Short-term effects of static stretching versus myofascial release on hamstring tightness and lower extremity function in sedentary IT professionals: a randomized controlled trial

Abstract

Background

Prolonged sedentary work is associated with hamstring tightness, reduced flexibility, and functional limitations among information technology (IT) professionals. Comparative evidence for static stretching and myofascial release (MFR) in this population remains limited.

Objective

To compare the short-term effects of static stretching and myofascial release on hamstring tightness and lower extremity function in sedentary IT professionals.

Methods

In this two-arm randomized controlled trial, 30 IT professionals were allocated to static stretching (n = 15) or MFR (n = 15). Both groups received stipulated treatment five times weekly for three weeks. Active knee extension range of motion (AKE-ROM) was the primary outcome measure, and the self-reported Lower Extremity Functional Scale (LEFS) was the secondary outcome measure. Outcomes assessments were performed at baseline and days 8, 15, and 22. Data were analyzed using linear mixed-effects models examining group, time, and group-by-time interaction effects, with Bonferroni-adjusted post hoc comparisons.

Results

Both interventions significantly improved AKE-ROM and self-reported LEFS over time (all p < 0.001). A significant group-by-time interaction favored static stretching for AKE-ROM, with greater adjusted improvements at Day 15 (mean difference 3.27°, 95% CI 2.28–4.26) and Day 22 (5.20°, 95% CI 4.21–6.19; both p < 0.001). Although these between-group differences were statistically significant, the Day 22 difference remained smaller than previously reported minimal detectable change values for the AKE test. Self-reported LEFS scores improved significantly in both groups, with between-group differences remaining small and below clinically meaningful thresholds, indicating broadly comparable functional benefit. Sensitivity analyses adjusting for age and BMI yielded consistent findings. No adverse events were reported.

Conclusions

Both interventions improved AKE-ROM and self-reported LEFS over the study period. Static stretching demonstrated statistically greater improvements in AKE-ROM; however, the magnitude of this difference was smaller than published minimal detectable change values, and its clinical importance remains uncertain. Given the absence of a control group and the short follow-up period, findings should be interpreted cautiously.

Trial registration

ClinicalTrials.gov NCT06586554; initial release date: 04/09/2024.

Introduction

Musculoskeletal complaints are increasingly recognized as an important occupational health concern among information technology (IT) professionals and other desk-based workers [1–4]. Prolonged sitting, sustained postures, and limited movement during the workday have been associated with reduced muscle flexibility, impaired movement patterns, and an increased risk of musculoskeletal discomfort [3, 5–8]. In addition, sedentary behavior has been linked to functional limitations and a greater burden of musculoskeletal symptoms in workplace settings, highlighting its importance as a modifiable occupational risk factor [8–10].

Reduced hamstring extensibility has been associated with limitations in active knee extension range of motion (AKE-ROM), altered movement patterns, and difficulties during daily and occupational activities [6–12]. Among sedentary workers, prolonged sitting and reduced physical activity may further contribute to extensibility deficits and movement restrictions [3, 4]. Consequently, interventions aimed at improving hamstring flexibility may have both preventive and rehabilitative value in occupational health settings, particularly because workplace exercise programs have been shown to reduce musculoskeletal complaints and support functional capacity in desk-based employees [10, 13]. Improving hamstring flexibility in sedentary workers may also support workplace comfort, movement efficiency, and participation in occupational tasks, thereby contributing to occupational health and injury-prevention strategies.

Static stretching remains among the most commonly prescribed interventions for improving muscle extensibility and joint range of motion. Its therapeutic effects have been proposed to involve increased stretch tolerance, potential reductions in passive musculotendinous stiffness, and neuromuscular responses, although the relative contribution of these mechanisms remains incompletely understood [12–17]. Systematic reviews and meta-analyses generally support static stretching for improving flexibility, while recent evidence suggests that chronic stretching adaptations may depend on intervention duration, frequency, and loading characteristics [14–19]. These proposed mechanisms may be relevant in sedentary workers, although the factors contributing to reduced extensibility in occupational populations are likely multifactorial and not fully understood.

Myofascial release (MFR) has gained increasing attention as a manual therapy approach that may reduce perceived fascial restrictions, improve movement tolerance, and enhance movement performance [20–24]. Several mechanisms have been proposed, including potential alterations in fascial viscoelastic behaviour, neuro modulatory responses, reductions in passive tissue resistance, and changes in local circulation, although these mechanisms remain incompletely understood [21, 22]. Emerging evidence suggests that MFR may improve hamstring extensibility and movement-related outcomes, although findings remain heterogeneous and its comparative efficacy relative to established stretching approaches remains insufficiently clarified [20–25].

Despite increasing clinical use of both interventions, direct randomized comparisons between static stretching and myofascial release for hamstring tightness remain limited, particularly in occupational populations characterized by prolonged sedentary exposure. Much of the available literature has focused on athletic cohorts, asymptomatic adults, or laboratory-based acute responses, limiting translation to sedentary workers despite emerging workplace intervention research [9, 13, 24]. Moreover, prior studies have frequently emphasized flexibility outcomes while giving comparatively less attention to longitudinal functional responses, although both outcomes are clinically relevant to rehabilitation decision-making.

Addressing this gap is clinically important because identifying efficient and evidence-informed interventions for sedentary workers may support preventive rehabilitation strategies, workplace wellness initiatives, and management of work-related musculoskeletal dysfunction [8, 10, 13]. In addition, understanding whether intervention-related changes in hamstring flexibility are accompanied by parallel functional improvements may help inform treatment selection according to whether flexibility restoration or broader functional outcomes are prioritized.

Therefore, this randomized controlled trial aimed to compare the short-term effects of static stretching and myofascial release on AKE-ROM and self-reported lower extremity function scale (LEFS) among IT professionals with hamstring tightness using repeated-measures modeling. It was hypothesized that both interventions would improve hamstring tightness and lower extremity function over time. Based on previous evidence, static stretching was expected to produce greater improvements in hamstring flexibility, whereas functional improvements were anticipated to be broadly comparable between groups.

Materials and methods

Study design

This study was a two-arm, parallel-group randomized controlled trial with a repeated-measures design conducted to compare the short-term effects of static stretching and myofascial release (MFR) on hamstring tightness and lower extremity function in sedentary IT professionals. The study was designed as a randomized controlled trial with repeated assessments at baseline and follow-up time points to characterize intervention-related changes over time. The trial was designed, conducted, and reported in accordance with the CONSORT guidelines to ensure methodological rigor and transparency in reporting [20].

Study setting and participants

Participants were recruited consecutively from IT companies in the Delhi–NCR region following workplace screening sessions and educational seminars on hamstring tightness and musculoskeletal health. Leaflets highlighting the issue of hamstring tightness and the benefits of stretching and myofascial release were distributed among IT professionals, and banners were placed within company premises to raise awareness about the study. Recruitment and intervention procedures were conducted between January and December 2020 at the outpatient physiotherapy department of Prakash Institute of Physiotherapy Rehabilitation and Allied Medical Sciences, Greater Noida, India.

Eligible participants were male and female IT professionals aged 22–35 years engaged in sedentary desk-based work for at least 6 h daily and presenting with hamstring tightness confirmed by a positive active knee extension (AKE) test [21]. Normal hamstring flexibility was defined as knee extension within 20° of full extension; participants demonstrating greater restriction were considered eligible [21]. Participants were excluded if they had a previous lower limb musculoskeletal injury, neurological disorders affecting lower limb function, current structured flexibility training, or contraindications to manual therapy or stretching, and showed non-cooperation.

For participants demonstrating bilateral hamstring tightness, the limb exhibiting the greater restriction during screening was selected as the index limb for outcome assessment. The same limb was evaluated at all subsequent follow-up assessments.

For the active knee extension test, participants were instructed to lie in a supine position and flex both hips to 90 degrees while keeping the knees bent. They were then asked to grasp behind their knees with both hands to stabilize the hips at 90 degrees of flexion. Each participant was directed to actively extend the test knee at a time as far as possible. All participants provided written informed consent prior to enrollment.

Randomization and allocation concealment

Participants were randomized (1:1) using a computer-generated block randomization sequence prepared by an independent biostatistician not involved in recruitment, treatment, or assessment. Allocation was concealed using sequentially numbered opaque sealed envelopes opened only after baseline assessment. Because of the nature of the interventions, participant and therapist blinding was not feasible; however, all outcome assessments were performed by an assessor blinded to group allocation.

Interventions

Both groups attended five supervised treatment sessions per week for three weeks and received identical moist heat application before treatment. Standardization therefore focused on treatment scheduling, session frequency, intervention duration, and therapist supervision. Nevertheless, because the intervention techniques differed inherently, complete equivalence in treatment exposure and therapist contact time was not possible.

Static stretching group (SS group)

Participants received moist heat application to the posterior thigh for 20 min followed by static hamstring stretching (Fig. 1). Each stretch was held for 60 s and repeated three times with 60-second rest intervals per session, five sessions weekly for three weeks [22, 23].

Fig. 1.

Static stretching

Myofascial release group (MFR group)

Participants received the same pre-treatment moist heat application followed by therapist-administered cross-hand myofascial release directed to the hamstring fascia (Fig. 2). Each MFR application was maintained for approximately 60 s and repeated 5–7 times per session with brief intervals (10 s) between repetitions, five sessions weekly for three weeks [24–26]. Treatment scheduling and delivery conditions were standardized across groups.

Fig. 2.

Myofascial release

Treatment was delivered by a physiotherapist experienced in musculoskeletal rehabilitation who underwent protocol-specific training before study commencement. Pressure was applied to achieve a firm but comfortable fascial engagement without provoking pain or discomfort.

Participants were instructed not to initiate additional stretching programs, flexibility exercises, manual therapy treatments, or structured exercise interventions during the study period in order to minimize potential confounding effects.

Outcome measures

Primary outcome

Hamstring flexibility

Hamstring flexibility was assessed by active knee extension range of motion (AKE-ROM), measured using a standard goniometric procedure. The AKE test has demonstrated excellent intra-rater reliability (ICC = 0.91), low measurement error (SEM 2.6–2.9°), and acceptable minimal detectable difference (7–8°) in individuals with hamstring flexibility deficits [21].

Participants were positioned in supine with the hip stabilized at 90° flexion and were asked to actively extend the test knee as far as possible; the resulting knee extension angle was measured and recorded in degrees [21, 22].

AKE-ROM was assessed unilaterally on the limb demonstrating the greater flexibility restriction during screening. The same limb was evaluated at all subsequent assessments.

Secondary outcome

Lower extremity function

Lower extremity function was assessed using the self-reported Lower Extremity Functional Scale (LEFS), a valid and reliable patient-reported measure demonstrating excellent test–retest reliability (ICC = 0.94), high internal consistency (Cronbach’s α = 0.96), and strong responsiveness for detecting clinically meaningful functional change [27–29].

All outcomes assessments were conducted at baseline (Day 1) and post-intervention assessments were performed on days 8, 15, and 22 by a trained assessor who was blinded to the participants’ group allocation to minimize bias. Three independent values were recorded and averaged for each measurement to minimize random errors, improve reliability, and account for variability in individual readings.

Sample size estimation

Sample size was estimated a priori using G*Power (version 3.1.9.4) for the primary outcome (AKE ROM), assuming a repeated-measures between-group design, the effect size of 0.44 derived from a previous randomized clinical trial that reported comparable improvements in hamstring flexibility outcomes following therapeutic interventions for hamstring tightness [30], α = 0.05, and 80% power. Thirty participants (15 per group) were required to detect clinically meaningful between-group differences, yielding an achieved power of 81.3%. This sample was considered adequate for a three-week repeated-measures design subsequently analyzed using linear mixed-effects models.

The sample-size calculation was based on a repeated-measures ANOVA framework because mixed-model–based sample-size estimation was not readily available during the study planning stage. Linear mixed-effects modeling was subsequently selected for the primary analyses because of its greater flexibility in handling repeated observations, within-subject correlations, and longitudinal data structures.

Ethical considerations

Ethical approval was granted by the Ethics Sub-Committee at King Saud University (RRC-2020-04). Procedures conformed to the Declaration of Helsinki. Participant recruitment and data collection were completed before trial registration. Although registration was performed retrospectively (ClinicalTrials.gov: NCT06586554; initial release dated: 04/09/2024), the study protocol, outcome measures, intervention procedures, and planned statistical analyses were established before commencement of data collection and remained unchanged throughout the study. All participants provided written informed consent before participation, and they were assured of confidentiality and the right to withdraw from the study at any time without consequences.

Statistical analysis

Statistical analyses were performed using IBM SPSS Statistics, version 28 (IBM Corp. Released 2021. IBM SPSS Statistics for Windows, Version 28.0. Armonk, NY: IBM Corp), with significance set at p < 0.05. Descriptive statistics were used to summarize participant characteristics and outcome measures. Baseline characteristics were summarized descriptively using means, standard deviations, and between-group differences with 95% confidence intervals.

Linear mixed-effects models were selected because they provide flexibility for analyzing longitudinal repeated-measures data, account for within-subject correlations, and remain robust when handling repeated observations collected across multiple time points.

Primary analyses were conducted using linear mixed-effects models fitted by restricted maximum likelihood (REML) to evaluate the fixed effects of group (static stretching vs. myofascial release), time (baseline, day 8, day 15, day 22), and the group-by-time interaction on AKE-ROM and LEFS scores. Participant-specific random intercepts were included to account for within-subject correlation across repeated observations, and an unstructured covariance matrix was specified for repeated measures.

Estimated marginal means with Bonferroni-adjusted pairwise comparisons were used for post hoc comparisons when significant model effects were identified. Adjusted between-group differences are presented as estimated mean differences with 95% confidence intervals. Effect sizes are reported as partial eta squared (ηp²), interpreted as small (0.01), moderate (0.06), and large (≥ 0.14).

Given baseline differences in age and BMI, sensitivity analyses were additionally performed by including age and BMI as covariates in adjusted mixed models. These analyses yielded findings consistent with the primary models. Because all randomized participants completed follow-up, all available observations were analyzed according to randomized allocation.

Harms and adverse events

No intervention-related adverse events or unintended effects were reported in this study.

Results

Participant flow and baseline characteristics

Fifty-two IT professionals were screened for eligibility, of whom 30 met the inclusion criteria and were randomized equally to the static stretching group (n = 15) or the myofascial release (MFR) group (n = 15). Twenty-two individuals were excluded because they did not meet the eligibility criteria (n = 11), declined participation (n = 4), or did not provide a reason for non-participation (n = 7). All randomized participants completed the intervention and follow-up assessments, with no losses to follow-up or protocol deviations. Accordingly, all 30 participants were included in the final analyses (Fig. 3).

Fig. 3.

A CONSORT (2010) flow diagram shows the study procedures, including the participants’ enrollment, eligibility assessment, randomization, allocation to intervention group, follow-up, and data analysis

Baseline demographic and clinical characteristics are presented in Table 1. Groups were comparable for primary and secondary outcome measures at baseline, with minimal differences in AKE-ROM and LEFS. Some imbalance was observed in age and body composition variables; therefore, sensitivity analyses adjusting for age and BMI were performed and yielded findings consistent with the primary mixed-model results. To further assess the magnitude of baseline imbalance, standardized mean differences indicated moderate differences for age and BMI; however, adjustment for these variables in sensitivity analyses did not materially alter treatment estimates or statistical conclusions.

Table 1.

Baseline demographic and clinical characteristics of participants

Variables	SS (n = 15)	MFR (n = 15)	Mean differences (95% CI) *
Age (years)	25.13 ± 2.36	27.40 ± 2.35	-2.27 (-4.03 to -0.51)
Height (m)	1.77 ± 0.07	1.77 ± 0.04	0.01 (-0.03 to 0.04)
Weight (kg)	69.64 ± 6.81	76.93 ± 5.17	-7.29 (-11.85 to -2.73)
BMI (kg/m²)	22.44 ± 2.79	24.49 ± 1.83	-2.05 (-3.80 to -0.30)
Baseline AKE-ROM (°)	140.13 ± 7.06	139.80 ± 5.39	0.33 (-4.33 to 4.99)
Baseline LEFS	68.53 ± 3.50	67.73 ± 3.59	0.80 (-1.87 to 3.47)

Values are mean ± standard deviation

*Mean difference calculated as Static Stretching minus Myofascial Release. Positive values favor higher values in the static stretching group

SS Static Stretching, MFR Myofascial Release, AKE-ROM Active knee extension range of motion (degrees), LEFS Lower extremity functional scale score, BMI Body mass index (kg/m²), CI Confidence interval (CI are presented for descriptive comparison and not for formal baseline hypothesis testing)

Short-term effects of interventions

Linear mixed-effects modeling demonstrated significant improvements over time in both active knee extension range of motion (AKE-ROM) and lower extremity function (LEFS) (all time effects p < 0.001).

For AKE-ROM, significant improvements from baseline were observed at Day 8 (+ 4.13°, 95% CI 3.43 to 4.84), Day 15 (+ 8.00°, 95% CI 7.30 to 8.70), and Day 22 (+ 12.27°, 95% CI 11.57 to 12.97).

Similarly, LEFS scores improved significantly over time, with mean increases of 3.40 points (95% CI 2.71 to 4.10) at Day 8, 7.13 points (95% CI 6.44 to 7.83) at Day 15, and 10.13 points (95% CI 9.44 to 10.83) at Day 22.

Interaction effects were observed for both outcomes, although substantially stronger for AKE-ROM than LEFS, indicating a more pronounced differential treatment response for hamstring flexibility than for functional improvement (Table 2).

Table 2.

Fixed effects from linear mixed-effects models for longitudinal changes in hamstring flexibility and lower extremity function

Outcomes	Fixed Effect	F-value	df	p-value	Effect Size (ηp2)
AKE-ROM	Time	184.62	3, 84	< 0.001	0.869
	Group	9.48	1, 28	0.005	0.253
	Group x Time	17.31	3, 84	< 0.001	0.382
LEFS	Time	146.27	3, 84	< 0.001	0.839
	Group	4.29	1, 28	0.048	0.132
	Group x Time	3.89	3, 84	0.012	0.122

Abbreviations: AKE-ROM Active knee extension range of motion, LEFS Lower Extremity Functional Scale, ηp² Partial eta squared (effect size)

Linear mixed-effects models included fixed effects for group, time, and group-by-time interaction with participant-specific random intercepts. Significant interaction effects indicate differential longitudinal response between interventions

Adjusted between-group comparisons

Estimated marginal mean comparisons derived from the linear mixed-effects models showed significantly greater improvements in AKE-ROM in the static stretching group compared with MFR at all follow-up assessments, with the magnitude of difference increasing progressively over time and reaching 5.20° (95% CI 4.21 to 6.19) by Day 22.

For LEFS, between-group differences were comparatively small. Although statistical differences were observed at later assessments, their magnitude remained below reported minimal clinically important differences, suggesting broadly comparable functional benefit between interventions. Adjusted between-group contrasts for both outcomes are presented in Table 3.

Table 3.

Adjusted between-group contrasts from linear mixed-effects models

Outcomes	Time	Mean Difference	95% CI	p-value*
AKE-ROM (0)	Day 8	1.73	0.74–2.73	0.001
	Day 15	3.27	2.28–4.26	0.001
	Day 22	5.20	4.21–6.19	0.001
LEFS	Day 8	0.60	-0.38-1.58	0.231
	Day 15	1.33	0.35–2.32	0.008
	Day 22	1.07	0.08–2.05	0.033

Values represent adjusted estimated marginal mean differences derived from the primary mixed-effects models without covariate adjustment. Sensitivity analyses including age and BMI as covariates yielded consistent findings and did not materially alter treatment estimates

*Statistically significant, if p-value < 0.05

Within-group improvements

Both intervention groups demonstrated significant within-group improvements across assessment intervals (all Bonferroni-adjusted post hoc comparisons p < 0.001). Estimated marginal mean trajectories (Figs. 4 and 5) showed progressive improvement in both groups, with a more pronounced AKE-ROM trajectory favoring static stretching, whereas LEFS trajectories were largely parallel.

Fig. 4.

Estimated marginal mean (± SE) trajectories for active knee extension range of motion (AKE-ROM) across baseline and follow-up assessments in the static stretching and myofascial release groups, derived from linear mixed-effects modeling

Fig. 5.

Estimated marginal mean (± SE) trajectories for Lower Extremity Functional Scale (LEFS) scores across baseline and follow-up assessments in the static stretching and myofascial release groups, derived from linear mixed-effects modeling

Sensitivity analysis

Because significant baseline differences were observed for age and BMI, sensitivity analyses were performed using adjusted linear mixed models including age and BMI as covariates. These analyses yielded findings consistent with the primary models, with persistence of the significant group-by-time interaction for AKE-ROM and no clinically meaningful alteration in LEFS findings.

Harms and adverse events

No intervention-related adverse events, treatment complications, or unintended effects were reported in either group during the study.

Discussion

This randomized controlled trial compared the short-term effects of static stretching and myofascial release (MFR) on hamstring flexibility and lower extremity function in sedentary IT professionals with hamstring tightness. Three principal findings emerged. First, participants in both intervention groups demonstrated significant improvements over time in AKE-ROM and self-reported LEFS scores. Second, static stretching was associated with greater improvements in AKE-ROM than MFR, with the between-group difference increasing progressively throughout the intervention period. Third, despite greater gains in flexibility in the static stretching group, improvements in self-reported lower-extremity function were broadly comparable between interventions.

Because the study did not include a non-intervention or usual-care control group, the observed improvements cannot be attributed exclusively to the interventions themselves. Repeated testing effects, natural temporal variation, participant expectations, and other nonspecific treatment-related factors may also have contributed to the observed changes. Consequently, the findings should be interpreted as associations observed during the intervention period rather than definitive evidence of treatment efficacy.

The greater improvement in hamstring flexibility observed following static stretching is generally consistent with previous literature supporting the effectiveness of stretching interventions for improving muscle flexibility and joint range of motion [14–19]. Static stretching has been proposed to influence flexibility through mechanisms such as increased stretch tolerance, alterations in passive musculotendinous stiffness, viscoelastic adaptation, and neuromuscular modulation [14–19, 31]. However, these mechanisms were not directly examined in the present study and therefore should be considered potential explanations rather than study-derived findings. The progressively increasing between-group differences in AKE-ROM observed over time may be consistent with cumulative adaptations associated with repeated stretching exposure, although the physiological basis of these changes remains uncertain.

The present findings extend existing evidence by demonstrating improvements in flexibility in a sedentary occupational population, a group that has received less attention than athletic or recreationally active cohorts [12–17]. Given the musculoskeletal demands associated with prolonged sitting and reduced movement exposure, interventions targeting flexibility may be particularly relevant to workplace health and occupational rehabilitation programs.

Importantly, although static stretching demonstrated statistically greater improvements in AKE-ROM than MFR, the adjusted between-group difference at Day 22 (5.20°) remained smaller than previously reported minimal detectable change values for the AKE test (approximately 7–8°) [21]. Therefore, while statistical superiority was observed, the clinical importance of this difference remains uncertain. This distinction between statistical significance and clinical relevance is important when interpreting the practical implications of the findings and supports a more cautious interpretation of the comparative advantage of static stretching.

Participants receiving MFR also demonstrated significant improvements in hamstring flexibility over time. Previous randomized trials and systematic reviews have suggested that MFR may improve flexibility through mechanisms that could include altered fascial glide, neuromodulatory responses, and reductions in passive tissue resistance [20–25, 32]. Nevertheless, the precise mechanisms underlying these effects remain incompletely understood, and no mechanistic outcomes were assessed in the present study. Consequently, any mechanistic interpretation should be considered speculative and based on previous literature rather than direct evidence from the current investigation. The smaller gains observed following MFR may therefore reflect differences in therapeutic mechanisms rather than an absence of benefit.

An important observation was that greater flexibility gains following static stretching were not accompanied by clinically superior functional outcomes. Although small statistical differences in self-reported LEFS scores emerged at later follow-up assessments, these differences remained below reported minimal clinically important difference thresholds and were therefore unlikely to represent meaningful functional superiority. Similar discrepancies between biomechanical improvements and patient-reported functional outcomes have been reported in previous rehabilitation studies involving stretching and manual therapy interventions [22, 24, 26].

The similarity in functional outcomes despite differences in flexibility may suggest that self-reported lower extremity function is influenced by factors beyond hamstring flexibility alone. Functional improvements may also reflect changes in movement confidence, symptom perception, neuromuscular control, ergonomic adaptation, or other behavioral factors that were not directly measured in the present study. It is therefore possible that both interventions influenced these factors similarly, resulting in comparable functional trajectories despite differing effects on AKE-ROM.

From a clinical perspective, the findings may be relevant to occupational rehabilitation and workplace health programs targeting sedentary workers. Although the absence of a control group precludes definitive conclusions regarding treatment efficacy, both interventions were associated with improvements in flexibility and self-reported function over the intervention period. Static stretching may be preferable when maximizing hamstring flexibility is the primary clinical objective, whereas either intervention may be considered when the goal is short-term functional improvement. Given their low cost, minimal equipment requirements, and ease of implementation, both approaches may be feasible components of workplace wellness initiatives aimed at addressing musculoskeletal dysfunction associated with prolonged sitting and exposure to sedentary work [8–10, 33].

A methodological strength of this study was the use of linear mixed-effects modeling, which allowed repeated measurements to be analyzed longitudinally while accounting for within-subject dependency. This approach provided robust estimation of treatment trajectories and clinically interpretable adjusted mean differences with corresponding confidence intervals. In addition, sensitivity analyses adjusting for baseline differences in age and BMI yielded findings consistent with the primary analyses, supporting the stability of the observed results.

Despite these strengths, several limitations should be acknowledged. First, the absence of a non-intervention or usual-care control group limits causal interpretation of the observed improvements. Second, although treatment frequency, intervention duration, therapist supervision, and treatment scheduling were standardized, complete equivalence of intervention dosage was not achievable because the intervention structures inherently differed. Participants in the MFR group received more therapist-administered applications per session than those in the static stretching group. Consequently, differences in treatment exposure and therapist contact time may have influenced the observed responses and should be considered when interpreting the comparative findings. Third, significant baseline differences in age, weight, and BMI were observed despite randomization. Although sensitivity analyses adjusting for age and BMI did not materially alter treatment estimates, residual confounding cannot be completely excluded. Fourth, the sample size was relatively small, and participants were recruited from a single geographic region, which may limit generalizability. Fifth, outcomes were evaluated only over a three-week intervention period, precluding conclusions regarding long-term effectiveness and sustainability of treatment effects. Finally, trial registration was performed retrospectively after participant enrollment and data collection had been completed. Although the study protocol, outcome measures, intervention procedures, and planned statistical analyses were established before participant recruitment and remained unchanged throughout the study. Retrospective trial registration represents an additional methodological limitation because prospective verification of study procedures before participant enrollment was not possible.

Future studies should incorporate larger multicenter samples, prospectively registered protocols, longer follow-up periods, and non-intervention control groups to better establish treatment effectiveness and the long-term sustainability of outcomes. Further investigation into the physiological and biomechanical mechanisms underlying improvements in hamstring flexibility and extensibility may also help clarify the differential responses observed between static stretching and myofascial release. In addition, future research should evaluate the integration of these interventions into multimodal workplace health and ergonomic programs, including their potential role alongside posture modification, movement breaks, and occupational health strategies aimed at reducing musculoskeletal dysfunction in sedentary workers.

Conclusions

Both static stretching and myofascial release were associated with improvements in hamstring flexibility and self-reported lower extremity function over the three-week intervention period. Static stretching demonstrated statistically greater improvements in AKE-ROM; however, the magnitude of this difference remained below published minimal detectable change values, and its clinical importance therefore remains uncertain. Functional improvements were broadly comparable between interventions. Given the absence of a control group, the short follow-up period, baseline group imbalances, and retrospective trial registration, the findings should be interpreted cautiously. Further adequately powered, prospectively registered, and controlled trials are required to confirm the comparative effectiveness of these interventions in sedentary occupational populations.

Authors’ contributions

M.A., R.K., P.B., A.K., A.R.K., M.K., A.H.A., and A.I. proposed the study concept and design. M.A., R.K., A.I., and P.B. planned the methodology. M.A., R.K., A.I., and P.B. collected data. A.I., A.H.A., A.R.K., M.K., and A.K. contributed to the data analysis. R.K., P.B., A.H.A., A.S., A.R.K., M.K., and A.I. contributed to the data interpretation. M.A., R.K., P.B., A.R.K., M.K., and A.I. prepared the manuscript’s initial draft. M.A., R.K., P.B., A.K., A.R.K., M.K., A.H.A., and A.I. critically reviewed and edited the manuscript for intellectual content. All authors read and approved the manuscript’s final version to be submitted or published and take responsibility for the intellectual content of the same manuscript.

Funding

This study was funded by the Ongoing Research Funding program, Research Chairs (ORF-RC-2026-10-04), King Saud University, Riyadh, Saudi Arabia. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Data availability

All data generated or analyzed during this study is available from the corresponding author upon a reasonable request.

Declarations

Ethics approval and consent to participate

Ethical approval for the study was obtained from the Ethics Sub-Committee at King Saud University, Riyadh, Saudi Arabia under ethical approval file ID: RRC-2020-04 dated 13-01-2020. The study was completed following the norms and guidelines per Declaration of Helsinki (2010). Furthermore, this study protocol was retrospectively registered in “ClinicalTrial.gov PRS” under a trial identifier NCT06586554 dated 04/09/2024. All participants provided written informed consent before participation in this study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.