What is the purpose of the Biofeedback Graph and how can I use it?
The Biofeedback Graph is an interactive tool to confirm that your patient remains active during the Lokomat session. In combination with the high number of repetitions achieved during a training session, this effort results in high training intensity.
The purpose of Biofeedback is to enable both the clinician and the patient to visualize objectively the amount of effort the patient is contributing during a gait cycle. Thus, to provide feedback on the performance of the patient.
How is it displayed?
Biofeedback Graph can be displayed at any moment of the Lokomat session on the therapist screen if you click on the button Biofeedback Graph on the bottom tab of the Lokomat training screen (Figure 1).
To display the Biofeedback Graph on the patient screen and therewith enhance the patient’s attention and motivation, choose the Biofeedback Graph on the Library and add it to the therapy plan of your patient (Figure 2).
In both situations, the Biofeedback Graph is represented as a group of four graphs corresponding to the hip and knee activity for the left and right legs. Every graph has two lines: an orange line that indicates the level of activity during swing phase and a blue line indicating the level of activity during stance phase. On the vertical axis of the graphs (y axis), we can observe the amount of biofeedback units (the Lokocontrol software converts the force measured at the hip and knee joints), while on the horizontal axis (x axis), we can see time in seconds (Figure 3). On a functional level, this allows both the clinician and patient to know whether the patient is active at the appropriate time in the gait cycle.
Some recommendations for its application:
Based on the experience of Lokomat Users, here are some recommendations on how to benefit from the Biofeedback when treating a patient.
- Observing the baseline: When starting the training and while the patient is still relatively passive, visualize the Biofeedback Graph to see what a “passive” graph looks like.
It is important to remember that the absolute values of the Biofeedback Graph on the y axis may be different from session to session, that is why we recommend observing the session’s baseline during this passive phase.
- Assess the patient’s ability to increase effort: Once you have set a baseline, you can assess your patient’s ability to generate more gait-phase-appropriate force i.e., the patient helps with the movement (graph line goes up), or more gait-phase inappropriate activity, i.e., the patient resists the movement (graph line goes down).
- Use during training: Use the biofeedback screens during training to maximize your patient’s effort. Some examples:
- Adjust the Biofeedback Graph to show only 1 joint in 1 gait phase and get your patient to focus on that particular movement (Figure 2 and 4).
- Monitor your patient’s effort. You can use the Biofeedback Graph to make sure that your patient is training throughout the entire Lokomat session.
- Monitor the effects of your training adjustments. You can use the Biofeedback Graph to monitor any activation changes in relation to other treatment parameters (speed, loading, guidance force).
How do I Challenge the Patient During a Lokomat Therapy Session?
It is imperative that patients are challenged and that they participate actively throughout the whole Lokomat training session. This is important for the following reasons:
- Neuroplasticity can only occur when training is intense and the patient exerts maximum effort to accomplish the task.
- Motor learning is only possible when the patient is able to focus on the activity and assess his own performance.
- The training session will only be beneficial if it poses maximal physiological challenge (heart rate, muscle activation, blood pressure, etc.).
Below there are some tips from experienced Lokomat users on maintaining patient engagement throughout the training session.
You can adjust the training parameters to increase active patient participation in order to lead a challenging training session.
- Increase the gait speed to the maximum value where the patient still presents a good gait pattern.
- Decrease the Body Weight Support and support the patient only as much as he needs thereby ensuring the highest loading.
- Reduce the Guidance Force and challenge the patient himself to maintain the gait pattern.
Using Lokomat Features
In addition to changing the parameters in order to further challenge the patient, the Lokomat includes three important features designed to increase active participation:
- Training Programs: Add variety to the training and (a) keep the patient motivated throughout the training session, (b) challenge him to react and adapt to the changes the program creates, and (c) increase the variety of required movements to improve motor learning.
- Biofeedback graphs clearly illustrate phase appropriate and inappropriate activation; this information helps to pinpoint problem areas for the patient.
- Augmented Performance Feedback motivates patients by giving real-time feedback on the screen where they can see the effects of their effort in the gait training as they move their character through different challenging games and tasks.
Additionally, some Lokomat users support the use of external cues from the clinicians like, “hit my hand”, “kick this ball”, and “stand up straight”.
- While keeping a patient’s active participation up is vital to promoting recovery. It is also important to let the patient perform enough repetitions of the gait pattern. Therefore, pay close attention to the patient’s fatigue level, especially during the initial sessions in the Lokomat.
- If upright mobility is new to your patient, make sure to monitor his physiological response to the training.
How do I Define the Optimal Body Weight Support (BWS) Value for Individual Patients?
Initial configuration and ongoing adjustments of the BWS level during Lokomat sessions are key variables of gait training. The aim is always to provide a challenging training in a safe environment. In terms of BWS, this means finding the value where, enough support is provided to allow an upright position, yet reduced to a minimum to provide as much loading as possible.
The default starting value is 50% of the patient’s total body weight. This is based on the experience of Lokomat users who determined that most patients can start a training session at this value. However, it should be adjusted according to the patient’s ability and condition.
What are the criteria for determining the appropriate BWS value?
Whenever possible the maximal load should be applied to the patient. This maintains the appropriate sensory input during the gait cycle and challenges the patient’s entire body. Once a safe walk is achieved, we recommend reducing the BWS to <40% of total weight.
- Patient’s Knees: The main indicator to recognize if the value is correct is the patient’s ability to extend his knee. A sufficient amount of BWS should be maintained to allow the patient to achieve the appropriate gait pattern; pay attention to his ability to extend his hips and knees in stance phase and maintain his trunk upright during the gait cycle.
Training Progression: Once you find a level of BWS that allows for a good gait pattern with good kinematics, it is important to continue challenging your patient. This can be done either by gradually decreasing the amount of BWS, or by changing other gait parameters (e.g. speed, guidance force).
How do I define the BWS value at first?
During the first session you may not know how much support the patient needs, we therefore recommend the following:
- Start with walking in the air at the default value (50% of the patient’s body weight).
- Bring the patient down onto the treadmill until you reach a dynamic range of the BWS.
If, when lowering the patient, you cannot reach a dynamic BWS because the patient cannot carry 50% of his weight and the training session would not be safe (i.e. the knee does not extend during stance phase), then increase the BWS value.
- Once the patient is walking in a dynamic range, you can gradually reduce the BWS value while taking care to monitor the patient’s ability to extend his knees. The goal of reducing the BWS value is to support the patient only as much as he needs: we want maximum challenge for the patient but always in a safe training environment.
These recommendations are based on the feedback of experienced Lokomat users.
How do I Define the Optimal Speed for Each Patient?
The Lokomat starts with a default value of 1.5km/h. However, the optimal speed value in order to challenge patients during Lokomat therapy is different for each patient depending on his overall health condition, experience with the Lokomat as well as the individual training goal. Here we provide recommendations to support you defining the optimal speed for each patient.
How do I choose the appropriate speed value for the start if therapy and during training progression?
For the first training session the speed value should not be chosen too fast so that the patient has the ability to accustom to the device and follow the correct gait pattern; it should not be chosen too slowly to enable smooth movements. According to the feedback from experienced Lokomat users for the first training session a speed value between 1.5 and 2.0 km/h seems to be selected most frequently. For children the value is smaller, ranging from 1.0 to 1.5 km/h.
As soon as a safe and nice walking pattern has been established and the patient has been accustomed to walking in the orthosis, increasing the speed value is recommended to challenge the patient during the entire training session. We therefore recommend selecting the highest speed value at which the patient is still able to maintain a nice walking pattern. At the same time the speed should be chosen in accordance with the patients abilities to train for a complete training session.
When does it make sense to select higher or lower speed values?
Higher Speed Values
- Should be chosen when the gait pattern seems not physiological due to a low speed; increasing the speed might help the walking pattern to look “smoother” (Reisman et al., 2009; Tyrell et al., 2011)
- Imply more number of repetitions and increase the challenge for the patient during the training session. A challenge point optimization is required to provide sufficient afferent feedback and positively influence neuroplastic events in particularly early after injury (Pohl et al., 2002; Lamontagne & Fung, 2004; Miller et al., 2008; Outermans et al., 2010; Wada et al., 2010; Kuys et al, 2011).
- Make sure that the speed value is continuously increased over training progression to ensure a challenging walking session and support each patients potential for functional recovery (Andriacchi et al., 1977; Wagenaar & Beek, 1992; Wagenaar & van Emmerik, 1995)
- When the training goal is to enhance an “automatized” gait pattern during over ground walking a high speed value during the training session is required (Hesse et al., 2001; Kwakkel & Wagenaar, 2002).
- If patients are already able to walk but the training goal is to further increase their comfortable walking speed overground an increased speed value during Lokomat assisted training is required.
Lower Speed Values
Despite the fact that a high speed value is required in order to sufficiently challenge patients during their walking session lower speed values may be recommended:
- During the first training sessions, so that the patient can accustom to the orthosis and the walking pattern.
- The speed value needs to be reduced if it is too high for a patient to endure a whole training session.
- When the training requires time to focus on a specific movement for example consciously extending the knee during stance phase (Nogueira et la., 2013).
- For consciously activating muscle contraction and recruiting muscle fibers for specific muscle strength training.
- In patients with spasticity when starting the training session until the muscle tone regulates and adapts to the movement. A high speed can enhance a spastic reaction which could cause the orthosis to stop for safety reasons (Bohannon & Andrews, 1990).
What do I need to consider when changing the speed value?
- The step length should be adapted to the speed.
- The orthosis speed value should be adjusted (you can also us the automatic setting).
- The hip offset may require adjustments (towards extension).
- If the quality of the movement will be affected, e.g. heel strike at initial contact.
- The joints need to be able to support the increasing impact.