Clinical efficacy and prognostic indicators for lower limb pedalling exercise early after stroke

1. Measurement of clinical efficacyis measured using the Motricity Index lower limb section. This is a widely used measure, with established validity and reliability for use after stroke. It is an ordinal score with six measurement levels within each of three categories for the lower limb. The three categories are: ankle dorsiflexion, knee extension, and hip flexion. For each movement, a score of 0, 9, 14, 19, 25, or 33 is given, where 0 is no movement, 19 is full range movement against gravity not against resistance and 33 is normal power.
2. Prognostic indicator measures:
2.1. Site of stroke lesion (determined from scan and liaison with medical team)
2.2. Degree of muscle weakness as measured by the Motricity Index (see clinical efficacy measures)
2.3. Ambulatory Capacity as measured by the Functional Ambulatory Categories: this scale is designed to give detail on physical support needed by patients for walking, so has clinical relevance, and is easy to use. It has established validity and reliability for use after stroke. It is an ordinal scale, patients scoring from 0 - 5, where 0 indicates a patient who is not able to walk or needs help of 2 therapists, and 5 indicates a patient who is independent in ambulation even on stairs.
2.4. Ability to control the trunk as measured by the Trunk Control Test: a short, simple measure of motor loss developed for use after stroke. Patients are asked to do four movements - rolling to their weak side, rolling to their strong side, sitting up from lying down and balancing in a sitting position. Each movement is scored according to ability, either 0, 12 or 25, leading to a total score out of 100. Validity and reliability have been established.

1. Onset and offset of EMG activity of antagonistic muscle groups during pedalling:
EMG activity will be recorded in quadriceps and hamstring muscles. The EMG system to be used is the Biometrics SX 230, Biometrics, UK. Baseline EMG activity in will be recorded as a voltage at 1,000Hz whilst the participant's foot is resting firmly on a box so that the leg is still and relaxed and the knee is in approximately 5 degrees of flexion, for 30 seconds. This will be undertaken for each leg in turn. EMG data (voltage) will be collected continuously during pedalling for 30 seconds at 50 rpm. EMG data will be rectified and then processed by a Technician. Baseline EMG values will be calculated as the mean ± 3 SD (standard deviations) during the 30 seconds baseline data collection period. Onset of activity in each of the four muscle groups will be defined as the time point during the 360 degree turn at which EMG voltage exceeds the mean baseline value plus 3SD for 20 data points (20 ms). Offset of activity in each of the four muscle groups will be defined as the time point during the 360 degree turn at which EMG voltage falls below the mean baseline value minus 3SD for 20 data points (20 ms). The time point for onset and offset of muscle activity in each of the four muscle groups will also be recorded as a function of the position of the pedal during the 360 degree turn as one channel of the DataLINK will be making recordings of angle of turning synchronously with EMG data. Thus in addition to timing of onset and offset of muscle activity we will also be able to relate this to the position of the pedal and during the 360 degree turn.

2. Reciprocal activation of antagonistic muscle groups during pedalling:
By collection of EMG data as described above. Rectified EMG data for each antagonistic muscle pair will be analysed using the Spearman's correlation coefficient. A r value of 1.0 indicates perfect correlation and therefore complete co-contraction, no reciprocal activation, of an antagonistic muscle pair. Whereas a r value of 0 indicates no correlation and therefore complete reciprocal activation of an antagonistic muscle pair. A negative correlation therefore indicates a better level of reciprocal activation of antagonistic muscle groups.