What is Double Support Time?
Double support time (DST) is a gait parameter that measures the percentage of a person's walking cycle during which both feet are simultaneously on the ground. This occurs briefly at the beginning and end of each stance phase. The duration of this period is directly related to walking speed; as a person's speed decreases, their DST tends to increase. For older adults, an increase in DST is a common and often beneficial adaptation to maintain stability and prevent falls. While a lower DST can indicate a more vigorous, dynamic gait typical of younger adults or athletes, a slightly higher DST in seniors is often a sign of a cautious but stable walking pattern.
The Relationship Between Aging and Gait
Gait naturally changes as we age. For many, these changes are a proactive strategy to maintain safety. Common age-related gait differences include a slower walking speed, shorter steps, and a wider base of support (step width).
- Increased Stability: The increase in double support time provides a more stable foundation, allowing older adults to spend more time controlling their center of mass as they move forward.
- Reduced Propulsive Force: Calf muscle strength tends to decrease with age, leading to a reduced push-off during the gait cycle. The body compensates for this by taking shorter steps, which also increases DST.
- Neurological Factors: Cognitive and neurological changes can also influence gait. Studies have shown that dual-task walking (walking while performing another task) can further increase DST, especially in older adults, as they use more attentional resources to maintain balance.
Is 30% Double Support Time a Good Result for Seniors?
A double support time of 30% for an older adult is generally considered a good and healthy score. For reference, typical walking behavior for the general adult population often falls between 28% and 40%. While younger, healthy adults may have a DST closer to 20%, the 30% range for a senior is not a cause for concern. Instead, it indicates a stable and confident walking pattern. It suggests that they have adopted a walking strategy that prioritizes balance and fall prevention without being overly cautious, which might push the percentage much higher (e.g., into the 40s).
If the individual is recovering from a surgery or injury, a DST of 30% could be a positive sign of recovery. A very high DST (above 40%) could indicate a significant struggle with balance or an increased fear of falling, whereas a value in the 20s for a senior might suggest a more robust or faster pace, but may also increase fall risk if not accompanied by excellent balance and strength.
Factors That Can Affect Double Support Time
Several variables can influence a person's DST, especially in older adults. It is important to consider the context of the measurement.
- Walking Speed: Slower walking speeds will naturally lead to a higher DST. If a senior's walking speed is slower than average, a DST of 30% is perfectly normal.
- Underlying Health Conditions: Conditions like arthritis, neurological disorders (e.g., Parkinson's), or peripheral neuropathy can affect gait and influence DST.
- Terrain: Walking on uneven or slippery surfaces will cause older adults to increase their DST for added stability.
- Fear of Falling: A fear of falling can cause a person to adopt a more cautious gait, leading to a higher DST. This can be a self-fulfilling prophecy, as the cautious gait can itself contribute to a decline in overall mobility.
How to Interpret Gait Analysis Results
Interpreting gait analysis requires a holistic perspective. While a single metric like a DST of 30% provides valuable insight, it is best understood in conjunction with other parameters.
- Context is Key: Always consider the individual's age, baseline fitness, and any existing medical conditions. A physical therapist can provide the most accurate interpretation.
- Look for Trends: A single measurement is less telling than a trend over time. For example, if a senior's DST gradually increases over several months without a corresponding reason (like an injury), it may warrant further investigation.
- Combine with Other Metrics: Analyze DST alongside other gait parameters, such as gait speed, step length, and cadence. A slowing gait speed coupled with an increase in DST is a classic sign of age-related gait change.
- Consider the Environment: The conditions under which the measurement was taken are important. Was the person walking on a flat, even surface, or were they navigating obstacles?
Strategies for Improving Gait and Balance
Maintaining good gait mechanics and balance is crucial for healthy aging. Here are some strategies and exercises that can help:
- Gait Training: A physical therapist can use gait training exercises to improve walking ability, balance, and strength.
- Strength Training: Strengthening the muscles involved in walking, particularly the calves, hips, and core, can help improve gait speed and stability.
- Balance Exercises: Simple balance exercises can improve proprioception and stability.
Comparison Table: Double Support Time Interpretation
| Factor | High Double Support Time (>40%) | Moderate Double Support Time (28-40%) | Low Double Support Time (<28%) |
|---|---|---|---|
| Significance in Seniors | May indicate increased fear of falling, impaired balance, or significant injury/frailty. | Generally a healthy, stable walking pattern. Reflects a good balance of caution and confidence. | May indicate a more dynamic, faster gait. For some seniors, could be a sign of excellent balance. For others, could indicate increased fall risk if not coupled with good strength and coordination. |
| Associated Gait Patterns | Shuffling gait, very slow walking speed, wider base of support. | Confident, measured pace. Stepping over objects is controlled. | Faster, more vigorous pace. Longer strides. |
| What to Do | Consult a physical therapist for an assessment. May benefit from gait training and assistive devices. | Continue with regular walking and balance exercises. Monitor for changes over time. | Can be a sign of fitness, but balance and fall prevention exercises remain important. |
Practical Exercises to Improve Balance
- Heel-to-toe walking: Walk with your heel directly in front of your toes. Use a wall for support initially.
- One-leg stand: Hold onto a sturdy surface and lift one leg, balancing for as long as possible. Gradually increase the hold time.
- Sit-to-stand: Without using your hands, stand up from a sturdy chair and then slowly sit back down. Repeat for a set number of repetitions.
- Side leg lifts: Stand and hold onto a countertop for support. Lift one leg out to the side, keeping it straight. Return to the starting position and repeat.
- Tai Chi: The slow, deliberate movements of Tai Chi can significantly improve balance and reduce fall risk in older adults.
Conclusion: A Healthy Gait in Perspective
In conclusion, a double support time of 30% is a very reasonable and healthy result for an elderly individual. It is not an indicator of poor mobility but rather of a stable, cautious gait that prioritizes safety, which is a natural and wise adaptation to the aging process. By understanding the underlying reasons for changes in gait and incorporating targeted balance and strengthening exercises, seniors can maintain a healthy and confident stride for many years to come. Ultimately, a good gait is one that is safe and allows for continued independence.
