Effects of a Flexible Workout System on Performance Gains in Collegiate Athletes.

ABSTRACT: Walts, CT, Murphy, SM, Stearne, DJ, Rieger, RH, and Clark, KP. Effects of a flexible workout system on performance gains in collegiate athletes. J Strength Cond Res 35(5): 1187-1193, 2021-Although research on the topic of periodization is abundant, investigations into different flexible periodization strategies in collegiate athletes are limited. Furthermore, how state of readiness (SOR) and workout autonomy affect training improvements is largely unknown. Therefore, the purpose of this study was to determine if a flexible periodization (FP) program would elicit significantly greater performance gains compared with a nonflexible periodization (NP) program (significance set p ≤ 0.05). A total of 32 male and female intercollegiate lacrosse players completed performance measures of vertical jump, sprinting speed, change of direction, and strength in bench press and deadlift. After pretesting, subjects were matched and randomly assigned to either FP (n = 17, age = 19.4 ± 1.4 years, height = 1.72 ± 0.10 m, mass = 72.29 ± 13.73 kg) or NP (n = 15, age = 19.9 ± 1.5 years, height = 1.72 ± 0.08 m, mass = 71.68 ± 13.55 kg) training groups. Both groups trained 3 days per week for 8 weeks. The NP group completed all workout volume and intensity as prescribed by a certified strength and conditioning coach. However, the FP group modified workout volume and intensity based on a daily SOR questionnaire. Although appreciable pretest to posttest improvements were observed for the entire subject cohort, multivariate analysis of variance (ANOVA) and a series of ANOVA tests demonstrated no statistically significant between-group differences for pretest to posttest changes on any of the performance tests (range of p values: 0.17-0.95). Although FP does not seem to be more effective than NP for eliciting performance gains, it may provide greater opportunities for autonomy while eliciting equivalent improvement levels. Therefore, flexible periodization based on SOR may be a viable training strategy.

The National Football League Combine 40-yd Dash: How Important is Maximum Velocity?

Clark, KP, Rieger, RH, Bruno, RF, and Stearne, DJ. The NFL combine 40-yard dash: how important is maximum velocity? J Strength Cond Res 33(6): 1542-1550, 2019-This investigation analyzed the sprint velocity profiles for athletes who completed the 40-yard (36.6 m) dash at the 2016 National Football League (NFL) Combine. The purpose was to evaluate the relationship between maximum velocity and sprint performance, and to compare acceleration patterns for fast and slow athletes. Using freely available online sources, data were collected for body mass and sprint performance (36.6 m time with split intervals at 9.1 and 18.3 m). For each athlete, split times were used to generate modeled curves of distance vs. time, velocity vs. time, and velocity vs. distance using a monoexponential equation. Model parameters were used to quantify acceleration patterns as the ratio of maximum velocity to maximum acceleration (vmax/amax, or τ). Linear regression was used to evaluate the relationship between maximum velocity and sprint performance for the entire sample. In addition, athletes were categorized into fast and slow groups based on maximum velocity, with independent t-tests and effect size statistics used to evaluate between-group differences in sprint performance and acceleration patterns. Results indicated that maximum velocity was strongly correlated with sprint performance across 9.1, 18.3, and 36.6 m (r of 0.72, 0.83, and 0.94, respectively). However, both fast and slow groups accelerated in a similar pattern relative to maximum velocity (τ = 0.768 ± 0.068 seconds for the fast group and τ = 0.773 ± 0.070 seconds for the slow group). We conclude that maximum velocity is of critical importance to 36.6 m time, and inclusion of more maximum velocity training may be warranted for athletes preparing for the NFL Combine.

Predictive Validity of National Basketball Association Draft Combine on Future Performance.

Teramoto, M, Cross, CL, Rieger, RH, Maak, TG, and Willick, SE. Predictive validity of national basketball association draft combine on future performance. J Strength Cond Res 32(2): 396-408, 2018-The National Basketball Association (NBA) Draft Combine is an annual event where prospective players are evaluated in terms of their athletic abilities and basketball skills. Data collected at the Combine should help NBA teams select right the players for the upcoming NBA draft; however, its value for predicting future performance of players has not been examined. This study investigated predictive validity of the NBA Draft Combine on future performance of basketball players. We performed a principal component analysis (PCA) on the 2010-2015 Combine data to reduce correlated variables (N = 234), a correlation analysis on the Combine data and future on-court performance to examine relationships (maximum pairwise N = 217), and a robust principal component regression (PCR) analysis to predict first-year and 3-year on-court performance from the Combine measures (N = 148 and 127, respectively). Three components were identified within the Combine data through PCA (= Combine subscales): length-size, power-quickness, and upper-body strength. As per the correlation analysis, the individual Combine items for anthropometrics, including height without shoes, standing reach, weight, wingspan, and hand length, as well as the Combine subscale of length-size, had positive, medium-to-large-sized correlations (r = 0.313-0.545) with defensive performance quantified by Defensive Box Plus/Minus. The robust PCR analysis showed that the Combine subscale of length-size was a predictor most significantly associated with future on-court performance (p ≤ 0.05), including Win Shares, Box Plus/Minus, and Value Over Replacement Player, followed by upper-body strength. In conclusion, the NBA Draft Combine has value for predicting future performance of players.

Incorrect inference in prevalence trend analysis due to misuse of the odds ratio.

Because public health agencies usually monitor health outcomes over time for surveillance, program evaluation, and policy decisions, a correct health outcome trend analysis is vital. If the analysis is done incorrectly and/or results are misinterpreted, a faulty trend analysis could jeopardize key aspects of public health initiatives such as program planning, implementations, policy development, and clinical decision making. It is essential then that accurate health outcome trend analysis be implemented in any data-driven decision-making process. Unfortunately, there continues to be common statistical mistakes in prevalence trend analysis. In this article, using recently published results from the Pediatric Nutrition Surveillance System, we will show the effect that an incorrect trend analysis and subsequent interpretation of results can have. We will also propose more appropriate statistical processes, such as the log-binomial model, for these situations.

Anti-bovine herpesvirus and anti-bovine viral diarrhea virus antibody responses in pregnant Holstein dairy cattle following administration of a multivalent killed virus vaccine.

OBJECTIVE: To determine the effect of a commercially available multivalent killed virus vaccine on serum neutralizing (SN) and colostrum neutralizing (CN) antibodies against bovine herpesvirus (BHV) type 1 and bovine viral diarrhea virus (BVDV) types 1 and 2 in pregnant dairy cattle. ANIMALS: 49 Holstein dairy cattle. PROCEDURES :25 cattle were vaccinated (IM injection) at least 60 days prior to calving (ie, at the end of the lactation period or according to the expected calving date for heifers) and again 5 weeks later. The remaining 24 cattle were not vaccinated (control group). Titers of SN antibodies were measured at the 5-week time point. Titers of SN and CN antibodies were measured at parturition. RESULTS: 5 weeks after initial vaccination, titers of SN antibodies against BHV-1 and BVDV types 1 and 2 were 1:512, 1:128, and 1:2,048, respectively, in vaccinates and 1:64, 1:128, and 1:64, respectively, in unvaccinated controls. Equivalent SN antibody titers at parturition were 1:256, 1:64, and 1:512, respectively, in vaccinates and 1:128, 1:128, and 1:64, respectively, in controls. Median titers of CN antibodies against BHV-1 and BVDV types 1 and 2 were 1:1,280, 1:10,240, and 1:20,480, respectively, in vaccinates and 1:80, 1:1,280, and 1:2,560, respectively, in controls. CONCLUSIONS AND CLINICAL RELEVANCE: Titers of antibodies against viral respiratory pathogens were significantly enhanced in both serum (BHV-1 and BVDV type 2) and colostrum (BHV-1 and BVDV types 1 and 2) in cattle receiving a killed virus vaccine (with no adverse reactions) before parturition. To maximize protection of bovine neonates, this method of vaccination should be considered.

Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas.

OBJECTIVE: To investigate associations between age at gonadectomy and estimated risk or age at diagnosis of neoplastic and behavioral disorders in Vizslas. DESIGN: Retrospective cohort study. ANIMALS: 2,505 Vizslas born between 1992 and 2008. PROCEDURES: Data on demographics, gonadectomy status, and age at diagnosis of disease or disorder were obtained with an anonymous online survey and analyzed. RESULTS: Dogs gonadectomized at ≤ 6 months, between 7 and 12 months, or at > 12 months of age had significantly increased odds of developing mast cell cancer, lymphoma, all other cancers, all cancers combined, and fear of storms, compared with the odds for sexually intact dogs. Females gonadectomized at ≤ 12 months of age and males and females gonadectomized at > 12 months of age had significantly increased odds of developing hemangiosarcoma, compared with the odds for sexually intact dogs. Dogs gonadectomized at ≤ 6 months of age had significantly increased odds of developing a behavioral disorder. The younger the age at gonadectomy, the earlier the mean age at diagnosis of mast cell cancer, cancers other than mast cell, hemangiosarcoma, lymphoma, all cancers combined, a behavioral disorder, or fear of storms. CONCLUSIONS AND CLINICAL RELEVANCE: Additional studies are needed on the biological effects of removing gonadal hormones and on methods to render dogs infertile that do not involve gonadectomy. Veterinarians should discuss the benefits and possible adverse effects of gonadectomy with clients, giving consideration to the breed of dog, the owner's circumstances, and the anticipated use of the dog.

Exercising videoendoscopic evaluation of 45 horses with respiratory noise and/or poor performance after laryngoplasty.

OBJECTIVE: To (1) assess upper airway function by videoendoscopy in horses performing poorly after laryngoplasty and (2) establish whether dynamic collapse of the left arytenoid can be predicted by the degree of resting postsurgical abduction. STUDY DESIGN: Case series. ANIMALS: Horses that had left laryngoplasty (n=45). METHODS: Medical records (June 1993-December 2007) of horses evaluated for abnormal respiratory noise and/or poor performance after laryngoplasty were reviewed. Horses with video recordings of resting and exercising upper airway endoscopy were included and postsurgical abduction categorized. Horses with immediate postoperative endoscopy recordings were also evaluated and postsurgical abduction categorized. Relationships between resting postsurgical abduction and historical information with exercising endoscopic findings were examined. RESULTS: Dynamic collapse of the left arytenoid cartilage was probable in horses with no postsurgical abduction and could not be predicted in horses with grade 3 or 4 postsurgical abduction. Respiratory noise was associated with upper airway obstruction but was not specific for arytenoid collapse. Most horses with a left vocal fold had billowing of the fold during exercise. Other forms of dynamic collapse involved the right vocal fold, aryepiglottic folds, corniculate process of left arytenoid cartilage, dorsal displacement of soft palate, and pharyngeal collapse. Complex obstructions were observed in most examinations and in all horses with exercising collapse of the left arytenoid cartilage. CONCLUSIONS: There was no relationship between exercising collapse of the left arytenoid cartilage and grade 3 or 4 postsurgical abduction but was likely in horses with no abduction.

New technology, old standards: disparate activated clotting time measurements by the Hemochron Jr compared with the standard Hemochron.

BACKGROUND: Accurate control of the anticoagulation level is important for safe initiation of cardiopulmonary bypass. Using the Hemochron Jr., we consistently noted a higher than customary heparin dose required to achieve an activated clotting time (ACT) that, according to the literature and our quality standards, should be more than 480 seconds. This study was designed to determine whether there existed a significant difference in ACT values measured by the newer Hemochron Jr. and the older Hemochron 801 assay system. METHODS: A total of 30 patients underwent cardiovascular surgical procedures requiring heparinization (300 U/kg). Multiple samples for measurement of the ACT were obtained from all patients before heparinization, after heparinization, during cardiopulmonary bypass, and after protamine administration. Arterial samples were collected, and ACT was determined simultaneously on the same sample using both Hemochron Jr. and Hemochron 801. Activated clotting time data were analyzed with a linear mixed model using an unstructured variance-covariance matrix. RESULTS: Descriptive statistics on all heparinized patients revealed that the Hemochron Jr. yielded ACT results that on average were 121.28 seconds lower than the determination by the standard Hemochron 801 on the same sample of blood. This difference was -139.04 in on-pump cases and -90.51 in off-pump cases, primarily a function of the fact that higher heparin doses and therefore longer ACTs were used in patients having operations using the heart-lung machine. From the linear mixed model, the estimated average paired difference between the Hemochron Jr. and Hemochron 801 was found to be -86.03, yielding a highly significant test statistic (t(28) = -6.18; p < 0.0001). CONCLUSIONS: Lower ACT values determined by Hemochron Jr. are consistent with higher, clinically acceptable ACT values as measured by the Hemochron 801. These findings would suggest that safe levels of anticoagulation are determined in part by the specific assay used.

Analysis of clustered binary outcomes using within-cluster paired resampling.

Conditional logistic regression (CLR) is useful for analyzing clustered binary outcome data when interest lies in estimating a cluster-specific exposure parameter while treating the dependency arising from random cluster effects as a nuisance. CLR aggregates unmeasured cluster-specific factors into a cluster-specific baseline risk and is invalid in the presence of unmodeled heterogeneous covariate effects or within-cluster dependency. We propose an alternative, resampling-based method for analyzing clustered binary outcome data, within-cluster paired resampling (WCPR), which allows for within-cluster dependency not solely due to baseline heterogeneity. For example, dependency may be in part caused by heterogeneity in response to an exposure across clusters due to unmeasured cofactors. When both CLR and WCPR are valid, our simulations suggest that the two methods perform comparably. When CLR is invalid, WCPR continues to have good operating characteristics. For illustration, we apply both WCPR and CLR to a periodontal data set where there is heterogeneity in response to exposure across clusters.