Comparison between the efficacy of underwater treadmill and over-ground treadmill training program on knee joint during gait cycle of stroke patients

Methods: Forty male patients suffering from post-stroke gait defi cits were assigned randomly into two equal groups: study group (A): Received underwater treadmill training program. Control group (B) received over-ground treadmill training program. Patients of both groups were assessed for knee Range of Motion (ROM) during gait cycle using slow motion video and goniometer iPad application. Assessment was done before and after four weeks of treatment for both groups.


Introduction
Stroke is a leading cause of death and disability worldwide, with an increasing incidence in developing countries [1]. The dynamic of bipedal gait is lost because of neurological injury with disabling consequences. Hemiparetic walking is characterized by a slow and highly ineffi cient gait, which is a leading cause of disability [2]. Stroke survivors commonly experience circumduction gait with mild to moderate spasticity that limits performance of normal stance and swing phases during the gait cycle. This is characterized by limited ability to perform hip-knee fl exion during overground walking.
Today, there is no specifi c therapeutic program that may enhance gait cycle in stroke survivors. Over-ground walking is commonly associated with poor performance as result of fear of falling. The essential physical properties of water has great therapeutic benefi ts as it eliminates the gravitational force and so that the only forces that act on the limbs are the muscle torque. Viscosity and hydrostatic pressure are able to support a body, reduce the fear of falling, and encourage balance [3].
The previous studies have found that aquatic therapy can improve muscular strength, endurance, equilibrium ability, and cardiopulmonary endurance because it is less burdensome on the lower limbs. It can provide stable training for those affected with stroke compared with ground exercises and can be helpful for achieving psychological stability [4].
The previous systematic reviews summarized that the water-based exercise for neurological disorder covers a wide variety, including resistance training, movement facilitation, motor control training, balance training, coordination training and other specifi c techniques indicated that stroke patients improved signifi cantly more in weight shifting ability, dynamic balance, and functional mobility as compared with the landbased intervention [5].
The aim of this study was to investigate the difference between underwater treadmill and over-ground Treadmill Training Program (TTP) in improving knee joint range of motion during the gait cycle of stroke patients.

Participants
The current study was done on forty male patients suffering from post-stroke gait defi cits. Inclusion criteria were: stroke patients could walk at least ten meters independently without the help of an assistive instrument, age of 45-60 years, Body Mass Index (BMI) ranged from 22-30kg /m 2 The participants were excluded if they suffered acute or recurrent stroke, had shortening or contracture in lower limb fl exors, moderate or severe spasticity as defi ned as modifi ed Ashworth scale equal or greater than grade three, any cognitive or psychiatric disorders or other neurological diseases which would affect the results of this study and chronic neglected patients.

Interventions
Forty male patients with post-stroke gait defi cits were included in the current study. The patients were recruited from local hospital and randomly divided evenly into two groups of twenty patients: study group A and control group B.
Randomization was performed at 1:1 ratio considering the order of enrollment in the trial without considering their modifi ed Ashworh scale scores.
Before enrollment, all participants were asked to read and sign a consent form that was approved by local ethical committee. Study group A. The patients received underwater treadmill training program in a therapy pool with a water depth adjusted to the chest level (Xiphoid process) by using movable fl oor pool [6]. The temperature of the water was adjusted to 34°C-36°C with an air temperature of 24°C, the program consisted of fi ve minutes warm up-period followed by 30 minutes of strengthening, trunk mobility and balance exercises and 15 minutes aquatic treadmill training (Begin at an individual's comfortable turning speed on level ground, increased by increments of 0.05 m/s every 5 minutes as tolerated), fi nally ten minutes Cool-down period. Control group B. The patients received over-ground treadmill training program consisted of fi ve minutes warm up-period followed by 30minutes of strengthening, trunk mobility and balance exercises and 15minutes over-ground treadmill training (Begin at an individual's comfortable turning speed on level ground, increased by increments of 0.05 m/s every 5 minutes as tolerated), fi nally ten minutes Cooling-down period [7].

Outcome measures
All assessment methods were valid and reliable. All patients were passed into the following assessment: (I) knee joint (ROM) during the gait cycle: by using slow motion video and goniometer iPad application: The iphone 6 plus camera adjusted to view the whole markers in sagittal plane, captured knee fl exion and extension from lateral view during the gait cycle [8]. The video was taken while the patient walks on overground treadmill. The range of motion detected over the screen shoot by using iPad goniometer application [9].

Statistical analysis
Descriptive statistics and unpaired t-tests were conducted for comparison of age between both groups. Normal distribution of data was checked using the Shapiro-Wilk test for all variables. Levene's test for homogeneity of variances was conducted to test the homogeneity of knee ROM between the study and control groups. Unpaired t-test was conducted for comparison of knee ROM between the study and control group. Paired t-test was conducted for comparison between pre and post treatment in each group.
The level of signifi cance for all statistical tests was set at p<0.05. All statistical analysis was conducted through the Statistical Package for Social Studies (SPSS) version 25 for windows (IBM SPSS, Chicago, IL, USA). The signifi cance or alpha () level of the study was set to 0.05 (5%) [10]. Statistical signifi cance was set at the (p<0.05) level of probability [11].

Ethical statement
The research protocol has followed the tenets of the

Basic characteristics of the patients
Subject characteristics were demonstrated in Table 1. There was no signifi cant difference between groups in age, weight, height, BMI and duration of illness (p>0.05).

Effect of treatment on knee joint ROM in initial contact, mid stance and pre swing
Within group comparison: There was a signifi cant increase in knee fl exion in initial contact and knee fl exion in pre swing post treatment compared with that pre-treatment in the study group (p>0.001). Also, there was a signifi cant increase in knee extension in mid stance post treatment compared with that pre-treatment in the study group (p>0.001). While there was no signifi cant change in knee ROM in the control group between pre and post treatment (p>0.05) ( Table 2).

Between two-group comparison:
There was no signifi cant difference between groups pretreatment (p>0.05). Comparison between groups post treatment showed a signifi cant increase in knee fl exion in initial contact and pre swing and signifi cant increase in knee extension in mid stance of the study group compared with that of control group (p<0.05) ( Table 2).

Discussion
The major fi ndings of the current study highlighted that The results are consistent with the results of [12], summarized that the water-based exercise, for stroke patients, showed more signifi cant improvement in weight shifting ability, dynamic balance, and functional mobility as compared with the land-based intervention. Moreover [13], concluded that hydrotherapy exhibited signifi cant effects on improving postural balance in chronic stroke patients than in sub-acute patients with stroke and showed improvement in paretic knee extensor strength.
The water environment serves as a partial support for the body, allowing for mobilization of joints. Also, aquatic therapy provides motor and sensory stimuli that can potentially improve balance and muscle function [14]. Furthermore, the buoyancy of water might allow stroke patients to move with less effort and across movement planes that would be diffi cult during overground gait training without assistance [15].
The results are consistent with previous work [16] confi rming that aquatic training in stroke patients signifi cantly improves motor functions. These improvements can be attributed to the water environment, which partially supports the body, thus facilitating whole body movements.
Water is a fl uid medium, with medium density and viscosity, which reduces the speed of movement, and because of this, when an individual enters a pool with water at waist level, approximately 50% of the weight is reduced, in addition to reducing gravity, in water, the probability of falling decreases by 21%-23%. This means that people experience greater mobility in water with greater range of motion [17].
These results are in agreement with [18], proved that four weeks of aquatic trunk exercise could improve the gait factors signifi cantly in terms of walking speeds, walking cycles, affected-side stance phases, affected-stride lengths, improvement in weight shifting ability and stance-phase symmetry indices, respectively.
The results are in agreement with [19], proposed that  These results are in agreement with [20],

Conclusion
The results of this study concluded that underwater treadmill training program is more effective than over-ground treadmill training program on improving knee joint stability and mobility during the gait cycle which could improve gait kinematic and allow more weight shifting ability and stancephase symmetry on paretic limb in stroke patients.