Movement or notational analysis provides objective data about sport and enhances scientific understanding of athletic performance (1). Notational analysis has been used extensively in team sports such as soccer and rugby, facilitating the development of sport-specific tests and training (8,17,20). Less research has been undertaken on individual-based sporting activities. Video analysis is useful in these sports because it is difficult to determine characteristics because movements can be spontaneous and novel during competition (5). For example, Mendez-Villanueva et al. (15) found professional surfing consisted of highly variable intermittent activity in response to the demands of the external environment or ocean. Competitive climbing also involves novel problems that are dictated by an external environment. There has been minimal research on climbing, in particular bouldering, and quantifying movement characteristics of the sport could enable the development of specific training programs and test protocols.
Sport climbing is an intermittent sport consisting of single attempts at climbing a route of a minimum 15-m length (21) that takes 2-7 minutes to climb (27). Several researchers have examined physiological responses to competitive climbing indicating decreased handgrip strength (∼22%) and endurance (57%) (24) and increased oxygen consumption (∼50 mL/kg−1/min−1) and blood lactate production (∼6 mmol/L−1) relative to baseline measurements (16,19). The moderate increases in oxygen uptake and lactate production could result from the trunk and upper limbs being the primary contributors to work compared to whole-body activities such as running (25). Although blood lactate accumulation is moderate, anaerobic energy provision is important because climbing predominately uses high-intensity isometric contractions in the upper limbs (4,26). For example, isometric strength and rate of force development in the hands and forearms have been identified as key performance indicators in climbing (4,22,23,27). A less researched area of competitive climbing is bouldering. Bouldering consists of problems approximately 4-m high with markedly overhanging surfaces compared to the longer routes of sport climbing. Consequently, the physiological requirements of these activities may be different; therefore, experimental findings from sport climbing research may have limited validity to the performance of bouldering.
The competition format of the Bouldering World Cup consists of a qualification round (6 problems) and semi-final and final rounds with 4 problems in each. The semi-finals and final are performed on the same day separated by a 2-hour rest period. A climber has 6 minutes to complete a problem with multiple attempts allowed and scoring based on the aggregate of successful ascents and number of attempts for all problems. Each problem is also separated by a standardized 6-minute rest period (21). The format of competition dictates an intermittent activity pattern, and anecdotal evidence indicates bouldering requires considerable strength and power in the fingers and forearms, with energy primarily derived from anaerobic sources (13,27). Determining activity patterns for intermittent activity is important because this process can establish movement characteristics and key components of sport performance (2), which can be used in the development of sport-specific training or tests (18). However, to the authors' knowledge, climbing time, recovery, and exercise-to-rest ratios have not been established in bouldering. Consequently, the aim of this study was to quantify the movement dynamics and key performance indicators in an elite bouldering competition.
Experimental Approach to the Problem
The design of this study was descriptive and involved examination of climbing problems in the final round of a national bouldering competition. Time-motion analysis was used to quantify the movement characteristics and exercise-to-recovery ratios of elite climbers during competition. An additional objective was determining the value of video analysis in quantifying movement demands in this relatively new competitive sport and for studies investigating strength and conditioning methods used in competitive climbing.
A convenience sample of 6 elite climbers, with a mean ± SD age and climbing experience of 28 ± 5 and 16 ± 5 years, respectively, was filmed during a national bouldering competition (Boulder UK, Blackburn, United Kingdom) 1 month after the start of the competitive season. Subjects were elite-level competitors in the British national team with several in the top-50 climbers in the International Federation of Sport Climbing rankings for the World Cup boulder series. Although the sample was not randomly selected, the climbers regularly compete internationally and are presumably representative of elite boulder climbers. All subjects provided informed consent and the study had ethical approval from our institution.
The competition consisted of 5 novel climbing problems with 6 minutes to complete each problem. Problems were separated by standardized rest intervals of 6 minutes (Figure 1). The third and fifth problems were filmed as an unobstructed view of the climbers could be obtained. Two Panasonic NV-MX500 cameras (Panasonic Ltd, United Kingdom) operating at 50 Hz were used to film the competition from start to finish. A total of 6 climbers attempting 2 problems were captured, providing 12 climbing performances for analysis. Movements were analyzed from video footage using SwingerPro v2.0 software (Kandle Software, United Kingdom). Footage was classified as viewing time (time observing a problem prior to an attempt), number of attempts per problem, attempt time (duration from last body part leaving the ground to successful completion, or final contact with the wall), recovery time (time between end of an attempt and start of next attempt), climbing time (sum of attempt durations per problem), hand contact time with climbing hold, and reach time between holds. Movements were also classified as static (no discernable movement in pelvic girdle) and dynamic (4). Data for left and right hands were combined to give total time for contact with holds and time between holds.
Reproducibility of results obtained was established assessing the intratester reliability. Six of the 12 problems were analyzed twice by the same researcher. Reliability was determined using coefficient of variation (CV), as described by Hopkins (12). The mean ± SD were calculated using SPSS v13.0 (SPSS, Chicago, IL, USA) for number of attempts per problem, viewing time (seconds), attempt time (seconds), recovery time (seconds), hand contact time (seconds), climbing time (seconds) and reach time (seconds), static time (seconds), and dynamic time (seconds). Exercise-to-recovery ratios (seconds) were also calculated for the climbing problems (climbing time:recovery time) and forearm activity (hand contact time:reach time).
The CV with the 95% confidence interval (CI) for each variable was as follows: viewing time, 0.9% (95% CI: 0.6-2.3%); attempt time, 0.7% (95% CI: 0.4-1.9%); recovery time, 1.1% (95% CI: 0.7-2.7%); hand contact time, 2.0% (95% CI: 1.3-5.0 %); climbing time, 0.9% (95% CI: 0.6-2.3%); static time, 3.3% (95% CI: 2.0-9.9%); dynamic time, 3.2 (95% CI: 1.9-8.2%); and reach time, 21.2% (95% CI: 14.1-68.1%). The higher CV for reach time compared to other variables is a result of the considerably shorter times for this variable (0.127 s; 95% CI: 0.084-0.409 s) and the sampling frequency of the camera (25 Hz). Consequently, differences between the test and retest data for reach time produced larger variation in this measure compared to other variables.
Climbers spent 75.3 ± 25.4 seconds viewing a problem before an initial attempt, and a successful ascent took 39.5 ± 4.1-seconds. Table 1 shows the average characteristics of the climbing problems analyzed. Climbers attempted a problem ∼3 times taking ∼30 seconds with ∼115 seconds of recovery between attempts (Table 1). During an attempt, climbers typically gripped a handhold for ∼8 seconds with ∼0.6 second recovery reaching between holds (Table 1). Overall total climbing time per problem was ∼74 seconds. During each attempt the total time spent moving was 22.3 seconds and time spent holding static body positions was 7.5 seconds (Table 1). The exercise-to-recovery ratio during a 6-minute climbing period was ∼1:3.8 overall and ∼13:1 for activity in the finger flexors while attempting a problem (Figure 2).
The physical demands of bouldering were found to be substantially different to research findings on sport climbing (4). In the bouldering competition, there were shorter bouts of activity (30 seconds vs. 2-7 minutes); decreased static periods (25% vs. 38%), and more attempts allowed to ascend a problem (multiple vs. single) than sport climbing (4). The shorter bouts of activity probably reflect the smaller climbing distances in bouldering, but the reasons for the decreased static times are less clear. Steeper routes during difficult sport climbing result in significantly faster climbing speeds and greater blood lactate accumulation than less steep routes (7). Research on climbing surfaces (19,25) also found hold type, patterning, and steepness of the climbing surface can influence energy cost. Perhaps in our study, the steeply overhanging routes (up to 45 degrees beyond vertical) with a limited number of small-sized handholds caused competitors to spend minimum time on each hold and move rapidly in an attempt to conserve energy. Possible evidence for this strategy is the greater amount of time spent in motion during bouldering compared to sport climbing, indicating a more dynamic style of climbing in bouldering. The nature of the problems analyzed, which were short and steeply overhanging, and the necessity for multiple attempts by some elite competitors indicates bouldering requires a high level of skill and physical fitness. This supports the belief among climbers that bouldering represents the physically and technically most intense discipline of the sport with strength being central to bouldering performance.
The overall exercise to recovery ratio during a 6-minute climbing period was ∼1:4, which is similar to intermittent sports such as tennis (6) and rugby (9) and more favorable than the arm paddling-to-rest ratio of 1:1.25 observed in surfing (15). However, comparisons with these sports are not valid as a result of the high level of muscle activity in the forearms, which had an exercise-to-recovery ratio of ∼13:1 during a bouldering problem. It is also unlikely traditional measures of exercise intensity such as heart rate would relate directly to climbing performance because of the small muscle mass utilized and the isometric nature of activity in the upper limbs (4,19,25). Consequently, a more ecologically valid approach is to focus on the periods of high-intensity activity in the forearms observed during bouldering, which concurs with sport climbing research that highlighted the critical role of strength and endurance in fingers/forearms in performance (4,22,27). For example, research on sport climbers found trained rock climbers have significantly greater isometric forearm strength (14,22) and muscular endurance in response to repeated isometric contractions (10,22) than sedentary individuals. The enhanced performance in climbers is proposed to be from specific adaptations such as desensitization of efferent nerves; reduced metabolite accumulation; and a greater vasodilator response during recovery, which improves the performance of intermittent isometric muscle contractions (10,14,22). However, because forearm exercise-to-recovery ratios in the sport climbing studies equated to ∼3:1 seconds, they do not compare well to the 13:1 seconds observed in this study, which would allow minimal reperfusion of muscle tissue, and therefore recovery, between relatively long duration isometric muscular contractions (3,24). As a result of substantial differences in activity patterns between bouldering and sport climbing competition, it is unclear whether similar physiological responses and adaptations occur in bouldering athletes. Consequently, future research could examine training adaptations and physiological responses of bouldering athletes to competition.
There has been no research on the determinants of success in bouldering. Research on sport climbing suggests a high rate of force development in the forearms is critical to performance (27), and our observation of a very high exercise:recovery indicates forearm strength and power are important in bouldering performance. However, more studies are needed to determine the relationships between strength and power measures and climbing performance. This area of research could provide vital information about climbing performance and the physiological requirements of bouldering. For example, climbing literature and websites recommend the use of specifically designed apparatus such as fingerboards or campus boards, which focus on the development of strength, power and endurance in the fingers and upper limbs (11,13). Nevertheless, no study has examined the effectiveness of such devices or training methods, which typically use interval training and plyometric techniques. Strategy also appears to be an important part in successful ascents in bouldering competition. Anecdotal evidence from our study indicates successful competitors typically completed a problem after 1-2 attempts. In contrast, less successful athletes made multiple attempts before selecting a similar movement pattern as successful climbers. Goddard and Neumann (11) suggested successful sport climbers were faster at identifying the optimal route for ascent than less successful athletes. Future research with a larger sample size could investigate time-motion and strategic differences between successful and nonsuccessful attempts by climbers in bouldering competitions.
Analysis of video footage found bouldering consisted of repeated high-intensity efforts in the forearms that were separated by minimal rest periods. Strength and conditioning professionals can use the observed exercise-to-recovery ratio in the design and implementation of sport-specific training programs to replicate activity patterns observed during World Cup-level competitive bouldering. The steep terrain of competitive bouldering requires strength and power in the upper limbs and torso, specifically in the finger flexors. The rate of force development in the fingers also needs to be highly developed to maximize the ability to rapidly grasp holds successfully. Additionally, the results of this study suggest finger-strength endurance is probably important to sustain the high level of forearm muscle activity in bouldering. Climbing training texts commonly recommend 8 to 10 second contractions for specific finger training, which is probably a suitable contraction duration. However, observations from this study suggest this type of contraction needs to be repeated with minimal rest periods a number of times to adequately stimulate specific patterns of muscular activity to develop endurance.
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