Article Title: Training Volume and Repetition Distance Affect Session Rating of Perceived Exertion and Internal Load in Swimmers

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1 Note. This article will be published in a forthcoming issue of the. The article appears here in its accepted, peer-reviewed form, as it was provided by the submitting author. It has not been copyedited, proofread, or formatted by the publisher. Section: Original Investigation Article Title: Training Volume and Repetition Distance Affect Session Rating of Perceived Exertion and Internal Load in Swimmers Authors: Renato Barroso 1,2, Diego F. Salgueiro 1, Everton C. do Carmo 3, and Fábio Y. Nakamura 2,4 Affiliations: 1 Department of Sport Sciences, Faculty of Physical Education, State University of Campinas, Brazil. 2 Multicentric Research Group in Sports Sciences. 3 School of Physical Education and Sport, University of São Paulo, Brazil. 4 Department of Physical Education, State University of Londrina. Journal: Acceptance Date: January 28, Human Kinetics, Inc. DOI:

2 Training volume and repetition distance affect session rating of perceived exertion and internal load in swimmers Original investigation Renato Barroso 1,2, Diego F. Salgueiro 1, Everton C. do Carmo 3, Fábio Y. Nakamura 2,4 1 Department of Sport Sciences, Faculty of Physical Education State University of Campinas, Brazil 2 Multicentric Research Group in Sports Sciences 3 School of Physical Education and Sport University of São Paulo, Brazil 4 Department of Physical Education - State University of Londrina Running head: Volume and repetition distance affect srpe in swimming Corresponding author Renato Barroso Department of Sport Sciences Faculty of Physical Education State University of Campinas R. Érico Veríssimo, 701 Cidade Universitária Campinas Brazil Fax number: Office number: barroso@fef.unicamp.br Abstract word count: 196 words Text-only word count: 2272 words Number of figures: 2 figures

3 ABSTRACT Purpose: To assess swimmers session rating of perceived exertion (srpe) after standardized sets of interval swimming training performed at the same relative intensity, but with different total volume and repetition distance. Methods: Thirteen moderately-trained swimmers (21.1±1.1yrs, 178±6cm, 74.1±8.3kg, 100m freestyle = 60.2±2.9s) performed four standardized sets (10x100m, 20x100m, 10x200m and 5x400m) at the same relative intensity (i.e., critical speed) and one coach (31yrs, 7yrs coaching experience) rated swimmers efforts. Swimmers srpe was assessed 30min after the training session. Coach s srpe was collected before each training session. Internal load was calculated by multiplying srpe by session duration. Results: When bouts with the same repetition distance and different volumes (10x100m vs 20x100m) are compared, srpe and internal load are higher in 20x100m bouts. Maintaining constant volume, srpe and internal load (20x100m, 10x200m and 5x400m) are higher only in 5x400m bouts. Coach s and swimmers srpe differed in 10x200m and 5x400m. Conclusions: These results indicate that srpe in swimming is affected not only by intensity but also by volume and repetition distance. In addition, swimmers and coach s srpe were different when longer repetition distances were used during training sessions. Therefore, care should be taken when prescribing swimming sessions with longer volume and/or longer repetition distances. Keywords: swimming, critical speed, interval training

4 INTRODUCTION The aim of any sports training is to induce morphological, metabolic and functional changes which cause improvements in athletes performance. An optimum training program should offer the appropriate stimuli (i.e., training loads) to produce performance leading adaptations 1, 2. A theoretical model suggests that internal training load is responsible for training adaptations 3. Additionally, it is considered that internal training load variations throughout periods and cycles of periodization play an important role in the success of the training process 4. Consequently, coaches and practitioners deliberately plan these variations in an attempt to induce adaptations and to improve performance. Therefore, monitoring and controlling internal load are of paramount importance to ensure optimal performance enhancement 5, 6. Internal load is particularly influenced by external load (i.e., training variables), but is difficult to assess 7. In cyclic sports such as swimming, external load is mainly determined by volume (e.g., distance), intensity (e.g., %VO2max) and frequency (number of weekly training sessions) of training, which can be easily controlled. Although external load is the main influencing factor, individual characteristics such as training status and genetic potential may greatly affect internal load 3, 8. According to this paradigm, internal load results from the interaction of external load and individual characteristics. Thus, it is conceivable that the same external load, even when exercise intensity is controlled, does not induce the same physiological stress (internal load) in different athletes, thus affecting training adaptations 9. In spite of the difficulties in controlling and monitoring internal training load, blood lactate, heart rate and oxygen uptake have been suggested for quantifying the magnitude 3, 9. Nevertheless, their assessment is not feasible in a real-world set-up 5, 6, especially in swimming where the environment (i.e., water) may cause equipment malfunction. Training

5 impulses (TRIMP), such as Banister s or Edward s, have been created to quantify training loads. Unfortunately, these TRIMPs also require heart rate data to be calculated, which hinders utilization. In addition, it is arguable whether these assessments would provide valid measures which are comparable to perceptual assessments 10. Perceptual assessments, which include rating of perceived exertion (RPE), have been successfully used both during and after exercise to assess exercise intensity. For instance, according to the estimation-production paradigm, individuals are able to accurately produce any given intensity assessed in a previous exercise trial when they should estimate their perception of effort 11. The results of studies on this paradigm support the use of in-task (during exercise) RPE for prescribing, regulating and assessing exercise intensity In an innovative application of the concept of perceived exertion, Foster et al. 15 used a modified CR-10 Borg scale 16 and asked athletes to rate their effort for the entire workout 30 min after the end of the exercise, yielding the session-rpe (srpe). This srpe positively correlates to the average percentage heart rate reserve 15 and replaces heart rate as a marker of intensity within the Banister s 17 TRIMP concept. Interestingly, even though srpe has been considered a marker of training intensity, there is evidence that it may be sensitive to other external training load determining factors, such as the volume of continuous and stochastic exercise and the repetition duration/distance during interval training 2, Even though the influence of these variables is considered minor, these results were obtained from stochastic and continuous training in dry-land exercises. In addition, it is important to point out that interval training is the most common method used during swimming training 21. Thus, it is essential to understand whether volume and repetition distance during interval training influence swimmers perception of effort and internal training load.

6 Wallace et al. 22 and Barroso et al. 23 reported that swimmers and coaches srpe differed in several training bouts, which implies that external training loads prescribed by the coaches may not induce the desired adaptations in all swimmers. Although the authors did not mention the training sessions performed, it is possible that variables associated with external load affect how swimmers perceive training stimuli, and thus impact on the coaches and swimmers srpe relationship. Thus, the objective of this study was to assess srpe after standardized sets of interval training performed at the same relative intensity in swimmers, but with different total volume and repetition distance. These sets were designed to allow a comparison of training volume and repetition distance. We hypothesized that both volume and repetition distance would affect srpe in moderately-trained swimmers. METHODS Sample Thirteen male moderately-trained swimmers (21.1±1.1yrs, 178±6cm, 74.1±8.3kg, 100m freestyle = 60.2±2.9s) and one coach (31yrs, 7yrs coaching experience) participated in this study. All participants competed regularly in local championships in 50m and 100m in all strokes (n=8) and 100m in all strokes and 200m individual medley (n=3). This study was approved by the University s Ethics Committee, and participants were informed of the objectives, possible risks and benefits of the study and before participation they provided written informed consent. Experimental procedures Participants were familiarized with the CR-10 Borg rating of perceived exertion scale 2 as this was part of their training routine. The rating of perceived exertion (i.e., load intensity) was determined through the srpe method. This method uses a simple question:

7 How was your training session today? The answer was provided 30 min after the end of the session, by choosing a descriptor and a number from 0 to 10, which could also be provided in decimals (e.g., 7.5). Internal load was calculated by the multiplication of srpe by the duration of the training session in minutes. Concerning the coach, the planned load intensity classification was performed before the beginning of each training session. Swimmers were evaluated on six non-consecutive days. During the first and the second days, swimmers were asked to perform either a 200m or 400m repetition aiming at their best results. Times for each distance were plotted and a regression line was drawn for each swimmer. Critical speed (CS) was then calculated as the angular coefficient (i.e., slope) of the regression line between distance-time of these two distances 24. CS was then used during experimental sessions. Experimental training sessions took place in a heated pool (26-28ºC) and were performed as part of the specific conditioning phase, in a randomized order 48h apart. Between-session intervals consisted of light-intensity training sessions. During the experimental session, swimmers performed a standardized warm-up. Ten minutes after the warm-up, swimmers performed one of the standardized sets. Four standardized sets were designed: 10x100m, 20x100m, 10x200m and 5x400m. We chose these sets as they represented a typical training session for these swimmers. In addition, these sets allowed us to investigate the effects of training volume (10x100m vs. 20x100m), and repetition distance (20x100m, 10x200m and 5x400m) on the srpe. All repetitions were performed at the intensity corresponding to individually determined CS. The rest interval between repetitions was individually set to allow a 4:1 effort:rest relationship, which is close to that recommended by Maglischo 25 when using this intensity.

8 Statistical analysis Data are expressed as mean (± SD); normality was assured through standard visual inspection and a normality test (Shapiro-Wilk). In order to compare the effects of volume on the srpe, a paired student t-test was performed comparing 10x100m with 20x100m. Mixed model analysis, assuming set (20x100m, 10x200m or 5x400m) as a fixed factor, and subjects as a random factor was used to compare repetition distance. A Tukey post-hoc adjustment was used in case of significant F-values. In order to compare swimmers and coach s srpe we used the one-sample t-test, assuming the coach s srpe as the hypotheses mean. Significance level was set at p<0.05. RESULTS Average performances in 200m, 400m and CS of swimmers were ± 8.6s, ± 17.7s and 1.11 ± 0.07m s -1, respectively. Figure 1 illustrates srpe means and individual values for 10x100m and 20x100m bouts where it is possible to observe the effects of training volume, keeping all other variables (intensity and repetition distance) constant. The coach rated srpe for 10x100m as 3 and for 20x100m as 4, and these values were not different from those of the swimmers (p=0.57 and p=0.28, for 10x100m and 20x100m, respectively). Figure 2 presents means and individual values of srpe for 20x100m, 10x200m and 5x400m bouts. It can be observed that, keeping volume and intensity constant, the 400m bout induced higher srpe values than 200m (p=0.002) and 100m (p=0.029) bouts. Interestingly, there was no difference between 100m and 200m bouts. Coach s srpe for the 20x100m, 10x200m and 5x400m were 4, 5 and 6, respectively. Coach s and swimmers srpe differed for 10x200m (p=0.005) and 5x400m (p=0.033).

9 Regarding training volume, coefficient of variation (CV) of srpe increased from 16.9% to 19.2%, in the 10x100m and 20x100m, respectively. CV was even higher in the 10x200m (21.6%) and 5x400m (27.2%). DISCUSSION The aim of this study was to compare srpe values and internal load for training bouts with different volumes and repetition distances/durations. The main findings of this study are that both training volume and repetition distance affect srpe and internal load in moderatelytrained swimmers. Even though srpe has been considered a marker of training intensity the possible influence of training volume on srpe can be observed in Foster et al. 2. From their results, it is possible to calculate srpe in 30min and 90min bouts at the same intensity, with srpe for 90min being around 10% higher than 30min (4.8 vs 4.3, respectively). Similar results were obtained by Haddad et al. 20 and Green et al. 19 who reported a minor influence of volume on srpe in taekwondo athletes and physically active subjects, respectively. Although these results were obtained from stochastic and continuous exercises, interval training is the most common method used during swimming training 21. Thus, it is important to know how volume during interval training affects swimmers perception of effort and internal training load. The results of this study demonstrate that interval training volume affects srpe and internal training load. The influence of greater volume on internal load is expected, since internal load is calculated by the multiplication of a marker of intensity (i.e., srpe) by the volume (i.e., duration in minutes). Nevertheless, as srpe is also affected by training volume, the latter has been taken into account twice, overestimating the importance of training volume on internal training load. Therefore, caution should be taken when prescribing longer training volumes.

10 Interestingly, repetition distance also affects srpe. During continuous exercise with constant intensity, in task RPE has been shown to rise linearly 12, 18, 26, 27. The srpe, on the other hand, is supposed to reflect the overall intensity of the training session. It should, then, not be affected by modifying set distance while maintaining constant intensity, as in the present study. However, increasing repetition distance from 100m to 400m induced an increase in srpe without any change in training intensity. Also, internal training load was higher in the 5x400m training session. This result is contrary to those reported by Foster et al. 2 during cycling exercise. These authors did not observe any difference in training load when volunteers performed 30/30s, 60/60s or 120/120s interval training for 30min at the same relative intensity. We did not assess heart rate, oxygen consumption or blood lactate in order to have a physiological variable. These variables are not easy to measure during a swimming session. However, Bentley et al. 28 assessed these variables during two different sets (4x400m and 16x100m) in elite swimmers, which were similar to those used in this study. Even though intensity was a little higher than that in the present study, VO2 and time spent near VO2max, blood lactate and heart rate were not different between sets, suggesting that these variables should be similar in the present study. It is possible that this response is sport-dependent, related to the environment where the exercise is performed. During swimming, drag created by the swimmer s body (i.e., passive drag) and movement (i.e., active drag) is an important factor that hinders displacement. In-task RPE rises during the exercise reflecting a greater effort during longer repetition distances. Thus, fatigue may develop and impair swimmers body positioning 25. A poor body position increases drag, and consequently effort to maintain the same swimming speed throughout the distance 29, ultimately affecting srpe. Alternatively, it is possible to suggest that the findings of this study are dependent on swimmers training status. Garcin et

11 al. 27 observed that moderately-trained athletes rated exercise, at similar relative intensities, as more strenuous than highly-trained athletes. Seiler and Kjerland 30 reported that training near the second ventilatory threshold, similar to the intensity obtained with the CS, is supposed to yield an srpe close to 7. We are surprised by the large variation of srpe responses to the interval training prescribed using the individual CS, especially since Wakayoshi et al. 31 demonstrated a close agreement between CS derived from 200m and 400m trials and the maximal lactate steady-state in swimmers. srpe ranged from < first ventilatory threshold values (i.e., 4) to > second ventilatory threshold (i.e., 7) in our sample, taking as reference the values reported by Seiler and Kjerland 30. Therefore, future studies should clarify the cause of the large variability in srpe in response to the same physiological intensity in swimmers. Alternatively, it is possible that, even though CS is a well-recognized and studied method to prescribe training intensities 32, it overestimated the swimming speed at which anaerobic threshold was achieved in some swimmers. If this is true then swimmers were not swimming in steady state and oxygen uptake was still increasing (i.e., slow component), eventually reaching maximal oxygen uptake if the exercise was of sufficient duration. Thus, it is possible that in the longer distance set (i.e., 5x400m), swimmers attained maximal oxygen uptake 33, thus elevating srpe. The same did not happen in shorter distance sets (i.e., 20x100m and 10x200m), as swimmers oxygen uptake did not reach maximal values (along with ventilation) and srpe was not affected. This result highlights the importance of correctly prescribing intensities 9, especially those near anaerobic threshold (i.e., critical speed). In addition, this fact may have contributed to the increase in the coefficient of variation of srpe and internal load observed with higher volume and longer distances. The higher coefficient of variation means that athletes perceptions of effort are more variable and

12 may represent a challenge for coaches to precisely prescribe internal training loads for all athletes in the same team. Unexpectedly, the srpe expressed by the coach was also affected by volume and repetition distance, indicating that swimming coaches may already take into account the influence of volume and repetition distance observed in this study. However, the coach overestimated srpe (compared to swimmers) in longer repetition distances (i.e., 200m and 400m). The validity and feasibility of prescribing training based on the expected RPE (production mode) in order to reduce the between-subject variation in the training loads and hence induce the desired training adaptations remains to be established. It is important to highlight that only one coach rated the training sessions, and this result may not be reproduced with other coaches. PRACTICAL APPLICATION Increasing volume, by adding repetitions, and/or the distance per repetition seems to be related to amplified inter-individual srpe variability (i.e., coefficient of variation). This fact may hamper internal load control, even if external load is the same and based on individual CS. Thus, alternative methods for prescribing training to a group of athletes aiming at the same internal load might be more appropriate, such as those based on the estimation-production paradigm. This suggestion should be investigated and could alter how interval endurance training is prescribed. CONCLUSION Greater volume and repetition distance during interval training influences srpe, increases inter-individual variability and may affect the coaches and swimmers srpe relationship.

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16 Figure 1 Session rating of perceived effort (srpe, arbitrary units, a.u.) and internal load (a.u.) for 10x100m and 20x100m. Open circles and dashed lines represent individual values. Filled circles and continuous line represent mean (±sd). * - p<0.05 between bouts.

17 Figure 2 Session ratings of perceived effort (srpe, arbitrary units, a.u.) and internal load (a.u.) for 20x100m, 10x200 and 5x400m. Open circles and dashed lines represent individual values. Filled circles and continuous line represent mean (±sd). * - p<0.05 5x400m greater than 20x100m and 10x200m.