Blood pressure and heart rate adjustment following acute Frenkel’s ambulatory exercise in chronic hemiparetics stroke survivors: a comparative study

: Background: Frenkel’s ambulatory activity has been routinely employed by physiotherapists for rehabilitation of gait coordination, how-ever, its immediate influence on blood pressure and heart rate has not been investigated. Objective To investigate the acute effect of Frenkel’s ambulatory activity on blood pressure and heart rate of chronic hemiparetic stroke survivors. Method Using a comparative study design, 60 chronic hemiparetic stroke survivors of varying onset of stroke, ≤6, >6-11 and ≥12 months were subjected to a 2-minute Frenkel’s ambulatory activity on marked footsteps (from standard adult described foot-steps). Participants were assessed for both blood pressure and heart rate before and after the Frenkel’s ambulatory activity. Results Blood pressure and heart rate significantly increased (p<0.05) following Frenkel’s ambulatory activity in all the 3 categories of stroke onset above baseline. However, there was no significant difference (p>0.05) across the onsets in both blood pres sure and heart rate responses. Conclusion The outcome of this study indicated that Frenkel’s ambulatory activity has the propensity to increase blood pressure and heart rate of hemiparetic stroke survivors irrespective of the onset of stroke. We recommend a pre, within and post-activity monitoring of stroke survivors while subjecting them to Frenkel’s ambulatory activity. This study is a comparative observational study of the pre/post test influence of Frenkel’s ambulatory activity on heart rate and blood pressure in hemiparetic stroke survivors undergoing rehabilitation. The study was conducted in the gymnasium of the Department of Physiotherapy, Aminu Kano Teaching Hospital (AKTH).The study was approved by the ethics com-mittee of AKTH.


Introduction
Gait is an organized motor activity essential for the performance of activities of daily living.Gait activity in humans is made possible through a sensory-motor control systems of complex integration.The exact cortical, subcortical, and spinal control mechanisms of gait remain unclear 1 .Stroke interferes with the spe-cialized organization of these neural control systems extending the period of ambulatory impairment.These results in physical inactivity and deconditioning which accelerate declines in neuromuscular function and cardiorespiratory endurance, increase the risk for cardiovascular disease and increase disability 2 .
Impaired walking ability is a hallmark of the residual deficit following stroke.At the early stage of stroke, the paresis of the lower-extremity secondary to impairment of muscle activation decreases the likely effort to propel the limb to swing and the ability to use the limbs as a base of support during stance 3,4 .As time from stroke increases beyond the early post-stroke period, motor control, muscle strength (force-generating capacity), and walking ability gradually improve 5 .Persistent gait inefficiency might still be present as a result of residual impairment and development of other secondary impairments 6,7 .Coupled with paresis, stroke disrupts selective voluntary control and can leave the

Corresponding author:
Lawal Isa Department of Physiotherapy, Faculty of Medicine, Bayero University, Kano GSM: 07033318835 or temporarily +27844061776 E-mail: isalawal30@yahoo.compatient with primitive patterns of muscle action and spasticity 8 .Additionally, disuse muscular atrophy might compound the initial neurological deficit, and such muscle weakness could prevail for longer period irrespective of the functional recovery attained during the acute phase 9 .The resulting effect of these impairments on walking is reduced speed and endurance, poor balance and a seemingly, asymmetry during gait.
Stroke does not often occur alone as, patients with stroke present with other forms of medical conditions 10 .These conditions could pre-date the stroke or post-stroke (as complications).About 175% of stroke survivors have been reported to present with cardiac disease 10 .Physical activity places greater energy demand on cardiovascular system of hemiplegic patients than apparently healthy individuals.Stroke survivors with pre-existing or post-stroke cardiac disease might be at increased risk for exertion related cardiac complications 10 .Such complications, might delay or inhibit participation in a therapeutic exercise program, complicate the rehabilitation and/or extend long-term post-stroke course of care.The overall effect is, limiting the ability of the patient to perform functional activities independently 11-14 .Frenkel's exercise is an aerobic exercise that consists of a series of carefully planned activities, aimed at making the patient employ what is left to him/her of muscle sense, in order to prevent further decline of the muscle sense or even effect an improvement 15 .The exercise was primarily developed to treat sensory ataxic patients having complaints of loss of impulses and lack of voluntary control mechanism 15 .Subsequently, the exercise was adopted in the rehabilitation of a number of conditions with impaired gait, balance and coordination, including stroke.Gait disorders in stroke could be compounded by sensory loss apart from the motor impairments 16 .The sensory impairments could include proprioceptive loss leading to inability to be aware of position of the limbs in space and thus, where to place them 17 .The concept of Frenkel's exercise is to compensate for that loss with the visual system which can update the central nervous system about the position of the limbs in space and their direction of movement, thereby, contributing to balance and improving gait pattern.Detailed administrative protocol of the exercise has been explained elsewhere 15,18 .The ambulatory part of the exercise is the most advanced stage of the exercise and it is characterized by a well-coordinated exercise, with patients required to place their feet in marked footprints as they advance in walking.This activity requires a lot of concentration, coordination and endurance and may serve as a threat to the cardiovascular system, especially in hemiparetic stroke survivors.This is because paretic gait is known to be associated with a highenergy demand compared with the non-paretic 19,20 , and stroke subjects' show poor endurance 19,21 .Frenkel's exercise has become a popular exercise protocol among therapists, administered mainly for gait correction and coordination.However, there has been no documented literature on the potential cardiovascular adjustments following Frenkel's ambulatory exercise.Our study investigated the effect of Frenkel's ambulatory activity on selected cardiovascular parameters (specifically, blood pressure and heart rate) with an aim to identify to what extent these parameters are influenced by the acute effect of the activity.

Participants
Sixty male and female chronic hemiparetic stroke survivors were recruited to participate in this comparative study.Participants were all recruited from the outpatient physiotherapy clinic of Aminu Kano Teaching Hospital,Kano.Recruitment of participants was specifically targeted at engaging 3-categories of hemiparetic stroke survivors based on their time since stroke (or stroke onset).
These categories are: ≤ 6-months (group A),>6-11 (group B), and ≥12 (group C) with each group having a total of 20 participants.Recruited participants were found to conform to study inclusion criteria which include: a) A history of cardio-vascular accident (CVA) of at least 3-months of onset.b) Unimpaired cognition and having positive motivation.c) Ability to walk a distance of 10m (walking aids are permitted, but not the help of another person).d) Ability to stand from sitting without help and walk a minimum of 10m independently prior to CVA. e) Signing a written informed consent.Similarly, participants were excluded if they present: 1) have had some sort of Frenkel's activity earlier.2) Receptive aphasia.3) Medical instability (e.g.uncontrolled blood pressure, arrhythmias, and unstable cardiovascular characteristics).4) Participants with visual impairments such as blurred vision, long or short sightedness.5) A history of fracture or significant orthopaedic surgical procedure in the upper and/ or lower limb interfering with patient's functional ability to walk prior to or post-CVA.

Administration of Frenkel's ambulatory exercise
A 2-minute walk in a coordinated fashion guided by marked footprints was performed by each participant (monitored individually).This is chosen based on the characteristic of the study population 23 .The 2-minute walk test was specifically administered to determine the immediate effect of the Frenkel's ambulatory activity.The ambulatory activity was performed on a flat concrete floor, with marked footprints of 9cm step width and seven degrees foot angle, these measurements have been reported as the average gait characteristic for adults 4 .
To commence the activity, participants were instructed to watch the movement they perform and to give full attention to the activity.They were asked to ensure that all movements are accurate and rhythmical.Each participant was asked to walk using his/her comfortable pace to ensure accuracy of placing each foot, on the marked footprints and to as much as possible maintain even tempo throughout the activity.Participants were encouraged from the beginning to the end of the exercise using phrases such as: a) you are doing well; b) you got it right; c) better foot placement and d) maintain the tempo.Activity was performed on separate days for each group of participants (i.e.≤6 months as A, >6-11 as B, ≥12 as C).

Data analysis
Data were analysed using descriptive statistics (mean±SD), dependent sample t-test and one-way ANOVA.Changes in blood pressure and heart rate were determined by analysing pre-and post-ambulatory values using dependent sample t-test and the percentage change was calculated using Microsoft excel.One-way ANOVA was used to determine differences in selected cardiovascular parameters in the three independent stroke onset categories.Analyses were conducted using Microsoft excel and SPSS (version 15.0) at a probability level of 0.05.

Results
A total of 60 stroke survivors participated in this study.Their mean age was 49.2±9.3 years and their mean BMI was 59.8±7.9 kgm-2.Thirty-eight (63.3%) of the participants were male, with thirty-two (53.3%) presenting with left-sided hemiplegia.However, the majority (90%) of the participants do not need walking aid, for ambulation (Table 1).

Pre and post blood pressure and heart responses
The differences in blood pressure and heart rate responses pre and post Frenkel's ambulatory activity was found to be significant for the both of the variables in all the 3 categories of stroke onset.In blood pressure both systolic and diastolic blood pressures demonstrated significant change (p<0.5) and this influence was also seen in the heart rate (Table 2).The outcome of the study equally, indicated insignificant differences in blood pressure and heart rate after adjusting for age and hemiplegic side (P>0.05)across onset of stroke (Table 3)

Discussion
We conducted a comparative study to investigate the effect of acute Frenkel's ambulatory exercise on blood pressure and heart rate of chronic hemiparetic stroke survivors.The outcome of this study suggests that acute Frenkel's ambulatory exercise significantly increases both blood pressure and heart rate measures of hemiparetic stroke survivors within each onset categories.However, while these changes are observed within specific durations of stroke onset, responses were not found to differ significantly across the duration of stroke onset.
The outcome of this study indicating heightened blood pressure and heart rate following acute Frenkel's ambulatory exercise, cannot be considered a normal physiological change following dynamic aerobic exercise because of two important reasons.4][25] Our study indicating a change in diastolic blood pressure negates the ordinary physiological variation seen in dynamic aerobic exercise under normal circumstances.Secondly, the implication of significant difference between pre and post intervention (in the variables) calls for a closer look into this activity (Frenkel's ambulatory exercise).This is because the physiological changes explained earlier are expressed with respect to normotensive population.The facts that stroke survivors have a known heightened risk of secondary cardiac complications and recurrent stroke, activities that task the cardiovascular system (such as the Frenkel's) must therefore be introduced with caution.
Several reasons can be advanced for the physiologi-  26 .This heightened level of fatigue could translate to an increased energy expenditure of hemiplegic gait which result from the inability to activate normal movement patterns 19 .The poor movement pattern has been linked with associated weakness, spasticity and abnormal central neural patterning of muscle activation 27 .Obviously, since Frenkel's ambulatory activity is geared towards correcting the movement pattern in stroke it might not therefore, be a surprise that its acute effect would alter physiological parameters significantly.Second, the gross physical deconditioning, age-associated decline in fitness and muscle mass, disproportionately large use of cardiovascular and metabolic capacity to produce ambulation 19,21,27 could all interfere with patients' physiological parameters to meet the challenge of this highly coordinated ambulatory activity when initially introduced.
A question might arise about why this difference when our sample are currently undergoing rehabilitation.An answer to this question has been provided by a previous study investigating exercise capacity in stroke survivors.The study monitored stroke survivors undergoing physiotherapy and occupational therapy 2 and 14 weeks post stroke.The study opined that therapy might be of insufficient intensity to produce a cardiorespiratory training impact 28 .It was discovered that on average in a physiotherapy session, 42% of the time was spent inactive in lying, 11% active in lying, 16% active in sitting and 31% active in standing and above all if it was present the aerobic component of a typical physiotherapy session lasted less than 3 minutes.Agreeably, with such a poor approach towards cardiorespiratory fitness being under therapy might not have put our participants in a good cardiorespiratory fitness to overcome the chal-lenge posed by the Frenkel's ambulatory activity.We compared the blood pressure and heart responses in the three categories of stroke survivors and found no significant difference in blood pressure and heart responses.This outcome might probably explain the lack of difference in fatigability and its consequence on cardiovascular response in stroke survivors which has been detailed in a study investigating the frequency and outcome of fatigue, its impact on functioning, and its relationship with depression in patients 3 to 13 months post-stroke.The outcome of which indicated that fatigue was not related to time post-stroke, stroke severity, or lesion location 27 .
These results must be interpreted with caution owing to small sample size and the absence of a control group.We cannot rule out selection bias considering the array of recruitment criteria used in this study and this might surely create under representation of certain medical comorbidities.On overall our concern is that we may over emphasize the impact of this ambulatory activity on blood pressure and heart rate of hemiparetic stroke survivors.However, the key information remains that when introducing activity of this characteristic to stroke survivors there is the need to appreciate the cardiovascular status of the patients and to introduce such activity cautiously.

Conclusion
The acute effect of Frenkel's ambulatory exercise significantly increases blood pressure and heart rate responses of stroke survivors irrespective of onset time post-stroke.The clinical implication of this outcome is that poor monitoring of stroke survivors at the initial introduction to Frenkel's ambulatory activity can pose a threat to cardiovascular parameters, therefore, therapists need to identify properly the cardiovascular status of the patients prior to exposing to this activity.We recommend a more extensive study to further substantiate our findings.
Group A, B & C= duration of onset (≤ 6, >6-11 & ≥ 12 months respectively),* SBP=systolic blood pressure, DBP=diastolic blood pressure,HR= heart rate, %∆= mean percentage change, *result is significant critical t19=1.73 at 0.05α level ProcedureThis study is a comparative observational study of the pre/post test influence of Frenkel's ambulatory activity on heart rate and blood pressure in hemiparetic stroke survivors undergoing rehabilitation.The study was conducted in the gymnasium of the Department of Physiotherapy, Aminu Kano Teaching Hospital (AKTH).The study was approved by the ethics committee of AKTH.
6) Other medical conditions severe enough to impair functional activities (e.g.walking).906907 African Health Sciences Vol 14 Issue 4, December 2014 African Health Sciences Vol 14 Issue 4, December 2014The physiological parameters including blood pressure and heart rate were measured at rest and post-Frenkel's ambulatory activity.The resting blood pressure and heart rate were measured with the participants seated comfortably at least 10 minutes prior to measurement using automated blood pressure monitor (Model: Omron BP710).The means of two consecutive readings of both blood pressure and heart rate were recorded, similarly, the procedure was performed immediately after completion of a single bout of the minute walk of Frenkel's ambulatory exercise; no room was permitted for a rest, so as to capture the immediate (acute) cardiovascular adjustments (in terms of blood pressure and heart rate).

Table 1 :
Physical and disease characteristics of subjects Group A, B & C= duration of onset (≤ 6, >6-11and ≥ 12 months respectively),* Values are in mean ± standard deviation, M/F=male to female count, R/F= right to left hemiplegia.†None of the comparisons of physical characteristics of participants were statistically significant at baseline in all the categories.

Table 2 :
Changes in blood pressure and heart rate following Frenkel's ambulatory exercise

Table 3 :
Differences in selected cardiovascular according to duration of stroke onset