Relationships of Lower-body Power Measures to Sprint and Change of Direction Speed among NCAA Division II Women's Lacrosse Players: An Exploratory Study

This study sought to determine if significant relationships exist between lower-body power measures to sprint and change of direction speed (CODS) in Division II collegiate women's lacrosse athletes. Archived data for 17 NCAA Division II female lacrosse athletes was provided to the investigators for analysis. Jumping performance was assessed using a countermovement jump (CMJ), squat jump (SJ), and standing broad jump (SBJ). Sprint speed was measured at 10m and 30m, of a 30m sprint. CODS was evaluated using a T-Test (TT), a modified T-Test (MTT), and the 5-0-5 Agility Test (5-0-5). No significant relationships were found between absolute power measures and any sprint or CODS tests. However, relative power (relative CMJ and SJ) had significant relationships with all CODS and sprints speeds above 10m. Only the CMJ and relative CMJ were related to 10m sprint speed. SBJ distance had significant relationships with all CODS tests and 30m speed, while relative SBJ distance significantly correlated with 5-0-5 speed. Relative lower-body power was significantly related to speed and CODS in Division II female lacrosse athletes. Strength and conditioning professionals should focus on lower-body power development as a key component in preparing female lacrosse athletes for their sport.

The Impact of Formal Strength and Conditioning on the Fitness of Law Enforcement Recruits: A Retrospective Cohort Study

Research involving law enforcement populations has suggested better fitness could enhance job task performance and reduce injuries. Academy training should lead to improvements in recruit fitness. The aim of this study was to investigate the impact of a strength and conditioning program on fitness among law enforcement recruits. Twenty-six recruits (23 males, three females) completed a 27-week academy, which incorporated 3-4 physical training sessions per week. Fitness assessment occurred during pre- (week 0), mid- (week 14), and post-testing (week 27) time points. The fitness assessments included: vertical jump, one-minute push-ups, one-minute sit-ups, posterior chain strength measured by a leg/back dynamometer, grip strength, and aerobic fitness measured by the 20-m multistage shuttle run (MSR). A repeated measures ANOVA with Bonferroni post hoc tests determined any significant changes in fitness between time points, with alpha set at p < .05. Due to the small sample size of females, statistical analysis was only conducted on male recruits. Overall, significant main effects (p < .001) were observed in all fitness assessments except for grip strength. The results detailed general improvements in fitness. However, push-up and MSR scores decreased from mid- to post-test, while sit-ups did not change. Posterior chain strength and the vertical jump improved from mid-to post-test. The data indicated that the strength and conditioning program positively influenced the fitness of recruits. An increased focus on skill-specific work in the second-half of academy may have contributed to the plateaus in muscular endurance and aerobic fitness, and improvement of lower-body strength and power.

Association Between Knee- and Hip-Extensor Strength and Running-Related Injury Biomechanics in Collegiate Distance Runners

CONTEXT

Running-related injuries are common in distance runners. Strength training is used for performance enhancement and injury prevention. However, the association between maximal strength and distance-running biomechanics is unclear.

OBJECTIVE

To determine the relationship between maximal knee- and hip-extensor strength and running biomechanics previously associated with injury risk.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 36 collegiate distance runners (26 men, 10 women; age = 20.0 ± 1.5 years, height = 1.74 ± 0.09 m, mass = 61.97 ± 8.26 kg).

MAIN OUTCOME MEASURE(S)

Strength was assessed using the 1-repetition maximum (1RM) back squat and maximal voluntary isometric contractions of the knee extensors and hip extensors. Three-dimensional running biomechanics were assessed overground at a self-selected speed. Running variables were the peak instantaneous vertical loading rate; peak forward trunk-lean angle; knee-flexion, internal-rotation, and -abduction angles and internal moments; and hip-extension, internal-rotation, and -adduction angles and internal moments. Separate stepwise linear regression models were used to examine the associations between strength and biomechanical outcomes (ΔR2) after accounting for sex, running speed, and foot-strike index.

RESULTS

Greater 1RM back-squat strength was associated with a larger peak knee-flexion angle (ΔR2 = 0.110, ΔP = .045) and smaller peak knee internal-rotation angle (ΔR2 = 0.127, ΔP = .03) and internal-rotation moment (ΔR2 = 0.129, ΔP = .03) after accounting for sex, speed, and foot-strike index. No associations were found between 1RM back-squat strength and vertical loading rate, trunk lean, or hip kinematics and kinetics. Hip- and knee-extensor maximal voluntary isometric contractions were also not associated with any biomechanical variables.

CONCLUSIONS

Greater 1RM back-squat strength was weakly associated with a larger peak knee-flexion angle and smaller knee internal-rotation angle and moment in collegiate distance runners. Runners who are weaker in the back-squat exercise may exhibit running biomechanics associated with the development of knee-related injuries.

Waist Circumference and Waist-to-Hip Ratio in Law Enforcement Agency Recruits: Relationship to Performance in Physical Fitness Tests

Lockie, RG, Ruvalcaba, TR, Stierli, M, Dulla, JM, Dawes, JJ, and Orr, RM. Waist circumference and waist-to-hip ratio in law enforcement agency recruits: relationship to performance in physical fitness tests. J Strength Cond Res 34(6): 1666-1675, 2020-Law enforcement agencies (LEAs) use tests to assess recruit physical fitness. Body fat can influence test performance but is difficult to measure during academy because of time, equipment constraints, and instructor knowledge. This study examined relationships between waist circumference (WC) and waist-to-hip ratio (WHR), practical measures of fat distribution, and fitness test performance. Retrospective analysis of 267 LEA recruits (age: ∼28 years; height: ∼1.73 m; and body mass: ∼80 kg; 219 males and 48 females) was conducted. The tests included: WC and WHR; grip strength; push-ups, sit-ups, and arm ergometer revolutions in 60 seconds; vertical jump (VJ); medicine ball throw; 75-yd pursuit run (75PR); and multistage fitness test (MSFT) shuttles. Partial correlations, controlling for sex, calculated relationships between WC, WHR, and the fitness tests. Recruits were split into quartile groups (based on the sample size) for WC and WHR (group 1 had the lowest WC and WHR; and group 4 the highest). A 1-way multivariate analysis of variance, with sex as a covariate and Bonferroni post hoc, compared between-group test performance. A greater WC related to lesser push-up, sit-up, VJ, 75PR, and MSFT performance (p ≤ 0.024). When recruits were split into WC groups, group 4 had lesser performance in push-ups, sit-ups, VJ, and the 75PR compared with all groups (p ≤ 0.038). When split into WHR groups, group 4 performed less push-ups than group 1, less MSFT shuttles than group 3, and had a lower VJ compared with all groups (p ≤ 0.042). Recruits with a greater WC tended to have poorer fitness test performance.

The Influence of Aerobic Fitness on Heart Rate Responses of Custody Assistant Recruits during Circuit Training Sessions

This study captured heart rate (HR) responses of custody assistant (CA) recruits undertaking circuit training sessions. Data from 10 male and 12 female CA recruits were analyzed. Based on YMCA step test recovery HR, recruits were divided into higher fitness (HF; top 25%), lower fitness (LF; bottom 25%), and moderate fitness (MF; remaining recruits) groups. HR was measured during two circuit training sessions featuring calisthenics and running. HR zones were defined as: very light (<57% of age-predicted maximum heart-rate [HRmax]); light (57-63% HRmax); moderate (64-76% HRmax); vigorous (77-95% HRmax); and very vigorous (>95% HRmax). A one-way ANOVA, with Bonferroni post hoc, calculated between-group differences in time spent, and percentage of total time, in the HR zones. In session one, the LF group spent less time in the light training zone compared to the MF group, and more time in the very vigorous zone compared to the HF group (p = 0.027-0.047). In session two, the LF group spent more time in the moderate zone compared to both groups, and a greater percentage of time in the very vigorous zone compared to the MF group (p = 0.002-0.004). LF recruits generally worked harder during circuit training than their fitter counterparts, which supported recommendations for ability-based modifications.

Perceived and Measured Physical Fitness of Police Students

The physical fitness of police officers needs to support good health and physical performance. Physical fitness comprises a considerable amount of training for police students who are to become police officers. However, to what degree police students are able to perceive their fitness level and differentiate between health-related and performance-related physical fitness is unknown. Therefore, the first aim of this study was to investigate the possibility of differentiation between health-related and performance-related physical fitness using physical self-concept and measured indicators of physical fitness. The second aim of this study was to investigate the association between components of physical self-concept and measured indicators of physical fitness of police students. The sample of 177 police students of both sexes (98 males and 79 females) completed a 40-item physical self-description questionnaire and their physical abilities were assessed for handgrip strength, standing long jump, 30 s sit-ups, and 12-min running. Principal component analysis established health-related and performance-related physical fitness from both perceived and measured physical fitness measures. Correlation analysis revealed a significant relationship between the perceived and measured physical fitness. Results suggest small to moderate ability to recognize the level of certain physical abilities, indicating the association between psychological mechanisms and biological functioning.

Physical Fitness, Sex Considerations, and Academy Graduation for Law Enforcement Recruits

Lockie, RG, Dawes, JJ, Dulla, JM, Orr, RM, and Hernandez, E. Physical fitness, sex considerations, and academy graduation for law enforcement recruits. J Strength Cond Res 34(12): 3356-3363, 2020-This study investigated the influence of fitness on academy graduation, and any between-sex differences, in law enforcement recruits. Data collected at the start of 4 training academies were retrospectively analyzed, including age, height, and body mass; waist circumference; waist-to-hip ratio; grip strength; vertical jump (VJ); 75-yard pursuit run; 2-kg medicine ball throw (MBT); push-ups, sit-ups, and arm ergometer revolutions in 60 seconds; and 20-m multistage fitness test (20MSFT) shuttles. Recruits were categorized into graduated (GRAD = 269) and separated (did not graduate; SEP = 42) groups. SEP recruits were not split according to separation reasons, just whether they did or not. This categorization also occurred for male subjects (GRAD = 228; SEP = 32) and female subjects (GRAD = 41; SEP = 10). Independent samples t-tests calculated between-group differences for all recruits combined, male subjects, and female subjects. Correlations and stepwise linear regression calculated relationships between the data and graduation. The t-test (p ≤ 0.016) and correlation (r = ±0.137-0.296; p < 0.05) data indicated that SEP recruits (both sexes combined) were older and performed poorer in every fitness test except grip strength and VJ. SEP male subjects were older and performed poorer in all tests except grip strength (p ≤ 0.009). SEP female subjects scored lower in the arm ergometer (p = 0.008). The regression equation for all recruits found that age, 20MSFT (aerobic fitness), MBT (upper-body power), and arm ergometer (upper-body endurance) were academy graduation predictors (r = 0.169; p < 0.001). For the male recruits, the predictors were age, MBT, and 20MSFT (r = 0.182; p ≤ 0.001), and for female recruits, arm ergometer and 20MSFT (r = 0.213; p ≤ 0.003). Recruits should improve multiple fitness aspects, including muscular endurance, power, and aerobic fitness, to enhance graduation potential.

Recruit Fitness Standards From a Large Law Enforcement Agency: Between-Class Comparisons, Percentile Rankings, and Implications for Physical Training

Lockie, RG, Dawes, JJ, Orr, RM, and Dulla, JM. Recruit fitness standards from a large law enforcement agency: Between-class comparisons, percentile rankings, and implications for physical training. J Strength Cond Res 34(4): 934-941, 2020-Law enforcement can be a physically demanding profession. Many agencies use a "one-size-fits-all" academy training approach, which may not be optimal for all recruits. There is also little information that benchmarks fitness of law enforcement recruits. The purpose of this study was to analyze between-academy class differences in fitness, as well as produce normative data for the development of strength and conditioning programs. A retrospective analysis of 908 recruits (761 men and 147 women), comprising 11 classes from one agency, was used. Fitness assessment data included push-ups, sit-ups, and mountain climbers in 120 seconds; pull-ups; 201-m run; and 2.4-km run. A one-way analysis of variance with a Bonferroni post hoc adjustment revealed that fitness varied significantly between classes. Class 11 completed less sit-ups than 6 other classes (p ≤ 0.033) and were slower in the 201-m and 2.4-km run than 5 classes (p ≤ 0.005). Class 7 completed less push-ups than 3 classes (p ≤ 0.036) and less mountain climbers and were slower in the 201-m run than 5 classes (p ≤ 0.005). Individual recruit analysis and percentile data indicated a wide spread of all assessment results and the effects upon female recruits. For example, 81% of women completed ≤2 pull-ups and were in the bottom 2 percentile bands; 72-76% of women were in the bottom 3 bands for push-ups and the 201-m run. Fitness varies from class-to-class, and female recruits will generally be less physically fit. Training staff should ideally implement individualized, ability-based programming where appropriate to train their recruits.

A Research Note on Relationships Between the Vertical Jump and Standing Broad Jump in Law Enforcement Recruits: Implications for Lower-Body Power Testing

Lockie, RG, Moreno, MR, and Dawes, JJ. A research note on relationships between the vertical jump and standing broad jump in law enforcement recruits: implications for lower-body power testing. J Strength Cond Res XX(X): 000-000, 2020-Jump testing is often used to infer lower-body power in law enforcement recruits. The vertical jump (VJ) is most common, but can be equipment-intensive. The standing broad jump (SBJ) also provides a measure of lower-body power, requires less equipment, and could be practical for training staff with limited resources. There has been no analysis of the relationships between the VJ and SBJ in law enforcement recruits to ensure they measure similar qualities. This research note investigated the relationships between the VJ and SBJ in recruits from one agency. The sample included 71 men and 23 women who completed the VJ and SBJ before academy. Independent samples t-tests compared the sexes in both jump tests. Pearson's correlations calculated relationships between the VJ and SBJ variables (VJ height, height relative to body mass, peak power and power-to-body mass ratio calculated from VJ height; SBJ distance and distance relative to body mass) in all recruits combined, men, and women. Male recruits outperformed females in all absolute VJ and SBJ variables (p < 0.001), except for relative-to-body mass VJ and SBJ. There were large significant relationships between most jump variables for all recruits combined, men, and women (r = 0.371-0.684). Relative VJ and SBJ did not significantly relate (r = 0.123-0.203). There were generally strong relationships between the VJ and SBJ in recruits, although the relative data indicated some differences in qualities assessed by each jump. Nonetheless, training staff could use the SBJ as a lower-body absolute power indicator, especially with limited resources.

Job-Specific Physical Fitness Changes Measured by the Work Sample Test Battery within Deputy Sheriffs between Training Academy and their First Patrol Assignment

Deputy Sheriffs need to exhibit job-specific fitness throughout their occupational lifespan. This study evaluated job-specific fitness changes measured by the Work Sample Test Battery (WSTB) in deputy sheriffs from training academy to patrol school (refresher program completed before first patrol assignment). WSTB data for 34 deputy sheriffs (28 males, 6 females) was retrospectively analyzed. The WSTB included five tests: a 99-yard obstacle course (99OC); a 165-pound body drag (BD); 6-foot chain link fence (CLF) and solid wall (SW) climbs; and a 500-yard run (500R). WSTB task times measured at the end of academy and start of patrol school were compared by paired samples t-tests, percentage change, and effect sizes (all deputy sheriffs combined and by sex). When data for all deputy sheriffs was combined, there were significant time increases for the WSTB tasks at patrol school (p ≤ 0.009; d = 0.45-1.67), except for the BD (p < 0.001; d = 0.80). Male deputy sheriffs exhibited the same changes (p ≤ 0.042, d = 0.40-2.37), with very large CLF and SW decrements (34-83%). Females experienced a significant decline in the 99OC (p = 0.013; d = 0.79), and non-significant declines in all other tasks (p ≤ 0.324; d = 0.50-0.96). Apart from the BD for male deputy sheriffs, job-specific fitness measured by the WSTB declined when deputy sheriffs went on their first patrol assignment. The ability to perform obstacle clearance (CLF, SW) and foot pursuit tasks (99OC, 500R) was particularly reduced. Intervention strategies to aid job-specific fitness maintenance is recommended for deputy sheriffs.

Postactivation Performance Enhancement of Concentric Bench Press Throw After Eccentric-Only Conditioning Exercise

Krzysztofik, M, Wilk, M, Lockie, RG, Golas, A, Zajac, A, and Bogdanis, GC. Postactivation performance enhancement of concentric bench press throw after eccentric-only conditioning exercise. J Strength Cond Res XX(X): 000-000, 2020-This study examined changes in power output and bar velocity in the concentric-only bench press throw (CONONLY) after a sets of eccentric-only bench press exercises (ECCONLY) at 2 supramaximal loads. Thirteen strength-trained men participated in this study (age = 25.7 ± 1.9 years, body mass = 94.8 ± 8 kg, 1 repetition maximum [1RM] = 147 ± 14.2 kg, and strength training experience = 6.5 ± 2.2 years). The subjects performed 2 conditioning sets of the bench press exercise of 2 repetitions each, with a 5 minutes rest interval between sets, using the ECCONLY mode against 110% or 130% of concentric 1RM load. The 1 repetition of the CONONLY bench press throw with a load of 30% 1RM was performed before and 5 minutes after the conditioning activity (CA) to assess changes in peak power (PP) and peak velocity (PV). The differences between the analyzed variables before and after the CA were determined using a 2-way repeated measures analysis of variance. There was an increase of PP by 10.5 ± 6.0% (effect size [ES] = 0.34) and 9.9 ± 8.1% (ES = 0.33) for the 110 and 130% of concentric 1RM conditions, respectively, with no difference between the 2 conditions (p < 0.01 main effect time, no interaction). Similarly, PV increased by 5.9 ± 5.5% (ES = 0.40) and 6.1 ± 6.1% (ES = 0.43) for the 110 and 130% of concentric 1RM conditions, respectively, with no difference between the 2 conditions (p < 0.01 main effect time, no interaction). Activation with an ECCONLY contraction and loads exceeding 1RM are effective at improving power output and bar velocity during the CONONLY bench press throw.

Relationships Between Isometric Strength and the 74.84-kg (165-lb) Body Drag Test in Law Enforcement Recruits

This study investigated whether: law enforcement recruits could complete a 74.84-kg (165-lb) body drag without specific training; relationships between the body drag and absolute and relative isometric grip and leg/back strength could be established to assist with training recommendations; a strength baseline needed to complete the 74.84-kg body drag could be established. Retrospective analysis on a recruit class (72 males, 21 females) from one agency was conducted. Recruits completed the body drag, and had strength assessed by hand grip and leg/back dynamometers in the week before academy. The body drag required the recruit to lift the dummy to standing and drag it 9.75 m as quickly as possible. Independent samples t-tests calculated between-sex differences in the drag and strength measures. Recruits were ranked according to drag time to describe the strength of recruits that could not perform the task. Pearson's correlations and a stepwise linear regression calculated relationships between the body drag and isometric strength. Male recruits completed the drag faster and were stronger than females (p < 0.001). Only two females could not complete the drag, and they had leg/back strength below 100 kg. Greater absolute (r = -0.599 and -0.677) and relative (r = -0.261 and -0.322) grip (combined score) and leg/back strength, respectively, related to a faster drag. Absolute leg/back strength predicted the body drag (r2 = 0.444). Improving absolute isometric grip and leg/back strength could enhance dragging ability. A minimum isometric leg/back strength score of 100 kg may be needed to perform a 74.84-kg body drag.

Analyzing the Training Load Demands, and Influence of Sex and Body Mass, on the Tactical Task of a Casualty Drag via Surface Electromyography Wearable Technology

This study measured the training load (TL) demands associated with a military-specific casualty drag measured via surface electromyography (sEMG) wearable technology, and the influence of sex and body mass on these measures. Thirty-six college-aged participants (males = 25; females = 11) performed two trials of a 123-kg (91-kg dummy with 32-kg load) backwards casualty drag over 15 m. Time was recorded to calculate drag velocity, with the fastest trial analyzed. Prior to testing, participants were fitted with compression garments embedded with sensors to measure the vastus lateralis and medialis (quadriceps; QUAD), biceps femoris (BF), and gluteus maximus (GM) of both legs. The sEMG signal for each muscle was measured as a percentage of maximal voluntary contraction to calculate TL. The variables included TL (total, QUAD, BF, GM), and between-muscle ratios. The sample was also ranked and median split via body mass into heavier and lighter groups. Independent samples t-tests calculated differences between drag velocity and TL for the sex and body mass groups. Pearson's correlations calculated relationships between body mass and velocity with the TL variables (combined, males, females). Females and lighter participants experienced greater TL compared to males and heavier participants, respectively (p < 0.01). A slower drag velocity correlated with a greater total and QUAD TL for all participants, males, and females (p ≤ 0.03, r = -0.65-0.80). Performing a slower casualty drag will increase TL demands, predominantly via QUAD stress. Training staff should develop the muscles important for the drag, especially for females and lighter males.

The Acute Effects of External Compression With Blood Flow Restriction on Maximal Strength and Strength-Endurance Performance of the Upper Limbs

The main goal of the present study was to evaluate the acute effects external compression with blood flow restriction (BFR) at 100 and 150% of full arterial occlusion pressure (AOP) on maximal strength and strength-endurance performance during the bench press (BP) exercise. The study included 12 strength-trained male subjects (age = 23.2 ± 2.66 years; body mass = 75.3 ± 6.33 kg; height = 179.1 ± 3.82 cm), experienced in resistance training (5.7 ± 2.93 years). During the experimental sessions in a randomized crossover design, the subjects performed a 1 repetition maximum (1RM) test and three sets of the BP using 60% 1RM to failure with three different conditions: without BFR (NO-BFR); BFR with a pressure of 100% AOP (BFR₁₀₀); and BFR with a pressure of 150% AOP (BFR₁₅₀). The differences between the NO-BFR, BFR₁₀₀, and BFR₁₅₀ conditions were examined using repeated measures ANOVA. The ANOVA indicated significant main effect for condition in 1RM, number of performed repetitions (REP), and time under tension (TUT) (p < 0.01). Post hoc analyses for the main effect indicated significant increases in 1RM (p < 0.01; 95.00 ± 15.37 vs 91.87 ± 15.99), REP (p < 0.01; 17.56 ± 3.36 vs 15.67 ± 5.24), and TUT (p < 0.01; 32.89 ± 6.40 vs 28.72 ± 6.18) for the BFR₁₅₀ condition compared to NO-BFR. Furthermore, significant increases in REP (p = 0.03; 17.56 ± 3.36 vs 16.47 ± 4.01) and TUT (p = 0.03; 32.89 ± 6.40 vs 30.00 ± 6.45) were observed for the BFR₁₅₀ condition compared to the BFR₁₀₀. The results of the present study indicate that high external compression increases maximal strength evaluated by the 1RM test, as well as endurance performance during three sets of the BP exercise.

Does Post-Activation Performance Enhancement Occur During the Bench Press Exercise under Blood Flow Restriction?

Background: The aim of the present study was to evaluate the effects of post-activation performance enhancement (PAPE) during successive sets of the bench press (BP) exercise under blood flow restriction (BFR). Methods: The study included 10 strength-trained males (age = 29.8 ± 4.6 years; body mass = 94.3 ± 3.6 kg; BP 1-repetition maximum (1RM) = 168.5 ± 26.4 kg). The experiment was performed following a randomized crossover design, where each participant performed two different exercise protocols: under blood flow restriction (BFR) and control test protocol (CONT) without blood flow restriction. During the experimental sessions, the study participants performed 3 sets of 3 repetitions of the BP exercise at 70%1RM with a 5 min rest interval between sets. The differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) between the CONT and BFR conditions were examined using 2-way (condition × set) repeated measures ANOVA. Furthermore, t-test comparisons between conditions were made for the set 2-set 1, set 3-set 1, and set 3-set 2 delta values for all variables. Results: The post hoc results for condition × set interaction in PP showed a significant increase in set 2 compared to set 1 for BFR (p < 0.01) and CONT (p = 0.01) conditions, a significant increase in set 3 compared to set 1 for the CONT (p = 0.01) condition, as well as a significant decrease in set 3 compared to set 1 for BFR condition occurred (p < 0.01). The post hoc results for condition × set interaction in PV showed a significant increase in set 2 compared to set 1 for BFR (p < 0.01) and CONT (p = 0.01) conditions, a significant increase in set 3 compared to set 1 for CONT (p = 0.03) condition, as well as a significant decrease in set 3 compared to set 1 for BFR condition (p < 0.01). The t-test comparisons showed significant differences in PP (p < 0.01) and PV (p = 0.01) for set 3-set 2 delta values between BFR and CONT conditions. Conclusion: The PAPE effect was analyzed through changes in power output and bar velocity that occurred under both the CONT and BFR conditions. However, the effects of PAPE have different kinetics in successive sets for BFR and for CONT conditions.

Stress in Academic and Athletic Performance in Collegiate Athletes: A Narrative Review of Sources and Monitoring Strategies

College students are required to manage a variety of stressors related to academic, social, and financial commitments. In addition to the burdens facing most college students, collegiate athletes must devote a substantial amount of time to improving their sporting abilities. The strength and conditioning professional sees the athlete on nearly a daily basis and is able to recognize the changes in performance and behavior an athlete may exhibit as a result of these stressors. As such, the strength and conditioning professional may serve an integral role in the monitoring of these stressors and may be able to alter training programs to improve both performance and wellness. The purpose of this paper is to discuss stressors experienced by collegiate athletes, developing an early detection system through monitoring techniques that identify the detrimental effects of stress, and discuss appropriate stress management strategies for this population.

Short-Term Blood Flow Restriction Increases Power Output and Bar Velocity During the Bench Press

Wilk, M, Krzysztofik, M, Filip, A, Zajac, A, Bogdanis, GC, and Lockie, RG. Short-term blood flow restriction increases power output and bar velocity during the bench press. J Strength Cond Res XX(X): 000-000, 2020-This study examined the effect of blood flow restriction (BFR) with 2 different types of cuffs on peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) in the bench press exercise (BP). Fourteen healthy strength-trained male athletes (age = 27.6 ± 3.5 years; body mass = 84.1 ± 8.0 kg; height = 175.8 ± 6.7 cm; BP 1 repetition maximum [RM] = 138.6 ± 17.8 kg) performed 3 different testing protocols as follows: without BFR (NO-BFR), BFR with a narrow cuff (BFRNARROW), and BFR with a wide cuff (BFRWIDE) in a randomized crossover design. During all sessions, subjects performed one set of 3 repetitions of the BP exercise using 70% 1RM. Cuff pressure was set to approximately 90% full arterial occlusion pressure of the upper limb at rest. Analyses of variance showed an increase in PP (by 21%, p < 0.01; effect size [ES] = 1.67), MP (by 16%, p < 0.01; ES = 0.93), PV (by 22%, p < 0.01; ES = 1.79), and MV (by 21%, p < 0.01; ES = 1.36) during BFRWIDE compared with NO-BFR and a significant increase in PP (by 15%, p < 0.01; ES = 1.07), MP (by 17%, p < 0.01; ES = 0.78), PV (by 18%, p < 0.01; ES = 1.65), and MV (by 13% p < 0.01; ES = 1.00) during BFRWIDE compared with BFRNARROW. There were no significant differences in any of the variable between NO-BFR and BFRNARROW. The results of the study indicate that short-term BFR training increases power output and bar velocity during the BP exercise. However, only BFRWIDE significantly influenced bar velocity and power output, which indicates that the width of the cuff is a critical factor determining acute exercise adaptation during BFR resistance training.

Relationships between Playing Time and Selected NBA Combine Test Performance in Division I Mid-Major Basketball Players

There has been limited analyses of DI mid-major male basketball players, and no analyses of relationships between athletic abilities and playing time in this population. The purpose of this study was to (1) describe and compare backcourt and frontcourt players from one mid-major team and (2) determine if there were relationships between playing time (total minutes, total games played, minutes per game) and select tests from the NBA Combine (height, body mass, standing reach, and wingspan; countermovement [VJ] and approach [AppVJ vertical jump], lane agility drill, ¾ court sprint, and 83.91-kg bench press). A retrospective analysis of data from the 2018 season for a men's DI team (n = 10) was conducted. Performance testing was completed in the pre-season, and playing time metrics were collated by the team's staff over the season. Players were split into backcourt (n = 6) and frontcourt (n = 4) groups and compared via independent samples t-tests (p < 0.05) and effect sizes (d). Pearson's correlations calculated relationships between playing time metrics and the NBA combine test data (p < 0.05). When compared to the backcourt group, the frontcourt group were significantly taller, heavier, had a greater standing reach and wingspan, and performed poorer in the VJ, AppVJ, and ¾ court sprint (d = 1.49-3.45). There were no significant relationships between playing time and any NBA Combine test (r = -0.363-0.511). Basketball-specific skill may have a larger impact on playing time in this mid-major team. However, the mid-major players in this study may have had above-average athletic abilities as measured by NBA combine testing, limiting correlations with playing time.

Heart Rate Responses during Simulated Fire Ground Scenarios among Full-Time Firefighters

Simulated fire ground scenarios (SFGS) provide firefighters with an opportunity to maintain skills, receive feedback, and optimize performance. Although there is extensive research on heart rate (HR) changes in the firefighter population, few examine the differences between positions. Firefighters are primarily responsible for fire suppression and control (23), officers for emergency operations and organizational management, paramedics for providing on-scene emergency medical care, and drivers are responsible for driving the fire apparatus. Utilizing HR analysis to quantify the physical demands of SFGS among firefighting crews by position. Sixty-seven male (age: 38.97 ± 9.17; ht: 177.99 ± 6.45 cm. wt: 88.83 ± 13.55 kg) firefighters (FF) participated in this investigation. FF crews performed two SFGS involving the suppression and control of a structural fire. Participants were outfitted with heart rate (HR) monitors and average heart rate (HRavg) and maximum heart rate (HRmax) data were collected for each of the two SFGS. Significant differences were observed for Age (P = 0.01), APMHR (P = 0.01), HRmax1 (P = 0.04), and HRmax2 (P = 0.04) in which firefighters had higher values for Age-predicted maximal heart rate (APMHR), HRmax1, HRmax2 compared to the officers. SFGS can be very physically demanding events that may elicit maximal or near maximal HR responses regardless of position. Based on the metabolic demands of these events and the individual firefighter's capabilities, this information can be used to develop resistance training and conditioning programs that optimize performance at maximal or near maximal heart rates.

In-Season Hip Thrust vs. Back Squat Training in Female High School Soccer Players

The barbell back squat provides a highly effective training stimulus to improve lower body strength, speed, and power, which are considered key components of athletic performance in many sports. The barbell hip thrust exercise utilizes similar musculature, and is popular among practitioners, but has received far less scientific examination. The purpose of this study was to evaluate the effects of an in-season resistance training program with hip thrusts or back squats on physical performance in adolescent female soccer players. Fourteen players completed identical whole-body resistance training twice per week for 6 weeks, except one group used the barbell hip thrust (HT) (n = 6) and the other the back squat (SQ) (n = 8). Improvements were observed for both groups in hip thrust 3RM (HT = 34.0%, SQ = 23.8%), back squat 3RM (HT = 34.6%, SQ = 31.0%), vertical jump (HT = 5.4%, SQ = 4.9%), broad jump (HT = 10.5%, SQ = 8.1%), ball kicking distance (HT = 13.2%, SQ = 8.1%), and pro-agility (HT = -1.5%, SQ = -1.5%; faster), but not 36.6-m dash (HT = 2.9%, SQ = 1.9%; slower) with no significant between-group differences. These data indicate that both the hip thrust and the squat provide an effective stimulus to improve these sport-specific performance measures. Practitioners should consider these findings in combination with other factors (equipment availability, ability to coach the movement, training goals, injuries, etc.) when selecting exercises.

The Effects of an Eight over Cricket Bowling Spell upon Pace Bowling Biomechanics and Performance within Different Delivery Lengths

Pace bowlers must often perform extended bowling spells with maximal ball release speed (BRS) while targeting different delivery lengths when playing a multi-day match. This study investigated the effect of an eight over spell upon pace bowling biomechanics and performance at different delivery lengths. Nine male bowlers (age = 18.8 ± 1.7 years) completed an eight over spell, while targeting different lengths (short: 7-10 m, good: 4-7 m, full: 0-4 m from the batter's stumps, respectively) in a randomized order. Trunk, knee and shoulder kinematics and ground reaction forces at front foot contact (FFC), as well as run-up velocity and BRS were measured. Paired sample t-tests (p ≤ 0.01), Hedges' g effect sizes, and statistical parametrical mapping were used to assess differences between mean variables from the first and last three overs. No significant differences (p = 0.05-0.98) were found in any discrete or continuous variables, with the magnitude of difference being trivial-to-medium (g = 0.00-0.73) across all variables. Results suggest pace bowlers sustain BRS through a single eight over spell while tolerating the repeatedly high whole-body biomechanical loads as suggested by maintaining the kinematics or technique at the assessed joints during FFC. Practically, the findings are advantageous for bowling performance and support current bowling load monitoring practices.

Cross-Sectional and Retrospective Cohort Analysis of the Effects of Age on Flexibility, Strength Endurance, Lower-Body Power, and Aerobic Fitness in Law Enforcement Officers

Lockie, RG, Dawes, JJ, Kornhauser, CL, and Holmes, RJ. Cross-sectional and retrospective cohort analysis of the effects of age on flexibility, strength endurance, lower-body power, and aerobic fitness in law enforcement officers. J Strength Cond Res 33(2): 451-458, 2019-There can be a great age range in cohorts of law enforcement officers. As the tasks required of officers generally do not change with advancing age, it is important to understand how physical performance in tests that assess job-specific characteristics may be altered. Retrospective analysis of performance test data of 383 officers (362 men and 21 women) was conducted. The tests included the following: sit-and-reach to determine hamstring and lower back flexibility; maximal push-up and sit-up repetitions in 60 seconds to measure muscle endurance; vertical jump (VJ) to assess lower-body power; and 2.4-km run to ascertain aerobic capacity. Data were stratified by age into 20-29, 30-39, 40-49, and 50-59 year groups, and analyzed by sex. A 1-way analysis of variance with the Bonferroni post hoc test was used to calculate the differences between the groups. Considering the male subjects, the 40-49 and 50-59 year groups performed poorer in the VJ, sit-up test, and 2.4-km run compared with the 20-29 year group (p ≤ 0.001-0.045). For the female subjects, the 20-29 year group was superior to the 30-39 (p = 0.013) and 40-49 (p = 0.025) year groups in the push-up test. To ensure that an older officer can successfully complete occupation-specific tasks, lower-body power, abdominal strength, and aerobic training should be completed. Female officers should also attempt to maintain relative upper-body strength. Practitioners must attempt to design training programs that fit within the context of the occupational demands, and potentially using a nontraditional training design as law enforcement officers may not have the time to follow a traditional periodization model.