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Validity of Daily and Weekly Self-Reported Training Load Measures in Adolescent Athletes

Phibbs, Padraic J.1,2; Roe, Gregory1,2; Jones, Ben1,2; Read, Dale B.1,2; Weakley, Jonathon1,2; Darrall-Jones, Joshua1,2; Till, Kevin1,2

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Journal of Strength and Conditioning Research: April 2017 - Volume 31 - Issue 4 - p 1121-1126
doi: 10.1519/JSC.0000000000001708
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Abstract

Introduction

The quantification and evaluation of training load (TL) data are important for practitioners working with athletes to maximize positive training outcomes and minimize negative risk factors (e.g., illness, overtraining, and injury) (6,7,9). In professional sporting environments, TL data can be easily obtained because athletes undertake the majority of their training under the supervision of their respective coaching and support staff. However, in late specialization sports (e.g., rugby union), adolescent athletes may undertake training with multiple teams supervised by various coaches concurrently (14), as they are not contracted to one particular organization. Coordinating the optimal training program for youth athletes is essential to maximize player development; however, collecting valid and reliable information on accumulated TLs can be challenging (15).

In adolescent sport, the availability of expensive TL monitoring technologies may also be limited compared with elite adult athletic environments. Session rating of perceived exertion (sRPE; duration × intensity), has been shown to be a valid measure of global TL in collision sports (3) and highly correlated with heart rate and blood lactate measures (4,5). Therefore, the use of sRPE may be useful for practitioners working in adolescent athletic populations to gather data for training design and monitoring purposes (9). Recently, RPE has also been shown to be temporally robust from 5 minutes to 24 hours after exercise using a visual-analogue scale (2). However, as mentioned previously, many coaches working with adolescent athletes may not have contact on a daily basis to collect TL data using this method. Therefore, the validity of a self-reported measure in the absence of practitioners, away from the training environment, would likely have relevance for the youth athlete engaged in various training programs.

Daily TL questionnaires and weekly recall diaries are often used in practice but are suggested to have limitations related to accuracy and compliance (11,16). Currently, there are limited quantitative data on the precise margins of error in these self-reported data collection methods (1). Monitoring training volumes have been previously shown to have a significant margin of error using a self-reported measure of training duration in adult athletes (1). A freely accessible Web-based self-reported questionnaire could provide a simple solution for individual athletes to remotely report their TL when undertaking training sessions away from sports science or strength and conditioning staff. Training exposures could then be modified to optimize an athlete's workload and to reduce the likelihood of potential injuries associated with large variations in workloads on an individual basis (6). A Web-based questionnaire could gather useful and trustworthy information, with minimal burden to the athlete, and could also be time stamped to monitor compliance (15). Therefore, the primary aim of the present study was to assess the levels of agreement between the criterion measure of supervised sRPE collection (sRPE30min) (5) and a freely accessible, self-reported, Web-based, TL questionnaire reported 24 hours after exercise (sRPE24h).

Additionally, as weekly TL diaries are frequently used in research and practice to quantify TL in athletes (9,10), the validity of such methods also need to be assessed because of their previously suggested limitations (11,15). The accuracy of TL recall has been suggested to increase with time (15); however, weekly TL diaries are less time consuming for practitioners to administer and also for athletes to complete. If demonstrated valid, a weekly diary may provide a favorable method to collect this information compared with a daily questionnaire because of the reduced time commitment of both parties. Therefore, the secondary aim of the study was to assess the levels of agreement between a weekly training diary collected via a similar Web-based questionnaire (sRPEweekly) and the summated sRPE24h collected daily over the same training week (∑sRPE24h).

Methods

Experimental Approach to the Problem

The study was designed to evaluate the validity of a daily TL questionnaire by assessing the level of agreement between criterion sRPE (and its individual components; duration and intensity) collected 30 minutes after exercise (sRPE30min), and sRPE collected 24 hours after training remotely (sRPE24h). All participants were familiar with the sRPE30min collection method because it was a regularly used measure of TL quantification at the rugby academy. They were also familiarized with the Web-based questionnaire design (Google Forms; Google, Mountain View, CA, USA) before the study, completing the sRPE24h daily over the previous 3 months. To assess the validity of a weekly TL diary, on a subsequent week, sRPEweekly was completed on the final day of the training week (recalling the intensity and duration for all field-based training sessions completed over the previous 7 days on the same Web-based platform) and assessed for agreement with the summated sRPE24h that was also completed daily over the same period (∑sRPE24h).

Subjects

Thirty-six male adolescent rugby union players (mean ± SD; age, 16.7 ± 0.5 years; height, 182.6 ± 6.3 cm; weight, 84.3 ± 10.7 kg) were recruited for the study from a regional academy squad (highest regional playing standard for this age group). Ethics approval was granted by the Leeds Beckett University ethics committee, and all participants and parents were provided with a plain language statement outlining the procedures and potential risks of participation. Following an opportunity to ask any questions regarding the study to the lead researcher, all participants and parents provided written informed consent before participation.

Procedures

Criterion Training Load Measure

Following a typical field-based training session, all participants provided an RPE measure 30 minutes after exercise to the lead researcher, which was multiplied by the timed session duration for each individual (determined by the lead researcher) to provide the criterion sRPE value in arbitrary units (AU). The RPE selection was made nonverbally, by pointing to the desired text descriptor on a modified Borg category ratio-10 (CR-10) scale (5), blinded from the other participants to avoid external influence on selection.

Self-Reported Daily Training Load Questionnaire

Participants completed an online questionnaire via a freely accessible Web-based platform approximately 24 hours after sRPE30min collection (24.2 ± 0.4 hours), following an e-mail notification containing the link to the questionnaire. The duration values reported were the participant's recollection of the session durations to the nearest minute, and the corresponding intensity value was selected via a drop-down menu of text descriptors corresponding to the modified Borg CR-10 scale (5).

Self-Reported Weekly Training Load Diary

On a subsequent training week, the participants were asked to complete the sRPEweekly on the final day of a training week, reporting training durations and intensities for all field-based training activities undertaken that week using the same Web-based platform as the sRPE24h. Ideally, the sRPEweekly would also be compared with the criterion measure of sRPE30min for each individual session. However, as a result of the various training locations for each athlete, this was not possible because the participants may train with school, club, academy, or representative teams within any particular training week. Therefore, the level of agreement of the sRPEweekly was assessed against the ∑sRPE24h measure, which was also recorded each day of that training week.

Statistical Analyses

Agreement between the criterion measure of sRPE30min and practical measure of sRPE24h, as well as the agreement between ∑sRPE24h and sRPEweekly, for sRPE, duration, and intensity were assessed using an Excel spreadsheet designed to calculate the mean bias , typical error of the estimate (TEE; ), and Pearson correlation coefficient, all with 90% confidence limits (12). All data were log transformed for analyses to reduce bias as a result of nonuniformity error , excluding the regression analysis (12). Raw data were presented to report the regression equations, mean, and SD of the criterion and practical measures. Standardized measures were calculated using back-transformed data based on the Cohen's d effect size principle using the following equation: (12). The standardized mean bias was rated as trivial (<0.2), small (0.2–0.59), medium (0.6–1.19), or large (1.2–1.99) (13). The standardized TEE was rated as trivial (<0.1), small (0.1–0.29), moderate (0.3–0.59), or large (>0.59) (12). The magnitude of correlation was rated as trivial (<0.1), small (0.1–0.29), moderate (0.3–0.49), large (0.5–0.69), very large (0.7–0.89), or nearly perfect (0.9–0.99) (13).

Results

The agreement between the criterion sRPE30min and practical measure of sRPE24h for sRPE, duration, and intensity are presented in Table 1. The agreement between ∑sRPE24h and sRPEweekly measures for sRPE, duration, and intensity are presented in Table 2. The regression plots for the agreement between the criterion sRPE30min and practical measure of sRPE24h for sRPE, duration, and intensity are presented in Figure 1, and the regression plots for the agreement between ∑sRPE24h and sRPEweekly measures are presented in Figure 2. The regression equations, slope, and intercept values are presented in Table 3.

Table 1.
Table 1.:
Agreement between criterion (sRPE30min) and practical measure (sRPE24h) for sRPE, duration, and intensity.*†
Table 2.
Table 2.:
Agreement between practical measures of ∑sRPE24h and sRPEweekly for sRPE, duration, and intensity.*†
Figure 1.
Figure 1.:
Regression plots for agreement between criterion (sRPE30min) and practical measure (sRPE24h) for sRPE (A), time (B), and intensity (C). AU = arbitrary units.
Figure 2.
Figure 2.:
Regression plots for agreement between practical measures of ∑sRPE24h and sRPEweekly for sRPE (A), time (B), and intensity (C). AU = arbitrary units.
Table 3.
Table 3.:
Intercept and slope values with 90% confidence limits (CL) and regression equations for all comparisons.*

Standardized biases were trivial between sRPE30min and sRPE24h for sRPE, duration, and intensity. Standardized TEE was small between sRPE30min and sRPE24h for sRPE and intensity, and moderate for duration. Standardized biases were trivial between ∑sRPE24h and sRPEweekly for sRPE, duration, and intensity. Standardized TEE was moderate between ∑sRPE24h and sRPEweekly for sRPE, duration, and intensity.

Discussion

The main finding of this study is that the self-reported daily TL questionnaire 24 hours after exercise showed high levels of agreement with the criterion measure of supervised sRPE collection 30 minutes after exercise. The sRPE24h had trivial mean bias, small TEE, and nearly perfect correlation, and therefore, it can be considered a valid and robust method of TL quantification for practitioners and sport scientists who are providing remote support for adolescent athletes. This method provides a freely accessible, Web-based alternative for TL quantification, which may be used with large numbers of athletes, to provide accurate data for training monitoring purposes.

Another important finding of the present study is that although sRPEweekly showed trivial bias and very large correlations compared with ∑sRPE24h, the moderate TEE questions its potential use as a practical TL quantification method. As small week-to-week changes in TL (e.g., ∼10%) have been related to injury risk (6), the use of a weekly training diary with a typical error of 28.5% would make it impossible to detect small meaningful changes in TL that could be placing athletes at a greater risk of injury. A recent study investigating the factors that influence self-reported measures suggested that longer recall periods were associated with greater error (15). It has also been suggested that more experienced athletes have a better ability to recall training information (17). Therefore, the validity of weekly self-reported TL methods may need to be assessed in more experienced athletes for population-specific application. In conclusion, the use of a self-reported Web-based daily TL questionnaire can be considered a valid and robust method for quantifying TL in adolescent athletes, unlike the weekly TL diary.

The results of this study are limited to those populations who have been familiarized with this method for a considerable length of time. Young athletes have been suggested to have difficulty in understanding sRPE; however, with adequate familiarization and education, this method may be implemented successfully, especially in older adolescents such as the participants in this study. Adolescents are progressively capable of understanding mathematical processes and should have the cognitive ability to understand and rate their sRPE at the under-18 age category (8). Although the participants were informed that this was not a memory test and that the values provided 24 hours later should reflect the perception of the session at that time, it does not discount the possibility of athletes simply remembering the value reported the day before. However, these results support the findings of a recent study where recall of perceived exertion remained consistent up to 24 hours after exercise in a supervised environment (2). Our findings provide further flexibility for strength and conditioning coaches and sports science support staff by demonstrating the validity of a remote collection method compared with the previous study.

Practical Applications

Considering the accuracy and practicality of the self-reported daily TL questionnaire, where multiple athletes can report workloads remotely without the need for practitioners to be present, the sRPE24h offers a valid and robust method for TL quantification. The weekly TL diary may not be suitable for practical use because of the substantial TEE associated with this method, where the signal may be lost in the noise.

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Keywords:

training load; perception of effort; athlete monitoring; youth

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