Prevention of Non-Contact Anterior Cruciate Ligament Injuries among Youth Female Athletes: An Umbrella Review.

Anterior cruciate ligament (ACL) injuries account for a large percentage of knee injuries, disproportionately affecting female athletes. To help health professionals stay current, we performed an umbrella review to evaluate the effectiveness of ACL injury prevention programs in reducing non-contact ACL injury rates, determine the effective components within interventions, and provide clinical recommendations. Twelve databases (Medline, Embase, Cochrane Database of Systematic Reviews, SPORTDiscus, Cumulative Index to Nursing and Allied Health Literature, PEDro, Web of Science Core Collection, Epistemonikos, TRIP, BC Guidelines and Protocols, CPG Infobase, ProQuest Dissertations and Theses Global) were searched in May 2021 to identify relevant systematic reviews and meta-analyses. Four databases were searched again in September 2021 to identify recent primary literature. Non-contact ACL injury data were extracted to calculate incidence rate ratios (IRRs) and these were combined using an inverse variance random-effects model. A qualitative assessment of included reviews was performed. The methodological quality of the studies was assessed using a Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) or Cochrane Risk-of-Bias Tool for Randomized Trials (RoB 2). Sixteen reviews and two primary studies met the inclusion criteria. Across 11 primary studies, prevention programs were effective in reducing non-contact ACL injuries by 64% (IRR = 0.36 (95% CI: 0.18-0.70)). A multi-faceted exercise program, beginning in the pre-season and containing at least three exercise types, may be beneficial in reducing ACL injury risk.

Evaluating the Accuracy of Using Fixed Ranges of METs to Categorize Exertional Intensity in a Heterogeneous Group of Healthy Individuals: Implications for Cardiorespiratory Fitness and Health Outcomes.

BACKGROUND: Appropriate quantification of exertional intensity remains elusive. OBJECTIVE: To compare, in a large and heterogeneous cohort of healthy females and males, the commonly used intensity classification system (i.e., light, moderate, vigorous, near-maximal) based on fixed ranges of metabolic equivalents (METs) to an individualized schema based on the exercise intensity domains (i.e., moderate, heavy, severe). METHODS: A heterogenous sample of 565 individuals (females 165; males 400; age range 18-83 years old) were included in the study. Individuals performed a ramp-incremental exercise test from which gas exchange threshold (GET), respiratory compensation point (RCP) and maximum oxygen uptake (VO2max) were determined to build the exercise intensity domain schema (moderate = METs ≤ GET; heavy = METs > GET but ≤ RCP; severe = METs > RCP) for each individual. Pearson's chi-square tests over contingency tables were used to evaluate frequency distribution within intensity domains at each MET value. A multi-level regression model was performed to identify predictors of the amplitude of the exercise intensity domains. RESULTS: A critical discrepancy existed between the confines of the exercise intensity domains and the commonly used fixed MET classification system. Overall, the upper limit of the moderate-intensity domain ranged between 2 and 13 METs and of the heavy-intensity domain between 3 and 18 METs, whereas the severe-intensity domain included METs from 4 onward. CONCLUSIONS: Findings show that the common practice of assigning fixed values of METs to relative categories of intensity risks misclassifications of the physiological stress imposed by exercise and physical activity. These misclassifications can lead to erroneous interpretations of the dose-response relationship of exercise and physical activity.

A Critical Evaluation of Current Methods for Exercise Prescription in Women and Men.

Common methods to prescribe exercise intensity are based on fixed percentages of maximum rate of oxygen uptake (V˙O2max), peak work rate (WRpeak), maximal HR (HRmax). However, it is unknown how these methods compare to the current models to partition the exercise intensity spectrum. PURPOSE: Thus, the aim of this study was to compare contemporary gold-standard approaches for exercise prescription based on fixed percentages of maximum values to the well-established, but underutilized, "domain" schema of exercise intensity. METHODS: One hundred individuals participated in the study (women, 46; men, 54). A cardiopulmonary ramp-incremental test was performed to assess V˙O2max, WRpeak, HRmax, and the lactate threshold (LT), and submaximal constant-work rate trials of 30-min duration to determine the maximal lactate steady-state (MLSS). The LT and MLSS were used to partition the intensity spectrum for each individual in three domains of intensity: moderate, heavy, and severe. RESULTS: V˙O2max in women and men was 3.06 ± 0.41 L·min and 4.10 ± 0.56 L·min, respectively. Lactate threshold and MLSS occurred at a greater %V˙O2max and %HRmax in women compared with men (P < 0.05). The large ranges in both sexes at which LT and MLSS occurred on the basis of %V˙O2max (LT, 45%-74%; MLSS, 69%-96%), %WRpeak (LT, 23%-57%; MLSS, 44%-71%), and %HRmax (LT, 60%-90%; MLSS, 75%-97%) elicited large variability in the number of individuals distributed in each domain at the fixed-percentages examined. CONCLUSIONS: Contemporary gold-standard methods for exercise prescription based on fixed-percentages of maximum values conform poorly to exercise intensity domains and thus do not adequately control the metabolic stimulus.

Effects of the menstrual and oral contraceptive cycle phases on microvascular reperfusion.

NEW FINDINGS: What is the central question of this study? What are the effects of the menstrual (early follicular and mid-luteal) or monophasic oral contraceptive (inactive- and active-pill) cycle phases on vascular reperfusion of lower limb microvasculature in healthy, active women using the near-infrared spectroscopy (NIRS) vascular occlusion test (VOT) technique? What is the main finding and its importance? We demonstrated that vascular responsiveness in the lower limb microvasculature remained unchanged between the early follicular and mid-luteal phases of the menstrual cycle and inactive- and active-pill phases of the oral contraceptive cycle. These data support that controlling for the cycle phases, within the specific times evaluated in this study, might not be necessary when assessing NIRS-VOT reperfusion rates. ABSTRACT: The objective was to examine whether the menstrual or monophasic oral contraceptive cycle phases affect microvascular responsiveness of the lower limb in healthy, active women. During the follicular or inactive-pill phase and the luteal or active-pill phase of the menstrual or oral contraceptive cycle, respectively, 15 non-oral contraceptive users (mean ± SD; 27 ± 6 years of age) and 15 monophasic oral contraceptive users (24 ± 4 years of age) underwent a lower-limb vascular occlusion test (5 min baseline, 5 min occlusion and 8 min post cuff release). Menstrual cycle phases were verified using an ovulation test. Vascular responsiveness was assessed by calculating the near-infrared spectroscopy-derived muscle oxygen saturation (StO2 ) reperfusion slope (slope 2 StO2 ) and the post occlusion StO2 area under the curve (StO2AUC ) of the tibialis anterior muscle. There were no differences in the reperfusion slope (as a percentage per second; follicular, 1.18 ± 0.48; luteal, 1.05 ± 0.48, inactive-pill, 0.95 ± 0.23; and active-pill, 0.87 ± 0.36; P = 0.09) and area under the curve (as a product of the percentage and seconds; follicular, 1067 ± 562; luteal, 918 ± 414, inactive-pill, 945 ± 702; and active-pill, 750 ± 519; P = 0.09) between the phases of the menstrual or oral contraceptive cycle, regardless of pill generation. The duration of oral contraceptive use was not associated with changes in slope 2 StO2 (r = 0.02, P = 0.94) or StO2AUC (r = -0.34, P = 0.22) between cycle phases. In conclusion, vascular responsiveness remained unchanged between the early follicular and mid-luteal phases of the menstrual cycle and the inactive-pill and active-pill phases of the oral contraceptive cycle.

Menstrual and oral contraceptive cycle phases do not affect submaximal and maximal exercise responses.

To examine whether the menstrual or monophasic oral contraceptive cycle phases affect submaximal (oxygen uptake ( V ˙ O2 ) kinetics, maximal lactate steady-state (MLSS)) and maximal ( V ˙ O2max , time-to-exhaustion (TTE)) responses to exercise in healthy, active women. During the mid-follicular or inactive-pill phase and the mid-luteal or active-pill phase of the respective menstrual or oral contraceptive cycle, 15 non-oral contraceptive users (mean and standard deviation (SD) (±): 27 ± 6 years; 171 ± 5 cm; 65 ± 7 kg) and 15 monophasic oral contraceptive users (24 ± 4 years; 169 ± 10 cm; 68 ± 10 kg) performed: one V ˙ O2 kinetics test; one ramp-incremental test; two to three 30-minute constant-load cycling trials to determine the power output corresponding to MLSS (MLSSp ), followed by a TTE trial. The phase of the menstrual or oral contraceptive cycle did not affect the time constant of the V ˙ O2 kinetics response (τ V ˙ O2 ) (mid-follicular, 20 ± 5 seconds and mid-luteal, 18 ± 3 seconds; inactive-pill, 22 ± 8 seconds and active-pill, 23 ± 6 seconds), V ˙ O2max (mid-follicular, 3.06 ± 0.32 L min-1 and mid-luteal, 3.00 ± 0.33 L min-1 ; inactive-pill, 2.87 ± 0.39 L min-1 and active-pill, 2.87 ± 0.45 L min-1 ), MLSSp (mid-follicular, 181 ± 30 W and mid-luteal, 182 ± 29 W; inactive-pill, 155 ± 26 W and active-pill, 155 ± 27 W), and TTE (mid-follicular, 147 ± 42 seconds and mid-luteal, 128 ± 54 seconds; inactive-pill, 146 ± 70 seconds and active-pill, 139 ± 77 seconds) (P > .05). The rate of perceived exertion (RPE) at minute 30 of the MLSSp trials was greater in the mid-follicular phase (6.2 ± 1.5) compared with the mid-luteal phase (5.3 ± 1.4) for non-oral contraceptive users (P = .022). The hormonal fluctuations between the menstrual and oral contraceptive cycle phases had no detectable effects on submaximal and maximal exercise performance, even when RPE differed.