0195-9131/92/2401-0144$3.00/0 MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Copyright 10 1992 by the American College of sports Medicine Vol. 24, No.1 Printed In U.S.A. LETTERS TO THE EDITOR-IN-CHIEF Editor's Note: Drs. Robbins and Gouw hav e chosen to raise the issue of the conflict of interest policies of the Journal and imply that the Journal should police letters written to the Editor-in-Chief. In the Informa tion for A uthors section of this issue of the Journal, the " conflict of i nterest" regarding published peer reviewed manuscripts has been addressed after receiving editorial board approv al and reflects a y ear-long rev iew of the policy. I reject Drs. Robbins and Gouw' s expectation that the Editor-in-Chief should impose this policy on letters to the editor. Historically, I have had to respond to a letter of complaint from Robbins and Gouw c onc erni ng one of their rejected manusc ripts. I n this complaint they a lso raised t he issue of c onflic t of in te rest by t he rev iew ers, as being the reason for the rejecti on of the ir manus cript, even though they w ere bli nd as to whom the rev ie wers were. Neither Drs. F re deri ck or C av anagh were reviewers on the re jected manusc ript. Furthermore, I rev iew ed their conc erns regarding t he ir manusc ript a nd found thei r charges of conflict of i ntere st t o be unf ounded. Clearly, these two l etters need to be r ead with a critical ey e to the sci ence bei ng dis cuss ed, and one needs to ref rain from bein g draw n into pers onal differe nce s. I c an assur e the reader s that the se two le tters will be the only ones publis hed o n the issues raised by Drs. Frederick and Cavanagh. Dear Editor-in-Chief: Dr. Steven Robbins has been republishing the same editorial seasoned with a pinch of new data for the last several years, and we are distressed to see y et another appearance in MSSE CMSSE 23:2 17, 1991). Dr. Robbins' main contention is that sport shoes affect the pattern of movement in a way that is unsafe. He presents data showing the effect of shoe sole materials on the mechanics of mov ement. Although Robbins wishes to extrapolate his data to actual running, his results are collected in a laboratory setting that involves contrived quasi-static movements and atypical limb postures rather than actual studies of runni ng mechanics. Further t o the poin t. Dr. Robbins' arguments re st heavily on the notion that informati on from cutaneous receptors are the only data that the body uses to monitor potentially damaging ;)trC ;);)CT5.his assertion is untenable and unproven. These facts combine d with the inappropriate kinetics used in Robbins' c xpcr ime nte conspires to make his results of limite d use in an understanding of running mecnamcs, or any other vlaorous athletic movement. Some runner snectnc technical Ilmitat ions we o bserved of which we fed y our reade rs should be aware. The spec ification of me chanical inputs in units of kg. crr r ? is misle ading. This is presumably the pressure in the authors' pneumatic actuators and is certainly not the pressure applied to any part of the body . To q uote these figures in the abst ract is meanin gless since the result of s uch an input is s pecifi c to t he re searcher' s apparatus. Thi s confusion seems to persist as the authors go on t o ex trapolate about possible vertical loads in r unni ng of 1.03 kg- cm" . T he pla ntar pressures duri ng actual run ning are at least 10 time s this v alue when measured on the bare foo t. T here is also some thing peculiar about the straight lines in Figure 4 and the das hed ext rapolations into load ra nges "s ee n in runners." The opening line of the discus sion is a blatant misstatement: "This experiment relates pla ntar lo ad during locomotion and jump ing and plantar discomfort w hen shod and unshod." It does nothing of the ki nd. Despite the limited usefulness of his data, researcbers like us, who study footwear biomechanics, ar e generally intrigued by many of Dr. Robbi ns ob serv ations about footwear-induced kinematic changes, bUI we s trongly disagree w ith his as se rtion tha t sport shoes hav e been shown to be unsafe, or less injurious than barefoot runnmg. It is impor ta nt to point out that his conclucion that wear ing ehoee i s " unsafe" is not base d on hi s own data, but is largely bncsd on ~ selective and rather c areless reading of the literature on me ernuermotoav oroveruse injuries in sport. F urthermore, Robbins bla tant ly miscites sev eral biomec hanica l st udies as supporti ng his 144 LETTERS TO THE EDITOR-IN-CHIEF contention that sport shoes are unsafe. No data are presented nor are any conclusions drawn. in any of the biomechanical studies cited by Robbins on the question of the safety of sport shoes. Dr. Robbins misrepresentation of the literature he cites is almost universal. A few of many examples: Robbin s cites Casperson et a l. (Med. Sci. Sports Exerc. 16:113, 1984) vs Marti et al. (Am. J. Sports Med. 16:285-294, 1988) to show a trend toward an increase in running injuries over the y ears, when in fact these studies cover overlapping time periods. Casperson's work (a very brief abstract that did not mention footwear) was published in 1984 and covers participants in a 1983 race. And, although the Marti research Dr. Robbins cites in support of his contention that shoes are uns afe was published in 1988, in fact, the surv ey was done in 1984 and was based on running injuries experienced during 1983-84. Further to the point, Marti' s research presents no data to show that shoes are unsafe, but he did find a statistically signific ant "preventive effect" from the use of shoe inserts-a point that clearly contradicts Robbins' assertions, but which he conveniently overlooks. Dr. Robbins further cites Marti as showing that runners who wear more expensive shoes (>$40) are more frequently injured, but Marti c learly points out that this is an " incorrect" conclusion. Only 2.7% of his sample w ore shoes under $40 in cost, raising the suspicion that the finding of fewer injuries in this small group is an artifact due to age and income differences (i.e., Marti reports that runners wearing these less expensive shoes tended to be young people and therefore more free of injury ). This kind of inat tention to detail and a willingness on Dr. Robbins part to overlook evidence that does not support his point of view is a thread that runs through this paper and his other recent publications. This is not an acceptable practice, and we believ e we would have hoped that such careless and irresponsible science would have been uncovered during the review process. Furthermore, it is our opinion that the title of Dr. Official Journal of the American College of Sports Medicine 145 Robbins' article was misleading and should not have gone unchallenged during the rev iew pro cess. He refers to athle tic shoes in the title as "unsafe." His report, however, has nothing 10 do with safety, has little to do with athletic shoes, and presents no data that can be interpreted as even indirectly supporting s uch a conclusion. No original data on sports shoe safety are presented, only data on artificial motor behaviors that hav e not been shown to occur in actual running and which have not been shown to be unsafe by him or any other researcher. In light of the absence of any data to support Dr. Robbins' conclusions, we are troubled by his outrageous allegation that manufacturers of athletic footwear are "irresponsible" for representing their products as offering improved protection. In fact, he further emphasizes the absurdity of his a llegations by attacking existing "safety standards" for footwear, when in fact everyone who works in this area knows that there are, as yet, no such standards. The biomechanical interactions between the body and the shoes and surfaces ove r whic h we run is an important topic for study . It promises to lead us to new ideas about the causes of overuse injuries, and it may result in new strategies for their treatment and prevention. But such careless and nonscientific soap-box oratory will not bring us any of these positive benefits, and in fact may result in more harm and misunderstanding. As a result of his research, Dr. Robbins makes the outrageous and untenable recommendation of "barefoot activity-where practical and socially acceptable." As readers of this widely read journal, we simply can not let stand such a radical and potentially harmful conclusion in the advance of any data to support it. E. C. Frederick, Ph.D. President Exeter Research, Inc. Peter R. Cavanagh, Ph.D. Professor and Director Center for Locomotion Studies Pennsy lv ania State University Response: Dear Editor-in-Chief: T his response to Frederick and Cavanaan's le tter provides !l lone awaited opportunity to deal with c on· tltct of interact M it pertains to scientific; publications. which M!: concerned us for some time, We first will de!!] with specific points they raise. It should be made clear that to in validate our position that the modern running shoe is unsafe, two conditions must be met. First, data must be produced suggesting a lower injury frequency with modern shoes, lower impact during running with these footwear, or showing expensive shoes (advertised as offering increased OfOtection: e.g., increased cushioning; "pronation corrccnon") protect better than inexpensive ehocs. Frederick and C avanagh render no references suggc;:,tingthis be cause none exist. Second, they must provide conv incing arg uments that our citations and data suggesting that these footwear are hazardous, and our causality theory are in 146 Official Journal of the American College of Sports Medicine error. We provided 15 references indicating safety COncerns, and 16 that support our causality theory (6). Despi te their inflated rhetoric, they question only two (1,3) of these 31 citations. Evidently they found no fault with the remaining 29, because if further data were available to fortify thei r anemic arguments they surely would have used them. For example, they concede impact during running is at its highest when runners use the softest soled shoes (5), and impact is invariably 20-25% greater when gymnasts land on thick soft mats when compared with hard surfaces (4). We encourage readers to seek out these citations. As for the two references they question, they contend we mislead because the time interval between Caspersen et al.'s (1) and Marti et al.'s (3) collection of data was shorter than what might be assumed from the publication dates. No statement in our report specified this interval because Caspersen et al.'s report, which we (and they) refer to does not mention dates (6). Since Frederick and Cavanagh provide no reference offering this date, this claim can be dismissed. They argue that we do not report references that are contrary to our position-an audacious allegation COnsidering no example follows. We (and perhaps they) are aware of no published report that does not support our analysis. Frederick and Cavanagh's assessment of Marti's work is fiction (2, 3). Of the 5,026 respondents in his study, inexpensive shoes «US $40) were worn by 311 (6.2% -not 2.7%), and 260 (5.1%) wore expensive ones (>US $95). Their respective frequency of injuries per year corrected for training mileage was 14.3 and 31.9- 123% greater injury frequency with expensive shoes. Differences of this magnitude (P < 0.05) are not easily dismissed as the work of statistical gremlins as they unconvincingly attempt. Obviously, features present in expensive footwear are injurious. If this relation between footwear cost and injury frequency were extrapolated upward linearly, athletic footwear costing more than US ' $300 could come with a guarantee of at least one injury per year. This adds novel meaning to the notion of getting value for one' s money. We believe Marti's work, as well as the 14 other references, support our conclusion: "Based on the above data, notwithstanding unsupported claims by footwear manufacturers of improved protection with their products, it seems appropriate to consider expensive running shoes from major manufacturers (and perhaps less expensive shoes) as unsafe." In re lation to footwear safety standards, Frederick and Cavunagh contend, "everyone who works in this area knows there are, as yet, no such standards." This is nonsense. Our group has voting representation on the following committees: American Society for Testing of Materials (ASTM) Group F08 Sport Equipment and Facilities; ASTM F08. 54 Athletic Footwear; ASTM F- 13 Safety and Traction in Footwear; American National MEDICINE AND SCIENCE IN SPORTS AND EXERCISE Standards Institute (ANSI) Z41 Performance Requirements for Protective Occupational Footwear. Each has advanced footwear safety standards, but, as stated in our text, "they are inadequate because they do not account for the discomfort-impact illusion." We have always thought that injury incidence can be reduced through footwear modifications (6-11) and have worked toward this goal through the above organizations. Their lack of knowle dge of these groups, let alone not being participating members, indicates that their passion concerning athletic footwear user safety is less than consuming. They argue that plantar perception during locomotion bears no relation to plantar sensibility at rest, yet provide no data or reference to support this. It is preferable in physiological research to simulate as c1os~ ly as possible natural conditions, which we mentioned in our text as a limitation. However, this shortcomi ng is shared by all experimental research, which is usu~l ly performed in a laboratory, and controls variables not controlled in nature. Surely they do not belier ve all experimental research-including their own-is invalid. Furthermore, we do not believe it is feasible to accurately measure perception of plantar load during actual running. Without providing a method, their comment is no more than empty rhetoric. They misquote us. It should read (6): "Barefoot activity when practical (no need for thermal insulation; no risk of crush injuries; social acceptability) deserves consideration since plantar sensory mediated protective adaptations seem optimized for this condition. Although this may run counter to notions prevalent in economically advanced countries recounting the dangers of barefoot activity and necess ity of footwear even when barefoot activity is feasible, supporting data are lacking, and many have c oncluded that footwear design is guided by fashion rather than health considerations." We stand behind the above statement, and Frederick and Cavanagh provide no reference or data suggesting that barefoot activity, when practical, is either "outrageous or untenable." We will now briefly deal with conflict of interest guidelines. MSSE is among a small group of medical journals that have no published guide lines that require authors (also editorial staff and rev iewers) to disclose potential conflicts of interest related to work s ubmitted for publication. Here are extracts of published guidelines from two medical journals: "The Journal asks authors of research articles to disclose at the time of submission any financial arrange, mem they may have with a c ompany w hose products figure nrnmlncntlv in the submitted manuscript, or with a comnanv making competing products ... Because the es senc e of revie ws and editorials is selection and interpretation of the literature, the Journal expects that authors of such articles will not have any financial interest in a company (or its competitor) that LETTERS TO THE EDITOR-IN-CHIEF J makes a product discussed in the ar ticle." (Information For Authors, The New England Journal fMedicine). " ... The letter should inc lude any inti, rmation not given on the title page that might be elevant to a possible conflict of interest, e.g., consultancies, stock ownership or patent licensing arranzements." (Infor mation For Authors, The Journal of the American Geriatrics Society). Individuals with financial interest in products that they investigate have difficulty in maintaining the detachment required to objectively interpret data. This conscious or unconscious bias results in commercial advertising-not science. Scientific publications have these guidelines to help assure reliable reporting and interpretation of research. Being late at developing conflict of interest guidelines has advantages. MSSE can introduce up-to-date guidelines- we believe that these standards in many journals could use modernizing. For example, despite disclosed financial interest in a product, authors are occasionally allowed to publish, with perhaps certain revisions to distance themselves from these products. We see nothing improper with this, other than that the reader is not informed about it. We believe that disclosed potential conflicts of interest should be included in published reports. The Editor-in-Chief is then freed to publish work without later risking charges regarding authors w ith conflicts of interest. Potential conflicts of interest could be reported following acknowledgments. In the case in point, Dr. Frederick was the previous director of research for a footwear manufacturer using the brand Nike. He has commercial relations (consulting and research contracts) with a number of athl etic footwear manufacturers through Exeter Research Inc., a personal corporation. Dr. Cavanagh has similar commercial relations with athletic footwear manufacturers using brands: Nike, Puma, Etonic, and Avia. It should REFERENCES 1. CASPERSON, C. J., K. E. POWELL, J. P. KOPLAN, R. W. SHIRLEY, C. C. CAMPBEll, and R. K. SIKES. The incidence of injuries and hazards in recreational and fitness runners (Abstract). Med. Sci. Soares Exerc. 16: 113, 1984. 2. MARTI, B. Relationships between running injuries and running shoes: results or a study or 5.000 participants in a Iti-km runthe May 1994 Berne Grand-Prix etudy. In; The Shoe in Spurt. W. rtornnzer and B. Se[!esser (Eds.). Chicago: Yearbook Medical Publiehere, 1989, pp. 256-265. 3. MARTI, B.• J. P. VADER, C. E. MINDER, and T. MELIN. On the epidemiology of running injurie~; the Bern Grand-Prix study. Am. 1. Sports Med. 16:285-294,1988. 4. McNITT-GMY, J. L. and T. YOKOI. The influence of surface characteristics on the impulse characteristics of drop landinos. rroceennas ortne mn Annual Meeting or tne America n S ociety on Iliomeehanics, Auo' 23-25, 1999, BuriinEton, VT, 1989, pp. 91-93. ). NIGG, B. M., A. H. BHILSON, J. DIiNOTll, S. M. LUlITm, and A. STACOFF. Factors influencing kinetic and kinematic variables in Official Journal of the American College of Sports Medicine 147 be noted that these footw ear manufacture rs produce products, presumably in part based on these consultants' recommendations, that our res earch has shown c re ates t he discomfort-impact illusion, thus promoting chronic overloading. These conflicts of interest, which were not disclos ed in their letter, change its meaning. For example, the ir defe nse of footw ear manufactur ers can be v iewed as a pretext to protect their financial position as consultants to them. What makes this example of conflict of int erest sad and cogent, is that these authors are senior researchers w ho act as role models for y ounger inv es tigators. Clearly, Frederick and Cav anagh are not happy that science is progressing along a path that they did not anticipate. Their letter is little more t han an advertisement for the current running shoe, in which they have financial interest, and for w hich they are in part answerable. As science, it is without substance, because after removing the camouflage of feig ned self- righteous indignation, hyperbole, platitudes, and jargon from their letter, there is not one refer ence (or ev en unpublished data or personal communication) suggesting that these footwear are safe, nor do they counter data we present indicating they ar e dangerous. Frederick and Cavanagh blame their displeasure on devious misleading authors, incompetent reviewers, blind editors, and decepti ve statistics. A more plausible and ethical explanation of their discontent is their lack of objectivity, and their self-interest. Steven E. Robbins, M.D. Gerard J. Gouw, Ph.D. (eng) Human Performance Group Department of Mechanic al Engineering Concordia University running. In: Biomechanics of Running Shoes. B. M. Nigg (Ed.). Champaign, IL: Human Kinetics Publishers, 1986, pp, 139-1 S9. 6. ROBBINS, S. E. and G. J. Gouw. Athletic footwear and chronic overloading: a brief review. Sports Med. 9:76-115, 1990. 7. ROHIHN~S, .E. and G. J. Gouw. Modern athletic footwear: unsafe due to perceptual illusions. Mad. Sci. Sports Exo»: 2J:217-224, 1991. SI. Ronnnrs, S. h. and A. M. YAI'JI'JA. Running related injury prevention through barefoot auaptauons, Mea. sa. soons sxeic. 19:148-156,1987. 9. RQHIHN~,S. E., A. M. HANNA, and O. J. oovw. ov enoac protection: avoidance of'hoavy plantar surface loading. Mad. Sci. Stxms tixerc. 20:1\)-92. 19M. 10. ROBBINS,S. E., A. M. HANNA,and G. J. Gouw. Running related injury prevention through innate moderating hshnvior. M uti Sci. Spons Exctc, 21;130-139. 1959. II. ROIlIlII'JS, S. b., A. M. lIANNA, and L. JONES. Sensory attcnuauon induced by modem athletic footwear. J. Test Eval; 16;412-416. 1988. |
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