Brian E. Barnett

Influence of relative blood flow restriction pressure on muscle activation and muscle adaptation.

Introduction: The aim of this study was to investigate the acute and chronic skeletal muscle response to differing levels of blood flow restriction (BFR) pressure. Methods: Fourteen participants completed elbow flexion exercise with pressures from 40% to 90% of arterial occlusion. Pre/post torque measurements and electromyographic (EMG) amplitude of each set were quantified for each condition. This was followed by a separate 8‐week training study of the effect of high (90% arterial occlusion) and low (40% arterial occlusion) pressure on muscle size and function. Results: For the acute study, decreases in torque were similar between pressures [–15.5 (5.9) Nm, P = 0.344]. For amplitude of the first 3 and last 3 reps there was a time effect. After training, increases in muscle size (10%), peak isotonic strength (18%), peak isokinetic torque (180°/s = 23%, 60°/s = 11%), and muscular endurance (62%) changed similarly between pressures. Conclusion: We suggest that higher relative pressures may not be necessary when exercising under BFR. Muscle Nerve 53: 438–445, 2016

Muscle adaptations following 21 consecutive days of strength test familiarization compared with traditional training

Large increases in 1‐repetition maximum (1RM) strength have been demonstrated from repeated testing, but it is unknown whether these increases can be augmented by resistance training.

Blood flow occlusion pressure at rest and immediately after a bout of low load exercise.

The purpose of this study was to determine whether arm circumference is predictive of arterial occlusion in the standing position and to determine the change in pressure before and immediately after exercise. Thirty‐one participants had their arm circumference, blood pressure and standing arterial occlusion determined before exercise. Participants then completed elbow flexions at 40% of resting arterial occlusion at 30% of their one repetition maximum (1RM). The goal repetitions for the exercise included one set of 30 repetitions followed by 3 sets of 15, with 30s rest between sets. Immediately following the last set, postexercise arterial occlusion was determined. Two different models of hierarchical linear regression were used to determine the greatest predictor of standing arterial occlusion. Our final model explained 69% of the variance in arterial occlusion with arm circumference (β = 0·639, part = 0·568) explaining more than brachial systolic blood pressure (β = 0·312, part = 0·277). Standing arterial occlusion increased from pre‐ [138 (15) mmHg] to post‐ [169 (20) mmHg] exercise (P<0·001). In conclusion, the cardiovascular response to blood flow restriction (BFR) in the upper arm following 4 sets of elbow flexion exercise decreases the relative arterial occlusion pressure. In addition, we confirm previous data that circumference explains the most unique variance in arterial occlusion pressure in the upper body. These findings are important as they provide additional insight into making the pressure more uniform between participants throughout exercise.

Muscle adaptation to 21 Straight Days of Elbow Flexor Exercise in Trained Individuals: 1634 Board #287 June 2, 8: 00 AM - 9: 30 AM.

outcome was any injury to the athletes. The secondary outcome was any injury to the upper extremity. Injury occurrence and location in the body, type of injury on upper extremities were recorded. Statistical analyses were done with chi-square test. RESULTS: During the 9-months season, upper extremity injury rates were 14.3% (n=7) and 25.8 % (n=8) in the intervention group and control group, respectively. 70% (n=5) interphalangeal sprain and 30% (n=2) rotator cuff tendinitis were observed in the intervention group. 12 % (n=1) shoulder dislocation, 12 % (n=1) rotator cuff tendinitis and 75% (n=6) interphalangeal sprain were diagnosed in the control group. However, there was no statistically significant difference between groups (p=0.19). CONCLUSION: The findings of this study revealed that the T10 exercise program has no effect in reducing the rates of injuries in adolescent overhead athletes. Further studies with more focus on exercise compatibility and larger sample size are warranted.