Gretchen D. Oliver

GLUTEAL MUSCLE GROUP ACTIVATION AND ITS RELATIONSHIP WITH PELVIS AND TORSO KINEMATICS IN HIGH-SCHOOL BASEBALL PITCHERS

Oliver, GD and Keeley, DW. Gluteal muscle group activation and its relationship with pelvis and torso kinematics in high-school baseball pitchers. J Strength Cond Res 24(11): 3015-3022, 2010-The purpose of this study was to examine the activation patterns of the gluteal muscle group and their relationship to pelvis and torso kinematics throughout the high-school pitching motion. A single group, repeated-measures design was used to collect gluteus maximus and gluteus medius muscle activity through surface electromyography for the preferred and nonpreferred sides during the various phases of the pitching motion. In addition, data describing the kinematics of the pelvis and torso were collected at foot contact, maximum shoulder external rotation, ball release, and maximum shoulder internal rotation. For all pitchers, preferred gluteus maximus activity was observed to be in excess of 100% of their maximum voluntary isometric contraction throughout the stride and arm-cocking phases of the pitching motion. The observed means for the preferred gluteus medius, nonpreferred gluteus maximus, and nonpreferred gluteus medius, although different in magnitude, were similar in pattern. From the conclusion of the stride phase, through the conclusion of the arm-cocking phase, muscle activity increased for all pitchers. In examining the relationship between the rate of axial pelvis rotation and gluteal activity, several significant relationships were observed. In contrast, no significant relationships were observed with gluteal activity parameters and the rate of axial torso rotation. However, because the pitching motion progresses sequentially from the pelvis to the torso, variability in pelvis rotation may be directly related to variability in torso rotation. The findings from this study indicate that during the baseball pitch, there is a need for greater control of gluteal activation throughout the pitching motion.

Pelvis and torso kinematics and their relationship to shoulder kinematics in high-school baseball pitchers.

Oliver, GD and Keeley, DW. Pelvis and torso kinematics and their relationship to shoulder kinematics in high-school baseball pitchers. J Strength Cond Res 24(12): 3241-3246, 2010-It was the purpose of our study to examine the kinematics of the pelvis and torso and determine their relationship to the kinematics of the shoulder in high-school baseball pitchers. A single group, repeated-measures design was used to collect pelvis, torso, and shoulder kinematics throughout the pitching motion. Subjects threw a series of maximal effort fastballs to a catcher located the regulation distance (18.44m) from the pitching mound, and those data from the fastest pitch passing through the strike zone were analyzed. After test trials, kinematic data were analyzed using a series of descriptive statistics to identify outliers and determine the nature of the distribution before testing for the presence of relationships between the various parameters. Results indicated that for several parameters, the actions at and about the shoulder are strongly related to the actions of the pelvis and torso throughout the pitching motion. However, although pelvis and torso kinematics throughout the pitching motion were inversely related to both shoulder elevation and the plane of shoulder elevation, only the rate of axial torso rotation was significantly related to these shoulder parameters. More importantly, the rate of axial torso rotation is significantly related to these shoulder parameters in a way that may help explain the high rate of shoulder injury in high-school pitchers. Therefore, strength training should focus on developing a strong stable core including the gluteal musculature in an attempt to control the rate of torso rotation during the pitch.

Functional balance training in collegiate women athletes.

Oliver, GD and Di Brezzo, R. Functional balance training in collegiate women athletes. J Strength Cond Res 23(7): 2124-2129, 2009-This study examined the effects of functional balance training implemented in addition to regular season practice, competition, and strength and conditioning training for collegiate women athletes. Twenty-six members of National Collegiate Athletic Association (NCAA) Division I collegiate womens volleyball and soccer teams volunteered. A pre-test, post-test group design was used for the study. Pre- and post-test measures were the following: Skindex, body mass index (BMI), single-leg squat, prone quadra-ped core test, Biodex balance test, and a 1-minute sit-up test. The intervention consisted of 10 minutes of Indo Board (a dynamic balance board) training 4 days a week throughout the entire season. The volleyball team served as the intervention group, whereas the soccer team had no intervention. A dependent t-test demonstrated a statistically significant (p ≤ 0.05) improvement on the single-leg squat and 1-minute sit-up test for the volleyball team, whereas the soccer team (no intervention) demonstrated a statistically significant (p ≤ 0.05) improvement on the 1-minute sit-up test. It was concluded that by training on an unstable surface, the individual is conditioning the core while simultaneously performing balance activities. It was also noted that, although improvements were seen, each participant (both volleyball and soccer) was also active in regular season practice, competition, and strength and conditioning training over the course of the season. Functional balance activities are cost effective and should be added to any form of strength and conditioning program in an attempt to enhance program effectiveness and to develop functional postural activation. Functional postural activation will not only assist with functional performance, but also in the prevention of injury.

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.

Comparison of pitching kinematics between youth and adult baseball pitchers: a meta-analytic approach

Coaches teach proper mechanics at a young age in an effort to increase pitching efficiency (i.e., proper pitching mechanics). Unfortunately, the mechanics taught to beginning pitchers are based on the findings from adult pitchers and may result in techniques that are detrimental to younger pitchers. The purpose of this study was to compare kinematics published for pitchers across various ages in an effort to determine whether the pitching techniques vary across developmental periods. A meta-analysis of papers published describing pitching kinematics for youth and adult pitchers was conducted. Maximal rotational velocity of the trunk and maximum external rotation of the shoulder were observed during the arm cocking phase. Peak magnitudes for abduction, horizontal adduction, and shoulder internal rotation were observed during the deceleration phase of the movement. In addition, by comparing previously published data across youth and adult pitchers, valuable insight into the differences in mechanics was gained. The results demonstrated that there are some distinct differences between youth and adult pitching mechanics. This finding may allow increased focus to be applied to those parameters observed to differ across age, increasing the knowledge base available for coaches to properly instruct youth pitchers.

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).

Muscle activation of different core exercises.

Oliver, GD, Dwelly, PM, Sarantis, ND, Helmer, RA, and Bonacci, JA. Muscle activation of different core exercises. J Strength Cond Res 24(11): 3069-3074, 2010-Sport health care professionals are always trying to increase muscle activation while instructing exercises that are functional to the sport performance. However, the traditional core exercises are the ones typically performed. This study examined the muscle activation of the lumbopelvic hip complex during traditional core stability exercises and that of the sports performance movements using the CORE X. Fourteen healthy, college-age men (mean age 20.8 ± 3.9 years; mean height, 177.8 ± 10.9 cm; mean weight, 67.3 ± 9.9 kg) participated. Electromyographic (EMG) data were collected on the following muscles: dominant gluteus maximus, dominant gluteus medius, rectus abdomonis (bilateral), external oblique (bilateral), and multifidis (bilateral). Results revealed a significant difference between the 2 different exercise programs for all muscles investigated except the external obliques (p < 0.05). The movements using the CORE X showed increased mean muscle activation for the dominant (57.8% maximum voluntary isometric contraction [MVIC]) and nondominant multifidus (56.4% MVIC) and the dominant gluteus maximus (48.3% MVIC) and medius (65.3% MVIC), whereas the traditional core exercises showed greater mean muscle activation for the dominant (45.1% MVIC) and nondominant rectus abdominis (47.4% MVIC) and external oblique (45.8% MVIC and 47.8% MVIC). The investigators were able to determine that while performing movements that mimicked more sports-related activities with the CORE X, there is a greater activation of the core musculature. Coaches, trainers, and athletic trainers should focus on training a core neutral while performing sports-specific movements that can be done with the CORE X.