Low-Load Blood Flow Restriction Training vs Traditional Resistance Training Exercises Following Anterior Cruciate Ligament Reconstruction Surgery: A Pilot Randomized Controlled Trial
Phase: NA
Conditions: Strength, Range of Motion, Pain-Knee, Skeletal Muscle Hypertrophy, Effusion Joint
Sponsor: Abasyn University Peshawar

Cover letter 
 
Title: Low-Load Blood Flow Restriction Training vs Traditional Resistance Training 
Exercises Following Anterior Cruciate Ligament Reconstruction Surgery: A Pilot 
Randomized Controlled Trial 
NCT ID: NCT06480032 
Date: 01-08-2025 
Document type: Statistical protocol with statistical analysis plan 
Prepared by: Mohammad Shoaib Khan 
Institution: Nazarbayev University 
Contact Information: [+92 3440131307, +7 747 6028215] 
Email: shoaib.khan@nu.edu.kz 
Confidentiality Statement: This document is confidential and intended solely for the 
purpose of clinical study. Unauthorized access, copying, or other distribution of this 
document is strictly prohibited. 
Purpose Statement: This document outlines the study protocol and statistical analysis 
plan for evaluating the effectiveness of low-load blood flow restriction training compared 
with traditional resistance training following anterior cruciate ligament reconstruction 
surgery (ACLR). The purpose is to ensure transparency, and adherence to ethical research 
practices throughout the study. 
Ethical Considerations 
This version of the Study Protocol and Statistical Analysis plan was reviewed and 
approved by the Rehman Medical Institute- Research ethics committee. 
Approval No. RMI/RMI-REC/Approval/209, on 31-May-2024 
 
 
 
 
 
Table of contents 

 
Contents 
Study Protocol and Statistical Analysis Plan ......................................................................................................... 3 
Study Protocol ..................................................................................................................................................... 3 
Background ..................................................................................................................................................... 3 
Objective ..................................................................................................................................................... 3 
1. Study Type ....................................................................................................................................................... 4 
2. Primary Purpose ............................................................................................................................................... 4 
3. Study Phase ...................................................................................................................................................... 4 
4. Intervention Model ........................................................................................................................................... 4 
 
Model Description: ....................................................................................................................................... 4 
 
Single-Assessor Blinded: .............................................................................................................................. 4 
 
Target Sample Size: 32 participants. .............................................................................................................. 5 
9. Ethical Considerations ..................................................................................................................................... 6 
Outcome Measures: .............................................................................................................................................. 6 
 

Study Protocol and Statistical Analysis Plan 
 
    Study Protocol  
 
 
Background 
Anterior cruciate ligament reconstruction (ACLR) is a common surgical procedure for 
athletes and active individuals who suffer ACL tears. Despite successful surgery, 
significant challenges remain during rehabilitation, including persistent quadriceps 
muscle atrophy and strength deficits, which can delay functional recovery and return 
to sport (Ardern et al., 2011). Traditional resistance training is effective for muscle 
hypertrophy but may not be feasible for all patients in the early postoperative phase 
due to load restrictions and joint stress. 
Low-load blood flow restriction (LL-BFR) training has emerged as an innovative 
rehabilitation strategy that combines low-intensity resistance exercise with partial 
vascular occlusion to enhance muscle growth and strength while using much lower 
loads than traditional resistance training (Hughes et al., 2017). Evidence suggests that 
BFR can safely stimulate muscle hypertrophy comparable to high-load training and 
may reduce joint stress, making it particularly suitable for patients recovering from 
ACLR (Scott et al., 2015).This pilot study aims to compare the effectiveness of LL-
BFR and traditional resistance training in improving muscle size, strength, range of 
motion, pain, and joint effusion in patients following ACLR, contributing to the 
evidence base for optimal post-surgical rehabilitation strategies. 
Objective 
The main objective/s of the study is to compare the effectiveness of low load blood 
flow restriction training (LL-BFR) with traditional resistance training exercises (T-
RT) at improving skeletal muscle hypertrophy, strength, Range of motion (ROM), 
pain and effusion in individuals who have undergone anterior cruciate ligament 
(ACL) reconstruction surgery. 
 

Study Design 
1. Study Type 
Interventional: The study (Pilot randomized controlled trial) involves an active 
intervention (BFR-RT vs. T-RT) to evaluate treatment efficacy. 
 
2. Primary Purpose 
Treatment: The study aims to assess the therapeutic effectiveness of BFR-RT compared 
to traditional low load training in improving post-ACLR outcomes. 
 
3. Study Phase 
N/A: The trial does not involve investigational drugs or biologics. 
4. Intervention Model 
Parallel Design: Two distinct groups receive different interventions simultaneously: 
Group 1 (BFR-RT): Low-load resistance training with blood flow restriction along with 
standard rehabilitation. 
Group 2 (T-RT): Low-load traditional resistance training with standard rehabilitation. 
 Model Description: 
BFR-RT group undergoes 8 weeks of BFR training followed by standard rehabilitation 
protocol progression. 
T-RT group receives standard rehabilitation alone for the entire duration. 
 
5. Number of Arms 
2 Arms: 
Experimental Arm: BFR-RT. 
Active Comparator Arm: T-RT. 
6. Masking (Blinding) 
 Single-Assessor Blinded: 
Investigator: The researcher assessing outcomes is blinded to group assignments. 
Participant: Participants are aware of their group (open-label for participants). 

Care Provider: Therapists administering interventions are unblinded. 
None (Open Label): Not applicable; partial blinding is used. 
 
6. Allocation 
Participants are randomly assigned to BFR-RT or T-RT groups. 
Method: Opaque envelopes with coded assignments prepared by an independent team 
member. 
Stratification: Not specified, but typically balanced for age, sex, or baseline function. 
 
7. Enrollment 
 Target Sample Size: 32 participants. 
Type: Actual (confirmed enrolled participants). 
Justification: Based on power analysis to detect clinically significant differences in 
muscle hypertrophy/strength. 
 
8. Additional Protocol Details 
Intervention Protocol 
Frequency: Biweekly sessions (16 total over 8 weeks). 
BFR Technique: 
 Occlusion band placed proximally on the affected limb. 
 Tightness standardized to allow one finger beneath the band. 
Standard Rehabilitation: 
 Includes range of motion (ROM) exercises, strengthening, and functional training 
per hospital protocol. 
Outcome Assessments 
Time Points: Baseline (Week 0-1), Mid-Intervention (Week 4-5), Post-Intervention 
(Week 9). 
Measures: 
Primary: Muscle hypertrophy (ultrasound/MRI), strength (manual muscle testing). 

Secondary: Pain (KOOS), knee ROM, effusion (circumference), adherence rates. 
Safety Monitoring 
 Adverse Events: Documented throughout; none reported in this trial. 
 Exclusion Safeguards: No vascular pathologies or anticoagulant use. 
 
9. Ethical Considerations 
Informed Consent: Obtained from all participants. 
Approval: Ethical approval was taken from the Institutional Review Board (IRB) of 
Rehman Medical Institute. 
 
10. Participants: 
 Inclusion criteria: Individuals who have undergone ACL reconstruction surgery 
within the past 4 weeks, free of any neurological impairments or significant 
cardiac, pulmonary, or metabolic conditions. 
 Exclusion criteria: Individuals with contraindications to exercise, any other 
comorbidity, or systemic inflammatory conditions. 
Outcome Measures: 
 Primary Outcome: Muscle strength (measured using manual muscle technique). 
Muscle size (measured via measuring tap), ROM (Using goniometer), pain (using 
a Visual Analog Scale), and joint effusion (assessed clinically). 

 
This Statistical analysis plan (SAP) compares postoperative rehabilitation outcomes 
between an experimental training group (n=16) and a control group (n=16) across three 
key timepoints: immediate post-surgical baseline (0-1 week), mid-intervention (4-5 
weeks), and post-intervention (8-9 weeks). The study employs a repeated measures 
design to evaluate five primary outcome domains: muscle size (continuous, cm), range of 
motion (continuous, degrees), muscle strength (ordinal, 0-5 scale), pain perception 
(ordinal, VAS 0-10), and joint effusion (ordinal, 0-3 clinical scale). 
In contrast, This SAP includes descriptive statistics, normality assessments, inferential 
statistical tests with corresponding assumptions, multiple comparison adjustments, 
missing data handling procedures, and software implementation to ensure reproducibility. 
 
 
1. Descriptive Statistical Approaches 
Comprehensive descriptive analyses will precede all inferential testing to characterize the 
dataset and inform appropriate test selection. For continuous variables (muscle size, 
ROM), we will report means with standard deviations (SD) for normally distributed data 
and medians with interquartile ranges (IQR) and full ranges for non-normal distributions, 
supplemented by graphical representations including boxplots with superimposed 
individual data points to visualize both group trends and individual trajectories. Ordinal 
variables (strength, pain, effusion) will be summarized using median scores with IQRs 
and frequency distribution tables showing counts/proportions at each ordinal level, with 
stacked bar charts employed to visualize proportional changes across timepoints. These 
descriptive analyses will be stratified by group (experimental vs control) and timepoint to 
enable preliminary assessment of intervention effects and data distributions prior to 
formal hypothesis testing. 
 
 
Statistical Analysis Plan 

2. Data Characteristics and Variable Classification 
The dataset comprises both continuous and ordinal variables requiring distinct analytical 
approaches. Continuous variables including muscle circumference (measured via 
standardized tape measure protocol) and active range of motion (measured via 
goniometry by blinded assessors) will be analyzed for both central tendency and 
variability. Ordinal variables including manual muscle testing scores (Medical Research 
Council 0-5 scale), visual analog pain scores (recorded as integers 0-10), and clinician-
rated effusion scales (0=none, 3=severe) will be analyzed using non-parametric methods 
due to their inherent rank-based properties and expected non-normal distributions. All 
variables will be assessed at three protocol-specified timepoints with identical 
measurement protocols maintained across groups to ensure comparability. 
 
3. Normality and Parametric Assumption Testing 
Formal statistical testing for normality assumptions will be conducted for all continuous 
variables prior to selecting inferential methods. The Shapiro-Wilk test (α=0.05) will be 
applied to residuals from all continuous outcome measures within each group-by-time 
combination, supplemented by visual inspection of Q-Q plots and histograms to detect 
deviations from normality that may not reach statistical significance in small samples. 
Homogeneity of variance between groups will be verified using Levene's test for equality 
of variances when parametric between-group comparisons are planned. For instances 
where normality or homogeneity assumptions are violated (Shapiro-Wilk p≤0.05 or 
Levene's p≤0.05), pre-specified non-parametric alternatives will be implemented as 
detailed in subsequent sections. All assumption testing results will be documented in 
supplementary materials to demonstrate the appropriateness of selected analytical 
methods. 
 
4. Primary Inferential Statistical Methods 
4.1 Within-Group Longitudinal Analyses 
For evaluating changes over time within each experimental arm, distinct approaches will 

be employed based on variable characteristics. Continuous variables meeting normality 
assumptions will be analyzed using repeated measures ANOVA with Greenhouse-
Geisser correction for sphericity violations, followed by paired t-tests with Bonferroni-
adjusted α levels for post-hoc timepoint comparisons when omnibus tests reach 
significance. Non-normal continuous data and all ordinal outcomes will utilize the 
Friedman test (non-parametric equivalent to repeated measures ANOVA) followed by 
Wilcoxon signed-rank tests for post-hoc comparisons with appropriate multiplicity 
adjustments. Effect sizes will be reported as Cohen's d for parametric analyses and rank-
biserial correlations for non-parametric tests to quantify the magnitude of observed 
changes independent of sample size considerations. 
 
4.2 Between-Group Comparative Analyses 
Experimental versus control group comparisons at each timepoint will employ 
independent samples t-tests for normally distributed continuous variables with equal 
variances, Welch's t-tests for unequal variances (as determined by Levene's test), and 
Mann-Whitney U tests for non-normal continuous or ordinal data. Between-group effect 
sizes will be reported as mean differences with 95% confidence intervals for parametric 
tests and Hodges-Lehmann median differences for non-parametric analyses. To account 
for baseline imbalances in this pilot study, exploratory analyses of covariance 
(ANCOVA) may be conducted for continuous outcomes using baseline measurements as 
covariates if substantial pre-intervention group differences are detected despite 
randomization. 
 
5. Missing Data Handling Protocol 
Missing data patterns will be formally evaluated using Little's MCAR test prior to 
primary analyses. Given the pilot nature of this study with limited sample size, primary 
analyses will employ complete case approaches with explicit reporting of missing data 
proportions by group and timepoint. Sensitivity analyses will compare complete case 
results with multiple imputation approaches using chained equations (MICE) 

incorporating baseline characteristics and observed follow-up data as predictors. 
Participants with missing baseline data will be excluded from all analyses, while those 
missing later timepoints will be retained for analyses where their available data permits. 
A participant flow diagram will document attrition at each study phase. 
 
6. Software Implementation and Reproducibility 
All analyses will be conducted using Stata MP 18.0. Graphical outputs will adhere to 
STROND guidelines for transparent reporting of non-normal data distributions. 
 
 
 

 
Reference:  
Ardern, C. L., Webster, K. E., Taylor, N. F., & Feller, J. A. (2011). Return to sport 
following anterior cruciate ligament reconstruction surgery: A systematic review 
and meta-analysis of the state of play. British Journal of Sports Medicine, 45(7), 
596–606. https://doi.org/10.1136/bjsm.2010.076364 
Hughes, L., Paton, B., Rosenblatt, B., Gissane, C., & Patterson, S. D. (2017). Blood flow 
restriction training in clinical musculoskeletal rehabilitation: A systematic review 
and meta-analysis. British Journal of Sports Medicine, 51(13), 1003–1011. 
https://doi.org/10.1136/bjsports-2016-097071 
Scott, B. R., Loenneke, J. P., Slattery, K. M., & Dascombe, B. J. (2015). Exercise with 
Blood Flow Restriction: An Updated Evidence-Based Approach for Enhanced 
Muscular Development. Sports Medicine, 45(3), 313–325. 
https://doi.org/10.1007/s40279-014-0288-1