The aim of this study is to determine if BFR-LIX promotes greater increases in shoulder lean mass, rotator cuff strength, endurance, and acute increases in shoulder muscle activation compared to LIX alone.
Healthy Volunteers: Thirty-two healthy adults were randomized into two groups (BFRm=13,f=3, NoBFRm=10,f=6) that performed 8wks of shoulder LIX \[2/wk, 4 sets (30/15/15/fatigue), 20%max\] using common rotator cuff exercises \[cable external rotation (ER), cable internal rotation (IR), dumbbell scaption (SCAP), and side-lying dumbbell ER (SLER)\]. The BFR group also trained with an automated tourniquet placed at the proximal arm (50%-occlusion). Regional lean mass (dual-energy-xray-absorptiometry), isometric strength, and muscular endurance (repetitions-to-fatigue, RTF, 20%max, with and without 50%-occlusion) was measured before and after training. Electromyographic amplitude (EMGa) was also recorded from target shoulder muscles during endurance testing. A mixed-model ANCOVA (covaried on baseline measures) was used to detect within and between-group differences in primary outcome measures (α=0.05). Pitchers: Twenty-eight collegiate baseball pitchers were randomized into 2 groups (BFRN=15, NOBFRN=13) that, in conjunction with offseason training, performed 8wks of shoulder LIX \[Throwing arm only; 2/wk, 4 sets (30/15/15/fatigue), 20%isometric max\] using 4 exercises \[cable external and internal rotation (ER/IR), dumbbell scaption, and side-lying dumbbell ER\]. The BFR group also trained with an automated tourniquet on the proximal arm (50%-occlusion). Regional lean mass (dual-energy x-ray absorptiometry), rotator cuff strength (dynamometry: IR0\&90, ° ER0\&90, ° Scaption, Flexion), and fastball biomechanics were assessed pre- and post-training. Achievable workload (sets × reps × resistance) was also recorded. An ANCOVA (covaried on baseline measures) repeated on training timepoint was used to detect within-group and between-group differences in outcome measures (α=0.05). For significant pairwise comparisons, effect size (ES) was calculated using a Cohen's d statistic and interpreted as: 0-0.1, negligible(N); 0.1-0.3, small(S); 0.3-0.5, moderate(M); 0.5-0.7, large(L); \>0.7, very large(VL).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
69
The study group underwent the same exercises as the control group modified by the use of a tourniquet for blood flow restriction during those exercises.
Houston Methodist Hospital
Houston, Texas, United States
Determine if BFR Changes UE Lean Muscle Mass in the General Population
UE lean muscle mass was measured in grams using DEXA. These data are reported as an average of both the left and right side.
Time frame: Baseline and 8 weeks
Isometric Rotator Cuff Strength in General Population
Peak strength was measured using a hand-held dynamometer. A standardized procedure was used for shoulder strength testing, and all testing was performed by a sports-specialized (American Board of Physical Therapy Specialties Sports Clinical Specialist) physical therapist. A total of 6 different maximal isometric strength tests were used to measure the strength of the rotator cuff muscles in the following order: (1) seated forward flexion at 90 of shoulder abduction, (2) seated scaption at 90, (3) seated external rotation (ER) at 0, (4) seated internal rotation (IR) at 0, (5) prone ER at 90, and (6) prone IR at 90. Peak strength was measured using a microFET2 (Hoggan Scientific) hand-held dynamometer. For each isometric test, participants performed a 3-second maximal-exertion contraction against the dynamometer to determine peak strength. For each measure, tests were performed 3 times, and the highest value among the 3 trials was selected as the maximal strength value.
Time frame: Baseline and 8 weeks
Determine if BFR Changes Shoulder Lean Muscle Mass in Pitchers
Shoulder lean muscle mass was measured in grams using DEXA. These data are reported for each arm.
Time frame: Baseline, 8 weeks
Isometric Rotator Cuff Strength in Pitchers
Peak strength was measured using a hand-held dynamometer. A standardized procedure was used for shoulder strength testing, and all testing was performed by a sports-specialized (American Board of Physical Therapy Specialties Sports Clinical Specialist) physical therapist. A total of 6 different maximal isometric strength tests were used to measure the strength of the rotator cuff muscles in the following order: (1) seated forward flexion at 90 of shoulder abduction, (2) seated scaption at 90, (3) seated external rotation (ER) at 0, (4) seated internal rotation (IR) at 0, (5) prone ER at 90, and (6) prone IR at 90. Peak strength was measured using a microFET2 (Hoggan Scientific) hand-held dynamometer. For each isometric test, participants performed a 3-second maximal-exertion contraction against the dynamometer to determine peak strength. For each measure, tests were performed 3 times, and the highest value among the 3 trials was selected as the maximal strength value.
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Time frame: Baseline, 8 weeks
Strength Endurance in General Population
repetitions to fatigue (RTF) were performed for 3 exercises. Volume (repetitions x resistance, kg) was calculated for each trial as is common for strength training investigations. After strength testing, participants were asked to perform the first of 2 endurance tests separated by 48 to 72 hours. On both occasions, a single set of repetitions to fatigue (RTF) were performed for 3 exercises in the following order: standing cable ER at 0 of shoulder abduction, standing cable IR at 0, and dumbbell scaption with each exercise separated by a 2-minute rest period and alternating between arms (order randomized). This test was performed in both groups with and without 50% limb occlusion pressure (LOP) applied by an automated tourniquet system. A nylon cuff was placed around the most proximal portion of the upper extremity for all testing. The order of testing was randomized between the 2 testing days for each participant.
Time frame: Baseline and 8 weeks