If Going Downstairs Feels Easy, What Are Your Legs Doing?

Going downstairs can seem like the easy half of using a staircase, especially beside the effort of climbing. But does calling the downward trip easy tell us enough about what the legs have to do?

Oxygen use and heart rate offer one way to describe the demand. In a small controlled comparison, five healthy men walked against the direction of moving escalators: upward on a descending escalator and downward on an ascending one. This kept them at the measurement point through five-minute trials. At each matched stepping rate, average oxygen use and heart rate were lower during descent. These were sustained, controlled bouts, not short trips down fixed stairs. The results fit the familiar feeling of easier breathing, although the study did not measure how breathless the men felt.¹

The legs still have an active task: braking the body as it lowers. In brief trials with 34 healthy, young, recreationally athletic adults, movement recordings and force measurements supplied estimates of the mechanical work around the hip, knee and ankle. Participants climbed and descended the same four-step staircase, keeping their stepping rhythm matched in both directions. During the supporting part of a downward step, substantial mechanical energy was absorbed around the knee and ankle. Climbing predominantly involved positive mechanical work, producing mechanical energy to raise the body. The work also changes within a step: descent includes both energy-absorbing and energy-generating phases.²

Mechanical work describes how mechanical energy is added or absorbed around the joints as the body moves. Oxygen use reflects a physiological cost of carrying out that movement, while heart rate provides another measure of the body's response to the task. An active braking task can therefore coexist with lower oxygen use and heart rate. These findings came from different people and protocols, so they do not establish what caused the lower oxygen-use response. What a movement asks of the body now is a different question from how the body might change after doing it repeatedly. These studies do not show whether ordinary stair use builds strength or whether descent is better exercise than ascent.^1,2

If you aren't out of breath after going downstairs, it is easy to wonder whether the trip counts for anything. There is more than one question in that thought: how it felt, what you did, and what you hope exercise will do for you. Separating those questions gives you a clearer way to think about the stairs without having to label the whole trip a workout.