Introduction After anterior cruciate ligament reconstruction surgery, returning the knee to previous levels of strength and function is challenging, with the failure to do so associated with an increased risk of reinjury and long-term degenerative problems. Blood flow restriction (BFR) is gaining popularity as a rehabilitation technique; however, its effects on the mechanics of these exercises have not been fully explored. In this study, we aimed to determine the acute effects of BFR on the performance of a step-up exercise protocol and to assess the acceptability of the technique. Methods Twenty individuals (12 female/8 male; mean age, 30.6 yr) who had recently undergone anterior cruciate ligament reconstruction and 20 controls (11 female/9 male, mean age 28.0 yr) performed a step-up exercise protocol with and without BFR. Lower limb kinematics and kinetics were measured and compared between groups and conditions. Testing was completed in June 2019. Results Participants in both groups had increased external rotation of the tibia of 2° (P < 0.001) and reductions in knee flexion and rotation torques around the joint of around 50% (P < 0.001) when using BFR compared with nonrestricted step-up exercise. The intervention was found to increase the difficulty of the exercise and induce moderate levels of discomfort (P < 0.001). Conclusion The present study provides cautious support for the use of BFR, showing that there are minimal changes in knee joint mechanics when performing the same exercise without BFR, and that the changes do not increase joint torques at the knee. From an acute biomechanical perspective, the intervention appears safe to use under qualified supervision; however, effects of repetitive use and long-term outcomes should be monitored.
Background Ultimate Frisbee is a rapidly growing sport played in all levels of competition in men’s, women’s, and coed divisions. Despite widespread popularity, there remains a lack of research on injury risk and prevalence during a season. Purpose To determine the prevalence of injuries among elite club-level men and women Ultimate Frisbee players and to identify elements associated with injury during a single season. Study Design Descriptive epidemiological study. Methods Voluntary preseason and postseason online surveys were distributed to local elite club-level Ultimate teams in 2019. Surveys assessed players’ lifetime Ultimate-associated injury history, injury status, training regimen, and other related elements. Results Fifty-seven and 84 players were eligible to complete the preseason and postseason surveys, respectively. Prior to the 2019 season, 97% of female respondents and 100% of male respondents reported a previous Ultimate-related injury in their career, with all reporting a prior lower extremity injury. During the 2019 season, 56% of respondents reported being injured, and 12% missed one month or more of the season, with 88% of injured players reporting a lower extremity injury. Men reported more ankle and calf injuries than women, and there was a strong negative correlation between time missed due to injury during the 2018 season and the number of days per week spent weight-training and accumulated training. Conclusion There is a high prevalence of lower extremity injury among elite club-level Ultimate players during a single season and pervasive lower extremity injury history may contribute to high injury prevalence. Observed injury patterns suggest targeted interventions including Nordic Hamstring Exercises and balance and proprioceptive training may decrease injury risk. Further research into this topic is needed to help reduce injury in these athletes. Levels of Evidence Level 3.
Objectives:Hamstring injuries are among the most common injuries in sports involving sprinting and have a high recurrence rate (20-33% recurrence rates reported in the literature). Rehabilitation protocols that can prevent recurrences are needed. The purpose of this study was to determine if a protocol emphasizing eccentric strength training with the hamstrings in a stretched position resulted in a low recurrence rate after return to play. Methods: Forty-eight athletes (age 35±16 yr; 31 men, 17 women) with unilateral hamstring strains (3 G1, 41 G2, 4 G3; 27 recurrent injuries) followed a 3-phase rehabilitation protocol (phase 1: isometric and isotonic strengthening at short to intermediate muscle lengths; phase 2: eccentric strengthening at short to intermediate lengths; phase 3: eccentric strengthening in a stretched position). Athletes progressed to the next phase when pain free with maximum contractions and were discharged to sports when pain free with maximal eccentric contractions in a stretched position and with functional tests. Prior to discharge, isometric strength was assessed bilaterally at 80º, 60º, 40º and 20º knee flexion in sitting with the thigh flexed to 40º above horizontal. Eight athletes chose to return to play prior to completing the rehabilitation and were categorized as noncompliant (5 completed phase 2, 3 completed phase 1). Reinjury rates and hamstring strength were compared between compliant and noncompliant athletes using Fisher exact tests and analysis of variance. Results: None of the 40 compliant athletes had sustained a reinjury at an average of 20±13 months after returning to sports (18>2yr, 7 1-2yr, 15<1yr). Three of the 8 noncompliant athletes sustained reinjuries between 3 and 5 months after return to play (P<0.01 vs. compliant athletes). At time of return to sport, noncompliant athletes had significant hamstring weakness, which was progressively worse at longer muscle lengths (20% deficit at 80º, 23% at 60º, 31% at 40º, 43% at 20º; Angle effect P<0.001). Compliant athletes had symmetrical strength at all angles (P=0.99). Compliant athletes averaged 17±7 treatments over 11±7 wks versus 12±7 treatments over 13±11 wks for noncompliant athletes (P=0.11, P=0.53). Conclusion:Rehabilitation with an emphasis on eccentric strength training with the hamstrings in a stretched position resulted in zero recurrent injuries at an average of 1.7 years after return to play.
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