The aim of the study was to compare the performance effects of the intensity demarcation model based on the race pace based approach with the triphasic physiological model and heart rate variability guidelines (HR+HRV)
After being informed and signing informed consent about the present study, participants were randomly assigned to one of three groups before the intervention phase using a Web-based computer program (www.randomizer.org). Groups were matched on a 1:1:1 basis by gender, age, and performance in an official 10-km race in the previous month. Once selected, participants in the heart rate variability (HRV) group began daily measurements to obtain their personalized parameters. The groups changed according to the intensity zone demarcation pattern: heart rate (HR), race pace (RP) and HR+HRV. The HR group was considered the active control group, as considered the current best practice according to the current literature in endurance running. A 4-week pre-intervention plus 6-week intervention program was set up. Participants were assessed in four different sessions, two for laboratory evaluations and two for time trial performance. The first session consisted of a running economy test, and, after at least half an hour of rest, a maximal incremental treadmill run. They familiarised themselves with the training sessions according to their group (i.e., running based on HR, RP or HR+HRV guidelines, respectively). The HRV4training mobile application (https://www.hrv4training.com) was used to assess HRV for one minute in the morning. The difference in RR intervals between heartbeats is used to calculate HRV. The program then uses this information to calculate the rMSSD and moving average (LnrMSSD7-d), converting the results to a number between 5 and 10. Then, the participant must answer a series of questions including his or her current physical state, sleep quality, muscle soreness, etc. After interpolating these variables, the application shows the subjective value derived from the body's reaction to stresses. As a result, daily indications are given in numerical form, with a range of normality (for HR and HRV) that varies each day depending on how the person reacts to stress. Participants were instructed to take the measurement as soon as they woke up, with an empty bladder, lying down, trying to limit movement, and breathing naturally Training variables (total time, distance, total time spent in each zone) and Training Impulse (TRIMP) were the same for all groups
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
28
Runners ran according to speeds and HR associated with ventilatory thresholds. Z1, zone 1: intensity zone below the first ventilatory threshold; Z2: zone 2, intensity zone between the first and second ventilatory threshold; Z3: zone 3, intensity zone above the second ventilatory threshold.
Runners ran respecting three intensity zones. The average speed achieved in the 7-km was calculated. From this, three intensity zones were calculated, adhering to the % of the race pace of the 7-km test. Z1 corresponds to less than 80% of race pace, Z2 is between 80-95%, and Z3 corresponds to over 95% of race pace
Universidad Rey Juan Carlos
Fuenlabrada, Madrid, Spain
Change from Baseline of Running Economy
Tests were performed on the treadmill and respiratory gas analysis was carried out. The laboratory tests included: \- Running economy (RE) test (ml·kg·km) RE was measured by running two blocks at constant speeds (7 and 9 km·h\^-1 or 8 and 10 km·h\^-1, respectively), depending on the subject's level, intensities below the first ventilatory threshold. Each block lasted three minutes. RE is one of the physiological determinants of endurance performance: an improvement in RE over time indicates an improvement in performance
Time frame: Baseline and after 6 weeks
Change from Baseline of VO2max
Tests were performed on the treadmill and respiratory gas analysis was carried out. The laboratory tests included: \- Maximum oxygen consumption test (VO2max) After 30 minutes of rest, a maximal incremental test was performed to calculate relative VO2max (ml·kg\^-1·min\^-1) and absolute VO2max (L·min\^-1). The test started at the last speed of the RE test (9 or 10 km·h\^-1), depending on the subject's level. The speed increased continuously by 0.5 km·h-1 every minute until exhaustion. The mean value of the last 30 s of the VO2, a respiratory exchange ratio (RER) \>1.05, a HR \> 95% of the maximum HR, and an RPE \> 18 were the variables considered to calculate the VO2max VO2max is one of the determinants of endurance performance. The relative VO2max is influenced by weight (at equal VO2max, the runner who weighs less is more advantaged). An improvement in absolute and relative values of VO2max over time indicate an improvement in performance
Time frame: Baseline and after 6 weeks
Change from Baseline of Maximum aerobic velocity (VAM)
Tests were performed on the treadmill and respiratory gas analysis was carried out. The laboratory tests included: \- Maximum aerobic velocity (VAM) in km·h\^-1 VAM was calculated as the minimum speed that elicits maximum oxygen consumption. VAM is one of the physiological determinants of endurance performance. An increase in VAM velocity over time is an indication of improved performance
Time frame: Baseline and after 6 weeks
Change from Baseline of 7-km Time Trial Performance
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Runners completed training sessions based on HR values and velocities associated with ventilatory thresholds (i.e., Z1, zone 1: intensity zone below the first ventilatory threshold; Z2: zone 2, intensity zone between the first and second ventilatory threshold; Z3: zone 3, intensity zone above the second ventilatory threshold. The training sessions were based on physiological thresholds and daily HRV cues. High-intensity training was performed only under optimal HRV conditions, thus only when each participant had HRV values in their reference range. If HRV was not optimal, low-intensity training was prescribed. If HRV was not optimal for two days consecutively, rest was prescribed.
Before and after 6 weeks, the final time achieved in a 7-km time trial performance was calculated for all participants. The athletes were instructed to achieve their best performance on the 7-km. The test was performed in a 400m regulation athletic track. Verbal encouragement was given to all runners in both tests every 400-m lap. Participants used the same shoe model in the two tests and were asked not to use stimulants (coffee, tea, etc.). They performed the tests at the same time of day ± (2 hours). A decrease in the final time in the second test, indicates an improvement in performance
Time frame: Baseline and after 6 weeks
Change from Baseline of the First Physiological Thresholds (VT1)
Ventilatory thresholds (VT1 and VT2), measured by gas analysis, are some of the determinants of endurance performance, along with running economy and VO2max. Were measured changes in: \- Velocity associated with the first ventilatory threshold (VT1) in km·h\^-1 Velocity zones corresponding to VT1 indicates a low intensity zone. An increase over time in VT1 indicates an improvement of the aerobic system
Time frame: Baseline and after 6 weeks
Change from Baseline of the second Physiological Thresholds (VT2)
Ventilatory thresholds (VT), measured by gas analysis, are some of the determinants of endurance performance, along with running economy and VO2max. Were measured changes in: \- Velocity associated with the second ventilatory threshold (VT2) in km·h\^-1. Intensity zones corresponding to VT2 indicates a high intensity zone. An increase over time in VT2 indicates an improvement in the anaerobic system
Time frame: Baseline and after 6 weeks
Change from baseline in HR associated with the first ventilatory threshold
Ventilatory thresholds (VT), measured by gas analysis, are some of the determinants of endurance performance, along with running economy and VO2max. were measured changes in: \- HR associated with the first ventilatory threshold HR-VT1 in beats per minute (bpm). A lower HR associated with VT1, indicates an improvement of the aerobic system over time
Time frame: Baseline and after 6 weeks
Change from baseline in HR associated with the second ventilatory threshold
Ventilatory thresholds (VT), measured by gas analysis, are some of the determinants of endurance performance, along with running economy and VO2max. were measured changes in: \- HR associated with the second ventilatory threshold (HR-VT12) in beats per minute (bpm). Higher HR associated with VT2, indicates an improvement of the anaerobic system over time
Time frame: Baseline and after 6 weeks
Change of Rate of Perceived Exertion (RPE) scale after 6 weeks protocol
Participants indicated Rating of perceived exertion (RPE) using Borg's 6-20 validated scale, an exertion perception scale used during laboratory testing. RPE values were measured for both the running economy and during the incremental maximal test (VO2max). The RPE values are: 6\. = no exertion at all 7. = extremely light 9. = very light 11. = light 13. = somewhat hard 15. = hard (heavy) 17. = very hard 19. = extremely hard A decrease in RPE over time for the same intensity (e.g., same speed achieved in tests) indicates better performance adaptation
Time frame: Baseline and after 6 weeks
Changes in Body Weight
Participants were weighed before and after the study to calculate body composition analysis. Participants arrived well hydrated, and were instructed to eat at least two hours beforehand. Weighing was performed at the same time slot (± 2 hours). it was measured: \- Body weight (kg)
Time frame: Baseline and after 6 weeks
Changes in Height (cm)
Participants were weighed before and after the study to calculate body composition analysis. Participants arrived well hydrated, and were instructed to eat at least two hours beforehand. Weighing was performed at the same time slot (± 2 hours). it was measured: \- Height (cm)
Time frame: Baseline and after 6 weeks
Changes in BMI (kg/m^2)
Participants were weighed before and after the study to calculate body composition analysis: Participants arrived well hydrated, and were instructed to eat at least two hours beforehand. Weighing was performed at the same time slot (± 2 hours). it was measured: \- BMI (kg/m\^2)
Time frame: Baseline and after 6 weeks
Changes in Fat mass
Participants were weighed before and after the study to calculate body composition analysis: Participants arrived well hydrated, and were instructed to eat at least two hours beforehand. Weighing was performed at the same time slot (± 2 hours). it was measured: \- Fat mass (%)
Time frame: Baseline and after 6 weeks
Changes in Free Fat Mass
Participants were weighed before and after the study to calculate body composition analysis: Participants arrived well hydrated, and were instructed to eat at least two hours beforehand. Weighing was performed at the same time slot (± 2 hours). it was measured: \- Free fat mass (%)
Time frame: Baseline and after 6 weeks