Many people over 70 in Spain can walk comfortably on flat ground but struggle to climb the stairs in their own homes. Felipe Isidro, Professor of Physical Exercise and Health, has drawn attention to the problem; his analysis, widely shared on social media, highlights a gap in how we understand aging and mobility.
Isidro says the issue stems in part from the early loss of fast-twitch muscle fibers. These fibers generate quick, powerful bursts of force, the kind needed to lift the body up each step. Walking on level surfaces relies on slow-twitch fibers and steady, continuous effort, while stairs demand a sudden, concentrated push from one leg, often with the knee bent at a sharp angle.
Different Demands
Walking on flat ground is a rhythmic, horizontal movement that many older adults can maintain for long periods. It requires balance and endurance but does not test the body's ability to generate the same force needed for an explosive movement. So, many seniors remain active walkers yet struggle with tasks that require more strength, such as climbing stairs or rising from a low chair.
Stair climbing, by contrast, is a vertical challenge. Each step forces the body to lift its full weight, often placing three to four times the person's body weight on a single leg. The movement is brief but intense, making any loss of muscle mass or joint flexibility quickly apparent. For some, this means pain, breathlessness or a need to pause after just a few steps.
That contrast is why clinicians assess more than walking when investigating possible sarcopenia. Specialists consider several tasks, including lifting or carrying and walking, as well as climbing stairs or rising from a chair, as Berbel explained in comments reported by La Vanguardia. Stair climbing can reveal limitations that level walking may not, but difficulty on stairs is not by itself a diagnosis. Pain can affect performance, as can balance problems. Joint disease and cardiovascular limitations can also play a part.
Muscle Loss and Aging
Isidro identifies sarcopenia, the age-related decline in muscle strength and muscle quantity or quality, as a basic factor. The European Working Group on Sarcopenia in Older People places low muscle strength at the center of its consensus approach. Reduced muscle quantity or quality helps confirm the condition, while impaired physical performance indicates greater severity. Fast-twitch fibers, which are responsible for rapid, forceful movements, tend to decline earlier and more sharply than slow-twitch fibers. Older adults may so retain the ability to walk but lose the strength needed for more demanding actions. Bone density loss and increased arterial stiffness can further limit mobility.
The issue is impressive in Spain, although stair difficulty can have multiple causes. A study involving 686 people aged 60 and older reportedly found sarcopenia in about one in eight participants. Separately, estimates from OsteoSER, a project of the Sociedad Española de Reumatología, put osteopenia at 54.4% among people over 50 and osteoporosis at 10.7%, figures reported by Diario de Navarra in its coverage of Clínica Universidad de Navarra experts and the project. These population figures do not mean that every person who struggles with stairs has sarcopenia. Muscle loss and bone health may overlap with pain or balance issues, as well as other health conditions.
This mismatch explains why walking is not a complete measure of functional strength. Someone who appears fit while strolling may still face impressive barriers at home, especially in buildings with multiple flights of stairs or where daily routines require frequent climbing.
What Can Help
To address the problem, Isidro recommends targeted muscle strengthening and improved stair-climbing technique. He also advises adapting the home environment. Strength training can help build and preserve muscle, while safer movement patterns reduce strain on joints. Home modifications, such as installing handrails or reducing the number of steps, can make a impressive difference for people with limited strength.
Isidro notes that simply walking more is not enough. Stair climbing has specific demands that require focused exercises and, in some cases, changes to the living space. Not everyone over 70 will experience these difficulties, but being able to walk does not guarantee the strength needed for all daily activities. The World Health Organization’s guidance for older adults pairs aerobic activity with muscle-strengthening activity at least twice a week. It also recommends balance-focused activity at least three times a week; the appropriate activities and level of effort should suit the individual.
Persistent or worsening difficulty climbing stairs is worth discussing with a health professional rather than automatically attributing it to normal aging. An assessment can consider strength and function, along with symptoms such as breathlessness or pain, and any unsteadiness.
Context and Practical Advice
Spain's aging population and prevalence of multi-story homes make this issue especially relevant. Recent data show that more than 20% of Spaniards are now over 65, and many live in buildings without elevators. National guidance increasingly emphasizes strength training for older adults alongside aerobic activity. For families and caregivers, recognizing the difference between walking ability and functional strength is basic to supporting independence at home.
