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Introduction Reserve Officers' Training Corps (ROTC) trainees are college students who complete military courses and participate in physical and tactical training under the direction of military Service Members assigned to ROTC programs to serve as faculty and staff at US colleges. ROTC trainees report musculoskeletal injuries (MSKIs) attributable to ROTC training in line with MSKI incidence in other training environments. However, concealment is prevalent, as 66% of MSKIs in ROTC go unreported. The current study investigated if a brief, online educational video could increase ROTC trainees' reporting intentions. In addition, we investigated if the message's source (i.e. peer or authority figure) affected reporting intentions. Materials and Methods A repeated measures design was used to evaluate the impact of 2 MSKI educational interventions, one delivered by a high-achieving Army ROTC trainee (peer-led) and the other delivered by an Army ROTC battalion commander (authority-led), on MSKI reporting intentions, as compared to each other and a control intervention. Other than their personal introductions, both individuals had the same script addressing 4 areas: (1) MSKI prevalence in ROTC, (2) evidence of improved outcomes with early treatment, (3) encouraging injury reporting, and (4) addressing specific barriers and stigma beliefs previously identified in ROTC. The control condition consisted of a video demonstrating exercise technique with voiceover. A survey was developed to measure stigma regarding MSKI reporting and intentions to seek help for MSKI. ROTC trainees at 23 universities were invited to participate via an anonymous survey link. Participants completed the following using an online survey platform: (1) pre-intervention MSKI intentions scale, (2) randomly assigned intervention video, and (3) repeat MSKI intentions scale post-intervention. A two-way mixed, ANOVA was performed to assess interaction effects and main effects pre- and post-intervention. Results One-hundred ROTC trainees (39% female; age = 21 ± 2 years, ROTC experience = 2 ± 1 years) completed the study. Participants were primarily from Army ROTC programs (72 Army, 14 Air Force, and 14 Naval). Pre-intervention survey scores (possible score range 8–56 with lower scores indicating greater intention to seek help): authority-led (n  = 31) 20.3 ± 9.4, peer-led (n  = 32) 21.8 ± 8.7, control (n  = 37) 19.1 ± 10.1, total 20.3 ± 9.4. Post-intervention scores: authority-led 20.9 ± 11.2, peer-led 20.2 ± 10.0, control 17.3 ± 7.7, total 19.7 ± 9.3. There was no significant group*time interaction (F2,97 = 0.92, P  = .403, η2partial = 0.02). There were no significant main effects for time (F1,97 = 1.461, P  = .230, η2partial =0.015) or group (F2,97 = 1.08, P  = .342, η2partial = 0.02). Conclusions Findings did not support the use of a single educational intervention video to influence MSKI help-seeking intentions of ROTC trainees. Intentions may already be ingrained such that a single intervention could not influence change. Previous research on concussion reporting indicates that concealment cultures may be systematic and indoctrination of concealment can influence one's reporting intentions. Our sample had already participated in ROTC for 2 years. Future research should evaluate if MSKI help-seeking intentions change over the course of ROTC participation, or even over a military career. [ABSTRACT FROM AUTHOR]

Background Among service members, musculoskeletal injuries threaten military readiness and place a substantial burden on medical and financial resources. Emerging research suggests that service members regularly conceal injuries, especially in training environments. The Reserve Officers' Training Corps (ROTC) is a critical training environment for future U.S. military commissioned officers. Training activities expose cadets to a high risk of injury while in the ROTC. The purpose of this study was to explore injury-reporting behaviors in cadets and factors associated with injury concealment. Materials and Methods We invited Army, Air Force, and Naval cadets from six host universities participating in officer training to complete an online, self-reported survey regarding injury reporting and concealment. Cadets answered questions about pain or injuries experienced during officer training. Survey questions pertained to an injury's anatomic location, onset, severity, functional limitations, and whether or not the injury had been reported. Cadets also selected factors that influenced the decision to report or conceal injuries from predetermined lists in a "choose any" fashion. A series of χ2 tests of independence compared the relationship between injury reporting and other injury characteristics for each individual injury. Results One hundred fifty-nine cadets (121 Army, 26 Air Force, and 12 Naval) completed the survey. Eighty-five cadets disclosed a total of 219 injuries. Two-thirds of injuries (144/219) were concealed. Twenty-six percent of participants (22/85) reported all injuries, whereas the remainder (63/85, 74%) had at least one concealed injury. In relation to injury reporting/concealment, there was a weak association with injury onset (χ21 = 4.24, P  = .04, V  = 0.14), a moderate association with anatomic location (χ212 = 22.64, P  = .03, V  = 0.32), and relatively strong associations with injury severity (χ23 = 37.79, P  < .001, V  = 0.42) and functional limitations (χ23 = 42.91, P  < .001, V  = 0.44). Conclusions Two-thirds of injuries went unreported in this sample of ROTC cadets. Functional limitations, symptom severity, and injury onset may be the largest factors that influence the decision to report or conceal musculoskeletal injuries. This study establishes the foundation for researching injury reporting in cadets and adds to the existing military evidence on the topic. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Hanes, CE, Schilling, BK, Mulvenon, SW, and Radzak, KN. Effects of fatigue on functional movement efficiency in physically active adults. J Strength Cond Res 36(9): 2448–2453, 2022—Functional movement tests to identify faulty movement patterns and compensations have become common place in sports medicine and sport performance; however, this testing is often performed in a rested state, despite athletes being often injured when in a state of neuromuscular fatigue. Therefore, the purpose of our study was to examine the effects of neuromuscular fatigue on a functional movement test in health, physically active adults. Twenty-five adults volunteered for the study (age = 23.3 ± 2.7 years, height = 168.2 ± 9.0 cm, body mass = 72.2 ± 12.5 kg). Subjects completed a prefatigue movement test, an aerobic exercise physically fatiguing protocol, and a postfatigue movement test. Scores were calculated according to compensations present during the tests. Prefatigue (45.1 ± 5.4) to postfatigue (39.9 ± 5.7) overall scores were significantly worse after the fatiguing protocol (p < 0.001, effect size [ES] = 0.9). Prefatigue to postfatigue scores for the 1-Leg Squat, Shoulder, and Cervical subtests were also significantly decreased (p = 0.005, ES = 0.7; p = 0.002, ES = 0.5; p = 0.016, ES = 0.7, respectively). Neuromuscular fatigue affected the functional movement test, demonstrated by a decrease in movement scores, in healthy adults. Clinicians may use the functional movement test to identify potential compensations while their patients are physically fatigued. Then clinicians can implement an injury prevention program to reduce the possible risk of injury. [ABSTRACT FROM AUTHOR]

Neuromuscular fatigue in baseball pitchers has become an important aspect of injury risk. It is imperative to understand howfatigue is manifested to enhance resiliency and mitigate injury risk. Secondarily, collecting data on neuromuscular characteristics of baseball pitchers provides a framework to address these concerns. Using the countermovement jump, this study observed neuromuscular performance during the preseason, midseason, and postseason of a collegiate baseball season with college baseball pitchers. No statistically significant changes were noted in any of the main variables at any testing timepoint (p.0.05). However, several variables, including concentric mean force (ConMF, d50.59) and concentric peak force (ConPF, d=0.59) in addition to eccentric mean force (EccMF, d=0.54) and eccentric mean power (EccMP, d = -0.66), displayed moderate effects from preseason testing to midseason testing. Furthermore, jump height displayed a large negative effect from preseason to midseason (d=-0.89). Secondarily, descriptive data for both concentric and eccentric variables were also determined from the present findings. There were moderate changes in neuromuscular fatigue in Division I collegiate pitchers across a competitive season and has provided descriptive data for neuromuscular characteristics in collegiate baseball pitchers. [ABSTRACT FROM AUTHOR]

Understanding the effects of training in different footwear on sporting performance would be useful to coaches and athletes.Purpose: This study compared the effects of computerized agility training using 3 types of footwear on change-of-direction and balance performance in young adults.Method: Thirty recreationally active young adults (Mage = 22.8 ± 3.1 years; Mheight = 1.71 ± 0.7 m; Mbodymass = 73.4 ± 10.3 kg) were randomly assigned to a 6-week computerized agility training intervention in 1 of 3 footwear groups (n = 10/group): barefoot, minimal footwear, or traditional shoes. Participants had no previous barefoot or minimal-footwear training experience. Dependent variables included change-of-direction test time to completion, Star Excursion Balance Test, and single-leg stability evaluation. Testing was performed at the start of the training program, after 2 weeks, after 4 weeks, and at the end of the training program.Results: No group or time interactions were found for any of the dependent variables. Time main effects were observed for the performance measures of change of direction, Star Excursion, and single-leg-with-eyes-open stability evaluation. Participants improved in all 3 tests as early as 2 weeks into the intervention, with improvements continuing through the entire 6-week intervention.Conclusions: The lack of interaction and footwear effects suggests that agility and balance improvements during foot agility training are independent of footwear in a recreationally active young-adult population. Computerized agility training improves change-of-direction and balance performance within 2 weeks of training implementation. Future studies should consider footwear training effects in different populations, including frail older adults and athletes. [ABSTRACT FROM AUTHOR]

The article discusses research conducted to analyze the top three successful snatch attempts by individual lifters in each weight class at a U.S. National Championship weightlifting meet. After evaluating the lifting techniques of several lifters researchers found that the rearward displacement technique in the drop-under phase in the snatch is not detrimental to performance and actually seems to be a preferred technique in U.S. national level lifters, even in international competitions.

The article discusses a study of the effects of concurrent aerobic endurance and resistance strength exercise on acute metabolic and neuromuscular responses in trained male athletes. Subjects performed bench press and back squat resistance exercises after cycle ergometry or rest. The study looked at number of repetitions until fatigue, finding that endurance ergometry decreased repetitions in back squats. Other topics include heart rate, electromyography, and analysis of variance statistics.

The article discusses research investigating the effect of grip width on electromyographic activity during the upright row (URR), which is a method used to develop the deltoid and upper back musculature. 16 weight-trained men completed two repetitions in the URR with three grip conditions of 50, 100, and 200 percent of the biacromial breadth (BAB). Results from a repeated measures analyses of variance comparing maximal activity in various muscle groups are discussed.

The current U.S. Navy Physical Readiness Test (PRT) measures aerobic fitness and muscular endurance via a 1 1/2 mile run and curl-up/push-up tests, respectively. Nine new modalities were recommended to either replace or supplement the current PRT. Personnel and civilians (N = 179) were recruited from a local Navy base and participated in all modalities (duplicate if possible) over 4 weeks following familiarization sessions. Subjects performed single-leg plank, single-leg wall squat, cadence push-ups, leg/hip dynamometer, standing long jump, and pro-agility test. Cardiovascular modalities were also performed via the 300-yard shuttle, 2-km row, and 5-km bike. Performance in the modalities was correlated to the subjects' existing PRT scores as well as within the new modalities. Although most modalities could not be concretely recommended, the plank and wall squat were eliminated from consideration because of poor reliability scores. The strongest correlation existed between the standing long jump and pro-agility test for the entire sample. Correlation scores were also analyzed by gender. The cardiovascular modalities did not have strong enough scores to elicit a recommendation to replace the 1 Vi mile run, but future considerations for similar testing would be to collect scores for the existing modalities in addition to the proposed modalities. [ABSTRACT FROM AUTHOR]

Background: 1,3-dimethylamylamine is a commonly used ingredient within dietary supplements. Our prior work with this agent indicates a transient increase in blood pressure (systolic in particular) following oral ingestion of a single dosage, but no significant increase in resting blood pressure following chronic ingestion. Moreover, intervention studies involving both two and eight weeks of treatment with finished products containing 1,3-dimethylamylamine indicate minimal or no change in bloodborne markers of health. The present study sought to extend these findings by using a 10-week intervention trial to determine the change in selected markers of health in a sample of men. Methods: 25 healthy men were randomly assigned to either a placebo (n = 13) or to a supplement containing 1,3-dimethylamylamine (n =12) for a period of 10 weeks. Before and after the intervention, resting blood pressure and heart rate were measured, and blood samples were collected for determination of complete blood count, metabolic panel, and lipid panel. Results: No significant differences were noted between conditions for blood pressure (P > 0.05), although systolic blood pressure increased approximately 6 mmHg with the supplement (diastolic blood pressure decreased approximately 4 mmHg). A main effect for time was noted for heart rate (P = 0.016), with values decreasing from pre to post intervention. There were significant main effects for time for creatinine (increased from pre to post intervention; P = 0.043) and alkaline phosphatase (decreased from pre to post intervention; P = 0.009), with no condition differences noted (P > 0.05). There was a significant interaction noted for low density lipoprotein cholesterol (LDL-C) (P = 0.043), with values decreasing in the supplement group from pre to post intervention approximately 7 mg • dL-1 (P = 0.034). No other effects of significance were noted for blood borne variables. Conclusion: These data indicate that a dietary supplement containing 1,3-dimethylamylamine does not result in a statistically significant increase in resting heart rate or blood pressure (although systolic blood pressure is increased -6 mmHg with supplement use). The supplement does not negatively impact bloodborne markers of health. Further study is needed involving a longer intervention period, a larger sample size, and additional measures of health and safety. [ABSTRACT FROM AUTHOR]

Background. Resistance training research has demonstrated positive effects for persons with Parkinson's disease (PD), but the number of acute training variables that can be manipulated makes it difficult to determine the optimal resistance training program. Objective. The purpose of this investigation was to examine the effects of an 8-week resistance training intervention on strength and function in persons with PD. Methods. Eighteen men and women were randomized to training or standard care for the 8-week intervention. The training group performed 3 sets of 5-8 repetitions of the leg press, leg curl, and calf press twice weekly. Tests included leg press strength relative to body mass, timed up-and-go, six-minute walk, and Activities-specific Balance Confidence questionnaire. Results. There was a significant group-by-time effect for maximum leg press strength relative to body mass, with the training group significantly increasing their maximum relative strength (P < .05). No other significant interactions were noted (P > .05). Conclusions.Moderate volume, high-load weight training is effective for increasing lower-body strength in persons with PD. [ABSTRACT FROM AUTHOR]

The article reports on research conducted to investigate the influence of four methods of standing reach height measurement and Vertec jump height measurement against 2 force plate methods of jump displacement determination in athletes while evaluating impulse and flight-time methods. Researchers evaluated 15 athletes. They found that one hand reach with plantar flexion was the method of reach closest to the impulse and flight-time methods and should be used to determine jump displacement.

Background. Resistance training research has demonstrated positive effects for persons with Parkinson's disease (PD), but the number of acute training variables that can be manipulated makes it difficult to determine the optimal resistance training program. Objective. The purpose of this investigation was to examine the effects of an 8-week resistance training intervention on strength and function in persons with PD. Methods. Eighteen men and women were randomized to training or standard care for the 8-week intervention. The training group performed 3 sets of 5-8 repetitions of the leg press, leg curl, and calf press twice weekly. Tests included leg press strength relative to body mass, timed up-and-go, six-minute walk, and Activities-specific Balance Confidence questionnaire. Results. There was a significant group-by-time effect for maximum leg press strength relative to body mass, with the training group significantly increasing their maximum relative strength (P < .05). No other significant interactions were noted (P > .05). Conclusions.Moderate volume, high-load weight training is effective for increasing lower-body strength in persons with PD. [ABSTRACT FROM AUTHOR]

Abstract: Previous investigations have demonstrated leg strength deficits in persons with Parkinson''s disease (PD) as compared to neurologically-normal adults. However, the exact mode of contraction by which strength is assessed may determine how closely such deficits are related to functional performance. The purpose of this study was to better understand the relationship of strength and functional mobility in persons with PD (n = 17, mean H&Y stage = 2.0) via comparison to a group of similar age healthy controls (n = 10) using a multi-joint isometric test of strength and various measures of functional mobility. Tests included isometric leg press maximum force relative to body mass, the Activities-specific Balance Confidence scale (ABC), postural sway under various unilateral stance and visual conditions, and the timed up and go (TUG). Relative force (p = 0.044) and ABC questionnaire mean scores (p < 0.001), showed controls performing better than PD subjects. The control group performed better than the PD group for length of path of the center of pressure except in the eyes closed positions (p < 0.05 for all). TUG time (p = 0.052) was not significantly different between the PD group and healthy controls. Leg press maximum force relative to body mass was however significantly correlated with TUG time (r = −0.68, p = 0.003) in persons with PD. There were no gender differences for any variables. These results suggest that some balance and functional mobility task performances are more worse for persons with mild-to-moderate PD than for neurologically-normal age-matched controls, which may be influenced by lessened lower extremity multi-joint strength. Strength training of the lower extremity utilizing such multi-joint actions may be beneficial for this population. [Copyright &y& Elsevier]

The article reports on the results of research which was conducted to determine the effects a five week unstable surface balance training program had on measures of balance in older adults. Researchers evaluated 19 men and women who were randomly assigned to a control or balance training group. Researchers found that unstable surface training may not be effective in improving balance among people with no balance problem but that it did improve confidence in subjects related to balance.

The article presents a study which discusses the effect of exercise training in the oxidative stress status of people with Parkinson disease. According to the article, resting blood samples were taken from the subjects before and after the program and a supervised exercise was performed twice a week including leg and calf press to gain results. In addition, it states that the scheme had helped lower stress among patients and notes that short-term resistance training can reduce oxidative stress of patients.

The purpose of this brief review is to explain the mechanical relationship between impulse and momentum when resistance exercise is performed in a purposefully slow manner (PS). PS is recognized by ∼10s concentric and ∼4-10s eccentric actions. While several papers have reviewed the effects of PS, none has yet explained such resistance training in the context of the impulse- momentum relationship. A case study of normal versus PS back squats was also performed. An 85kg man performed both normal speed (3 sec eccentric action and maximal acceleration concentric action) and PS back squats over a several loads. Normal speed back squats produced both greater peak and mean propulsive forces than PS action when measured across all loads. However, TUT was greatly increased in the PS condition, with values fourfold greater than maximal acceleration repetitions. The data and explanation herein point to superior forces produced by the neuromuscular system via traditional speed training indicating a superior modality for inducing neuromuscular adaptation. [ABSTRACT FROM AUTHOR]

For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, non-deformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90-155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5-30% (P < 0.05) lower for the centre of the barbell than the ends. Although differences (P < 0.05) in kinetic and potential energy were found between the centre and ends of the bar, differences between total work performed were small ( < 6%; P < 0.05) and no differences were observed for average power (P > 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre. [ABSTRACT FROM AUTHOR]

Individuals with Parkinson's disease (PD) are not only burdened with disease-specific symptoms (i.e., bradykinesia, rigidity, and tremor), but are also confronted with age-associated progressive loss of physical function, perhaps to a greater extent than neurologically normal adults. Suggestions for the inclusion of resistive exercise into treatment to attenuate these symptoms were made over 10 years ago, yet very few well controlled investigations are available. The objective of this review is to establish a clear rationale for the efficacy of resistance training in individuals with PD. Specifically, we highlight musculoskeletal weakness and its relationship to function as well as potential training-induced adaptive alterations in the neuromuscular system. We also review the few resistance training interventions currently available, but limit this review to those investigations that provide a quantitative exercise prescription. Finally, we recommend future lines of inquiry warranting further attention and call to question the rationale behind current exercise prescriptions. The absence of reports contraindicating resistive exercise, the potential for positive adaptation, and the noted benefits of resistance training in other populations may provide support for its inclusion into a treatment approach to PD. © 2007 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Court sports often require more frequent changes of direction (COD) than field sports. Most court sports require 180= turns over a small distance, so COD in such sports might be best evaluated with an agility test involving short sprints and sharp turns. The purposes of this study were to (a) quantify vertical and horizontal force during a COD task, (b) identify possible predictors of court-sport-specific agility performance, and (c) examine performance difference between National Collegiate Athletic Association Division I, II, and III athletes. Twenty-nine collegiate female volleyball players completed a novel agility test, countermovement (CM) and drop jump tests, and an isometric leg extensor test. The number of athletes by division was as follows: I (n = 9), II (n = 11), and III (n = 9). The agility test consisted of 4 5-meter sprints with 3 180= turns, including 1 on a multiaxial force platform so that the kinetic properties of the COD could be identified. One-way analysis of variance revealed that Division I athletes had significantly greater countermovement jump heights than Division III, and the effect size comparisons (Cohen's d) showed large-magnitude differences between Division I and both Divisions II and III for jump height. No other differences in performance variables were noted between divisions, although effect sizes reached moderate values for some comparisons. Regression analysis revealed that CM displacement was a significant predictor of agility performance, explaining approximately 34% of the variance. Vertical force was found to account for much of the total force exerted during the contact phase of the COD task, suggesting that performance in the vertical domain may limit the COD task used herein. This study indicates that individuals with greater CM performance also have quicker agility times and suggests that training predominantly in the vertical domain may also yield improvements in certain types of agility performance. This may hold true even if such agility performance requires a horizontal component. [ABSTRACT FROM AUTHOR]

Previous research has demonstrated that prior exercise may reduce the magnitude of muscle soreness and impaired function (i.e., repeated bout effect [RBE]) observed during subsequent eccentric exercise. Previous investigations have predominantly used research designs that include single-joint exercise performed by untrained individuals. It is unknown how resistance trained individuals respond to novel multi-joint eccentric actions of the upper body and whether prior exercise offers protection. Thirty-one resistance trained men (23.4 ± 3.5 y, 177.2 ± 5.1 cm, 86.4 ± 16.5 kg, mean ± SD) were randomly assigned to repeated bout ([RB] N = 15) or single bout ([CON] N = 16) conditions. Both groups performed 100 eccentric actions of the bench press ([ECC] at 70% concentric 1 repetition maximum) to induce muscle injury. Bilateral maximal isometric force, dynamic exercise performance (e.g., bench press throws), and muscle soreness were measured before, immediately after, and at 24 and 48 hours post-ECC. Total work, percent fatigue, and rating of perceived exertion (ECC) data were collected during ECC. Those assigned to RB condition exhibited less fatigue (9.5 vs. 22.6%) and lower RPE (14.8 vs. 17.1) during ECC. A significant interaction (p < 0.05) was found such that RB individuals experienced less soreness at 24 (6.5 vs. 4.9) and 48 (6.6 vs. 3.9) hours postexercise than the CON condition. No significant group differences (p < 0.05) were found for any measured performance variable. Although soreness, fatigue, and RPE suggest a RBE, this was not found in regards to exercise performance. It appears that in trained men, performing a strenuous high-volume eccentric exercise bout 2 weeks prior to an identical future bout offers no additional amelioration of impaired exercise performance. [ABSTRACT FROM AUTHOR]

Power is an integral aspect of many sports. Although power output of the lower body is often measured during jumping and cycling movements, much less is known about power as pertains to the upper body musculature. Recently, isoinertial methods -- with constant gravitational Load -- of power testing have become common, but little is known of the reliability and criterion validity of these tests as they pertain to sport performance. In addition, the varied methodology makes a lucid model more evasive. The aims of this review are to examine the various methods of assessing upper body power, to establish its role in predicting athletic performance, and to assess the body of literature that has assessed power output of the upper extremities by isoinertial methods. To our knowledge, only two studies on isoinertial upper-body power have shown a direct correlation to sporting ability (Baker, 2001; Baker et al., 2001); therefore, many unanswered questions exist as to the efficacy of these tests as predictors of athletic ability or as a method to track athletes' training over time. From this review we hope to allow the sport coach to assess the overall utility of these tests in terms of availability, safety and external validity. [ABSTRACT FROM AUTHOR]

This investigation estimated the amount of variance in voluntary in vivo muscle performance that can be explained by relative myosin heavy chain (MHC) isoform expression. The role of the relative expression of these proteins in relation to in vitro force and velocity performance is well understood, but the in vivo model is less clear. Twenty-two men and women (mean ± SD age, 27 ± 6 years) performed isometric knee extensor actions in which peak force and rate of force development (RFD) were measured. The results of regression analysis showed that the inclusion of MHC IIb explained a significant (19.9%, p < 0.05) amount of variance in relative peak force (adjusted for muscle mass) and 14.1% of the variance in the first half of the rise phase of the force-time curve (RFD0-50%)(p < 0.1). The addition of MHC I into this model explained a significant (p < 0.05) amount of variance above that accounted for by MHC IIb in RFD (45.4%), RFD0-50% (50.8%), and RFD50-100% (second half of the rise phase of the force-time curve) (37.4%). Since the percentage of MHC IIb is reduced rather quickly with training, these data suggest that peak force may also be affected quickly by training. The percentage of MHC I has a longer course for change with training; therefore, it may be inferred that the greatest changes in RFD variables will likely occur during a longer course. [ABSTRACT FROM AUTHOR]

Military tactical athletes face the unique task of performing physically demanding occupational duties, often while wearing body armor. Forced vital capacity and forced expiratory volume measured using spirometry have been shown to decrease, while wearing plate-carrier style body armor, little is known about the comprehensive effects of wearing body armor on pulmonary function, including lung capacities. Further, the effects of loaded body armor vs. unloaded on pulmonary function are also unknown. Therefore, this study examined how loaded and unloaded body armor affects pulmonary function. Twelve college-aged males performed spirometry and plethysmography under three conditions (basic athletic attire [CNTL], unloaded plate carrier [UNL], and loaded plate carrier [LOAD]). Compared to CNTL, LOAD and UNL conditions significantly reduced functional residual capacity by 14% and 17%, respectively. Compared with CNTL, LOAD condition also showed a small but statistically significant lowered forced vital capacity (P = .02, d = 0.3), a 6% lower total lung capacity (P < .01, d = 0.5), and lowered maximal voluntary ventilation (P = .04, d = 0.4). A loaded plate-carrier style body armor exerts a restrictive effect on total lung capacity, and both loaded and unloaded body armor affects functional residual capacity, which could impact breathing mechanics during exercise. Resulting endurance performance decreases may need to be factored based on the style and loading of body armor, especially for longer-duration operations. [ABSTRACT FROM AUTHOR]

A correction to the article "Computerized Agility Training Improves Change-of-Direction and Balance Performance Independently of Footwear in Young Adults" by Max R. Paquette, Brian K. Schilling, Joshua D. Bravo, Shelby A. Peel, Yuhua Li, and Robert J. Townsend in volume 88, issue 1 of the journal is presented.

Research has focused on the effects of acute strike pattern modifications on lower extremity joint stiffness and running economy (RE). Strike pattern modifications on running biomechanics have mostly been studied while runners complete short running bouts. This study examined the effects of an imposed forefoot strike (FFS) on RE and ankle and knee joint stiffness before and after a long run in habitual rearfoot strike (RFS) runners. Joint kinetics and RE were collected before and after a long run. Sagittal joint kinetics were computed from kinematic and ground reaction force data that were collected during over-ground running trials in 13 male runners. RE was measured during treadmill running. Knee flexion range of motion, knee extensor moment and ankle joint stiffness were lower while plantarflexor moment and knee joint stiffness were greater during imposed FFS compared with RFS. The long run did not influence the difference in ankle and knee joint stiffness between strike patterns. Runners were more economical during RFS than imposed FFS and RE was not influenced by the long run. These findings suggest that using a FFS pattern towards the end of a long run may not be mechanically or metabolically beneficial for well-trained male RFS runners. [ABSTRACT FROM PUBLISHER]

Runners often experience delayed onset muscle soreness (DOMS), especially of the knee extensors, following prolonged running. Sagittal knee joint biomechanics are altered in the presence of knee extensor DOMS but it is unclear how muscle soreness affects lower limb biomechanics in other planes of motion. The purpose of this study was to assess the effects of knee extensor DOMS on three-dimensional (3D) lower limb biomechanics during running. Thirty-three healthy men (25.8 ± 6.8 years; 84.1 ± 9.2 kg; 1.77 ± 0.07 m) completed an isolated eccentric knee extensor damaging protocol to elicit DOMS. Biomechanics of over-ground running at a set speed of 3.35 m s−1±5% were measured before eccentric exercise (baseline) and, 24 h and 48 h following exercise in the presence of knee extensor DOMS. Knee flexion ROM was reduced at 48 h (P = 0.01;d = 0.26), and peak knee extensor moment was reduced at 24 h (P = 0.001;d = 0.49) and 48 h (P < 0.001;d = 0.68) compared to baseline. Frontal and transverse plane biomechanics were unaffected by the presence of DOMS (P > 0.05). Peak positive ankle and knee joint powers and, peak negative knee joint power were all reduced from baseline to 24 h and 48 h (P < 0.05). These findings suggest that knee extensor DOMS greatly influences sagittal knee joint angular kinetics and, reduces sagittal power production at the ankle joint. However, knee extensor DOMS does not affect frontal and transverse plane lower limb joint biomechanics during running. [ABSTRACT FROM AUTHOR]

Athletes often perform intense workouts with short intervals between sessions. The purpose of this investigation was to examine the ability to repeat a high volume chest press workout following a 48 hour rest interval between sessions, as part of a larger intervention. 15 resistance trained men (age 26 ± 4) were recruited from the university population. Subjects performed a one-repetition maximum (1RM) in the bench press exercise on a machine device that allowed independent movement of each arm (Hammer Strength™). Two to four minutes of rest was given between attempts. The highest load lifted in good form was recorded as their 1RM. The following week subjects reported to the lab for two testing sessions 48 hours apart. Power testing was measured by performing bench press throws (BPT) using a weight equivalent to 30% of predetermined machine 1-RM using a ProSpot® device. This apparatus utilizes a self spotting mechanism that contains an electronic sensor, allowing the subject to release the bar at the end range of motion, ensuring a ballistic measure. The subjects laid on a flat bench placed on a uniaxial force plate (Roughdeck) and a position transducer was tethered to the center of the ProSpot® barbell. The first derivative of position with respect to time was taken to calculate velocity of the barbell (Datapak5) and multiplied by force to calculate power (Watts). Data was sampled at 1000Hz and low-pass filtered with a cutoff frequency of 30 Hz. Three BPTs were performed with 90 seconds rest between each effort. The best power output of the 3 BPTs was recorded. Subjects were then given 10 minutes of rest before performing 10 sets of the bench press exercise using a load equal to 60% of 1RM. Each set was performed to a point of momentary muscular failure, using a controlled speed. Subjects were given 90 seconds of rest between each set. No significant differences were observed in power output, 1st set repetitions, total repetitions, mean reps, or volume load from day 1 to day 2 (see table). Although not statistically significant, bench press power was decreased from day 1 to day 2 of testing (2.3%), while bench press endurance measures were slightly increased from day 1 to day 2 of testing (3.2% total reps, 3.6% total volume load). A 48 hour rest interval is sufficient for recovery of power and repeatability of muscular endurance workouts in resistance trained men. Further research is needed to examine the repeatability of shorter or longer rest intervals between workouts. Coaches can design periodized training programs that allow for high-volume muscle group training sessions to be repeated at 48 hours at certain times of the training cycle.Table No Caption Available. [ABSTRACT FROM AUTHOR]

Numerous reports exist concerning relationships between muscle fiber types or myosin heavy chain expression and in vivo human muscle performance. Whereas in vitro high power performances in single muscle cells are most associated with type IIB/X fibers expressing primarily MHC IIb/x, these relationships are not always observed for in vivo volitional performances in humans. Indeed, previous data suggest that high power performances in humans may be correlated with other MHC isoforms (i.e., MHC I or IIa), depending on prior training experience. Comparisons of data are somewhat difficult when different measures of power or different assessments of fiber characteristics are used. Additionally, training experiences of subjects are sometimes difficult to ascertain when comparing different studies. To compare relationships between each MHC isoform and muscle power for subjects with differing training histories. Healthy adult men with a variety of training backgrounds served as subjects for this study (n = 37, [X ± SD] age = 23.3 ± 4.0 yrs., hgt. = 178.4 ± 6.3 cm, BW = 84.8 ± 21.4 kg, % fat = 12.5 ± 6.7 %). Subjects were divided into three subject groups; elite lifters (ELITE; n = 5, 10 yrs. trng experience, 4-5 training sessions·wk-1), moderately weight trained (MOD; n = 27, 1-3 yrs. training experience, 2-3 training sessions·wk-1), and sedentary (SED; n = 5, no training ≥3 yrs.). All subjects performed depth vertical jumps (DVJ) from a height of 0.9 m from which peak power (W) was estimated. Muscle biopsies were obtained from the vastus lateralis m. and analyzed via SDS-PAGE to determine relative expression of myosin heavy chain (MHC) isoform expression. Regression analyses were performed for each subject group between each MHC isoform (i.e., I, IIa, IIb/x) and DVJ peak power (p.81), MOD = MHC type IIb/x (r2>.29), and ELITE = MHC type IIa (r2>.44). The ability to optimize fiber recruitment for a high power movement such as a DVJ is not achieved until large volumes of training have occurred. Untrained individuals most readily recruit the low threshold motor units that contain primarily MHC type I. Moderately trained individuals who still express some MHC IIb/x can recruit these motor units when necessary for activities such as a DVJ. Highly trained individuals who express little or no MHC IIb/x depend preferentially on motor units containing MHC type IIa. This trainingdependent continuum of fiber contributions to high power performance indicates that optimizing high power performance depends on intense, long-term training programs (e.g., >1-3 yrs., >2-3 sessions·wk-1). Funded by grants from the NSCA, the Fed Ex Technology Institute, and GNC, Inc. [ABSTRACT FROM AUTHOR]

Abstract: A prior bout of exercise is well known to confer protection from subsequent eccentric bouts (i.e. repeated bout effect; RBE), which may be fostered through neural adaptations, specifically a shift in the frequency content of the surface electromyogram (EMG). It is currently not clear whether chronically resistance trained men are capable of a RBE driven by neural adaptations. Eleven resistance trained men (23.5±3.4yrs) performed 100 eccentric actions of the barbell bench press exercise, followed by an equivalent bout 14 days later. Indirect markers of muscle damage (i.e. force production, soreness) along with surface EMG were measured before and through 48h of recovery. Median frequency and maximal isometric force demonstrated time main effects (p >0.05), but no RBE. A prior bout of eccentric exercise does not confer a RBE for indirect markers of muscle injury or elicit changes in the frequency content of the EMG signal in resistance trained men. [Copyright &y& Elsevier]

Stone, BL, Ashley, JD, Skinner, RM, Polanco, JP, Walters, MT, Schilling, BK, and Kellawan, JM. Effects of a short-term heat acclimation protocol in elite amateur boxers. J Strength Cond Res 36(7): 1966–1971, 2022—Boxing requires proficient technical and tactical skills coupled with high levels of physiological capacity. Although heat and humidity negatively affect acute exercise performance, short-term exercise training in hot and humid environments can lead to physiological adaptations that enhance exercise performance in both hot and thermoneutral conditions. In highly trained endurance athletes, exercise-induced acclimation can occur in as little as 5 days (known as short-term heat acclimation [STHA]). However, the impact of a 5-day heat acclimation (5-DayHA) in combat athletes, such as elite amateur boxers, is unknown. The aim of the present investigation was to determine whether a 5-DayHA improves aerobic performance in a thermoneutral environment and causes positive physiological adaptations in elite boxers. Seven elite amateur boxers underwent a 5-DayHA protocol, consisting of 60-minute exercise sessions in an environmental chamber at 32 °C and 70% relative humidity. Repeat sprint test (RST) evaluated aerobic performance in a thermoneutral environment 24 hours before and after the 5-DayHA. Presession and postsession hydration status (urine specific gravity) and body mass were assessed. After a 5-DayHA period, boxers significantly improved RST performance (13 ± 7 to 19 ± 7 sprints, d = 0.92, p = 0.03) but not pre-exercise hydration status (1.02 ± 0.01 to 1.01 ± 0.01, d = 0.82, p = 0.07). Therefore, these findings suggest 5-DayHA enhances aerobic performance in elite-level amateur boxers and may provide a viable training option for elite combat athletes. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to investigate the muscle activity in the hamstring muscle and surrounding musculature in weightlifters who performed the leg curl, good morning, glute-ham raise and Romanian deadlift (RDL). Researchers evaluated 12 weight lifters. They found that the semitendinosus is more active than the biceps femoris in all exercises and that the hamstring was maximized in the RDL.

The article reports on research which was conducted to investigate the stability, reliability and precision of several variables and their associations with drop vertical jump displacement in trained men and women. The researchers found that while several of the variables which they evaluated were reliable and precise, many of them had little, if any, association with vertical jump displacement.

The purpose of this study was to determine the acute effects of a spectrum of eccentric loads on force, velocity, and power during the concentric portion of maximal-effort jump squats utilizing a repeated measures design. Thirteen resistance-trained men (age = 22.8 ± 2.9 years, weight = 87.1 ± 11.8 kg, 163.5 ± 28.6 kg squat 1 repetition maximum [1RM]; mean ± SD), who routinely incorporated back squats into their training, participated as subjects in this investigation. Jump squat performance was assessed using 4 experimental conditions. The first of these conditions consisted of an isoinertial load equal to 30% of back squat 1RM. The remaining conditions consisted of jump squats with a concentric load of 30% 1RM, subsequent to the application of experimental augmented eccentric loading (AEL) conditions of 20, 50, and 80% of back squat 1RM, respectively. All subjects performed 2 sets of 1RM of maximum- effort jump squats with all experimental conditions in a counter- balanced sequence. Forty-eight hours after completing the first testing session, subjects repeated the experimental testing protocol to establish stability reliability. Peak performance values for the reliable variables of force, velocity, and power, as well as force and power values obtained at 20-ms intervals during the initial 400 ms of the concentric jump squat range of motion, showed no statistical difference (p > 0.05) across the experimental AEL loads. These results suggest that load-spectrum AEL prior to a 30% 1RM jump squat fails to acutely enhance force, velocity, and power. [ABSTRACT FROM AUTHOR]

Aerobic capacity is an important variable for tactical athletes, with V[Combining Dot Above]O2max being the most direct way of estimating it in a laboratory setting. A mode-specific protocol involving fixed-weight, torso-borne loads was assessed in the current study. On 4 separate days, 15 men (age 22.1 ± 2.7 years, mass 85.1 ± 10.6 kg, height 179.0 ± 7.7 cm) performed a weighted treadmill walking protocol (2 trials) and a nonweighted treadmill running protocol (2 trials). Both the weighted and nonweighted protocols were reliable, with intraclass correlation coefficient values of 0.79 and 0.87, respectively. V[Combining Dot Above]O2peak values from both protocols were highly correlated (r = 0.90, p < 0.01). However, V[Combining Dot Above]O2peak was higher during the nonweighted protocol (t = 7.547, d = 2.47, p < 0.01). Work rate was calculated for both the last completed stage and stage during which participants reached fatigue. Work rates for both protocols on the last completed stage were similar (t = 1.44, d = 0.83, p = 0.17), although the work rate for the final attempted stage was greater for the weighted-walking protocol (t = 5.85, d = 3.60, p < 0.01). These data suggest a weighted-walking V[Combining Dot Above]O2peak that is highly associated with a running V[Combining Dot Above]O2peak. This test may be applied to those who routinely perform torso-borne load carriage, such as tactical athletes. Future weighted-walking protocols should seek achieve higher resolution, especially near the end stage of the test where subjects reach volitional fatigue. Large increases in work rate may not be feasible at the end stages of the test. [ABSTRACT FROM AUTHOR]

Numerous conditions and types of physical activity (e.g., exercise, aging, muscle-related diseases) can influence muscle fiber types and the proteins expressed. To date, muscle fibers can only be characterized by actually obtaining a tissue sample using the invasive muscle biopsy procedure. Mechanomyography (MMG) is the assessment of the vibration properties of contracting skeletal muscle, and has been proposed as a possible non-invasive method for muscle fiber analysis. Therefore, the purpose of this project was to examine the feasibility of using MMG and muscle performance measures to non-invasively assess muscle fiber characteristics. Fifteen men (5 endurance-trained [End], 5 weight-trained [WT], and 5 sedentary [Sed]) provided muscle samples from their vastus lateralis muscle. These samples were analyzed for relative myosin heavy chain protein expression, which is highly correlated with % muscle fiber type areas. Additionally, each subject performed several muscle performance tests, and MMG of the quadriceps was assessed during a knee extension exercise. Multiple regression was used to develop prediction equations for determining relative muscle content of myosin heavy chain (MHC) types I, IIa, and IIx. A combination of MMG and knee extension performance variables estimated types I, IIa, and IIx MHC with approximately 80% accuracy. Although preliminary, these data suggest that muscle performance tests in addition to MMG assessments during a simple muscle performance task (knee extension) can be used to estimate muscle fiber type composition in a healthy male population. Such methods could ultimately be used to non-invasively monitor muscle health and fitness. [ABSTRACT FROM AUTHOR]

Background Bradykinesia and reduced neuromuscular force exist in Parkinson disease. The interpolated twitch technique has been used to evaluate central versus peripheral manifestations of neuromuscular strength in healthy, aging, and athletic populations, as well as moderate to advanced Parkinson disease, but this method has not been used in mild Parkinson disease. This study aimed to evaluate quadriceps femoris rate of force development and quantify potential central and peripheral activation deficits in individuals with Parkinson disease. Methods Nine persons with mild Parkinson Disease (Hoehn & Yahr ≤ 2, Unified Parkinson Disease Rating Scale total score = mean 19.1 (SD 5.0)) and eight age-matched controls were recruited in a cross-sectional investigation. Quadriceps femoris voluntary and stimulated maximal force and rate of force development were evaluated using the interpolated twitch technique. Findings Thirteen participants satisfactorily completed the protocol. Individuals with early Parkinson disease (n = 7) had significantly slower voluntary rate of force development ( p = 0.008; d = 1.97) and rate of force development ratio ( p = 0.004; d = 2.18) than controls (n = 6). No significant differences were found between groups for all other variables. Interpretations Persons with mild-to-moderate Parkinson disease display disparities in rate of force development, even without deficits in maximal force. The inability to produce force at a rate comparable to controls is likely a downstream effect of central dysfunction of the motor pathway in Parkinson disease. [ABSTRACT FROM AUTHOR]

Little research has been done examining the most physically demanding tasks a SWAT officer may perform in the line of duty. Our objective was to analyze the rankings of tasks by SWAT officers based on frequency, difficulty, and importance and assess if training is addressing traits needed for successful task completion. A survey was designed using Qualtrics (Qualtrics Labs Inc). The survey had a demographics section, performance section, and training section. Officers were contacted by phone or e-mail and asked about interest in participating. Officers who agreed were sent the survey. Our results found a strong correlation between frequency of task and importance (r = 0.69, p = 0.001), and a moderate correlation was found between task difficulty and importance (r = 0.37, p = 0.005). Task rankings were averaged across the 3 domains to assess "overall" importance, and the top 3 tasks were assessed for necessary traits for successful performance. Power and strength were determined to be the most important traits for successful performance. Officers ranked the top 2 focuses of their training program in the training section as stamina/muscular endurance and cardiovascular/respiratory endurance. Training programs for SWAT officers should be developed to improve performance of the tasks with the highest "overall" importance. Therefore, a training program should emphasize strength and power improvements while not neglecting other measures of fitness. [ABSTRACT FROM AUTHOR]

Vertical jump (VJ) capability is integral to the level of success attained by individuals participating in numerous sport and physical activities. Knowledge of factors related to jump performance may help with talent identification and/or optimizing training prescription. Although myriad variables are likely related to VJ, this study focused on determining if various lower-body dimensions and/or body composition would explain some of the variability in performance. Selected anthropometric dimensions were obtained from 50 university students (25 men and 25 women) on 2 occasions separated by 48 or 72 hours. Estimated body fat percentage (BF%), height, body weight, hip width, pelvic width, bilateral quadriceps angle (Q-angle), and bilateral longitudinal dimensions of the feet, leg, thigh, and lower limb were obtained. Additionally, participants completed counter-movement VJs. Analysis showed BF% to have the highest correlation with countermovement VJ displacement (r = -0.76, p < 0.001). When examining lower-body dimensions, right-side Q-angle displayed the strongest association with countermovement VJ displacement (r = -0.58, p < 0.001). Regression analysis revealed that 2 different pairs of variables accounted for the greatest variation (66%) in VJ: (a) BF% and sex and (b) BF% and body weight. Regression models involving BF% and lower-body dimensions explained up to 61 % of the variance observed in VJ. Although the variance explained by BF% may be increased by using several lower-body dimensions, either sex identification or body weight explains comparatively more. Therefore, these data suggest that the lower-body dimensions measured herein have limited utility in explaining VJ performance. [ABSTRACT FROM AUTHOR]

Body dimensions may influence various types of physical performance. This study was designed to establish the reliability and precision of bilateral lower-body dimensions using surface anatomic landmarks and either sliding calipers or goniometry. Fifty university students (25 men and 25 women) were measured on 2 separate occasions separated by 48 or 72 hours. A small digital caliper was used to acquire longitudinal dimensions of the feet, whereas a larger broad-blade caliper was used to measure lower-limb, hip, and pelvic dimensions. Quadriceps angle (Q-angle) was determined through surface goniometry. Data for all foot and lower-limb dimensions were both reliable and precise (intraclass correlation coefficient (ICC) ≥0.72, SEM 0.1-0.5 cm). Measures of Q-angle were also reliable and precise (ICC ≥0.85, SEM 0.2-0.4°). Findings from this investigation demonstrate that lower-body dimensions may be reliably and precisely measured through simple practical tests, when surface anatomic landmarks and standardized procedures are used. Although intertester reliability remains to be established, meticulous adherence to specific measurement protocols is likely to yield viable output for lower-body dimensions when more sophisticated methods are unavailable or inappropriate. [ABSTRACT FROM AUTHOR]

Extracellular signal-regulated protein kinase 1/2 (ERK1/2) moderates skeletal muscle growth; however, chronic responses of this protein to unique resistance exercise (RE) paradigms are yet to be explored. The purpose of this investigation was to describe the long-term response of ERK1/2 following circuit weight training (CWT), recreationally weight training (WT), powerlifting (PL) and weightlifting (WL). Independent t-tests were used to determine differences in trained groups compared to sedentary controls. Total ERK1/2 content was lower in PL and WL compared to their controls (p ≤ 0.05). Specific trained groups displayed large (WL: pERK/total-ERK; d = 1.25) and moderate (CWT: total ERK1/2; d = 0.54) effect sizes for altered kinase expression compared to controls. The results indicate ERK1/2 expression is down-regulated after chronic RE in well-trained weightlifters and powerlifters. Lower expression of this protein may be a method in which anabolism is tightly regulated after many years of high-intensity RE. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to examine the effects of footwear on kinetics and lower extremity electromyographic (EMG) activity during the vertical jump (VJ) and standing long jump. The study includes 52 men who performed the two jump types in three footwear conditions including barefoot, minimal shoes and cross-training shoes. The results suggest no acute differences in jump displacement between these footwear conditions.

The article reports on research which was conducted to establish stability reliability of a measure of lower-body anaerobic power, the Kansas squat test (KST), and to compare the KST with the Wingate anaerobic test (WAnT) for lower-body power. Researchers evaluated both tests with 14 resistance trained men. They found that the KST is reliable for resistance-trained men, and that measures of maximum and mean test powers for the KST are highly correlated to those values for the WAnT, but that fatigue rates and lactate responses were not correlated.

The article reports on research which was conducted to compare blood oxidative stress biomarkers in exercise-trained men after three different bouts of exercise of varying intensity and duration, as well as a nonexercise condition. Researchers evaluated 12 men who performed aerobic cycle exercise and cycle splints and collected blood from the men before and after exercise. They found that in exercise-trained men, considering the limitations of their current research design, strenuous bouts of exercise do not result in a significant increase in blood oxidative stress during the one-hour postexercise period.

The article reports on research conducted to investigate the effect 2-nitrooxy ethyl 2-amino 3-methylbutanoate gel had on resistance exercise performance and blood nitrate/nitrite in resistance trained men. Researchers evaluated 14 men. They found that the gel had a minimal effect on nitrate/nitrite and on exercise performance.

Power is critical to muscle performance, specifically in athletic populations. Mitogen-activated protein kinase (MAPK) pathways (extracellular signal-regulated protein kinase (ERK 1/2), p38, and c-Jun NH2-terminal kinase (JNK)) are intracellular signal transduction mechanisms that partially regulate exercise-induced skeletal muscle alterations. These pathways are highly responsive to exercise, but their reaction to high power, multi-joint resistance exercise is yet to be examined. Nine weightlifting-trained men performed 15 sets of three repetitions of a dynamic clean pull exercise at 85% of their one repetition maximum. Vastus lateralis biopsies were obtained prior to (pre) and after the 8th (mid) and 15th set (post) of exercise. Three subjects returned to serve as non-exercising controls for a similar sequence of biopsies (CON). The ratio of phosphorylated MAPK to total MAPK increased significantly for p38 (3.0 fold, p < 0.05) and JNK (2.4 fold, p < 0.05) by the mid biopsy. ERK 1/2 phosphorylation followed a similar trend (2.3 fold) ( p = 0.052). The ratio of phosphorylation to total MAPK did not differ from mid to post biopsy. None of the pathways were phosphorylated above resting in the CON condition ( p > 0.05), and thus the biopsy procedure itself did not account for the entire increase in MAPK phosphorylation during EX. These data indicate MAPK pathways are activated early and remain elevated throughout the duration of high power resistance exercise. These findings help describe the mechanisms partially responsible for chronic adaptations in response to high intensity, high power resistance training in humans. [ABSTRACT FROM AUTHOR]

Trepanowski, JF, Farney, TM, McCarthy, CG, Schilling, BK, Craig, SA, and Bloomer, RJ. The effects of chronic betaine supplementation on exercise performance, skeletal muscle oxygen saturation, and associated biochemical parameters in resistance trained men. J Strength Cond Res 25(12): 3461-3471, 2011-We examined the effects of chronic betaine supplementation on exercise performance and associated parameters in resistance trained men. Men were randomly assigned in a double-blind manner using a crossover design to consume betaine (2.5 g of betaine mixed in 500 ml of Gatorade(R)) or a placebo (500 ml of Gatorade(R)) for 14 days, with a 21-day washout period. Before and after each treatment period, tests of lower- and upper-body muscular power and isometric force were conducted, including a test of upper-body muscular endurance (10 sets of bench press exercise to failure). Muscle tissue oxygen saturation (StO2) during the bench press protocol was measured via near infrared spectroscopy. Blood samples were collected before and after the exercise test protocol for analysis of lactate, nitrate/nitrite (NOx), and malondialdehyde (MDA). When analyzed using a repeated measures analysis of variance, no significant differences were noted between conditions for exercise performance variables (p > 0.05). However, an increase in total repetitions (p = 0.01) and total volume load (p = 0.02) in the 10-set bench press protocol was noted with betaine supplementation (paired t-tests), with values increasing approximately 6.5% from preintervention to postintervention. Although not of statistical significance (p = 0.14), postexercise blood lactate increased to a lesser extent with betaine supplementation (210%) compared with placebo administration (270%). NOx was lower postintervention as compared with preintervention (p = 0.06), and MDA was relatively unchanged. The decrease in StO2 during the bench press protocol was greater with betaine vs. placebo (p = 0.01), possibly suggesting enhanced muscle oxygen consumption. These findings indicate that betaine supplementation results in a moderate increase in total repetitions and volume load in the bench press exercise, without favorably impacting other performance measures. [ABSTRACT FROM AUTHOR]