This observational crossover study aims to evaluate how different bag carrying styles-backpack, shoulder bag, and handbag-may affect gait parameters in healthy adults. Fifteen participants will walk under four conditions (no bag and each of the three bag types with a load of 15% of body weight), with the order randomized. Gait will be assessed using a 3D motion capture system with integrated force plates. Posture and lower extremity muscle strength will also be evaluated for baseline characterization.

This observational crossover study was conducted at a university-based Gait Analysis Center between October 2023 and October 2024, following ethical approval from the University Medical Research Ethics Committee (approval number: 2022-19/07, dated 09.12.2022). The study aimed to evaluate how different bag carrying styles-specifically, carrying a backpack, a shoulder bag, and a handbag-may influence gait parameters in healthy adults.

Fifteen volunteers aged 18 to 30 years who met predefined inclusion criteria were enrolled. Baseline posture was evaluated using the New York Posture Analysis (NYPA), and lower extremity muscle strength was assessed with a handheld myometer to ensure a consistent starting profile across participants. These values were recorded for characterization purposes only and were not analyzed in association with gait outcomes.

Each participant completed walking trials under four different conditions: walking without a bag, with a backpack, with a shoulder bag, and with a handbag. The order of these conditions was randomized for each participant. For each loaded condition, bags were adjusted to carry 15% of the individual's body weight. Participants walked barefoot at a self-selected pace on a 10-meter walkway while gait data were collected using a 3D motion analysis system (Vicon) integrated with force plates. Reflective markers were placed on anatomical reference points on the lower extremities.

Spatial-temporal, kinematic, and kinetic gait parameters were recorded in each condition, including stride length, cadence, joint angles, and joint power. Rest periods of at least three minutes were provided between walking conditions to reduce fatigue. All measurements were performed during a single session.

This study used a prospective crossover design in which each participant was observed under all four conditions. No therapeutic or clinical interventions were applied. The goal was to observe within-subject variability in gait characteristics associated with temporary exposure to different bag-carrying styles under standardized laboratory conditions.

Inclusion Criteria:

• 18-30 years of age,
• score above 45 on the New York Posture Analysis (NYPA)
• lower extremity muscle strength values measured with myometer greater than 24,
• No strenuous physical activity 48 hours before
• Being cooperative with the measurements and tests, and volunteering to participate in the study

Exclusion Criteria:

• Having a diagnosed orthopedic or neurological problem,
• Having visual problems,
• Having a body mass index of 30 kg/m² or more,
• Having pain complaints due to a history of trauma in the last 1 month,
• Having a leg length difference of more than 0.5 cm

The study population consisted of 15 healthy volunteers who were selected using a simple random sampling method from among those who volunteered at Acıbadem Altunizade Hospital.

Individual participant data will not be made available to other researchers