Hillary A. Plummer

Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch

Abstract The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic–hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

Muscle activation patterns of the upper and lower extremity during the windmill softball pitch.

Oliver, GD, Plummer, HA, and Keeley, DW. Muscle activation patterns of the upper and lower extremity during the windmill softball pitch. J Strength Cond Res 25(6): 1653-1658, 2011—Fast-pitch softball has become an increasingly popular sport for female athletes. There has been little research examining the windmill softball pitch in the literature. The purpose of this study was to describe the muscle activation patterns of 3 upper extremity muscles (biceps, triceps, and rhomboids [scapular stabilizers]) and 2 lower extremity muscles (gluteus maximus and medius) during the 5 phases of the windmill softball pitch. Data describing muscle activation were collected on 7 postpubescent softball pitchers (age 17.7 ± 2.6 years; height 169 ± 5.4 cm; mass 69.1 ± 5.4 kg). Surface electromyographic data were collected using a Myopac Jr 10-channel amplifier (RUN Technologies Scientific Systems, Laguna Hills, CA, USA) synchronized with The MotionMonitor™ motion capture system (Innovative Sports Training Inc, Chicago IL, USA) and presented as a percent of maximum voluntary isometric contraction. Gluteus maximus activity reached (196.3% maximum voluntary isometric contraction [MVIC]), whereas gluteus medius activity was consistent during the single leg support of phase 3 (101.2% MVIC). Biceps brachii activity was greatest during phase 4 of the pitching motion. Triceps brachii activation was consistently >150% MVIC throughout the entire pitching motion, whereas the scapular stabilizers were most active during phase 2 (170.1% MVIC). The results of this study indicate the extent to which muscles are activated during the windmill softball pitch, and this knowledge can lead to the development of proper preventative and rehabilitative muscle strengthening programs. In addition, clinicians will be able to incorporate strengthening exercises that mimic the timing of maximal muscle activation most used during the windmill pitching phases.

The relationship between gluteal muscle activation and throwing kinematics in baseball and softball catchers.

Abstract Plummer HA and Oliver GD. The relationship between gluteal muscle activation and throwing kinematics in baseball and softball catchers. J Strength Cond Res 28(1): 87–96, 2014—The purpose of this study was to determine the relationship between gluteal muscle activation and pelvis and trunk kinematics when catchers throw to second base. Forty-two baseball and softball catchers (14.74 ± 4.07 years; 161.85 ± 15.24 cm; 63.38 ± 19.98 kg) participated in this study. Muscle activity of the bilateral gluteus maximus and medius as well as pelvis and trunk kinematics throughout the throwing motion were analyzed. It was discovered that at foot contact, there were 2 significant inverse relationships between stride leg gluteus maximus activity and pelvis axial rotation (r = −0.31, r2 = 0.10, p = 0.05), and between trunk axial rotation and pelvis lateral flexion (r = −0.34, r2 = 0.12, p = 0.03). In addition, at foot contact, a significant positive relationship between the drive leg (throwing arm side) and trunk flexion (r = 0.33, r2 = 0.11, p = 0.04) was present. The results of this study provide evidence of gluteal activation both concentrically and eccentrically, in attempt to control the pelvis and trunk during the throwing motion of catchers. The gluteal muscles play a direct role in maintaining the stability of the pelvis, and catchers should incorporate strengthening of the entire lumbopelvic-hip complex into their training regimen. Incorporating concentric and eccentric gluteal exercises will help to improve musculoskeletal core stability, thereby assisting in upper extremity injury prevention.

Electromyographic examination of selected muscle activation during isometric core exercises.

Objective:The purpose of the current study was to quantitatively examine the muscle activations of 3 common isometric core exercises (abdominal bridge, single-leg abdominal bridge, and superman) along with a newly introduced isometric exercise (flying squirrel) and determine if muscle activations differed among the exercises. Design:The design was a comparison study. Setting:An athletic training classroom laboratory was where all data collections occurred. Participants:Thirty healthy collegiate graduate students (age, 23.4 ± 1.4 year; height, 171.3 ± 10.3 cm; mass, 73.3 ± 16.2 kg), regardless of sex, consented to participate. Independent Variable:The independent variable was the muscle selected. Main Outcome Measures:The main outcome measures or dependent variables were the muscle activation reported as percent of maximum voluntary isometric contraction during each exercise. Results:Results revealed that the multifidi produced the greatest muscle activity in all exercises, and the single-leg abdominal bridge exercise produced greater muscle activation than the general abdominal bridge exercise (P < 0.025). Conclusions:The findings of this study demonstrate that any of these exercises may be a part of a core stability program. In addition, these findings may be incorporated into an isometric core exercise program to supplement a currently implemented isometric core exercise program.

Quantitative analysis of kinematics and kinetics of catchers throwing to second base

Abstract The catcher has the most demanding position in the games of baseball and softball with no regulations on how many throws they make during game. It was the purpose of this study to describe the kinematics and kinetics of the throwing motion in catchers when throwing down to second base. It was hypothesised that younger and older catchers would display significantly different throwing kinematics and kinetics. Thirty-eight baseball and softball catchers volunteered to participate. Twenty participants were considered younger (aged 9–14, 10.95 ± 1.76 years, 151.11 ± 15.64 cm, 47.94 ± 18.84 kg) and 18 were deemed the older group (aged 15–23, 18.11 ± 2.61 years, 170.91 ± 8.67 cm, 74.88 ± 10.74 kg). Participants received a pitch and completed five accurate throws to second base in full catching gear. The average ball speed of the older catchers was 21 ± 3.58 meters per second (47 ± 8.02 mph) while the younger catchers averaged 17.2 ± 4.0 meters per second (38.6 ± 8.96 mph). Older catchers had greater shoulder elevation at ball release and significantly greater shoulder external rotation at foot contact and shoulder maximum external rotation than younger catchers. It is clear that chronological age plays a role in the throwing mechanics observed in catchers throwing down to second base, however the effects of these differences are not fully understood (i.e., skeletal maturity, experience, strength).

Gluteus medius and scapula muscle activations in youth baseball pitchers.

Abstract Oliver, GD, Weimar, WH, and Plummer, HA. Gluteus medius and scapula muscle activations in youth baseball pitchers. J Strength Cond Res 29(6): 1494–1499, 2015—The baseball pitching motion is a total kinetic chain activity that must efficiently use both the upper and lower extremity. Of particular importance is the scapular motion, which is critical for humeral positioning and proper alignment of shoulder musculature. It was hypothesized that scapular stability is enhanced by pelvic girdle stability. Therefore, it was the purpose of this study to determine the muscle activations of selected pelvic and scapular stabilizing muscles during a fastball pitch in youth baseball pitchers. Twenty youth baseball pitchers (age: 11.3 + 1.0 years; height: 152.4 + 9.0 cm; weight: 47.5 + 11.3 kg) were recorded throwing 4-seam fastballs for strikes. Data revealed moderate (20–39% maximum voluntary isometric contraction [MVIC]) to moderately strong (>40% MVIC) activation of the ipsilateral (throwing arm side) gluteus medius, upper trapezius, and serratus anterior throughout phases 2 (maximum shoulder external rotation to ball release) and 3 (ball release to maximum shoulder internal rotation). Moderately strong activation (>40% MVIC) of the upper trapezius and serratus anterior was noted during phases 2 and 3 of the pitching motion. Pearsons product-moment correlation revealed significant relationships between bilateral gluteus medius and the force couples about the scapula during all 3 phases of the pitching motion. The results of this study provide important data that improve the understanding of the muscular relationship between the pelvic and scapular stabilizers during the fastball pitch. Training and rehabilitation programs should consider focusing on lumbopelvic-hip and scapular muscle strengthening as well as coordinated strengthening of the pelvic and scapular stabilizers, in baseball pitchers.

A Kinematic and Kinetic Analysis of Drop Landings in Military Boots

Objective The purpose of this study was to examine knee valgus in drop landings during three different footwear conditions and to examine the ground reaction forces exhibited during the drop landing in the three different footwear conditions. Methods Sixteen male and female Reserve Officer Training Corps (ROTC) university undergraduate cadets (21±3 yrs, 79±12 kg, and 172±10 cm) volunteered to participate in the study. Kinematic data were collected while participants performed drop landings in three conditions: bare feet, tennis shoes, and issued military boots. Results Significant differences among footwear for ground reaction forces (bare feet: 1646 ±359%, tennis shoe: 1880±379%, boot: 1833±438%; p < 0.05) were found, while there was no significant difference in knee valgus among footwear. Conclusions Though footwear conditions did not affect knee valgus, they did affect ground reaction forces. Participants in this study had yet to receive any military training on how to land properly from a specified height. Further research should be completed to analyze the kinematics and kinetics of the lower extremity during different landing strategies implemented by trained military personnel in order to better understand injury mechanisms of drop landings in this population. It is likely that injury prevention landing techniques would be beneficial if these were employed by the military and not just in the sporting community.

Effects of a Simulated Game on Upper Extremity Pitching Mechanics and Muscle Activations Among Various Pitch Types in Youth Baseball Pitchers.

BACKGROUND Throwing requires proper stability and orientation of the pelvis and scapula for efficient energy transfer during pitching. Fatigue of the pelvis and scapular musculature throughout the course of a game can impair pitching performance, and place excessive demands on the throwing arm leading to injury. The purpose of this study was to examine differences in pelvis, torso, and upper extremity pitching mechanics and muscle activations between the fastball, change-up, and curveball pitches in youth baseball pitchers following a simulated game. METHODS Fourteen youth baseball pitchers with no history of injury participated. Pitching mechanics were collected using an electromagnetic tracking system. Surface electromyography data were collected on the bilateral gluteus medius and maximus; and throwing arm side latissimus dorsi, lower trapezius, upper trapezius, and serratus anterior. Participants were instructed to throw maximum effort pitches during a simulated game that provided random game situations similar to those that occur in competition. Participants were limited to 85 pitches based on age-restricted pitch counts. Data from 3 fastballs, curveballs, and change-ups thrown in the first and last innings were selected for analysis. RESULTS Repeated measures multivariate analyses of variance revealed that neither pitch type nor the effect of a simulated game resulted in statistically significant changes in pitching mechanics (F(10,600)=0.55, P=0.85), or muscle activations (pelvic: F(4,195)=0.07, P=0.85; scapular: F(4,118)=0.09, P=0.52). CONCLUSIONS The principle findings of this study revealed that pitching to the age-restricted pitch count limit did not result in altered pitching mechanics or muscle activations, and no differences occurred between the 3 pitches. These results support previous research that indicate the curveball pitch is no more dangerous for youth than the other pitches commonly thrown. This is supported by the pitchers ability to maintain a proper arm slot during all 3 pitches and indicates that they are obtaining the spin on the ball from their grip and not by altering upper extremity mechanics. LEVEL OF EVIDENCE Level 5.BACKGROUND Throwing requires proper stability and orientation of the pelvis and scapula for efficient energy transfer during pitching. Fatigue of the pelvis and scapular musculature throughout the course of a game can impair pitching performance, and place excessive demands on the throwing arm leading to injury. The purpose of this study was to examine differences in pelvis, torso, and upper extremity pitching mechanics and muscle activations between the fastball, change-up, and curveball pitches in youth baseball pitchers following a simulated game. METHODS Fourteen youth baseball pitchers with no history of injury participated. Pitching mechanics were collected using an electromagnetic tracking system. Surface electromyography data were collected on the bilateral gluteus medius and maximus; and throwing arm side latissimus dorsi, lower trapezius, upper trapezius, and serratus anterior. Participants were instructed to throw maximum effort pitches during a simulated game that provided random game situations similar to those that occur in competition. Participants were limited to 85 pitches based on age-restricted pitch counts. Data from 3 fastballs, curveballs, and change-ups thrown in the first and last innings were selected for analysis. RESULTS Repeated measures multivariate analyses of variance revealed that neither pitch type nor the effect of a simulated game resulted in statistically significant changes in pitching mechanics (F(10,600)=0.55, P=0.85), or muscle activations (pelvic: F(4,195)=0.07, P=0.85; scapular: F(4,118)=0.09, P=0.52). CONCLUSIONS The principle findings of this study revealed that pitching to the age-restricted pitch count limit did not result in altered pitching mechanics or muscle activations, and no differences occurred between the 3 pitches. These results support previous research that indicate the curveball pitch is no more dangerous for youth than the other pitches commonly thrown. This is supported by the pitchers ability to maintain a proper arm slot during all 3 pitches and indicates that they are obtaining the spin on the ball from their grip and not by altering upper extremity mechanics. LEVEL OF EVIDENCE Level 5.

Biomechanical Comparison of Three Perceived Effort Set Shots in Team Handball Players.

Abstract Plummer, HA, Gascon, SS, and Oliver, GD. Biomechanical comparison of three perceived effort set shots in team handball players. J Strength Cond Res 31(1): 80–87, 2017—Shoulder injuries are prevalent in the sport of team handball; however, no guidelines currently exist in the implementation of an interval throwing protocol for players returning from an upper extremity injury. These guidelines exist for the sport of baseball, but team handball may present additional challenges due to greater ball mass that must be accounted for. The purpose of this study was to examine kinematic differences in the team handball set shot at 50, 75, and 100% effort which are common throwing intensities in throwing protocols. Eleven male team handball players (23.09 ± 3.05 years; 185.12 ± 8.33 cm; 89.65 ± 12.17 kg) volunteered. An electromagnetic tracking system was used to collect kinematic data at the pelvis, trunk, scapula, and shoulder. Kinematic differences at the shoulder, trunk, and pelvis were observed across effort levels throughout the set shot with most occurring at ball release and maximum internal rotation. Significant differences in ball speed were observed between all 3 effort level shots (p < 0.001). Team handball players are able to gauge the effort at which they shoot; however, it cannot be assumed that these speeds will be at a certain percentage of their maximum. The results of this study provide valuable evidence that can be used to prepare a team handball player to return to throwing activities.

Electromyographic Analysis of Traditional and Kinetic Chain Exercises for Dynamic Shoulder Movements.

Abstract Oliver, GD, Plummer, HA, and Gascon, SS. Electromyographic analysis of traditional and kinetic chain exercises for dynamic shoulder movements. J Strength Cond Res 30(11): 3146–3154, 2016—Proper utilization of the kinetic chain allows for efficient kinetic energy transfer from the proximal segments to the distal segments. The aims of this study were to describe muscle activations in 4 kinetic chain prethrowing exercises and compare these muscle activations with 3 traditional resistance-band exercises. Twenty-six healthy college students (22.9 ± 3.4 years; 172.2 ± 8.6 cm; 74.2 ± 16.3 kg), regardless of gender, participated. Surface electromyographic data were recorded for selected pelvic and scapular musculature while subjects performed the exercises. The exercises included airplane (single-leg balance with weight-bearing hip flexed to 90° and non–weight-bearing hip extended) while performing alternating repetitions of external and internal shoulder rotation, lunge, Get Up, single-leg balance, and resistance band I, T, and Y. A repeated-measures analysis of variance, with a factor of exercise (8 different levels), was used. Post hoc analyses were used for each muscle to determine the statistically significant differences between exercises. The results reveal the greatest activation occurred during the 2 airplane exercises than all the other exercises. The results of this study help to establish surface electromyographic data for selected pelvis and scapula musculature during a series of kinetic chain and resistance-band exercises. Understanding the muscle activations during these exercises can assist clinicians and coaches in choosing the appropriate exercises to implement for individuals involved in dynamic shoulder movement.