An interventional study of Foot-type-matched prefabricated insole and Neutral prefabricated insole in Musculoskeletal Discomfort and Foot Discomfort, sponsored by Universidad San Jorge. Completed at 1 site in Spain. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Universidad San Jorge · Not applicable, Interventional, and Treatment
The goal of this clinical trial was to learn whether prefabricated insoles chosen according to a worker's foot type reduce foot discomfort more than neutral prefabricated insoles in assembly-line workers who stand for most of their shift. The trial was carried out under real working conditions at an appliance manufacturing plant in Zaragoza, Spain (BSH Electrodomésticos España, Montañana plant).
The main question it aimed to answer was:
- Does foot discomfort change differently in workers who wear an insole matched to their foot type than in workers who wear a neutral insole?
Researchers compared a foot-type-matched insole (pronator or supinator model) with a neutral insole of the same manufacturer and material, both worn in the same model of safety shoe.
Participants:
The study was approved by the Research Ethics Committee of Aragón (CEICA, reference PI24/176). This record was registered retrospectively, after data collection had been completed.
BACKGROUND Prolonged standing at work has been associated with discomfort in the feet and lower limbs. Prefabricated insoles are often supplied to industrial workers, but it is uncertain whether selecting the insole model according to foot type adds benefit compared with a neutral insole worn in the same footwear.
PROJECT STRUCTURE This trial was the second phase of a two-phase project conducted at the BSH Electrodomésticos España plant in Montañana (Zaragoza, Spain). In phase 1 (cross-sectional assessment, May to November 2024), foot posture (Foot Posture Index, FPI-6), three-dimensional foot morphology (DOMESCAN 3D scanner), plantar pressures and anthropometric variables were recorded. During the phase-1 assessment, workers signed a written informed consent form for the intervention phase.
FOOT-TYPE CLASSIFICATION Workers were grouped into three foot types (pronated, neutral and supinated) by k-means clustering (k = 3) of the standardized FPI-6 total score and a truncated arch height index (instep height divided by truncated foot length, heel to first metatarsal head) obtained from the 3D scan, using the whole phase-1 sample. The cluster labels used in this trial were those recorded in December 2024, before allocation. The approved protocol did not specify the classification algorithm. Cluster membership is not equivalent to the clinical FPI-6 categories: some workers in the pronated or supinated clusters had FPI-6 total scores in the neutral range. Workers in the neutral cluster were not eligible.
RANDOMIZATION AND ALLOCATION Eligible workers were randomized 1:1 to the foot-type-matched or the neutral insole before insole delivery, using blocks stratified by foot-type cluster, sex and body mass index. The allocation list was recorded in March 2025. The company occupational health service delivered the insoles according to the allocation list. Participants were not told which insole type they had received; the staff who delivered the insoles were aware of the allocation. Analyst blinding was not documented, and the success of blinding was not assessed.
INTERVENTION Both groups wore the same safety shoe model (Galena, Paredes Seguridad, Spain). The experimental group received a prefabricated TSTEP insole (Paredes Seguridad, Spain) matched to the foot-type cluster: the pronator model for workers in the pronated cluster and the supinator model for workers in the supinated cluster. The control group received the neutral TSTEP insole, of the same material and characteristics as the foot-type-specific models. Insole delivery dates, wearing time, adherence and tolerability were not recorded in the analysis dataset.
OUTCOME ASSESSMENT Musculoskeletal discomfort during the previous working week was self-reported with a Spanish-language version of the Cornell Musculoskeletal Discomfort Questionnaire (CMDQ), completed online through a link sent by e-mail by the company occupational health service. According to the protocol, the baseline questionnaire was to be completed at insole delivery and the follow-up questionnaire three months later. The outcome questionnaires were completed between 22 October 2025 and 3 February 2026; in participants who completed two questionnaires, the median interval between them was 57 days (range 44 to 103 days). Because insole delivery dates were not recorded, the timing of the questionnaires relative to insole delivery cannot be verified for each participant, and a three-month wearing period cannot be assumed.
CHANGES FROM THE APPROVED PROTOCOL The approved protocol (version 3, 20 November 2024) specified: (1) CMDQ musculoskeletal discomfort as the primary variable, without defining a body region; (2) within-participant comparisons before and after insole delivery (paired t test or Wilcoxon signed-rank test); (3) stratified block randomization by foot type, sex, age and body weight, generated with randomizer.org by an independent investigator not involved in recruitment; (4) follow-up three months after insole delivery; and (5) a sample size of 6 participants per group (GRANMO), based on the CMDQ discomfort index.
As conducted and reported: (1) randomization was stratified by foot-type cluster, sex and body mass index; the use of randomizer.org and the independence of the person who generated the allocation sequence are not documented; (2) no statistical analysis plan other than the approved protocol is documented before data collection; in the trial report, written after data collection, the primary outcome was the bilateral foot CMDQ score (sum of the right-foot and left-foot regional scores), which was not prespecified in the approved protocol, and the primary analysis was a between-group analysis of covariance adjusted for baseline score, sex, body mass index and foot-type cluster in participants with two questionnaires, with a sensitivity analysis including all participants with at least one questionnaire; within-participant comparisons were reported descriptively; (3) the observed interval between questionnaires was shorter than the planned three months (see above); (4) the number of participants randomized was determined by the eligible workers available, not by the protocol sample size calculation; and (5) analyses were performed in Python 3 rather than IBM SPSS.
REGISTRATION This trial was not registered before enrolment. This record was created retrospectively, after completion of data collection, to make the trial and its deviations from the approved protocol publicly available.
STUDY START DATE The study start date in this record (22 October 2025) is the date of the first trial questionnaire, which also recorded electronic agreement to participate in the trial. Written informed consent for the intervention phase had been signed during the phase-1 assessment (2024), and the allocation list was recorded in March 2025.
FUNDING The safety shoes and insoles were purchased by BSH Electrodomésticos España S.A. Publication costs are funded by the Cátedra Empresa Sana.
NOTES ON THE APPROVED PROTOCOL An English translation of the approved protocol (version 3) is provided in the study documents. Its first page lists the investigators' clarifications of clerical errors in the approved text: the funding years (2014-2015 should read 2024-2025), the meaning of the Annex I declaration, the summary statistic for non-normal variables (median rather than mean) and the source of the standard deviation used in the sample size calculation. The protocol assigned pseudonymization and data analysis to different team members; in the trial, both were performed by the same investigator (A. J. Almenar-Arasanz).
ETHICS The protocol was approved by the Research Ethics Committee of Aragón (CEICA, reference PI24/176; favourable opinion 17 April 2024; amendment approved 4 December 2024, protocol version 3). The doctoral thesis project also received a favourable report from the Ethics Committee of Universidad San Jorge (report 53/2/23-24, 18 March 2024).
Universidad San Jorge is the lead sponsor of 33 studies on the registry; 4 are open to participants now.
Counted across the registry records on this site, refreshed daily.
The criteria were revised on the registry on Nov 10, 2026. See what changed
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Workers in the pronated or supinated foot-type cluster who were randomized to receive a prefabricated TSTEP insole matched to their cluster (pronator model for the pronated cluster, supinator model for the supinated cluster), worn in the work safety shoe (Galena model, Paredes Seguridad).
Other: Foot-type-matched prefabricated insole
Workers in the pronated or supinated foot-type cluster who were randomized to receive the neutral prefabricated TSTEP insole (same manufacturer and material as the foot-type-specific models), worn in the same work safety shoe model (Galena, Paredes Seguridad).
Other: Neutral prefabricated insole
Prefabricated TSTEP insole (Paredes Seguridad, Spain) selected according to the participant's foot-type cluster: the pronator model for workers in the pronated cluster and the supinator model for workers in the supinated cluster. The insole was worn inside the participant's work safety shoe (Galena model, Paredes Seguridad); the approved protocol planned three months of use. Insoles were delivered by the company occupational health service according to the allocation list. Insole delivery dates, wearing time and adherence were not recorded.
Also known as: TSTEP insole, pronator or supinator model (Paredes Seguridad)
Neutral prefabricated TSTEP insole (Paredes Seguridad, Spain), of the same material and characteristics as the foot-type-specific models; the approved protocol describes it as similar to the insoles workers had used before the study. The insole was worn inside the same work safety shoe model as in the experimental arm (Galena, Paredes Seguridad); the approved protocol planned three months of use. Insoles were delivered by the company occupational health service according to the allocation list. Insole delivery dates, wearing time and adherence were not recorded.
Also known as: TSTEP insole, neutral model (Paredes Seguridad)
Bilateral Foot Discomfort Score (Cornell Musculoskeletal Discomfort Questionnaire)
Sum of the right-foot and left-foot regional scores of the CMDQ (range 0 to 180). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. Compared between groups as the follow-up score adjusted for the baseline score. The approved protocol specified CMDQ musculoskeletal discomfort as the primary variable without defining a body region; the bilateral foot definition was established in the trial report after data collection.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
Complete CMDQ Total Score
Sum of the regional scores of all 20 CMDQ body regions (range 0 to 1800). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. The approved protocol specified CMDQ musculoskeletal discomfort without defining a body region or score; this complete total is the closest operationalization. In the trial report it was analyzed as an exploratory secondary outcome without adjustment for multiplicity.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
Right-Foot CMDQ Score
Right-foot regional score of the CMDQ (range 0 to 90). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. Defined in the trial report after data collection; analyzed as an exploratory secondary outcome without adjustment for multiplicity.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
Left-Foot CMDQ Score
Left-foot regional score of the CMDQ (range 0 to 90). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. Defined in the trial report after data collection; analyzed as an exploratory secondary outcome without adjustment for multiplicity.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
Lower-Limb CMDQ Score
Sum of the hip/buttocks, thigh, knee, lower leg and foot regional scores of the CMDQ (9 regions; range 0 to 810). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. Defined in the trial report after data collection; analyzed as an exploratory secondary outcome without adjustment for multiplicity.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
Axial/Spine CMDQ Score
Sum of the neck, upper back and lower back regional scores of the CMDQ (3 regions; range 0 to 270). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. Defined in the trial report after data collection; analyzed as an exploratory secondary outcome without adjustment for multiplicity.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
CMDQ Score Excluding Upper-Limb Regions
Sum of the neck, upper back, lower back, hip/buttocks, thigh, knee, lower leg and foot regional scores of the CMDQ (12 regions; range 0 to 1080). Each CMDQ regional score is the product of frequency (0, 1.5, 3.5, 5 or 10), severity (1 to 3) and interference with work (1 to 3), range 0 to 90 per region; higher scores indicate more discomfort. CMDQ: Cornell Musculoskeletal Discomfort Questionnaire, Spanish version, previous working week. Defined in the trial report after data collection; analyzed as an exploratory secondary outcome without adjustment for multiplicity.
Time frame: Baseline (planned at insole delivery) and follow-up (planned 3 months after insole delivery; observed median interval between questionnaires 57 days, range 44 to 103 days)
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No — Individual participant data will not be shared. The approved protocol states that study data will not be transferred to third parties and will be kept at most until February 2029 or until the defense of the doctoral thesis. The dataset contains health-related information on employees of a single workplace.
Ran from Oct 2025 to primary completion in Feb 2026, 3 months.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Universidad San Jorge