Transfusion of non-red blood cell blood products does not reduce survival following cardiac surgery.

OBJECTIVES: The literature supports the assertion that patients undergoing cardiac surgery who receive perioperative packed red blood cell (pRBC) transfusions have increased associated mortality. The aim of the current study is to assess whether there is an association between non-pRBC blood product transfusions and increased mortality. METHODS: Data from our center's Society of Thoracic Surgeons database included patients who underwent cardiac surgery from 2010 to 2018. Patients with pRBC transfusions or circulatory arrest were excluded. Propensity matching was performed (1:1; caliper = 0.2 times the standard deviation of logit of propensity score). Kaplan-Meier estimates and Cox regression were used. Cardiac transplant, ventricular assist devices, transcatheter aortic valves, and patients who had experienced circulatory arrest were excluded from this analysis. RESULTS: A total of 8042 patients met criteria for analysis. Following propensity matching (1:1), 395 patients requiring perioperative non-pRBC blood products (platelets, fresh-frozen plasma, and cryoprecipitate) were matched with 395 nontransfusion patients, yielding equitable patient cohorts. Median follow-up was 4.5 (3.0-6.4) years. Patients received platelets (327 [82.8%]), fresh-frozen plasma (141 [35.7%]), and cryoprecipitate (60 [15.2%]). There was no significant difference in the postoperative mortality (6 [1.5%] vs 4 [1.0%]; P = .52). Reoperation (20 [5.0%] vs 8 [2.0%]; P < .02) and prolonged ventilation (36 [9.1%] vs 19 [4.8%]; P < .02) were greater in the transfusion group. Emergent operation (odds ratio [OR] 2.86 [1.72-4.78]; P < .001), intra-aortic balloon pump (OR 3.24 [1.64-6.39]; P < .001), and multivalve operation (OR 4.34 [2.83-6.67]; P < .001) were significantly associated with blood product use. Blood product transfusion (hazard ratio; 1.15 [0.89-1.48]; P = .3) was not significantly associated with increased mortality risk. There was no significant long-term survival difference between cohorts. CONCLUSIONS: Patients who undergo cardiac surgery requiring blood products alone, without pRBC transfusion, have similar postoperative and long-term survival compared with patients not requiring blood products. These data are based on a limited patient sample, and future studies will aid in improving the generalizability of these results.

Outcomes of reoperative aortic root surgery.

OBJECTIVE: The study objective was to determine the impact of reoperative aortic root replacement on short-term outcomes and survival. METHODS: This was a retrospective study of aortic root operations from 2010 to 2018. All patients with a complete aortic root replacement were included, and patients undergoing valve-sparing root replacements were excluded. Patients were dichotomized by first-time sternotomy versus redo sternotomy, which was defined as having had a prior sternotomy for whatever reason. Within the redo sternotomy group, reoperative aortic root replacements were identified, being defined as a complete aortic root replacement in patients with a prior aortic root replacement; 1:1 nearest neighbor propensity matching was used to compare outcomes across groups. Kaplan-Meier survival estimates were generated and compared using log-rank statistics. RESULTS: A total of 893 patients undergoing complete ARR were identified, of whom 595 (67%) underwent first-time sternotomy and 298 (33%) underwent redo sternotomy. After matching, postoperative outcomes were similar for the first-time and redo sternotomy groups, including operative mortality. Redo sternotomy was not associated with reduced survival after aortic root replacement compared with first-time sternotomy (P = .084), with 5-year survival of 73.7% for first-time sternotomy and 72.9% for redo sternotomy. In the redo sternotomy group (n = 298), 69 (23%) were reoperative aortic root replacements and 229 (77%) were first-time aortic root replacements. After matching, postoperative outcomes were similar for the first-time and reoperative aortic root replacement groups, including operative mortality. Reoperative aortic root replacement was not associated with reduced survival, compared with first-time aortic root replacement (P = .870), with 5-year survival of 67.9% for first-time aortic root replacement and 72.1% for reoperative aortic root replacement. CONCLUSIONS: Reoperative aortic root replacement can be performed safely and provides similar survival to first-time aortic root replacement.

Complete revascularization during coronary artery bypass grafting is associated with reduced major adverse events.

OBJECTIVE: Complete revascularization literature is limited by variance in patient cohorts and inconsistent definitions. The objective of the current study was to provide risk-adjusted outcomes for complete revascularization of significant nonmain-branch and main-branch vessel stenoses. METHODS: All patients that underwent first-time isolated coronary artery bypass grafting procedures were included. Kaplan-Meier survival estimates, cumulative incidence function, and Cox regression were used to analyze outcomes. RESULTS: The total population consisted of 3356 patients that underwent first-time isolated coronary artery bypass grafting. Eight hundred eighty-nine (26.5%) patients had incomplete and 2467 (73.5%) had complete revascularization. For main-branch vessels, 677 (20.2%) patients had incomplete revascularization and 2679 (79.8%) were completely revascularized. Following risk adjustment with inverse probability treatment weighting, all baseline characteristics were balanced (standardized mean difference, ≤ 0.10). On Kaplan-Meier estimates, survival at 1 year (94.6% vs 92.5%) and 5 years (86.5% vs 82.1%) (P = .05) was significantly better for patients who received complete revascularization. Freedom from major adverse cardiac and cerebrovascular events was significantly higher for the complete revascularization cohort at both 1 year (89.2% vs 84.2%) and 5 years (72.5% vs 66.7%) (P < .001). Complete revascularization (hazard ratio, 0.82; 95% confidence interval, 0.70-0.95; P = .01) was independently associated with a significant reduction in major adverse cardiac and cerebrovascular events. Incomplete revascularization of nonmain-branch vessels was not associated with mortality (hazard ratio, 1.14; 95% confidence interval, 0.74-1.8; P = .55) or major adverse cardiac and cerebrovascular events (hazard ratio, 0.90; 95% confidence interval, 0.66-1.24; P = .52). CONCLUSIONS: Complete surgical revascularization of all angiographically stenotic vessels in patients with multivessel coronary artery disease is associated with fewer major adverse events. Incomplete revascularization of nonmain-branch vessels is not associated with survival or major adverse cardiac and cerebrovascular events.

The Effect of COVID-19 on Cardiac Surgical Volume and its Associated Costs.

The COVID-19 pandemic significantly affected health care and in particular surgical volume. However, no data surrounding lost hospital revenue due to decreased cardiac surgical volume have been reported. The National Inpatient Sample database was used with decreases in cardiac surgery at a single center to generate a national estimate of decreased cardiac operative volume. Hospital charges and provided charge to cost ratios were used to create estimates of lost hospital revenue, adjusted for 2020 dollars. The COVID period was defined as January to May of 2020. A Gompertz function was used to model cardiac volume growth to pre-COVID levels. Single center cardiac case demographics were internally compared during January to May for 2019 and 2020 to create an estimate of volume reduction due to COVID. The maximum decrease in cardiac surgical volume was 28.3%. Cumulative case volume and hospital revenue loss during the COVID months as well as the recovery period totaled over 35 thousand cases and 2.5 billion dollars. Institutionally, patients during COVID months were younger, more frequently undergoing a CABG procedure, and had a longer length of stay. The pandemic caused a significant decrease in cardiac surgical volume and a subsequent decrease in hospital revenue. This data can be used to address the accumulated surgical backlog and programmatic changes for future occurrences.

The effect of receiving an award from the American Association for Thoracic Surgery Foundation.

Objective: This study's objective was to evaluate the scholastic and career effects of receiving either the American Association for Thoracic Surgery (AATS) Foundation research scholarship or surgical investigator program. Methods: AATS annual reports and recipient listings were used to generate the awardees. MEDLINE and SCOPUS were used to assess publications, citations, and H-Index for awardees. The National Institutes of Health (NIH) RePorter was used to collate NIH grant awarding to awardees. Publicly available institutional profiles were used to assess promotion status and leadership positions. Results: Awardees of the research scholarship had a median of 4733 citations and a median H-Index of 33. The surgical investigator program recipients had a median of 1346 citations with a median H-Index of 17. Across both funding mechanisms, 45% secured subsequent NIH funding. Most awardees received an academic promotion, with 62% of the research scholarship awardees promoted to full professor and 37% of the surgical investigator program to associate professor. Approximately half (48%) of all awardees hold leadership positions, with most being a clinical director or division chief. Conclusions: Receiving the AATS Foundation research scholarship or surgical investigator program positions early-career cardiothoracic surgeons for a promising future in academic surgery.

Finding a rhythm: Relating ultra-short-term heart rate variability measures in healthy young adults during rest, exercise, and recovery.

Ultra-short-term (UST; <5 min) heart rate variability (HRV) is increasingly used to indirectly assess autonomic nervous system modulation and physical health. However, UST HRV estimates may vary with measurement technique, physiological state, and data preprocessing. The purpose of this investigation was to assess the information content of UST HRV and its sensitivity to different physiological states and preprocessing techniques. 26 time, frequency, and non-linear HRV measures were determined in 80 healthy men (age: 22.1 ± 3.7 yr) and 25 women (age: 19.4 ± 2.8 yr) from 2-min ECG recordings during seated and standing rest, low-intensity exercise, and seated recovery after maximal exercise. For men, HRV measures obtained during each condition were further analyzed with principal component analysis, k-means clustering, and one-way ANCOVAs. Backward stepwise regression was used to determine the ability of UST HRV to predict aerobic fitness. The sensitivity of UST HRV estimates to different artifact correction procedures was determined with intraclass correlation coefficients. Compared with men, women displayed HRV characteristics suggestive of greater vagal modulation. Nearly 80% of HRV information content was distilled into three principal components comprised of similar measures across conditions. K-means clusters varied in composition and HRV characteristics but not aerobic fitness, which was best predicted by HRV during standing rest. HRV estimates differed depending on artifact correction procedures but were generally similar after individualized correction. Our results indicate that UST HRV measures display redundancy but convey state-specific information and do not strongly predict aerobic fitness in healthy men. Most UST HRV measures are robust to slight differences in artifact correction procedures.

Men and women trainers equally effective at promoting exercise adherence, self-efficacy, and fitness in women.

BACKGROUND: This study examined the effect of a personal trainer's sex on self-efficacy and fitness in woman clients. METHODS: Women (N.=28; mean age, 41.6±15.0 years; height, 153.49±28.11 cm; BMI, 25.9±6.4 kg/m2) completed a perceptual scale of self-efficacy (BARSE) and fitness tests before and after a training program. Trainers (men and women) met one-on-one with the volunteers on a biweekly basis for 8 weeks. Univariate analyses of change scores and repeated measures analysis of variance with Fisher's LSD pairwise comparisons tested changes in dependent variables by trainer sex. RESULTS: Significant increases were seen in (mean±SE; change for men trainers; change for woman trainers): self-efficacy (7.3±3.4; 7.3±2.7%); leg press strength (18.2±3.7; 16.4±3.3 kg); seated row (6.1±1.5; 5.3±1.3 kg); muscular endurance in 60° flexion hold (20.5±5.8; 24.8±5.0 s) and wall-sit (19.9±6.4; 33.5±5.8 s); but not flexibility (V-sit, 7.11±5.51; 4.23±4.50 cm). Chest press strength significantly increased for women trainers only (2.7±2.2; 5.3±1.8 kg). Despite this, there were no significant differences for any variable in the change from pre-to-post based on the sex of the trainer. CONCLUSIONS: Both men and woman-led training was effective for increasing markers of self-efficacy and fitness in woman clients.

Midterm Outcomes of Stented Versus Stentless Bioprosthetic Valves After Aortic Root Replacement.

To determine the impact of aortic root replacement (ARR) with a stentless bioprosthetic valve on midterm outcomes compared to a stented bioprosthetic valve-graft conduit. This was an observational study of aortic root operations from 2010 to 2018. All patients with a complete ARR for nonendocarditis reasons were included, while patients undergoing valve-sparing root replacements or primary aortic valve replacement or repair were excluded. Of the patients with a complete ARR, bioprosthetic valve implants were included, while mechanical valve implants were excluded. Patients were dichotomized into the stented ARR group and the stentless ARR group. A total of 1:1 nearest neighbor propensity matching was employed to assess the association of stentless valves with short-term and midterm outcomes. A total of 455 patients underwent a complete ARR with a bioprosthetic valve implant for nonendocarditis reasons, of which 212 (46.6%) received a stented valve, while 243 (53.4%) received a stentless valve. After matching, postoperative outcomes were similar across each group (P > 0.05), including operative mortality and adverse neurologic events. Median follow-up for the entire cohort was 4.41 years (95% CI: 4.01, 4.95). At 1 year follow-up, aortic regurgitation ≥ 2+ and ejection fraction were similar across each group (P > 0.05); however, the stentless valve group had lower aortic valve velocity and transvalvular pressure gradient. Finally, reoperations and survival were similar for each group over the study's follow-up (P > 0.05). Stentless valves may provide hemodynamic benefits after ARR; however, the clinical impact of those benefits for survival and reoperation may not yet be evident in the midterm.

Cardiac surgery in the afternoon is not associated with increased operative morbidity and mortality.

BACKGROUND: Time of day for surgical procedures has been a topic of considerable controversy, with some suggesting that later operating times are associated with worse outcomes. METHODS: All patients who underwent open cardiac surgery from 2011 to 2018 were included. Patients that had ventricular assist devices, heart transplant, transcatheter aortic valves, aortic dissections, and emergent operations were excluded. Primary outcomes included postoperative mortality and survival; secondary outcomes included postoperative complications and readmission. RESULTS: The initial patient population consisted of 7883 patients who underwent index cardiac surgery. Following propensity matching (3:1), there were 2569 patients in the a.m. cohort (7-11 a.m.) and 860 patients in the p.m. cohort (3-11 p.m.). All baseline characteristics were matched to equivalent proportions. Total intensive care unit time following surgery was longer for the a.m. cohort (46.5 vs. 40.0 h; p<.001). Otherwise, there was no significant difference between cohorts including operative mortality (1.83% vs 2.21%; p= .48). On multivariable analysis, p.m. surgery was not significantly associated with 30 days mortality (hazard ratio [HR]: 0.96 [0.60, 1.53]; p= .86] or mortality over the study follow-up (HR: 0.87 [0.73, 1.03]; p= .10]. For propensity-matched cohorts, Kaplan-Meier survival at 30 days (97.9% vs. 97.4%; p= .44), 1 (93.4% vs 93.9%; p= .51), and 5 years (80.9% vs. 80.2%; p= .84) was not significantly different between cohorts. CONCLUSION: Short- and long-term mortality, hospital readmission, and postoperative complications were not significantly different between patients that underwent cardiac surgery starting in the a.m. versus patients who had cases that started in the afternoon.

Differences in brain structure and theta burst stimulation-induced plasticity implicate the corticomotor system in loss of function after musculoskeletal injury.

Traumatic musculoskeletal injury (MSI) may involve changes in corticomotor structure and function, but direct evidence is needed. To determine the corticomotor basis of MSI, we examined interactions among skeletomotor function, corticospinal excitability, corticomotor structure (cortical thickness and white matter microstructure), and intermittent theta burst stimulation (iTBS)-induced plasticity. Nine women with unilateral anterior cruciate ligament rupture (ACL) 3.2 ± 1.1 yr prior to the study and 11 matched controls (CON) completed an MRI session followed by an offline plasticity-probing protocol using a randomized, sham-controlled, double-blind, cross-over study design. iTBS was applied to the injured (ACL) or nondominant (CON) motor cortex leg representation (M1LEG) with plasticity assessed based on changes in skeletomotor function and corticospinal excitability compared with sham iTBS. The results showed persistent loss of function in the injured quadriceps, compensatory adaptations in the uninjured quadriceps and both hamstrings, and injury-specific increases in corticospinal excitability. Injury was associated with lateralized reductions in paracentral lobule thickness, greater centrality of nonleg corticomotor regions, and increased primary somatosensory cortex leg area inefficiency and eccentricity. Individual responses to iTBS were consistent with the principles of homeostatic metaplasticity; corresponded to injury-related differences in skeletomotor function, corticospinal excitability, and corticomotor structure; and suggested that corticomotor adaptations involve both hemispheres. Moreover, iTBS normalized skeletomotor function and corticospinal excitability in ACL. The results of this investigation directly confirm corticomotor involvement in chronic loss of function after traumatic MSI, emphasize the sensitivity of the corticomotor system to skeletomotor events and behaviors, and raise the possibility that brain-targeted therapies could improve recovery.NEW & NOTEWORTHY Traumatic musculoskeletal injuries may involve adaptive changes in the brain that contribute to loss of function. Our combination of neuroimaging and theta burst transcranial magnetic stimulation (iTBS) revealed distinct patterns of iTBS-induced plasticity that normalized differences in muscle and brain function evident years after unilateral knee ligament rupture. Individual responses to iTBS corresponded to injury-specific differences in brain structure and physiological activity, depended on skeletomotor deficit severity, and suggested that corticomotor adaptations involve both hemispheres.

Mild hypothermia versus normothermia in patients undergoing cardiac surgery.

Objective: Temperature during cardiopulmonary bypass (CPB) for cardiac surgery has been controversial. The aim of the current study is to compare the outcomes for patients with mild hypothermia versus normothermic CPB temperatures. Methods: All patients who underwent cardiac surgery with CPB and temperatures ≥32°C from 2011 to 2018 were included, which consisted of mild hypothermia (32°C-35°C) and normothermia (>35°C) cohorts. Propensity matching (1:1) was performed for risk adjustment. Primary outcomes included operative and long-term survival. Secondary outcomes included postoperative complications. Results: A total of 6525 patients comprised 2 cohorts: mild hypothermia (32°C-35°C; n = 3148) versus normothermia (>35°C; n = 3377). Following adjustment for surgeon preference, there were 1601 propensity-matched patients who had similar baseline characteristics (standard mean difference, ≤0.10), including CPB time, crossclamp time, and intra-aortic balloon pump placement. Kaplan-Meier analysis showed no difference in long-term survival (82.6% vs 81.6%; P = .81). Over a median follow-up of 4.4 years, there were no differences in overall mortality (18.1% vs 18.1%; P = 1.1) or readmission (50.3% vs 48.3%; P = .2). Acute renal failure (3.7% vs 2.4%; P = .03) and intensive care unit hours (46.5 vs 45.1; P = .04) were significantly higher with hypothermia. There was no difference between cohorts for postoperative stroke (2.0% vs 2.0%; P = 1.0), reoperation (5.9% vs 6.0%; P = .9), or operative intra-aortic balloon pump placement (1.7% vs 1.8%; P = .9). Conclusions: Patients with mild hypothermia during CPB had increased postoperative renal failure and length of intensive care unit stay. Although there was no difference in long-term survival, mild hypothermia does not appear to offer patients appreciable benefits, compared with normothermia.

Permanent pacemaker placement following valve surgery is not independently associated with worse outcomes.

Background: Permanent pacemaker placement (PPM) is associated with morbidity following cardiac surgery. This study identified associations between PPM placement and 5-year outcomes for patients that require PPM following valvular surgery. Methods: All patients who underwent valvular surgery at our medical center from 2011 to 2018 were considered for analysis. Multivariable analysis identified associations between PPM placement, mortality, and readmissions. Primary outcomes were operative complications and mortality. Secondary outcomes included 5-year survival and readmission. Results: A total of 175 (4.86%) of 3602 valvular surgery patients required postoperative PPM. The PPM cohort had significantly worse baseline comorbidities, including greater Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) scores (3.8 vs 2.4 P < .0001). The PPM cohort had greater rates of blood product transfusion, prolonged ventilation, and new-onset atrial fibrillation. PPM placement was significantly associated with third-degree heart block (5.26; 95% confidence interval [95% CI], 1.00-27.53; P = .0496), ventricular fibrillation/tachycardia (3.90; 95% CI, 1.59-9.59; P = .01), and atrial fibrillation/flutter (1.53; 95% CI, 1.05-2.24; P = .03). On Kaplan-Meier estimates, 5-year survival (68.8% vs 83.1%; P = 01) was significantly reduced in the PPM cohort. Five-year all-cause readmission (60.4% vs 50.04%; P = .01) and heart failure readmission (35.5% vs 20.1%; P < .000) occurred more frequently in the PPM cohort. On multivariable Cox regression analysis, PPM placement (hazard ratio, 1.12; 95% CI, 0.84-1.50; P = .444) was not an independent predictor of mortality. On competing risk analysis, PPM (hazard ratio, 1.33; 95% CI, 0.99-1.80; P = .062) was not a predictor of hospital readmission. Conclusions: Valvular surgery patients who required postoperative PPM had elevated baseline operative risk. However, PPM implantation was not associated with mortality or readmission.

Structural Connectome Disruptions in Military Personnel with Mild Traumatic Brain Injury and Post-Traumatic Stress Disorder.

Mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) are common in military populations and share numerous symptoms. Functional graph theory studies demonstrate altered small-world brain networks in mTBI and PTSD, but little is known about structural covariance networks or the potentially distinct topology of mTBI-PTSD comorbidity. The purpose of this study was to compare brain structural covariance networks in healthy active duty military service members (CON) to those with PTSD, mTBI, and mTBI-PTSD. Seventy-six service members (31 CON, 14 PTSD, 12 mTBI, 19 mTBI-PTSD) completed clinical questionnaires and structural magnetic resonance imaging scans. Cortical thickness-derived adjacency matrices were used to determine structural covariance network topologies. Pairwise comparisons for characteristic path length, clustering coefficient, modularity (global), closeness centrality (nodal), and local efficiency were made across a range of network densities (5-35%) using non-parametric permutation tests. All clinical groups showed greater levels of arousal, stress, anxiety, and depression compared with CON. Global network analysis revealed greater clustering and local efficiency in PTSD compared with CON, whereas nodal analysis indicated altered path lengths and closeness centrality in fronto-limbic areas with mTBI-PTSD. Global and nodal graph outcomes suggest distinct pathophysiological manifestations of mTBI, PTSD, and mTBI-PTSD in structural brain networks. Greater network segregation and nodal differences in fronto-limbic areas may be tied to emotional fluctuations.

Constitutive and Stress-Induced Psychomotor Cortical Responses to Compound K Supplementation.

Isolated ginsenoside metabolites such as Compound K (CK) are of increasing interest to consumer and clinical populations as safe and non-pharmacological means to enhance psychomotor performance constitutively and in response to physical or cognitive stress. Nevertheless, the influence of CK on behavioral performance and EEG measures of cortical activity in humans is undetermined. In this double-blinded, placebo-controlled, counterbalanced within-group study, dose-dependent responses to CK (placebo, 160 and 960 mg) were assessed after 2 weeks of supplementation in nineteen healthy men and women (age: 39.9 ± 7.9 year, height 170.2 ± 8.6 cm, weight 79.7 ± 11.9 kg). Performance on upper- and lower-body choice reaction tests (CRTs) was tested before and after intense lower-body anaerobic exercise. Treatment- and stress-related changes in brain activity were measured with high-density EEG based on event-related potentials, oscillations, and source activity. Upper- (-12.3 ± 3.5 ms, p = 0.002) and lower-body (-12.3 ± 4.9 ms, p = 0.021) response times improved after exercise, with no difference between treatments (upper: p = 0.354; lower: p = 0.926). Analysis of cortical activity in sensor and source space revealed global increases in cortical arousal after exercise. CK increased activity in cortical regions responsible for sustained attention and mitigated exercise-induced increases in arousal. Responses to exercise varied depending on task, but CK appeared to reduce sensory interference from lower-body exercise during an upper-body CRT and improve the general maintenance of task-relevant sensory processes.

Prediction of exertional lower extremity musculoskeletal injury in tactical populations: protocol for a systematic review and planned meta-analysis of prospective studies from 1955 to 2018.

BACKGROUND: Musculoskeletal injuries (MSI) represent more than half of all injuries in tactical populations (i.e., military service and public safety workers including police, firefighters, emergency medical services (EMS)). Most lower extremity MSIs result from physical exertion during training, occupational tasks, and recreation. Such exertional lower extremity injuries (ELEI) produce a significant human and financial cost. Accordingly, significant efforts have been made to identify sensitive, specific, and reliable predictors of ELEI. There is a need to synthesize and evaluate the predictive value of risk factors for ELEI while addressing the influence of occupation, sex, exposure, injury characteristics, and study quality. Therefore, the purpose of this systematic review and planned meta-analysis is to evaluate risk factors for ELEI in tactical populations. METHODS: After the development of a search strategy, comprehensive searches will be conducted in MEDLINE, EMBASE, Cochrane, and CINAHL databases. Articles will be screened with a multi-user process and delimited to prospective comparative cohort studies that directly measure injury occurrence in the target population(s). Extracted data will be synthesized and assessed for reporting bias, meta-bias, and overall quality, with subgroup analyses to determine the influence of participant, injury, and exposure characteristics in addition to study quality. DISCUSSION: This systematic review and planned meta-analysis will comprehensively evaluate ELEI risk factors. Information gained will inform injury prevention protocols, facilitate the use of improved measurements, and identify requirements for future research. TRIAL REGISTRATION: The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018056977 ).

Prevention of exertional lower body musculoskeletal injury in tactical populations: protocol for a systematic review and planned meta-analysis of prospective studies from 1955 to 2018.

BACKGROUND: Exertional lower body musculoskeletal injuries (ELBI) cost billions of dollars and compromise the readiness and job performance of military service and public safety workers (i.e., tactical populations). The prevalence and burden of such injuries underscores the importance of prevention efforts during activities necessary to sustain core occupational competencies. Attempts to synthesize prevention techniques specific to tactical populations have provided limited insight on the comparative efficacy of interventions that do not modify physical training practices. There is also a need to assess the influence of sex, exposure, injury classification scheme, and study design. Thus, the primary purpose of the systematic review and planned meta-analysis detailed in this protocol is to evaluate the comparative efficacy of ELBI prevention strategies in tactical populations. METHODS: A systematic search strategy will be implemented in MEDLINE, EMBASE, Cochrane, and CINAHL. A multi-tiered process will be used to capture randomized controlled trials and prospective cohort studies that directly assess the prevention of ELBI in tactical population(s). Extracted data will be used to compare prevention strategies and assess the influence of heterogeneity related to occupation, sex, exposure, injury characteristics, and study quality. In addition, individual risk of bias, meta-bias, and the quality of the body of evidence will be rigorously tested. DISCUSSION: This systematic review and planned meta-analysis will comprehensively evaluate ELBI mitigation strategies in tactical populations, elucidate factors that influence responses to treatment, and assess the overall quality of the body of research. Results of this work will guide the prioritization of ELBI prevention strategies and direct future research efforts, with direct relevance to tactical, health and rehabilitation science, and human performance optimization stakeholders. SYSTEMATIC REVIEW REGISTRATION: The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018081799 ).

Acute resistance exercise stimulates sex-specific dimeric immunoreactive growth hormone responses.

PURPOSE: We sought to determine if an acute heavy resistance exercise test (AHRET) would elicit sex-specific responses in circulating growth hormone (GH), with untreated serum and serum treated with a reducing agent to break disulfide-bindings between GH dimers. METHODS: 19 untrained participants (nine men and ten women) participated in an acute heavy resistance exercise test using the back squat. Blood samples were drawn before exercise (Pre), immediate post (IP), +15 min (+15), and +30 min (+30) afterwards. Serum samples were chemically reduced using glutathione (GSH). ELISAs were then used to compare immunoreactive GH concentrations in reduced (+GSH) and non-reduced (-GSH) samples. Data were analyzed using a three-way (2 sex × 2 treatment × 4 time) mixed methods ANOVA, with significance set at p ≤ 0.05. RESULTS: GSH reduction resulted in increased immunoreactive GH concentrations when compared to non-reduced samples at Pre (1.68 ± 0.33 µg/L vs 1.25 ± 0.25 µg/L), IP (7.69 ± 1.08 µg/L vs 5.76 ± 0.80 µg/L), +15 min (4.39 ± 0.58 µg/L vs 3.24 ± 0.43 µg/L), and +30 min (2.35 ± 0.49 µg/L vs 1.45 ± 0.23 µg/L). Also, women demonstrated greater GH responses compared to men, and this was not affected by reduction. CONCLUSIONS: Heavy resistance exercise increases immunoreactive GH dimer concentrations in men and women, with larger increases in women and more sustained response in men. The physiological significance of a sexually dimorphic GH response adds to the growing literature on aggregate GH and may be explained by differences in sex hormones and the structure of the GH cell network.

The addition of beta-hydroxy-beta-methylbutyrate and isomaltulose to whey protein improves recovery from highly demanding resistance exercise.

OBJECTIVE: This study evaluated whether a combination of whey protein (WP), calcium beta-hydroxy-beta-methylbutyrate (HMB), and carbohydrate exert additive effects on recovery from highly demanding resistance exercise. METHODS: Thirteen resistance-trained men (age: 22.6 ± 3.9 years; height: 175.3 ± 12.2 cm; weight: 86.2 ± 9.8 kg) completed a double-blinded, counterbalanced, within-group study. Subjects ingested EAS Recovery Protein (RP; EAS Sports Nutrition/Abbott Laboratories, Columbus, OH) or WP twice daily for 2 weeks prior to, during, and for 2 days following 3 consecutive days of intense resistance exercise. The workout sequence included heavy resistance exercise (day 1) and metabolic resistance exercise (days 2 and 3). The subjects performed no physical activity during day 4 (+24 hours) and day 5 (+48 hours), where recovery testing was performed. Before, during, and following the 3 workouts, treatment outcomes were evaluated using blood-based muscle damage markers and hormones, perceptual measures of muscle soreness, and countermovement jump performance. RESULTS: Creatine kinase was lower for the RP treatment on day 2 (RP: 166.9 ± 56.4 vs WP: 307.1 ± 125.2 IU · L(-1), p ≤ 0.05), day 4 (RP: 232.5 ± 67.4 vs WP: 432.6 ± 223.3 IU · L(-1), p ≤ 0.05), and day 5 (RP: 176.1 ± 38.7 vs 264.5 ± 120.9 IU · L(-1), p ≤ 0.05). Interleukin-6 was lower for the RP treatment on day 4 (RP: 1.2 ± 0.2 vs WP: 1.6 ± 0.6 pg · ml(-1), p ≤ 0.05) and day 5 (RP: 1.1 ± 0.2 vs WP: 1.6 ± 0.4 pg · ml(-1), p ≤ 0.05). Muscle soreness was lower for RP treatment on day 4 (RP: 2.0 ± 0.7 vs WP: 2.8 ± 1.1 cm, p ≤ 0.05). Vertical jump power was higher for the RP treatment on day 4 (RP: 5983.2 ± 624 vs WP 5303.9 ± 641.7 W, p ≤ 0.05) and day 5 (RP: 5792.5 ± 595.4 vs WP: 5200.4 ± 501 W, p ≤ 0.05). CONCLUSIONS: Our findings suggest that during times of intense conditioning, the recovery benefits of WP are enhanced with the addition of HMB and a slow-release carbohydrate. We observed reductions in markers of muscle damage and improved athletic performance.

Developmental differences between boys and girls result in sex-specific physical fitness changes from fourth to fifth grade.

To better understand how developmental differences impact performance on a broad selection of common physical fitness measures, we examined changes in boys and girls from fourth to fifth grade. Subjects included 273 boys (age, 9.5 ± 0.6 years; height, 139.86 ± 7.52 cm; mass, 38.00 ± 9.55 kg) and 295 girls (age, 9.6 ± 0.5 years; height, 139.30 ± 7.19 cm; weight, 37.44 ± 9.35 kg). We compared anthropometrics, cardiorespiratory and local muscular endurance, flexibility, power, and strength. A mixed-method analysis of variance was used to compare boys and girls at the 2 time points. Pearson correlation coefficients were used to examine relationships between anthropometric and fitness measurements. Significance was set at p ≤ 0.05. Weight increased significantly (>10%) in both sexes, and girls became significantly taller than boys after growing 4.9% by fifth grade (vs. 3.5%). Both groups improved cardiorespiratory endurance and power, although boys performed better than girls at both time points. Boys were stronger in fourth grade, but girls improved more, leading to similar fifth-grade values. Girls were more flexible in fourth grade, but their significant decreases (∼32.4%) coupled with large improvements in boys (∼105%) resulted in similar fifth-grade scores. Body mass index (BMI) was positively correlated with run time regardless of grade or sex. Power was negatively correlated with BMI and run time in fourth grade. In conclusion, sex-specific differences in physical fitness are apparent before pubescence. Furthermore, this selection of measures reveals sexually dimorphic changes, which likely reflect the onset of puberty in girls. Coaches and teachers should account these developmental differences and their effects on anthropometrics and fitness in boys and girls.