrand, C, Olivier, N, Combes, A, Bensaid, S, and Daussin, FN. Power is more relevant than ascensional speed to determine metabolic demand at different gradient slopes during running. J Strength Cond Res 37(11): 2298-2301, 2023-Trail running is characterized by successive uphill and downhill running sessions. To prescribe training intensity, an assessment of maximal running capacity is required. This study compared 2 uphill incremental tests using the same ascensional speed increment to identify the influence of the slope gradient on performance. Ten subjects (8 men and 2 women) performed 3 incremental exercises on various slope (1%: IT01, 10%: IT10, and 25%: IT25), and the ascensional speed increment was similar between IT10 and IT25 (100 m·h-1 every minute). Gas exchanges, heart rate, and power were monitored continuously during the tests. Similar V̇o2max levels were observed in the 3 conditions: 68.7 ± 6.2 for IT01, 70.1 ± 7.3 for IT10, and 67.6 ± 7.0 for IT25. A greater maximal ascensional speed was reached in the IT25 (1760 ± 190 vs. 1,330 ± 106 for IT25 and IT10, respectively, p < 0.01). A significant relationship was observed between relative V̇o2 levels and relative power without any effect of slope. Power should be the parameter used for prescribing training intensity compared with ascensional speed in trail.

Increased oxygen uptake in well-trained runners during uphill high intensity running intervals: A randomized crossover testing

The time spent above 90% of maximal oxygen uptake ( V ˙ O₂max) during high-intensity interval training (HIIT) sessions is intended to be maximized to improve V ˙ O₂max. Since uphill running serves as a promising means to increase metabolic cost, we compared even and moderately inclined running in terms of time ≥90% V ˙ O₂max and its corresponding physiological surrogates. Seventeen well-trained runners (8 females & 9 males; 25.8 ± 6.8yrs; 1.75 ± 0.08m; 63.2 ± 8.4kg; V ˙ O₂max: 63.3 ± 4.2 ml/min/kg) randomly completed both a horizontal (1% incline) and uphill (8% incline) HIIT protocol (4-times 5min, with 90s rest). Mean oxygen uptake ( V ˙ O₂mean), peak oxygen uptake ( V ˙ O₂peak), lactate, heart rate (HR), and perceived exertion (RPE) were measured. Uphill HIIT revealed higher (p ≤ 0.012; partial eta-squared (pes) ≥ 0.351) V ˙ O₂mean (uphill: 3.3 ± 0.6 vs. horizontal: 3.2 ± 0.5 L/min; standardized mean difference (SMD) = 0.15), V ˙ O₂peak (uphill: 4.0 ± 0.7 vs. horizontal: 3.8 ± 0.7 L/min; SMD = 0.19), and accumulated time ≥90% V ˙ O₂max (uphill: 9.1 ± 4.6 vs. horizontal: 6.4 ± 4.0 min; SMD = 0.62) compared to even HIIT. Lactate, HR, and RPE responses did not show mode*time rANOVA interaction effects (p ≥ 0.097; pes ≤0.14). Compared to horizontal HIIT, moderate uphill HIIT revealed higher fractions of V ˙ O₂max at comparable perceived efforts, heartrate and lactate response. Therefore, moderate uphill HiiT notably increased time spent above 90% V ˙ O₂max.

The Energetic Costs of Uphill Locomotion in Trail Running: Physiological Consequences Due to Uphill Locomotion Pattern-A Feasibility Study

The primary aim of our feasibility reporting was to define physiological differences in trail running (TR) athletes due to different uphill locomotion patterns, uphill running versus uphill walking. In this context, a feasibility analysis of TR athletes' cardiopulmonary exercise testing (CPET) data, which were obtained in summer 2020 at the accompanying sports medicine performance center, was performed. Fourteen TR athletes (n = 14, male = 10, female = 4, age: 36.8 ± 8.0 years) were evaluated for specific physiological demands by outdoor CPET during a short uphill TR performance. The obtained data of the participating TR athletes were compared for anthropometric data, CPET parameters, such as V˙Emaximum, V˙O2maximum, maximal breath frequency (BF_max) and peak oxygen pulse as well as energetic demands, i.e., the energy cost of running (C_r). All participating TR athletes showed excellent performance data, whereby across both different uphill locomotion strategies, significant differences were solely revealed for V˙Emaximum (p = 0.033) and time to reach mountain peak (p = 0.008). These results provide new insights and might contribute to a comprehensive understanding of cardiorespiratory consequences to short uphill locomotion strategy in TR athletes and might strengthen further scientific research in this field.

Specific Incremental Test for Aerobic Fitness in Trail Running: IncremenTrail

Trail running (TR) is performed in a natural environment, including various ranges of slopes where maximal oxygen consumption is a major contributor to performance. The aim of this study is to investigate the validity of tests performed in uphill conditions named the "IncremenTrail" (IncT), based on the incremental ascending speed (AS) to evaluate trail runners' cardiorespiratory parameters. IncT protocol included a constant gradient slope set at 25% during the whole test; the starting speed was 500 m·h-1 (25% slope and 2.06 km·h-1) and increased by 100 m·h-1 every minute (0.41 km·h-1). Twenty trail runner specialists performed the IncT and a supramaximal exercise bout to exhaustion with intensity set at 105% of maximal AS (Tlim). Oxygen consumption, breathing frequency, ventilation, respiratory exchange ratio (RER), and heart rate were continuously recorded during the exercises. The blood lactate concentration and rate of perceived exertion were collected at the end of the exercises. During the IncT test, 16 athletes (80%) reached a plateau of maximal oxygen uptake (65.5 ± 7.6 mL·kg-1·min-1), 19 athletes (95%) reached RER values over 1.10 (1.12 ± 0.02) and all the athletes achieved blood lactate concentration over 8.0 mmol·L-1 (17.1 ± 3.5 mmol·L-1) and a maximal heart rate ≥90% of the theoretical maximum (185 ± 11 bpm). Maximal values were not significantly different between IncT and Tlim. In addition, ventilatory thresholds could be determined for all runners with an associated AS. IncT provided a suitable protocol to evaluate trail runners' cardiorespiratory limitations and allowed us to obtain specific intensities based on the ascending speed useful for training purposes in specific conditions.