A prospective observational cohort study will be conducted between January 2022 and June 2022 in a Nursing public school in Portugal. Data collection will take place at the end of January and in the first days of February.

The study will enroll nursing students from a Portuguese Nursing School, and which are exposed to standing environments during acute clinical settings (e.g., hospitals). The recruitment process will be developed according to the following inclusion criteria: (i) nursing students enrolled, at the moment of the study, in a Nursing degree; (ii) nursing students that, at the moment of the recruitment phase, are not enrolled in a clinical learning setting; and the following exclusion criteria: (i) diagnosed chronic systematic diseases (e.g., rheumatoid arthritis); (ii) diagnosed metabolic disorders; (iii) visible lower limb swelling; (iv) presence of contraindications for baropodometric-related measurements; (v) history of orthopedic neurological and/or musculoskeletal problems likely to affect gait; and (vi) students that, at the moment of the recruitment phase, are also committed to a professional working activity or involved in high competition sports, which might influence foot health (e.g., waitress, door-to-door delivery, among others).

Participants will first be addressed in a project presentation session, where informed consent will be provided for their analysis and signature. Subsequently, the days for data collection will be scheduled, taking into consideration the most convenient periods for students and the research team. In this sense, a convenience sample will be recruited, as students will voluntary show up to participate in the study. This sampling method was chosen, rather than randomization, due to time constraints regarding project schedule, and also the need to achieve a representative sample. As we are performing the study only in one Nursing School, due to researchers' availability and ethical approvals, randomization could include students that wouldn't be able or didn't want to be part of the research in progress. In this sense, the research team opted to include volunteers, also helping decrease potential loss to follow-up.

In the Nursing School involved in this study, clinical training has an average duration of 4 to 5 months for students in the third and fourth year of the Nursing degree. Thus, the study will depend on this timeframe for the respective follow-up period.

According to the defined criteria, all undergraduate nursing students at the third year will be recruited as participants. Each academic year, an average of 300 students are enrolled, and for a confidence interval of 95% and a margin of error of 5%, the sample size needed is 169 participants. Also, an a priori 0.05 significance level is defined and a response distribution of 50% is assumed. To prevent potential losses, we've added an additional 15% of the total sample size, thus aiming to recruit 194 students.

All data collection will take place inside the Nursing School, in specifically chosen places, previously tested for the study, and will be performed by two researchers, which will be different from those responsible to analyze data.

The exposure under study consists of a particular environment that poses particular biomechanical risks to the foot/ankle region. According to Bernardes et al. (15), standing environments include those of prolonged standing and prolonged walking, which can be defined as spending at least 5% of occupational time standing or walking (21).

The first primary outcome of interest is related to the change in podiatric profile at 5 months and will be evaluated at month 0 and month 5, being an objective and quantitative outcome. In this case, specific foot-related variables while walking will be recorded, illustrating the actual behavior of the foot during activity. The assessment of the podiatric profile follows the important premise that the medial longitudinal arch is one of the most important and highly variable structural characteristic of the human foot (22).

The relevant variables that describe this outcome are summarized in Table 1.

This outcome includes foot posture and foot function assessments, which are relevant biomechanical measures, that can be extracted from the plantar pressure scans acquired previously.

Foot posture can be characterized using the modified arch index (MAI), which is calculated by the division of the foot length, minus the toes, in three equal portions, and also the division of pressure in the middle third by that of all three regions.

Foot function is characterized by the center of pressure excursion index (CPEI), which is a measure of foot function throughout the gait cycle, being defined as the distance between an imaginary line drawn from the first and last points of each foot's center of pressure (COP) trajectory and the COP as the distal third tertile of the foot. This value is usually normalized by foot width and multiplied by 100, to obtain a percentage excursion of the COP.

Following previous similar studies (7), CPEI and MAI's distribution are divided into quintiles. For the first, feet in the top and bottom quintile will be considered as having a supinated and pronated foot function, respectively, and for MAI, the top and bottom 20% will be considered pes planus and pes cavus, respectively.

Another variable of interest to characterize the podiatric profile is plantar loading characteristics. As there is no current consensus in the literature for the definition of adequate foot segments, this study will consider the templates of similar studies, which showed good reliability for plantar forces and pressures during barefoot walking in healthy adults (23). Namely, the regions to assess and compare are: lateral heel, medial heel, midfoot, 1st metatarsophalangeal joint (1MPJ), 2nd−5th metatarsophalangeal joint (2–5MPJ), hallux and the lesser toes.

The second primary outcome concerns the change in foot health at 5 months, a subjective evaluation by the participant, and is related to observed clinical parameters, signs and symptoms, namely skin, nails, foot structure, as well as presence and location of the pain. The Portuguese adaptation of the Self-Administered Foot Health Assessment Instrument (S-FHAI), a Likert-type instrument with four dimensions, will be used. It will be applied at month 0 and month 5. The majority of observed foot disorders will be recorded as either present or absent.

The study also includes the following secondary outcomes: (i) Foot Self-Care Knowledge, which is assessed between month 0 and month 5, through a four-dimensional questionnaire, where specific interventions for the promotion and prevention of foot and ankle disorders are evaluated; and (ii) Students' perceptions about the influence of foot health in their quality of life. It is evaluated through focus groups after exposure time (month 5).

Regarding potential effect modifiers and confounders, we expect that different nursing activities and ward typology (e.g., surgical units, intensive care) might produce diverse baropodometric patterns.

The primary and secondary outcomes, respective instruments for evaluation and timeframes for assessment are summarized in Table 2.

After recruitment, at month 0 (before exposure) and month 5 (after exposure), the participants will undergo a four-phased procedure:

To record the desired data, the Emed^® platform from novel.de will be used. It consists of a pedography platform to measure pressure distribution under the foot, containing calibrated capacitive sensors, with the potential to accurately measure foot pressure in static and dynamic positions.

The main variables measured (throughout time) are: maximum pressures, pressure/time, force exerted, contact area and COP line.

According to the provider, the sensor platform has an area (mm) of 475 × 320 with a total of 6,080 sensors, with a resolution (sensor/cm²) of 4. The recording frequency is set at 50 Hz, with a pressure range (kPa) of 10–1.270. The pressure threshold is 10 kPa and the maximum total force is 193,000 N.

The primary outcomes and the Foot Self-Care Knowledge (secondary outcome) will be analyzed using SPSS Statistics v25, namely with descriptive statistics (average; standard deviation; medians) with an a priori significance value of p < 0.05.

After verifying the type of distribution of the sample, using the Kolmogorov-Smirnov (KS) with Liliefors correction (suitable for samples with more than 30 subjects) (30), either the independent samples t-test (normal distribution) or the Mann-Whitney (test non-normal distribution) will be used to compare changes in outcomes before and after the exposure.

To relate variables of interest, namely podiatric profile variables and specific foot-health parameters, a Multiple Linear Regression will be computed and multivariate analysis of variance with repeated measures to detect significant interactions between variables.

To control confounding effects, we'll perform a stratification of variables, and evaluate the exposure-outcome association, also using Mantel-Haenszel (M-H) estimator for an adjusted result. Additionally, the Analysis of Covariance (ANCOVA) will be computed to assess the effect of certain factors on the outcome variables.

The secondary outcome, related to the students' perceptions, will be analyzed using ATLAS.ti v7 software, based on the content analysis as defined by Bardin (31). The different phases of analysis are: (i) pre-analysis; (ii) exploration of the material; and (iii) treatment of results, inference and interpretation. The categorical organization of the content will be performed a posteriori, through the following codification steps: (i) cutting—choice of units; (ii) enumeration—choice of counting rules; and (iii) classification and aggregation of chosen categories and units.

Potential missing data will be handled using marginal mean imputation, this is, computing the mean of the missing value, X, using the non-missing values and use it to impute missing values of X.

Regarding loss to follow-up, all data belonging to participants that choose to opt-out or are lost during the study, will be erased from storage, as explained in the informed consent document.