Surfing is performed in a dynamic environment (10) with challenging situations (21), which compel surfers to adapt to variable oceanic conditions while maintaining a high level of performance (9). Surfing competitions last from 20 to 40 minutes depending on the format of the competition, and surfers' activity is characterized by repeated bouts where balance and force development are required (20). During competition, the surfer's score is determined by commitment, the degree of difficulty of the wave being ridden and the characteristics of the maneuvers, such as speed and power (29). In this sense, the physical conditioning of the lower limbs, along with the surfers' anthropometric characteristics, has been shown to play an important role in surfer discrimination (12,23,26).
Specific anthropometric characteristics have been related to the competitive level of junior (12,27) and senior surfers (26). Previous research has observed that the inverse association between the height of the center of gravity above the base of support and stability (14) may mean that shorter surfers have an advantage in surfing performance (21). This could explain why competitive surfers tend to be shorter than the average age-matched sporting population (19,21). Furthermore, because of the maturation process senior surfers have been shown to be taller, heavier, and have a greater composite lean mass ratio (LMR) (body mass/∑7-site skinfold thickness) than young surfers (26). Therefore, considering that increased levels of body fat are inversely related to surfing performance (3) and the association between LMR and maturation (26), a study of anthropometric characteristics according to the competitive level should help to better understand the influence of these parameters on surfing performance.
Furthermore, strength and power abilities seem to play a role in surfing performance (27). Surfers competing in the World Championship Tour (WCT) performed higher 1 repetition maximum (1RM) than surfers competing in the World Qualifying Series (WQS) (26). Similarly, Tran et al. (27), observed higher vertical jump capacity (i.e., relative vertical jump peak force, vertical jump peak velocity, and vertical jump height) in selected Australian elite competitive male junior surfers in comparison with nonselected surfers. Considering that the combination of major and progressive maneuvers are key elements to maximize scoring potential (29) and that the lower limbs are ultimately responsible for riding the surfboard and making the maneuvers through the contact of the feet with the surfboard, it seemed of interest to look in more depth into the possible association between surfing performance and lower limb power characteristics. Nevertheless, even though differences in vertical jump capacity according to competitive level (i.e., Nonselected and selected for the National Junior Team) (27) and isometric midthigh pull test results (i.e., stronger and weaker) (24) have been previously determined, we have not found any study analyzing the differences in vertical jump and lower limb peak power, considering competitive level and ranking in competitive surfers. So, the main novelty of our study is that our surfers are competitive surfers, and second, the ranking position of the surfers is based on a real scale of competitive success, as all the participants take part in the competition where the ranking is obtained. Unfortunately, more research in this direction is needed to better understand the influence of power on surfing competitive level.
Therefore, the purpose of this study was twofold as follows: (a) to compare anthropometric characteristics, vertical jump capacity, and lower limb maximal peak power of competitive surfers according to their competitive level, and (b) to evaluate the association among competitive levels (i.e., ranking positions), anthropometric characteristics, vertical jump capacity, and maximal peak power performance. We hypothesized that surfers with a high rank would show greater peak power in the lower limbs and vertical jump capacity and lower-body fat levels.
Experimental Approach to the Problem
Surfers with a different competitive profile, either national or international, were tested on their lower limb power output, and their competitive results and ranking position were recorded. The participants were tested for anthropometric variables, vertical jump power, and lower limb peak power, using identical protocols, to determine the differences in lower limb power qualities among participants according to different levels and ranking positions.
Twenty competitive surfers (20.75 ± 7.83 years) participated in this study. The surfing league that they competed in was used as the criteria to classify them because there is not a clear delimitation across studies of the criteria for considering participants as professional or amateur surfers. Surfers competing in the former Association of Surfing Professionals, Kings of Groms and Big Wave World Tour were classified as international surfers (INT, n = 11, 23.00 ± 9.92 years), and participants competing in the Monster Energy Tour were classified as national surfers (NAT, n = 9, 18.00 ± 2.65 years). Surfers were also ranked according to the Monster Energy Tour classification league into 2 groups according to their overall classification. The surfers classified in the top 50 of the ranking were identified as RANK1–50 (n = 10, 23.00 ± 9.15 years), and the surfers classified in the 51st–100th positions of the ranking as RANK51–100 (n = 10, 18.50 ± 5.85 years). No significant differences in age between groups were obtained. Written informed consent was obtained from each of the participants after a detailed written and oral explanation of the potential risks and benefits resulting from their participation, and they knew that they had the option to voluntarily withdraw from the study at any time. For underage participants written informed consent was required from their parents or guardians. This investigation was performed in accordance with the Declaration of Helsinki (2013), met the ethical standards in Sport and Exercise Science Research (13) and was approved by the local institutional review board.
Participants were allowed to familiarize themselves with the equipment and testing procedures before performing the test battery. All tests were conducted on the same day, during 1 week in February in the following order: anthropometric characteristics, vertical jump, and peak power test. All participants were asked to follow their normal diet and refrain from intense exercise during the 48 hours before the tests. Participants performed a standardized warm-up before data collection.
Height was measured with a stadiometer (Holtain Ltd., Crymych, United Kingdom) fixed to the wall and recorded to the nearest 0.1 cm (8). Body weight was measured with an electronic scale to the nearest 0.1 kg (Fagor, BB-150; Fagor, Mondragon, Spain) immediately after voiding with participants wearing light indoor clothing and no shoes. Skinfold thickness (triceps, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh, and medial calf) was measured with a skinfold caliper (Holtain Ltd., Crymych, United Kingdom), as described previously (7), and the sum of 8 skinfolds (∑skinfolds) was determined.
Surfers were required to perform 5 counter movement jumps (CMJs) interspersed with 45 seconds recovery periods (18) followed by 5 squat jumps (SJs). The CMJ had to be performed with their hands on their hips during the entire jumping activity and only a minimal flexion of their trunk was permitted during the push-off phase (17). The maximal flexion of the knees during this phase was required to be approximately 90° (4). The SJ starting position was at a knee flexion of 90°. No counter movement was permitted in the SJs. Any jump that did not meet the considered requirements was excluded from the calculations and had to be repeated. Flight height was measured in the SJ and CMJ (Optojump Next; Microgate Polifemo, Bolzano, Italy). The intraclass correlation coefficient (ICC) range for the Optojump was 0.91–0.92 (22). Stretch-shortening cycle efficiency was assessed as the CMJ-SJ difference (5), and the elasticity index (EI) (4) was also measured as follows: . In addition to these jumps, participants performed a 15 seconds vertical CMJ test (CMJ15S) (7). The CMJ15S had to be performed as consecutive nonstop CMJs during a 15-second period. Participants were required to start when they were ready, and stop when the researchers told them to after the 15 seconds period. Flight time (FT) and contact time (CT) were measured using the Optojump Next (Microgate Polifemo). Power output (w/kg) was calculated as the average of all jumps performed in the CMJ15S as follows: , where g is the gravitational force.
Peak Power Test
To compare lower-body power, an incremental power test was conducted on each leg to determine maximum peak power (MPP, in w) for the left leg (MPPL) and right leg (MPPR). To establish the MPP, participants were seated on the leg extension machine with legs placed under the pad (feet pointed forward) and hands holding the sidebars; the exercise involved extending the leg from a retracted position adjacent to the seat to an extended position away from the seat. Participants were asked to perform an incremental power test with an encoder (Ergotech Consulting; T-Force, Murcia, Spain) transducer attached to measure force and velocity. The ICC range for the encoder was 0.91 for average power and 0.94 for peak power (2). Before the test, the participants were assessed on their 1RM on the leg extension machine. The incremental power test was started at 40% of subject's 1RM and increased by 10% in each trial (26). A 2–3 minutes rest was provided between trials, until a failed lift occurred, at this point, the weight successfully lifted in the previous lift was recorded as the subject's MPP. Also, MPP leg asymmetry was obtained in absolute (w) and percentage (%) values (28):
The results are presented as mean ± SD. All the variables were normal and satisfied the equality of variances according to the Kolmogorov-Smirnov and Levene tests, respectively. Only the maximum score for each test was included in the data analysis. Independent t-tests were used to determine whether any significant differences existed between the groups (i.e., INT vs. NAT or RANK1–50 vs. RANK51–100). Practical significance was assessed by calculating Cohen's d effect size (6). Effect sizes (d) of above 0.8, between 0.8 and 0.5, between 0.5 and 0.2, and lower than 0.2 were considered as large, moderate, small, and trivial, respectively. Pearson's product-moment correlation coefficient (r) was calculated to determine the relationships among the parameters obtained from the surfers' ranking position, anthropometric measurements, and performance characteristics. The magnitude of correlation between test measures 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 (15). Data analysis was performed using the Statistical Package for Social Sciences (version 20.0 for Windows; SPSS Inc., Chicago, IL, USA) for Windows. Statistical significance was set at p ≤ 0.05.
The results obtained in this study for the total sample and divided into INT and NAT are presented in Table 1. No significant differences were observed between the INT and NAT groups in the anthropometric variables (p > 0.05, d < 0.47, trivial to small), in the vertical jump (p > 0.05, d < 0.30, trivial to small), or in lower extremity power (p > 0.05, d < 0.63, trivial to moderate). However, although the differences were not significant (p > 0.05), the NAT group had practical higher levels (d = 1.36–1.65, large) of IE (%) and SJ-CMJ (cm) compared with the INT group (p > 0.05, d = 1.36–1.65, large).
The results of this study show that the RANK1–50 group had a lower biceps (p < 0.01, d = 2.30, large) and sum of skinfolds (p ≤ 0.05, d = 1.53, large) in comparison with the RANK51–100 group (Table 2), especially in the skinfolds of the lower extremities (Front thigh: p ≤ 0.05, d = 1.87, large; Medial calf: p < 0.01, d = 2.32, large). Vertical jump performance was higher in the RANK1–50 group in comparison with the RANK51–100 group in SJ (p < 0.01, d = −1.73, large), CMJ (p < 0.01, d = −1.64), and CMJ15S (p ≤ 0.05, d = −1.45, large). The MPPR (p > 0.05, d = −0.70, moderate) and MPPL (p ≤ 0.05, d = −0.89, large) were also higher in the RANK1–50 group (Table 2). However, although the differences were not significant (p > 0.05), the RANK51–100 group had practical higher values in SJ-CMJ (p > 0.05, d = 0.65, moderate) and IE (p > 0.05, d = 1.42, large).
Moderate to large significant correlations were obtained between the surfers' ranking positions and some skinfolds (Triceps: r = 0.450, p ≤ 0.05; Biceps: r = 0.580, p < 0.01; Front thigh: r = 0.558, p ≤ 0.05; Medial calf: r = 0.695, p < 0.01), the sum of skinfolds (r = 0.474, p ≤ 0.05), and vertical jump (r = −0.569/−0.676, p < 0.01) (Figure 1). However, no correlations between the ranking and EI or the MPP values (p > 0.05) were obtained.
The purposes of this study were to compare anthropometric characteristics, vertical jump capacity, and lower limb maximal peak power of competitive surfers according to the competitive level, and to evaluate the association among competitive levels (i.e., ranking positions), anthropometric characteristics, vertical jump capacity, and maximal peak power performance. The results of this study provide novel data demonstrating the relation between ranking position and lower-body power as measured by vertical jump capacity. We did not find differences between NAT and INT competitive surfers in the anthropometric characteristics, vertical jump, and peak power of the lower limbs, taking into account the ranking positions (i.e., RANK1–50 vs. RANK51–100). On the contrary, we did observe differences in lower limb skinfolds, vertical jumps (SJ, CMJ, and CMJ15S) and in lower limb power output (MPPR and MPPL).
Because of the importance in surfing of anthropometric (12,26,27) and lower limb strength/power characteristics (12,23,26), competitive level differences in anthropometric characteristics (12,26,27) and in physical performance (i.e., vertical jump or power output) (16,26,27) have been analyzed in previous studies, obtaining contradictory results. Some studies reported differences in anthropometric characteristics between different level surfers (12,26), although similar articles did not find any such differences (22,27). In the same way, while some studies suggested that professional surfers have higher lower limb power than amateur surfers (22,25), other studies concluded that differences do not exist between these variables at different competitive levels (1,11,27). Even though, in our study, we did not find differences between the NAT and INT groups in skinfolds, vertical jumps (SJ, CMJ, and CMJ15S), and maximal power output (MPPR and MPPL) of the lower limbs, we did find differences in relation to the ranking positions (i.e., RANK1–50 vs. RANK51–100). Regarding the anthropometric measurements, the RANK1–50 group showed significantly lower biceps (45.9%), front thigh (34.1%), medial calf (44.1%), and sum of skinfolds (30.77%) than surfers in RANK51–100 (Table 2). Furthermore, the RANK1–50 group showed better vertical jump and maximal lower limb power performance. We observed that RANK1–50 jumped significantly higher in the SJ (20.3%), CMJ (17.8%), and CMJ15S (20.1%), and had higher scores for EI (41.3%), MPPR (17.14%), and MPPL (18.73%) than RANK51–100 (Table 2). The contradictory results obtained in these studies, our study included, (i.e., INT-NAT or RANK1–50-RANK51–100), are probably because of the different definitions used to classify athletes as a function of their competitive level, as each study has used their particular one. The distribution of the surfers in a NAT or INT classification was made according to the surfer's competition region. Surfers who only compete in national championships, tours, or events were classified as NAT; and surfers competing in international championships, tours, or events, apart from the nationals, were classified as INT. Because competitive surfing is becoming more competitive and professional, some of the competitive surfers are managing to get sponsored in pursuance of building a professional career; most likely because the economic factor plays an important role in being able to participate in international events. This economic factor may explain, therefore, why there are not differences between NAT and INT surfers in competitive surfing. This study reveals that the fact that some surfers are competing in international level events and others only in national level events does not mean that INT classified surfers have better physical conditioning, in terms of the present analysis. Ranking showed differences between surfers' anthropometric characteristics and physical performance. This could be explained because the surfer with more power and better conditioning in the lower limbs is able to perform better on the surfboard (21), resulting in better competitive results, thus improving the surfer's position in the ranking. Hence, surfer's conditioning level seems to be a good discriminator to assess ranking position. These facts reveal the importance of physical conditioning, and therefore the importance of the surfer's physical training.
In addition, the results of this study show a positive relationship between the classification in the ranking with some skinfolds (r = 0.450/0.695, p ≤ 0.05), and the sum of skinfolds (r = 0.474, p ≤ 0.05) as described in other studies in which ranking positioning had a significant positive correlation with the sum of 6 skinfolds (6 skinfolds: r = 0.66, p < 0.035) (12). Also, surfers' ranking positions correlated negatively with vertical jumps (SJ, CMJ, and CMJ15S) (r = −0.569/−0.676, p < 0.01). Regarding these results, a lower sum of skinfolds seems to be positive for surfing performance, as body power development must be accompanied by low fat mass to optimize surfers' relative body strength (3,26), and having a better performance in the vertical jumps (i.e., SJ, CMJ, and CMJ15S) will also be positive for surfing performance, because of the use of lower-body power to perform maneuvers and remain on the board (3,21,24,25). However, in our study, we did not find a significant relationship between ranking and MPP. These results indicate that the maximum quadriceps power test may not be specific enough to assess the surfers' physical conditioning. The possible reason for these results is that, in our study, MPP was calculated in a sitting position quadriceps exercise. Taking into account the present findings, the vertical jump tests (SJ, CMJ, and CMJ15S) appear to be more accurate in discriminating performance level than the MPP quadriceps test for surfing performance. It would be interesting to analyze whether other more surf-specific lower limb tests would reveal differences in output between surfers from different competitive levels.
It stands to reason that better-ranked surfers will have a low fat mass and better physical condition. This article demonstrates that surfers with better physical conditioning will have better competitive results (without downplaying the technical aspects of surfing), and those results will be reflected in a better ranking position. In the case of lower limb power, that can be measured through vertical jump output, which shows a strong relation with surfers' ranking positions. Taken together, these data suggest the importance of physical training and the benefits of power and conditioning for surfing performance. Further research within surfing is needed to establish the importance and need for physical training for surfing performance at all levels. In reference to this study and findings, a training study examining the effects of lower-body power training will be the next step, as the current findings demonstrate the correlation between physical conditioning in the vertical jump and ranking position.
The present results indicate that the surfers' different levels do not seem to be a good discriminator of surfers' physical conditioning; however, ranking position clearly reflects the surfers' physical conditioning and may be an accurate indicator of their physical performance. Furthermore, surfers with a lower fat mass and greater lower limb performance, in the vertical jump, have better competitive outcomes. In consequence, this may indicate that surfing coaches should include lower limb power exercises in their training program on a daily basis and control the surfer's fat mass ratio to achieve better competitive results.
No financial assistance was provided for this study. The authors would like to thank all the surfing athletes and coaches for their participation in 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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