First, adjust the desk or workbench to an appropriate height based on the nature of the work. Different desk heights require different seating positions, sometimes even necessitating a different chair. Once the desk height is fixed, you can adjust the chair height using various body parts as reference points.
Elbows: While maintaining a comfortable seated position, position elbows as close to the desk as possible to keep upper arms parallel to the spine. Place hands on the work surface (e.g., laptop or keyboard) and adjust seat height to ensure elbows form a 90-degree angle. Simultaneously, adjust armrest height so upper arms are slightly raised at shoulder level.
Thighs: Check if your fingers can slide freely under your thighs at the front edge of the seat. If space is too tight, add an adjustable footrest to support your thighs. If there's a finger's width between your thighs and the seat's front edge, raise the chair height.
Calves: With your hips pressed against the chair back, test whether a clenched fist fits between the back of your calf and the front edge of the seat. If this isn't easily achievable, the chair is too deep. Adjust the backrest forward, use a cushion, or switch chairs.
Lower Back: Avoid slouching in your chair when fatigued, as this places additional strain on your lower back and spinal discs. Keep your hips pressed against the chair back, ideally with a cushion to allow for a slight natural curve in your spine. This prevents slouching during fatigue and minimizes back strain.
Eye Level: Close your eyes, then slowly open them. Your gaze should naturally fall on the center of the computer monitor. If the monitor is positioned too high or too low, adjust it accordingly to reduce strain on your neck muscles.
Of course, prolonged static sitting is detrimental to health. Remember to stand and move for at least one to two minutes every half hour. Simple activities like stretching or using the restroom suffice. If possible, take a 20-minute walk. This not only relieves spinal pressure but also promotes blood circulation, delivering nutrients to all parts of the spine.