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Original Research

Competition Load Described by Objective and Subjective Methods During a Surfing Championship

FernAndez-Gamboa, Iosu1; Yanci, Javier2; Granados, Cristina2; Freemyer, Bret3; Cámara, Jesús2

Author Information
Journal of Strength and Conditioning Research: May 2018 - Volume 32 - Issue 5 - p 1329-1335
doi: 10.1519/JSC.0000000000001973
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Abstract

Introduction

Surfing has developed a multimillion-dollar worldwide business (13), and it will be included in the 2020 Olympic Games. The World Surf League (WSL) holds 185 international competitions per year around the globe with more than 1,000 professional athletes inscribed (3,4,13,15,18–20,26), and surfing competitions are organized in more than 98 countries (3,4,13,15,18–20,26). Previous research on surfing focused on the characteristics of surfing competition (3,4,15,18–20). On the one hand, a previous study to assess the physiological demands during a surfing heat, in the top 30 ranked surfers from the New Zealand surf association, has shown a mean heart rate (HRmean) of 139 ± 11 b·min−1 (64% of their maximum HR [HRmax]) and a peak HR (HRpeak) of 190 ± 12 b·min−1 (87% of their HRmax) (3). On the other hand, the physical demands (external load) have been carried out with global positioning system (GPS) units during both, training sessions and competitive heats (18,23). Specifically, it has been reported that during a 2-hour surfing training session, participants covered a total distance of 6,293.2 ± 1826.1 m (range = 4,491–9,527 m) with a consistent decline in HRpeak and HRmean (20). Nevertheless, during a 20-minute surfing competitive heat, the total distance covered was 1,605 ± 313.5 m (18).

Although objective methods have been used to quantify the physical and physiological demands during surfing (18,23), an HR monitor transmitter belt fastened around the sternum and a wrist GPS unit during surfing have a major drawback: surfers complain about their comfort during paddling with those devices. Besides, considering that during a surfing heat, total paddling time represents approximately the 51–58% of a surfing heat (3,19) and, secondly, that sprint paddling is a key action leading to wave riding (24); the use of these devices could hamper the efficiency of the paddling action. The rating of perceived exertion (RPE), which was designed to be practical (20), is a subjective method that combines the external and internal load into a single score and does not require HR and GPS units. Besides, this score is also affected by ventilation rate, psychological states, and environmental conditions (20), the latter having demonstrated its importance during surfing competitions (3,17,18,20,21,23). The RPE has been shown to be a valid and efficient method of measuring training load (17), even in sports characterized for their multiple high-intensity bouts (12), such as surfing. Therefore, considering the intensity profile of a surfing competition, where high-intensity actions follow, repeatedly, lower intensity actions (18,19), the RPE could be an inexpensive and easy-to-use method to assess the surfers external and internal loads. Furthermore, because of the nature of surfing, where surfers are continuously subjected to apneas of different duration, the assessment of differentiated RPE (dRPE), such as the respiratory RPE (RPEres) and muscle leg RPE (RPEmus), as used in other sports (14,16,25), could provide physical trainers and surfers themselves a deeper understanding of the characteristics of the training or competition load. Plus, this is the first study to tackle the association between dRPE and the objective methods.

Because the judges are responsible for scoring the performance of the surfers during wave riding, based on key elements such as the characteristics of the maneuvers (26), we hypothesized that the longer the wave-riding distance and duration, the greater the chance of performing a combination of major maneuvers and, thus, the better the score. Nevertheless, we are unaware of any study that assessed the relationship between the activity profile of surfers and the judges' score. Likewise, to understand the association between competitive quantification objective and subjective methods with score, as it may be relevant to acknowledge if the heat load (HL) could be an important factor for surfing performance.

The purposes of this study were threefold: (a) to describe the competition load of surfers during a surfing heat through objective (GPS) and subjective methods (dRPE), (b) to analyze the relationship between objective and subjective methods, and (c) to analyze the association of the objective and subjective methods with the judges' score.

Methods

Experimental Approach to the Problem

We use an observational design to examine the relationship between objective and subjective competitive surfing loads. Data were collected during a surfing competition at a national-level open division competition. The study was conducted during the “Euskaltel Euskal Zirkuitua” championship in July 2015, hosted by the Basque Country Surfing Association, as part of the open category 3-stop tour. Participants wore a GPS on the wrist during the heat. On completing the heat, participants were assessed for the RPEres and RPEmus.

Subjects

Ten surfers participated in this study (28.50 ± 11.09 years, 177.10 ± 5.54 cm, 70.20 ± 5.49 kg, 22.37 ± 1.25 kg·m−2) and reported a minimum of 7 years of experience (16.40 ± 9.55 years). They currently were engaged in 2 to 4 surfing training sessions per week (3.20 ± 0.28 d·wk−1). Participants were free of injuries at the time of the study. All participants received a clear explanation of the study, including the risks and benefits of participation. Written informed consent was obtained from each of the participants and parents or guardians (i.e., for underage players). Participants were then familiarized with the use of the 0–10 scale RPE assessment. The study and its procedures were approved by the Institutional Review Board (Ethics Commission for Research and Teaching [CEID] 2015-130) at the University of the Basque Country (UPV/EHU) and met the ethical standards in Sport and Exercise Science Research (10).

Procedures

Objective Load

Objective loads were monitored with a GPS device (Polar Electro V800; Polar Inc., Kempele, Finland) attached to the wrist of the participants and outside the wetsuit. In every trial, the conditions of the GPS were considered acceptable (wrist device connected to at least 8 satellites) and collected at a sample frequency of 2.4 Hz. The GPS was synchronized at least 5 minutes before each heat with a chronometer and a stationary video camera (Canon EOS 5D; Canon Inc., Tokyo, Japan). The camera was set in the judges' area so that it could capture the entire range of wave riding and to identify the surfer's specific actions in each heat. The beginning of the heat was marked in the chronometer with a lap enabling the trimming of the video from the start to the end of the heat. Surfing activities during the heats were coded as time spent in wave riding (s), paddling time (s), and the stationary time (s). The GPS parameters included the total wave-riding time (s) and paddling distance (m). Subsequently, wave-riding time and paddling time parameters were determined through video recordings. The recordings were paused each time a change in the coded activity occurred, and the duration time for the activity was recorded. The active distance and active time were calculated as shown in equations 1 and 2, respectively.

Besides, each wave-riding distance, time, maximum, and mean velocities were also obtained.

Perceived Exertion Subjective Load

Ten minutes after the end of each heat, perceived exertion (PE) was obtained from each participant using the 0–10-point Foster scale (7,9). The surfers responded to 2 sequential questions: (a) How intense was your session on your chest? and (b) How intense was your session on your legs? (1). A 10-minute delay was chosen so that particularly difficult or easy segments near the end of heats would not influence the participant's cumulative heat rating (7). The participants had to differentiate between 2 types of RPE: local (leg, muscular), which assess strain in the working muscles (RPEmus) and central (chest, respiratory), assessing strain on perceived tachycardia, tachypnea, and even dyspnea (RPEres) (1,2,22). An exercise score, referred to as HL, was calculated by multiplying the duration of the heat's active time (paddling time + wave-riding time − stationary time), by the RPEres or RPEmus, as previously described (1,8,9). The corresponding HLs were named RPEres HL or RPEmus HL and measured in arbitrary units.

Surfing Official Scores

The official scores of each participant were obtained from the competition's Internet broadcasting service. All the judges involved in the competition were assigned by the Basque Country Surfing Association and used the score criteria of the WSL. Therefore, judges analyzed the following elements: commitment and degree of difficulty, innovative and progressive maneuvers, combination of major maneuvers, variety of maneuvers, and speed, power, and flow (8). The judging scale was 0.0–1.9 Poor, 2.0–3.9 Fair, 4.0–5.9 Average, 6.0–7.9 Good, and 8.0–10.0 Excellent (26).

Statistical Analyses

The results are presented as mean ± SD. All variables were normal distributed and satisfied the equality of variances according to Kolmogorov-Smirnov test and Levene's tests, respectively. Pearson product-moment correlation coefficient (r) with 90% confidence limits (CLs) was calculated to determine the relationships among the parameters obtained from the objective and subjective methods, as well as judges' scores. The magnitude of correlation between analyzed variables was assessed with the following thresholds: <0.1, trivial; = 0.1–0.3, small; <0.3–0.5, moderate; <0.5–0.7, large; <0.7–0.9, very large; and <0.9–1.0, almost perfect (11). Data analyses were performed using the Statistical Package for Social Sciences (version 23.0 for Windows, SPSS Inc., Chicago, IL, USA). Statistical significance was set at p < 0.05.

Results

The descriptive characteristics of all surfers during individual heats are presented in Table 1. The PE and perceived HL according to the muscular and respiratory systems are also presented in the same table.

T1
Table 1.:
Objective and subjective method heat load (HL) variables measured during one heat of a surfing competition.*

It was observed that a very large and significant correlation was found between wave-riding distance and RPEres HL (r = 0.79; ±0.26 CL, p < 0.01, 99.5/0.4/0.1, very likely) (Figure 1). Also, a very large and positive correlation was found between active time and both RPEres HL (r = 0.75; ±0.29 CL, p < 0.05, 99.0/0.8/0.2, very likely) (Figure 2A) and RPEmus HL (r = 0.83; ±0.22 CL, p < 0.01, 99.8/0.2/0.0, most likely) (Figure 2B). Lastly, RPEmus HL was significantly correlated with stationary time (r = 0.79; ±0.26 CL, p < 0.01, 99.5/0.4/0.1, very likely). No other significant correlations were found between the remaining objective and subjective variables (p > 0.05).

F1
Figure 1.:
Correlation between wave-riding distance (m) and respiratory perceived exertion heat load (RPEres HL), AU = arbitrary units; CL = confidence limit.
F2
Figure 2.:
Correlation between active time (minutes) and respiratory perceived exertion heat load (RPEres HL) (A) and muscular perceived exertion heat load (RPEmus HL) (B), AU = arbitrary units; CL = confidence limit.

Moderate and significant correlations were found between the judges' score and total wave-riding distance (r = 0.37; ±0.50 CL, p < 0.01, 77.7/12.5/9.8, likely), and large correlations were found between the judges' score and wave-riding duration (r = 0.68; ±0.34 CL, p < 0.001, 97.6/1.8/0.6, very likely). No other objective variables (i.e., total distance, paddling distance, stationary, active time, wave-riding peak velocity, wave-riding mean velocity) were significantly correlated with judges' scores. Conversely, very large and significant correlations were found between the RPEres and judges' scores (r = 0.83; ±0.22 CL, p < 0.01, 99.8/0.2/0.0, most likely) (Figure 3). Neither the RPEres HL nor the muscular perceived exertion (i.e., RPEmus and RPEmus HL) significantly correlated with the judges' scores.

F3
Figure 3.:
Correlations between judges' scores and respiratory perceived exertion (RPEres). CL = confidence limit.

Discussion

The purpose of this study was to describe the physical demands of a surfing heat during a competitive event, as determined by both objective and subjective methods. We analyzed the association among these variables and determined how these measures correlated with the judges' scores. To our knowledge, this is the first study to assess dRPE (i.e., respiratory and muscular) workload in a surfing competition, and it is also the first to analyze the association between the objective and subjective methods to quantify the physical demands in surfing. This is important because it provides coaches and athletes a practical and inexpensive tool to quantify the physical activity during a surfing. The main finding of this study was that significant correlations exist between wave-riding distance and respiratory workload and between active time spent surfing and to both respiratory (RPEres HL) and muscular exertions (RPEmus HL). Previously, the relationship between the maneuvers and the judges' scores in competitive surfing has been studied (15); however, this is the first study to examine the association between quantified workloads in a surfing competition with the judges' score. Our results demonstrated the judges' score were correlated with the total wave-riding distance, wave-riding duration, and RPEres.

Surfing performance has been characterized in previous studies by analyzing the paddling distance, wave-riding distance, wave-riding duration, stationary time, and active time (3,20,23). However, one of the novelties of this study is that we analyzed the peak and mean wave-riding velocities. These parameters are relevant to performance and are essential to understanding the intensity output while surfing. The results of our study demonstrated that the average wave-riding peak velocity during a 20-minute heat in a national surfing contest was 0.61 ± 0.25 m·s−1 and the wave-riding mean velocity was 0.50 ± 0.26 m·s−1.

Surfers in our study covered a total distance of 447.51 ± 126.31 m in a heat, which was a noticeably lower distance than the 1,605 ± 313.5 m reported by Farley et al. (2012) during a competitive heat of the same duration. Because the ocean is not a static environment, the different surfing conditions might explain the differences between studies. In addition, surfers in our study were active 40.1% of the time (i.e., paddling and wave riding), 59.9% of the time stationary (sitting or lying on their boards), and 3% riding on waves. The surfers in Farley's study spent 62% of the heat time as active and a 8% of that time riding waves (3). The reason for higher percentage of active time is due to paddling between the sets of waves, waiting or resting for waves, then having to paddle to reposition in the take-off area (3). A previous study analyzing the time motion analysis of professional surfers during a competitive heat revealed that their active time was 58.6%, whereas their stationary time was 41.4% (19). The wave-riding time was similar to the results found in our study (3.8% vs. 3.1% of the total time), although professional surfers spent 18.5% more of their heat time paddling, and consequently, less time as stationary as in our study.

Farley et al. (2012) additionally reported a paddled distance of 947.4 ± 185.6 m and a wave-riding distance of 128.4 ± 25 m for a 20-minute heat. In our study, the distance paddled and the wave-riding distance were 74 and 27% less, respectively. There are also considerable differences regarding the wave-riding duration among studies; while in our study, the total wave-riding duration during a 20-minute heat was 0.24 seconds, Mendez-Villanueva (19) reported 57 seconds, and Farley et al. (2012) 1.6 minutes. Because competitive level may influence the surfers' activity pattern (19), the differences among studies in the time motion analysis might be partially due to the differences in the expertise of the participants. Nevertheless, differences in the surf conditions (3) (i.e., swell size, wave length, and wave frequency among many others) and beach break typology have been reported to influence the activity performed by surfers (3,17,18,20,21,23). The physical demands during surfing are dependent on many factors. These partially include wave and equipment selection (3,18,19), intrinsic motivation of the participants (3,17,19), and the season of the year (i.e., preseason, competition season, and off-season). Although the results of objective methods to measure the surfing performance have been previously reported (3,5,6,18,21,23,24,26), an understanding of the surfers' physical demands, as quantified by subjective methods in this study, may confer a deeper understanding of the mechanisms underpinning surfers' physical demands. To the best of our knowledge, no previous research has reported the dRPE of surfers after a competitive heat. In this study, the RPEres and RPEmus of competitive surfers were 4.35 ± 1.54 and 3.25 ± 0.79, respectively, after a 20-minute heat. The RPEres HL was 36.60 ± 21.90, and RPEmus HL was 28.25 ± 15.23.

Aerobic conditioning seems to be an important component of fitness for surf athletes, as is directly linked to the physical capacity to catch as many waves as possible during a heat and could be the difference between winning and losing (3). It has been observed that during a 20-minute surfing heat, surfers performed at an intensity ranging from 55% to 90% of their HRmax, suggesting that not only the aerobic system is solicited, but also it is intercalated with bouts of high-intensity exercise (3). In our study, the relatively low RPEres and RPEres HL highlight the physiological demands imposed on each surfer. These are beholden to activity durations that are subject to the surf conditions, beach break typology, and surfer's tactical decisions (3,17,18,20,21,23). In addition to the aerobic demands, the intermittent nature of surfing activity requires different types of muscular work (i.e., upper- vs. lower-body, isometric vs. dynamic contractions) (18). Surfers are required to have highly developed upper-body and lower-body strength and power (5,24). Surfing requires upper-body paddling strength to overcome a higher resistance initially and then to accerlate on the surfboard to top speed (24), also maximal power force production for greater propulsion in water and, anaerobic endurance to withstand long durations of constant paddling (3). Lower-body strength and power is related to perform maneuvers and wave riding (5). However, in our study, RPEmus and RPEmus HL values were relatively low. The short duration of the time spent in wave riding and the long paddling time back to the break may have had a low impact on respiratory and muscular exertion. Nevertheless, we need to point out that the subjective parameters, as well as the objective parameters, are highly influenced by the surf conditions and other factors, such as strategic decisions, equipment (3,18,19), level of motivation of the surfers (3,17,19), judging criteria, or season of the year, and therefore, different results would be expected in a same duration competitive heat but with different surfing conditions. We do consider therefore, that surfing conditions should be reported in any surfing study performed, to carefully compare the results. Because this study is the first one to quantify dRPE in surf, further research is needed to obtain more accurate conclusions regarding surfing workloads in a variety of weather conditions.

One of the more used objective methods for quantifying load during training or competition sessions is HR monitoring (1). However, this method in real-time surfing competition is limited because of technical problems, as the HR monitors do not perform well in water conditions or under the athlete wetsuit, the expertise knowledge involved and the time-consuming process of collecting the data from surfers in every session (1), and the uncomfortable feeling of wearing the device while paddling. In this regard, the assessment of the physiological RPEres HL could result in a better understanding of the required competition load needed to optimize the sport session process (1), especially for surfers or coaches who do not have the equipment to measure the HL variables trough objective methods. However, although in other sports, the validity of the subjective methods has been verified to quantify the competition load (14,25), to the date, we did not find any study that has analyzed the association between objective and subjective methods in surf. In this study, a large and significant relationship between wave-riding distance and RPEres HL was found (r = 0.79; ±0.26 CL) (Figure 1). On the other hand, the active time was also very/most likely largely related to both RPEres HL (r = 0.75; ±0.29 CL) (Figure 2A) and RPEmus HL (r = 0.83; ±0.22 CL) (Figure 2B). The subjective method seems to be a good instrument, because of the positive relationships with objective method, to assess the HL of a surf competition.

In competitive surfing, the athletes are judged on their ability to perform radical maneuvers in the most critical section while riding the wave (15). Previous research has provided descriptive data of the maneuvers executed and scores received (15), but to the date, no research has been undertaken to explain the relation between wave-riding performance and the received judges' score. It seems crucial to gain some insights in the relation between the physical demands of a surfing heat and the obtained scores. Our results demonstrated that judges' scores were significantly and moderately correlated with the total wave-riding distance (r = 0.37; ±0.50 CL, p < 0.01), large and significant relationship with wave-riding duration (r = 0.68; ±0.34 CL, p < 0.001), and a very large significant correlation with RPEres (r = 0.83; ±0.22 CL, p < 0.01, 99.8/0.2/0.0, most likely) (Figure 3). Judges analyze different elements when scoring waves; some of these elements are directly related to the wave characteristic, as speed, power, flow, and commitment of the surfer (26). A longer wave will provide a surfer more time and distance to perform more variety of innovative and progressive maneuvers, allowing a combination of major maneuvers, with a direct impact in the received score, as part of the judging criteria. Therefore, wave selections is an important factor in competitive surfing and should be note by the coaches, indicating that these must combine the information of the choice of maneuver, technique, power of execution (15), and wave selection in their feedback to the athlete.

Practical Applications

The low cost and easy administration of the dRPE makes them readily accessible to surfers and coaches. Implementation of the dRPE in training routines allows surfers and coaches to quantify workloads during training sessions or competitions heats that are comparable with data derived from more expensive GPS devices. This may provide insight and knowledge in respect to modifying the conditioning and training regimes of the athletes. This is the first study to address the use of the dRPE for quantifying the surfers' workload; future researchers may use the findings of the current study to collect similar data in official competitions and heats. Future research should include different cohorts of competition spots and locations to describe the variability of the surfers' workload between various competitions or surfing locations.

Acknowledgments

The authors thank the Guipuzkoan Surfing Federation (GSF) and the Basque Country Surfing Federation (EHSF) for facilitating data collection and for the opportunity to perform this investigation. No financial assistance was provided for this study. Disclosure of funding received for this work from any of the following organizations: National Institutes of Health (NIH), Welcome Trust, Howard Hughes Medical Institute (HHMI), and other(s).

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Keywords:

global positioning system; score; rating of perceived exertion; heat load

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