The aim of this study is to evaluate the effects of chairs with different ergonomic designs on quality of life, discomfort, and pain in individuals with coccydynia (tailbone pain).

Participants aged 18-65 years who work at a desk for at least 5-6 hours per day will be included in the study. Information such as age, height, body weight, education level, family type, smoking status, sex, marital status, working posture (sitting, standing, or both), duration of working hours, job type (production or administrative), regular exercise habits, presence of chronic diseases, and absence of any spinal problems (e.g., no diagnosed lumbar disc herniation) will be recorded. Participants will be randomly assigned to six groups. Before using the chairs, participants will be seated on a load cell-equipped chair to assess weight distribution. The distribution of body weight across different regions while sitting will be recorded in kilograms. This measurement will be repeated three times, and the average will be recorded.

After the measurement, participants will be provided with specially designed chairs and asked to work using these chairs. Six different chair designs will be developed for the study. The reason for having six types of chairs is that the foam properties used in each chair will differ from one another.

Inclusion Criteria:

• Aged between 18 and 65 years
• Working at a desk for at least 5-6 hours per day
• Experiencing coccydynia (tailbone pain)
• Able to sit independently without assistive support
• No diagnosed spinal disorders (e.g., lumbar disc herniation)
• Willing to use the assigned chair during working hours for 1 week
• Able to understand and complete questionnaires
• Provided written informed consent

Exclusion Criteria:

• History of spinal surgery
• Diagnosed spinal disorders (e.g., lumbar disc herniation, scoliosis, severe degenerative spine disease)
• Neurological disorders affecting posture, sitting balance, or sensation
• Severe musculoskeletal conditions (e.g., hip or pelvic disorders) that may affect sitting
• Pregnancy
• Inability to sit for prolonged periods
• Use of assistive seating devices (e.g., orthopedic cushions) during the study period
• Regular use of pain medication that may affect outcome measures

Individual participant data (IPD) will not be shared due to privacy and confidentiality considerations.