Comparative Effects of Blood Flow Restriction and Traditional Strength Training on Proximal Shoulder Musculature: A Randomized Clinical Trial
Phase: NA
Conditions: Resistance Training, Blood Flow Restriction (BFR) Training Effects
Sponsor: Alice Maria da Costa Carvalhais

 
 
 
 
 
 
 
 
Comparative Effects of Blood Flow Restriction and Traditional 
Strength Training on Proximal Shoulder Musculature: A Randomized 
Clinical Trial 
 
 
 
Approved by the ethics committee of Instituto Politécnico de Saúde do Norte 
(31/CE-IPSN/2024). 
 
 
 
 
 
 
April 2024 
 
 
 
 
 
 
 
 

STUDY OBJECTIVES 
This study compared a 4-week blood-flow–restriction (BFR) resistance-training 
program performed at 30% of one-repetition maximum (1RM) with traditional 
high-load strength training at 70% of 1RM on shoulder muscle strength, power, 
endurance, and hypertrophy in healthy adults. 
 
 
STUDY DESIGN 
Parallel-group randomized controlled trial with two intervention arms: an 
experimental BFR group (n = 12; 3 men, 9 women) and an active comparator 
high-load group (n = 11; 3 men, 8 women; one dropout). All participants provided 
written informed consent in accordance with the Declaration of Helsinki. 
 
 
PARTICIPANTS AND RECRUITMENT 
Healthy volunteers were recruited via social media, discussion groups, and 
physical postings at CESPU facilities. Individuals of both sexes were eligible 
because prior work indicates comparable metabolic responses to BFR across 
genders. Eligibility was screened using an online questionnaire covering 
demographics, sport participation, and medical history. Eligible respondents were 
contacted by email to schedule baseline testing. 
 
Eligibility Criteria 
Inclusion criteria 
- 
Age 18–40 years 
- 
Body mass index (BMI) 18.5–30 kg/m² (individuals with obesity are 
commonly excluded due to higher cardiovascular, respiratory, and 
rheumatologic risk) 
 
Exclusion criteria 
- 
Participation in sports that heavily use the dominant arm (e.g., tennis, 
volleyball, handball) 
- 
Current upper-limb strength training 
- 
History of trauma or surgery involving the dominant upper limb 

- 
Acute or chronic shoulder pain or radiating pain 
- 
Cervical disc herniation or prior cervical surgery 
- 
Upper-limb edema 
- 
History of deep-vein thrombosis or oncologic/metabolic disease 
- 
Pregnancy 
- 
Persistent symptoms during training: numbness, tingling, or pain >7/10 on 
a numeric rating scale (BFR group criterion) 
- 
Missing more than one training session 
 
Randomization was performed with Sealed Envelope™. 
 
 
METHODS 
Before data collection, the research team completed a familiarization phase to 
standardize equipment use, test administration, training procedures, and safety 
protocols. Responsibilities were assigned to specific team members, and minor 
adjustments were implemented as needed to ensure consistency and 
measurement accuracy. 
 
Outcome assessments were performed after a standardized warm-up and always 
in the same sequence: Arm Circumference, Single-Arm Seated Shot-Put Test, 
Vertical Lift Strength, and Shoulder Endurance Test. Measurements were 
obtained at baseline (M0) and at least 24 h after the final training session (M1). 
Participants were instructed to avoid strenuous upper-limb activity for 24 h before 
testing. 
 
Data-Collection Procedures 
 
Arm Circumference: Circumference at the axillary level of the dominant arm was 
used as a proxy for deltoid muscle mass. With the participant at rest, three 
measurements were taken using a standard tape; the mean value was analyzed. 
 
 

Single-Arm Seated Shot-Put Test (SASSPT): To assess shoulder power and 
upper-limb function, participants sat with trunk and shoulders against a wall, lower 
limbs extended, and the non-tested arm resting on the ipsilateral thigh to minimize 
compensation. Using a 4-kg medicine ball, participants performed maximal 
throws. Distances were recorded using floor tape; throws were video recorded to 
confirm first contact points. Three trials were performed; the mean distance was 
analyzed. 
 
Vertical Lift Strength. Isometric strength for a vertical-lift task was measured with 
the Smart Groin Trainer (NeuroExcellence, Braga, Portugal). Participants were 
seated with the shoulder at 60° abduction and the elbow flexed; force was applied 
in the direction of vertical arm elevation. Three trials were performed; the best 
value was analyzed. 
 
Shoulder Endurance. The Shoulder Endurance Test (SET) was used for its 
controlled cadence. Participants stood with their back against a wall, the 
contralateral heel touching the wall, and the ipsilateral leg positioned forward. The 
movement consisted of shoulder abduction to 90° with external rotation to 90° 
while touching the wall. Resistance was provided by a red elastic band; the hand-
to-anchor distance was fixed at 1 m. A metronome guided cadence, starting at 60 
bpm and increasing by 30 bpm every 20 s up to 150 bpm. The test ended when 
cadence or movement quality could not be maintained. Time to termination 
(seconds) was recorded. 
 
 
Training Protocol 
 
The intervention lasted 4 weeks with two sessions per week. Each session began 
with a warm-up including shoulder and upper-limb mobility and stretching. During 
the first session, 1RM for each exercise was estimated using a repetition-to-
failure approach with appropriate coefficients. 
 
 
 

Three shoulder-focused exercises were prescribed: 
- 
Standing shoulder abduction to 90°, then return to start. 
 
- 
Seated dumbbell overhead press with back support (from shoulder level 
to full overhead and return). 
 
- 
External rotation performed lying on a bench with the upper arm against 
the torso and the elbow flexed at 90°. 
 
High-load strength training group: Training followed ACSM hypertrophy 
guidelines at 70% 1RM. For each exercise, participants completed four sets of 
8–10 repetitions with 2-min rests between sets and exercises. Tempo was 
moderate (1 s concentric, 2 s eccentric). 
 
Low-load strength training with BFR group: Exercises were performed at 30% 
1RM. Each exercise totaled 75 repetitions across four sets (30/15/15/15) with 30-
s inter set rests. Tempo was 2 s concentric and 2 s eccentric. 
 
BFR Application 
BFR was delivered using SmartCuffs® 3.0 PRO (Smart Tools Plus). At each 
session start, the device determined arterial occlusion pressure, and cuffs were 
set to 50% limb occlusion pressure. With participants seated, a 7-cm cuff was 
placed directly on the skin (or over a thin T-shirt) at the most proximal portion of 
the dominant arm (just distal to the deltoid insertion). Pressure was maintained 
during each exercise, released for 60 s between exercises, and reapplied for the 
next exercise. Participants rated pain, tingling, and numbness on a 0–10 numeric 
rating scale; symptoms >7/10 prompted protocol adjustment or session 
cancellation. 
 
Each training session lasted approximately 45 minutes in both groups. 
Participants were asked to maintain their usual physical-activity levels throughout 
the study. 
 
 

STATISTICAL ANALYSIS 
Analyses were performed in SPSS version 29.0 (SPSS Inc., Chicago, IL, USA). 
Quantitative variables are presented as mean ± SD or median (interquartile 
range), as appropriate. Between-group comparisons used Fisher’s exact test, the 
Mann–Whitney U test, or independent-samples t tests. Within-group pre- to post-
changes were evaluated with paired-samples t tests. For significant outcomes, 
Cohen’s d was calculated and interpreted as: very small, 0.01 < d ≤ 0.20; small, 
0.20 < d ≤ 0.50; moderate, 0.50 < d ≤ 0.80; large, 0.80 < d ≤ 1.20; very large, 1.20 
< d ≤ 2.00; and huge, d > 2.00. Statistical significance was set at p < 0.05.