Blood Flow Restriction during Walking Does Not Impact Body Composition or Performance Measures in Highly Trained Runners.

Blood flow restriction (BFR) is a commonly used training modality that has been demonstrated to enhance muscle characteristics such as size and function. The purpose of this study was to determine if a 4-week walking program with or without BFR in healthy, active adults has an effect on body composition, anaerobic, and aerobic running performance. Thirty-three participants, randomized among three groups, completed the walking program, which included five sets of 2 min walking intervals with 1 min rest, with or without BFR, or 10 min walking with BFR. Assessments completed before and after the walking program included body composition, 40-yard sprints, and a VO2MAX test on a treadmill. A two-way ANOVA revealed no changes among the groups nor for any variables at any time (p > 0.05). Additionally, one main effect for time indicated the VO2 at V-slope threshold was greater following training for all groups combined (p = 0.001). The results demonstrate that low volume and intensity walking with BFR for 4 weeks did not provide a sufficient stimulus for changing body composition or performance metrics in a group of very active adults. Longer or more isolated exposure of BFR on the limbs may contribute to more pronounced adaptations.

A Brief Review of the Literature for Published Dual-Energy X-Ray Absorptiometry Protocols for Athletes.

CONTEXT: Dual-energy x-ray absorptiometry (DXA) is widely known for its utility in diagnosing a patient with osteopenia or osteoporosis; however, its utility in evaluation of body composition and potential athletic performance was previously routinely overlooked. In recent years, athletic programs have begun employing this equipment during athlete screening. However, it is currently unknown how athletic programs are utilizing this information to guide an athlete's training and health. OBJECTIVE: To explore the literature to identify what is known regarding sports performance and athlete health based on body composition recordings. DATA SOURCES: PubMed and Google Scholar databases were searched for this brief review. STUDY SELECTION: A focus was placed on articles within the past 10 years that discussed DXA protocols within athletic populations; 14 articles were included in this brief literature review. STUDY DESIGN: Brief literature review. LEVEL OF EVIDENCE: Level 5. DATA EXTRACTION: One member of the research team searched the literature and retrieved articles with the purpose of analyzing and/or explaining DXA imaging in body composition analysis of active persons (primarily athletes). RESULTS: Quality assurance scans with a phantom calibration block as well as athlete prescreening condition and activity standardization was routinely recommended. However, only 1 study reported a specific DXA protocol for athletes, and only 1 study described guidelines for how to report DXA results in athletic populations, suggesting it is plausible yet difficult due to the small changes detectable. CONCLUSION: Due to the limited literature as well as a lack of reference values for specific athletic populations, the authors of this review recommend using the current Nana et al (Int J Sport Nutr Exerc Metab 2015;25:198-215) DXA protocol for performing DXA scans in the athletic population as well as current Hind et al (J Clin Densitom 2018;21:429-443) guidelines for distributing the information.

The Concept of Sport Sampling Versus Sport Specialization: Preventing Youth Athlete Injury: A Systematic Review and Meta-analysis.

BACKGROUND: The prevalence of youth athletes specializing in 1 sport has been increasing over the past decade. Subsequently, the rate of youth athlete injury has also been increasing. It is possible that an association exists between youth specialization and sports injury rate. PURPOSE: To determine if sport sampling is associated with a lower sports injury rate in youths compared with youths who specialize in 1 sport. STUDY DESIGN: Systematic review and meta-analysis. METHODS: A systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using PubMed, Embase, and the Cochrane library. Inclusion criteria included studies written in the English language, studies with athletes between 7 and 18 years of age, studies that report injury rates, and studies that specify if athletes were sport samplers or specialized in a sport. Data relevant to this study, including injuries and patient characteristics, were extracted and statistically analyzed. RESULTS: The initial search identified 324 studies, 6 of which met inclusion criteria. From these 6 studies, the total participant number was 5736. Of those, 2451 (42.7%) were "sport samplers," 1628 (28.4%) were "sport specializers," and 1657 (28.9%) were considered "others" (ie, could not be classified as true samplers or true specializers). The average age of all the athletes was 14.6 years (range, 7-18 years). Sport specializers had a significantly higher injury risk than the sport samplers (RR, 1.37; 95% CI, 1.19-1.57; P < .0001). There was a higher risk of injury in the "others" group when compared with the "sport sampler" group (RR, 1.21; 95% CI, 1.14-1.29; P < .0001). There was a higher risk of injury in the "sport specializer" group over the "others" group (RR, 1.09; 95% CI, 1.04-1.14; P < .005). CONCLUSION: Sport sampling is associated with a decreased risk of sports injury in youth athletes when compared with those who specialize in 1 sport. Injury rates increase as a youth athlete becomes increasingly specialized. Youth athletes would benefit substantially from participating in sport sampling.

Blood Flow Restriction Therapy: Where We Are and Where We Are Going.

Blood flow restriction therapy (BFRT) is an innovative training method for the development of muscle strength and hypertrophy in the athletic and clinical settings. Through the combination of venous occlusion and low-load resistance training, it induces muscle development through a number of proposed mechanisms including anaerobic metabolism, cellular swelling, and induction of type 2 muscle fibers. Muscle weakness and atrophy are prevalent among musculoskeletal rehabilitation patients, causing delayed return to functional activity. In traditional resistance training, muscle development requires exercise loads of 70% of one-repetition maximum (1RM), but the stress placed on connective tissues and joints can be detrimental to the elderly and rehabilitation patients. However, BFRT with loads of 20% to 40% of 1RM has been shown consistently in the literature to increase muscle strength, hypertrophy, and angiogenesis. The rate of adverse effects has not been found to be greater than that in traditional high-load resistance training, but its effects on the cardiovascular system have yet to be evaluated in long-term studies. Although further investigations are needed to determine the exact mechanism and optimal usage, current evidence is promising for the application of BFRT in athletes, rehabilitation patients, and the elderly patients.