Footwear in rock climbing: Current practice

Footwear in rock climbing: Current practice

The Foot 25 (2015) 152–158 Contents lists available at ScienceDirect The Foot journal homepage: www.elsevier.com/locate/foot Footwear in rock climb...

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The Foot 25 (2015) 152–158

Contents lists available at ScienceDirect

The Foot journal homepage: www.elsevier.com/locate/foot

Footwear in rock climbing: Current practice R.D. McHenry, G.P. Arnold, W. Wang, R.J. Abboud ∗ Institute of Motion Analysis & Research (IMAR), Department of Orthopaedic & Trauma Surgery, University of Dundee, TORT Centre, Ninewells Hospital & Medical School, Dundee DD1 9SY, Scotland, UK

h i g h l i g h t s • Rock climbers often wear ill-fitting and overly tight footwear. • Foot injury and deformity, including hallux valgus, is common in the group. • The extent of shoe-size reduction amongst rock climbers has been quantified for the first time, showing a mean reduction of almost 4 UK shoe sizes for rock climbing footwear.

• A shoe-size reduction was also found between an ideal fit and that of rock climber’s everyday footwear. • A greater than previously reported prevalence of foot pain during climbing activity is reported (91.07%).

a r t i c l e

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Article history: Received 7 April 2015 Received in revised form 30 June 2015 Accepted 1 July 2015 Keywords: Rock climbing Footwear Foot injury

a b s t r a c t Background: Many rock climbers wear ill-fitting and excessively tight footwear during activity. However, there is insufficient evidence of the extent or harms of this practice. Objectives: To investigate footwear use in rock climbers with a focus on issues surrounding fit. Methods: A cross-sectional study with active rock climbers of over one year of experience completing a survey on their activity and footwear. Additionally, the authors quantified foot and shoe lengths and sizes alongside demographic data. Results: Ill-fitting and excessively tight footwear was found in 55 out of 56 rock climbers. Foot pain during activity was also commonplace in 91% of the climbers. A mean size reduction of almost 4 UK shoe sizes was found between the climbers’ street shoe size and that of their climbing footwear using a calibrated foot/shoe ruler. There is an unfortunate association of climbers of higher abilities seeking a tighter shoe fit (p < 0.001). Conclusion: With the elucidation of footwear use amongst rock climbers, further investigation may aim to quantify its impact and seek a solution balancing climbing performance while mitigating foot injury. © 2015 Elsevier Ltd. All rights reserved.

1. Introduction

1.1. The climber’s foot

Rock climbing is an increasingly popular sport with a literature base primarily investigating injury, often with a focus on the upper limbs [1–4]. There is an unmet need for research into the impact of rock climbing footwear on the foot structure of rock climbers [5]. In particular there has been limited investigation into the effects of the common practice of wearing rock climbing footwear that is too small or unnaturally formed [6–10].

Existing literature on the climber’s foot has established that the majority of active rock climbers will have had some form of pain or injury to the foot or ankle while climbing [6–8]; alongside a finding that the percentage of injuries sustained increases with greater climbing skill [3]. Common foot deformities and injuries amongst rock climbers include pressure marks, subungal haematoma, splinter haemorrhage, cuts and bruises to the toes, dystrophic and infected nails, and a worrying prevalence of hallux valgus deformities [6–9]. However, there is suggestion of benefits of the sport to the longitudinal arch of participants’ feet [10]. Much of this injury has been linked to a pervasive culture amongst rock climbers to accept a degree of foot pain and discomfort in footwear to attain enhanced performance [6–10].

∗ Corresponding author. Tel.: +44 1382 383502; fax: +44 1382 383500. E-mail address: [email protected] (R.J. Abboud). http://dx.doi.org/10.1016/j.foot.2015.07.007 0958-2592/© 2015 Elsevier Ltd. All rights reserved.

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However, some of the problems associated with rock climbing footwear remain ill-defined and unpublicised. The dangers of excessively tight footwear may not be adequately realised by rock climbers, with a recent study of the epidemiology of rock climbing injuries making no mention of specific foot injury on self-reported questionnaires, despite evidence for its prevalence [4].

1.2. The climber’s shoe Despite this relative paucity of research into the problems of tight footwear, some effort has been concentrated on a solution. Van der Putten and Snijders’ [9] investigation into, and the development of, a better biomechanically adjusted climbing shoe asserted the critical importance of not only appropriate shoe design, but also correct sizing. The authors recognised the dichotomy of a good fit in climbing footwear between a shoe that is too small, causing foot injury and restricting toe extension, and one that is too big, giving difficulty when standing on small edges and slippage of the shoe on the foot. No study to date has comprehensively assessed the degree of size reduction in climbers footwear, though an average shoe-size reduction of 2.3 sizes is often quoted [6,7]. The relationship between incorrectly fitted footwear and foot deformity remains inadequately defined. A recent review of the literature surrounding hallux valgus deformity found only one reliable study of the link between footwear and hallux valgus, specifically highlighting lack of width as a factor in hallux valgus deformity development [11,12]. The same study also associated lack of shoe width with the presence of corns on toes and foot pain, and lack of length in footwear to lesser toe deformity. In addition, Harrison et al. [13] presented the difficulties encountered in the investigation of shoe size and the link to pathology. Nevertheless, case reports have shown that restrictive footwear has serious longterm clinical consequences that may only be revealed in later life [14]. Current recommendations warn against the wearing of excessively restrictive rock climbing shoes and for removal of shoes between successive climbs, although no study to date has assessed the scientific basis for the use of such restrictive footwear, nor have these recommendations been investigated [15]. However, more recent comment suggests much of this advice is ignored; excessively tight shoes remain commonplace [5].

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2. Methods 2.1. Participants Fifty-six adult rock climbers, 11 female and 45 male, with over one year of experience, were recruited at the Avertical World (AW) Climbing Centre. Mean age was 33.6 years (SD 11.66), mean height was 174.9 cm (8.61), mean weight was 73.6 kg (12.49), mean BMI was 24.0 (3.20) and mean years of climbing experience was 10.8 Years (11.21). Volunteers were given briefing on the aims and objectives of the study, and written consent was gained. The project was approved by the University Research Ethics Committee. 2.2. Study design Volunteers were recruited over 10 weekday evenings at the AW Climbing Centre. All of the climbers approached completed a questionnaire, with any queries or clarifications explained by the lead author. Participants were asked to provide background information on their activity levels, including their duration of climbing experience. The highest grades of rock climb that they had completed over a range of activities within the sport were also recorded. Participants were asked to give details of any foot pain or injury sustained through rock climbing. On completion of the questionnaire the length in millimetres of the participants’ feet in bipedal stance and climbing shoe length were recorded with a ‘Ritz Stick’ type device. The size stated on participants’ climbing shoes was noted. Climbing footwear was measured along its longest axis, from the most posterior point on the heel to the furthest point anteriorly, often found anteromedially in modern asymmetric climbing shoes. In more radical shoe designs involving a downturned forefoot, shoes are flattened along the longitudinal arch during measurement to account for the change in shape during use, Fig. 1 illustrates this method. Clinical photographs of each participant’s feet were taken as a record to identify any obvious foot abnormality. 2.3. A note on quantifying ability The comparison of different styles of climbing is a difficult one - though there is some consensus at how difficulties of routes in different disciplines of rock climbing interact. Efforts have been

Fig. 1. Figure illustrating the method of measuring the length of a climbing shoe.

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Fig. 2. The Rockfax Grade Table – illustrating the conversion between different grading systems.

made to give a true measure of each subject’s ability, using a system outlined below. Mean ability was classified using the French sport climbing grading system for bolt-protected outdoor routes. Where the subject’s maximum climbing ability was not seen in the bolt-protected outdoor routes graded with this system, an adjustment was made to equate the climber’s best performance to a similar difficulty in the French sport climbing grading system (Fig. 2). This was accomplished by comparing the relevant grades with widely available comparison charts [16]. If the maximum grade climbed by a participant fell within a wide band of French sport grades, the middle-most grade was selected. For example, if a climber’s maximum grade climbed was a traditionally-protected

climb of British E7, their maximum grade would be adjusted to the French sport grade of 7c+. Likewise, if the maximum grade climbed fell at the boundary between two French sport grades, this was represented as such. For example, a climber with the maximum achievement of bouldering 6B+, would be assigned an adjusted French sport grade of 7a+/7b. To determine an average ability of the cohort, each full French sport grade (ascending from 4 to 4+, 5, 5+, 6a, 6a+, 6b and so on) was assigned a linear rank, increasing with difficulty (for example, French sport grade of 4 would be assigned the rank 1, and grade 6b the rank 7). Where participants had been assigned a split grade they were assigned a rank between the closest full grades (for example, where a participant was found to have a maximum

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25 20 equency

French sport climbing grade of 7a+/7b, they were assigned a rank of 11.5). Using this adjusted maximum climbing ability, and assuming a linear relationship between true ability and each grade, the mean maximum climbing ability of participants was found to be approximately 7a+/7b.

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15 10

2.4. Statistics

5

The collected data was analysed using SPSS V.17.0 (SPSS Inc, Chicago, IL, USA) and Microsoft Excel 2010 (Microsoft Corporation, Redmond, WA, USA). Statistical significance was set to p < 0.05. Where correlation across the sample with normally distributed variables was under investigation, Pearson product-moment correlation coefficient was applied. If the variable was found to be non-normally distributed, Spearman’s rank correlation coefficient was applied. Paired-sample Student’s T-test analysed the various footwear sizing choices of rock climbers.

0 <90

90-95

95- 10 0

10 0-1 05

> 105

Climbing Shoe Exterior Length as a Percentage of Foot Length (%) Fig. 4. Exterior length of shoe as percentage of foot length and the frequencies at which they occur. Higher

Ability

3. Results 3.1. Foot pain Of the 56 participants, 51 (91.07%) reported foot pain while climbing, with 43 (76.79%) removing their shoes intermittently throughout activity to relieve this discomfort. The reported regularity of foot pain during activity is plotted in Fig. 3. No correlation was seen between the extent of shoe tightness and the regularity of foot pain during activity. Likewise, no link was found between the number of years climbing experience and the frequency of their foot pain.

Lower

85

100

105

110

15

11

30 25 20 15 10 5 0 Some of the time About half the time

Most of the time

Regularity of Foot Pain during Activity Fig. 3. Regularity of foot pain during activity.

All of the time

Frequency

Fifty five participants (98%) were found to be wearing excessively tight climbing footwear, i.e. a shoe that is shorter than the ideal shoe length by 1 UK size or an equivalent. Of the 55 participants, 41 (73.21%) were found to be wearing climbing shoes of shorter exterior length than that of their feet. The extent of this difference was found by subtracting the average length of the climber’s feet in bipedal stance from the average exterior length of their usual climbing shoes. These differences, plotted as shoe length as a percentage of foot length, and the frequencies at which they were observed are presented in Fig. 4. No significant relationship was seen between the climber’s years of experience in the sport and their shoe length as a percentage of their foot length. However, a strong negative correlation was seen between climbing ability and difference between climbing shoe length and foot length, with (rs(55) = −0.648, p < 0.001), this relationship is seen in Fig. 5.

equency

95

Fig. 5. Exterior length of shoe as a percentage of foot length against climber’s ability.

3.2. Footwear size

Never

90

Climbing Shoe Exterior Length as a Percentage of Foot Length (%)

8

4

0 -6.5

-6

-5.5

-5

-4.5 -4 -3.5 -3 -2.5 -2 Size Reduction (UK Sizes)

-1.5

-1

-0.5

0

Fig. 6. Shoe size reduction in climbing shoes and the frequencies at which they occur.

These relationships are reflected by an average climbing shoe length that is 0.71 cm (SD1.16) shorter than the climbers’ feet. Mean self-reported normal shoe size was rounded to a UK 8 (actual mean 8.31, SD2.27). However, by equating foot length to a calibrated standard for shoe size, an accurate mean normal shoe size for the group was rounded to UK 9 (actual mean 9.17, SD2.08), an average reduction of almost one size. A paired T-test between these values demonstrates significant difference (p < 0.001), confirming a tendency amongst climbers to wear poorly fitting ‘everyday’ footwear. A size for each climbing shoe based on a calibrated standard equating normal shoe length to normal shoe size was then devised. With this measure, the mean climbing shoe size was found to equate to a UK size 5 (actual mean 5.29, SD2.06) shoe, indicating a reduction of 4 UK sizes (actual mean reduction of 3.88) between the climbers’ actual shoe size, and the true UK size of their climbing footwear. Detail of the reduction in sizes between participants’ shoe size based on measurement and the UK shoe size of their climbing shoe based on standard measurements are shown in Fig. 6. An example of the length discrepancy between a typical climber’s foot,

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Fig. 7. Photograph of a climber’s left normal shoe, his foot, and climbing shoe.

The method used attempts to draw a broad scheme of defining ability, although may give slight bias to the hardest individual moves performed by the climber over the kinds of difficulty that may be encountered through either dangerous, or endurance, routes. This gives a system that proves useful when assessing factors, such as shoe fit, primarily associated with the ability to perform very difficult physical movements on small footholds, but may be less effective when other factors are under consideration.

14

Size Marked

11 8 6 3 0 20.0

22.5

25.0

27.5

30.0

Average exterior length of pair of shoes in centimetres

Fig. 8. Average exterior length climbers’ shoes and the size marked in UK sizes.

their normal footwear, and their climbing footwear is shown in Fig. 7. In the assessment of consistency of sizing between different shoe models, the average exterior length of each pair of shoes was compared to the size stated by the manufacturers (Fig. 8). Notable differences between exterior lengths of shoes of the same nominal size were recorded. A wide variety of foot injury was reported, with dorsal and plantar callus formation seen with almost all the climbers participating in this study. In addition broken or dystrophic nails, foot numbness, cuts, bruises, pressure marks and blisters were present in most cases. At least 10 of the participants suffer from hallux valgus, with bony deviation of the lateral foot also appearing commonly. Other injuries reported by participants included hallux rigidus, chronic achilles tendon pain, and persistent foot cramps. 4. Discussion 4.1. Participants The sample of 56 climbers including 11 female climbers (19.6%) in this study reflects previous studies reported in the literature and participation statistics [2,4]. The cohort of climbers surveyed is of a higher mean ability than the population of UK climbers as a whole [2]. 4.2. Quantifying ability Great lengths were pursued to accurately describe each participant’s true climbing ability. In a multi-faceted sport such as rock climbing, this inevitably becomes a difficult task, and one prone to error. With the breadth of activity within the sport, and a myriad of standards that may be held to define a ‘good climber’, the task may be compared to developing a scale by which both 100 m sprinters and world-class marathon runners could be accurately compared.

4.3. Foot pain Existing research has identified that many rock climbers experience foot pain or discomfort, linked to the widespread practice of wearing ill-fitting or excessively tight shoes during climbing activity [3,6]. This study confirms these findings, and reports a higher than previously reported prevalence of foot pain (91.07%), which may be attributable to the ill-fitting footwear commonly chosen for climbing activity. Many of the climbers surveyed in this study (76.79%) take steps to mitigate this pain through shoe removal, yet maintain the same footwear choices. We believe this finding, and that of the relative regularity with which this pain is endured, supports previous suggestion that there is a cultural acceptance of foot pain amongst the rock climbing community, in spite of obvious dangers to the foot structure. 4.4. Footwear size In the evaluation of foot and shoe length this study has added a record of absolute values for each of these variables. Using an assessment of shoe fit based solely on the length of the shoe and foot, we assessed a major factor determining fit. Nevertheless, many other factors, notably the interaction between foot and shoe width, are also key to correct fit and demand the attention of further research seeking to describe, or improve, shoe fit in rock climbers. With a record of absolute values for both shoe and foot length in rock climbers (in light of the unreliability of manufacturerdescribed sizing reported above) this study presents a clearer picture of the footwear choices of rock climbers. These figures show that the majority of climbers wear footwear of shorter lengths than appropriate, both outwith and particularly during activity. In addition, it is important to consider the discrepancy that will be seen between the interior dimensions of the shoe (those available to the foot when shod) and those exterior dimensions that may be easily measured. A combination of the shoe structure and sticky rubber sole of the climbing shoe may be expected to produce a shoe with the interior dimensions 0.5 cm and 1 cm smaller than the exterior dimensions described. As such, the amount of length available to the foot in the shod state will be less than the figures suggest.

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This further increases the apparent restriction of the climber’s foot within the shoe. While there are limitations in equating climbing shoe sizing to that of conventional street footwear, lacking evidence to the contrary, we must treat a correctly fitted street shoe as the ‘gold standard’ for foot health. With this in mind, a mean shoe size reduction of over 4 (with extremes of up to 6.5) shoe sizes during activity must give us considerable concern for rock climbers’ foot health. This assessment neglects the differences between the demands placed upon conventional and climbing footwear, particularly the lack of ‘unrolling’ required in climbing shoes, significantly altering the requirements of good fit. Nevertheless, this evidence of nearintolerable size reductions during activity presents an alarming reflection of footwear use in rock climbers. Perhaps equally worrying is the finding of incorrectly sized street shoes across the sample, with a mean reduction of almost one size conferring further risks to the climber’s foot. This gap may be due in part to a normalisation of tight footwear for those who spend time in climbing shoes, leading to a need to wear a reduced size in everyday shoes to maintain this fit. Alternatively, this finding may be a reflection of poor shoe size choices more generally, with shoes bought for many years without foot measurement neglecting any foot changes in the intervening period, or of an attitude amongst rock climbers that sees foot discomfort and pain as part of everyday routine. A strong negative correlation was seen between shoe length as a percentage of foot length and the ability of the climber. This may be attributed to a belief amongst rock climbers that a smaller shoe fit aids performance, with many accepting high degrees of foot pain in the pursuit of a tighter fit. Some elements of scientific credence have been lent to this view in the literature, emphasising the smaller moment arm associated with the flexion of toes in the climbing shoe [9]. However, the potential harms, both for performance (with the loss of toe extension comes a reduced surface contact on ‘sloping’ footholds), and foot health, must be considered in the selection of shoe fit. This tight fit results in high pressures on the foot, particularly at the heel and forefoot. Modern climbing shoe design, often with a highly tensioned heel unit and a narrow asymmetrical toe box, compounds the issue, necessitating a ‘crimping’ or clawing of the toes, with extension at the metatarsophalangeal joints and flexion at the interphalangeal joints. In addition, this study demonstrats extensive variation in the length of climbing footwear of the same nominal size (Fig. 8), for example showing a 2 cm variation in length between two models of shoe marked as size UK 9. The unreliability of size as a mark of fit considerably undermines the ability of the climber to make sound footwear choices, and for the researcher to investigate these choices. Further research may focus on developing a sizing structure that is acceptable to both climbers and manufacturers, allowing correctly fitting shoes regardless of the model chosen. 4.5. Foot injury In line with previous investigations, a wide range and prevalence of foot injury, deformity and discomfort was identified amongst rock climbers. Difficulties occurred in the accurate classification of each climber’s injury without specialist assessment. However, even by self-reported measures, foot injury is seen to be rife amongst climbers in varying degrees of severity. An example of rock climbers’ foot morphology is seen in Fig. 9. The quantification and description of common patterns of foot injury in rock climbers is clearly an area that could benefit from more research. The development of a grading system based on common foot injuries in rock climbing may allow investigation into the effect that wearing tight shoes has on climbers’ feet in a more

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Fig. 9. Details of the right heel and dorsal surface of a typical rock climber’s foot; (a) severe dorsal callus and deformed hallux IP joint, (b) Haglund’s deformity and severe callus, (c) dystrophic nails, (d) severe dorsal callus and deformed lateral toes IP joints.

structured way. Continued research may bring greater understanding not only to injury during rock climbing, but also the impacts of ill-fitting footwear more generally. 5. Conclusion This study has added new insights into the problems surrounding foot injury and footwear use in rock climbing. It has been shown that foot pain during rock climbing is both common and regular, and the extent to which climbers restrict their feet during activity has been quantified. It is clear that many climbers, particularly those of higher ability, choose shoes that are significantly smaller than their feet. Also demonstrated is a wide variation in the manufacturers sizing of climbing footwear, adding to the problems encountered by the climber wishing to purchase appropriately sized shoes. These practices inevitably lead to the wide range and high prevalence of foot pain and injury seen in participants in this study. Further work may focus on establishing the correct sizing and tolerances for safe and effective footwear in order to prevent the discomfort and injury described while maintaining performance characteristics. This, in addition to the introduction of consistent sizing, may empower the climber to choose the correct shoes. Acknowledgements Thanks to Mr Ian Christie for editing the manuscript and his help with illustrations. Special thanks to Mr Ian Richardson and Mr Simon Jenkins of Avertical World Climbing Centre, Dundee, for access to their facilities and their continued support and to Rockfax for their permission to use the grade conversion table. The project was internally funded by the University Institute of Motion Analysis and Research (IMAR).

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References [1] British Mountaineering Council. Annual report. Manchester: BMC; 2012. [2] British Mountaineering Council. Membership survey. Manchester: BMC; 2010. [3] Largiadder U, Oelz O. An analysis of overstrain injuries in rock climbing. Schweizerische Zeitschrift für Sportmedizin und Sporttraumatologie 1993;41(3):107–14. [4] Jones G, Asghar A, Lllewellyn D. The epidemiology of rock-climbing injuries. Br J Sports Med 2008;42:773–8. [5] Morrison A. Climbing shoes: is pain insane? The British Mountaineering Council; 2009. http://www.thebmc.co.uk/climbing-shoes-is-pain-insane [accessed 15.10.12]. [6] Killian R, Nishimoto G, Page J. Foot and ankle injuries related to rock climbing. The role of footwear. J Am Podiatr Med Assoc 1998;88(8): 365–74. [7] Buda R, Di Caprio F, Bedetti L, Mosca M, Giannini S. Foot overuse diseases in rock climbing: an epidemiologic study. J Am Podiatr Med Assoc 2013;103(2):113–20.

[8] Schöffl V, Winkelmann H. Fußdeformitäten bei Sportkletterern [Footdeformations in sportclimbers]. D Z Sportmed 1999;50:73–6. [9] van der Putten E, Snijders C. Shoe design for prevention of injuries in sport climbing. Appl Ergon 2001;32:379–87. ´ [10] Demczuk-Włodarczyk E, Biec´ E, Sipko T, Boerner E, Jasinski R. Assessment of morphological architecture of feet in rock-climbers. Biol Sport 2008;25:93–8. [11] Nix S, Vicenzino B, Collins N, Smith M. Characteristics of foot structure and footwear associated with hallux valgus: a systematic review. Osteoarthr Cartil 2012;20(10):1059–74. [12] Menz H, Morris M. Footwear characteristics and foot problems in older people. Gerontology 2005;51(5):346–51. [13] Harrison SJ, Cochrane L, Abboud RJ, Leese GP. Do patients with diabetes wear shoes of the correct size? Int J Clin Pract 2007;61(11):1900–4. [14] Abboud RJ. Relevant foot biomechanics. Curr Orthop 2002;16:165–79. [15] Morrison A, Schöffl VR. Physiological responses to rock climbing in young climbers. Br J Sports Med 2007;41:852–61. [16] Rockfax, Grade conversions, http://www.rockfax.com/publications/grades/ [accessed 29.07.14].