Conference PaperPDF Available

Estimating Running Performance Combining Non-invasive Physiological Measurements and Training Patterns in Free-Living

Authors:
  • HRV4Training

Abstract

In this work, we use data acquired longitudinally, in free-living, to provide accurate estimates of running performance. In particular, we used the HRV4Training app and integrated APIs (e.g. Strava and TrainingPeaks) to acquire different sets of parameters, either via user input, morning measurements of resting physiology, or running workouts to estimate running 10 km running time. Our unique dataset comprises data on 2113 individuals, from world class triathletes to individuals just getting started with running, and it spans over 2 years. Analyzed predictors of running performance include anthropometrics, resting heart rate (HR) and heart rate variability (HRV), training physiology (heart rate during exercise), training volume, training patterns (training intensity distribution over multiple workouts, or training polarization) and previous performance. We build multiple linear regression models and highlight the relative impact of different predictors as well as trade-offs between the amount of data required for features extraction and the models accuracy in estimating running performance (10 km time). Cross-validated root mean square error (RMSE) for 10 km running time estimation was 2.6 minutes (4% mean average error, MAE, 0.87 R^2), an improvement of 58% with respect to estimation models using anthropometrics data only as predictors. Finally, we provide insights on the relationship between training and performance, including further evidence of the importance of training volume and a polarized training approach to improve performance.
Estimating Running Performance Combining Non-invasive Physiological
Measurements and Training Patterns in Free-Living
Marco Altini and Oliver Amft1
Abstract In this work, we use data acquired longitudinally,
in free-living, to provide accurate estimates of running per-
formance. In particular, we used the HRV4Training app and
integrated APIs (e.g. Strava and TrainingPeaks) to acquire
different sets of parameters, either via user input, morning
measurements of resting physiology, or running workouts to
estimate running 10 km running time. Our unique dataset
comprises data on 2113 individuals, from world class triathletes
to individuals just getting started with running, and it spans
over 2years. Analyzed predictors of running performance
include anthropometrics, resting heart rate (HR) and heart
rate variability (HRV), training physiology (heart rate during
exercise), training volume, training patterns (training intensity
distribution over multiple workouts, or training polarization)
and previous performance. We build multiple linear regression
models and highlight the relative impact of different predictors
as well as trade-offs between the amount of data required
for features extraction and the models accuracy in estimating
running performance (10 km time). Cross-validated root mean
square error (RMSE) for 10 km running time estimation was
2.6minutes (4% mean average error, MAE, 0.87 R2), an
improvement of 58% with respect to estimation models using
anthropometrics data only as predictors. Finally, we provide
insights on the relationship between training and performance,
including further evidence of the importance of training volume
and a polarized training approach to improve performance.
I. INTRODUCTION AND RELATED WORK
Medium and long distance running is becoming popular,
with millions of people worldwide participating in running
events from 5 km to the marathon distances. While human
performance in running has been analyzed in elite athletes as
well as recreational ones for decades, the scientific commu-
nity is still investigating different aspects behind the limits of
human performance, as recently shown by the Nike break-
ing2 project [1]. Being able to accurately estimate running
performance can be helpful at several levels. First, we could
provide individuals with better race pacing strategies, which
are often guessed based on limited data. Secondly, we could
also tailor training plans to individual abilities, therefore
reducing injury risk.
Different anthropometric, physiological, and training char-
acteristics influence human performance in running. Low
body fat has been associated with better times [2], similarly
to low resting heart rate (HR) and higher heart rate variability
(HRV) [3]. Other physiological parameters measured in the
lab, for example lactate threshold and V O2max, have also
been linked to better running times. In our recent work we
have shown how V O2max estimated from running work-
outs highly correlates with running performance in events
1M. Altini and O. Amft are with Friedrich-Alexander Universitat
Erlangen-Nurnberg (DE) email: altini.marco@gmail.com
between the 10 km and the marathon [4]. Training related
variables, such as training volume (distance per week), as
well as average training speed have been associated to
improved running performance too. Recently, interest has
shifted to training patterns analyzed over weeks or months.
For example, most elite athletes train in a so-called polarized
regime, in which most workouts are carried out at low
intensities, and a few at very high intensity, as opposed
to moderate intensity training, more typical of recreational
runners [5], [6]. Even in recreational runners, a shift to a
polarized training regime resulted in performance improve-
ments [7].
Most literature published on estimating running perfor-
mance however is constrained by small sample size and a
rather homogeneous sample (for example only men, or a
narrow age range or performance range). Variables included
in the model are acquired under laboratory conditions or
supervised settings that are not practical (V O2max, lactate
threshold, biomechanics [2]) Finally, parameters are analyzed
in isolation (for example the impact of polarized training
on performance [5]) and running time estimates accuracy is
suboptimal or has not been cross-validated.
In the past few years, we have witnessed fast technological
developments and integrations between different platforms
and services (e.g. public APIs), resulting in increased avail-
ability of multivariate data streams acquired from mobile
applications and wearable sensors (e.g. GPS, accelerometer,
physiological data). Such developments are providing scien-
tists with data at a scale that is typically not manageable in
regular laboratory studies, and therefore with the opportunity
of providing additional insights on the relation between
physiology, training and performance. While several mobile
applications and wearable sensors have been released on the
market, providing users with metrics reflecting behavior (e.g.
steps taken, distance ran, etc.) limited work has been carried
out to provide insights on the individual’s performance
ability outside of laboratory settings.
In this work we propose the first longitudinal, large scale
analysis of running performance with respect to a wide set
of variables either self-acquired or acquired automatically
and non-invasively in free-living, without laboratory tests
or supervision. Analyzed variables include anthropometrics,
resting physiology, training physiology, training volume,
training patterns and previous performance.
In particular, we used the HRV4Training app [8], [9]
to collect data from 2113 individuals of different fitness
levels, over a time period of 2years, and developed multiple
linear regression models to highlight the relative impact of
different predictors on running performance estimation. We
show that running performance (10 km time) can be esti-
mated accurately from data acquired in free-living, without
supervision or specific laboratory tests. Besides providing
practical estimation models that could be employed by recre-
ational runners to tailor training programs, we also provide
additional insights on the relationship between training and
performance, including confirmative evidence of the impor-
tance of polarized training.
II. DATA ACQUISITION
A. Measurement Protocol
Users downloaded the HRV4Training app from the Ap-
ple Store or Google Play Store and agreed to provide
collected measurements and annotations for research pur-
poses via a consent form embedded in the application.
The HRV4Training app allows a user to measure resting
physiological data (HR and HRV) using the phone camera or
external sensors, and was recently validated with respect to
electrocardiography (ECG) [10]. The application instructed
users to perform the measurement right after waking up while
still lying, to limit the effect of other stressors. In addition,
users could link the HRV4Training app to other services,
such as Strava or TrainingPeaks, so that not only morning
measurements, but also workouts performed during the day,
and associated GPS and heart rate data, would be collected
automatically in the app.
B. Dataset
Data was collected using the HRV4Training app during
2016 and 2017. A total of 2113 users (1891 male, 222
female) met the inclusion criteria: training with a heart rate
monitor, linking the app via third party APIs to collect
workouts data, including at least one 10 km, and taking at
least a month of morning physiological measurements. A
user’s best 10 km time was automatically identified as the
fastest 10 km workout over the 2years, and used as reference
for this analysis. For each identified best 10 km time, the
previous 3months of data were used to extract features re-
lated to a user training volume and patterns. Totally, 464809
morning physiological measurements and 296739 running
workouts were acquired during the 2years longitudinal
study, for an average of 220 morning measurements and 140
workouts with heart rate data per person. Anthropometric
characteristics and reference 10 km times of the users are
listed in Table I.
TABLE I
USE RS ANT HROPO METR IC DATA AND R EF ER EN CE 10 KM TIME
mean sd min max
age (years) 39.80 8.70 18.00 69.08
bmi (kg/m2) 23.24 2.51 16.65 36.59
weight (kg) 73.34 10.53 42.00 122.00
height (cm) 177.41 7.69 149.00 205.00
10km time (minutes) 49.8 7.2 34.2 75.0
Non−Polarized
Polarized
Feb Mar Apr May Jun Jan Apr Jul
120
130
140
150
160
170
140
150
160
170
Date
Running heart rate (bpm)
Moderate intensity
FALSE
TRUE
a) Training polarization features: heart rate data
Non−Polarized
Polarized
FALSE TRUE FALSE TRUE
0
30
60
90
0
10
20
30
Moderate intensity
Count
Moderate intensity
FALSE
TRUE
b) Resulting distribution of workouts at different intensities
Fig. 1. a) Heart rate data for an individual training under a non-polarized
approach (left) and an individual training under a polarized approach (right).
Moderate intensity was defined as HR within 5% of a user’s average.
b) Resulting training intensities distributions highlighting how a more
polarized approach involves less time spent at moderate intensities. Here
we set an arbitrary threshold of 30% of workouts carried out at moderate
intensity, to assign a user to the polarized or non-polarized category, only
for visualization purposes.
III. DATA ANALYSIS
A. Features
We computed features representative of different aspects
that may contribute to running performance. Then, we cre-
ated the following sets to analyze their impact on estimation
accuracy:
Ant: anthropometrics data. A user’s body mass index
(BMI), age and gender.
Rest: resting physiological data (HR and HRV). HR
was computed as the mean HR during the daily morn-
ing measurement, while as HRV feature we used the
square root of the mean squared RR intervals difference
(rMSSD), a marker of parasympathetic activity [3], [9].
Vol: training volume and speed. Average workout dis-
tance and speed.
TrPhy: physiological data during training. We computed
the speed to HR ratio, a feature that relies on the fact
that a more fit (faster) runner would maintain a lower
HR while running at a certain speed, with respect to
less fit (slower) runners. This parameter is the main
predictor behind V O2max estimation models relying on
sub-maximal tests or workouts data [4], [11].
Pol: training polarization. Training polarization refers
to training at different intensities, typically avoiding
moderate intensity training. We derived features from
workouts summaries to analyze the impact of training
polarization on estimated performance. Features were:
percentage of workouts performed at speeds 5% above
or below a user’s average workout speed and the per-
centage of workouts where HR was within 5% of a
user’s average HR rate, a feature used to represent lack
of polarization (see Fig. 1).
Performance: past running performance. Finally, the
last feature set included all previous features plus the
best 10 km time found in the 3months preceding the
fastest time, as previous running performance is highly
predictive of future running performance.
We chose to compute training polarization features as devi-
ations from a user’s average. By avoiding range, maximum
and minimum values we maintain the algorithm’s robustness
to measurement inaccuracies and outliers which often occur
in free-living. All features were computed over the 3months
preceding a user best 10 km time, depending on available
data. An example of features collected is shown in Fig. 2.
B. Running performance estimation
Running performance (10 km running time) was estimated
using multiple linear regression (MLR) models and the
different sets of predictors listed in Sec. III-A. MLR was used
so that coefficients could be easily analyzed and interpreted,
in order to provide further evidence on the importance of
different parameters in the context of running performance.
C. Statistics and performance measures
MLR models were validated using 10-fold cross-
validation. At each iteration, 10% of the data was randomly
selected for validation, while from the remaining 90%, all
users with at least 20 workouts were used as training set.
By selecting only users with a minimum amount of data, we
ensured training patterns could be meaningfully estimated.
However, we validated our models on all users, even the ones
including little data, so that the relation between available
data and accuracy could be investigated. We report Root
Mean Square Error (RMSE) in minutes, Mean Percentage
Error (MPE), in percentage, Pearson’s correlation and ex-
plained variance (R2) for all cross-validated MLR models.
20
25
30
35
1_q 2_q 3_q 4_q
Quantiles of 10 km performance
BMI (kg/m^2)
a) BMI (Ant)
30
50
70
90
1_q 2_q 3_q 4_q
Quantiles of 10 km performance
Arbitrary unit
c) Heart rate to speed ratio (TrPhys)
5
10
15
20
25
1_q 2_q 3_q 4_q
Quantiles of 10 km performance
kilometers per workout
b) Training load (Vol)
0.00
0.25
0.50
0.75
1.00
1_q 2_q 3_q 4_q
Quantiles of 10 km performance
%
d) 'Non−polarized' trainings (Pol)
Fig. 2. Examples of features used to estimate 10 km running performance.
Data were split into quartiles for clarity.
3
4
5
6
7
5 10 15 20 25 30
Trainings included
RMSE (minutes)
a) 10 km time estimate, RMSE
4
6
8
10
5 10 15 20 25 30
Trainings included
MPE (%)
b) 10 km time estimate, MPE
Fig. 3. RMSE and MPE when different amounts of workouts are included
in the analysis. 15 workouts seem sufficient to extract meaningful features
and minimize estimation error.
IV. RESULTS AND DISCUSSION
A. Workouts number
Results of running time estimation for different amounts
of included workouts are shown in Fig. 3. From this analysis,
15 workouts seem sufficient to extract meaningful features
and minimize estimation error.
B. Feature sets
Feature sets introduced in Sec. III-A were used as pre-
dictors in MLR models. Results were best for feature set
Performance, with a RMSE of 2.68 minutes. Estimation was
least accurate when using only anthropometrics data (set
Ant, RMSE = 6.27 minutes) and improved progressively
when adding resting physiological data (HR and HRV, set
Rest, RMSE = 6.07 minutes), training volume and speed
(average kilometers per workout and average speed per
workout set Vol, RMSE = 4.04 minutes), physiological data
during training (speed to heart rate ratio, set TrPhys, RMSE =
3.96 minutes) and training patterns (percentage of workouts
at low and high intensities, set Pol, RMSE = 3.64 minutes).
All results are reported in Table II while Fig. 4 shows Bland-
Altman plots and R2for four MLR models.
TABLE II
RMSE, MPE AND PER AS ON S CO RR EL ATIO N FO R TH E D IFF ER EN T
MO DE LS D EV EL OP ED I N TH IS S TU DY.
Feature set RMSE (minutes) MPE (%) r
Ant 6.27 9.91 0.53
Rest 6.07 9.56 0.57
Vol 4.04 6.25 0.84
TrPhys 3.96 6.08 0.85
Pol 3.64 5.52 0.87
Performance 2.68 4.10 0.93
R2=0.33
0.6
0.8
1.0
1.2
0.6 0.8 1.0 1.2
Predicted − Rest
Reference
10 km time estimation, Rest feature set
R2=0.71
0.6
0.8
1.0
1.2
0.6 0.8 1.0 1.2
Predicted − Vol
Reference
10 km time estimation, Vol feature set
R2=0.76
0.6
0.8
1.0
1.2
0.6 0.8 1.0 1.2
Predicted − Pol
Reference
10 km time estimation, Pol feature set
R2=0.87
0.6
0.8
1.0
1.2
0.6 0.8 1.0 1.2
Predicted − Performance
Reference
10 km time estimation, Performance feature set
−0.4
0.0
0.4
0.7 0.8 0.9 1.0 1.1
Mean, (Reference + Fitted)/2
Residuals
Bland−Altman − Rest feature set
−0.4
0.0
0.4
0.6 0.8 1.0
Mean, (Reference + Fitted)/2
Residuals
Bland−Altman − Vol feature set
−0.4
0.0
0.4
0.6 0.8 1.0 1.2
Mean, (Reference + Fitted)/2
Residuals
Bland−Altman − Pol feature set
● ●
−0.4
0.0
0.4
0.7 0.9 1.1
Mean, (Reference + Fitted)/2
Residuals
Bland−Altman − Performance feature set
Fig. 4. Bland-Altman plots for four models: Ant,Vol,Pol and Performance.
C. Coefficients
MLR models coefficients could not be reported for all
models due to space restrictions. We report here the sign
of the model’s coefficients as they provide insights on the
relation between predictors and estimated performance. In
particular, it is of interest to determine the impact of features
representative of training patterns as derived from workouts.
In our analysis, age, BMI, resting HR, speed to HR ratio and
time spent at moderate HR intensity entered the model with a
positive sign, meaning that a lower value for these predictors
is associated with a faster 10 km. On the other hand,
HRV (rMSSD), average distance and speed, percentage of
workouts performed 5% faster or 5% slower than the average
training entered the model with a negative coefficient. Thus,
according to our dataset and analysis, a more polarized train-
ing regime, with a higher percentage of workouts preformed
either faster or slower than the average workout, as well as
a lower percentage of workouts performed at moderate HR
intensity, is associated with improved performance.
V. CONCLUSIONS
In this work, we used data acquired longitudinally, in free-
living, to provide accurate estimates of running performance
on a dataset of 2113 runners of all levels. We investigated the
relation between anthropometrics data, resting physiology,
training patterns and performance, showing that running
performance can be estimated accurately. The estimation
models developed in this work do not require laboratory
tests, and could be practically employed by the growing
community of recreational runners to estimate performance
and tailor training plans. Results for different feature sets
are consistent with previous results from smaller studies
[3], [7], [5], [4], showing a positive correlation between
higher estimates of V O2max, higher HRV, lower HR, higher
training volume, higher training speed, a more polarized
training regime and running performance.
Our analysis focused on readily available parameters that
can be easily acquired and processed in free-living. However,
more variables could be integrated as metrics linked to
biomechanics and running power are also becoming available
in the consumers market. Additionally, results could be
backed up by an additional laboratory validation. Future
work will aim at both including more parameters as well
as looking at performance changes over time to determine
the estimation model’s ability to track such changes.
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... Strava 31190 [145,146,147,148] Polar 14000 [149] HRV4Training 2113 [150] adidas Runtastic 14773 [P3] To foster more such collaborations, Hicks et al. [30] published elements of their data-sharing agreement, which helps them approaching companies. These elements define data ownership, the scope of data usage, data access, user anonymity, potential publications, and the licensing of results. ...
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... 8 Non-wearable digital hardware includes equipment, such as cycling smart trainers, 9 bike power meters, 10 software platforms that support virtual training, 11 and the monitoring and analysis of training and competition data. 12 Some aspects of performance cannot easily be measured, for example, flow and how in-tune the athlete is with what is going on inside their body. 13 Athlete's feelings of effort and 'flow' are difficult to define 14 but flow has been suggested to be a desirable psychological state linked with peak performance. ...
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Current literature has examined the technical aspects of triathlon, technologies used in triathlon, and coaching practice in isolation. However, what is not known, and what this research will examine for the first time, are the relationship between these elements and how they interconnect and influence each other. The study also examines how coaches decide what technology to use and why, in relation to their coaching philosophy. Seven individual 1-hour interviews were conducted via video conference with national and international triathlon coaches. The coaches (n = 7) had varying backgrounds, including former elite-level athletes, sport science professionals, and health science graduates. Using a qualitative inductive and deductive thematic analysis, four central themes were discovered. Findings indicate that the opportunities and challenges of implementing new and emerging technologies are ongoing, with coaches not always having consistent views, levels of flexibility, or open-mindedness as to which technologies to use and why. Notably, coaches are concerned about athletes' over-reliance on technology and the data it produces, impacting the athlete's perception of their effort. We conclude that despite switching between different philosophical views of technology, coaches ultimately choose a suite of technologies based on comfort in addition to selecting tools that will enhance the performance of their athletes. Coaches also prioritise the health and well-being of their athletes and will use technology to assist in collecting data to aid in this process. Finally, coaches want athletes to stay ‘in tune’ with their inner sense of effort, and not become overly reliant on objective data.
... Additionally, using such data, scientists can not only extend our knowledge from a research perspective, but also develop additional products and features to improve the usefulness of wearables and phones for various applications. 7 To get there, there are a few important requirements. First, the technology deployed must be accurate. ...
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The commercial explosion of wearable sensing devices in the early 2010s forever changed the landscape of wearable computing. In a few short years, wrist-mounted devices such as wristbands and smart watches dominated the market.1 In 2017, this department featured an article titled “What will we wear after smartphones?” highlighting potential pathways for wearable computing as the early enthusiasm for commercial wearable sensors began to wane, and new form factors like on-skin devices gained traction in the research community.2 In the past few years, we have witnessed substantial changes in many of the domains discussed in that article. Sensor validation and comparison with other state of the art or reference systems has become of paramount importance in a saturated wearables market. Similarly, FDA approval or CE marking of smartphone or sensor-based medical applications is now a priority of many of the players targeting healthcare applications. For traditional form factors such as wristbands and other accessories, large improvements have also been made in hardware, thanks to further miniaturization and improved design (see Figure 1). Figure 1. Phone cameras, watches, and rings have become widespread sensing modalities for accurate monitoring of biometric data. Figure 2. Graphs show mean deviation from baseline (lines) with 95% CIs (shaded areas) for daily resting heart rate (RHR), sleep quantity, and step count during −7 to 133 days after symptom onset for COVID-19–positive versus COVID-19–negative participants (panels (a), (c), and (e)) and for COVID-19–positive participants grouped by mean change in RHR during days 28 to 56 after symptom onset (panels (b), (d), and (f)). Acquired with permission from Radin et al.8
... We ran the HRV4training TM to detect variations in HRV. The application is designed based on photoplethysmography (PPG) and has been validated and applied in studies to investigate physiological response [28][29][30]. The output data include the stand deviation of normal-tonormal intervals (SDNN) and the root mean square of successive R-R intervals (RMSSD) calculated based on a 60 s time frame. ...
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Reducing the burden of pain via greenspace exposure is a rising research topic. However, insufficient evidence has been found in relation to the environmental effect itself. Residential greenspace, as a convenient but limited natural environment for urban dwellers, has benefits and services yet to be discovered. Therefore, the current study recruited 24 young adults to evaluate the effects of physical visit to, or image viewing of, residential greenspace on pain perception and related psychophysiological outcomes, via simulated pain. Pain threshold and tolerance were recorded via the level of pain stimuli, and pain intensity was evaluated using the Visual Analog Scale (VAS). The state scale of the State–Trait Anxiety Inventory (STAI-S) and two adjective pairs were employed to measure the state anxiety and subjective stress, respectively. Meanwhile, heart rate (HR), heart rate variability (HRV), and blood pressure (BP) were measured to investigate physiological responses. Besides, Scenic Beauty Estimation (SBE) was also employed to assess participants’ preference regarding the experimental environments. The results revealed that visiting the greenspace significantly increased the pain threshold and tolerance, while no significant effect was observed for image viewing. On the other hand, no significant difference was observed in pain-related psychophysiological indices between the experimental settings, but significantly negative associations were found between the scores of SBE and subjective stress and state anxiety. In conclusion, the current study brings experimental evidence of improving pain experience via residential greenspace exposure, while the related psychophysiological benefits require further investigation.
... Due to this reasons, Hicks et al. (2019) postulated that a plausibility check of the data from portable sensors is an integral part prior to its analysis. Different publications have already shown the potential of portable sensor data from fitness apps to further improve performance prediction (Altini and Amft, 2018;Berndsen et al., 2020;Emig and Peltonen, 2020), to accurately determine the critical speed of runners and to set up pacing strategies (Smyth and Muniz-Pumares, 2020) and also to individualize training plans for marathon preparation (Feely et al., 2020). ...
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Objective: Finishing a marathon requires to prepare for a 42.2 km run. Current literature describes which training characteristics are related to marathon performance. However, which training is most effective in terms of a performance improvement remains unclear. Methods: We conducted a retrospective analysis of training responses during a 16 weeks training period prior to an absolved marathon. The analysis was performed on unsupervised fitness app data (Runtastic) from 6,771 marathon finishers. Differences in training volume and intensity between three response and three marathon performance groups were analyzed. Training response was quantified by the improvement of the velocity of 10 km runs Δv10 between the first and last 4 weeks of the training period. Response and marathon performance groups were classified by the 33.3rd and 66.6th percentile of Δv10 and the marathon performance time, respectively. Results: Subjects allocated in the faster marathon performance group showed systematically higher training volume and higher shares of training at low intensities. Only subjects in the moderate and high response group increased their training velocity continuously along the 16 weeks of training. Conclusion: We demonstrate that a combination of maximized training volumes at low intensities, a continuous increase in average running speed up to the aimed marathon velocity and high intensity runs ≤ 5 % of the overall training volume was accompanied by an improved 10 km performance which likely benefited the marathon performance as well. The study at hand proves that unsupervised workouts recorded with fitness apps can be a valuable data source for future studies in sport science.
... The number of recreational runners taking part in long-distance races such as the marathon has been steadily growing. For the increasing mass of marathon runners, the possibility of accurate estimation of running performance can be helpful to plan optimal race pacing strategies and fulfil the goal-times reducing injury risk (Altini and Amft, 2018). Performance during the marathon is determined by a variety of factors, including the physiological and anthropometric characteristics, and training of the subject (Doherty et al., 2020). ...
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The aim of this work is to provide further validation of a predictive formula for marathon time performance (MPT) published in 2011. The predictive formula has been correlated with new sample points derived mainly from publicly available data on Strava. The new marathon data points confirm the predictive correlation between mean weekly distance run, mean training pace and marathon performance. The RMSE of 5.4 min for MPT in the 2:47−3:36 (hour:min) range is statistically significant. The extension of the correlation validity for MPT below 2:47 (hour:min) is possible but results are affected by a larger RMSE (9.5 min for MPT). Therefore, the predictive formula for the MPT can be used by coaches and athletes to adjust training programmes and to adopt optimal pace strategies during the marathon race.
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Introduction: Exercise interventions for breast cancer survivors have proved their potential to improve clinical, physical, and psychosocial outcomes. However, limited studies have explored exercise effects on autonomic dysfunction and the measurement of exercise tolerance and progression through daily heart rate variability (HRV). Purpose: To analyze the effects of a 16-wk exercise intervention on the autonomic modulation of breast cancer survivors, as well as to examine the evolution of daily measured HRV and its interaction with exercise sessions in this population. Methods: A total of 29 patients who had undergone chemotherapy and radiotherapy were randomly assigned to the exercise group or to the control group. The exercise intervention was delivered remotely through online meetings and consisted of supervised training resistance and cardiovascular exercise 3 times per week. During the intervention all patients measured their HRV daily obtaining the napierian logarithm of the root mean square of successive differences between normal heartbeats (lnrMSSD) and the napierian logarithm of the standard deviation of the interbeat interval of normal sinus beats (lnSDNN) values at four moments: day 0 (the morning of the training sessions), 24, 48, and 72 h after exercise. Results: The results revealed a significant interaction between group and months during the intervention period for lnrMSSD and lnSDNN (p < 0.001). Additionally, there were significant differences in lnSDNN recovery time between months (p < 0.05), while differences in lnrMSSD become apparent only 24 h after exercise (p = 0.019). The control group experienced a significant decrease in both variables monthly (p < 0.05) while exercise group experienced a significant increment (p < 0.05). Conclusion: HRV is daily affected by exercise training sessions in cancer patients. Although results strongly support the role of exercise as a post-chemotherapy and radiotherapy rehabilitation strategy for breast cancer survivors to improve autonomic imbalance, further research is necessary to validate these initial findings.
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Purpose: To establish the validity of smartphone photoplethysmography (PPG) and heart rate sensor in the measurement of heart rate variability (HRV). Methods: 29 healthy subjects were measured at rest during 5 min of guided breathing (GB) and normal breathing (NB) using Smartphone PPG, heart rate chest strap and electrocardiography (ECG). The root mean sum of the squared differences between R-R intervals (rMSSD) was determined from each device. Results: Compared to ECG, the technical error of estimate (TEE) was acceptable for all conditions (average TEE CV% (90% CI) = 6.35 (5.13; 8.5)). When assessed as a standardised difference, all differences were deemed "Trivial" (average std. diff (90% CI) = 0.10 (0.08; 0.13). Both PPG and HR sensor derived measures had almost perfect correlations with ECG (R = 1.00 (0.99; 1:00). Conclusion: Both PPG and heart rate sensor provide an acceptable agreement for the measurement of rMSSD when compared with ECG. Smartphone PPG technology may be a preferred method of HRV data collection for athletes due to its practicality and ease of use in the field.
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In this work, we propose to use anthropometrics and physiological data to estimate cardiorespiratory fitness (CRF) in free-living and analyze the relation between estimated CRF and running performance. In particular, we use the ratio between running speed and heart rate (HR) as predictor for CRF estimation in free-living. The ratio is representative of fitness as lower HR at a given speed is expected for more fit individuals. Then, we analyze the relation between estimated CRF and running performance for 10 km, half marathon and full marathon runs. CRF estimation models were developed using lab-based V O2max measurements. CRF estimates were obtained from data collected in unsupervised free-living in a sample of 532 runners for a period ranging between 1 and 8 months using the HRV4Training app. During the same period, running performance was determined for all runners. We show that the speed to HR ratio provides higher accuracy in CRF estimation compared to resting HR or no-physiological data (15% to 18% reduction in RMSE for person-independent models). Secondly, we found moderate to strong correlations between CRF estimated from free-living data and running performance (Pearson's r = 0.56 − 0.61). We conclude that estimating CRF in free-living using mobile technology and data integration can be a valuable tool to support individualized training plans and to track fitness and performance outside laboratory settings.
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We describe an approach to support athletes at various fitness levels in their training load analysis using heart rate (HR) and heart rate variability (HRV). A smartphone-based application (HRV4Training) was developed that captures heart activity over one to five minutes using photoplethysmog-raphy (PPG) and derives HR and HRV features. HRV4Training integrated a guide for an early morning spot measurement protocol and a questionnaire to capture self-reported training activity. The smartphone application was made publicly available for interested users to quantify training effect. Here we analyze data acquired over a period of 3 weeks to 5 months, including 797 users, breaking down results by gender and age group. Our results suggest a strong relation between HR, HRV and self-reported training load independent of gender and age group. HRV changes due to training were larger than those of HR. We conclude that smartphone-based training monitoring is feasible and a can be used as a practical tool to support large populations outside controlled laboratory environments.
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Objective: In this paper we propose artificial intelligence methods to estimate cardiorespiratory fitness (CRF) in free-living using wearable sensor data. Methods: Our methods rely on a computational framework able to contextualize heart rate (HR) in free-living, and use context-specific HR as predictor of CRF without need for laboratory tests. In particular, we propose three estimation steps. Initially, we recognize activity primitives using accelerometer and location data. Using topic models, we group activity primitives and derive activities composites. We subsequently rank activity composites, and analyze the relation between ranked activity composites and CRF across individuals. Finally, HR data in specific activity primitives and composites is used as predictor in a hierarchical Bayesian regression model to estimate CRF level from the participant's habitual behavior in free-living. Results: We show that by combining activity primitives and activity composites the proposed framework can adapt to the user and context, and outperforms other CRF estimation models, reducing estimation error between 10.3% and 22.6% on a study population of 46 participants. Conclusions: Our investigation showed that HR can be contextualized in free-living using activity primitives and activity composites and robust CRF estimation in free-living is feasible.
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Purpose: To quantify the impact of training-intensity distribution on 10K performance in recreational athletes. Methods: 30 endurance runners were randomly assigned to a training program emphasizing low-intensity, sub-ventilatory-threshold (VT), polarized endurance-training distribution (PET) or a moderately high-intensity (between-thresholds) endurance-training program (BThET). Before the study, the subjects performed a maximal exercise test to determine VT and respiratory-compensation threshold (RCT), which allowed training to be controlled based on heart rate during each training session over the 10-wk intervention period. Subjects performed a 10-km race on the same course before and after the intervention period. Training was quantified based on the cumulative time spent in 3 intensity zones: zone 1 (low intensity, <VT), zone 2 (moderate intensity, between VT and RCT), and zone 3 (high intensity, >RCT). The contribution of total training time in each zone was controlled to have more low-intensity training in PET (±77/3/20), whereas for BThET the distribution was higher in zone 2 and lower in zone 1 (±46/35/19). Results: Both groups significantly improved their 10K time (39min18s ± 4min54s vs 37min19s ± 4min42s, P < .0001 for PET; 39min24s ± 3min54s vs 38min0s ± 4min24s, P < .001 for BThET). Improvements were 5.0% vs 3.6%, ~41 s difference at post-training-intervention. This difference was not significant. However, a subset analysis comparing the 12 runners who actually performed the most PET (n = 6) and BThET (n = 16) distributions showed greater improvement in PET by 1.29 standardized Cohen effect-size units (90% CI 0.31-2.27, P = .038). Conclusions: Polarized training can stimulate greater training effects than between-thresholds training in recreational runners.
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The aims of the present study were to (1) assess relationships between running performance and parasympathetic function both at rest and following exercise, and (2) examine changes in heart rate (HR)-derived indices throughout an 8-week period training program in runners. In 14 moderately trained runners (36 +/- 7 years), resting vagal-related HR variability (HRV) indices were measured daily, while exercise HR and post-exercise HR recovery (HRR) and HRV indices were measured fortnightly. Maximal aerobic speed (MAS) and 10 km running performance were assessed before and after the training intervention. Correlations (r > 0.60, P < 0.01) were observed between changes in vagal-related indices and changes in MAS and 10 km running time. Exercise HR decreased progressively during the training period (P < 0.01). In the 11 subjects who lowered their 10 km running time >0.5% (responders), resting vagal-related indices showed a progressively increasing trend (time effect P = 0.03) and qualitative indications of possibly and likely higher values during week 7 [+7% (90% CI -3.7;17.0)] and week 9 [+10% (90% CI -1.5;23)] compared with pre-training values, respectively. Post-exercise HRV showed similar changes, despite less pronounced between-group differences. HRR showed a relatively early possible decrease at week 3 [-20% (90% CI -42;10)], with only slight reductions near the end of the program. The results illustrate the potential of resting, exercise and post-exercise HR measurements for both assessing and predicting the impact of aerobic training on endurance running performance.
Conference Paper
We describe an approach to support athletes at various fitness levels in their training load analysis using heart rate (HR) and heart rate variability (HRV). A smartphone-based application (HRV4Training) was developed that captures heart activity over one to five minutes using photoplethysmography (PPG) and derives HR and HRV features. HRV4Training integrated a guide for an early morning spot measurement protocol and a questionnaire to capture self-reported training activity. The smartphone application was made publicly available for interested users to quantify training effect. Here we analyze data acquired over a period of 3 weeks to 5 months, including 797 users, breaking down results by gender and age group. Our results suggest a strong relation between HR, HRV and self-reported training load independent of gender and age group. HRV changes due to training were larger than those of HR. We conclude that smartphone-based training monitoring is feasible and a can be used as a practical tool to support large populations outside controlled laboratory environments.
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Performance in intense exercise events, such as Olympic rowing, swimming, kayak, track running and track cycling events, involves energy contribution from aerobic and anaerobic sources. As aerobic energy supply dominates the total energy requirements after ∼75s of near maximal effort, and has the greatest potential for improvement with training, the majority of training for these events is generally aimed at increasing aerobic metabolic capacity. A short-term period (six to eight sessions over 2-4 weeks) of high-intensity interval training (consisting of repeated exercise bouts performed close to or well above the maximal oxygen uptake intensity, interspersed with low-intensity exercise or complete rest) can elicit increases in intense exercise performance of 2-4% in well-trained athletes. The influence of high-volume training is less discussed, but its importance should not be downplayed, as high-volume training also induces important metabolic adaptations. While the metabolic adaptations that occur with high-volume training and high-intensity training show considerable overlap, the molecular events that signal for these adaptations may be different. A polarized approach to training, whereby ∼75% of total training volume is performed at low intensities, and 10-15% is performed at very high intensities, has been suggested as an optimal training intensity distribution for elite athletes who perform intense exercise events.
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Sixty male distance athletes were divided into three equal groups according to their personal best time for the 10km run. The runners were measured anthropometrically and each runner completed a detailed questionnaire on his athletic status, training programme and performance. The runners in this study had similar anthropometric and training profiles to other distance runners of a similar standard. The most able runners were shorter and lighter than those in the other two groups and significantly smaller skinfold values (P less than 0.05). There were no significant differences between the groups for either bone widths or circumferences but the elite and good runners had significantly higher ponderal indices (P less than 0.05) than the average runners, indicating that they are more linear. Elite and good runners were also less endomorphic but more ectomorphic than the average runners. The elite runners trained more often, ran more miles per week and had been running longer (P less than 0.05) than good or average runners. A multiple regression and discriminant function analysis indicated that linearity, total skinfold, the type and frequency of training and the number of years running were the best predictors of running performance and success at the 10km distance.
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To quantify the relationship between total training load and running performance during the most important competitions of the season (national cross-country championships, 4.175- and 10.130-km races). Eight well-trained, subelite endurance runners (age (mean+/-SD): 23+/-2 yr; VO2max: 70.0+/-7.3 mL.kg.min) performed a maximal cardiorespiratory exercise test before the training period to determine ventilatory threshold (VT) and respiratory compensation threshold (RCT). Heart rate was continuously recorded using telemetry during each training session over a 6-month macrocycle, designed to achieve peak performance during the aforementioned cross-country races, lasting from late August to the time that these races were held, that is, mid-February. This allowed us to quantify the total cumulative time spent in three intensity zones calculated as zone 1 (low intensity, lower than the VT); zone 2 (moderate intensity, between VT and RCT); and zone 3 (high intensity, above the RCT). Total training time in zone 1 (4581+/-979 min) was significantly higher (P<0.001) than that accumulated in zones 2 (1354+/-583 min) and 3 (487+/-154 min). Total time in zone 2 was significantly higher than time in zone 3 (P<0.05). A correlation coefficient of r=-0.79 (P=0.06) and r=-0.97 (P=0.008) was found between the total training time spent in zone 1 and performance time during the short and long cross-country races, respectively. Our findings suggest that total training time spent at low intensities might be associated with improved performance during highly intense endurance events, especially if the event duration is approximately 35 min. Interventional studies (i.e., improving or reducing training time in zone 1) are needed to corroborate our findings and to elucidate the physiological mechanisms behind them.