Why Climbers Should Care about Contact Strength | Contact Strength Pt. 2
Hooper’s Beta Ep. 98
INTRO
Special thanks to The Wall Climbing Gym for allowing us to film at their facility! Check them out using the links in the description.
In the last video we establish what contact strength refers to in a scientific sense. And if you know the definition of contact strength, it should be kind of obvious why it’s important for climbers. But in this video, I want to move past the “common sense” reasons and see what the research has to say, because I found some of it to be quite interesting and even a bit surprising. We’re also going to talk about the huge elephant in the room, which is how contact strength in the real world might not be quite as simple as it appears in research. So cinch down those shoes and chalk those sweaty tips, ‘cause we’re about to send it!
CONTACT STRENGTH IS CORRELATED WITH CLIMBING ABILITY
ARTICLE I
First, let’s look at a short excerpt from Levernier G et al in their paper: “Four Weeks of Finger Grip Training Increases the Rate of Force Development and the Maximal Force in Elite and Top World-Ranking Climbers.”
If you couldn’t tell from the title, the researchers found that specific finger training increased the contact strength of elite climbers. They concluded that because the window of time climbers have to develop force on a hold is so small, “...increasing the RFD is, therefore, a crucial way to increase performance.” This conclusion is just the researchers’ opinion, but it aligns with the SAID principle.
The SAID principle says that each sport imposes unique demands on the body, so to improve at that sport, you should practice the moves that impose those demands. You want Specific Adaptations to Imposed Demands. With climbing, there are often moves where you need to develop a lot of force in a short amount of time. So, according to SAID, you should train in a way that increases your rate of force development.
ARTICLE II
Next we have an article titled: “Rate of force development and maximal force: reliability and difference between non-climbers, skilled and international climbers.” Here, the researchers took various measurements related to finger RFD within each group of climbers, which they categorized as “non-climbers” (climbing less than 5b), “skilled climbers” (climbing 7c-8a), and “international climbers” (climbing 8b or higher).
They showed that the higher skill levels had higher finger RFD than the lower levels. Specifically, the differences were as high as 34% between non-climbers and skilled climbers, 45% between skilled and international climbers, and 57% between international and non-climbers.
So right off the bat, this article is showing a pretty clear correlation between how high the climbers’ RFD was and how hard they climb. But as we should all know, correlation does not necessarily mean causation. The researchers do seem to believe that there may be some causation, though, stating that increasing RFD can increase “...climbing efficiency, especially in movement, such as the dyno or dynamic movement.” To be clear, this claim is the researchers’ opinion, but it once again aligns with the SAID principle.
Finally, the article concludes that for climbs that involve developing near-max force in a short amount of time, “... RFD of the finger flexor in isometric contraction is a reliable and discriminating variable… and could be used in monitoring training.”
So in summary, not only does this article show that there is a difference in contact strength between climbers of different skill levels, it suggests that increasing contact strength may improve your climbing with certain moves and that measuring RFD is a useful tool in monitoring training progress.
ARTICLE III
The next article we will look at is titled “Upper body rate of force development and maximal strength discriminates performance levels in sport climbing.” Just based on the title alone this one sounds juicy!
The researchers showed that “elite” climbers had higher RFD than the “intermediate” and “advanced” climbers. How they determined “elite,” “intermediate,” and “advanced” is a little bit complicated, so check the table below if you want to see exactly what they mean.
In the article, they conclude that “RFD may...be a key factor for predicting climbing performance, and has discriminated between skilled and international performance levels...” So contact strength could play a crucial role in someone’s climbing ability. Sounds pretty similar to the last article, right?
It’s important to note the research also found the elite group of climbers could produce higher peak force than the other climbers as well. However, when the researchers normalized the RFD values to account for this, the RFD of the elite climbers was still higher than everyone else.
Essentially, this article suggests contact strength is a crucial aspect of climbing performance and is not simply a byproduct of peak strength.
Counterpoint - ARTICLE IV
So far, the research we’ve looked at argues for a strong link between contact strength and climbing performance. However, is there any research to counter this?
Not much. One article titled “Reliability and Validity of Finger Strength and Endurance Measurements in Rock Climbing” did find their RFD measurements to be unreliable. This article did not compare RFD to climbing skill, though, and they used a different method of measurement than the other articles, making it hard to compare.
Overall, the evidence seems strongly in favor of contact strength’s link to overall performance. But performance is not the only area contact strength can affect.
CONTACT STRENGTH PROTECTS AND HEALS YOU
According to research by Levernier et al, higher RFD can help protect joints, particularly during explosive force production moments. In a sense, the higher your RFD, the faster your body can respond to maintain proper alignment of joints and possibly prevent poor adaptations of surrounding tissues. If you are unable to generate force in your fingers quickly enough, your tissue may elongate, your joints may move into less than ideal positions, and you may find yourself in a more injury prone position.
Along the same lines, training contact strength can also be an important aspect of returning from an injury. It can retrain the neurological processes that may be limiting you in your return to climbing, and it will help you build confidence in your tissue so that you can climb without hesitation and reduce the risk of another injury. Since I’m a PT, that is a major win for contact strength in my books!
SO SHOULD EVERYONE TRAIN CONTACT STRENGTH? (NO.)
Up to this point, we’ve cited a lot of interesting and even impressive evidence about contact strength. It’s closely correlated to climbing performance, it can help protect you from injury, it can help you heal… Well, shoot! Sounds like everyone should train contact strength, right?
Wrong! The benefits of contact strength do not apply equally to all climbers.
Contact strength for performance gains
The second research article we looked at said there were significant differences in contact strength when comparing elite climbers to advanced and intermediate climbers. However, that research also says that no significant differences were found between the intermediate and advanced climbers, concluding that: “...RFD may not be a crucial component for climbing performance before reaching the more demanding grades.”
Now, exactly why that is, the research doesn't say. However, if I had to guess, I'd say that since climbing at lower grades generally involves bigger holds and less dynamic moves compared to advanced climbs, it seems reasonable that contact strength would only start to play a crucial role at higher levels of climbing.
So that’s strike one for contact strength if you’re not pushing into higher grades.
Contact strength strength for protecting joints
What about the protective benefits? Those apply to everyone, right? Not necessarily, because again, lower level climbing typically does not involve movement that relies heavily on contact strength, so RFD’s protective benefits are mainly relegated to higher level climbers. Lower level climbers should be more concerned with building up a solid foundation of technique and strength before worrying about explosive power. Like, you shouldn’t be trying to jump to a 10mm edge if you can’t hang from it statically in the first place.
So that’s another strike for contact strength if you’re trying to protect your fingers at lower climbing levels.
Contact strength for injury recovery
How about the healing powers of contact strength? Can this be applied to all skill levels? Well, once again, no, though it does probably have a broader range than the other aspects of contact strength. However, it will still not have a huge impact on lower level climbers, around V4-5 and below.
Contact strength for bouldering vs sport climbing
Finally, what about boulderers vs sport climbers? Everyone knows boulders generally involve more powerful, explosive movement than long sport routes. In fact, 2013 research by Fanchini et al revealed that the peak RFD during a task of isometric finger flexion is 36.73% higher in boulderers than in lead climbers. Boulderers have higher contact strength than sport climbers! Does that mean only boulderers should worry about contact strength?
Unfortunately there’s no research that I know to answer that for us; I can only offer my opinion on this one. I think contact strength is more important for boulderers than sport climbers just by the very nature of the two different styles: explosive vs endurance. However, I don’t think sport climbers should ignore contact strength. The fact that many sport climbers use bouldering as a form of training may be evidence that higher contact strength does help on sport routes. On the other hand, because endurance is paramount in sport climbing, contact strength should likely not be a sport climber’s main focus.
So who should and shouldn’t train contact strength?
Bringing it all together, who exactly should and shouldn’t be concerned with contact strength? It’s not so simple to answer, but my advice is this: focus on building the best foundation of strength and technique you possibly can above all else. If you’re a boulderer pushing grades around V9 and above, you likely have this solid foundation, and thus contact strength training should probably be high on your priority list. For sport climbers, contact strength may also be a great tool to help you break through higher grades. For everyone else, contact strength may still be useful, but in the more limited sense of building stability into joints and/or recovering from an injury, and therefore should almost certainly not be your primary training focus. Beyond that, more research is needed before I can give more specific recommendations, so until then you’ll need to assess your own strengths and weaknesses to determine if contact strength is something you should focus on.
Whew, okay, that was a lot of info, but there’s one last thing we need to talk about before finishing up, and it’s kind of a big one, because you might think it flies in the face of all the research we’ve seen on contact strength thus far. As it turns out, contact strength in real life, outside of the lab, on real rock (or plastic) is not nearly as simple as RFD.
REAL WORLD CONTACT STRENGTH IS MORE COMPLEX THAN RFD
Contact strength in a scientific sense fits into this nice, tidy box known as finger RFD. It is purely the rate of force development in your fingers. But things aren’t so tidy in the real world, because in the real world you’re not sitting in a lab squeezing a device that measures RFD. You’re on a rock, chucking your body to a crimp you’ve never touched before, which just now is getting blasted by the hot sun, and maybe the landing is less than ideal, and maybe you don’t trust your spotter as much as you’d like, and maybe that finger injury you got six months ago is still in your head a little bit, and maybe you only slept 4 hours last night, etc. etc. In the real world, your ability to latch a hold “on contact” is not nearly as simple as RFD.
Practical (or “functional) contact strength diagram courtesy of The Power Company
The Power Company actually developed an awesome diagram to help visualize this concept, which they kindly provided for us to use in this video. The diagram shows that, in real world scenarios, strength and RFD is just one third of the equation, with technical ability and mental state being equally important. These three elements combine into what we will call “functional-” or “practical contact strength.”
Interestingly, the diagram also shows what can happen if you’re lacking functional contact strength, meaning you’re missing one of the three key elements. High RFD but weak mental state? You probably won’t believe in yourself and may fail due to low commitment. High RFD but bad technique? You probably lack coordination and may fail due to poor timing. This is a powerful diagram that truly shows the complexity of climbing and the fact that functional contact strength is not just a matter of RFD. Having the best RFD in the world means nothing if you can’t use it effectively on the rock.
Does this mean that everything else we've talked about regarding RFD is completely useless? Not at all! It is simply important to understand that outside of research, functional contact strength is a multifaceted skill that is deeply entwined with other aspects of climbing, which makes it one of the most complex but also most important skills to master. Understanding the nuances of functional contact strength will therefore help you make more informed decisions in your training and could ultimately determine your success as a climber.
CONCLUSION
Speaking of training, that’s what we’ll be talking about in the next video, the finale of this contact strength series. Specifically, we'll be showing you the various ways you can increase your contact strength as well as a full routine you can follow, so be sure to keep an eye out for that!
As for this video, remember these key points:
RFD has been shown by research to be predictive of climbing ability at higher skill levels
For some climbers, training RFD can help protect joints and heal injuries
RFD is not something every climber should be obsessed with
Functional contact strength relies just as much on technique and mental state as it does on RFD
And that’s it! If you liked this video please consider giving it a thumbs up, and until next time: train your friends to watch Hooper’s Beta, climb their projects while they’re distracted, send them a text from the top saying it was soft, aaaand repeat. But this time, make sure they subscribe.
Disclaimer:
As always, exercises are to be performed assuming your own risk and should not be done if you feel you are at risk for injury. See a medical professional if you have concerns before starting new exercises.
Written and Produced by Jason Hooper (PT, DPT, OCS, SCS, CAFS) and Emile Modesitt
IG: @hoopersbetaofficial
RESEARCH
Title
Upper body rate of force development and maximal strength discriminates performance levels in sport climbing.
Citation
Stien N, Vereide VA, Saeterbakken AH, Hermans E, Shaw MP, Andersen V. Upper body rate of force development and maximal strength discriminates performance levels in sport climbing. PLoS One. 2021 Mar 26;16(3):e0249353. doi: 10.1371/journal.pone.0249353. PMID: 33770128; PMCID: PMC7997018.
Key Takeaways
Moreover, in previous studies examining climbers, the strength and rate of force development (RFD) of the finger flexors has also discriminated between climbing performance levels [8] and disciplines
RFD is defined as the rate of the rise in force during isometric contractions, and has been used to quantify the ability to generate force rapidly
When climbing harder routes, the smaller holds and more difficult moves cause a need for more force to be exerted in a shorter time window to avoid falling off the route. RFD may, therefore, be a key factor for predicting climbing performance [4,5,8], and has discriminated between skilled and international performance levels when calculated using longer time periods
In one recent study [20], RFD was measured using a hand dynamometer, which have been shown to be less valid than specific tests (e.g., using climbing-specific holds and common climbing-positions
Conversely, Fanchini et al. [16] and Michailov et al. [19] used climbing-specific holds but isolated the finger flexors, excluding the arm- and back muscles from the testing. This might reduce the validity as, when climbing, the fingers are only responsible for maintaining contact with the holds whilst the vertical propulsive force of the climber is produced mainly by other prime movers (i.e., elbow flexors and shoulder extensors).
only two studies [18,22] have assessed the RFD of the entire pulling- apparatus (finger-, arm-, shoulder- and back-muscles) in one exercise (isometric pull-ups on a climbing-specific hold).
However, the authors compared climbers of different disciplines rather than performance levels.
absolute RFD (RFD100%; calculated from the onset of force to peak force
the shorter time periods (50–250 ms) could be associated with the explosive strength required for hard and dynamic climbing moves
Finally, it has been suggested that RFD data should be normalized (RFD relative to maximal force) to highlight whether or not differences in RFD are caused by a difference in maximal strength alone
The elite climbers produced higher RFD than the intermediate group at RFD100 (p 0.032) and RFD150 (p = 0.040), and higher RFD than the advanced group at RFD50 (p = 0.032) and RFD100
The elite group produced higher peak force output than the intermediate (ES = 1.77, p < 0.001) and advanced groups
In line with the primary hypothesis, the elite climbers produced higher RFD than the intermediate and advanced climbers. Conversely, no significant differences were found between the intermediate and advanced climbers.
Based on these findings, RFD may not be a crucial component for climbing performance before reaching the more demanding grades (> 24 IRCRA).
>24 =
> V9
=/> 7C
=/> 5.13c
=/> 8a+
The higher RFD produced by the elite climbers was accompanied by a notably higher peak force output than the other groups
Importantly, the RFD in the elite group was still greater than in the intermediate and advanced groups following normalization. Hence, the higher peak force alone did not cause the differences in RFD
However, it should be noted that the ES for the differences were reduced following normalization, suggesting that a meaningful portion of the differences in RFD is caused by the higher peak force output in the elite group.
Since advanced and intermediate climbers possess less climbing-specific strength of the finger flexors than the elites, performing a maximal-effort contraction using the shallow rung might limit the RFD substantially
One potential explanation could be that maximal strength accounts for less of the difference than neurological adaptations to years of attempting hard routes that require rapid force production [28]. In contrast to the absolute measures, the relative measures produced both lower CV values and more distinct between-groups differences, especially when examining the longer durations from the onset of force. As previously speculated [8], the maximal number of muscle fibers recruited while exerting maximal force is likely more reproducible than the time taken to recruit the fibers. As large variations between individuals’ times to reach peak force were observed in this (150 to 730 ms) and previous studies (~ 400 to 1000 ms) [8,18,22], using relative time periods should be the preferred method when examining the entire pulling-apparatus of climbers. For example, if an individual uses . 500 ms to reach peak force, the longest absolute time period (250 ms) would still represent the earlier phase of the force curve. Hence, relative time periods could be more functionally applicable than the traditional division of early and late phases [28] in tasks typically requiring longer than 250 ms to reach peak force
Examining the remaining relative (RFD50%—RFD100%) and absolute measures ((RFD100—RFD250), the intermediate and advanced climbers produced notably higher CV values (16.9– 30.1%) than the elite group (8.9–19.7%). These findings are in agreement with those of Levernier and Laffaye [8] who proposed that increasing skill level could be associated with an improved ability to reproduce similar force outputs across several attempts.
More climbing experience probably also produces a more efficient recruitment of the available motor units [34], thereby allowing for a more rapid force production across attempts.
Importantly, only male climbers were included in this study and the findings might not necessarily be generalizable to female climbers at the same level.
Furthermore, no familiarization session was performed as it was expected that experienced climbers would be able to perform the test adequately.
Title
Four Weeks of Finger Grip Training Increases the Rate of Force Development and the Maximal Force in Elite and Top World-Ranking Climbers
Citation
Levernier G, Laffaye G. Four Weeks of Finger Grip Training Increases the Rate of Force Development and the Maximal Force in Elite and Top World-Ranking Climbers. J Strength Cond Res. 2019 Sep;33(9):2471-2480. doi: 10.1519/JSC.0000000000002230. PMID: 28945641.
Key Takeaways
The training program was designed in conjunction with the French national team’s coaches and was repeated 3 times a week for 4 weeks. The other 3 training sessions involved regular exercises. Finally, the protocol did not change the frequency of training for both groups
Each climber observed a 2-day resting period before each test to avoid the effect of fatigue caused by earlier climbing sessions.
Subjects stood with 1 hand on the dynamometer. The angle between the arm and the chest was 208 in the sagittal plane and the angle between the arm and the forearm was set to 908. During the test, the subjects were advised not to move. The other arm stayed still along the body. Three different holds were selected (i.e., the slope crimp, half crimp, and full F1 crimp, Figure 1). These brought into play the flexor digitorum profundus (FDP) muscle and the flexor digitorum superficialis (FDS) muscle as the main muscles
The climbers were in a standing position, hanging from a personalized small hold (slats ranging from 25 mm to 6 mm off the mark 1808) (rue des dolmens, 46,220 Prayssac) and HRT (Mladost 4, 1715 Sofia, Bulgaria) with 1 hand. They had to hold on as long as possible without AU8 making contact between the foot and the ground, before falling with a 1208 angle between the arm and the forearm
The size and the grip of the hold were chosen individually in such a way that athletes could not stay in 1 hold for more than 6 seconds.
To limit the risk of injury, climbers warmed up their upper limbs with suspensions that used a large degree of prehension
In addition, if pain occurred during the exercise, they immediately had to stop.
This exercise was repeated for both hands in both conditions (slope and half crimps), with the training plane detailed in Table 1.
The training session lasted about 45 minutes.
The instructions were to “hold the device as strongly as you can and as fast as possible”
When focusing RFD in regard with expertise, results show an increase of the values of ICC with skill level.
Concerning the averaged RFD,mean coefficients of variation decrease from 17.78% for averaged conditions in non-climbers to 12.40% in international climbers. This decreasing value of CV with skill level could be explained by the ability to reproduce a stable pattern of force over time is related to training status, including the ability to recruit motor units quickly with a high level of neural drive
Indeed, the ratio of strength-to-body weight has been shown to be a determining factor of climbing ability
To the best of our knowledge, only Amca’s study with experienced climbers compared the values between these 3 grip techniques, revealing that climbers develop more force (+11%) in the full crimp (546.2 6 40.9 N) compared with the half crimp (490.1 6 37.4 N) and the slope crimp (+21%); (435.7 6 41.6 N)
Moreover, a recent study (30) has shown that using the thumb during a hold produces an increase in the force of finger flexor of 12% (442 6 42.9 N without thumb vs. 494 6 68.8 N with thumb during the full crimp
Amca et al. (2) recorded during the full crimp a tension of 254.8 N on the A2 pulley, whereas the A4 pulley received 220.9 N, for an external force of 95.6
On the contrary, in the slope crimp the tension was much lower (57.4 N for the A4 and 8.1 N for the A2 for the same external force)
According to Schweizer (32) in the full crimp position, at 25% of maximum strength, the A2 pulley received 3 times as much force applied on the fingers.
These data suggest that for 505 N, which was developed by the climber of our study in the finger grip, the pressure of pulleys A2 and A4 received an overload that could damage this passive anatomic structure. Thus, it seems more reasonable to use the half crimp and the slope crimp in training rather than the full crimp to avoid injury.
Methodological studies have suggested that focusing only on the RFD peak is not a relevant method because it only takes into account a part of the curve, which is highly sensitive to variability and sudden changes
Rather, it is more accurate to investigate the evolution of force as a function of a given time
Fanchini and White (14) showed that boulderers are able to develop more strength at a faster rate than lead climbers.
Our results show a significant increase in RFD200 ms for the training group for the 3 conditions of crimps (half, slope, and full). A 32% gain for the slope crimp, a 27.5% gain for the half crimp, and a 28% for the full crimp was recorded, whereas no change was recorded for the control group, with changes of—3% for the half crimp and +6% for the full crimp.
According to the literature on RFD changes with training, a gain in the early part of the force-time curve is due to changes in the neural control of muscular contraction.
Indeed, the activation of the muscle during a rapid and explosive contraction is mainly determined by the discharge of motor units, i.e., the neural factor (1). This discharge occurs at the start of the contraction and is decisive in the first 100–200 ms (34). The time for the experimental group to reach the maximal force in our study before training was 2.62 6 0.36 seconds. As the typical time needed during a bouldering event will always be shorter than the time needed to achieve the maximal force, increasing the RFD is, therefore, a crucial way to increase performance.
The change of RFD200 ms is due to an increase in the motor unit discharge and the contractile impulse, as suggested by Aagaard et al. (1). A gain later in the force-time curve, i.e., in the second part of the RFD, is linked closely to changes in the tendon-muscle coupling and to the contractile properties of the muscle, which increase later in the RFD curve
specific training performed by climbers is primarily impacted by the neural factor and by a probable increase in the discharge of the motor units. Therefore, a 4-week training program is sufficient to increase the force and RFD for the finger flexor for both elite and top world-ranking boulderers.
On the other hand, the training did not have an effect on the absolute RFD95%. The literature of RFD gain with training highlights that a gain on absolute RFD of the force-time curve is a combination of changes in the neural factor in the early phase and changes in the musculo-tendinous structure.
The fact that there is no effect on the RFD95% tells us that a 4-week training had probably no impact on the structural factors (i.e., the muscle architecture, cross-sectional area, and type fibers II) (3), but had an important impact on the neural factor, more particularly on the increase of the discharges of the motor units, as suggested by the gain obtained during the first 200 ms
Our study suggests that it is not necessary to work specifically on the full crimp grip to increase the force in this position; rather, working with the half crimp or the slope crimp grip can result in an increase in finger flexor force and rate of force for all grips.
Title
Rate of force development and maximal force: reliability and difference between non-climbers, skilled and international climbers
Citation
Levernier G, Laffaye G. Rate of force development and maximal force: reliability and difference between non-climbers, skilled and international climbers. Sports Biomech. 2021 Jun;20(4):495-506. doi: 10.1080/14763141.2019.1584236. Epub 2019 Apr 30. PMID: 31038051.
Key Takeaways
Fanchini et al. (2013) revealed that the peak of RFD during a task of isometric flexor of fingers is 36.73% higher in boulderers than in lead climbers
Another study reveals 16.70% higher performance obtained between elite and skilled climbers during an arm jump test, and 23.30% between skilled and novice climbers
Explosive force is of great importance in climbing and is defined as ‘the capacity to increase contractile force from a low or resting level as quickly as possible’
Elite climbers having 22.19% greater finger grip strength than skilled climbers who have 44.85% greater strength than novices
Climbers have very little time to grip strongly during these dynamic movements. This ability to develop a high level of force in a short time, that is, the rate of force development (RFD),
Fanchini et al. (2013) revealed that the peak of RFD during a task of isometric flexor of fingers is 36.73% higher in boulderers than in lead climbers
Thirty-one participants (12 international, 10 skilled and 9 non-climbers) were divided
(kind of weak still)
The aim was to analyse both RFD and maximal force (Fmax) and
Concerning the averaged RFD,mean coefficients of variation decrease from 17.78% for averaged conditions in non-climbers to 12.40% in international climbers. This decreasing value of CV with skill level could be explained by the ability to reproduce a stable pattern of force over time is related to training status, including the ability to recruit motor units quickly with a high level of neural drive
Moreover, this observation has a great impact especially when considering the functional importance of explosive force production in a wide variety of situations, such as to stabilise joints quickly to prevent falling or to maintain or adjust incorrect posture or balance.
Indeed, postural regulation in a short time is a key moment in climbing and involves neural processes such as sensory feedback and reflex, and is a highly adaptive strategy in preventing falls.
RFD100ms reveals a difference of 11.61% between international and skilled, 37.11% between skilled and non-climbers, and 44.41% between international and non-climbers. This part of the curve during the isometric task is influenced by neural drive
Furthermore, differences were observed in RFD200ms for all conditions: 24.51% between international and skilled, 34.04% between non-climbers and skilled, and 50.21% between international and non-climbers. Andersen & Aagaard
RFD between 150 and 250 ms is highly dependent on either the contractile properties of the muscle-tendon unit, such as cross-section area and neural drive, or a combination of both.
For RFD95%, a 45.18% difference between international and skilled, and 57.05% difference between international and non-climbers has been observed, meaning that international climbers would be able to reach 95% of Fmax more quickly than the others.
This two-times greater value found in international climbers compared to skilled climbers and non-climbers reveals their high level of adaptation in a wide variety of motions (fast and strong such as the ‘dyno’ movement or explosive movement, including postural or reflex adaptation and slower movements) compared to skilled climbers.
To conclude, RFD of the finger flexor in isometric contraction is a reliable and discriminating variable for climbing at 200 ms and at 95% of maximal force, and could be used in monitoring training.
Moreover, this parameter is able to discriminate skill level, as shown by the difference recorded between international and skilled, and skilled and non-climbers.
This implies for trainer that (i) designing workout for climbers based on holding as quick and as strong as possible is a good way to increase their finger rate of force development and consequently their climbing efficiency, especially in movement, such as the dyno or dynamic movements
recording the rate of force development at 200 ms is a good way to monitor a climber during training session, to assess the effect of a specific workout procedure on the way he produces the force or to compare values between different climbers.
The results reveal a high reliability for international climbers for the RFD, especially for the RFD200ms, suggesting that this variable could be used with a good accuracy for intra or inter subject comparison for training purpose. Moreover, this parameter is able to discriminate skill level, as shown by the difference recorded between international and skilled, and skilled and non-climbers.