ExRx: Stress, environment and many exercises can contribute to a hunched-over effect.

Excessive thoracic kyphosis is a disproportionate forward rounding or curvature of the middle and upper back, also known as the thoracic spine (Kendall, McCreary & Provance 2005). ETK is an extremely common musculoskeletal imbalance brought on by prolonged time in some postural positions; exercise and/or activity choices; environmental factors; myofascial dysfunction; intolerances to food and/or other allergic reactions; and psychological stress. Read more here.