Functional Training for Lower Extremities in Stroke Survivors: A Scoping Review

Engaging in meaningful and repetitive goal-oriented functional tasks can effectively enhance neuroplasticity and facilitate recovery following a stroke. This particular approach has primarily been studied in relation to functional outcomes and has predominantly focused on late subacute and chronic stroke patients. However, there is a lack of information regarding the standardized protocol of lower extremity functional training, its constituent elements, and its impact on motor recovery during the early subacute phase of stroke. The aim of this study was to examine the available evidence related to the intervention protocol of lower extremity functional training in order to identify common training elements and assess their impact on motor and functional outcomes in stroke survivors. A systematic search was conducted on PubMed and Scopus, covering the period from 2000 to 2022. A total of 1786 articles were retrieved and screened based on predefined inclusion criteria. A total of 36 articles were included in this review. The primary findings were classified into categories such as intervention protocols for functional training and their constituent elements, outcome measures utilized, minimal clinically important differences (MCID) reported, and the conclusions drawn by the respective studies. Only a limited quantity of studies reported on the intervention protocol of lower extremity functional training. The majority of these studies focused on the efficacy of functional training for enhancing gait and balance, as evaluated through functional outcome assessments, particularly in the context of chronic stroke patients. In most studies, the evaluation of outcomes was typically based on statistical significance rather than clinical significance. In light of these findings, it is recommended that future studies be conducted during the early subacute phase of stroke to further investigate the impact of functional training on motor outcomes. This will contribute to a broader understanding of the benefits of functional training in facilitating motor recovery in the lower extremities and its clinical significance in stroke survivors.


Introduction And Background
Stroke is a significant contributor to disability leading to functional and motor deficits [1].Impairments in motor function of the lower limb following a stroke are prevalent and can exhibit varying degrees of severity and presentation, contingent upon the location and size of the lesion.Post-stroke individuals commonly endure a range of disabilities and impairments that significantly impact their postural stability, mobility functions, and activities of daily living [2].Commonly implemented rehabilitation interventions to augment recovery in stroke patients include task-specific training, robot-assisted training, constraint-induced movement therapy, body weight-supported treadmill training, balance training, gait training, functional electrical stimulation, mirror therapy, and virtual reality [3,4].
Functional training is a therapy approach centered around the task-oriented practice of goal-directed functional tasks.These functional tasks emphasize the engagement of muscle groups working in unison, rather than isolated muscle movements [5].Functional training includes purposeful, repetitive, intensive mass practice of meaningful functional activities to the patient.Engagement in functional training within an enriched environment aids in enhancing neural plasticity and facilitating motor recovery [4].The impact of functional training on functional abilities like gait, balance, and sit-to-stand has been extensively investigated [6,7].While motor recovery is a crucial aspect, evidence suggests that functional training has been extensively examined in terms of functional recovery rather than motor recovery in stroke survivors [8,9].Studies indicate that there exists a distinction between functional recovery and motor recovery and these distinctions are measurable with functional and motor outcomes [10,11].
Functional training is administered in various forms within stroke rehabilitation such as repetitive functional task practice, repetitive task practice [12], task-related training [13], task-oriented therapy [14], and circuit class training [15].The intervention protocol by Dean et al. has been utilized as a reference in some studies [16][17][18].However, the documentation of standard intervention protocol for lower extremity functional training remains unclear in the existing literature.The majority of the studies on functional training have been conducted on chronic and late subacute stroke populations [19].There is a dearth of research on the early subacute stroke population regarding lower extremity functional training, although Liu et al. suggest that implementing interventional strategies within two weeks of the subacute stroke phase during early rehabilitation may lead to improved outcomes [20].
The concept of minimal clinically important difference (MCID) is employed to denote the smallest minimal change that signifies an improvement in the patient's perspective.It is worth noting that while treatment effects can be identified through statistically significant differences, it is not always the case that statistical difference corresponds to practical or clinical significance.Outcomes defined using MCID rather than statistical significance can capture changes in outcomes that are clinically relevant and practical in the context of health care treatments [21].In the realm of functional training, few studies have taken into account the MCID when explaining the outcomes [17,[22][23][24][25].
The aim of this scoping review was to address several questions.Specifically, we sought to determine whether functional training has been studied in the early subacute, late subacute, and chronic stroke populations.Additionally, we aimed to explore whether there exists a standardized protocol for lower extremity functional training as well as whether there are common exercises present in the training.Furthermore, we aimed to assess the outcomes of the studies focused on functional or motor recovery of the lower extremity and whether these outcomes were evaluated in terms of MCID or solely based on statistical significance.

Review Methodology
The Arksey and O'Malley scoping review methodology framework [26], as well as the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews guidelines, were employed for the reporting of scoping review in this study.
The scoping review research questions are as follows: (i) Is there a standardized protocol or common elements in lower extremity functional training, (ii) Has functional training been studied in all stages of stroke, (iii) What are the common functional and motor outcomes used to assess the effect of lower extremity functional training in stroke survivors, and (iv) Are the reported outcomes based on clinically meaningful changes (MCID) or solely on statistical significance.

Identifying Relevant Studies
To identify relevant studies, we formulated a search strategy and conducted searches in two electronic databases PubMed and Scopus.We used keywords such as "Stroke", "Cerebrovascular Accident", "Hemiplegia", "Task-oriented training", "Task-specific training", "Functional training", "Circuit class training", "Rehabilitation", " Conventional Physiotherapy", "Walking", "Gait", "Balance", "Postural control", "Sit to stand" and "Weight bearing".The search was limited to articles published between 2000 and 2022.Boolean operators and medical subject headings (MeSH) terms related to these keywords were used in the search.

Study Selection
For the study selection process, we applied the following inclusion criteria: articles published in the English language, study participants as stroke survivors, intervention as functional training for lower extremity, outcomes studied for functional and motor recovery, and full-text articles of randomized controlled trials.Two independent reviewers (MJ, SR) conducted an initial screening based on the title and abstract of the records.After removing duplicates, the full text of the selected articles was read.Any conflicts in the screening and study selection process were resolved by a third reviewer (SV/JS).The data was managed using the Rayyan application reference manager [27] and Microsoft Word (Microsoft Corporation, Redmond, Washington, United States).

Charting the Data
The data from the articles was extracted, including the author, year of publication, days post-stroke, stages of stroke, sample size, intervention received by the control and experimental groups, intervention duration, outcome measures, and study conclusions.

Collating, Summarizing, and Reporting the Results
After discussing and interpreting the data, the final results were summarized into different categories.The results were reported in subcategories based on the stages of stroke studied, whether the functional training implemented had a standard protocol or common elements, the functional and motor outcome measures, and the reported outcomes for clinical and statistical significance.

Results
A total of 1786 articles were obtained from the databases of which 657 duplicate articles were eliminated.The title and abstract of 1129 articles were assessed.After the initial assessment, 1093 articles were excluded.Based on the inclusion criteria, 36 full-text articles were read and included in the review.The process of selecting studies for the review paper is presented in Figure 1

Intervention Protocol and its Components for Lower Extremity Functional Training
The intervention protocol and its components for functional training of the lower extremities were described in nine studies involving stroke patients.These studies include those by Salbach et al. [18], Mendoza et al. [22], Kuberan et al. [23], Choi and Kang [28], Mudge et al. [29], English et al. [30], Dean et al. [31], Ma et al. [32], and Martins et al. [33].The various components of lower extremity functional training that were investigated include walking in 29 studies, balance in 23 studies, sit-to-stand in 13 studies, stair climbing in six studies, and weight bearing in three studies.
Walking was trained in different forms such as walking on various surfaces, comfortable and fast walking, obstacle course walking, Indoor and outdoor walking, carrying objects while walking, tandem walking, backward walking, and walking on a treadmill [18,22,23,[28][29][30][31].Stepping exercises involved the use of blocks and stair climbing [18,28,[30][31][32].Activities in the standing position included standing with feet close together, in a tandem position, standing on one leg with support, standing within parallel bars, reaching tasks, and marching in place [28][29][30][31].Activities in a sitting position included reaching tasks and sitting on a Swiss ball [23,30,31].Sit-to-stand practice was performed using chairs of varying heights [22,23,[29][30][31]33].The exercises were progressed gradually by increasing the number of repetitions or the difficulty of the tasks.However, it was observed that some studies did not provide detailed information about their intervention protocols, and in many cases, the specific functional tasks used were not clearly documented among the studies [17,34,35].
The study characteristics for the 36 included studies in the scoping review can be found in Table 1.

Discussion
In the scoping review, we investigated four distinct research inquiries.Out of the 36 studies examined in the review, only nine studies provided comprehensive information regarding the interventional protocol.The protocols employed varied across the studies.The training was administered in a structured manner, such as circuit class training or customized to target specific functions of the lower limb.Functional training encompassed a range of activities conducted in seated and standing positions, including practicing sit-tostand and walking.Based on the findings of the review, it can be concluded that an intervention protocol for functional training is necessary to facilitate the generalization of exercises for individuals with subacute and chronic stroke respectively.
Functional training has been assessed for its effectiveness, supported by its physiological basis of influencing neuroplasticity and motor recovery.However, the majority of studies have focused on functional outcomes rather than motor recovery.While motor recovery is a crucial aspect of stroke rehabilitation, functional recovery has been the primary outcome of interest in most clinical trials involving functional training interventions.Functional abilities may also improve through compensation, which entails the adoption of alternative behavioural strategies to complete tasks or achieve goals.It is important to differentiate motor recovery from compensation [58].
In addition to sit-to-stand and stepping, mobility is an essential function of the lower extremity, which is also involved in postural control and manipulating tasks [6].A standardized protocol can be valuable for implementing and comparing interventions that target different functions of the lower extremity.Impaired postural control often results from disrupted muscle activation in the lower limbs following a stroke.The lower limbs play a critical role in maintaining balance, and their compromised function due to post-stroke impairments can lead to instability and an increased risk of falls.Postural-related activities are pivotal in eliciting muscle contractions in the lower limbs and ensuring stability and balance [59].Oddsson conducted a study emphasizing the connection between postural control and muscle activation in the lower limbs [60].Dean et al. illustrated the role of lower extremities in postural control during sitting reaching tasks [61].Electromyography (EMG) findings from the study support the consistent ability of stroke patients to elicit muscle contractions in the anterior tibial and soleus muscles in the paretic lower extremity following training in seated reaching tasks [61].Consistent with these findings, several studies have incorporated reaching tasks in sitting and standing positions, with the anticipation of improvement in lower extremity motor control [30,31].
Manipulation or handling of objects is widely recognized as an upper extremity function.The training of functional tasks involving grasping, releasing and manipulating objects has been commonly employed in hand rehabilitation following a stroke [62].Meanwhile, in our everyday lives, the lower extremity is also utilized for object manipulation.Activities such as using the lower limb to move footwear, retrieving objects from the floor with the lower limb and kicking or moving objects using the lower limb could be classified as manipulative tasks of the lower limb.Davies recommends tasks such as holding and moving a ball beneath the paretic lower limb in order to elicit muscle contraction [63].A study conducted by Ramachandran et al. demonstrated that training the paretic upper limb to maintain a position on an unstable surface resulted in proximal muscle contraction of the upper limb in stroke patients during the acute phase [64].However, it is worth noting that such activities were not observed in the functional training tasks employed in stroke rehabilitation.
Initiating rehabilitation in the early stages following a stroke may prove to be efficacious and advantageous for patients as it has the potential to enhance neuroplasticity and consequently promote recovery [20].Clinical trials have predominantly included individuals from the chronic stroke population as study participants, in comparison to the late subacute and early subacute stroke populations [19].There exists a necessity for clinical trials to ascertain the impact of functional training on the early subacute population, as this specific time period presents an increased likelihood of neuroplastic changes, which in turn aids in facilitating improved recovery and outcomes.The literature is lacking in substantial evidence regarding the effectiveness of lower extremity functional training on motor outcomes.Among the 36 studies included in the review, three studies have only utilized the Fugl-Meyer assessment scale of motor recovery to substantiate the outcomes of the study [16,34,37].
In certain studies, the analyses implemented when assessing the study results incorporated the concept of MCID [17,[22][23][24][25]30,51,55].MCID signifies the smallest alteration that holds clinical significance from the patient's perspective and it may accurately reflect the efficacy of a treatment or intervention.By incorporating the MCID values into the results, researchers can gain a more comprehensive understanding of the effectiveness of lower extremity functional training following a stroke.

Strengths and Limitations of the Study
The review presents comprehensive details on various categories such as post-stroke duration, sample size, intervention methods employed in the experimental and control groups, outcome measures, reports of MCID, and conclusions drawn from the individual studies.A limitation of this study is the absence of a quality assessment for the included studies.

Conclusions
A diverse range of functional tasks involving the lower extremities, such as transitioning from a seated to a standing position, engaging in reaching activities while sitting or standing, bearing weight while standing, and practicing walking in various forms, has been previously integrated into functional training.Functional activities for the lower extremities can involve tasks of manipulation and dynamic control of posture while standing.To determine the effectiveness of functional training in stroke survivors, it is imperative to establish a standardized protocol.Functional training in the chronic phase of stroke has been the focus of most studies comparing its efficacy to the subacute phase.The majority of these studies have emphasized functional outcome measures to demonstrate its effectiveness.However, there is a lack of evidence regarding the efficacy of functional training on the motor outcomes of the paretic lower extremity in the early subacute phase of stroke.Future clinical trials and reviews can be conducted to contribute further to the existing evidence and explore the clinical implications of lower extremity functional training in the early subacute phase of stroke.
, using the PRISMA flow diagram.

FIGURE 1 :
FIGURE 1: PRISMA flow diagram of the study selection process PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses the MCID values.Salbach et al., 2004 [18] E -239 days, C -217 days post stroke (Chronic) N -91 (E -44 and C -E -Task-OrientedTraining, C -Functional tasks training for upper 6 weeks Berg Balance Scale, Timed Up and Go Test, 6-Minute Walk Test, Five-The study concluded that taskoriented training was effective in improving walking distance and 2024 Jharbade et al.Cureus 16(4): e58087.DOI 10.7759/cureus.Walk Test, 10-Metre Walk Test, Timed Up-and-Down Stairs.The study suggested that circuit class therapy can improve walking abilities in chronic stroke patients.Fast gait velocity reached to MCID Values in task group.Up-and-Go Test, Fall Efficacy Scale.Task oriented exercises with altered sensory input was found to be effective in improving dynamic balance and functional mobility and reduction in fear of fall.Clinically meaningful changes (MCID) was found in DGI scores in the experimental group.Kim et al., , Timed Up-and-Go test, 6-Minute Walk Test, Functional Ambulation Classification.The Study concluded that task oriented circuit training improve the gait in subacute stroke patients.Clinically meaningful changes were noted in 6MWT in task oriented training group.Ingrid et al., Up-and-Go Test, Timed Balance Test, Modified Stairs Test, and Letter Cancellation Task.Task oriented circuit training was effective to improve gait abilities in late subacute phase of stroke. in chronic stroke patients.2024 Jharbade et al.Cureus 16(4): e58087.DOI 10.7759/cureus.orientedVRT combined with TOT 2024 Jharbade et al.Cureus 16(4): e58087.DOI 10.7759/cureus.

TABLE 1 : Summary of 36 studies included in the scoping review investigated for lower extremity functional training in stroke survivors FMA
: Fugl Meyer assessment scale of motor recovery after stroke; BBS: Berg Balance scale; 6MWT: 6-Minute Walk test; 10 MWT: 10-Metre Walk test; TUG: Timed Up and Go test; SIS: Stroke Impact Scale; FAC: Functional Ambulation Category; DGI: Dynamic Gait Index; FES: Fall Efficacy Scale; FRT: