irstly the goal of being able to walk again post stroke is not realistic for every stroke client and is dependent on many variables including; severity of the stroke, motor recovery, cognition and medical history. However for those that are working towards the goal of walking again are you doing enough? How much is enough? Does it really matter how often you walk or for how long?
There is now research to support the answers to all those questions, to improve walking you must be practising walking, this can either be on a treadmill, with body weight support, assistance from therapists or carers or aids. Large amounts of repetitions are critical to enhance plastic changes in neural circuits. Repeated task specific practice during motor skill acquisition has been shown to increase dendritic growth, synaptic strength, number and neuronal activity in the brain or spinal circuits, resulting in long lasting alterations (improvements) to motor performance. Evidence shows that there needs to be at least 1000 to 2000 steps per therapy session or at least 2000 steps per day at home (2000 steps is approximately 1km for fairly normal stride pattern) to produce significant changes or improvements in your walking.
Walking at a speed that is 85% of predicated maximum HR is also needed to see change, another target is to take 80 steps per min to achieve change. Increased neural activity is needed to drive the muscular and cardiovascular systems. High intensity activity may increase synaptic connectivity strength. This has been seen in both animal and human studies where short bursts of high intensity stimulation to the nervous system results in rapid and sustained increases in synaptic efficacy. In high intensity exercise endogenous neuromodulators facilitate performance in the spinal and supraspinal circuits. So when walking more significant improvements are made when training at higher speeds.
Results are the same whether the walking has been on a treadmill or overground. However our bodyweight support treadmill offers the ability to walk safely reducing the risk of falls. It also ensures that you are working hard enough to achieve the 85% of you predicted heart rate max to ensure the neuromuscular adaptations. It is much easier to slow down and reduce your effort levels when walking overgound, however the treadmill keeps going at a set speed so you have to keep working hard.
If your goal is to improve your walking you need to be walking approximately 2000 steps a day and walking at a speed that is challenging your cardiovascular system (making you breathless) several times a week.
Hornby et al, 2011, Topics in stroke rehabilitation. Importance of Specificity, amount and the intensity of locomotor training to improve ambulatory function in patients post stroke.