"Are You Doing Any Sport Science?" A Brief Editorial.

This brief opinion-based editorial addresses what the authors perceive to be a fundamental issue in the application of sport science, and these issues are reflected by the question "Are you doing any sport science?" As sport science has grown within the United States, organizational sport science budgets have grown, with increasing interest in developing various sport science initiatives. While it is indeed an exciting time for sport science, the authors suggest that, too often, sport science pursuits are driven by commercially available technologies and viewed as an "add-on" instead of pursuing an integrated systematic approach to informing the training process.

Using Random Forest Regression to Determine Influential Force-Time Metrics for Countermovement Jump Height: A Technical Report.

ABSTRACT: Merrigan, JJ, Stone, JD, Wagle, JP, Hornsby, WG, Ramadan, J, Joseph, M, and Hagen, JA. Using random forest regression to determine influential force-time metrics for countermovement jump height: a technical report. J Strength Cond Res 36(1): 277-283, 2022-The purpose of this study was to indicate the most influential force-time metrics on countermovement jump (CMJ) height using multiple statistical procedures. Eighty-two National Collegiate Athletic Association Division I American football players performed 2 maximal-effort, no arm-swing, CMJs on force plates. The average absolute and relative (i.e., power/body mass) metrics were included as predictor variables, whereas jump height was the dependent variable within regression models (p < 0.05). Best subsets regression (8 metrics, R2 = 0.95) included less metrics compared with stepwise regression (18 metrics, R2 = 0.96), while explaining similar overall variance in jump height (p = 0.083). Random forest regression (RFR) models included 8 metrics, explained ∼93% of jump height variance, and were not significantly different than best subsets regression models (p > 0.05). Players achieved higher CMJs by attaining a deeper, faster, and more forceful countermovement with lower eccentric-to-concentric force ratios. An additional RFR was conducted on metrics scaled to body mass and revealed relative mean and peak concentric power to be the most influential. For exploratory purposes, additional RFR were run for each positional group and suggested that the most influential variables may differ across positions. Thus, developing power output capabilities and providing coaching to improve technique during the countermovement may maximize jump height capabilities. Scientists and practitioners may use best subsets or RFR analyses to help identify which force-time metrics are of interest to reduce the selectable number of multicollinear force-time metrics to monitor. These results may inform their training programs to maximize individual performance capabilities.

Effect of lactate consumption on exercise performance.

BACKGROUND: Maintenance of plasma glucose is important in endurance performance. Gluconeogenesis or carbohydrate ingestion maintain glucose after hepatic glycogen depletion. Lactate may also serve as a gluconeogenic precursor as well as a blood buffer. METHODS: To determine if an 8% carbohydrate (CHO) sports drink with and without a 2% lactate (L) solution increased endurance performance, peak power, and delayed blood acidosis, seven trained cyclists participated in a double-blind randomized study (6 males and 1 female) performed a bicycle test to determine max VO2max HR and the HR associated with the first respiratory exchange ratio (RER) value greater than 1.0 (target HR). Four bicycle rides to exhaustion, separated by one week, were done at a constant workload at a HR 10 beats below each subject's target HR. After a 12-hour fast, subjects received 100 g CHO 2-3 hrs before each test. Mean exercise heart rate was 86-87% max HR. During the final 30 s of each ride the Wingate power test was performed. Subjects consumed either (placebo, 2% L, 8% CHO or 8% CHO plus 2% L) every 20 min. Blood samples were collected before, every 30 min during and immediately following the test. RESULTS: No significant differences were observed in total time (placebo: 95.3 +/- 25.8, 2% lactate: 95.7 +/- 30.0, 8% CHO: 105.2 +/- 37.2, 8% CHO + 2% lactate: 89.0 +/- 28.1 min) or peak power (placebo: 798.2 +/- 241.1, 2% L: 750.1 +/- 279.2, 8% CHO: 789.4 +/- 353.5, 8% CHO + 2% L: 716.3 +/- 331.3 Watts) among drinks. There were no differences in insulin, glucose, pH and HCO3- after the power tests among the drinks. CONCLUSION: Exercise performance is unaffected by oral supplementation with lactate.

Hemostatic alterations with exercise conditioning in NIDDM.

Various parameters of coagulation and fibrinolysis were measured in 13 men (aged 54 +/- 3 yr) with non-insulin-dependent diabetes mellitus (NIDDM) before and after 12-14 wk of exercise training. Subjects exercised for 30 min 3 times/wk at 70% of maximum O2 consumption (VO2max). Training increased VO2max by 12.5% but did not alter body weight, relative body fat, blood pressure, cholesterol, triglycerides, or high-density lipoprotein cholesterol. Slight downward trends were apparent for fasting glucose and insulin, but glycosylated hemoglobin was unchanged. There were no changes in coagulation parameters of plasminogen, hematocrit, or alpha 2-antiplasmin. Plasma fibrinogen (303 +/- 24.2 vs. 256 +/- 12.3 mg/dl) and fibronectin (380 +/- 41.9 vs. 301 +/- 22.2 micrograms/ml) were significantly reduced (P less than 0.02) by exercise conditioning. Three assays of fibrinolytic activity (tissue plasminogen activator, euglobulin lysis time, and an isotopic measure of fibrinolysis) confirmed that neither basal fibrinolysis nor the fibrinolytic responses to venous occlusion and maximal exercise were significantly altered. Exercise conditioning may have antithrombotic effects in NIDDM by reducing plasma fibrinogen and fibronectin. Although the significance of the fall in fibronectin awaits further studies, the reduction in plasma fibrinogen gives a rationale for the use of exercise training in men with NIDDM.