Persistence of significant secondary mitral regurgitation post-cardiac resynchronization therapy and survival: a systematic review and meta-analysis : Mitral regurgitation and mortality post-CRT.

Cardiac resynchronization therapy (CRT) significantly reduces secondary mitral regurgitation (MR) in patients with severe left ventricular systolic dysfunction. However, uncertainty remains as to whether improvement in secondary MR correlates with improvement with mortality seen in CRT. We conducted a meta-analysis to determine the association of persistent unimproved significant secondary MR (defined as moderate or moderate-to-severe or severe MR) compared to improved MR (no MR or mild MR) post-CRT with all-cause mortality, cardiovascular mortality, and heart failure hospitalization. A systematic search of PubMed, EMBASE, and Cochrane Library databases till July 31, 2022 identified studies reporting clinical outcomes by post-CRT secondary MR status. In 12 prospective studies of 4954 patients (weighted mean age 66.8 years, men 77.8%), the median duration of follow-up post-CRT at which patients were re-evaluated for significant secondary MR was 6 months and showed significant relative risk reduction of 30% compared to pre-CRT. The median duration of follow-up post-CRT for ascertainment of main clinical outcomes was 38 months. The random effects pooled hazard ratio (95% confidence interval) of all-cause mortality in patients with unimproved secondary MR compared to improved secondary MR was 2.00 (1.57-2.55); p < 0.001). There was insufficient data to evaluate secondary outcomes in a meta-analysis, but limited data that examined the relationship showed significant association of unimproved secondary MR with increased cardiovascular mortality and heart failure hospitalization. The findings of this meta-analysis suggest that lack of improvement in secondary MR post-CRT is associated with significantly elevated risk of all-cause mortality and possibly cardiovascular mortality and heart failure hospitalization. Future studies may investigate approaches to address persistent secondary MR post-CRT to help improved outcome in this population.

Evolution and Prognosis of Tricuspid and Mitral Regurgitation Following Cardiac Implantable Electronic Devices. A Systematic Review and Meta-analysis.

BACKGROUND: Significant changes in tricuspid regurgitation (TR) and mitral regurgitation (MR) post-cardiac implantable electronic devices (CIED) are increasingly recognized. However, uncertainty remains as to whether risk of CIED-associated TR and MR differs with right ventricular pacing (RVP) via CIED with trans-tricuspid RV leads, compared to cardiac resynchronization therapy (CRT), conduction system pacing (CSP), and leadless pacing (LP). AIMS: Synthesize extant data on risk and prognosis of significant post-CIED TR and MR across pacing strategies. METHODS: We searched PubMed, EMBASE, and Cochrane Library databases published until October 31st, 2023. Significant post-CIED TR and MR were defined as ≥ moderate. RESULTS: Fifty-seven TR studies (N=13,723 patients) and 90 MR studies (N =14,387 patients) were included. For all CIED, risk of post-CIED TR increased (pooled odds ratio (OR)=2.46 and 95% CI=1.88-3.22), while risk of post-CIED MR reduced (OR=0.74, 95% CI=0.58-0.94) after 12 and 6 months of median follow-up respectively. RVP via CIED with trans-tricuspid RV leads was associated with increased risk of post-CIED TR (OR=4.54, 95% CI=3.14-6.57) and post-CIED MR (OR=2.24, 95% CI=1.18-4.26). Binarily, CSP did not alter TR risk (OR=0.37, 95% CI=0.13-1.02), but significantly reduced MR (OR =0.15, 95% CI=0.03-0.62). CRT did not significantly change TR risk (OR=1.09, 95% CI=0.55-2.17), but significantly reduced MR with prevalence pre-CRT of 43%, decreasing post-CRT to 22% (OR =0.49, 95% CI=0.40-0.61). There was no significant association of LP with post-CIED TR (OR=1.15, 95% CI=0.83-1.59) or MR (OR=1.31, 95% CI=0.72-2.39). CIED-associated TR was independently predictive of all-cause mortality (pooled hazard ratio (HR)=1.64, 95% CI=1.40-1.90) after median of 53 months. MR persisting post-CRT independently predicted all-cause mortality (HR=2.00, 95% CI=1.57-2.55) after 38 months. CONCLUSIONS: Our findings suggest that, when possible, adoption of pacing strategies which avoid isolated trans-tricuspid RV leads may be beneficial in preventing incident or deteriorating atrioventricular valvular regurgitation and might reduce mortality.

Dose-Response Effect of an Inertia Flywheel Postactivation Performance Enhancement Protocol on Countermovement Jump Performance.

The purpose of this study was to investigate the dose-response effect of a high-load, 6-repetition, maximum effort inertial flywheel (IFw) squat postactivation performance enhancement (PAPE) protocol on countermovement jump (CMJ) performance metrics. Thirteen subjects completed 5 squat testing sessions: 1 session to determine back-squat 6-repetition maximum, 1 session to determine 6-repetition maximum IFw load, and 3 sessions to investigate the dose-response effect of an IFw PAPE protocol set at the load determined in the second session. In the IFw PAPE sessions, subjects completed either 1, 2, or 3 sets of IFw squats, then performed 5 CMJs over 12 minutes (1, 3, 6, 9, and 12 min post-IFw). All CMJ tests were conducted on a force platform where CMJ performance outcomes and impulse variables were calculated. There was no main time or volume effect for jump height, contact time, reactive strength index, peak force, or any of the impulse variables. A main time effect was identified for flight time (P = .006, effect size = 0.24) and peak power (P = .001, effect size = 0.28). The lack of change in jump height may indicate that too much fatigue was generated following this near-maximal IFw squat protocol, thereby reducing the PAPE effect.

Assisted reality device to guide cardiac implantable device programming in distant rural areas.

BACKGROUND: Patients with cardiac implantable electronic devices (CIEDs) living in rural areas have difficulty obtaining follow-up visits for device interrogation and programming in specialized healthcare facilities. OBJECTIVE: To describe the use of an assisted reality device designed to provide front-line workers with real-time online support from a remotely located specialist (Realwear HTM-1; Realwear) during CIED assistance in distant rural areas. METHODS: This is a prospective study of patients requiring CIED interrogation using the Realwear HMT-1 in a remote rural population in Colombia between April 2021 and June 2022. CIED interrogation and device programming were performed by a general practitioner and guided by a cardiac electrophysiologist. Non-CIED-related medical interventions were allowed and analyzed. The primary objective was to determine the incidence of clinically significant CIED alerts. Secondary objectives were the changes medical interventions used to treat the events found in the device interrogations regarding non-CIED related conditions. RESULTS: A total of 205 CIED interrogations were performed on 139 patients (age 69 ± 14 years; 54% female). Clinically significant CIED alerts were reported in 42% of CIED interrogations, consisting of the detection of significant arrhythmias (35%), lead malfunction (3%), and device in elective replacement interval (3.9%). Oral anticoagulation was initiated in 8% of patients and general medical/cardiac interventions unrelated to the CIED were performed in 52% of CIED encounters. CONCLUSION: Remote assistance using a commercially available assisted reality device has the potential to provide specialized healthcare to patients in difficult-to-reach areas, overcoming current difficulties associated with RM, including the inability to change device programming. Additionally, these interactions provided care beyond CIED-related interventions, thus delivering significant social and clinical impact to remote rural populations.

Characteristics of patients with atrial high rate episodes detected by implanted defibrillator and resynchronization devices.

AIMS: Atrial high rate episodes (AHREs) are associated with increased risks of thromboembolism and cardiovascular mortality. However, the clinical characteristics of patients developing AHRE of various durations are not well studied. METHODS AND RESULTS: This was an ancillary analysis of the multicentre, randomized IMPACT trial. In the present analysis, we classified patients according to the duration of AHRE ≤6 min, >6 min to ≤6 h, >6 to ≤24 h and >24 h, and investigated the association between clinical factors and the development of each duration of AHRE. Of 2718 patients included in the trial, 945 (34.8%) developed AHRE. The incidence rates of each AHRE duration category were 5.4/100, 12.0/100, 6.8/100, and 3.3/100 patient-years, respectively. The incidence rates of AHRE >6 h were significantly higher in patients at high risk of thromboembolism (CHADS2 score ≥3) compared to those at low risk (CHADS2 score 1 or 2). Using Cox regression analysis, age ≥65 years and history of atrial fibrillation (AF) and/or atrial flutter (AFL) were risk factors for AHRE >6 min. In addition, hypertension was associated with AHRE >24 h (hazard ratio 2.13, 95% confidence interval 1.24-3.65, P = 0.006). CONCLUSION: Atrial high rate episode >6 min to ≤6 h were most prevalent among all AHRE duration categories. Longer AHREs were more common in patients at risk of thromboembolism. Age and history of AF/AFL were risk factors for AHRE >6 min. Furthermore, hypertension showed a strong impact on the development of AHRE >24 h rather than age.

Alterations in atrial electrogram amplitude as steady sinus rhythm transitions to paroxysmal atrial fibrillation during continuous monitoring in patients with implantable cardiac devices: Insights from the IMPACT study.

OBJECTIVES: We aimed to evaluate whether device measured amplitudes of atrial electrogram (AEGM) would change when measured in sinus rhythm (SR) transitioning to paroxysmal atrial fibrillation (AF) from previous steady SR, and significance of such change. METHODS: From the IMPACT trial's database we selected two groups; (A) those who developed AF (n = 164), and (B) propensity-matched control (n = 459) who stayed in SR during continuous Home Monitoring (HM) to compare AEGMs amplitudes at baseline SR and transition phase. RESULTS: During 420.0 ± 349.2 days (mean ± SD) from first postenrollment HM transmission to AF event transmission in Group A, and corresponding 515.3 ± 407.0 days in Group B, baseline and transition AEGM amplitude were 2.88 ± 1.146 and 2.74 ± 1.186 mV, respectively, for Group A (p = .1), and 2.88 ± 1.155 and 2.79 ± 1.145, respectively, for Group B (p < .005). Comparison of differences of AEGM amplitude, 0.14 ± 1.072 mV in Group A and 0.09 ± 0.893 mV in Group B were insignificant (p = .3). Age, sex, and hypertension identified as confounders had no association to AEGM changes (p = NS). CONCLUSIONS: Independent of age, sex, and hypertension, AEGMs amplitudes decline over a long period of time in patients with defibrillators and substrate for AF. The significance of such change remains unclear as it occurs whether patients develop AF or not, but raises a possibility of progressive atrial myopathy that patients with substrate for AF may be predisposed to.

Risk of ventricular arrhythmia in cardiac resynchronization therapy responders and super-responders: a systematic review and meta-analysis.

AIMS: Response to cardiac resynchronization therapy (CRT) is associated with improved survival, and reduction in heart failure hospitalization, and ventricular arrhythmia (VA) risk. However, the impact of CRT super-response [CRT-SR, increase in left ventricular ejection fraction (LVEF) to ≥ 50%] on VA remains unclear. METHODS AND RESULTS: We undertook a meta-analysis aimed at determining the impact of CRT response and CRT-SR on risk of VA and all-cause mortality. Systematic search of PubMed, EMBASE, and Cochrane databases, identifying all relevant English articles published until 31 December 2019. A total of 34 studies (7605 patients for VA and 5874 patients for all-cause mortality) were retained for the meta-analysis. The pooled cumulative incidence of appropriate implantable cardioverter-defibrillator therapy for VA was significantly lower at 13.0% (4.5% per annum) in CRT-responders, vs. 29.0% (annualized rate of 10.0%) in CRT non-responders, relative risk (RR) 0.47 [95% confidence interval (CI) 0.39-0.56, P < 0.0001]; all-cause mortality 3.5% vs. 9.1% per annum, RR of 0.38 (95% CI 0.30-0.49, P < 0.0001). The pooled incidence of VA was significantly lower in CRT-SR compared with CRT non-super-responders (non-responders + responders) at 0.9% vs. 3.8% per annum, respectively, RR 0.22 (95% CI 0.12-0.40, P < 0.0001); as well as all-cause mortality at 2.0% vs. 4.3%, respectively, RR 0.47 (95% CI 0.33-0.66, P < 0.0001). CONCLUSIONS: Cardiac resynchronization therapy super-responders have low absolute risk of VA and all-cause mortality. However, there remains a non-trivial residual absolute risk of these adverse outcomes in CRT responders. These findings suggest that among CRT responders, there may be a continued clinical benefit of defibrillators.

Watching for Disease: the Changing Paradigm of Disease Screening in the Age of Consumer Health Devices.

There has been a recent proliferation of consumer health devices (CHDs) that enable user-initiated screening for a variety of diseases. These devices represent a paradigm shift in the deployment of disease screening, a process that has historically been led by clinicians following the guidance of professional bodies. The detection of AF via CHDs is a contemporary example of this phenomenon and highlights several important implications of the shift of disease screening from clinicians to CHD users. These include responsibility for patient data and outcomes, healthcare costs and access, and an evolution of the patient-provider relationship. However, as CHD technologies mature and become more affordable, they have the potential to detect actionable subclinical disease and improve health. Rather than allow CHDs to enter the marketplace organically with the potential for unintended negative consequences, it is critical that clinical, research, and industry communities proactively collaborate and establish best practices for their use.

Choices enhance punching performance of competitive kickboxers.

While self-controlled practice has been shown to enhance motor learning with various populations and novel tasks, it remains unclear if such effects would be found with athletes completing familiar tasks. Study 1 used a single case-study design with a world-champion kickboxer. We investigated whether giving the athlete a choice over the order of punches would affect punching velocity and impact force. Separated by 1 min of rest, the athlete completed 2 rounds of 12 single, maximal effort punches (lead straight, rear straight, lead hook and rear hook) delivered to a punching integrator in a counterbalanced order over six testing days. In one round the punches were delivered in a predetermined order while in the second round the order was self-selected by the athlete. In the choice condition, the world champion punched with greater velocities (6-11 %) and impact forces (5-10 %). In Study 2, the same testing procedures were repeated with 13 amateur male kickboxers over 2 testing days. Similar to Study 1, the athletes punched with significantly greater velocities (6 %, p < 0.05) and normalised impact forces (2 %, p < 0.05) in the choice condition. These findings complement research on autonomy support in motor learning by demonstrating immediate advantages in force production and velocity with experienced athletes.

The effects of attentional focus instructions on punching velocity and impact forces among trained combat athletes.

Research indicates that instructing athlete's to focus on bodily movements (internal focus of attention [IFA]) may hinder performance, whereas instructing them to focus on the movement outcome (external focus of attention [EFA]) often enhances performance. Despite the importance of instructions in striking combat sports, limited research has examined the influence of IFA and EFA on performance in well-trained combat athletes. This study investigated the effects of different instructional cues on punching velocity (m · s-1) and normalised impact forces (N · kg-1) among intermediate (n = 8) and expert (n = 7) competitive boxers and kickboxers. Athletes completed three rounds of 12 maximal effort punches delivered to a punching integrator on three separate days. Day one was a familiarisation session with only control instructions provided. In the following two days athletes randomly received IFA, EFA or control instructions prior to each of the three rounds. Athletes punching with EFA were 4% faster and 5% more forceful than IFA (P < 0.05), and 2% faster and 3% more forceful than control (P < 0.05). Furthermore, experts punched 11% faster and with 13% greater force compared with intermediate athletes (P < 0.05). EFA led to a positive effect on punching performance and should be favoured over IFA and control instructions.

The Effects of the Removal of Electronic Devices for 48 Hours on Sleep in Elite Judo Athletes.

This study examined the effects of evening use of electronic devices (i.e., smartphones, etc.) on sleep quality and next-day athletic and cognitive performance in elite judo athletes. Over 6 consecutive days and nights, 23 elite Australian judo athletes were monitored while attending a camp at the Australian Institute of Sport (AIS). In 14 athletes, all electronic devices were removed on days 3 and 4 (i.e., for 48 hours: the "device-restricted group"), whereas 9 were permitted to use their devices throughout the camp (the "control group"). All athletes wore an activity monitor (Readiband) continuously to provide measures of sleep quantity and quality. Other self-reported (diary) measures included time in bed, electronic device use, and rate of perceived exertion during training periods. Cognitive performance (Cogstate) and physical performance (single leg triple hop test) were also measured. When considering night 2 as a "baseline" for each group, removal of electronic devices on nights 3 and 4 (device-restricted group) resulted in no significant differences in any sleep-related measure between the groups. When comparing actigraphy-based measures of sleep to subjective measures, all athletes significantly overestimated sleep duration by 58 ± 85 minutes (p = 0.001) per night and underestimated time of sleep onset by 37 ± 72 minutes (p = 0.001) per night. No differences in physical or cognitive function were observed between the groups. CONCLUSION: This study has shown that the removal of electronic devices for a period of two nights (48 hours) during a judo camp does not affect sleep quality or quantity or influence athletic or cognitive performance.

Perforator variability in the anterolateral thigh free flap: a systematic review.

OBJECTIVES: The use of free flaps greatly improves reconstruction options and quality of life for patients undergoing oncological resections. The anterolateral thigh (ALT) free flap is frequently used in the head and neck. The aim of this review was to provide a summary of published evidence assessing perforator anatomy of this flap. METHODS: A broad search was undertaken through the PubMed database using the terms "anterolateral thigh free flap" and "perforator". Search limits included English language and human subjects. Studies that examined more than or equal to ten patients were analysed. RESULTS: A total of 23 studies were identified, which included both clinical and cadaver studies. 1251 thighs were examined with the mean number of perforators ranging from 1.15 to 4.26. In the majority of cases, the descending branch of the lateral circumflex femoral artery was the dominant pedicle and took a musculocutaneous route. In some series, up to 5.4% of thighs were identified as having no cutaneous perforators. Venous data is limited with most studies reporting the presence of two concomitant veins of which the largest concomitant vein is selected for venous anastomoses. CONCLUSIONS AND FUTURE STUDIES: The ALT free flap is a reconstruction option in head and neck cancer. Adequate perforators for reconstruction are identified in the majority of cases. Increased anatomical perforator knowledge may lead to further uptake of ALT free flap reconstruction and improved intraoperative troubleshooting. Further studies investigating those patients with no perforators in the ALT may lead to improved clinical outcomes.

Randomized trial of atrial arrhythmia monitoring to guide anticoagulation in patients with implanted defibrillator and cardiac resynchronization devices.

AIMS: Atrial tachyarrhythmias (ATs) detected by implanted devices are often atrial fibrillation or flutter (AF) associated with stroke. We hypothesized that introduction and termination of anticoagulation based upon AT monitoring would reduce both stroke and bleeding. METHODS AND RESULTS: We randomized 2718 patients with dual-chamber and biventricular defibrillators to start and stop anticoagulation based on remote rhythm monitoring vs. usual office-based follow-up with anticoagulation determined by standard clinical criteria. The primary analysis compared the composite endpoint of stroke, systemic embolism, and major bleeding with the two strategies. The trial was stopped after 2 years median follow-up based on futility of finding a difference in primary endpoints between groups. A total of 945 patients (34.8%) developed AT, 264 meeting study anticoagulation criteria. Adjudicated atrial electrograms confirmed AF in 91%; median time to initiate anticoagulation was 3 vs. 54 days in the intervention and control groups, respectively (P < 0.001). Primary events (2.4 vs. 2.3 per 100 patient-years) did not differ between groups (HR 1.06; 95% CI 0.75-1.51; P = 0.732). Major bleeding occurred at 1.6 vs. 1.2 per 100 patient-years (HR 1.39; 95% CI 0.89-2.17; P = 0.145). In patients with AT, thromboembolism rates were 1.0 vs. 1.6 per 100 patient-years (relative risk -35.3%; 95% CI -70.8 to 35.3%; P = 0.251). Although AT burden was associated with thromboembolism, there was no temporal relationship between AT and stroke. CONCLUSION: In patients with implanted defibrillators, the strategy of early initiation and interruption of anticoagulation based on remotely detected AT did not prevent thromboembolism and bleeding. CLINICAL TRIAL REGISTRATION: IMPACT ClinicalTrials.gov identifier: NCT00559988 ( http://clinicaltrials.gov/ct2/show/NCT00559988?term=NCT00559988&rank=1 ).

Implementation of a Tranexamic Acid Protocol to Reduce Blood Loss During Cranial Vault Remodeling for Craniosynostosis.

OBJECTIVE: Pediatric cranial vault remodeling for repair of craniosynostosis is associated with significant blood loss and transfusion requirements. Beginning in 2011, the authors evaluated the impact tranexamic acid (TXA) on blood loss and blood product transfusion for children less than 15 months of age undergoing primary surgical repair of nonsyndromic single suture craniosynostosis. METHODS: Following institutional review board approval, the authors performed a retrospective study of all children undergoing surgical correction of craniosynostosis at Oregon Health & Science University from 2005 to 2015. All available records were reviewed, and patient data were collected from the time of preoperative evaluation until discharge, comparing patient and clinical variables before and after the implementation of perioperative TXA. RESULTS: Of a total of 259 patients with craniosynostosis, 187 had nonsyndromic single-suture involvement; 69 of these patients (36.9%) received TXA. A single surgical team (AAK and NRS) performed all operations. Median age at the time of surgery was 8.1 months (interquartile range [IQR] of 6.0-9.8 months). The TXA group had a significant reduction in estimated intraoperative blood loss (26 mL/kg versus 36 mL/kg, P <0.001), cell saver volume transfused 6 mL/kg versus 10 mL/kg, P <0.001), red cell transfusion volume (32 mL/kg versus 42 mL/kg, P <0.001), exposure to plasma transfusion (0% versus 24% P <0.001), exposure to cryoprecipitate transfusion (0% versus 16%, P <0.001), and exposure to platelet transfusion (0% versus 7.6% P = 0.03). Despite reduced red cell transfusion, the TXA-treated patients exhibited similar postoperative hematocrits (30.4 versus 30.3 P = 0.906) to those not treated with TXA. Use of TXA was associated with reduced length of stay (4 days IQR 3-4 versus 4 days IQR 4-5, P <0.001) and reduced postoperative output from surgically placed drains (181 mL versus 311 mL P <0.001). There was no difference in postoperative complications between groups and no deaths in either group. CONCLUSIONS: The introduction of TXA for nonsyndromic single-suture synostosis repair at our institution has significantly reduced blood loss and blood product and plasma transfusion during and following primary cranial vault remodeling for single suture craniosynostosis. Postoperative hematocrit was similar in the TXA-treated and untreated groups despite reduced red cell transfusion in the treated group. In addition, TXA use in this population has eliminated the need for plasma transfusion, and is associated with a shorter hospital stay. No difference in postoperative complications was observed. Our data provide support for further investigation of TXA treatment to improve clinical outcomes in children undergoing pediatric cranial vault remodeling.

Importance of Standardized DXA Protocol for Assessing Physique Changes in Athletes.

PURPOSE: The implications of undertaking DXA scans using best practice protocols (subjects fasted and rested) or a less precise but more practical protocol in assessing chronic changes in body composition following training and a specialized recovery technique were investigated. METHODS: Twenty-one male cyclists completed an overload training program, in which they were randomized to four sessions per week of either cold water immersion therapy or control groups. Whole-body DXA scans were undertaken with best practice protocol (Best) or random activity protocol (Random) at baseline, after 3 weeks of overload training, and after a 2-week taper. Magnitudes of changes in total, lean and fat mass from baseline-overload, overload-taper and baseline-taper were assessed by standardization (Δmean/SD). RESULTS: The standard deviations of change scores for total and fat-free soft tissue mass (FFST) from Random scans (2-3%) were approximately double those observed in the Best (1-2%), owing to extra random errors associated with Random scans at baseline. There was little difference in change scores for fat mass. The effect of cold water immersion therapy on baseline-taper changes in FFST was possibly harmful (-0.7%; 90% confidence limits ±1.2%) with Best scans but unclear with Random scans (0.9%; ±2.0%). Both protocols gave similar possibly harmful effects of cold water immersion therapy on changes in fat mass (6.9%; ±13.5% and 5.5%; ±14.3%, respectively). CONCLUSIONS: An interesting effect of cold water immersion therapy on training-induced changes in body composition might have been missed with a less precise scanning protocol. DXA scans should be undertaken with Best.

The Effects of Attentional Focusing Instructions on Force Production During the Isometric Midthigh Pull.

Verbal instructions play a key role in motor learning and performance. Whereas directing one's attention toward bodily movements or muscles (internal focus) tends to hinder performance, instructing persons to focus on the movement outcome, or an external object related to the performed task (external focus) enhances performance. The study's purpose was to examine whether focus of attention affects maximal force production during an isometric midthigh pull (IMTP) among 18 trained athletes (8F & 10M). Athletes performed 3 IMTP trials a day for 3 consecutive days. The first day was a familiarization session in which athlete's received only control instructions. The following 2 days athletes received either control, internal, or external focus of attention instructions in a randomized, within-subject design. Compared to performance with an internal focus of attention, athletes applied 9% greater force when using an external focus of attention (p < 0.001, effect size [ES] = 0.33) and 5% greater force with control instructions (p = 0.001, ES = 0.28). A small positive 3% advantage was observed between performances with an external focus of attention compared with control instructions (p = 0.03, ES = 0.13). Focusing internally on body parts and/or muscle groups during a movement task that requires maximal force hinders performance, whereas focusing on an object external to the self leads to enhanced force production, even when using a simple multijoint static task such as the IMTP.

Transfusion of cryopreserved packed red blood cells is safe and effective after trauma: a prospective randomized trial.

OBJECTIVES: To determine the safety and efficacy of cryopreserved packed red blood cell (CPRBC) transfusion in trauma patients. BACKGROUND: Liquid packed red blood cells (LPRBCs) have an abbreviated shelf-life and worsening storage lesion with age. CPRBCs are frozen 2 to 6 days after donation, stored up to 10 years, and are available for 14 days after thawing and washing. CPRBCs can be utilized in diverse settings, but the effect on clinical outcomes is unknown. METHODS: We performed a prospective, randomized, double-blind study at 5 level 1 trauma centers. Stable trauma patients requiring transfusion were randomized to young LPRBCs (≤14 storage days), old LPRBCs (>14 storage days), or CPRBCs. Tissue oxygenation (StO2), biochemical and inflammatory mediators were measured, and clinical outcomes were determined. RESULTS: Two hundred fifty-six patients with well-matched injury severity and demographics (P > 0.2) were randomized (84 young, 86 old, and 86 CPRBCs). Pretransfusion and final hematocrits were similar (P > 0.68). Patients in all groups received the same number of units postrandomization (2 [1-4]; P > 0.05). There was no difference in the change in tissue oxygenation between groups. CPRBCs contained less α2-macrogobulin, haptoglobin, C-reactive protein, and serum amyloid P (P < 0.001). Organ failure, infection rate, and mortality did not differ between groups (P > 0.2). CONCLUSIONS: Transfusion of CPRBCs is as safe and effective as transfusion of young and old LPRBCs and provides a mechanism to deliver PRBCs in a wide variety of settings.

Maximal Sprint Power in Road Cyclists After Variable and Nonvariable High-Intensity Exercise.

This study compared the sprint performance of professional cyclists after 10 minutes of variable (VAR) or nonvariable (N-VAR) high-intensity cycling with sprint performance in a rested state. Ten internationally competitive male cyclists (mean ± SD: age, 20.1 ± 1.3 years; stature, 1.81 ± 0.07 m; body weight, 69.5 ± 4.9 kg; and V[Combining Dot Above]O2peak, 72.5 ± 4.4 ml·kg·min) performed a 12-second maximal sprint in 3 conditions: (a) a rested state, (b) after 10 minutes of N-VAR cycling, and (c) after 10 minutes of VAR cycling. The intensity during the 10-minute efforts gradually increased to replicate power output observed in the final section of cycling road races. During the VAR cycling, participants performed short (2 seconds) accelerations at 80% of their sprint peak power, every 30 seconds. Average power output, cadence, and maximal heart rate (HR) during the 10-minute efforts were similar between conditions (5.3 ± 0.2 W·kg, 102 ± 1 rpm, and 93 ± 3% HRmax). Postexercise blood lactate concentration and sessional perceived exertion were also similar (8.3 ± 1.6 mmol·L, 15.4 ± 1.3 [6-20 scale]). Peak and average power output and cadence during the subsequent maximal sprint were not different between the 3 experimental conditions (p > 0.05). In conclusion, this study showed that neither the VAR nor the N-VAR 10-minute efforts ridden in this study impaired sprint performance in elite competitive cyclists.

Dairy-based preexercise meal does not affect gut comfort or time-trial performance in female cyclists.

Some athletes avoid dairy in the meal consumed before exercise due to fears about gastrointestinal discomfort. Regular exclusion of dairy foods may unnecessarily reduce intake of high quality proteins and calcium with possible implications for body composition and bone health. This study compared the effects of meals that included (Dairy) or excluded (Control) dairy foods on gastric comfort and subsequent cycling performance. Well-trained female cyclists (n = 32; mean ± SD; 24.3 ± 4.1 y; VO(2peak) 57.1 ± 4.9 ml/kg/min) completed two trials (randomized cross-over design) in which they consumed a meal (2 g/kg carbohydrate and 54 kJ/kg) 2 hr before a 90-min cycle session (80 min at 60% maximal aerobic power followed by a 10-min time trial; TT). The dairy meal contained 3 servings of dairy foods providing ~1350 mg calcium. Gut comfort and palatability were measured using questionnaires. Performance was measured as maximum mean power during the TT (MMP10(min)). There was no statistical or clinical evidence of an effect of meal type on MMP10(min) with a mean difference (Dairy - Control) of 4 W (95% CI [-2, 9]). There was no evidence of an association between pretrial gut comfort and meal type (p = .15) or between gut comfort delta scores and meal type postmeal (p = .31), preexercise (p = .17) or postexercise (p = .80). There was no statistical or clinical evidence of a difference in palatability between meal types. In summary, substantial amounts of dairy foods can be included in meals consumed before strenuous cycling without impairing either gut comfort or performance.

Fatigue is specific to working muscles: no cross-over with single-leg cycling in trained cyclists.

Fatigue induced via a maximal isometric contraction of a single limb muscle group can evoke a "cross-over" of fatigue that reduces voluntary muscle activation and maximum isometric force in the rested contralateral homologous muscle group. We asked whether a cross-over of fatigue also occurs when fatigue is induced via high-intensity endurance exercise involving a substantial muscle mass. Specifically, we used high-intensity single-leg cycling to induce fatigue and evaluated associated effects on maximum cycling power (P (max)) in the fatigued ipsilateral leg (FAT(leg)) as well as the rested contralateral leg (REST(leg)). On separate days, 12 trained cyclists performed right leg P (max) trials before and again 30 s, 3, 5, and 10 min after a cycling time trial (TT, 10 min) performed either with their right or left leg. Fatigue was estimated by comparing exercise-induced changes in P (max) and maximum handgrip isometric force (F (max)). Mean power produced during the right and left leg TTs did not differ (203 ± 8 vs. 199 ± 8 W). Compared to pre-TT, FAT(leg) P (max) was reduced by 22 ± 3 % at 30 s post-TT and remained reduced by 9 ± 2 % at 5 min post-TT (both P < 0.05). Despite considerable power loss in the FAT(leg), post-TT REST(leg) P (max) (596-603 W) did not differ from pre-TT values (596 ± 35 W). There were no alterations in handgrip F (max) (529-547 N). Our data suggest that any potential cross-over of fatigue, if present at all, was not sufficient to measurably compromise REST(leg) P (max) in trained cyclists. These results along with the lack of changes in handgrip F (max) indicate that impairments in maximal voluntary neuromuscular function were specific to working muscles.