Association of Dynamic Knee Valgus and Bone Stress Injury in US Military Academy Cadets.

CONTEXT: Early identification of incoming military personnel at elevated odds for bone stress injury (BSI) is important for the health and readiness of the US military. DESIGN: Prospective cohort study. METHODS: Knee kinematic data of the incoming US Military Academy cadets were collected while performing a jump-landing task (The Landing Error Scoring System) using a markerless motion capture system and depth camera. Data on incidence of lower-extremity injury, including BSI, were collected throughout the study period. RESULTS: A total of 1905 participants (452 females, 23.7%) were examined for knee valgus and BSI status. A total of 50 BSI occurred during the study period (incidence proportion = 2.6%). The unadjusted odds ratio for BSI at initial contact was 1.03 (95% confidence interval [CI], 0.94-1.14; P = .49). Adjusted for sex, the odds ratio for BSI at initial contact was 0.97 (95% CI, 0.87-1.06; P = .47). At the instant of maximum knee-flexion angle, the unadjusted odds ratio was 1.06 (95% CI, 1.02-1.10; P = .01), and the odds ratio was 1.02 (95% CI, 0.98-1.07; P = .29) after adjusting for sex. This suggests that there was not a significant enough association for an increase in the odds of BSI based on either degree of knee valgus. CONCLUSIONS: Our results did not demonstrate an association between knee valgus angle data during a jump-landing task and future increased odds of BSI in a military training population. Further analysis is warranted, but the results suggests the association between kinematics and BSI cannot be effectively screened by knee valgus angle data in isolation.

Youth Perceptions of Sport-Confidence.

ABSTRACT: Zuk, EF, Maksymiw, K, Evanovich, J, McGarry, JE, Root, HJ, and Distefano, LJ. Youth perceptions in sport-confidence. J Strength Cond Res 35(11): 3232-3235, 2021-Sport-confidence is an important construct that is often missed during physical activity interventions in youth. Male and female children might display differences in sport-confidence that influences their activity levels. The purpose of this study is to assess any association between sport-confidence and gender in elementary school and middle-school children. All 286 children {(boys [ES: n = 71, age = 8±1 years; MS: n = 63, 11±1 years]; girls [ES: n = 67, 7±1 years; MS: n = 85, 11±1 years])} completed the Physical Literacy Assessment for Youth-Self Questionnaire. Separate chi-square tests of the association were used to evaluate the association between gender and sport-confidence among elementary (grades K-4) and middle-school (grades 5-8) children because of varying injury and participation rates for these groups, for each relevant question with a significance set at p ≤ 0.05. For elementary school children, there were no significant associations between genders and sport-confidence (p > 0.05). In middle-school children, there were significant associations detected for learning new skills (ϕ = 0.12; p = 0.031), perception of skill (ϕ = 0.12; p = 0.054), confidence in activity (ϕ = 0.17; p = 0.035), and being the best in the class (ϕ = 0.15; p = 0.048) between genders and sport-confidence. For all results, boys displayed more sport-confidence than girls. Education for key stakeholders about the importance of including sport-confidence in physical activity interventions is integral in promoting life-long activity, specifically in middle-school girls.

The Utilization of Core Exercises in Patients With Patellofemoral Pain: A Critically Appraised Topic.

Clinical Scenario: Patellofemoral pain (PFP) is characterized by general anterior knee pain around the patella and is one of the most prevalent knee conditions. PFP is challenging to treat due to a wide range of contributing factors and often has chronic, reoccurring symptoms. Traditional treatment focuses on quadriceps and gluteal strengthening with minimal emphasis on deep trunk musculature. Recently, there has been a growing body of literature supporting the beneficial effects of core stability exercises as a treatment option for PFP. Clinical Question: Are core stability exercises coupled with traditional rehabilitation more effective than only traditional rehabilitation techniques for decreasing pain in patients with PFP? Summary of Key Findings: Three articles met the inclusion criteria and investigated core strengthening exercises as a treatment for PFP. Two studies investigated a 4-week exercise protocol and demonstrated a greater decrease in pain when compared to the control group. The third study examined the effects of a 6-week program where both the intervention and control groups resulted in similar reduction of pain. All articles included received a minimum of 6 on the PEDro scale. Clinical Bottom Line: There is evidence that supports core stability exercise protocols coupled with traditional rehabilitation as being more effective in reducing pain in patients with PFP when compared to traditional rehabilitation alone. Strength of Recommendation: The grade of A is recommended based on the Strength of Recommendation Taxonomy.

Demographic Characteristics Among Patients With Chronic Exertional Compartment Syndrome of the Lower Leg.

Clinical Scenario: Chronic exertional compartment syndrome (CECS) is a condition related with ischemia of the body's tissue due to increases in intracompartmental pressures, which involves, among other symptoms, pain with exertion. CECS is often overlooked or misdiagnosed due to an ambiguous presentation. Diagnostic accuracy of CECS and subsequent management can be improved when contributing factors are known. Research is lacking on the type of patient most likely to experience CECS, highlighting the need for identification of common demographic characteristics among affected individuals. Clinical Question: What are the common demographic characteristics among patients exhibiting CECS of the lower leg? Summary of Key Findings: Four studies were identified (1 prospective consecutive study, 2 retrospective reviews, and 1 retrospective cohort study) that examined common characteristics among patients with CECS. Conflicting evidence exists on whether CECS is more commonly seen in men or in women. CECS has often been reported in young, active individuals but may present in older populations as well. Soccer, field hockey, lacrosse, competitive running, and speed skating have been associated with an increased likelihood of CECS development. Clinical Bottom Line: Current evidence has identified commonalities in sex, age, and sport participation as characteristics often present among individuals experiencing lower leg CECS. Other factors, such as overuse, trauma, diabetes, and gait mechanics, have also been identified in association with CECS. Further data through future prospective studies will help confirm the type of patient mostly likely to experience CECS. Strength of Recommendation: Grade B evidence exists that certain sex, age, and sport participation demographic characteristics are common among patients with CECS of the lower leg.

Protracted Cardiovascular Impairments After Anterior Cruciate Ligament Injury: A Critically Appraised Topic.

Clinical Scenario: Anterior cruciate ligament (ACL) tear is a devastating knee injury with negative long-term consequences, such as early-onset knee osteoarthritis, biomechanical compensations, and reduced physical activity. Significant reduction in physical activity is a powerful indicator of cardiovascular (CV) disease; therefore, those with a history of ACL injury may be at increased risk for CV disease compared with noninjured individuals. Focused Clinical Question: Do individuals with a history of ACL injury demonstrate negative CV changes compared with those without a history of ACL injury? Summary of Key Findings: Three articles met the inclusion criteria and investigated CV changes after ACL injury. Both cross-sectional studies compared participants with ACL injury with matched controls. Bell et al compared time spent in moderate to vigorous physical activity and step count, whereas Almeida et al compared maximum rate of oxygen consumption, ventilatory thresholds, isokinetic quadriceps strength, and body composition. Collectively, both quantitative studies found that individuals with a history of ACL injury had less efficient CV systems compared with matched controls and/or preoperative data. Finally, a qualitative study of 3506 retired National Football League athletes showed an increased rate of arthritis and knee replacement surgery after an ACL injury when compared with other retired National Football League members, in addition to a >50% increased rate of myocardial infarction. Clinical Bottom Line: A history of ACL injury is a source of impaired physical activity. Preliminary data indicate that these physical activity limitations negatively impair the CV system, and individuals with a history of ACL injury demonstrate lower maximum oxygen consumption, self-reported disability, and daily step count compared with noninjured peers. These complications support the need for greater emphasis on CV wellness. Strength of Recommendation: Consistent findings from 2 cross-sectional studies and 1 survey study suggest level IIB evidence to support that ACL injury is associated with negative CV health.

Does Dehydration Affect the Adaptations of Plasma Volume, Heart Rate, Internal Body Temperature, and Sweat Rate During the Induction Phase of Heat Acclimation?

Clinical Scenario: Exercise in the heat can lead to performance decrements and increase the risk of heat illness. Heat acclimation refers to the systematic and gradual increase in exercise in a controlled, laboratory environment. Increased duration and intensity of exercise in the heat positively affects physiological responses, such as higher sweat rate, plasma volume expansion, decreased heart rate, and lower internal body temperature. Many heat acclimation studies have examined the hydration status of the subjects exercising in the heat. Some of the physiological responses that are desired to elicit heat acclimation (ie, higher heart rate and internal body temperature) are exacerbated in a dehydrated state. Thus, euhydration (optimal hydration) and dehydration trials during heat acclimation induction have been conducted to determine if there are additional benefits to dehydrated exercise trials on physiological adaptations. However, there is still much debate over hydration status and its effect on heat acclimation. Clinical Question: Does dehydration affect the adaptations of plasma volume, heart rate, internal body temperature, skin temperature, and sweat rate during the induction phase of heat acclimation? Summary of Findings: There were no observed differences in plasma volume, internal body temperature, and skin temperature following heat acclimation in this critically appraised topic. One study found an increase in sweat rate and another study indicated greater changes in heart rate following heat acclimation with dehydration. Aside from these findings, all 4 trials did not observe statistically significant differences in euhydrated and dehydrated heat acclimation trials. Clinical Bottom Line: There is minimal evidence to suggest that hydration status affects heat acclimation induction. In the studies that met the inclusion criteria, there were no differences in plasma volume concentrations, internal body temperature, and skin temperature. Strength of Recommendation: Based on the Oxford Centre for Evidence-Based Medicine Scale, Level 2 evidence exists.

Examining the Relationship Between Neuroplasticity and Learned Helplessness After ACLR: Early Versus Late Recovery.

CONTEXT: Altered neural signaling is known to have a direct impact on psychological wellness. Therefore, disruptions in neural signaling after anterior cruciate ligament reconstruction may influence psychological dysfunction, in some cases manifesting as learned helplessness. Helplessness is a psychological paradigm that presents as altered neuromuscular control, reduced motivation, and psychological deficits. OBJECTIVES: The authors sought to evaluate the relationship between helplessness, neural activity, and quadriceps function at different time points after anterior cruciate ligament reconstruction. EVIDENCE ACQUISITION: Twenty-nine individuals with unilateral anterior cruciate ligament reconstruction were categorized into early group (<2 y, age: 19.13 [2.18] y; height: 1.77 [0.11] m; mass: 76.903 [11.87] kg) or late group (>2 y, age: 22 [23] y; height: 1.67 [0.07] m; mass: 65.66 [11.33] kg). Quadriceps function (activation and strength), spinal-reflexive and corticospinal excitability (active motor thresholds and motor evoked potentials), and helplessness were obtained. A principal component analysis was performed by group (early and late) to identify which factors of helplessness were most associated with neural activity and quadriceps function. Pearson product moment correlation analyses were performed by group to determine associations between individual components and main outcomes. EVIDENCE SYNTHESIS: In the early group, cognitive readiness was associated with quadriceps strength of the injured limb (r2 = .513, P = .004), and self-awareness/management was associated with motor threshold of the injured limb (r2 = .238, P = .05). In the late group, intrinsic helplessness was associated with motor output of injured limb (r2 = .653, P = .01). CONCLUSION: Helplessness is made up of several attributional constructs, which are altered at different phases of recovery. Helplessness constructs interact differently with neural activity and quadriceps function across time. These findings are preliminary and do not establish a causal link between neural alterations and learned helplessness. Future studies should serially evaluate both changes in neural activity and learned helplessness attributes throughout recovery.

Heat Exposure and Hypohydration Exacerbate Physiological Strain During Load Carrying.

Adams, EL, Casa, DJ, Huggins, RA, DeMartini-Nolan, JK, Stearns, RL, Kennedy, RM, Bosworth, MM, DiStefano, LJ, Armstrong, LE, and Maresh, CM. Heat exposure and hypohydration exacerbate physiological strain during load carrying. J Strength Cond Res 33(3): 727-735, 2019-Heat exposure and hypohydration induce physiological and psychological strain during exercise; however, it is unknown if the separate effects of heat exposure and hypohydration are synergistic when co-occurring during loaded exercise. This study compared separate and combined effects of heat exposure and hypohydration on physiological strain, mood state, and visual vigilance during loaded exercise. Twelve men (mean ± SD; age, 20 ± 2 years; body mass, 74.0 ± 8.2 kg; maximal oxygen uptake, 57.0 ± 6.0 ml·kg·min) completed 4 trials under the following conditions: euhydrated temperate (EUT), hypohydrated temperate (HYT), euhydrated hot (EUH), and hypohydrated hot (HYH). Exercise was 90 minutes of treadmill walking (∼50% V[Combining Dot Above]O2max, 5% grade) while carrying a 45-lb rucksack. Profile of Mood States and the Scanning Visual Vigilance Test were completed before and after exercise. The separate effects of heat exposure (EUH) and hypohydration (HYT) on post-exercise rectal temperature (Tre) were similar (38.25 ± 0.63°C vs. 38.22 ± 0.29°C, respectively, p > 0.05), whereas in combination (HYH), post-exercise Tre was far greater (39.32 ± 0.43°C). Increase in Tre per 1% body mass loss (BML) for HYH (vs. EUH) was greater than HYT (vs. EUT) (0.32 vs. 0.04°C, respectively, p = 0.02); heart rate increase per 1% BML for HYH (vs. EUH) was 7 b·min compared with HYT (vs. EUT) at 3 b·min (p = 0.30). Hypohydrated hot induced greater mood disturbance (post-exercise - pre-exercise) (35 ± 21 units) compared with other conditions (EUT = 3 ± 9 units; HYT = 3 ± 16 units; EUH = 16 ± 26 units; p < 0.001). No differences occurred in visual vigilance (p > 0.05). Independently, heat exposure and hypohydration induced similar physiological strain during loaded exercise; when combined, heat exposure with hypohydration, synergistically exacerbated physiological strain and mood disturbance.

Effect of a Lower Extremity Preventive Training Program on Physical Performance Scores in Military Recruits.

Peck, KY, DiStefano, LJ, Marshall, SW, Padua, DA, Beutler, AI, de la Motte, SJ, Frank, BS, Martinez, JC, and Cameron, KL. Effect of a lower extremity preventive training program on physical performance scores in military recruits. J Strength Cond Res 31(11): 3146-3157, 2017-Exercise-based preventive training programs are designed to improve movement patterns associated with lower extremity injury risk; however, the impact of these programs on general physical fitness has not been evaluated. The purpose of this study was to compare fitness scores between participants in a preventive training program and a control group. One thousand sixty-eight freshmen from a U.S. Service Academy were cluster-randomized into either the intervention or control group during 6 weeks of summer training. The intervention group performed a preventive training program, specifically the Dynamic Integrated Movement Enhancement (DIME), which is designed to improve lower extremity movement patterns. The control group performed the Army Preparation Drill (PD), a warm-up designed to prepare soldiers for training. Main outcome measures were the Army Physical Fitness Test (APFT) raw and scaled (for age and sex) scores. Independent t tests were used to assess between-group differences. Multivariable logistic regression models were used to control for the influence of confounding variables. Dynamic Integrated Movement Enhancement group participants completed the APFT 2-mile run 20 seconds faster compared with the PD group (p < 0.001), which corresponded with significantly higher scaled scores (p < 0.001). Army Physical Fitness Test push-up scores were significantly higher in the DIME group (p = 0.041), but there were no significant differences in APFT sit-up scores. The DIME group had significantly higher total APFT scores compared with the PD group (p < 0.001). Similar results were observed in multivariable models after controlling for sex and body mass index (BMI). Committing time to the implementation of a preventive training program does not appear to negatively affect fitness test scores.

Longitudinal Changes in Hip Strength and Range of Motion in Female Youth Soccer Players: Implications for ACL Injury, A Pilot Study.

CONTEXT: Risk of anterior cruciate ligament (ACL) injuries in young female athletes increases with age, appearing to peak during maturation. Changes in hip muscle strength and range of motion (ROM) during this time may contribute to altered dynamic movement patterns that are known to increase risk of ACL injuries. Understanding the longitudinal changes in hip strength and ROM is needed to develop appropriate interventions to reduce the risk of ACL injuries. OBJECTIVE: To examine the longitudinal changes in hip strength and ROM in female youth soccer players. DESIGN: Longitudinal descriptive study. SETTING: Field setting. PARTICIPANTS: 14 female youth soccer athletes (14.1 ± 1.1 y, 165.8 ± 5.3 cm, 57.5 ± 9.9 kg) volunteered as part of a multiyear risk factor screening project. MAIN OUTCOME MEASURES: Clinical measures of hip strength and ROM were collected annually over 3 consecutive years. Passive hip internal rotation (IR), external rotation (ER), abduction (ABD), and adduction (ADD) ROM were measured with a digital inclinometer. Isometric hip ABD and extension (EXT) strength were evaluated using a hand-held dynamometer. Separate repeated-measures ANOVAs compared hip strength and ROM values across 3 consecutive years (P < .05). RESULTS: As youth female soccer players increased in age, there were no changes in normalized hip ABD (P = .830) or EXT strength (P = .062) across 3 consecutive years. Longitudinal changes in hip ROM were observed with increases in hip IR (P = .001) and ABD (P < .001), while hip ADD (P = .009) and ER (P < .001) decreased. CONCLUSIONS: Anatomical changes at the hip occur as youth female soccer players increase in age. While there are no changes in hip strength, there is an increase in hip IR and ABD ROM with a concomitant decrease in hip ER and ADD ROM. The resulting asymmetries in hip ROM may decrease the activation and force producing capabilities of the hip muscles during dynamic activities, contributing to altered lower extremity mechanics known to increase the risk of ACL injuries.

Landing Technique Improvements After an Aquatic-Based Neuromuscular Training Program in Physically Active Women.

CONTEXT: Neuromuscular training programs (NTPs) improve landing technique and decrease vertical ground-reaction forces (VGRFs), resulting in injury-risk reduction. NTPs in an aquatic environment may elicit the same improvements as land-based programs with reduced joint stress. OBJECTIVE: To examine the effects of an aquatic NTP on landing technique as measured by the Landing Error Scoring System (LESS) and VGRFs, immediately and 4 mo after the intervention. DESIGN AND SETTING: Repeated measures, pool and laboratory. PARTICIPANTS: Fifteen healthy, recreationally active women (age 21 ± 2 y, mass 62.02 ± 8.18 kg, height 164.74 ± 5.97 cm) who demonstrated poor landing technique (LESS-Real Time > 4). INTERVENTIONS: All participants completed an aquatic NTP 3 times/wk for 6 wk. MAIN OUTCOME MEASURES: Participants' landing technique was evaluated using a jump-landing task immediately before (PRE), immediately after (POST), and 4 mo after (RET) the intervention period. A single rater, blinded to time point, graded all videos using the LESS, which is a valid and reliable movement-screening tool. Peak VGRFs were measured during the stance phase of the jump-landing test. Repeated-measure analyses of variance with planned comparisons were performed to explore differences between time points. RESULTS: LESS scores were lower at POST (4.46 ± 1.69 errors) and at RET (4.2 ± 1.72 errors) than at PRE (6.30 ± 1.78 errors) (P < .01). No significant differences were observed between POST and RET (P > .05). Participants also landed with significantly lower peak VGRFs (P < .01) from PRE (2.69 ± .72 N) to POST (2.23 ± .66 N). CONCLUSIONS: The findings introduce evidence that an aquatic NTP improves landing technique and suggest that improvements are retained over time. These results show promise of using an aquatic NTP when there is a desire to reduce joint loading, such as early stages of rehabilitation, to improve biomechanics and reduce injury risk.

Maturation and Sex Differences in Neuromuscular Characteristics of Youth Athletes.

Understanding how neuromuscular factors that are associated with lower extremity injury risk, such as landing kinematics, muscle strength, and flexibility, change as children mature may enhance age-specific recommendations for injury prevention programs. The purpose of this study was to compare these factors in prepubertal, pubertal, and postpubertal male and female athletes. Subjects were classified on maturation stage (prepubertal: 16 males, 15 females, age: 9 ± 1 years; pubertal: 13 males, 12 females, age: 12 ± 3 years; postpubertal: 30 males, 27 females, age: 16 ± 2 years). Researchers measured lower extremity isometric muscle strength and flexibility and evaluated kinematics and vertical ground reaction forces (VGRFs) during a jump-landing task. Three-dimensional kinematics at initial contact (IC), joint displacements, and peak VGRF were calculated. Separate multivariate analyses of variance were performed to evaluate sex and maturation differences (α ≤ 0.05). Postpubertal females landed with less knee flexion at IC (p = 0.006) and demonstrated lower knee extension strength (p = 0.01) than prepubertal and pubertal females. Postpubertal males landed with less hip adduction displacement (postpubertal males = 12.53 ± 6.15°, prepubertal males = 18.84 ± 7.47°; p = 0.04) and less peak VGRF (postpubertal males = 1.53 ± 0.27% body weight [BW], prepubertal males = 1.99 ± 0.32% BW; p = 0.03) compared with prepubertal males. These findings suggest encouraging sagittal plane absorption and decreasing frontal plane motion at the hip, whereas maintaining quadriceps strength may be important for reducing injury risk in postpubertal athletes.

Developmental differences between boys and girls result in sex-specific physical fitness changes from fourth to fifth grade.

To better understand how developmental differences impact performance on a broad selection of common physical fitness measures, we examined changes in boys and girls from fourth to fifth grade. Subjects included 273 boys (age, 9.5 ± 0.6 years; height, 139.86 ± 7.52 cm; mass, 38.00 ± 9.55 kg) and 295 girls (age, 9.6 ± 0.5 years; height, 139.30 ± 7.19 cm; weight, 37.44 ± 9.35 kg). We compared anthropometrics, cardiorespiratory and local muscular endurance, flexibility, power, and strength. A mixed-method analysis of variance was used to compare boys and girls at the 2 time points. Pearson correlation coefficients were used to examine relationships between anthropometric and fitness measurements. Significance was set at p ≤ 0.05. Weight increased significantly (>10%) in both sexes, and girls became significantly taller than boys after growing 4.9% by fifth grade (vs. 3.5%). Both groups improved cardiorespiratory endurance and power, although boys performed better than girls at both time points. Boys were stronger in fourth grade, but girls improved more, leading to similar fifth-grade values. Girls were more flexible in fourth grade, but their significant decreases (∼32.4%) coupled with large improvements in boys (∼105%) resulted in similar fifth-grade scores. Body mass index (BMI) was positively correlated with run time regardless of grade or sex. Power was negatively correlated with BMI and run time in fourth grade. In conclusion, sex-specific differences in physical fitness are apparent before pubescence. Furthermore, this selection of measures reveals sexually dimorphic changes, which likely reflect the onset of puberty in girls. Coaches and teachers should account these developmental differences and their effects on anthropometrics and fitness in boys and girls.

Jump-landing differences between varsity, club, and intramural athletes: the Jump-ACL Study.

Abnormal movement patterns have been identified as important prospective risk factors for lower extremity injury, including anterior cruciate ligament injury. Specifically, poor neuromuscular control during the early landing phase has been associated with increased injury risk. Although it is commonly assumed that higher division collegiate athletes generally exhibit better movement patterns than lower division athletes, few studies compare the biomechanical differences on basic tasks such as jump landing between various levels of athletic groups. The objective of this study was to evaluate jump-landing and fitness differences among college-aged Intramural, Competitive Club, and National Collegiate Athletic Association (NCAA) Division I level athletes. Two hundred seventy-seven student-athletes (222 men, 55 women; age 19.3 ± 0.8 years) categorized as NCAA Division I, Competitive Club, or Intramural level athletes were evaluated during a jump-landing task using the Landing Error Scoring System (LESS), a validated qualitative movement assessment. Fitness was measured using the Army Physical Fitness Test (APFT). Results showed no significant differences in landing errors between the levels of athletic group (F(2,267) = 0.36, p = 0.70). There was a significant difference in landing errors between genders (F(1,268) = 3.99, p = 0.05). Significant differences in APFT scores were observed between level of athletic group (F(2,267) = 11.14, p < 0.001) and gender (F(1,268) = 9.27, p = 0.003). There was no significant correlation between the APFT and LESS scores (p = 0.26). In conclusion, higher level athletes had better physical fitness as measured by the APFT but did not as a group exhibit better landing technique. The implications of this research suggest that "high-risk" movement patterns are prevalent in all levels of athletes.

Comparison of integrated and isolated training on performance measures and neuromuscular control.

Traditional weight training programs use an exercise prescription strategy that emphasizes improving muscle strength through resistance exercises. Other factors, such as stability, endurance, movement quality, power, flexibility, speed, and agility are also essential elements to improving overall functional performance. Therefore, exercises that incorporate these additional elements may be beneficial additions to traditional resistance training programs. The purpose of the study was to compare the effects of an isolated resistance training program (ISO) and an integrated training program (INT) on movement quality, vertical jump height, agility, muscle strength and endurance, and flexibility. The ISO program consisted of primarily upper and lower extremity progressive resistance exercises. The INT program involved progressive resistance exercises, and core stability, power, and agility exercises. Thirty subjects were cluster randomized to either the ISO (n = 15) or INT (n = 15) training program. Each training group performed their respective programs 2 times per week for 8 weeks. The subjects were assessed before (pretest) and after (posttest) the intervention period using the following assessments: a jump-landing task graded using the Landing Error Scoring System (LESS), vertical jump height, T-test time, push-up and sit-up performance, and the sit-and-reach test. The INT group performed better on the LESS test (pretest: 3.90 ± 1.02, posttest: 3.03 ± 1.02; p = 0.02), faster on the T-test (pretest: 10.35 ± 1.20 seconds, posttest: 9.58 ± 1.02 seconds; p = 0.01), and completed more sit-ups (pretest: 40.20 ± 15.01, posttest: 46.73 ± 14.03; p = 0.045) and push-ups (pretest: 40.67 ± 13.85, posttest: 48.93 ± 15.17; p = 0.05) at posttest compared with pretest, and compared with the ISO group at posttest. Both groups performed more push-ups (p = 0.002), jumped higher (p < 0.001), and reached further (p = 0.008) at posttest compared with that at pretest. Performance enhancement programs should use an integrated approach to exercise selection to optimize performance and movement technique benefits.

Effects of resistance training fatigue on joint biomechanics.

Resistance training has been found to have a multitude of benefits. However, when performed with short rest, resistance training can result in substantial fatigue, which may have a negative impact on exercise technique. The purpose of this study is to examine the effects of fatigue from resistance exercise on joint biomechanics to determine what residual movement effects may exist after the workout. Twelve men with at least 6 months of resistance training experience (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg) performed 5 body weight squats before (pretest) and after (posttest) a highly fatiguing resistance training workout. Lower extremity biomechanics were assessed using a 3-dimensional motion analysis system during these squats. Peak angle, total displacement, and rate were assessed for knee flexion, trunk flexion, hip flexion, hip rotation, and hip adduction. Results showed a significant decrease in peak angle for knee flexion (Pre: 120.28 ± 11.93°, Post: 104.46 ± 9.85°), hip flexion (Pre: -109.42 ± 12.49°, Post: -95.8 ± 12.30°), and hip adduction (Pre: -23.32 ± 7.04°, Post: -17.30 ± 8.79°). There was a significant reduction in angular displacement for knee flexion (Pre: 115.56 ± 10.55°, Post: 103.35 ± 10.49°), hip flexion (Pre: 97.94 ± 10.69°, Post: 90.51 ± 13.22°), hip adduction (Pre: 17.79 ± 7.36°, Post: 11.89 ± 4.34°), and hip rotation (Pre: 30.72 ± 12.28, Post: 20.48 ± 10.12). There was also a significant reduction in displacement rate for knee flexion (Pre: 2.20 ± 0.20, Post: 1.98 ± 0.20), hip flexion (Pre: 1.92 ± 0.20, Post: 1.76 ± 0.27), hip adduction (Pre: -0.44 ± 0.17, Post: -0.31 ± 0.17), and hip rotation (Pre: 0.59 ± 0.23, Post: 0.38 ± 0.21). This study demonstrated that there are lasting residual effects on movement capabilities after a high-intensity short rest protocol. Thus, strength and conditioning coaches must be careful to monitor movements and exercise techniques after such workouts to prevent injury and optimize subsequent exercise protocols that might be sequenced in order.

Strength Training Rehabilitation Incorporating Power Exercises (STRIPE) for individuals with patellofemoral pain: a randomised controlled trial protocol.

Patellofemoral pain (PFP) is a chronic condition that presents with patellar pain during various daily and recreational activities. Individuals with PFP have a wide range of impairments that result in long-term disability and reduced quality of life. Current interventions target hip muscle weakness with strength-based exercises, but recurrence rates are as high as 90%. A single feasibility study demonstrated success with power-based exercises; however, there is limited evidence evaluating pain or self-reported function in larger cohorts, and no study has assessed recurrence rates. This protocol details a study evaluating a strength-based rehabilitation programme compared with a strength-based programme incorporating power-based exercises in individuals with PFP. This single-blinded randomised controlled trial will evaluate 88 participants with PFP, aged 18-40 years old. Participants will be recruited from three universities, the surrounding community and sports medicine clinics. Participants will receive three telemedicine rehabilitation sessions a week for 6 weeks. The rehabilitation programme will consist of either strength-based exercises or a combination of power and strength-based exercises. Pain, subjective function and recurrence rates will be assessed at baseline, immediately after the intervention and at four follow-up time points: 6-month, 12-month, 18-month and 24-month postintervention. We will also assess neuromuscular function of the hips and global rating of change at each postintervention time point. Trial registration number NCT05403944.

Carbon Fiber Insoles Enhance Perception of Performance Despite Variable Objective Outcomes: Specific to the Moderately Active Individual.

Carbon fiber insoles (CFIs) may benefit performance in elite athletes, however, their use in moderately active individuals has been adopted without evidence supporting such enhancements in this population. Fifteen male subjects performed vertical jump (VJ) and repeat treadmill sprint tests before and after a VO2peak while wearing 1) CFIs and 2) control insoles (CON). Subjects completed a subjective survey regarding their perceived performance abilities for both conditions. There were no significant differences between CFIs and CON in VJ height, sprint distance, heart rate following sprints; and rate of oxygen consumption, perceived fatigue, and perceived exertion at 85% of maximal speed (p > 0.05) during the VO2peak. At maximal speed, although there was no difference between conditions in peak rate of oxygen consumption (95%CI [-4.85, 0.21]) and respiratory exchange ratio (95%CI [-0.01, 0.03]), CFIs resulted in a reduced level of perceived fatigue (95%CI [-1, 0]) and perceived exertion (95%CI [-2, 0]) compared to CON. Subjects subjectively reported increased feelings of "propulsion or explosiveness" (p = 0.026) and being able to "perform better while jumping" (p = 0.029) while wearing CFIs. Heightened perceptions of performance enhancements when wearing CFIs indicate, in the moderately active, perceptual benefits could be more influential for determining CFI use.

A dynamic warm-up model increases quadriceps strength and hamstring flexibility.

Research suggests that static stretching can negatively influence muscle strength and power and may result in decreased functional performance. The dynamic warm-up (DWU) is a common alternative to static stretching before physical activity, but there is limited research investigating the effects of a DWU. The purpose of this study was to compare the acute effects of a DWU and static stretching warm-up (SWU) on muscle flexibility, strength, and vertical jump using a randomized controlled trial design. Forty-five volunteers were randomly assigned into a control (CON), SWU, or DWU group. All participants rode a stationary bicycle for 5 minutes and completed a 10-minute warm-up protocol. During this protocol, the DWU group performed dynamic stretching and running, the SWU group performed static stretching, and the CON group rested. Dependent variables were measured immediately before and after the warm-up protocol. A digital inclinometer measured flexibility (degrees) for the hamstrings, quadriceps, and hip flexor muscles. An isokinetic dynamometer measured concentric and eccentric peak torque (N·m/kg) for the hamstrings and quadriceps. A force plate was used to measure vertical jump height (meters) and power (watts). In the DWU group, there was a significant increase in hamstring flexibility (pretest: 26.4 ± 13.5°, posttest: 16.9 ± 9.4°; p < .0001) and eccentric quadriceps peak torque (pretest: 2.49 ± 0.83 N·m/kg, posttest: 2.78 ± 0.69 N·m/kg; p = 0.04). The CON and SWU did not significantly affect any flexibility, strength, or vertical jump measures (p > 0.05). The DWU significantly improved eccentric quadriceps strength and hamstrings flexibility, whereas the SWU did not facilitate any positive or negative changes in muscle flexibility, strength, power, or vertical jump. Therefore, the DWU may be a better preactivity warm-up choice than an SWU.

Hybrid effectiveness-implementation study designs in sports injury prevention research.

Despite vast evidence supporting the effectiveness of lower extremity injury prevention programs in a variety of sport settings, age groups, and levels of competition, there is limited evidence on implementation strategies that positively impact the feasibility, scale-up and sustainability of such programs. Sport-related injury prevention is affected by the research-to-practice gap, a pervasive issue in healthcare, where high-quality experimental research is not used in routine clinical practice. An intervention shown to be efficacious in a controlled environment, such as a lab or in a field-study conducted by scientists, will demonstrate a decline in benefit when implemented in the intended clinical setting. Real-world considerations, such as foundational knowledge and training, time constraints, or end user motivation, influence the quality and consistency of implementation. Acknowledging and addressing implementation barriers in a systematic way is essential to promote effective program dissemination. Study design methods that measure both clinical effectiveness and implementation strategies need to be identified. Hybrid effectiveness-implementation designs simultaneously measure both an intervention's effect on clinical outcomes as well as critical information related to implementation strategy; however these study designs are not frequently utilized. The purpose of this mini-review is to describe: the basics of hybrid designs, rationale for using hybrid designs, and examples of how these designs could be used in athletic healthcare injury prevention research.