Test Re-Test Reliability of Four Versions of the 3-Cone Test in Non-Athletic Men.

Until recently, measurement and evaluation in sport science, especially agility testing, has not always included key elements of proper test construction. Often tests are published without reporting reliability and validity analysis for a specific population. The purpose of the present study was to examine the test re-test reliability of four versions of the 3-Cone Test (3CT), and provide guidance on proper test construction for testing agility in athletic populations. Forty male students enrolled in classes in the Department of Physical Education at a mid-Atlantic university participated. On each of test day participants performed 10 trials. In random order, they performed three trials to the right (3CTR, standard test), three to the left (3CTL), and two modified trials (3CTAR and 3CTAL), which included a reactive component in which a visual cue was given to indicate direction. Intra-class correlation coefficients (ICC) indicated a moderate to high reliability for the four tests, 3CTR 0.79 (0.64-0.88, 95%CI), 3CTL 0.73 (0.55-0.85), 3CTAR 0.85(0.74-0.92), and 3CTAL 0.79 (0.64-0.88). Small standard error of the measurement (SEM) was found; range 0.09 to 0.10. Pearson correlations between tests were high (0.82-0.92) on day one as well as day two (0.72-0.85). These results indicate each version of the 3-Cone Test is reliable; however, further tests are needed with specific athletic populations. Only the 3CTAR and 3CTAL are tests of agility due to the inclusion of a reactive component. Future studies examining agility testing and training should incorporate technological elements, including automated timing systems and motion capture analysis. Such instrumentation will allow for optimal design of tests that simulate sport-specific game conditions.

Comparison of the "Tall and Fall" Versus "Drop and Drive" Pitching Styles: Analysis of Major League Baseball Pitchers During a Single Season.

Background: Previous research has documented the proportion of "tall and fall" (TF) and "drop and drive" (DD) pitching styles among Major League Baseball (MLB) pitchers who underwent ulnar collateral ligament reconstruction (UCLR). The proportion of these 2 styles among all MLB pitchers remains unknown. Purpose: To determine the proportion of the TF and DD pitching styles in all rostered MLB pitchers during a single season as well as the proportion of TF and DD pitchers who sustained an upper extremity (UE) injury and those who underwent UCLR. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Pitcher demographic characteristics from the 2019 MLB season and pitching information were obtained via open-access sources. Two-dimensional video analysis was used to categorize the included pitchers into TF and DD groups. Statistical comparisons and contrasts were made using 2-tailed t tests, chi-square tests, and Pearson correlation analyses as appropriate. Results: Of the 660 MLB rostered pitchers in 2019 (age, 27.39 ± 3.51 years; body mass index, 26.34 ± 2.47 kg/m2; fastball velocity, 150.49 ± 3.99 kph [93.51 ± 2.48 mph]), 412 (62.4%) pitchers used the TF style and 248 (37.6%) pitchers used the DD style. Significantly more UE injuries were seen in the TF group compared with the DD group (112 vs 38 injuries, respectively; P < .001). Twelve pitchers underwent UCLR (TF, 10; DD, 2), representing a 1.8% UCLR rate among all pitchers. This was a second surgery for 2 pitchers, both of whom used the TF pitching style. Significantly more pitchers in the TF group than the DD group had undergone UCLR before 2019 (135 vs 56 pitchers, respectively; P = .005). Conclusion: The results of the present study demonstrated a higher prevalence of both UE injury and prior UCLR in TF pitchers. Further research is needed to explore the potential association between pitching style and UE injury.

Retrospective Analysis of Ulnar Collateral Ligament Reconstructions in Major League Baseball Pitchers: A Comparison of the "Tall and Fall" Versus "Drop and Drive" Pitching Styles.

Background: Previous pilot research has investigated differences in elbow valgus torque between the "tall and fall" (TF) and "drop and drive" (DD) pitching styles. Whether one of these pitching styles is associated with a greater rate of ulnar collateral ligament reconstruction (UCLR) is currently unknown. Purpose: To determine the proportion of Major League Baseball (MLB) pitchers using the TF and DD pitching styles who underwent UCLR over a 10-year period. Study Design: Cross-sectional study; Level of evidence, 3. Methods: The demographic characteristics of pitchers who underwent UCLR between 2007 and 2017 were obtained via the open-source database MLB Player Analysis Tommy John Surgery List. Other information, such as previous UCLR and pitching videos and graphics, was obtained from other open-source databases. A comprehensive, 2-dimensional, kinesiology-based multicomponent definition of each pitching style was formulated and used to categorize the included pitchers into the TF and DD groups. Statistical comparisons and contrasts were made using chi-square and Pearson correlation tests. Results: Included were 223 MLB pitchers (mean ± SD age, 27.5 ± 3.6 years; body mass index [BMI], 27.6 ± 2.2; throwing velocity, 92.9 ± 2.6 mph [149.5 ± 4.2 km/h]) who underwent UCLR between 2007 and 2017. Of these pitchers, 162 were categorized as TF pitchers (72.6%) and 61 as DD pitchers (27.4%). Pitching velocity for injured pitchers was significantly correlated to BMI (P < .001). We found no significant associations of pitching style with year of UCLR (P = .941), BMI (P = .549), age (P = .647), handedness (P = .501), or average pitch velocity (P = .921). Conclusion: The study findings demonstrated that a higher proportion of UCL-injured MLB pitchers (72.6%) used the TF pitching style. Further research is needed to explore the potential association between pitching style and UCL injury.

Enhancement of Skeletal Muscle in Aged Rats Following High-Intensity Stretch-Shortening Contraction Training.

Exercise is the most accessible, efficacious, and multifactorial intervention to improve health and treat chronic disease. High-intensity resistance exercise, in particular, also maximizes skeletal muscle size and strength-outcomes crucial at advanced age. However, such training is capable of inducing muscle maladaptation when misapplied at old age. Therefore, characterization of parameters (e.g., mode and frequency) that foster adaptation is an active research area. To address this issue, we utilized a rodent model that allowed training at maximal intensity in terms of muscle activation and tested the hypothesis that muscles of old rats adapt to stretch-shortening contraction (SSC) training, provided the training frequency is sufficiently low. At termination of training, normalized muscle mass (i.e., muscle mass divided by tibia length) and muscle quality (isometric force divided by normalized muscle mass) were determined. For young rats, normalized muscle mass increased by ∼20% regardless of training frequency. No difference was observed for muscle quality values after 2 days versus 3 days per week training (0.65 ± 0.09 N/mg/mm vs. 0.59 ± 0.05 N/mg/mm, respectively). For old rats following 3 days per week training, normalized muscle mass was unaltered and muscle quality was 30% lower than young levels. Following 2 days per week training at old age, normalized muscle mass increased by 17% and muscle quality was restored to young levels. To investigate this enhanced response, oxidative stress was assessed by lipid peroxidation quantification. For young rats, lipid peroxidation levels were unaltered by training. With aging, baseline levels of lipid peroxidation increased by 1.5-fold. For old rats, only 2 days per week training decreased lipid peroxidation to levels indistinguishable from young values. These results imply that, appropriately scheduled high-intensity SSC training at old age is capable of restoring muscle to a younger phenotype in terms of lipid peroxidation levels and muscle quality.

Age-dependent Muscle Adaptation after Chronic Stretch-shortening Contractions in Rats.

Age-related differences in contraction-induced adaptation have been well characterized especially for young and old rodent models but much less so at intermediate ages. Therefore, additional research is warranted to determine to what extent alterations in adaptation are due to maturation versus aging per se. The purpose of our study was to evaluate muscles of Fisher 344XBrown Norway rats of various ages following one month of exposure to stretch-shortening contractions (SSCs). With exposure, muscles mass increased by ~10% for 27 and 30 month old rats vs. ~20% for 3 and 6 month old rats (P < 0.05). For 3 month old rats, maximum isometric force and dynamic peak force increased by 22 ± 8% and 27 ± 10%, respectively (P < 0.05). For 6 month old rats, these forces were unaltered by exposure and positive work capacity diminished by 27 ± 2% (P = 0.006). By 30 months of age, age-related deficits in maximum isometric force, peak force, negative work, and positive work were apparent and SSC exposure was ineffective at counteracting such deficits. Recovery from fatigue was also tested and exposure-induced improvements in fatigue recovery were indicated for 6 month old rats and to a lesser extent for 3 month old rats whereas no such effect was observed for older rats. Alterations in fatigue recovery were accompanied by evidence of substantial type IIb to IIx fiber type shifting. These results highlight the exceptional adaptive capacity for strength at a young age, the inclination for adaptation in fatigue recovery at early adulthood, and diminished adaptation for muscle performance in general beginning at late adulthood. Such findings motivate careful investigation to determine appropriate SSC exposures at all stages of life.

Impact of stretch-shortening cycle rest interval on in vivo muscle performance.

INTRODUCTION: Overuse and overtraining models have implicated both metabolic and mechanical disturbances as contributors to muscle damage and performance decrement but have produced equivocal results. The purpose of the present study was to investigate the impact of rest interval between sets of stretch-shortening cycles (SSC) on static and dynamic muscle performance METHODS: Animals were randomly assigned to groups (N = 8 per group) of 10-s, 1-min, or 5-min rest between sets of isometric contractions (10-s, 1-min, or 5-min CON), or SSC (10-s, 1-min, or 5-min INJ). The dorsiflexor muscles were exposed in vivo to either seven sets of 10 SSC (500 degrees . s) or seven sets of isometric contractions. Performance was characterized by isometric exertions and positive, negative, and net work, at pretest, during the sets of SSC, and 48 h postexposure RESULTS: The isometric force at 48 h after the 10-s and 5-min INJ groups were statistically different from the 1-min group (P < 0.05), whereas there was no difference in the CON groups. Negative work of the INJ groups were statistically lower at 48 h than pretest values (P < 0.05), whereas there was no change in positive work. Of the real-time parameters, there was a difference in minimum force and positive work (P < 0.05) with treatment with the 10-s INJ group being most affected. CONCLUSION: SSC conducted at shorter work-rest cycles resulted in a more profound isometric force decrement 48 h postexposure, and in real-time changes in isometric prestretch force and positive work. These results indicate that short rest intervals between athletic or vocational tasks of heightened physical exertion (i.e., high intensity) may adversely affect performance and increase injury susceptibility.

Volitional Weight-Lifting in Rats Promotes Adaptation via Performance and Muscle Morphology prior to Gains in Muscle Mass.

Investigation of volitional animal models of resistance training has been instrumental in our understanding of adaptive training. However, these studies have lacked reactive force measurements, a precise performance measure, and morphological analysis at a distinct phase of training - when initial strength gains precede muscle hypertrophy. Our aim was to expose rats to one month of training (70 or 700 g load) on a custom-designed weight-lifting apparatus for analysis of reactive forces and muscle morphology prior to muscle hypertrophy. Exclusively following 700 g load training, forces increased by 21% whereas muscle masses remained unaltered. For soleus (SOL) and tibialis anterior (TA) muscles, 700 g load training increased muscle fiber number per unit area by ∼20% and decreased muscle fiber area by ∼20%. Additionally, number of muscle fibers per section increased by 18% for SOL muscles. These results establish that distinct morphological alterations accompany early strength gains in a volitional animal model of load-dependent adaptive resistance training.

Effects of exercise and creatine on myosin heavy chain isoform composition in patients with Charcot-Marie-Tooth disease.

It is not known whether myosin heavy chain (MHC) content changes in response to exercise training or creatine supplementation in subjects with Charcot-Marie-Tooth disease (CMT). Based on previous data, we hypothesized that resistance exercise and creatine would increase the percentage of type I MHC composition in the vastus lateralis muscle and that myosin isoform changes would correlate with improved chair rise-time in CMT subjects. To test this hypothesis, 18 CMT subjects were randomly assigned to either a placebo or creatine group. All subjects performed a 12-week, home-based, moderate-intensity resistance training program. Chair rise-time was measured before and after the training program. Muscle biopsies were obtained from the vastus lateralis before and after the 12-week program. Gel electrophoresis showed a significant decrease (approximately 30%) in MHC type I in CMT subjects given creatine supplementation when compared with placebo. There was a nonsignificant increase in both MHC type IIa (approximately 23%) and MHC type IIx (approximately 7%) in CMT subjects given creatine. Reduced MHC type I content and increased MHC type IIa content correlated with faster chair rise-times (i.e., improved muscle performance). The training-induced change in MHC IIa content was inversely correlated with chair rise-time in CMT subjects given creatine. When the two subject groups were combined, there was a linear, negative relationship between the change in MHC type IIa content and chair rise-time after training and a positive relationship between the training-induced change in MHC type I content and chair rise-time. These data suggest that improved function (chair rise-time) was associated with a lower level of MHC type I and increased MHC type IIa composition. Furthermore, the data are consistent with the hypothesis that creatine supplementation alters MHC composition in CMT patients undergoing resistance training and that MHC changes associated with creatine supplementation can improve muscle function.

Resistance training effectiveness in patients with Charcot-Marie-Tooth disease: recommendations for exercise prescription.

OBJECTIVES: To determine the effects of a 12-week, home-based resistance exercise program on strength, body composition, and activities of daily living (ADLs) in men and women with Charcot-Marie-Tooth (CMT) disease and to design an ADL-based resistance exercise prescription template. DESIGN: Double-blind, placebo-controlled study. SETTING: Testing in a university setting; exercise in patients' homes. PARTICIPANTS: Twenty CMT patients who volunteered. INTERVENTION: Subjects progressively strength trained at home 3 d/wk for 12 weeks. MAIN OUTCOME MEASURES: Timed ADLs, isometric strength, and body composition. RESULTS: Absolute strength was greater in men with CMT in only 4 of 10 baseline measures (P<.05), but not when strength was normalized by lean mass. Training compliance was 87% with no gender differences. At baseline, women had 80% of normal strength in 4 of 10 measures, whereas men did not achieve 80% of normal strength in any measure. After training, women had 80% of normal strength in 8 of 10 measures, whereas men only had 80% of normal strength in 1. Training volumes and strength change scores showed no gender differences. ADLs improved after training with no gender differences (P<.05). An exercise prescription template was developed by using chair-rise time to estimate starting weights for lower body and supine rise for upper body. CONCLUSIONS: Resistance training improved strength and ADLs equally in men and women. We designed an exercise prescription recommendation, based on ADL performance.

Resistance training exercise and creatine in patients with Charcot-Marie-Tooth disease.

Resistance exercise and creatine supplementation independently improve strength and function in patients with certain neuromuscular diseases. The purpose of this study was to examine the effects of resistance training with and without creatine supplementation on muscle, strength, and function in patients with Charcot-Marie-Tooth (CMT) disease. Twenty patients with CMT consumed 5 g/day creatine or placebo while participating in resistance training for 12 weeks. Energy metabolites, muscle fiber type and size, strength, and timed activities of daily living were measured before and after training. There were no differences between creatine or placebo groups for any outcome. For the groups combined, exercise training increased type I muscle fiber diameter (48.2 +/- 14.2 microm vs. 55.4 +/- 14.8 microm), strength, and activities of daily living (ADL) times. Thus, patients respond to resistance training with muscle fiber adaptations, and improvements in strength and function. Creatine was not beneficial.