Throw down the gauntlet.
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As the most mobile joint in the body, the shoulder is structurally insecure. The ball-shaped humeral head rotates and glides on a shallow scapular cup. A limited amount of passive stability is provided by the glenoid labrum, which slightly deepens the scapular cup, and by ligaments reinforcing the capsule on its superior and anterior surfaces. At peak maturity ligamentous restraint equals 50 to 80 kg. These structural limitations indicate that the primary source of joint stability must be balanced muscle control. Joint compression is the major factor. This is supplemented by active tangential restraint, which selectively opposes anterior, posterior, or superior displacement. The large external muscles used for purposeful motion and speed often create subluxating shear forces in addition to the desired actions. Impingement and attrition syndromes are common consequences. To counter this, as well as to provide selective rotation, there are the four muscles that constitute the rotator cuff. Joint compression is the major force generated by the supraspinatus and infraspinatus. The latter (accompanied by the teres minor) also provides a downward pull to oppose the upward displacement of early deltoid action. Anterior protection against excessive external rotation or extension is offered by the subscapularis. Athletic who use the arm for a propelling force strain the extremes of joint range in their drive for maximum performance. The threat of injury can be minimized by two actions, namely, modifying motion patterns, which may avoid impingement or make it a less frequent experience, and active protection, which is gained through specific strengthening of the rotator cuff muscles.
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BACKGROUND: Altered mobility patterns in the throwing shoulders of professional baseball pitchers have been reported. Most published reports examining glenohumeral laxity have not used an objective testing device. OBJECTIVE: Quantify and compare glenohumeral translation and rotational range of motion between the throwing and non-throwing shoulders in professional baseball pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: Force-displacement and range of motion measures were performed bilaterally on 43 asymptomatic professional baseball pitchers. Ultrasound imaging was used to measure glenohumeral translations under stressed and unstressed conditions. RESULTS: No significant difference in translation was found between the throwing and nonthrowing shoulders. For both shoulders, posterior translation (5.38 +/- 2.7 mm) was significantly greater (P < .001) than was anterior translation (2.81 +/- 1.6 mm). External rotation in the throwing shoulder was significantly greater than that in the nonthrowing shoulder (P < .001), whereas internal rotation in the throwing shoulder was significantly less than that in the nonthrowing shoulder (P < .001). The total arc of rotation for the throwing shoulder was not significantly different than that for the nonthrowing shoulder, and correlation coefficients were poor between rotational and translational range of motion in the throwing shoulder, ranging from r = 0.232 to 0.209 between variables. CONCLUSION: No significant difference in glenohumeral translation exists between the throwing and nonthrowing shoulders in asymptomatic professional baseball pitchers, posterior translation is significantly greater than anterior translation in the throwing shoulders of professional baseball pitchers, and glenohumeral translation is not related to rotational range of motion in the throwing shoulders of professional baseball pitchers. CLINICAL RELEVANCE: Altered mobility patterns in asymptomatic professional baseball pitchers may be due to factors other than capsular adaptive changes.
While both discus and hammer throwing involve rotating movements resulting in the throw of an object, discus throwers sometimes report dizziness, a condition never experienced by hammer throwers. We investigated whether this susceptibility was related to the sensitivity of the thrower or to the type of throwing achieved. For the latter, we compared the determining features of gesture, gaze stabilization and projectile trajectory in both sports. A total of 22 high-level sportsmen in these 2 disciplines, half of them practising both sports, were interviewed. Slow motion video recordings of discus and hammer throwing were examined to determine the visual referential, head movements and plantar surface support area involved at each stage of the motions. Discomfort was reported by 59% of the sportsmen while throwing discus, but by none while throwing hammer. Because several individuals practised both sports, these results exclude the hypothesis of individual susceptibility to dizziness. Video analysis evidenced that during hammer throwing, visual bearings can be used more easily than during discus throwing. Moreover, there is a loss of plantar afferents and generation of head movements liable to induce motion sickness, such as Coriolis acceleration. In conclusion, although hammer and discus-throwing present numerous similarities, we demonstrate here that crucial differences in the specific execution of each sport are responsible for the dizziness experienced by discus throwers.
The purpose of this scientific investigation was to identify the determinants of suture extrusion following subcuticular skin closure of dermal skin wounds. Miniature swine were used to develop a model for studying suture extrusion. Standard, full-thickness skin incisions were made on each leg and the abdomen. The wounds were closed with size 4/0 POLYSORB* or COATED VICRYL* sutures. Each incision was closed with five interrupted, subcuticular, vertical loops secured with a surgeon's knot. The loops were secured with 3-throw knots in one pig, 4-throw knots in the second pig, and 5-throw knots in the third pig. The swine model reproduced the human clinical experience and suture extrusion, wound dehiscence, stitch abscess, and granuloma formation were all observed. The cumulative incidence of suture extrusion over 5 weeks ranged from 10 to 33%. COATED VICRYL* sutures had a higher mean cumulative incidence of suture extrusion than that of POLYSORB* sutures (31% vs. 19%). With POLYSORB* sutures, the 5-throw surgeon's knots had a higher cumulative incidence of suture extrusion than the 3-throw or 4-throw surgeon's knot square, 30% vs. 17% and 10%, respectively. This swine model offers an opportunity to study the parameters that influence suture extrusion. Because the volume of suture material in the wound is obviously a critical determinant of suture extrusion, it is imperative that the surgeon construct a knot that fails by breakage, rather than by slippage with the least number of throws. Because both braided absorbable suture materials are constructed with a secure surgical knot that fails only by breakage rather than slippage with a 3-throw surgeon's knot square (2 = 1 = 1), the construction of additional throws with these sutures does not enhance the suture holding capacity but plays a key factor in precipitating suture extrusion. Finally, it is important to emphasize that the surgeon must always construct symmetrical surgical knots for dermal subcuticular skin closure in which the constructed knot is always positioned perpendicular to the linear wound incision. Asymmetrical knot construction for dermal wound closure becomes an obvious invitation for suture extrusion.
The study investigated the effects of the direct and exploration methods of teaching on the overhand throwing performance of kindergarten children. Variable throwing practice was provided in the exploration method by allowing children to throw 5 different types of balls at a variety of targets. Children given the direct method threw only one type of ball and received specific instruction and demonstrations. Throwing for distance and throwing accuracy were measured on pre- and posttests. A novel throwing task was administered on the posttest to measure skill transfer. The experimental groups received instruction three times per week for 4 wk. in throwing while a control group received no instruction. Significant sex differences in throws were found for distance and accuracy. Analysis of data from the novel task gave no significant effects. The two methods of teaching did not produce different levels of throwing skill.
BACKGROUND: The incidence of ulnar collateral ligament injury has increased in baseball, especially at the high school level. HYPOTHESIS: Ulnar collateral ligament injury in high school baseball players is associated with overuse, high-velocity throwing, early throwing of breaking pitches, and improper warm-ups. STUDY DESIGN: Retrospective cohort study. METHODS: Follow-up physical examination and questionnaire data were collected at an average of 35 months after ulnar collateral ligament reconstruction from 27 former high school baseball players. Six potential risk factors were evaluated: year-round throwing, seasonal overuse, event overuse, throwing velocity more than 80 mph, throwing breaking pitches before age 14, and inadequate warm-ups. RESULTS: Overall, 74% returned to baseball at the same or higher level. Patients averaged 3 potential risk factors, and 85% demonstrated at least one overuse category. Of the pitchers, the average self-reported fastball velocity was 83 mph, and 67% threw breaking pitches before age 14. CONCLUSIONS: The success rate of ulnar collateral ligament reconstruction in high school baseball players is nearly equal to that in more mature groups of throwers. Overuse of the throwing arm and throwing breaking pitches at an early age may be related to their injuries. Special attention should be paid to elite-level teenage pitchers who throw with high velocity.
Although explosive power in lower-body movements has been extensively studied, there is a paucity of research examining such movements in the upper body. This study aimed to investigate the influence of load and the stretch shortening cycle (SSC) on the kinematics, kinetics, and muscle activation that occurs during maximal effort throws. A total of 17 male subjects performed SSC and concentric only (CO) bench throws using loads of 15%, 30%, 45%, 60%, 75%, 90% and 100% of their previously determined one repetition maximum bench press. The displacement, velocity, acceleration, force and power output as well as the electromyogram (EMG) from pectoralis major, anterior deltoid, and triceps brachii were recorded for each throw. The results were compared using multivariate analysis of variance with repeated measures. A criterion alpha level of P < or = 0.05 was used. Similar force velocity power relationships were determined for this multijoint upper-body movement as has been found for isolated muscles, single joint movements, and vertical jumping. The highest power output was produced at the 30% [563 (104) W] and 45% [560 (86) W] loads during the SSC throws. Force output increased as a function of load; however, even the lighter loads resulted in considerable force due to the high accelerations produced. Average velocity, average and peak force, and average and peak power output were significantly higher for the SSC throws compared to the CO throws. However, peak velocity and height thrown were not potentiated by performing the pre-stretch because the duration and range of movement allowed the ability of the muscle to generate force at high shortening velocities to dominate the resulting throw. As such, explosive movements involving longer concentric actions than experienced during brief SSC movements may be limited by the ability of the muscle to produce force during fast contraction velocities.
OBJECTIVE: The study was performed to test the knot integrity of parallel and nonidentical sliding knots with the use of monofilament suture. STUDY DESIGN: We investigated the proportion of parallel sliding knots that become untied compared with nonidentical sliding knots in four different monofilament suture configurations: group A, 6 throws, 0-0 gauge; group B, 10 throws, 0-0 gauge; group C, 6 throws, 2-0 gauge; group D, 10 throws, 2-0 gauge. Each combination was tested 20 times, for a total of 160 knots. RESULTS: The nonidentical sliding knot untied 40% of the time in group A compared with 0% for the parallel knot (P=.003). In the other 6-throw group, group C, 45% of the nonidentical knots became untied compared with 0% of the parallel knots (P=.001). There were no significant differences in the proportions of untying for each knot type in the 10-throw groups. CONCLUSION: Parallel sliding knots demonstrate superior knot integrity compared with nonidentical sliding knots with monofilament suture. The addition of throws to the nonidentical knot improves its knot security.
The purpose of this study was to evaluate the validity and reliability of a medicine ball throw test to assess explosive power. Twenty competitive sand volleyball players (10 male players, 10 female players) performed a medicine ball throw and a standard countermovement vertical jump. The subjects attended 2 sessions; at each session, 3 attempts of each test were completed. The movement pattern for the medicine ball throw was a backward overhead toss. To standardize for body weight, a power index was calculated for the countermovement vertical jump using the Lewis formula. Validity was assessed using the best score for both the throw and the jump, and reliability was assessed using the best score from each session. There was a strong correlation between the distance of the medicine ball throw and the power index for the countermovement vertical jump (r = 0.906, p < 0.01). For the countermovement vertical jump, the test-retest reliability was 0.993 (p < 0.01), and for the medicine ball throw, the test-retest reliability was 0.996 (p < 0.01). These findings suggest that the medicine ball throw test is a valid and reliable test for assessing explosive power for an analogous total-body movement pattern and general athletic ability.