Rafael f. escamilla, PT, PhD, CSCS, FACSM1 • Clare lewis, PT, PsyD, MPH, MTC, FAAOMPT2 • DunCan Bell, MPT3 Gwen BramBlet, MPT3 • Jason Daffron, MPT3 • steve lamBert, MPT3 • amanDa PeCson, MPT3 roDney imamura, PhD 4 • lonnie Paulos, MD 5 • James r. anDrews, MD 6 Core Muscle Activation During Swiss Ball and Traditional Abdominal Exercises t he "core" has been used to refer to the lumbopelvic-hip complex, which involves deeper muscles, such as the internal oblique, transversus abdominis, transversospinalis (multifidus, rotatores, semispinalis), quadratus lumborum, and psoas major and minor, and superficial muscles, such as the rectus abdominis, external oblique, erector spinae (iliocostalis, spinalis, longissimus), t ConClusions: The roll-out and pike were the most effective exercises in activating upper and lower rectus abdominis, external and internal obliques, and latissimus dorsi muscles, while minimizing lumbar paraspinals and rectus femoris activity .

We propose that learning proper hitting kinematics should be encouraged at a young age during youth baseball because this may help reinforce proper hitting kinematics as a player progresses to higher levels of baseball in their adult years. To enhance our understanding between youth and adult baseball hitting, kinematic and temporal analyses of baseball hitting were evaluated with a high-speed motion analysis system between 12 skilled youth and 12 skilled adult baseball players. There were only a small number of temporal differences between youth and adult hitters, with adult hitters taking significantly greater time than youth hitters during the stride phase and during the swing. Compared with youth hitters, adult hitters a) had significantly greater (p < .01) lead knee flexion when the hands started to move forward; b) flexed the lead knee over a greater range of motion during the transition phase (31° versus 13°); c) extended the lead knee over a greater range of motion during the bat acceleration phase (59° versus 32°); d) maintained a more open pelvis position at lead foot off ground; and e) maintained a more open upper torso position when the hands started to move forward and a more closed upper torso position at bat-ball contact. Moreover, adult hitters had greater peak upper torso angular velocity (857°/s versus 717°/s), peak left elbow extension angular velocity (752°/s versus 598°/s), peak left knee extension angular velocity (386°/s versus 303°/s), and bat linear velocity at bat-ball contact (30 m/s versus 25 m/s). The numerous differences in kinematic and temporal parameters between youth and adult hitters suggest that hitting mechanics are different between these two groups.

BACKGROUND AND PURPOSE: Performing nontraditional abdominal exercises with devices such as abdominal straps, the Power Wheel, and the Ab Revolutionizer has been suggested as a way to activate abdominal and extraneous (nonabdominal) musculature as effectively as more traditional abdominal exercises, such as the crunch and bent‐knee sit‐up. The purpose of this study was to test the effectiveness of traditional and nontraditional abdominal exercises in activating abdominal and extraneous musculature. SUBJECTS: Twenty‐one men and women who were healthy and between 23 and 43 years of age were recruited for this study. METHODS: Surface electromyography (EMG) was used to assess muscle activity from the upper and lower rectus abdominis, external and internal oblique, rectus femoris, latissimus dorsi, and lumbar paraspinal muscles while each exercise was performed. The EMG data were normalized to maximum voluntary muscle contractions. Differences in muscle activity were assessed by one‐way, repeated‐measures analysis of variance. RESULTS: Upper and lower rectus abdominis, internal oblique, and latissimus dorsi muscle EMG activity were highest for the Power Wheel (pike, knee‐up, and roll‐out), hanging knee‐up with straps, and reverse crunch inclined 30°. External oblique muscle EMG activity was highest for the Power Wheel (pike, knee‐up, and roll‐out) and hanging knee‐up with straps. Rectus femoris muscle EMG activity was highest for the Power Wheel (pike and knee‐up), reverse crunch inclined 30°, and bent‐knee sit‐up. Lumbar paraspinal muscle EMG activity was low and similar among exercises. DISCUSSION AND CONCLUSION: The Power Wheel (pike, knee‐up, and roll‐out), hanging knee‐up with straps, and reverse crunch inclined 30° not only were the most effective exercises in activating abdominal musculature but also were the most effective in activating extraneous musculature. The relatively high rectus femoris muscle activity obtained with the Power Wheel (pike and knee‐up), reverse crunch inclined 30°, and bent‐knee sit‐up may be problematic for some people with low back problems.

Except at 60 degrees and 90 degrees knee angles, patellofemoral compressive force and stress were similar between the wall squat short and the wall squat long. Between 60 degrees and 90 degrees knee angles, wall squat exercises generally produced greater patellofemoral compressive force and stress compared with the one-leg squat. When the goal is to minimize patellofemoral compressive force and stress, it may be prudent to use a smaller knee angle range between 0 degrees and 50 degrees compared with a larger knee angle range between 60 degrees and 90 degrees .

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