Can the Belgian Coastal Environment Improve Physical and Cognitive Health in Older Adults?

During the entire protocol, both in the first and second phases of the study, interbeat intervals (IBIs) will be recorded using the Polar H10 chestband. From these IBIs, heart rate variability (HRV) measures will be calculated. Time-domain measures will be expressed in milliseconds (ms), including SDNN (Standard Deviation of NN intervals) and RMSSD (Root Mean Square of Successive Differences). These parameters provide insight into autonomic nervous system activity, particularly parasympathetic modulation.

During the entire protocol, both in the first and second phases of the study, interbeat intervals (IBIs) will be recorded using the Polar H10 chestband. From these IBIs, heart rate variability (HRV) measures will be calculated. Frequency-domain measures, including low-frequency (LF) power, high-frequency (HF) power (expressed in milliseconds squared [ms²] or normalized units [nu]), and the LF/HF ratio (unitless), will be analyzed. These parameters provide insight into autonomic nervous system activity, with HF power primarily reflecting parasympathetic modulation and the LF/HF ratio indicating the balance between sympathetic and parasympathetic influences.

Electrodermal activity (EDA) of participants will be measured using the EmbracePlus wristband. EDA will be continuously recorded throughout the entire protocol, both during the first and second phases of the study. The primary EDA outcome measures include skin conductance level (SCL) and skin conductance responses (SCRs), both expressed in microsiemens (µS), These parameters provide insight into sympathetic nervous system activity and arousal dynamics.

Saliva samples will be collected in the first phase of the study, at 4 time points: before the exposure (baseline), after the seated exposure of 15 minutes, right after the walk, and 20 minutes after the walk. These saliva samples will be analysed for the presence of cortisol, which is expressed in nmol/L.

Sustained attention will be measured immediately before and after exposure to both environments, in both phases of the study. The validated d2 test of attention will be used for this. One outcome of this test is the total number of items processed (TN). This represents the total number of stimuli (letters) that a participant has scanned and attempted to process within the given time, with higher numbers indicating better sustained attention.

Sustained attention will be measured immediately before and after exposure to both environments, in both phases of the study. The validated d2 test of attention will be used for this. Another outcome of this test is the performance (P). This is calculated as the number of correctly marked target stimuli minus the number of errors (including both commission and omission errors). The higher this performance score, the better the participants' sustained attention.

Sustained attention will be measured immediately before and after exposure to both environments, in both phases of the study. The validated d2 test of attention will be used for this. Another outcome of this test is error percentage. This indicates the percentage of errors relative to the total number of marked items. Errors can be divided into: 1) commission errors (false positives) and 2) ommission errors (false negatives). Commision errors represent the incorrectly marked symbols that are not target stimuli. The ommission errors are the target stimuli that weren't marked. The lower the error percentage, the better participants' sustained attention.

Processing speed will be measured immediately before and after exposure to both environments, in both phases of the study. The validated Symbol Digit Modalities Test will be used for this. One outcome measure is the number of total correct responses. This is the number of correct symbol-digit pairings made within the given time limit. The higher this number, the better participants' processing speed.

Processing speed will be measured immediately before and after exposure to both environments, in both phases of the study. The validated Symbol Digit Modalities Test will be used for this. Another outcome measure of this test is the error rate, which is the number of incorrect responses. The lower the error rate, the better for participants' processing speed.

Perceived stress will be evaluated immediately before and after exposure to both environments. This will be measured using one question asking the participant "How stressed are you now?", which has to be scored on a ten-point Likert scale ranging from 1 (labelled "Not at all stressed") to 10 (labelled "Totally stressed").

Perceived mental exhaustion will be evaluated immediately before and after exposure to both environments. This will be measured using one question asking the participant "How mentally exhausted are you now?", which has to be scored on a ten-point Likert scale ranging from 1 (labelled "Not mentally exhausted at all") to 10 (labelled "Totally mentally exhausted").

Positive mood will be evaluated immediately before and after exposure to both environments. This will be measured using the "Positive and Negative Affect Schedule". Participants will have to indicate to what extent they experience each of the emotions or feelings listed on a scale ranging from 1 (labelled "Very slightly or not at all") to 5 (labelled "Extremely").

In the first phase of the study, participants will keep a sleeping diary for 14 days, to see whether the exposures to the different environments have an effect on their sleep quality.