Abstract
dy aims to evaluate the effects of a 20-week endurance and strength training program on running economy and physiological, spatiotemporal, and neuromuscular variables in trained runners. Methods: A total of 18 runners (13 males and 5 females) completed a running economy test (2 bouts of 5 min at 3.06 m·s −1 for females and at 3.61 m·s −1 for males) and a graded exercise test (5 min at 2.78 m·s −1 , with speed increasing by 0.28 m·s−1 every 1 min until volitional exhaustion). During the training program, the participants completed different low-intensity continuous running sessions, high-intensity interval running sessions, and auxiliary strength training sessions. Results: Running economy, measured as oxygen cost and energy cost, increased by 4% (p= 0.011) and 3.4% (p= 0.011), respectively. Relative maximal oxygen uptake (VO2max) increased by 4.6%. There was an improvement in the speed associated with the first (VT1) and the second ventilatory threshold and with the maximal aerobic speed by 9.4, 3.7,
sessions, and auxiliary strength training sessions. Results: Running economy, measured as oxygen cost and energy cost, increased by 4% (p= 0.011) and 3.4% (p= 0.011), respectively. Relative maximal oxygen uptake (VO2max) increased by 4.6%. There was an improvement in the speed associated with the first (VT1) and the second ventilatory threshold and with the maximal aerobic speed by 9.4, 3.7, and 2.8% (p= 0.000,p= 0.004, andp= 0.004, respectively). The %VO2maxvalue of VT1increased by 4.8% (p= 0.014). Conclusions: These findings suggest that a 20-week endurance and strength training program significantly improves performance and physiological factors without changing the runner’s biomechanics. Keywords:performance; physiology; biomechanics; training; strength 1. Introduction Endurance running performance is influenced by a complex interaction of factors, such as (1) maximal oxygen uptake (VO2max) [1,2], (2) lactate threshold [3,4], (3) second ventilatory threshold [5], and (4) running economy (RE) [6]. Traditionally, VO2maxis considered the best laboratory measure to understand endurance running performance [1]. However, it has been demonstrated that once a minimum VO2maxlevel has been achieved (~70 mL·kg −1 · min −1 ), running performance is mainly determined by RE [7]. RE is the steady-state oxygen uptake (VO2) required at a given submaximal running intensity and is typically expressed as oxygen or energy cost per distance [8]. An incremental running testing performed until the point of exhaustion also allows for the definition of the different training zones (e.g., intensities lower than the velocity of the aerobic threshold, intensities between the velocity of the aerobic and anaerobic threshold, intensities between the velocity of the anaerobic threshold, and the velocity of VO2maxand intensities higher than the Appl. Sci.2025,15, 903 https://doi.org/10.3390/app15020903
Appl. Sci.2025,15, 903 2 of 11 velocity of VO2max) [9]. The ventilatory anaerobic threshold is defined as the exercise intensity above which there is a disproportionate increase in ventilation relative to oxygen consumption [5]. Factors such as training, environment, physiology, biomechanics, and anthropom- etry influence RE [6]. RE can be altered acutely with footwear modifications [10,11] or chronically through training adaptations (physiological and biomechanical factors) [7,12]. Kinematics [13] and kinetics parameters [7] can also impact RE. Thus, more efficient me- chanics lead to less energy wastage [14] by using the muscles’ ability to store and release elastic energy. In this way, a lower vertical displacement and higher vertical and leg stiffness (K leg) have shown significant associations with better RE [15]. Previous research has suggested that different training strategies may influence RE and running performance [16] due to improved muscle work and optimization of running gait [17]. Similarly, strength training has shown performance improvements related to a better RE [18]. This is due to enhanced intramuscular coordination of the lower limbs and an increase in muscle coactivation and K leg[19]. Medium-load (60–85% 1RM) and high-load (>85% 1RM) strength exercises and plyometric exercises carried out 2–3 times per week appear to be efficient in enhancing RE [18]. Similarly, endurance training improves the functionality of skeletal muscle mitochondria and hematological changes [6] with mainly two endurance training strategies, interval and continuous training methods [20]. The influence of these two endurance training methods has usually been studied in isolation in the literature [20]. However, few studies have analyzed the changes in RE following a combined strength and endurance training program. Rodriguez-Barbero et al. [21] showed an improvement of around 5% in RE in recreational and well-trained runners after 8 weeks of a reg- ular endurance training program without changes in spatiotemporal parameters and K leg. However, to our knowledge, no studies have analyzed changes in running per- formance after long-term training. Therefore, this study aimed to evaluate the effects of a20-weekendurance and strength training program on RE and physiological, spa- tiotemporal, and neuromuscular variables in nationally trained long-distance runners. We hypothesized that runners
ular endurance training program without changes in spatiotemporal parameters and K leg. However, to our knowledge, no studies have analyzed changes in running per- formance after long-term training. Therefore, this study aimed to evaluate the effects of a20-weekendurance and strength training program on RE and physiological, spa- tiotemporal, and neuromuscular variables in nationally trained long-distance runners. We hypothesized that runners would improve their RE although without significantly modifying their biomechanics. 2. Materials and Methods 2.1. Participants A total of 18 nationally trained runners, 13 males and 5 females (age:25.56±5.20 years; body mass: 58.70±5.45 kg; height: 170.24±7.93 cm; years of experience in national events: 5.71±1.82; performance: 33:41±04:21 min:ss in 10 km; World Athletics score: 831.89±149.26 points) were recruited for this study. Participants met the following inclu- sion criteria: running at least three days per week without injuries during the previous three months before the study, and faster times <35 and 40 min in 10 km for males and females, respectively. Following the guidelines of McKay et al. [22] the participants were classified asnationally trainedrunners. Before the study, all participants were informed about the testing protocols and the possible risks involved. They provided written informed consent. The study was performed according to the principles of the Declaration of Helsinki (December 2013, Brazil) and the experimental protocols were approved by the ethics committee of the local university (CEIC926).
Appl. Sci.2025,15, 903 3 of 11 2.2. Experimental Design A pre-test–post-test design was used to assess the effects of a 20-week endurance and strength training program. Participants were instructed to avoid strenuous exercise (no intense exercise in the previous 48 h) and caffeine and alcohol intake 24 h before each visit. Participants were tested at the same time and asked to replicate their nutrition, sleep, and training patterns before each session. All data collection was performed at the same time of day and under similar environmental conditions (529 m altitude, 20–25 ◦ C, and 35–40% relative humidity). Furthermore, each participant used the same footwear model in the two visits to control the effect of shoe mass and footwear properties. 2.3. Procedure First, height was measured to the nearest 0.1 cm, and body mass was assessed to the nearest 0.1 kg with a portable stadiometer and caliber (Seca, Bonn, Germany). Then, all participants completed a warm-up that consisted of a 10 min run at a self-selected pace on a treadmill (HP Cosmos Pulsar, H/P/Cosmos Sports & Medical GMBH, Nussdorf-Traunstein, Germany) without stretching or mobility exercises. Subsequently, all participants completed the RE test consisting of 2 bouts of 5 min running at 3.06 m·s −1 for females and 3.61 m·s −1 for males, separated by 2 min of passive recovery (standing quietly on the treadmill) [7]. To obtain further confirmations about VO2values at steady-state, respiratory exchange ratio (RER) values were measured, which were below 1.0 for all participants (0.85±0.04). The treadmill slope was kept at 1% to most accurately reflect the energetic cost of outdoor running [23]. Then, all participants completed the grade exercise test. The test started at 2.78 m·s −1 for 5 min, and the speed increased by 0.28 m·s −1 every 1 min until volitional exhaustion. 2.4. Measurements During the test, respiratory variables were measured using a gas analyzer (CPX Ultima Series MedGraphics, St. Paul, MN, USA) calibrated before each session (CO24.10%; O2 15.92%), with an intra-session variability lower than 0.5%. RE was measured as the energy cost of running (kJ·kg −1 · km −1 ), with the average
−1 every 1 min until volitional exhaustion. 2.4. Measurements During the test, respiratory variables were measured using a gas analyzer (CPX Ultima Series MedGraphics, St. Paul, MN, USA) calibrated before each session (CO24.10%; O2 15.92%), with an intra-session variability lower than 0.5%. RE was measured as the energy cost of running (kJ·kg −1 · km −1 ), with the average respiratory exchange ratio (RER) during the same period and VO2caloric equivalent (kcal/L O2 −1 ) used in previous research [8]. The equation used was the following Lusk [24]: VO2·caloric equivalent·s −1 ·body mass −1 ·K where VO2is measured in liters per minute, caloric equivalent is measured in kilojoules per liter, speed (s) is measured in meters per minute, body mass is measured in kilograms, and distance (K) is 1000 meters. Also, RE was expressed in terms of oxygen cost required at a given submaximal running intensity (mL·kg −1 ·min −1 ). In the grade exercise test (GXT), the average VO2value obtained during the last 30 s of the final running stage was considered as VO2maxwhen at least two of the following criteria were fulfilled [25]: (1) a plateau in VO2(an increase of less than 1.5 mL·kg −1 · min −1 in two consecutive intensities); (2) RER > 1.10; (3) maximal heart rate values above 90% of the age-predicted maximum (220-age); and (4) indication of maximal exhaustion by the athlete. The speed of the final running stage where VO2maxoccurred was the considered maximal aerobic speed (MAS). The first ventilatory threshold (VT1) was identified by an increase in VE/VO2with no concurrent increase in VE/VCO2and a departure from the linearity of ventilation. The second ventilatory threshold (VT2) was identified by a non-linear increase in the VE/VCO2curve concomitant to a second strong increase in VE/VO2, with a further increase in exercise intensity [26].
Appl. Sci.2025,15, 903 4 of 11 The spatiotemporal parameters of the gait cycle [contact time (CT), step frequency (SF), step length (SL), flight time (FT), K leg, and vertical oscillation] were measured for each step during both tests using an inertial measurement unit (Stryd Power Meter, Stryd Inc., Boulder, CO, USA) with a sampling frequency of 1000 Hz. The Stryd Power Meter device has shown adequate validity and reliability compared to optical measurement devices and slow-motion recording to measure spatiotemporal parameters [27] and K leg[28]. For the data analysis, spatiotemporal data were taken from the RE tests, and the velocity of VO2max of the pre-test and the same velocity of the post-test. 2.5. Training Characteristics Twenty weeks (October 2023 to March 2024) of regular endurance running training combined with strength training were retrospectively analyzed for all participants (Figure). The participants were part of a local running club and shared the same coach. Training sessions lasted between 60 and 90 min. They included continuous running at moderate- intensity sessions (zone 1, around 60% of MAS), high-intensity interval sessions (zones 2 and 3, between 80–110% of the maximum aerobic speed [MAS]), and isolated strength training sessions with medium loads (50–70% of one repetition maximum [1RM]), in combination with core exercises, plyometrics, and 50–100 m sprint repetitions. Strength training was aimed at improving trunk strength-endurance capacity with low-intensity, high-volume exercises, along with the development of abilities related to the stretch-shortening cycle with plyometric exercises and leg muscle hypertrophy and strength with isolated strength exercises. Participants followed a pyramidal training intensity distribution characterized by a decreasing training volume from z1 to z2 and z3, respectively. Approximately 80% of the volume was conducted in z1, with the remaining 20% in z2 and z3 [29]. Two training microcycles and a strength session are shown in Table program, participants tracked a significant portion of the training sessions using platforms such as Garmin and/or Strava to monitor the training load accurately. No athlete had to withdraw from the study due to injury.Appl. Sci. 2025, 15, x FOR PEER REVIEW 5 of 11 Figure 1. Endurance training intensity distribution
training microcycles and a strength session are shown in Table program, participants tracked a significant portion of the training sessions using platforms such as Garmin and/or Strava to monitor the training load accurately. No athlete had to withdraw from the study due to injury.Appl. Sci. 2025, 15, x FOR PEER REVIEW 5 of 11 Figure 1. Endurance training intensity distribution for the 20 weeks of training. 2.6. Statistical Analysis Data were represented as mean ± SD. Data were screened for normality using a Shapiro–Wilk test. Paired t-tests were used to analyze the pre–post differences produced in the physiological and spatiotemporal variables before and after the 20 weeks. Effect sizes (ESs) were measured using Cohen’s d, and values of 0.2, 0.5, and above 0.8 were considered small, medium, and large, respectively [30]. The level of significance used was p < 0.05. SPSS 29.0 (SPSS Inc., Chicago, IL, USA) was used for the data analysis. 3. Results The results from the physiological, spatiotemporal, and neuromuscular variables of the RE tests are presented in Table 2. There were significant differences (p < 0.05) between time points (pre–post) in RE (expressed as oxygen cost [OC] and energy cost [EC]). How- ever, there were no significant differences in spatiotemporal and neuromuscular variables during the RE test. OC and EC were significantly higher in the post-test (43.55 ± 3.23 vs. 45.36 ± 3.18 mL·kg −1 ·min −1 and 4.28 ± 0.25 vs. 4.43 ± 0.21 kJ·kg −1 ·km −1 , respectively). Table 2. Results of physiological, spatiotemporal, and neuromuscular variables of the RE test. Variables Time Points Paired t-Test Pre Post ES p OC (mL·kg −1·min −1) 43.55 ± 3.23 45.36 ± 3.18 0.677 0.011 EC (kJ/kg/km) 4.28 ± 0.25 4.43 ± 0.21 0.672 0.011 CT (s) 0.229 ± 0.015 0.229 ± 0.016 0.051 0.830 FT (s) 0.136 ± 0.019 0.135 ± 0.017 0.078 0.746 SF (step/min) 164.64 ± 5.90 165.22 ± 5.45 0.144 0.549 SL (m) 1.27 ± 0.11 1.26 ± 0.10 0.156 0.517 K leg (kN·m −1) 8.99 ± 1.38 9.01 ± 1.30 0.020 0.934 Vertical oscillation (cm) 8.62 ± 0.97 8.81 ± 0.81
(s) 0.229 ± 0.015 0.229 ± 0.016 0.051 0.830 FT (s) 0.136 ± 0.019 0.135 ± 0.017 0.078 0.746 SF (step/min) 164.64 ± 5.90 165.22 ± 5.45 0.144 0.549 SL (m) 1.27 ± 0.11 1.26 ± 0.10 0.156 0.517 K leg (kN·m −1) 8.99 ± 1.38 9.01 ± 1.30 0.020 0.934 Vertical oscillation (cm) 8.62 ± 0.97 8.81 ± 0.81 0.332 0.177 Data are presented as mean ± standard deviation. OC, oxygen cost; EC, energy cost; CT, contact time; FT, flight time; SF, step frequency; SL, step length; K leg, leg stiffness. Figure 1.Endurance training intensity distribution for the 20 weeks of training.
Appl. Sci.2025,15, 903 5 of 11 Table 1.Example of two types microcycles and a strength session of the participants. Monday Tuesday Wednesday Thursday Friday Saturday Sunday Week3 Type of session Continuous running High- intensity interval Continuous running Strength High- intensity interval Continuous running Continuous running Volume 60 min 55 min 70 min 50 min 70 min 80 min 80 min 12–14 km 10–12 km 14–16 km 12–14 km 15–17 km 15–17 km Intensity 60% MAS 105% MAS 65% MAS 55% RM 90% MAS 60% MAS 65% MAS Examples of high-intensity interval sessions 3×(6×400 m + 1000 m) with 1 and 2 min of passive recovery 2×16 min threshold training with 2 min of passive recovery 15×400 m with 75 s of passive recovery Week 18 Type of session Continuous running High- intensity interval Continuous running + technique High- intensity interval Strength Continuous running Volume 60 min 70 min 50 min 80 min 50 min 90 min 10–12 km 12–15 km 8–10 km 14–16 km 18–20 km Intensity 60% MAS 105% MAS 60% MAS 90% MAS 65% RM 65% MAS Examples of high-intensity interval sessions 12×500 m with 2 min of passive recovery 8×5 min threshold training with 2 min of passive recovery 16 min threshold training + 8×400 m with 2 and 1 min and 30 s of passive recovery Strength session Strength exercises 4 bouts of 6 repetitions at 60% of 1RM with 1 min recovery Unipodal dead weight Bulgarian squat Charged Hip thrust Squat Gluteal bridge Core exercises 4 bouts of 12 repetitions Dead bug Mountain climbers Crunches Plank Leg raises Plyometrics exercises 4 bouts of 5 repetitionsBox jumps Drop jumps Vertical jumps Strides Sprint 8 repetitions of 100 m at maximum speed with 1 min recovery 2.6. Statistical Analysis Data were represented as mean±SD. Data were screened for normality using a Shapiro–Wilk test. Paired t-tests were used to analyze the pre–post differences produced in the physiological and spatiotemporal variables before and after the 20 weeks. Effect sizes (ESs) were measured using Cohen’s d, and values of 0.2, 0.5, and above 0.8 were considered small, medium, and large,
Statistical Analysis Data were represented as mean±SD. Data were screened for normality using a Shapiro–Wilk test. Paired t-tests were used to analyze the pre–post differences produced in the physiological and spatiotemporal variables before and after the 20 weeks. Effect sizes (ESs) were measured using Cohen’s d, and values of 0.2, 0.5, and above 0.8 were considered small, medium, and large, respectively [30]. The level of significance used wasp< 0.05. SPSS 29.0 (SPSS Inc., Chicago, IL, USA) was used for the data analysis. 3. Results The results from the physiological, spatiotemporal, and neuromuscular variables of the RE tests are presented in Table. There were significant differences ( p< 0.05) between time points (pre–post) in RE (expressed as oxygen cost [OC] and energy cost [EC]). How- ever, there were no significant differences in spatiotemporal and neuromuscular variables during the RE test. OC and EC were significantly higher in the post-test (43.55±3.23 vs. 45.36±3.18 mL·kg −1 ·min −1 and 4.28±0.25 vs. 4.43±0.21 kJ·kg −1 ·km −1 , respectively).
Appl. Sci.2025,15, 903 6 of 11 Table 2.Results of physiological, spatiotemporal, and neuromuscular variables of the RE test. Variables Time Points Pairedt-Test Pre Post ES p OC (mL·kg −1 ·min −1 ) 43.55±3.23 45.36 ±3.18 0.677 0.011 EC (kJ/kg/km) 4.28±0.25 4.43 ±0.21 0.672 0.011 CT (s) 0.229±0.015 0.229 ±0.016 0.051 0.830 FT (s) 0.136±0.019 0.135 ±0.017 0.078 0.746 SF (step/min) 164.64±5.90 165.22 ±5.45 0.144 0.549 SL (m) 1.27±0.11 1.26 ±0.10 0.156 0.517 K leg(kN·m −1 ) 8.99±1.38 9.01 ±1.30 0.020 0.934 Vertical oscillation (cm)8.62±0.97 8.81 ±0.81 0.332 0.177 Data are presented as mean±standard deviation. OC, oxygen cost; EC, energy cost; CT, contact time; FT, flight time; SF, step frequency; SL, step length; K leg, leg stiffness. The results from the physiological, spatiotemporal, and neuromuscular variables dur- ing the GXT are shown in Table. There were significant differences ( p< 0.05) between time points (pre–post) in the speed of VT1, VT2, and MAS, in the oxygen cost of VT1and VT2, in the relative VO2max, and in the percentage of VT1. There was a significantly higher speed of VT1(13.44±1.65 vs. 14.67±1.61 km·h −1 ), VT2(17.94±1.86 vs.18.61±1.72 km·h −1 ), and MAS (19.44±2.09 vs. 20.00±2.03 km·h −1 ) in the post-test compared to the pre-test. The oxygen cost of VT1(46.69±6.29 vs. 51.38±4.83 mL·kg −1 · min −1 ) and VT2(58.83±8.13 vs. 62.53±6.61 mL·kg −1 · min −1 ) significantly increased in the post-test. The relative VO2max was significantly higher (61.55±8.77 vs. 64.53±7.00 mL·kg −1 · min −1 ) in the post-test. The percentage of VT1significantly increased (76.06±3.95 vs.79.90±5.28%) in the post- test (Figure). However, there were no significant differences in the spatiotemporal and neuromuscular variables during the GXT. Table 3.Results of physiological, spatiotemporal, and neuromuscular variables of the GXT test. Variables Time Points Pairedt-Test Pre Post ES p VT 1speed (km·h −1 ) 13.44±1.65 14.67 ±1.61 1.296 <0.001 VT 2speed (km·h −1 ) 17.94±1.86 18.61 ±1.72 0.778 0.004 Maximal aerobic speed (km·h −1 ) 19.44±2.09 20.00 ±2.03 0.788 0.004 Oxygen cost of VT 1 (mL·kg −1 ·min −1 ) 46.69±6.29 51.38 ±4.83 1.089 <0.001 Oxygen cost of VT 2 (mL·kg −1 ·min −1
Description
This study evaluates the impact of a 20-week training program on running performance.