インソールには障害を回避するだけの効果はなく、フィット感やフィーリングの問題のようだ。だから、靴付属のインソールでも良いし、安いインソールをいろいろ試してもよい。好みの問題と言える。

RCT(ランダム化比較試験)のデザインによるしっかりとした研究。参加者総数は1205名。ソルボ(3ミリ厚)とPoron(発泡ポリエチレン3ミリ厚)とSaran(繊維でできた3ミリ厚)の比較。踵の衝撃をソルボやPoronは吸収するが、障害率はまったくSaranと変わらなかった。

J R Soc Med. 2006 Jan;99(1):32-7.

Do shock absorbing insoles in recruits undertaking high levels of physical activity reduce lower limb injury? A randomized controlled trial.

Withnall R, Eastaugh J, Freemantle N.

Department of Epidemiology, Walter Reed Army Institute of Research, Washington, DC 20307-5100.

Abstract

A prospective controlled trial was carried out to determine the usefulness of a viscoelastic polymer insole in prevention of stress fractures and stress reactions of the lower extremities. The subjects were 3,025 US Marine recruits who were followed for 12 weeks of training at Parris Island, South Carolina. Polymer and standard mesh insoles were systematically distributed in boots that were issued to members of odd and even numbered platoons. The most important finding was that an elastic polymer insole with good shock absorbency properties did not prevent stress reactions of bone during a 12-week period of vigorous physical training. To control for the confounding effects of running in running shoes, which occurred for about one and one-half hours per week for the first five weeks, we also examined the association of age of shoes and cost of shoes with injury incidence. A slight trend of increasing stress injuries by increasing age of shoes was observed. However, this trend did not account for the similarity of rates in the two insole groups. In addition, we observed a strong trend of decreasing stress injury rate by history of increasing physical activity, as well as a higher stress injury rate in White compared to Black recruits. The results of the trial were not altered after controlling for these factors. This prospective study confirms previous clinical reports of the association of stress fractures with physical activity history. The clinical application of a shock absorbing insole as a preventive for lower extremity stress reactions is not supported in these uniformly trained recruits. The findings are relevant to civilian populations.

矯正用のインソールは脚の使いすぎから来る障害には効果がない。RCTデザインによるエビデンスの高い研究

Scand J Med Sci Sports. 2010 May 12. doi: 10.1111/j.1600-0838.2010.01116.x. [Epub ahead of print]

Can orthotic insoles prevent lower limb overuse injuries? A randomized-controlled trial of 228 subjects.

Mattila VM, Sillanpää PJ, Salo T, Laine HJ, Mäenpää H, Pihlajamäki H.

Centre of Military Medicine, Lahti, Finland Department of Orthopaedic Surgery, Hämeenlinna Central Hospital, Hämeenlinna, Finland Department of Orthopaedic Surgery and Trauma, Tampere University Hospital, Tampere, Finland Military Hospital of Santahamina Garrison, Finnish Defence Forces, Helsinki, Finland Department of Medical Services, Defence Staff, Finnish Defence Forces, Helsinki, Finland.

Abstract

Lower limb overuse injuries are common among people who are exposed to physical stress. Orthotic shoe insoles are widely used to prevent lower limb overuse injuries. Here, we conducted a randomized-controlled study to examine whether the use of orthotic insoles prevents lower limb overuse injuries. Participants (n=228) were randomly assigned to use (n=73) or not to use (n=147) orthotic insoles. The insoles were molded to the shape of the foot to provide support during physical activity. The main outcome measure in the present study was the physician-diagnosed lower limb overuse injury. Thirty-four (46.6%) subjects in the insole group were diagnosed with a lower limb overuse injury compared with 56 (38.1%) in the control group (P=0.29) during the 6-month study period. When body mass index and the results of a 12-min running test and muscle strength were adjusted in a Cox's regression model, the hazard ratio for lower limb overuse injury in the insole group was 1.3 (95% confidence intervals: 0.8-2.1) compared with the control group. Use of orthotic insoles was not associated with a decrease in lower limb overuse injuries. Our findings suggest that routine use of orthotic insoles does not prevent physical-stress-related lower limb injuries in healthy young male adults.