Decreased Percent Body Fat but Not Body Mass is Associated with Better Performance on Combat Fitness Test in Male and Female Marines.

ABSTRACT: Pletcher, ER, Lovalekar, M, Coleman, LC, Beals, K, Nindl, BC, and Allison, KF. Decreased percent body fat but not body mass is associated with better performance on the Marine Corps Combat Fitness Test. J Strength Cond Res 37(4): 887-893, 2023-The military uses a variety of physical fitness tests to assess physical readiness. The Marine Corps designed the Combat Fitness Test (CFT) to emphasize functional fitness related to operational demands. The purpose of this study was to investigate the association between body mass (BM), fat free mass (FFM), and percent body fat (BF%) measured via air displacement plethysmography with CFT performance in male and female marines. Two-hundred 10 male (22.4 ± 2.6 years) and 84 female (22.6 ± 2.8 years) marines were grouped into quintiles according to BM (in kilograms), FFM (in kilograms), and BF%. Kruskal-Wallis test or 1-way analysis of variance were used to determine if significant differences in CFT total and component scores existed between the groups of subjects classified into quintiles of BM, FFM, and BF%. No significant differences in CFT scores were observed between BM quintile in either men or women. No significant differences in CFT scores were observed between FFM quintiles in men. Total CFT score ( p = 0.002), movement to contact (MTC; p = 0.014), maneuver under fire (MANUF; p = 0.008), and ammunition lift (AL; p = 0.014) were all significantly different among FFM quintiles in women. Total CFT score ( p = 0.007), MTC ( p = 0.001), and MANUF ( p = 0.022) were significantly different among BF% quintiles in men. Total CFT score ( p = 0.008), MTC ( p = 0.033), and AL ( p = 0.016) were significantly different among BF% quintiles in women. Male and female marines in the quintile with lowest BF% had better CFT scores than those in higher quintiles. Targeted physical training and nutrition considerations to optimize BF% may help improve military task performance.

Hydrodynamic Flow Characteristics of a Recirculating Pool: Examining the Ecological Validity for Training and Testing.

ABSTRACT: Krajewski, KT, Beethe, AZ, Dever, DE, Johnson, CD, Nindl, BC, Lovalekar, MT, Flanagan, SD, and Connaboy, C. Hydrodynamic flow characteristics of a recirculating pool: examining the ecological validity for training and testing. J Strength Cond Res 37(10): 2023-2031, 2023-Recirculating swimming flumes (RSFs) with elliptical multifeature designs have grown in popularity due to their multifunctionality for rehabilitation and training. Because of their smaller footprint, laboratories have adopted their use to investigate swimming and underwater treadmill running. However, little is known about the hydrodynamic characteristics of these RSFs and how they might influence outcomes. The purpose was to determine hydrodynamic flow characteristics of an RSF at the manufacturers' set "speeds" around the centroid of flow projection. Hydrodynamic velocity profiles were collected through a 3D profiling velocimeter, sampling at 200 Hz in an RSF. Data were collected 0.5 and 1.5 m from the projection channel at designated flume "speeds" of 30-95 (+99) in 5-unit increments. Velocity data were collected for 1 minute per trial (location × speed) to determine mean flow velocity (MFV) for 10, 20, 30, and 40 cm2 cross-sectional areas (CSAs). A two-way ANOVA was conducted comparing CSAs from the surface by distance from the current channel (4 × 2). Separate ANOVAs were conducted to assess differences in MFV across each CSA. Significant differences between flow CSAs indicated that MFV is less for a larger area at the same speed, indicative of variable and turbulent flow characteristics across the respective CSAs. Mean flow velocity was further diminished by distance from the flow channel as supported by the main effect, thus exposing an individual to variant flow velocities simultaneously. Limited stability of the flow velocity centroid could affect swim mechanics making the movement pattern no longer analogous to traditional pool and open water swimming, rather resembling swimming upstream in a river with turbulent flow.

Prevention of Lower Extremity Musculoskeletal Injuries in Tactical and First Responder Populations: A Systematic Review and Meta-Analysis of Randomized Trials From 1955 to 2020.

ABSTRACT: Sinnott, AM, Krajewski, KT, LaGoy, AD, Beckner, ME, Proessl, F, Canino, MC, Nindl, BC, Turner, RL, Lovalekar, MT, Connaboy, C, and Flanagan, SD. Prevention of lower extremity musculoskeletal injuries in tactical and first responder populations: A systematic review and meta-analysis of randomized trials from 1955 to 2020. J Strength Cond Res 37(1): 239-252, 2023-Lower extremity musculoskeletal injuries (LEMSIs) impose a significant burden on tactical and first responder populations. To determine the effectiveness of LEMSI prevention strategies, we performed a systematic review and meta-analysis of randomized controlled trials published in English from 1955 to 2020 (PROSPERO: CRD42018081799). MEDLINE, EMBASE, Cochrane, CINAHL, ProQuest, and DTIC databases were searched for trials that assigned military service members, police, firefighters, or paramedics to LEMSI prevention interventions with a minimum surveillance period of 12 weeks. Evidence was synthesized as odds ratios (OR) for LEMSI occurrence between individuals assigned to interventions and those assigned to standard activities. Risk of bias was assessed with the Cochrane Risk of Bias tool 2.0. Random-effects meta-analyses were conducted for (a) physical training and (b) footwear modifications to reduce LEMSI and (c) footwear modifications to reduce stress fractures specifically. Certainty in the body of evidence was determined with the GRADE approach. Of 28,499 records, 18 trials comprised of more than 11,000 subjects were synthesized. Interventions included physical training (8, N = 6,838), footwear modifications (8, N = 3,792), nutritional supplementation (1, N = 324), and training modifications (1, N = 350). Overall risk of bias was generally moderate ( N = 7 of 18) or high ( N = 9 of 18). Physical training (OR = 0.87, 95% CI [0.71, 1.08], p = 0.22, I 2 = 58.4%) and footwear modification (OR = 1.13, 95% CI [0.85, 1.49], p = 0.42, I 2 = 0.0%) did not reduce LEMSI or stress fractures (OR = 0.76, 95% CI [0.45, 1.28], p = 0.30, I 2 = 70.7%). Our results indicate that there is weak evidence to support current LEMSI prevention strategies. Future efforts will benefit from longer surveillance periods, assessment of women and nonmilitary populations, improved methodological rigor, and a greater breadth of approaches.

Resistance exercise differentially alters extracellular vesicle size and subpopulation characteristics in healthy men and women: an observational cohort study.

Extracellular vesicles (EVs) are established mediators of adaptation to exercise. Currently, there are no published data comparing changes in EVs between men and women after resistance exercise. We tested the hypothesis that EV profiles would demonstrate a sex-specific signature following resistance exercise. Ten men and 10 women completed an acute heavy resistance exercise test for back squats using 75% of their one-repetition maximum. Blood was drawn before and immediately after exercise. EVs were isolated from plasma using size exclusion chromatography and stained with antibodies associated with exosomes (CD63), microvesicles (VAMP3), apoptotic bodies (THSD1), and a marker for skeletal muscle EVs (SGCA). CD63+ EV concentration and proportion of total EVs increased 23% (P = 0.006) and 113% (P = 0.005) in both sexes. EV mean size declined in men (P = 0.020), but not in women, suggesting a relative increase in small EVs in men. VAMP3+ EV concentration and proportion of total EVs increased by 93% (P = 0.025) and 61% (P = 0.030) in men and women, respectively. SGCA+ EV concentration was 69% higher in women compared with men independent of time (P = 0.007). Differences were also observed for CD63, VAMP3, and SGCA median fluorescence intensity, suggesting altered surface protein density according to sex and time. There were no significant effects of time or sex on THSD1+ EVs or fluorescence intensity. EV profiles, particularly among exosome-associated and muscle-derived EVs, exhibit sex-specific differences in response to resistance exercise which should be further studied to understand their relationship to training adaptations.

Effects of Multi-ingredient Preworkout Supplements on Physical Performance, Cognitive Performance, Mood State, and Hormone Concentrations in Recreationally Active Men and Women.

ABSTRACT: Beckner, ME, Pihoker, AA, Darnell, ME, Beals, K, Lovalekar, M, Proessl, F, Flanagan, SD, Arciero, PJ, Nindl, BC, and Martin, BJ. Effects of multi-ingredient preworkout supplements on physical performance, cognitive performance, mood state, and hormone concentrations in recreationally active men and women. J Strength Cond Res 36(9): 2493-2501, 2022-Performance enhancement supplement research has primarily focused on the effectiveness of individual ingredients, rather than the combination. This study investigated the acute effects of 2 multi-ingredient preworkout supplements (MIPS), with beta-alanine and caffeine (BAC) and without (NBAC), compared with placebo (PLA) on anaerobic performance, endurance capacity, mood state, cognitive function, vascular function, and anabolic hormones. Thirty exercise-trained individuals (24.4 ± 4.9 years, 15 men and 15 women) completed a fatiguing exercise protocol on 3 separate occasions, 30 minutes after ingestion of BAC, NBAC, or PLA. Outcomes were analyzed using one-way or two-way repeated-measures analysis of variance, as appropriate (alpha = 0.05). Anaerobic power was greater when supplementing with NBAC (10.7 ± 1.2 W·kg -1 ) and BAC (10.8 ± 1.4 W·kg -1 ) compared with PLA (10.4 ± 1.2 W·kg -1 ) ( p = 0.014 and p = 0.022, respectively). BAC improved V̇ o2 peak time to exhaustion ( p = 0.006), accompanied by an increase in blood lactate accumulation ( p < 0.001), compared with PLA. Both NBAC and BAC demonstrated improved brachial artery diameter after workout ( p = 0.041 and p = 0.005, respectively), but PLA did not. L-arginine concentrations increased from baseline to postsupplement consumption of BAC ( p = 0.017). Reaction time significantly decreased after exercise for all supplements. There was no effect of supplement on mood states. Exercise-trained individuals looking to achieve modest improvements in power and endurance may benefit from consuming MIPS before exercise.

Tethered Swimming Test: Reliability and the Association With Swimming Performance and Land-Based Anaerobic Performance.

ABSTRACT: Nagle Zera, J, Nagle, EF, Nagai, T, Lovalekar, M, Abt, JP, and Lephart, SM. Tethered swimming test: reliability and the association with swimming performance and land-based anaerobic performance. J Strength Cond Res 35(1): 212-220, 2021-The purpose of this study was 3-fold: (a) to examine the test-retest reliability of a 30-second maximal tethered freestyle swimming test (TST), (b) to assess the validity of the TST by examining the association with sprint swimming performance, and (c) to examine the associations between a swim-specific and land-based measure of anaerobic performance. A total of 29 male and female swimmers were recruited to participate in the study. Each subject completed a Wingate Anaerobic cycling test (WAnT), 2 or 4 TST, and a 22.9 m (25 yd), 45.7 m (50 yd), and 91.4 m (100 yd) maximal freestyle performance swims (PS). Mean and peak force (Fmean and Fpeak) were recorded for both the WAnT and TST, and average swimming velocity and time were recorded for the PS. In addition, physiological and perceptual measures were recorded immediately postexercise for all tests. The results of the present investigation showed strong intersession and intrasession reliability (R = 0.821-0.975; p < 0.001) for force parameters of the TST. Moderate correlations were found between Fmean and PS time and velocity of all distances, with slightly weaker correlations between Fpeak and the 22.9 m (time and velocity) and 45.7 m (velocity) PS. Finally, moderate correlations were found for Fmean and Fpeak of the TST and WAnT. This study demonstrated that the TST is a reliable measure, with moderate association with swimming performance, producing similar physiological responses compared with free swimming. Therefore, future research should focus on investigating the potential benefits of using the TST as a regular assessment tool as a part of a competitive swimming training program to track adaptations and inform training decisions.

Increases in Load Carriage Magnitude and Forced Marching Change Lower-Extremity Coordination in Physically Active, Recruit-Aged Women.

The objective was to examine the interactive effects of load magnitude and locomotion pattern on lower-extremity joint angles and intralimb coordination in recruit-aged women. Twelve women walked, ran, and forced marched at body weight and with loads of +25%, and +45% of body weight on an instrumented treadmill with infrared cameras. Joint angles were assessed in the sagittal plane. Intralimb coordination of the thigh-shank and shank-foot couple was assessed with continuous relative phase. Mean absolute relative phase (entire stride) and deviation phase (stance phase) were calculated from continuous relative phase. At heel strike, forced marching exhibited greater (P < .001) hip flexion, knee extension, and ankle plantar flexion compared with running. At mid-stance, knee flexion (P = .007) and ankle dorsiflexion (P = .04) increased with increased load magnitude for all locomotion patterns. Forced marching (P = .009) demonstrated a "stiff-legged" locomotion pattern compared with running, evidenced by the more in-phase mean absolute relative phase values. Running (P = .03) and walking (P = .003) had greater deviation phase than forced marching. Deviation phase increased for running (P = .03) and walking (P < .001) with increased load magnitude but not for forced marching. With loads of >25% of body weight, forced marching may increase risk of injury due to inhibited energy attenuation up the kinetic chain and lack of variability to disperse force across different supportive structures.

Utility of a novel perceptual-motor control test for identification of sport-related concussion beyond current clinical assessments.

Clinically feasible metrics, that can inform the concussion recovery decision making process by evaluating a unique domain beyond current testing domains (e.g., balance, neurocognition, symptoms, vestibular/ocular function) are still in need. The purpose of this study was to compare perceptual-motor control in adolescent athletes ≤21 days of sport-related concussion and healthy controls and evaluate the association of perceptual-motor control to the outcomes of commonly-used sport-related concussion clinical assessments. Athletes (age: 12-18 years) with sport-related concussion (n = 48) and healthy controls (n = 24) completed the Perception-Action Coupling Task (PACT), whose outcomes are mean reaction, movement, initiation, response time, and accuracy. ImPACT outcomes are verbal/visual memory scores, motor processing speed, and reaction time. Vestibular-Ocular Motor Screen (VOMS) outcomes are symptoms from: smooth pursuit, horizontal/vertical saccades, near-point of convergence, horizontal/vestibular ocular-reflex, and visual motion sensitivity. CONCUSSED demonstrated ~5% deficit in overall perceptual-motor accuracy during PACT compared to CONTROLS (p = 0.03). PACT accuracy negatively correlated with smooth pursuits(r = -0.29), and horizontal (r = -0.35)/vertical (r = -0.30) saccades. The C5.0 decision tree determined PACT accuracy was the most relevant predictor of sport-related concussion when no visual motion sensitivity symptoms were reported and Visual Memory was >66. Perceptual-motor control tests may complement current sport-related concussion assessments when neurocognition and vestibular/ocular motor system are not grossly impaired.

Compromised Dynamic Postural Stability Under Increased Load Carriage Magnitudes.

Warfighter performance may be compromised through the impact of load carriage on dynamic postural stability. Men and women may experience this impact to differing extents due to postural stability differences. Therefore, the authors investigated the effect of load magnitude on dynamic postural stability in men and women during a landing and stabilization task. Dynamic postural stability of 32 subjects (16 women) was assessed during the unilateral landing of submaximal jumps under 3 load conditions: +0%, +20%, and +30% body weight. Dynamic postural stability was measured using the dynamic postural stability index, which is calculated from ground reaction force data sampled at 1200 Hz. Two-way mixed-measures analysis of variance compared dynamic postural stability index scores between sexes and loads. Dynamic postural stability index scores were significantly affected by load (P = .001) but not by sex or by the sex by load interaction (P > .05). Dynamic postural stability index scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034), and 30% (0.420 ± 0.028) body weight conditions. Increased load negatively affects dynamic postural stability with similar performance decrements displayed by men and women. Men and women warfighters may experience similar performance decrements under load carriage conditions of similar relative magnitudes.

Energy Deficiency During Cold Weather Mountain Training in NSW SEAL Qualification Students.

Special operation forces participating in mountain warfare/cold weather (MWCW) training have higher energy demands, but adequate fueling is difficult to achieve. The purpose of the study was to determine energy expenditure relative to energy intake and examine fueling patterns during 3 days of MWCW training in Naval Special Warfare Sea, Air, Land (SEAL) Qualification Training (SQT) students. Ten SQT students (age: 23.3 ± 1.8 years, height: 182.3 ± 6.4 cm, and weight: 83.6 ± 4.5 kg) were fitted for heart rate and accelerometer monitors during MWCW training. Total daily energy expenditure was determined using a combination of direct observation and heart rate-VO2 regression. Total daily energy intake was collected using the Automated Self-Administered 24 (ASA24) assessment tool. Total daily energy expenditure for river crossing, alpine skills, and mountain patrol were 3,913 ± 293, 4,207 ± 400, and 5,457 ± 828 kcals, respectively. Reported total daily energy intakes were 2,854 ± 657 (river crossing) and 2,289 ± 680 kcals (mountain patrol), producing 1,044 ± 784 and 3,112 ± 1,420 kcal deficits, respectively. SQT students consumed 258 ± 95 g (3.1 ± 1.3 g·kg-1·day-1) of carbohydrates, 130 ± 55 g (1.6 ± 0.7 g·kg-1·day-1) of protein, and 113 ± 39 g (1.4 ± 0.5 g·kg-1·day-1) of fat. MWCW training evolutions elicited high total daily energy expenditure and inadequate energy intake, especially before and during active training sessions, which may lead to decreased work output, early onset fatigue, and increased risk of injury. Increasing total daily energy intake by providing fuel/fluids, primarily carbohydrates, during the planned breaks and "downtime" of each training evolution and focusing on provision of the balance of calories/macronutrients needed for a more complete and expedited recovery over dinner and evening snacks will help bridge the energy gap.

Reliability and Validity of a Pool-Based Maximal Oxygen Uptake Test to Examine High-Intensity Short-Duration Freestyle Swimming Performance.

Nagle, EF, Nagai, T, Beethe, AZ, Lovalekar, MT, Zera, JN, Connaboy, C, Abt, JP, Beals, K, Nindl, BC, Robertson, RJ, and Lephart, SM. Reliability and validity of a pool-based maximal oxygen uptake test to examine high-intensity short-duration freestyle swimming performance. J Strength Cond Res 33(5): 1208-1215, 2019-A modality-specific swimming protocol to assess maximal oxygen uptake (V[Combining Dot Above]O2maxsw) is essential to accurately prescribe and monitor swimming conditioning programs. Consequently, there is a need for a reliable and valid graded intensity swimming pool test to accurately assess V[Combining Dot Above]O2maxsw using indirect calorimetry. The purpose of this study was to assess (a) reliability of an intensity self-regulated swimming pool test of V[Combining Dot Above]O2maxsw and (b) validity of a V[Combining Dot Above]O2maxsw test using performance swim (PS) time as the criterion. Twenty-nine men (n = 15) and women (n = 14) (age, 23 ± 6.4 years; body mass index, 23.5 ± 3.0 kg·m) performed 2 swimming pool V[Combining Dot Above]O2maxsw trials (V[Combining Dot Above]O2maxsw A and V[Combining Dot Above]O2maxsw B), and 2 PS tests (45.7 m [31.20 ± 4.5 seconds] and 182 m [159.2 ± 25.5 seconds]). For test-retest reliability (trials A vs. B), strong correlations (p < 0.05) were found for V[Combining Dot Above]O2maxsw (ml·kg·min) (r = 0.899), O2 pulse (ml O2·beat) (r = 0.833), and maximum expired ventilatory volume (L·min) (r = 0.785). For performance validity, moderately strong correlations (p < 0.05) were found between V[Combining Dot Above]O2maxsw A and 45.7-m (r = -0.543) and 182-m (r = -0.486) swim times. The self-regulated graded intensity swimming pool protocol examined presently is a reliable and valid test of V[Combining Dot Above]O2maxsw. Studies should consider the suitability of a V[Combining Dot Above]O2maxsw test for military personnel, clinical populations, and injured athletes.

Physical Fitness Predictors of a Warrior Task Simulation Test.

Huang, H-C, Nagai, T, Lovalekar, M, Connaboy, C, and Nindl, BC. Physical fitness predictors of a warrior task simulation test. J Strength Cond Res 32(9): 2562-2568, 2018-The warrior task simulation test (WTST) has been developed in an attempt to better assess physical fitness required for soldiers to perform battlefield tasks and drills to determine whether laboratory-based measurements of physical fitness components could be used to predict the WTST. Forty-three healthy and physically active men participated in 2 sessions: the WTST and laboratory testing. The WTST comprised 282-m run, low hurdles, high crawl, casualty drag, balance beam, point-aim-move, 100-yard sprint, and agility sprint with participants wearing combat boots, uniform, helmet, and dummy rifle. The laboratory testing included assessments of participants' muscular strength and endurance, postural stability, aerobic capacity, anaerobic capacity, flexibility, body fat, fat-free mass, and agility. Correlation and simple and multiple linear regression analyses were used to analyze the relationship between the WTST and laboratory testing and predict the WTST, respectively (p < 0.05). The correlation and the simple linear regression analyses revealed that anaerobic capability, aerobic capacity, body fat, agility, and muscular endurance correlated with (r = 0.35-0.59) and accounted for 12-34% of the variance in (R = 0.12-0.34) the WTST performance (p < 0.05). The final model included aerobic capacity, agility, fat-free mass, muscular endurance, and body fat (R = 0.52, p < 0.001). The current results highlighted the importance of several components of physical fitness in simulated battlefield tasks and drills (assessed by the WTST). In particular, anaerobic capacity, aerobic capacity, and body fat had the highest correlational and predictive values of the WTST. Additionally, skill-related components of physical fitness, such as agility and muscular endurance, should not be ignored, and they should be assessed and tracked with the above-mentioned components.

The Relationship of Core Strength and Activation and Performance on Three Functional Movement Screens.

Johnson, CD, Whitehead, PN, Pletcher, ER, Faherty, MS, Lovalekar, MT, Eagle, SR, and Keenan, KA. The relationship of core strength and activation and performance on three functional movement screens. J Strength Cond Res 32(4): 1166-1173, 2018-Current measures of core stability used by clinicians and researchers suffer from several shortcomings. Three functional movement screens appear, at face-value, to be dependent on the ability to activate and control core musculature. These 3 screens may present a viable alternative to current measures of core stability. Thirty-nine subjects completed a deep squat, trunk stability push-up, and rotary stability screen. Scores on the 3 screens were summed to calculate a composite score (COMP). During the screens, muscle activity was collected to determine the length of time that the bilateral erector spinae, rectus abdominis, external oblique, and gluteus medius muscles were active. Strength was assessed for core muscles (trunk flexion and extension, trunk rotation, and hip abduction and adduction) and accessory muscles (knee flexion and extension and pectoralis major). Two ordinal logistic regression equations were calculated with COMP as the outcome variable, and: (a) core strength and accessory strength, (b) only core strength. The first model was significant in predicting COMP (p = 0.004) (Pearson's Chi-Square = 149.132, p = 0.435; Nagelkerke's R-Squared = 0.369). The second model was significant in predicting COMP (p = 0.001) (Pearson's Chi-Square = 148.837, p = 0.488; Nagelkerke's R-Squared = 0.362). The core muscles were found to be active for most screens, with percentages of "time active" for each muscle ranging from 54-86%. In conclusion, performance on the 3 screens is predicted by core strength, even when accounting for "accessory" strength variables. Furthermore, it seems the screens elicit wide-ranging activation of core muscles. Although more investigation is needed, these screens, collectively, seem to be a good assessment of core strength.

Gender Differences in Static and Dynamic Postural Stability of Soldiers in the Army's 101st Airborne Division (Air Assault).

CONTEXT: Postural stability is essential for injury prevention and performance. Differences between genders may affect training focus. OBJECTIVE: To examine static and dynamic postural stability in male and female soldiers. DESIGN: Descriptive laboratory study. SETTING: Biomechanics laboratory. PARTICIPANTS: 25 healthy female soldiers (26.4 ± 5.3 y) and 25 healthy male soldiers (26.4 ± 4.9 y) matched on physical demand rating and years of service from the Army's 101st Airborne Division (Air Assault). INTERVENTIONS: Each person underwent static and dynamic postural stability testing. MAIN OUTCOME MEASURES: Standard deviation of the ground reaction forces during static postural stability and the dynamic stability index for dynamic postural stability. RESULTS: Female soldiers had significantly better static postural stability than males but no differences were observed in dynamic postural stability. CONCLUSIONS: Postural stability is important for injury prevention, performance optimization, and tactical training. The differences observed in the current study may indicate the need for gender-specific training emphasis on postural stability.

Block-Periodized Training Improves Physiological and Tactically Relevant Performance in Naval Special Warfare Operators.

Human performance training and prevention strategies are necessary to promote physical readiness and mitigate musculoskeletal injuries of the Naval Special Warfare (NSW) Operator. The purpose of this study was to measure the effectiveness of 2 training programs when performed during a training evolution of Operators. A total of 85 Operators (experimental: n = 46, age: 29.4 ± 5.5 years, height: 176.7 ± 6.4 cm, mass: 86.7 ± 11.6 kg; control: n = 39, age: 29.0 ± 6.0 years, height: 177.1 ± 6.3 cm, mass: 85.7 ± 12.5 kg) participated in a trial to measure the effectiveness of these programs to improve physical, physiological, and performance characteristics. Operators in the experimental group performed a 12-week block-periodized program, whereas those in the control group performed a nonlinear periodized program. Pretesting/posttesting was performed to assess body composition, aerobic capacity/lactate threshold, muscular strength, flexibility, landing biomechanics, postural stability, and tactically relevant performance. The experimental group demonstrated a significant loss in body fat, fat mass, and body mass compared with the control group, whereas aerobic capacity increased for the both groups. The experimental group demonstrated a significant increase in posterior shoulder flexibility and ankle dorsiflexion, whereas the control group had a significant reduction in shoulder, knee, and ankle flexibility. The experimental group also improved landing strategies and balance. Both groups improved upper and lower muscular power and upper-body muscular endurance, whereas only the experimental group demonstrated significant improvements in agility and total body muscular strength. Implementation of a population-specific training program provides structured and progressive training effectively and promotes physical readiness concurrently with tactical training without overload.

Energy Drinks Improve Five-Kilometer Running Performance in Recreational Endurance Runners.

Prins, PJ, Goss, FL, Nagle, EF, Beals, K, Robertson, RJ, Lovalekar, MT, and Welton, GL. Energy drinks improve five-kilometer running performance in recreational endurance runners. J Strength Cond Res 30(11): 2979-2990, 2016-The purpose of this study was to evaluate exercise performance time and related physiological and perceptual responses of recreational endurance runners after they had ingested a commercially available energy drink (Red Bull, Red Bull GmbH, Fuschl am See, Austria) containing caffeine, glucose, and taurine. Recreational endurance runners (n = 18; 13 men and 5 women; age: 20.39 ± 3.27 years; weight: 71.25 ± 17.17 kg; height: 178.00 ± 7.57 cm; V[Combining Dot Above]O2max: 55.94 ± 7.66 ml·kg·min) participated in a double-blind, crossover, repeated-measures study where they were randomized to supplement with 500 ml of the commercially available energy drink Red Bull and a noncaffeinated, sugar-free placebo (PLA) 60 minutes before completing a 5-km time trial on a treadmill, separated by 7 days. Heart rate, rating of perceived exertion (RPE) (RPE-Overall; RPE-Chest; RPE-Legs), and affect were recorded at rest, 1 hour before ingestion, at 5-minute intervals during the 5-km time trial, and immediately after exercise. Session RPE and session affect were obtained 5 minutes after completion of the 5-km time trial. The distance covered at each 5-minute interval during the 5-km time trial was recorded. Performance improved with the energy drink compared with placebo (Red Bull: 1,413.2 ± 169.7 vs. PLA: 1,443.6 ± 179.2 seconds; p = 0.016), but there were no differences in RPE, affect, session RPE, session affect, or the distance covered at 5-minute splits between the two 5-km time trials (p > 0.05). These results demonstrate that consuming a commercially available energy drink before exercise can improve 5-km performance. These results may have application for altering pre-exercise nutritional strategies in recreational runners.

Reliability and validity of instrumented soccer equipment.

Ankle ligament sprains are the most common injury in soccer. The high rate of these injuries demonstrates a need for novel data collection methodologies. Therefore, soccer shoes and shin guards were instrumented with inertial sensors to measure ankle joint kinematics in the field. The purpose of this study was to assess test-retest reliability and concurrent criterion validity of a kinematic assessment using the instrumented soccer equipment. Twelve soccer athletes performed athletic maneuvers in the laboratory and field during 2 sessions. In the laboratory, ankle joint kinematics were simultaneously measured with the instrumented equipment and a conventional motion analysis system. Reliability was assessed using ICC and validity was assessed using correlation coefficients and RMSE. While our design criteria of good test-retest reliability was not supported (ICC > .80), sagittal plane ICCs were mostly fair to good and similar to motion analysis results; and sagittal plane data were valid (r = .90-98; RMSE < 5°). Frontal and transverse plane data were not valid (r < .562; RMSE > 3°). Our results indicate that the instrumented soccer equipment can be used to measure sagittal plane ankle joint kinematics. Biomechanical studies support the utility of sagittal plane measures for lower extremity injury prevention.

Recruit Profiles Across the U.S. Armed Forces: Implications for Increasing Gender Integration in Recruit Training.

INTRODUCTION: This article uses recent survey data from a study on gender integration at recruit training across the U.S. Armed Forces to examine service, gender, and training differences in recruit's gender attitudes, beliefs, and cohesion metrics. In addition to providing a descriptive understanding of our recruit sample, this article examines factors germane to gender integration at recruit training such as gender attitudes, sexist beliefs, and unit cohesion. MATERIALS AND METHODS: This article uses data from a survey of U.S. Marine Corps (USMC), U.S. Army, U.S. Air Force, U.S. Navy, and U.S. Coast Guard recruits as part of a USMC-commissioned study to develop alternate models and recommendations for increasing gender integration in USMC recruit training. At all sites but the USMC, recruits completed the survey 1 to 2 weeks before graduation. At the Marine Corps Recruit Depots, recruits participated in the survey at the beginning (week 2) and end (week 11) of their 13-week training cycle. A 19-question survey captured sociodemographic information, perspectives and experiences during recruit training, and gender attitudes and beliefs. Analyses were conducted on the sample with complete data on the measures reported, including those USMC recruits observed at both week 2 and week 11 (n = 629). Descriptive statistics (percentage) were calculated for all categorical outcome variables. Outcome variables (cohesion, gender, and sexism attitudes) were compared between groups using chi-squared tests or Fisher's exact tests, as appropriate. RESULTS: Recruits differed significantly across services in perceptions of unit cohesion on 3 of the 4 indicators: Platoon members are cooperative, know they can depend on each other, and really respect each other (P < .05). These differences appear to be driven by female recruit difference across service. They reported significant differences in gender role attitudes across the services, with USMC recruits being most likely to endorse traditional gender roles compared to other service recruits. Male USMC recruits were significantly more likely than their female peers to agree that men should achieve outside the home and women should take care of the home and family (21.3% versus 6.3%, P < .05). The only statistical differences in attitudes about equality of treatment and opportunity among recruits were between male and female USMC recruits. All items capturing sexist attitudes elicited statistically significant differences between male USMC recruits and male recruits in other services (P < .05). There were significant differences in all sexism measures between male and female USMC recruits (P < .05). There is a significant decline in some sexist attitudes between weeks 2 and 11 of training among male USMC recruits (P < .05). Nearly one-half to three-fourths of male USMC recruits hold sexist attitudes, even near the end of recruit training. CONCLUSIONS: The disparate gender and sexism attitudes of male USMC recruits compared with their peers in other services, and their fellow female USMC recruits suggest efforts to increase gender integration at entry-level training are needed, but also may be challenging since male USMC recruits report the highest levels of sexist attitudes among all recruits.

Recruit Perspectives on Gender Integration at Recruit Training: A Comparison by Service and Gender.

INTRODUCTION: Recruit training is the initial entry for enlisted personnel in the military. The Services execute gender-integrated recruit training differently. The U.S. Marine Corps (USMC) maintains same-gender platoons led by same-gender drill instructors in integrated companies; further integration occurs at select training events. The other Services train recruits in gender-integrated units with mixed-gender drill instructor teams. We examine recruits' experiences and perceptions of gender integration at recruit training, their desired level of integration, and preferences for increasing gender integration, comparing by Service and gender. MATERIALS AND METHODS: Recruit perspectives and experiences were captured in a 19-question survey (n = 632) and 90-min focus groups (n = 260) near graduation from recruit training. Data were collected from June to November 2021. Because of the Coronavirus disease (COVID-19) pandemic restrictions, the Navy and Air Force were not conducting gender-integrated recruit training during data collection. Outcome variables were compared cross-Service by gender and within Service by gender using chi-squared tests or Fisher's exact tests, as appropriate; focus group data were analyzed using initial and secondary coding schemes. Three USMC training models, varied by level of integration, were also analyzed (Male-Only, Series Track, and Integrated Company). RESULTS: Significant gender differences across and within Service emerged in recruits' experience being trained by an opposite-gender instructor. Male recruits had significant differences by Service (P < .001), and USMC female recruits reported being trained by male instructors more than their male peers by female instructors (Series Track P = .002; Integrated Company P < .001). In the focus groups, recruits described common differences with how men and women embodied being a drill instructor. Significant gender differences across (both male and female P < .001) and within Service were reported for closeness of training with opposite-gender peers (Air Force P = .028; U.S. Marine Corps (USMC) Integrated Company P = .010; Army P = .048), an expected finding given varied integration during data collection. Male and female recruits had significant differences by Service in their preference for integration at the lowest unit level (both male and female P < .001), with those who experienced integrated training showing higher levels of endorsement. In the focus groups, recruits articulated benefits and challenges of gender-integrated recruit training. Significant gender differences across Service emerged in preferences for more integration in specific training activities. Within Service, female USMC Integrated Company recruits wanted more integration in tactical/field, physical fitness, and classroom training than their male peers (P < .001 for all). In the focus groups, USMC recruits of both genders desired more integrated training events, particularly those involving combat and tactical skill development. CONCLUSIONS: This study provided an opportunity to examine recruit perspectives on gender-integrated training. Services valuing opposite-gender instructor exposure in recruit training must ensure that male recruits are being taught and led by female instructors given disproportionate demographics. Recruits who experienced integrated training were more supportive of integration, indicating that this experience may increase their support for gender-integrated training units and environments. Today's recruits understand that they are entering gender-integrated working environments, and our results indicate that they expect recruit training to mirror that reality.