Effects of Blood Flow Restriction Training on Clinical Outcomes for Patients With ACL Reconstruction: A Systematic Review.

CONTEXT: Knee muscle atrophy and weakness are common impairments after anterior cruciate ligament (ACL) reconstruction. Blood flow restriction (BFR) training represents a new approach to treat such impairments. However, limited evidence currently exists to support this intervention in related patients. OBJECTIVE: To appraise literature comparing the effects of BFR training with conventional therapy on knee muscle morphological and strength properties in ACL-reconstructed patients. DATA SOURCES: PubMed, SPORTDiscus, CINAHL, and Cochrane Central Register databases were searched for relevant articles from January 1991 through April 2021. STUDY SELECTION: Articles were minimum Level 3 evidence focusing on knee muscle morphologic as well as extensor and flexor strength outcomes in ACL-reconstructed patients of all graft types. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 2. DATA EXTRACTION: Critical appraisal instruments (Downs and Black checklist, Cochrane Collaboration tool, ROBINS-1 tool) were used to evaluate study quality. We independently calculated effect sizes (ESs) (Cohen d) between groups in each study. The Strength of Recommendation Taxonomy grading scale was used for clinical recommendations. RESULTS: Six articles (4 randomized control studies, 1 nonrandomized study, and 1 case-control study) met inclusion criteria. Exercises paired with BFR training included open kinetic chain, closed kinetic chain, and passive applications. Diverse assessments and time of intervention were observed across studies. ESs ranged from trivial to large in favor of BFR training for muscle morphological (d = 0.06 to 0.81) and strength assessments (d = -0.12 to 1.24) with CIs spanning zero. CONCLUSION: At this time, grade B or inconsistent and limited-quality patient-oriented evidence exists to support using BFR training to improve or maintain thigh muscle size as well as knee extensor and flexor strength in ACL-reconstructed patients. ESs indicated no consistent clinically meaningful differences when compared with conventional therapy. Subsequent analyses should be repeated as new evidence emerges to update practice guidelines.

Running mechanics during 1600 meter track runs in young adults with and without chronic ankle instability.

OBJECTIVE: To evaluate biomechanical measures in runners with and without chronic ankle instability (CAI) using wearable sensors during two 1600 m track runs at a slow- and fast-pace. DESIGN: Observational case-control. SETTING: Field. PARTICIPANTS: 18 recreational runners (CAI: n = 9; Healthy: n = 9) with rearfoot strike patterns. MAIN OUTCOME MEASURES: Pronation excursion, maximum pronation velocity, peak braking g, peak impact g, contact time, cycle time, and stride length of every step of two 1600 m runs were collected using RunScribe™ sensors and binned to each 400 m lap (Lap 1 to Lap 4). RESULTS: Significant group-by-lap interactions were identified for contact time (p = .05) during the slow-intensity run. The CAI group had greater contact time (p = 0.05) that progressively increased with distance completed. CAI group also had higher impact g than the control group throughout the slow-intensity run (p = .03). During the fast-intensity run, significant group by lap interaction was observed for pronation excursion with the CAI group exhibiting less pronation excursion than the healthy group as the run progressed (p = .002). CONCLUSIONS: Regardless of speed, runners with CAI demonstrated altered gait mechanics compared to healthy controls. During the higher intensity run, decreased pronation excursion was observed in the CAI group and differences became more prominent as the distance increased.