Blood Flow Restriction Therapy Preserves Lower Extremity Bone and Muscle Mass After ACL Reconstruction.

BACKGROUND: Muscle atrophy is common after an injury to the knee and anterior cruciate ligament reconstruction (ACLR). Blood flow restriction therapy (BFR) combined with low-load resistance exercise may help mitigate muscle loss and improve the overall condition of the lower extremity (LE). PURPOSE: To determine whether BFR decreases the loss of LE lean mass (LM), bone mass, and bone mineral density (BMD) while improving function compared with standard rehabilitation after ACLR. STUDY DESIGN: Randomized controlled clinical trial. METHODS: A total of 32 patients undergoing ACLR with bone-patellar tendon-bone autograft were randomized into 2 groups (CONTROL: N = 15 [male = 7, female = 8; age = 24.1 ± 7.2 years; body mass index [BMI] = 26.9 ± 5.3 kg/m2] and BFR: N = 17 [male = 12, female = 5; age = 28.1 ± 7.4 years; BMI = 25.2 ± 2.8 kg/m2]) and performed 12 weeks of postsurgery rehabilitation with an average follow-up of 2.3 ± 1.0 years. Both groups performed the same rehabilitation protocol. During select exercises, the BFR group exercised under 80% arterial occlusion of the postoperative limb (Delfi tourniquet system). BMD, bone mass, and LM were measured using DEXA (iDXA, GE) at presurgery, week 6, and week 12 of rehabilitation. Functional measures were recorded at week 8 and week 12. Return to sport (RTS) was defined as the timepoint at which ACLR-specific objective functional testing was passed at physical therapy. A group-by-time analysis of covariance followed by a Tukey's post hoc test were used to detect within- and between-group changes. Type I error; α = 0.05. RESULTS: Compared with presurgery, only the CONTROL group experienced decreases in LE-LM at week 6 (-0.61 ± 0.19 kg, -6.64 ± 1.86%; P < 0.01) and week 12 (-0.39 ± 0.15 kg, -4.67 ± 1.58%; P = 0.01) of rehabilitation. LE bone mass was decreased only in the CONTROL group at week 6 (-12.87 ± 3.02 g, -2.11 ± 0.47%; P < 0.01) and week 12 (-16.95 ± 4.32 g,-2.58 ± 0.64%; P < 0.01). Overall, loss of site-specific BMD was greater in the CONTROL group (P < 0.05). Only the CONTROL group experienced reductions in proximal tibia (-8.00 ± 1.10%; P < 0.01) and proximal fibula (-15.0±2.50%,P < 0.01) at week 12 compared with presurgery measures. There were no complications. Functional measures were similar between groups. RTS time was reduced in the BFR group (6.4 ± 0.3 months) compared with the CONTROL group (8.3 ± 0.5 months; P = 0.01). CONCLUSION: After ACLR, BFR may decrease muscle and bone loss for up to 12 weeks postoperatively and may improve time to RTS with functional outcomes comparable with those of standard rehabilitation.

Sex-related Anthropometrics in a Lower-Body Mobility Assessment Among Professional Soccer Athletes.

Background: The functional movement screen (FMS™) and Y-balance test (YBT) are commonly used to evaluate mobility in athletes. Purpose: The primary aim of this investigation was to determine the relationship between demographic and anthropometric factors such as sex, body composition, and skeletal dimension and scoring on YBT and FMS™ in male and female professional soccer athletes. Study Design: Cross Sectional. Methods: During pre-season assessments, athletes from two professional soccer clubs were recruited and underwent body composition and skeletal dimension analysis via dual-energy X-ray absorptiometry (DEXA) scans. Balance and mobility were assessed using the YBT and FMS™. A two-tailed t-test was used to compare YBT between sexes. Chi-square was used for sex comparisons of FMS™ scores. Correlation analysis was used to determine if body composition and/or skeletal dimensions correlated with YBT or FMS™ measures. Type-I error; α=0.05. Results: 40 Participants were successfully recruited: (24 males: 27±5yr, 79±9kg; |16 females: 25±3yr, 63±4kg). YBT: Correlations were found between anterior reach and height (r=-0.36), total lean mass (LM)(r=-0.39), and trunk LM(r=-0.39) as well as between posterolateral reach and pelvic width (PW)(r=0.42), femur length (r=0.44), and tibia length (r=0.51)(all p<0.05). FMS™: The deep squat score was correlated with height(r=-0.40), PW(r=0.40), LM(r=-0.43), and trunk LM (r =-0.40)(p<0.05). Inline lunge scores were correlated with height(r=-0.63), PW(r=0.60), LM(r=-0.77), trunk LM(r=-0.73), and leg LM(r=0.70)(all p<0.05). Straight leg raise scores were correlated with PW (r=0.45, p<0.05). Females scored higher for the three lower body FMS™ measures where correlations were observed (p<0.05). Conclusions: Lower body FMS™ scores differ between male and female professional soccer athletes and are related to anthropometric factors that may influence screening and outcomes for the FMS™ and YBT, respectively. Thus, these anatomical factors likely need to be taken into account when assessing baseline performance and risk of injury to improve screening efficacy. Level of Evidence: Level 3b.

Sex-Related Hip Strength Measures Among Professional Soccer Players.

ABSTRACT: Hedt, CA, Pearson, JM, Lambert, BS, McCulloch, PC, and Harris, JD. Sex-related hip strength measures among professional soccer players. J Strength Cond Res 35(7): 1992-1999, 2021-Lower-extremity musculoskeletal injuries in soccer are common among sexes. However, it remains unknown whether differences between sexes exist with regard to absolute or relative hip strength and how these differences may relate to injury. In the current study, we performed a retrospective cross-sectional analysis of pre-season data from male (♂n = 21) and female (♀n = 19) professional United States soccer organizations. Two years of pre-season data were collected for peak strength of lower extremity and hip musculature (no duplicates used). A 2 × 2 multivariate analysis of variance was used to detect differences in hip strength between sexes and dominant compared with nondominant legs. For all significant multivariate effects indicated by Wilks lambda and follow-up univariate analysis, a Tukey's post hoc test was used for pairwise univariate comparisons. A 2-tailed independent-samples T-test was used for comparison of height, body mass, body mass index (BMI), mean leg length, and strength ratios between dominant and nondominant limbs between sexes. Type I error was set at α = 0.05 for all analyses. Height (♂183.1 ± 6.8 cm, ♀170.0 ± 5.5 cm), body mass (♂79.0 ± 8.7 kg, ♀65.1 ± 5.6 kg), BMI (♂23.5 ± 1.3 kg·m-2, ♀22.5 ± 1.4 kg·m-2), and mean leg length (♂95.5 ± 4.34 cm, ♀ 88.3 ± 3.24 cm) differed between groups (p < 0.05). Sex differences (p < 0.05) were also found for hip abduction (dominant ♂19.5 ± 3.6 kg, ♀17.3 ± 2.2 kg; nondominant ♂18.5 ± 3.7 kg, ♀16.0 ± 2.3 kg), adduction (dominant ♂19.8 ± 3.0 kg, ♀16.7 ± 2.3 kg; nondominant ♂20.1 ± 2.9 kg, ♀17.6 ± 2.9 kg), external rotation (dominant ♂21.7 ± 3.4 kg, ♀17.7 ± 2.4 kg; nondominant ♂21.6 ± 3.9 kg, ♀16.8 ± 2.1 kg), and dominant hamstring strength (♂27.9 ± 6.5 kg, ♀23.0 ± 4.9 kg). The ratio of hip internal to external rotation strength differed in the nondominant leg (♂1.1 ± 0.2, ♀0.9 ± 0.2, p < 0.05). No significant differences were found between males and females when measures were normalized to body mass. These findings provide baseline pre-season normative data for professional soccer athletes and indicate that strength differences can be expected among different sexes, but are attenuated with attention to body mass. Further research should indicate how pre-season strength measures relate to injury.

The Utilization of Interval Throwing Programs in the Physical Therapy Setting: A Cross-Sectional Survey.

Context: Interval throwing programs (ITPs) have long been used in the physical therapy setting to aid in the safe and efficacious return to sport for an overhead athlete. However, the overall utilization and variation of ITPs are unknown in the physical therapy setting leading to potential inconsistencies in treatment paradigms. Objective: To determine if differences in practice patterns exist among active physical therapists of various experience levels with regard to years of experience and advanced certifications. Design: Cross-sectional survey study. Participants: A total of 133 licensed physical therapists consented to participate in an online-based survey. Experience groups were delineated based on years of practice (0-1, 1-5, 6-15, and 15+) and possession of advanced certification. Main Outcome Measures: For ranking-based data, a generalized linear mixed model was repeated across criteria response with a Bonferroni post hoc adjustment for pairwise comparisons made within and between groups (α < .05). For degree-based questions, chi-square analysis was used to compare response frequencies for options provided within each question. Results: A 76.7% response rate was achieved with 102 out of the 133 consenting individuals completed the survey. Significant differences (P < .05) were found with responses to both ranking-based and degree-based questions. However, across all groups, physical therapists agreed that throwing mechanics and customized ITP implementation were important for a successful return to throwing. Conclusions: There are inherent differences in ITP prescription among physical therapists with dissimilar experience levels. The possession of advanced certifications and years of practice seem to play a role in how interval programs are prescribed to overhead-throwing athletes. This study helps to identify differences in current physical therapy approaches toward the later stages of rehabilitation for throwing athletes. Further research should identify areas of improvement in physical therapist education as well as appropriate ITP prescription parameters to optimize care and treatment for this patient population.