Climbing-specific grip strength is regarded as a physiological key performance indicator for climbing ability and is the most examined performance factor in climbing research.1,2 Climbing-specific grip strength, however, covers a broad category of elements. Specific grip techniques of the hand used while climbing vary both with climbing discipline and the design and nature of the route.3–7 Furthermore, the type of muscle contractions in the grip techniques alter between concentric, eccentric, and isometric. Similarly, the velocity and duration of contractions vary. The term “grip strength” is, thus, a complex and multifaceted concept.
To date, different methods have been developed and refined over time to assess climbing-specific finger flexor strength.8 Testing climbing-specific maximal isometric finger strength by mass unloaded from a force sensor below a climber hanging on a rung above has shown acceptable test–retest reliability and a high criterion validity, and it is also an easily accessible method for use in a clinical setting.8,9
Although higher maximal strength in both open-handed and full-crimp gripping techniques has been established as predictive of climbing performance, other common grip techniques have been less examined.8 In addition, each climbing discipline likely requires specific, differentiated strength profiles, and thus, the importance of different types of finger strength in relation to climbing performance should preferably be evaluated separately for each climbing discipline.8 The primary aim of this study was to determine test–retest reliability and criterion validity of isometric finger strength testing of male boulderers in 6 distinct, commonly used grip techniques in relation to maximum nonflashI bouldering level.
Material and Method
Participants
In this cross-sectional study, we included participants recruited through online advertisement and at local climbing gyms in Sweden. We included participants who were over 15 years old and had completed 3 successful ascents on 3 different bouldering routes within the previous 3 months at an advanced level or higher, as classified by the International Rock Climbing and Research Association (IRCRA).10 This constituted a bouldering level of 17 on the IRCRA reporting scale (6B Font, V3 Vermin) in men and 15 on the IRCRA reporting scale (5 + Font, V1 Vermin) in women.10 Exclusion criteria were current pain and/or injury affecting the ability to participate in the study. Due to the small number of women recruited, resulting in insufficient power, this group (n = 16) was excluded from the analysis.
The study was approved by the Swedish Ethical Review Authority (Dnr 2020-03011), and all participants completed an informed, written consent to participate.
Demographics
We collected demographic data and highest self-reported bouldering performance through a custom-made questionnaire administered prior to testing and reviewed upon arrival at the test site. The questionnaire was based on the IRCRA position statement and included age, body mass, body height, sex, dominant hand, and finger pad size (distance from the palmar side of the distal interphalangeal joint to the fingertip, in centimeters, on the third digit of the dominant hand). In addition, we recorded information regarding predominant discipline, years of climbing, training, and competition frequency.10
Self-reported bouldering performance was evaluated by reporting of the highest level at which 3 nonflash boulder ascents had been completed in the last 3 months.
Testing Equipment and Grip Techniques
We tested 6 grip techniques for each participant: front 3 drag, half crimp, full crimp, 35° sloper, and 2 different pinch grips (Figure 1). The front 3 drag, half crimp, and sloper tests were conducted on a Beastmaker 1000 Series hangboard (tulipwood, Beastmaker Limited) lower lateral 20-mm edge with approximately 10 mm radius and the 35° sloper. Due to difficulties applying the closed crimp grip technique on the Beastmaker 1000 series hangboard as a consequence of its design, we performed the test of the closed crimp grip technique on a custom-made edge by Problemsolver hangboards (Ash, Problemsolver AB), designed to have corresponding properties and dimensions to the Beastmaker lower lateral edge. The Beastmaker 1000 Series hangboard and the custom-made edge by Problemsolver hangboards were affixed as seen in Figure 2. We evaluated the pinch grip on 2 wooden cubes (pinewood) with the measurements of 45 × 90- and 90 × 90-mm, custom-made by Problemsolver hangboards. To facilitate reproducibility of the pinch-testing method, the wooden cubes were attached to a rope hanging freely above the boulderer (Figure 3).
—The 6 different grip techniques tested, with description of the conditions in which each technique was exercised during testing.
Citation: International Journal of Sports Physiology and Performance 19, 3; 10.1123/ijspp.2023-0129
—Illustration of the required body positioning during all maximal isometric finger-strength tests. The elbow was positioned in full extension, with the wrist in neutral position and with shoulders and hips parallel in the frontal plane to the hangboard.
Citation: International Journal of Sports Physiology and Performance 19, 3; 10.1123/ijspp.2023-0129
—Illustration of the Beastmaker 1000 rungs (left), as well as the custom-made 20-mm edge (middle) and the 45/90-mm pinch grips (right).
Citation: International Journal of Sports Physiology and Performance 19, 3; 10.1123/ijspp.2023-0129
Assessment of Finger Strength
We instructed the participants to refrain from exhausting physical activity 48 hours before the testing session. In preparation of each testing session, we removed chalk build-up on the holds by gentle sanding with 120-grit sandpaper. Before testing, 15 to 20 minutes were allocated to self-administrated warm-up, using, although not limited to, the holds mounted overhead, allowing the participants to familiarize themselves with the holds. To avoid excessive warm-up resulting in pretest fatigue, we used no standardized warm up routine as preferred warm-up routines as well as fitness vary between individuals. Instead, we instructed participants to take their time and while avoiding fatigue, warm up to a level where they felt comfortable with applying maximal force in all grip techniques.
The participants performed all tests standing on a force plate with 200-Hz resolution from MuscleLab, and we registered the force using the MuscleLab software (version 10.4.37.4073, Ergotest Innovation A/S). Before testing each grip technique, we instructed participants regarding the grip techniques and mandatory hanging technique (Figures 1 and 2). The height of the force plate was, when needed, adjusted by elevating it on 2 height-adjustable boards. The participants were allowed to familiarize themselves with the hanging technique and specific hold and grip technique to be tested. Before commencing finger strength testing, we tested whether the participant could hang freely from one hand on a specific hold. If the participant could, or felt close to being able to hang freely, we added weight to the boulderers’ body mass, starting at 5 kg and adding 5 kg till the participant could no longer hang freely. The added weight plate was attached to a climber’s harness or weight belt around the participant’s waist and positioned between the knees, aligned with the participant’s center of gravity.
Commencing measurements, we instructed the participant to keep shoulders and hips parallel in the frontal plane to the hang board above and slowly lower themselves by bending the knees until the elbow straightened. From this position, the participant slowly transferred as much weight as possible onto the hold (Figure 2). The test was terminated when the participant felt that they had reached maximal effort or slipped off the hold. The participant had 7 seconds to achieve maximal effort. If any of the requirements of finger or body positioning was inadequate, the test was discarded, and the participant had to redo the attempt. Each grip technique was tested one hand at a time with 3 attempts for each hand. One attempt consisted of a completed unilateral hang on each hand. A 2-minute rest was mandatory between each attempt in the same grip technique. Between each grip technique, a 5-minute rest was mandatory to allow for more complete recovery.11 Participants were allowed to chalk up before each attempt, and the holds were cleansed of chalk build-up between each attempt, using a brush. We recorded the peak force unloaded from the force plate for each attempt, and the highest force reached in each grip technique for the right and left hand was used for analysis. A second test session was conducted for measurements of test–retest reliability between 24 hours and 1 week after the first test session. The test–retest was repeated using identical methodology as the first assessment of finger strength.
Statistical Methods
We used IBM SPSS Statistics for Mac (version 24) for demographic description of the data and performed statistical tests using the statistical analysis software SAS (version 9.4 for Windows, SAS Institute Inc). The level of significance was set at P < .05. In the analysis, we only included participants who had completed their hardest ascent in bouldering.
We presented categorical variables in relative number of occurrences, n (%). For demographic data, continuous normally distributed variables were presented with the mean (SD) and for continuous variables with skewed distribution, the median (interquartile range). The cut-off for skewness was set to 0.5.
For comparison of strength in grip techniques relative to body mass between ability groups, we grouped participants according to the IRCRA position statement.10,12 Fisher nonparametric permutation test was used for continuous variables. The CI for the mean difference between groups was based on Fisher nonparametric permutation test. We calculated the effect size using the absolute difference in mean divided by pooled SD. Cohen d was used for general characterizations of effect size.13 To examine criterion validity, we used univariable linear regression to examine the association (coefficient of determination, beta coefficient, and 95% CI) between maximal strength relative to body mass in each grip technique (strongest and weakest hand) in relation to highest nonflash bouldering grade in the last 3 months, according to IRCRA et al.10
To examine the relative importance of strength in each grip technique, we applied a stepwise multivariable linear regression model including all maximal isometric peak finger strength tests, using forward selection and backward elimination applied for each added variable. We set the inclusion and elimination boundary to P < .05. We used Wilcoxon signed-rank test to compare the mean difference between tests and retests and the Shrout–Fleiss reliability 2-way random-effects model to test the intraclass correlation coefficient (ICC) between tests and retests. We classified the ICC accordingly.14
Results
Demographics
We included 50 boulderers (16 women and 34 men) in the study. In the analysis, we included 32 male participants as 2 male participants had completed their most difficult ascent in disciplines other than bouldering, and female participants were excluded due to the low sample size, resulting in insufficient power in the analysis. Eleven participants were classified as advanced boulderers, and 21 were classified as elite or higher elite boulderers according to the IRCRA classification system. In the advanced group, the median age was 27 years (interquartile range 25; 35), and the median body mass index was 23 (21.6; 24). In the elite and higher elite group, the median age was 23 (22; 32), and median body mass index was 22.5 (21.9; 23.2) (Table 1).
Study Participant Demographics
| Bouldering level | Total, N = 32 | Advanced level, n = 11 | Elite and higher elite level, n = 21 |
|---|---|---|---|
| Age, y | 26.5 (22; 33) | 27 (25; 35) | 23 (22; 32) |
| Body mass, kg | 70.9 (66; 76) | 76 (64.5; 79) | 69 (66; 75) |
| Height, cm | 178.3 (6.4) | 179.4 (6) | 177.7 (6.7) |
| Body mass index | 22.6 (21.7; 23.6) | 23 (21.6; 24) | 22.5 (21.9; 23.2) |
| Pad size, cm | 2.7 (2.5; 2.8) | 2.7 (2.4; 2.9) | 2.7 (2.5; 2.8) |
| Years in climbing | 10 (4.5; 13) | 4 (2; 6) | 11 (9; 15) |
| Hours climbed per week | 9 (6.0; 12) | 6 (4.5; 12) | 9 (7; 14) |
Note: Pad size is the distance from the palmar side of the distal interphalangeal joint joint to the fingertip, in centimeters, on the third digit of the dominant hand. Continuous variables are presented as mean (SD) when normally distributed and as median (interquartile) when skewed.
The advanced group had been climbing for a median of 4 (2; 6) years, and the elite and higher elite group had been climbing actively for 11 years (9; 15). The advanced group had a weekly training volume of 6 hours (4.5; 12), and the elite group a weekly training volume of 9 hours (7; 14).
Assessment of Finger Strength
All grip techniques displayed the ability to discriminate between advanced and elite boulderers (P < .05; Table 2). Criterion validity for all grip techniques, as measured by the highest nonflash boulder grade during the last 3 months, ranged from R2 .26 to .58 (P < .001; Table 3). The half crimp technique for the strong hand displayed the highest ability to predict bouldering grade (R2 .58, beta 11.5; Table 3). Individual measurements of maximal isometric peak finger strength relative to body mass (in kilograms) in the half crimp position are shown in the scatter plot of Figure 4.
Grip Techniques’ Ability to Discriminate Between Different Levels of Boulderers, as Measured by Hardest Nonflash Ascent in the Last 3 Months
| Grip technique | Total, N = 32 | Advanced level, n = 11 | Elite and higher elite level, n = 21 | P | Difference between groups, mean (95% CI) |
|---|---|---|---|---|---|
| Front 3 drag—strong hand | 0.87 (0.13) (0.82; 0.92) | 0.77 (0.13) (0.68; 0.86) | 0.92 (0.10) (0.88; 0.97) | .0022 | −0.15 (−0.24 to −0.07) |
| Front 3 drag—weak hand | 0.82 (0.12) (0.77; 0.86) | 0.72 (0.12) (0.64; 0.80) | 0.87 (0.92) (0.83; 0.91) | .0008 | −0.15 (−0.23 to −0.07) |
| Half crimp—strong hand | 0.90 (0.15) (0.79; 1.00) | 0.78 (0.13) (0.69; 0.86) | 0.96 (0.11) (0.91; 1.01) | .0004 | −0.19 (−0.28 to −0.09) |
| Half crimp—weak hand | 0.84 (0.14) (0.80; 0.89) | 0.73 (0.11) (0.65; 0.80) | 0.91 (0.10) (0.86; 0.95) | .0002 | −0.18 (−0.26 to −0.10) |
| Closed crimp—strong hand | 0.93 (0.14) (0.88; 0.98) | 0.83 (0.13) (0.74; 0.91) | 0.98 (0.11) (0.93; 1.03) | .0022 | −0.16 (−0.25 to −0.07) |
| Closed crimp—weak hand | 0.88 (0.13) (0.83; 0.93) | 0.79 (0.12) (0.71; 0.88) | 0.93 (0.10) (0.88; 0.97) | .0040 | −0.13 (−0.22 to −0.05) |
| Sloper—strong hand | 0.86 (0.14) (0.81; 0.91) | 0.77 (0.12) (0.69; 0.85) | 0.91 (0.13) (0.85; 0.97) | .0050 | −0.14 (−0.25 to −0.05) |
| Sloper—weak hand | 0.82 (0.14) (0.77; 0.87) | 0.74 (0.13) (0.65; 0.83) | 0.87 (0.13) (0.81; 0.92) | .0098 | −0.13 (−0.24 to −0.04) |
| 45-mm pinch—strong hand | 0.40 (0.06) (0.38; 0.42) | 0.37 (0.04) (0.34; 0.40) | 0.42 (0.06) (0.39; 0.45) | .014 | −0.05 (−0.10 to −0.01) |
| 45-mm pinch—weak hand | 0.38 (0.06) (0.36; 0.40) | 0.34 (0.04) (0.32; 0.37) | 0.39 (0.06) (0.37; 0.42) | .010 | −0.05 (−0.09 to −0.01) |
| 90-mm pinch—strong hand | 0.47 (0.08) (0.44; 0.49) | 0.41 (0.05) (0.37; 0.44) | 0.49 (0.08) (0.46; 0.53) | .0046 | −0.08 (−0.13 to −0.03) |
| 90-mm pinch—weak hand | 0.42 (0.08) (0.39; 0.45) | 0.38 (0.06) (0.34; 0.42) | 0.44 (0.08) (0.41; 0.48) | .025 | −0.07 (−0.12 to −0.01) |
Note: Finger strength in the tested grip techniques is presented relative to body mass (in kilograms). Continuous variables are presented as mean (SD). CIs and interquartile are presented for all variables.
Criterion Validity for Each Grip Technique as Measured by Hardest Nonflash Ascension in the Last 3 Months
| Grip technique | Ranges of finger strength relative to body mass | Maximal IRCRA grade | Beta (95% CI) | P | R2 |
|---|---|---|---|---|---|
| Front 3 drag—strong hand | 0.6–<0.8 | 22.7 (1.9) | |||
| 0.8–<1.0 | 23.6 (1.6) | ||||
| 1.0–1.1 | 26.1 (1.6) | 11.3 (6.6 to 15.9) | <.0001 | .45 | |
| Front 3 drag—weak hand | 0.6–<0.8 | 22.4 (1.5) | |||
| 0.8–<0.9 | 24.4 (2.0) | ||||
| 0.9–1.1 | 25.8 (1.9) | 12.4 (7.6 to 17.2) | <.0001 | .48 | |
| Half crimp—strong hand | 0.6–<0.8 | 22.2 (1.3) | |||
| 0.8–<1.0 | 24.3 (1.7) | ||||
| 1.0–1.2 | 26.0 (1.8) | 11.5 (7.9 to 15.2) | <.0001 | .58 | |
| Half crimp—weak hand | 0.5–<0.8 | 22.6 (1.8) | |||
| 0.8–<0.9 | 24.4 (2.0) | ||||
| 0.9–1.1 | 25.7 (1.8) | 11.3 (6.9 to 15.7) | <.0001 | .48 | |
| Closed crimp—strong hand | 0.6–<0.9 | 22.8 (1.7) | |||
| 0.9–<1.0 | 24.0 (2.2) | ||||
| 1.0–1.3 | 25.9 (1.8) | 10.7 (6.2 to 15.2) | <.0001 | .44 | |
| Closed crimp—weak hand | 0.6–<0.8 | 23.1 (1.9) | |||
| 0.8–<1.0 | 24.1 (2.3) | ||||
| 1.0–1.2 | 25.4 (2.0) | 9.9 (4.5 to 15.3) | <.0007 | .32 | |
| Sloper—strong hand | 0.6–<0.8 | 23.0 (2.0) | |||
| 0.8–<0.9 | 24.1 (1.9) | ||||
| 0.9–1.2 | 25.6 (2.0) | 10.1 (5.7 to 14.6) | <.0001 | .42 | |
| Sloper—weak hand | 0.6–<0.7 | 22.5 (1.7) | |||
| 0.7–<0.9 | 24.5 (2.0) | ||||
| 0.9–1.2 | 25.6 (1.9) | 10.1 (5.6 to 14.7) | <.0001 | .41 | |
| 45-mm pinch—strong hand | 0.28–<0.38 | 23.0 (2.0) | |||
| 0.38–<0.42 | 23.5 (1.7) | ||||
| 0.42–0.55 | 26.1 (1.6) | 22.1 (10.6 to 33.5) | .0004 | .34 | |
| 45-mm pinch—weak hand | 0.28–<0.35 | 23.6 (2.4) | |||
| 0.35–<0.39 | 23.9 (1.8) | ||||
| 0.39–0.5 | 25.2 (2.3) | 21.7 (8.9 to 34.4) | .0016 | .29 | |
| 90-mm pinch—strong hand | 0.3–<0.4 | 22.9 (1.8) | |||
| 0.4–<0.5 | 23.8 (1.8) | ||||
| 0.5–0.6 | 26.5 (1.2) | 18.8 (10.8 to 26.8) | <.0001 | .44 | |
| 90-mm pinch—weak hand | 0.3–<0.4 | 23.8 (2.1) | |||
| 0.4–<0.5 | 23.2 (2.3) | ||||
| 0.5–0.6 | 26.1 (1.1) | 14.6 (5.3 to 23.9) | <.0031 | .26 |
Abbreviation: IRCRA, International Rock Climbing and Research Association. Note: All maximal isometric peak finger-strength tests are presented relative to body mass (in kilograms). Continuous variables are presented as mean (SD). Beta values are based on original numbers and not on stratified groups. Stratified groups are based on interquartile ranges and are solely of descriptive nature.
—Illustration of individual measurements of maximal isometric peak finger strength/body mass (in kilograms) in the half-crimp position for male boulderers. IRCRA indicates International Rock Climbing and Research Association.
Citation: International Journal of Sports Physiology and Performance 19, 3; 10.1123/ijspp.2023-0129
The beta value (11.5) of the half crimp technique showed that for every 10% increase in strength relative to body mass in this technique, a 1.15 increase in performance ability on the IRCRA scale could be expected. In the multivariable regression model, maximal strength in the half crimp technique of the strongest hand, together with maximal strength in the front 3 drag grip technique, explained 66% of the variance of nonflash bouldering grade during the last 3 months (Table 4). No other variable met the significance level of .05 for entry into the model.
Stepwise Multivariable Regression of Strength in the Different Grip Techniques in Relation to Maximal Nonflash Boulder Grade in the Last 3 Months
| Summary of stepwise selection | |||||||
|---|---|---|---|---|---|---|---|
| Step | Variable | Partial R2 | Model R2 | C(p) | F | Pr > F | Standard error |
| 1 | Half crimp—strong hand | .57 | .57 | 5.8 | 39.3 | <.0001 | 2.2 |
| Front 3 drag—weak hand | .09 | .66 | 0.9 | 7.4 | 0.01 | 2.5 | |
Note: All grip techniques of the strong and weak hand were included as possible predictors in the model.
All tests showed good to excellent test–retest reliability (ICC .78–.96), except for the front 3 drag on the left hand (ICC .605).15 ICC for each test is shown in Table 5.
Test–Retest Reliability for Each Grip Technique
| Grip technique | Mean difference between tests (CI) | Intraindividual SD | ICC |
|---|---|---|---|
| Front 3 drag—left hand | 0.044 (−0.305 to 0.393) | 0.126 | .605 |
| Front 3 drag—right hand | 0.007 (−0.099 to 0.113) | 0.037 | .932 |
| Half crimp—left hand | 0.004 (−0.108 to 0.116) | 0.039 | .942 |
| Half crimp—right hand | −0.001 (−0.094 to 0.091) | 0.032 | .963 |
| Closed crimp—left hand | 0.017 (−0.202 to 0.236) | 0.077 | .795 |
| Closed crimp—right | −0.006 (−0.131 to 0.119) | 0.044 | .930 |
| Sloper—left hand | 0.005 (−0.103 to 0.113) | 0.038 | .928 |
| Sloper—right hand | −0.020 (−0.144 to 0.104) | 0.046 | .841 |
| 45-mm pinch—left hand | 0.005 (−0.068 to 0.078) | 0.026 | .842 |
| 45-mm pinch—right hand | −0.002 (−0.092 to 0.088) | 0.031 | .788 |
| 90-mm pinch—left hand | 0.004 (−0.042 to 0.051) | 0.016 | .955 |
| 90-mm pinch—right hand | 0.012 (−0.063 to 0.088) | 0.028 | .881 |
Abbreviation: ICC, intraclass correlation coefficient. Note: All maximal isometric peak finger strength tests are presented relative to body mass (in kilograms). CIs are presented for mean differences between tests.
Discussion
In this study, we aimed to examine criterion validity and test–retest reliability for maximal isometric peak finger strength tests in 6 grip techniques for bouldering performance. The greatest association between nonflash bouldering performance and finger strength (relative to body mass) was found in the half crimp technique (R2 = .48 − .58), which is also supported by the multivariable regression model. Research in rock climbing performance has previously demonstrated the importance of maximal isometric finger strength as the most valid determinant of climbing performance.9,16–18 To date, a comprehensive understanding of the relative importance of maximal isometric strength in the major grip techniques has, however, been lacking. To our knowledge, this is the first study assessing unilateral maximal strength in multiple common grip techniques among male boulderers, shedding light on a significant topic.
Validity and Reliability
All tested grip techniques showed the ability to discriminate between advanced- and elite-level boulderers as well as to predict maximal grade bouldering performance. Interestingly, criterion validity was higher for the strong hand compared with the weak hand in all grip techniques except the front 3 drag grip technique. Based on the univariable and multivariable regressions, strength in the half crimp technique proved the most important determinant of bouldering performance for nonflash ascents in male climbers. Maximal strength in the front 3 drag position of the weak hand explained an additional 9% of the variance in the multivariable regression model.
The results of this study are comparable with those of Torr et al,17 which displayed that 5 seconds of unilateral maximal hangs in the half crimp/open handgrip technique (by preference) using a pulley system to progressively unload body mass over a series of test bouts until achieving maximal effort exhibited moderate associations to sport climbing and bouldering performance in intermediate to higher elite climbers (r = .42 − .50) while demonstrating excellent reliability (ICC .91–.98).17
A study by Balas et al,9 comparable in strength testing methodology, assessed the association between unilateral, peak isometric finger hang strength and climbing performance, using an electronic scale. The authors9 displayed associations for the open-hand and closed-crimp grip technique with climbing performance between 0.788 and 0.811, when relative to body mass, which is significantly higher than the associations in the front 3 drag and crimp grip technique in the present sample. Although the study included a significantly higher number of participants, the study by Balas et al9 also included participants at a wider range of climbing performance, ranging from lower grades to higher elite climbers. As finger strength is assumably the most limiting variable when climbing at a beginner level, this could explain these differences. An additional study by Michailov et al similarly displayed stronger associations with boulder ability (r = .815). The study used similar methodology during strength testing. Similarly to Balas et al,9 Michailov et al included male bouldering participants with a wider range of climbing performance (intermediate–elite).18
As we aimed to determine the importance of finger strength in different types of grip techniques in advanced and elite boulderers, the results should not be regarded in contradiction to Balas et al9 and Torr et al17 but, rather, as complementary. Although all grip techniques showed statistically significant criterion validity, the multivariable regression model displayed that half crimp in the strong hand, interestingly, determined 57% of the bouldering performance. However, subsequent addition of strength in the front 3 drag grip technique further increased the degree of determination by 9%. Strength in the half crimp technique, together with strength in the front 3 drag grip technique, collectively explained 66% of the variance in bouldering performance, leaving 34% of the variance unexplained by the included variables, demonstrating the multifaceted demands of rock climbing.
The intersession test–retest reliability of the grip techniques used in our study is high, with the exception of the front 3 drag technique of the left-hand side. A plausible explanation of the discrepancy between the ICC of the front 3 drag technique for the left- and the right-hand sides is that the front 3 drag technique on the left hand was the first of the grip techniques to be tested in the testing procedure. Insufficient habituation might have resulted in an initially greater variation in application of the instructed body positioning and technique compared with subsequent tests of grip techniques wherein more adequate habituation to instructed technique was achieved. Therefore, considering the high ICC of the front 3 drag technique on the right-hand side, it is safe to assume that the lower ICC of the left-hand side is not a true reflection of the reliability of the front 3 drag technique but, rather, a consequence of measurement error in the form of inadequate habituation to instructed body positioning and technique at the start of the testing procedure.
Grip-Strength Considerations
The ability to hold onto the smallest holds is one of the most limiting factors when it comes to achieving higher climbing ability.2 Biomechanically, the closed crimp is considered the strongest grip technique when grabbing smaller holds while climbing. Therefore, it might be hypothesized that strength in the closed crimp technique should be the most relevant factor when it comes to climbing ability compared with other gripping techniques. However, our results imply that the half crimp seems to play a greater role than expected in advanced to elite boulderers. This grip technique has not been tested in previous studies in relation to other grip techniques. It can be speculated that the participants’ training preferences/most preferred grip technique can be connected to the result. Empirically, half crimp is the technique most frequently used in both climbing and finger strength training for climbing, especially above beginner and intermediate levels. As the half crimp grip technique allows for greater mobility in the wrist and, therefore, the possibility of adapting the positioning of the fingers to maximize contact between holds and fingertips, the half crimp theoretically allows for greater modification to a variety of different hold types and body positions.5 This may explain its high relevance for climbing performance. In addition, the half crimp might be better suited for the vertical force vector tested in our study as the crimp technique has been shown to be more effective than openhanded grip techniques during application of an anteroposterior force vector.5
Across studies, heterogeneity in strength measurements of open handgrip techniques could be expected due to variations in hand anthropometrics. When distal phalanges of digits II–V are in contact with the hold, the degree of extension in digits III and IV is largely dependent on the length of digit V. A longer digit V allows greater extension in digits III and IV, whereas a shorter digit V will limit extension in digits III and IV, resulting in a grip technique more similar to a half crimp than an open hand grip technique. Force produced in the crimp and sloper grip techniques in elite climbers has been shown in descending order to be digit III and digit II, followed by digit IV and, finally, digit V, with digit IV producing higher forces in lower degrees of flexion.19 To avoid interstudy variability, using the front 3 drag technique to assess strength in an openhanded technique might, therefore, be recommended to reduce potential errors and overlap in finger strength measurements between grip techniques due to anthropometrics.
In addition, analyzing strength in the dominant hand is a common methodological approach when examining finger and hand strength. As climbing equally challenges strength in both hands, the concept of analyzing strength through the dominant hand might not be as specific. Instead, using the strong hand in analysis of validity might provide a more accurate analysis of the importance of finger strength for performance.
Limitations and Strengths
The sample size is to be considered a limitation of the study. Due to the limited sample of women, validity could not be analyzed in women. The results must also be interpreted with study group characteristics in mind. Older and adolescent boulderers, or boulderers at more modest levels of performance, may exhibit different test performance profiles. The moderate ability of the tested grip techniques to determine bouldering performance prove the need for more comprehensive approaches when examining key performance indicators, including additional variables other than maximal isometric finger strength, to further investigate the subject.
Strengths of the study include the comprehensive approach to bouldering-specific grip strengths, with clear distinction between grip techniques, thus minimizing overlap between the grip techniques. In addition, the well-stratified sample of advanced and elite boulderers provides results that limit potential confounding factors, providing clearer guidance of the importance of finger strength for a sample in which performance indicators are highly relevant.
Practical Applications
The result of our study highlights the importance of well-developed climbing-specific finger strength to perform at a higher level of bouldering. Measurement of specific maximal isometric finger strength through the presented method can be considered a reliable, sensitive, and easily quantifiable physiological performance indicator for male boulderers. The method provides an easily repeatable approach of measuring the finger strength of advanced and elite boulderers, with high precision and the capacity to differ between advanced and elite boulderers. Ranges of maximal strength relative to body mass in grip techniques common to climbing provide useful guidance in performance training for bouldering, potentially serving as an indicator of when increased maximal strength in specific grip techniques might be a reasonable focus in training. Based on our results, strength in the half crimp technique is the most important component of finger grip strength for male bouldering performance in advanced and elite boulderers.
Conclusion
Strength in the half-crimp technique proved the most important performance indicator in this sample, accounting for 57% of the variance in bouldering performance. The method presented in this study provides a reliable and valid framework for maximal isometric peak finger-strength testing in advanced and elite male boulderers.
Notes
A “flash” ascent of a route refers to a successful ascent in the first try, with prior knowledge or advice regarding a boulder problem.
Acknowledgments
We gratefully thank the Swedish Climbing Federation and its staff for its support in recruiting participants to the study. A special thanks to Sportrehab and its staff for generously giving us space to conduct the strength measurements. The results of the current study do not constitute endorsement of the product by the authors or the journal.
References
- 1.↑
Sanchez X, Torregrossa M, Woodman T, Jones G, Llewellyn DJ. Identification of parameters that predict sport climbing performance. Front Psychol. 2019;10:1294. doi:
- 2.↑
Saul D, Steinmetz G, Lehmann W, Schilling AF. Determinants for success in climbing: a systematic review. J Exerc Sci Fit. 2019;17(3):91–100. PubMed ID: 31193395 doi:
- 3.↑
Quaine F, Vigouroux L, Paclet F, Colloud F. The thumb during the crimp grip. Int J Sports Med. 2011;32(1):49–53. PubMed ID: 21086244 doi:
- 4.
Morenas Martin J, Del Campo VL, Leyton Roman M, Gomez-Valades Horrillo JM, Gomez Navarrete JS. Description of the finger mechanical load of climbers of different levels during different hand grips in sport climbing. J Sports Sci. 2013;31(15):1713–1721. PubMed ID: 23751129 doi:
- 5.↑
Amca AM, Vigouroux L, Aritan S, Berton E. Effect of hold depth and grip technique on maximal finger forces in rock climbing. J Sports Sci. 2012;30(7):669–677. PubMed ID: 22339482 doi:
- 6.
Schweizer A, Hudek R. Kinetics of crimp and slope grip in rock climbing. J Appl Biomech. 2011;27(2):116–121. PubMed ID: 21576719 doi:
- 7.↑
Vigouroux L, Quaine F, Labarre-Vila A, Moutet F. Estimation of finger muscle tendon tensions and pulley forces during specific sport-climbing grip techniques. J Biomech. 2006;39(14):2583–2592. PubMed ID: 16225880 doi:
- 8.↑
Stien N, Saeterbakken AH, Andersen V. Tests and procedures for measuring endurance, strength, and power in climbing—A mini-review. Front Sports Act Living. 2022;4:847447. PubMed ID: 35308594 doi:
- 9.↑
Balas J, Mrskoč J, Panáčková M, Nick D. Sport-specific finger flexor strength assessment using electronic scales in sport climbers. Sports Technol. 2014;7:151–158. doi:
- 10.↑
Draper N, et al. Comparative grading scales, statistical analyses, climber descriptors and ability grouping: international rock climbing research association position statement. Sports Technol. 2015;8(3–4):88–94. doi:
- 11.↑
de Salles BF, Simao R, Miranda F, Novaes Jda S, Lemos A, Willardson JM. Rest interval between sets in strength training. Sports Med. 2009;39(9):765–777. PubMed ID: 19691365 doi:
- 12.↑
Draper N, Dickson T, Blackwell G, et al. Self-reported ability assessment in rock climbing. J Sports Sci. 2011;29(8):851–858. PubMed ID: 21491325 doi:
- 14.↑
Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rater reliability. Psychol Bull. 1979;86(2):420–428. PubMed ID: 18839484 doi:
- 15.↑
Koo TK, Li MY. A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155–163. PubMed ID: 27330520 doi:
- 16.↑
Draper N, Giles D, Taylor N, et al. Performance assessment for rock climbers: the international rock climbing research association sport-specific test battery. Int J Sports Physiol Perform. 2021;16(9):1242–1252. PubMed ID: 33652414 doi:
- 17.↑
Torr O, Randall T, Knowles R, Giles D, Atkins S. Reliability and validity of a method for the assessment of sport rock climbers’ isometric finger strength. J Strength Cond Res. 2022;36(8):2277–2282. doi:
- 18.↑
Michailov ML, Balas J, Tanev SK, Andonov HS, Kodejska J, Brown L. Reliability and validity of finger strength and endurance measurements in rock climbing. Res Q Exerc Sport. 2018;89(2):246–254. PubMed ID: 29578838 doi:
- 19.↑
Quaine F, Vigouroux L, Martin L. Effect of simulated rock climbing finger postures on force sharing among the fingers. Clin Biomech. 2003;18(5):385–388. doi:
