Abstract
ound: This study aimed to provide reference values for estimating training intensities in long-distance runners based on progressive incremental tests, considering differences related to sex and performance level. Methods: A total of 1411 endurance-trained runners (819 men and 592 women) completed a standardized treadmill protocol with gas exchange analysis to determine ventilatory thresholds and peak oxygen consumption (VO 2peak). Heart rate (HR) and running speed at each threshold were expressed relative to their peak values. Results: HR at second ventilatory threshold (VT2) occurred at 93.5±2.5% of HR peak, and HR at first ventilatory threshold at 85.1±4.6%. The relative running speeds at VT2 and VT1 corresponded to 87.6±3.9% and 73.9±5.5% of the speed at VO 2peak, respectively. In men, beginners exhibited higher relative HR and VO2values at the ventilatory thresholds than elite runners. In contrast, women displayed higher and more stable relative values across performance levels. Conclusions: These findings establish precise, evidence-based reference ranges derived from a large cohort of runners and highlight the need to consider sex and performance level when estimating exercise intensities. Individualized physiological assessment remains essential for accurate training prescription and performance optimization. Keywords:endurance training; performance analysis; heart rate; VT1; VT2; running speed; oxygen consumption 1. Introduction Exercise intensity is one of the key external load variables used to modulate the exercise dose administered to an
runners and highlight the need to consider sex and performance level when estimating exercise intensities. Individualized physiological assessment remains essential for accurate training prescription and performance optimization. Keywords:endurance training; performance analysis; heart rate; VT1; VT2; running speed; oxygen consumption 1. Introduction Exercise intensity is one of the key external load variables used to modulate the exercise dose administered to an athlete, together with exercise type, duration, and recovery [1]. Having effective strategies to control exercise intensity of each session is essential for the proper execution of the training plan and the enhancement of athletic performance [2]. Several variables can help determine the actual toughness of exercise and the level of physiological demand it imposes on the athlete. In the case of endurance runners, oxygen consumption and blood lactate concentration are considered the most valid and commonly used indicators in scientific research [3]. However, during regular training sessions, more practical measures such as running speed, rate of perceived exertion, and heart rate (HR) are typically preferred [4]. Associating these variables with specific physiological milestones can facilitate targeted work on the physiological determinants of performance at any given moment, especially those related to maximal oxygen consumption (VO2max) and the Sports2026,14, 29 https://doi.org/10.3390/sports14010029
Sports2026,14, 29 2 of 14 ventilatory thresholds, ventilatory threshold 1 (VT1) and ventilatory threshold 2 (VT2) [5]. In this context, training zones provide a useful framework for defining specific intensity ranges—commonly based on running speed or HR—within which the desired training stimulus can be precisely applied [2]. To achieve this, it is essential that training zone calculations are based on direct testing, preferably involving gas exchange analysis or blood lactate measurement, using methodologies validated by the scientific literature [6]. However, it is often difficult for athletes and coaches to access the equipment and infrastructure required to perform these tests, which forces them to estimate training zones indirectly. Some of the most used methods are based on single-effort prediction trials [7], maximal HR, or the HR corresponding to the metabolic thresholds, among others [2]. From these reference values, percentage-based estimations can be applied to predict HR or speed at other physiological landmarks or to prescribe exercise intensities [8]. Several studies have demonstrated the accuracy of fixed-intensity anchors (e.g., specific percentages of maximal HR, VO2max, or maximal aerobic speed) for estimating VT2 and VT1 in runners [9–11]. Nevertheless, other studies suggest that these percentage values can vary considerably between individuals, with factors such as sex and training status potentially influencing these estimations [12–14]. Specifically, sex is an important factor to consider when attempting to individualize training zones. Traditionally, women’s training programs have been established following the same standards as those of men, despite the fact that physiological responses to exercise differ between the sexes [15]. Considering sex-specific responses is therefore essential not only for optimizing training outcomes but also for accurately interpreting performance and physiological testing data. In addition, it should be noted that in progressive incremental tests to exhaustion, lower-level athletes may not always reach their VO2max, possibly due to a lower physiolog- ical resilience or tolerance to high-intensity effort [16,17]. This limitation can introduce bias when defining maximal reference values, particularly when these are later used to estimate training zones or metabolic thresholds indirectly. On the other hand, in recent years, there has been a considerable increase in the use
may not always reach their VO2max, possibly due to a lower physiolog- ical resilience or tolerance to high-intensity effort [16,17]. This limitation can introduce bias when defining maximal reference values, particularly when these are later used to estimate training zones or metabolic thresholds indirectly. On the other hand, in recent years, there has been a considerable increase in the use of training monitoring platforms and wearable devices among both recreational and trained runners [18]. These platforms often include automated tools for calculating training zones; however, these zones are frequently too generic and fail to account for individual variables that can significantly influence their accuracy and applicability [18]. Therefore, having reference values derived from direct measurements in a large cohort of runners— including various performance levels and both sexes—may help coaches and athletes with limited access to laboratory testing to more accurately determine their training zones using progressive exercise tests performed to volitional exhaustion. Thus, the aim of the present study was to analyze and present absolute and relative data for running speed, HR, and oxygen consumption (VO2) with respect to their maximal values at VT1 and VT2 in trained long-distance runners of different performance levels (from recreational to elite) and of both sexes, obtained from a progressive incremental performance test performed until exhaustion. In this way, percentage reference values can be established for the different metabolic milestones. The hypotheses proposed based on previous scientific literature were as follows: (1) Female runners will present higher relative HR values (as a percentage of maximum) at VT1 and VT2 compared with male runners. (2) Female runners will present higher relative running speed values (as a percentage of maximal speed reached at the test) at VT1 and VT2 compared with male runners. (3) The lower ability to sustain high-intensity efforts in lower-performance athletes will result in higher relative running speed and HR values (as a percentage of maximal aerobic speed and HR peak value) at VT1 and VT2 compared with higher-performance athletes. https://doi.org/10.3390/sports14010029
lower ability to sustain high-intensity efforts in lower-performance athletes will result in higher relative running speed and HR values (as a percentage of maximal aerobic speed and HR peak value) at VT1 and VT2 compared with higher-performance athletes. https://doi.org/10.3390/sports14010029
Sports2026,14, 29 3 of 14 2. Materials and Methods 2.1. Participants A total of 1411 athletes participated in the study, comprising 819 men (173.8±7.4 cm, 74.4±10.7 kg, and 37.1±12.4 years) and 592 women (162.3±6.6 cm, 60.0±9.5 kg, and 37.0±11.8 years). All participants were habitual runners with a minimum of one year of experience in structured endurance training. Participants were required to perform a minimum of three running training sessions per week. The athletes were recruited from two training groups specifically dedicated to distance running training and competition. The athletes voluntarily completed the performance tests between 2021 and 2025. All tests were conducted between the 2nd and 5th week of training in each season. The test was conducted after a period of reduced training between competitive seasons (2 to 3 weeks), during the early preparatory phase. All participants provided their informed consent prior to the use of their data in this research. The study procedures were reviewed and approved by the Ethics Committee of the University of Alicante (protocol code: A-2017-04-11 expedient). All data collection procedures adhered to the principles outlined in the Declaration of Helsinki. 2.2. Procedures The running performance test was performed on a treadmill (Woodway PRO XL, Waukesha, WI, USA). All tests were conducted in the morning (08:00–11:00 h). Participants were instructed to avoid strenuous exercise for 24 h prior to testing. The protocol started at a 1% gradient, with increments of 0.3 km·h −1 every 30 s until volitional exhaustion [19]. The initial speed was individually determined to ensure that the total test duration ranged between 10 and 15 min and did not exceed 26 min [20]. A portable gas exchange analyzer (Cosmed K5, Rome, Italy) was used to determine ventilatory thresholds and the peak value of VO2(VO 2peak). The recorded respiratory variables included VO2, pulmonary ventilation (VE), ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), and end-tidal partial pressures of oxygen (PETO2) and carbon dioxide (PETCO2). VO 2peakwas defined as the highest 1-min average VO2value obtained during the test. VT1 and VT2 were determined according to the criteria described by Davis et al. [21]. VT1
VO2(VO 2peak). The recorded respiratory variables included VO2, pulmonary ventilation (VE), ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), and end-tidal partial pressures of oxygen (PETO2) and carbon dioxide (PETCO2). VO 2peakwas defined as the highest 1-min average VO2value obtained during the test. VT1 and VT2 were determined according to the criteria described by Davis et al. [21]. VT1 was identified by a systematic increase in both VE/VO2and PETO2without a concomitant rise in VE/VCO2, whereas VT2 was defined by a simultaneous increase in VE/VO2and VE/VCO2accompanied by a decline in PETCO2. Both VT1 and VT2 were independently assessed by three experienced evaluators. Other data were collected during the test in- cluding voluntary exhaustion of the participant, HR≥theoretical HRmax (calculated as 208–0.7·age [22]). The corresponding running speed at VO 2peak(SVO 2peak) and at VT1 (SVT1) and VT2 (SVT2) was recorded. Additionally, running economy (RE) was assessed following the warm-up. Partici- pants performed a 6-min constant-speed run at an intensity corresponding to their estimated VT1, determined from recent training sessions. VO2was continuously measured through- out the test, and the mean VO2from the final 3 min was used for the calculation. Running economy, expressed as mL·kg −1 ·km −1 , was calculated using the equation: (60 divided by the running speed in km·h −1 ) multiplied by the average VO2value in mL·kg −1 · min −1 . Furthermore, the relative VO2at VT2 and VT1 was calculated as a percentage of VO2max. HR was continuously monitored throughout the test using a telemetry-based system (Polar Verity Sense, Polar Electro, Kempele, Finland). The peak heart rate value (HR peak) was defined as the highest value recorded during the test. In addition, HR values were asso- ciated with the HR corresponding to VT2 (HRVT2) and VT1 (HRVT1). The relative HR as a percentage of the HR peakat VT2 and VT1 was calculated. Also, the relative HR as https://doi.org/10.3390/sports14010029
Sports2026,14, 29 4 of 14 a percentage of HRVT2 at HR peakand VT1 was calculated. Finally, the relative running speeds at VT1 and VT2 were calculated as percentages of both SVO 2peakand the speed corresponding to VT2. For the subsequent analysis, athletes were categorized according to their per- formance level based on their VO 2peakvalues. The classification criteria proposed by Barnes and Kilding [23] were used to define the performance groups as follows: Very high aerobic fitness (elite) men > 75.4 mL·kg −1 · min −1 ; High aerobic fitness men 70.8–75.4 mL·kg −1 ·min −1 ; moderately aerobic fitness men 62.2–70.0 mL·kg −1 · min −1 ; low to moderate aerobic fitness men 54.2–62.2 mL·kg −1 · min −1 ; and low aerobic fitness (beginners) men < 54.2 mL·kg −1 · min −1 . For women, very high aerobic fitness (elite) women> 66.2 mL·kg −1 ·min −1 ; High aerobic fitness women 61.7–66.2 mL·kg −1 · min −1 ; moderately aerobic fitness women 55.8–61.7 mL·kg −1 · min −1 ; low to moderate aerobic fitness women 49.7–55.8 mL·kg −1 · min −1 ; and low aerobic fitness (beginners) women < 49.7 mL·kg −1 ·min −1 . 2.3. Data Analysis A descriptive analysis was conducted using the mean and standard deviation (SD) of all variables under study. An independent samples t-test was performed to analyse potential differences in the recorded variables according to performance level and sex. For comparisons involving the very high aerobic fitness males, very high aerobic fitness females, and high aerobic fitness female groups, the nonparametric Mann–Whitney U test was used to detect statistical differences between variables. Pearson’s bivariate correlation coefficient was used to determine the existence of any inter-relationships between the measured variables. Effect size was calculated using Cohen’s d [24] interpreted as follows: trivial (0–|0.2|), small (|0.2|–|0.4|), moderate (|0.4|–|0.8|), and large (>0.8) [25]. Prior to the analyses, the normality of the data was verified using the Kolmogorov–Smirnov (KS) test, confirming a normal distribution. Homogeneity of variances was assessed with Levene’s test. All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS,
calculated using Cohen’s d [24] interpreted as follows: trivial (0–|0.2|), small (|0.2|–|0.4|), moderate (|0.4|–|0.8|), and large (>0.8) [25]. Prior to the analyses, the normality of the data was verified using the Kolmogorov–Smirnov (KS) test, confirming a normal distribution. Homogeneity of variances was assessed with Levene’s test. All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS, version 22.0; IBM Corp., Chicago, IL, USA). Statistical significance was set atp< 0.05. 3. Results Table Higher running speeds at VT1 and VT2 and at VO 2peakwere observed in higher-level athletes for both men and women. Better running RE values were recorded in the higher- level runners of both sexes. Additionally, lower percentages of VO2relative to VO 2peak at VT1 and VT2 were evident in higher-level male athletes, whereas no such trend was observed in female athletes. The percentage of participants reaching the theoretical maximal HR were higher in athletes of greater performance level. Overall, these differences were more pronounced in men than in women. In addition, the number of years of training and competitive experience can be observed in the dataset and descriptively shows that the groups with higher physiological performance presented a greater number of years of both training and competitive experience. https://doi.org/10.3390/sports14010029
Sports2026,14, 29 5 of 14 Table 1.Physiological variables obtained from the performance tests according to performance level and sex. Very High Aerobic Fitness High Aerobic Fitness Moderately Aerobic Fitness Low to Moderate Aerobic Fitness Low Aerobic Fitness Male n = 22 n = 35 n = 156 n = 258 n = 348 VO 2peak(mL·kg −1 ·min −1 ) 79.2±4.4 72.8 ±1.3 65.9 ±2.5 57.8 ±2.2 46.6 ±5.5 Years of experience (n) 9.7 ±1.6 8.1 ±2.6 6.1 ±2.5 4.2 ±2.0 3.1 ±1.7 SVO 2peak(km/h) 22.0 ±1.1 20.9 ±1.4 18.6 ±1.9 16.4 ±1.4 14.0 ±1.8 Economy (mL·kg −1 · min −1 ) 194.5±16.4 199.0 ±22.6 207.1 ±27.2 218.0 ±25.2 219.7 ±25.8 SVT2 (km/h) 19.2 ±0.6 18.1 ±1.4 16.1 ±1.7 14.2 ±1.4 12.1 ±1.6 SVT1 (km/h) 15.5 ±0.7 15.3 ±1.0 13.6 ±1.3 11.9 ±1.2 10.2 ±1.5 %VO 2peakVT2 (%) 83.8 ±5.1 85.1 ±4.8 85.9 ±5.6 87.1 ±5.9 87.4 ±5.3 %VO 2peakVT1 (%) 67.5 ±5.9 69.1 ±6.4 70.1 ±8.5 73.2 ±6.9 73.4 ±8.3 THRmax (%) 83.6 77.4 73.1 65.3 63.2 Female n = 6 n = 16 n = 56 n = 105 n = 409 VO2max(mL·kg −1 ·min −1 ) 68.4±1.8 63.3 ±1.4 58.0 ±1.7 52.4 ±1.7 40.9 ±6.1 Years of experience (n) 8.2 ±1.3 7.3 ±2.4 5.4 ±2.3 3.8 ±1.7 2.6 ±1.4 Economy (mL·kg −1 · min −1 ) 203.4±23.6 204.5 ±24.9 215.2 ±23.8 225.9 ±25.3 223.6 ±24.9 SVO 2peak(km/h) 17.7 ±0.6 17.7 ±1.2 16.3 ±1.2 14.5 ±1.3 12.2 ±1.9 SVT2 (km/h) 15.8 ±0.4 15.6 ±0.9 14.4 ±0.9 12.9 ±1.1 10.7 ±1.7 SVT1 (km/h) 13.6 ±0.5 13.3 ±0.9 12.6 ±1.0 11.1 ±1.2 9.1 ±1.6 %VO 2peakVT2 84.5 ±5.6 88.4 ±3.6 89.0 ±4.9 88.0 ±5.4 88.1 ±6.9 %VO 2peakVT1 69.2 ±7.5 72.7 ±5.3 77.3 ±7.0 75.3 ±7.7 75.1 ±9.3 THRmax (%) 83.3 81.3 74.4 71.1 71.9 Note: VO 2peak= Peak value of oxygen consumption; mL = millilitres; Kg = kilograms; min = minute; SVO 2peak= Speed corresponding to peak oxygen consumption; km = kilometre; h = Hour; SVT2 = Speed corresponding to second ventilatory threshold; SVT1 = Speed corresponding to first ventilatory threshold; %VO 2peakVT2 = Percentage of oxygen consumption relative to
81.3 74.4 71.1 71.9 Note: VO 2peak= Peak value of oxygen consumption; mL = millilitres; Kg = kilograms; min = minute; SVO 2peak= Speed corresponding to peak oxygen consumption; km = kilometre; h = Hour; SVT2 = Speed corresponding to second ventilatory threshold; SVT1 = Speed corresponding to first ventilatory threshold; %VO 2peakVT2 = Percentage of oxygen consumption relative to peak oxygen consumption at second ventilatory threshold; %VO 2peakVT1 = Percentage of oxygen consumption relative to peak oxygen consumption at first ventilatory threshold; VO2maxPlateau = Percentage of the sample that reached the plateau in oxygen consumption; THRmax= Percentage of the sample that reached the theoretical maximum heart rate. Table formance test, along with comparisons between male and female athletes across differ- ent performance levels. Considering the entire sample, the HRVT2 corresponded to 93.5±2.5% of HR peak, while HRVT1 represented 85.1±4.6% of HR peak. Conversely, when taking HRVT2 as a reference point, HR peakcorresponded to 107.0±2.9%, and HRVT1 to 90.9±3.7%. The relative running speed at VT2 with respect to SVO 2peakwas 87.6±3.9%, while the relative speed at VT1 was 73.9±5.5%. When using the running speed at VT2 as the reference, the relative SVO 2peakcorresponded to 114.4±5.3%, and the relative speed at VT1 was 84.4±4.7%. Table 2.Relative heart rate and running speed according to performance level and sex. Global Very High Aerobic Fitness High Aerobic Fitness Moderately Aerobic Fitness Low to Moderate Aerobic Fitness Low Aerobic Fitness Male n = 819 n = 22 n = 35 n = 156 n = 258 n = 348 %HRpeak VT2 (%) 93.0 ±2.5 * 90.8 ±2.1 * 91.9 ±2.4 * 92.7 ±2.5 * 93.0 ±2.5 * 93.4 ±2.4 * VT1(%) 84.2 ±4.7 * 80.5 ±3.9 * 81.8 ±4.7 * 83.3 ±5.2 * 84.5 ±4.2 * 84.8 ±4.6 * %VT2. HR VO 2peak(%) 107.6±2.6 * 110.2±2.6 * 108.7 ±2.9 107.9 ±2.3 * 107.6 ±2.9 * 107.1 ±2.8 * VT1(%) 86.9 ±3.9 * 88.6 ±4.6 88.9 ±3.9 * 89.8 ±3.9 * 90.8 ±3.5 * 90.7 ±3.7 * %SVO 2peak VT2 (%) 86.9 ±3.9 * 86.5 ±3.6 86.7 ±3.7 86.8 ±3.9 * 86.7 ±3.8 * 87.1 ±4.0
* 84.8 ±4.6 * %VT2. HR VO 2peak(%) 107.6±2.6 * 110.2±2.6 * 108.7 ±2.9 107.9 ±2.3 * 107.6 ±2.9 * 107.1 ±2.8 * VT1(%) 86.9 ±3.9 * 88.6 ±4.6 88.9 ±3.9 * 89.8 ±3.9 * 90.8 ±3.5 * 90.7 ±3.7 * %SVO 2peak VT2 (%) 86.9 ±3.9 * 86.5 ±3.6 86.7 ±3.7 86.8 ±3.9 * 86.7 ±3.8 * 87.1 ±4.0 * VT1(%) 73.1 ±5.1 * 72.8 ±3.8 * 73.5 ±3.9 73.1 ±5.0 * 73.2 ±4.7 * 72.9 ±5.6 * %SVT2S VO 2peak(%) 115.3±5.3 * 115.8 ±4.9 115.6 ±5.1 115.4 ±5.4 * 115.6 ±5.2 * 115.0 ±5.4 * VT1 (%) 84.1 ±4.5 * 84.1 ±3.4 * 84.8 ±3.4 84.2 ±4.6 * 84.4 ±4.2 * 83.7 ±4.8 https://doi.org/10.3390/sports14010029
Description
The study establishes reference values for training intensities in long-distance runners.