The act of walking, or gait, is a complex, rhythmic motion that moves the body forward while maintaining balance. Biomechanical analysis of gait involves breaking down this motion into measurable parameters. One key metric is the Double Support Time (DST), which reflects the time both feet are simultaneously in contact with the ground during a single gait cycle. This measurement provides a window into an individual’s stability, balance control, and the maturity of their walking pattern. DST changes dramatically across the lifespan, serving as a functional marker for development, efficiency, and aging.
Understanding Gait and Double Support Measurement
The gait cycle is defined as the time from the heel strike of one foot to the subsequent heel strike of the same foot. This cycle is divided into two primary phases: the stance phase, when the foot is on the ground, and the swing phase, when the foot is in the air. In a healthy young adult, the stance phase typically occupies approximately 60% of the cycle, and the swing phase makes up the remaining 40%.
Double Support Time is the portion of the stance phase when both feet are bearing weight concurrently, occurring twice during every complete gait cycle. This period begins when the heel of the leading foot touches the ground and ends when the toe of the trailing foot pushes off. Measuring DST is a direct assessment of dynamic stability. A higher DST indicates a greater reliance on a broader base of support to maintain balance, while a lower DST is characteristic of a more efficient gait.
Double Support Time During Developmental Walking
The period of learning to walk is characterized by elevated Double Support Time as the body prioritizes stability. A newly walking toddler, typically between 12 and 18 months, may spend up to 40% of their gait cycle in double support. This high percentage is a compensatory strategy for an immature nervous system, limited leg strength, and an underdeveloped sense of balance. The initial walking pattern is often wide-based and characterized by a flat-footed landing without the heel-to-toe progression seen in adults.
As the child gains coordination and strength, gait maturation begins, marked by a rapid decrease in DST. By approximately two years of age, the child develops a heel-strike pattern and begins to exhibit reciprocal arm swing. This development allows the child to spend more time on one leg, increasing the single limb support time toward the mature pattern. By the time a child reaches about four years old, the parameters of their gait are largely established. Their DST continues to decline, approaching efficient adult values as the gait pattern fully matures around seven to ten years of age.
Stability and Efficiency in Adult Gait
The DST of a healthy young and middle-aged adult walking at a comfortable pace establishes the baseline for efficient human gait. For this population, DST typically ranges from 18% to 20% of the gait cycle. This low percentage reflects an optimal balance between speed, stability, and energy expenditure. Maximizing the single-limb support phase minimizes the overlap where both feet are on the ground, which allows for maximal forward propulsion and walking speed.
As individuals progress through healthy aging, a shift in the double support time begins to occur, generally starting around age 60 to 65. Even in the absence of disease, the DST begins to increase gradually, sometimes rising to 26% or more in healthy older adults. This increase is an adjustment driven by age-related changes, such as mild declines in balance control and slower reaction times. The body instinctively prolongs the time both feet are on the ground, widening its window of stability. This compensatory strategy effectively reduces the time spent in the single-limb support phase, thus lowering the risk of a fall.
Factors That Influence Double Support Beyond Age
While age drives a predictable progression of Double Support Time, several other factors can cause acute or pathological changes. Walking speed is one of the most influential variables, exhibiting a strong inverse relationship with DST. When a person walks faster, DST decreases, and conversely, walking slowly increases DST. This demonstrates the body’s ability to rapidly adjust its stability strategy based on immediate demands.
The environment and the body’s current state also play a major role in altering double support. When navigating uneven terrain or performing a simultaneous cognitive task, such as talking or solving a problem, the DST often increases. This “dual-tasking” effect reflects the nervous system diverting resources to balance. Pathological conditions, particularly those affecting the neurological or musculoskeletal systems, also lead to increased DST. For instance, an injury like a sprained ankle or a chronic condition like peripheral neuropathy results in a prolonged double support phase as the body maximizes stability to compensate for impaired sensation or weakness.