Male High School Baseball Players Research Articles

Match or mismatch between chronotype and sleep-wake cycle and their association with lean body mass gain among male high-school baseball players

ABSTRACT For athletes, it is important to acquire lean body mass (LBM) involving the skeletal muscle mass during their growth periods; however, the influence of chronotype on LBM gain remains unclear. We therefore aimed to investigate whether chronotype, sleep-wake cycle on weekdays (SWC-W), and their interaction contribute to LBM gain among adolescent male athletes in a 4-month intervention study. The participants were 45 male high-school baseball players. The intervention, including exercise menu (running and muscle strength training) and nutritional education, was conducted during a 4-month period of season-off training. The chronotype, body composition, lifestyle, and dietary intake were investigated before intervention (baseline) and after 4 months. Among the participants [Morningness (n = 14), Eveningness (n = 15), Intermediate (n = 16); ME score based on the Morningness/Eveningness Scale for Children (MES-C)], the midpoint of sleep on weekdays (MSW) was calculated in the “Morningness” and “Eveningness” participants, respectively. They were divided into 4 groups based on a match/mismatch with the chronotype: Type M-match (n = 8), Type M-mismatch (n = 6), Type E-match (n = 7), and Type E-mismatch (n = 8) groups. The data were compared among the 4 groups. Moreover, multiple regression analysis was conducted using an increase (kg) LBM gain as a response variable. When comparing the data between the “Morningness” and “Eveningness” participants, there were no differences in nutrient intake, the duration of training, or each parameter of body composition (per body weight) at baseline or after 4 months. There were also no differences in the rates of change in the body weight or each parameter of body composition. In groups in which the chronotype was consistent with the SWC-W (the Type M-match and Type E-match groups), the LBM gain were slightly greater than in the Type M-mismatch and Type E-mismatch groups (Type M-match: 3.5 ± 2.0 kg, Type M-mismatch: 1.6 ± 1.7 kg, Type E-match: 3.4 ± 2.2 kg, and Type E-mismatch: 1.2 ± 1.8 kg, p = .057). Multiple regression analysis revealed that an extent of the LBM gain was associated with a match between the chronotype and SWC-W (ß = 0.37, p = .030), independent of a long duration of training (ß = 0.52, p = .004). The results suggested that training-related LBM gain is associated with interactions between the chronotype and SWC-W in adolescent male athletes. Abbreviations: LBM: Lean body mass; SWC-W: Sleep-wake cycle on weekdays; ME score: Morningness-eveningness score; MES-C: Morningness/Eveningness Scale for Children; MSW: Midpoint of sleep on weekdays; MSF: Midpoint of sleep on free days; MSFsc: Midpoint of sleep on free days corrected for sleep debt accumulated through weekdays

The Intra- and Inter-rater Reliability of an Arm Care Screening Tool in High School Baseball Coaches.

BackgroundPreseason movement screening can identify modifiable risk factors, deterioration of function, and potential for injury in baseball players. Limited resources and time intensive testing procedures prevent high school coaches from accurately performing frequent movement screens on their players.PurposeTo establish the intra-rater and inter-rater reliability of a novel arm care screening tool based on the concepts of the Functional Movement Screen (FMS™) and Selective Functional Movement Assessment (SFMA™) in high school coaches.Study DesignMethodological intra- and inter-rater reliability studyMethodsThirty-one male high school baseball players (15.9 years ± 1.06) were independently scored on the Arm Care Screen (ACS) by three examiners (two coaches, one physical therapist) in real-time and again seven days later by reviewing video recordings of each players’ initial screening performance. Results from each examiner were compared within and between raters using Cohen’s kappa and percent absolute agreement.ResultsSubstantial to excellent intra-rater and inter-rater reliability were established among all raters for each component of the ACS. The mean Cohen’s kappa coefficient for intra-rater reliability was 0.76 (95% confidence interval, 0.54-0.95) and percent absolute agreement ranged from 0.82-0.94 among all raters. Inter-rater reliability demonstrated a mean Cohen’s kappa value of 0.89 (95% confidence interval, 0.77-0.99) while percent absolute agreement between raters ranged from 0.81-1.00. Intra- and inter-rater reliability did not differ between raters with various movement screening experience (p>0.05).ConclusionsHigh school baseball coaches with limited experience screening movement can reliably score all three components of the ACS in less than three minutes with minimal training.Level of EvidenceLevel 3, Reliability study

Acute effects of doorway stretch on the glenohumeral rotational range of motion and scapular position in high-school baseball players.

BackgroundPectoralis minor tightness has been thought to affect the scapular position. Despite the wide implementation of doorway stretch in clinical practice owing to its apparent effectiveness in stretching the pectoralis minor, limited studies have investigated its influence on the glenohumeral rotational range of motion (ROM). This study aimed to examine the acute effects of doorway stretch on the glenohumeral rotational ROM and the correlation between the scapular position and ROM.Materials and MethodsIn total, 34 male high-school baseball players participated in this study. Outcomes included the pectoralis minor muscle length, glenohumeral rotational ROM, and scapular position. The distance between the sternocostal joint of rib 4 and the coracoid process was measured as the pectoralis minor length. Internal and external rotation ROM with the shoulder abducted at 90° were measured. The scapular position was defined by the following two measurements: the distance between the surface and the posterolateral corner of the acromion as well as the scapular index. The participants performed doorway stretch by abducting and externally rotating the shoulder at 90° and flexing the elbow at 90°. The outcomes were compared before and after stretching. Furthermore, the correlation between these changes was investigated.ResultsPectoralis minor muscle length and glenohumeral internal rotation ROM was significantly higher after stretching than before, and the scapular position also significantly changed (P < .01 for both). A moderate correlation was found between the degree of change in the glenohumeral internal rotational ROM and scapular position (r = 0.44, P < .01).DiscussionOur results indicated that doorway stretch significantly increased the pectoralis minor muscle length and glenohumeral internal rotation ROM and significantly altered the scapular position. Furthermore, a significant correlation between the degree of change in the scapular position and glenohumeral internal rotation ROM was observed. These results suggest that doorway stretch could be beneficial for improving the scapular position and glenohumeral internal rotation ROM, which are considered the cause of throwing injuries. Furthermore, the glenohumeral ROM may be affected by the scapular position.

Relationship between humeral retroversion and baseball positions during elementary and junior-high school

Humeral retroversion is greater in the dominant shoulder than in the nondominant shoulder in baseball players. However, the effect of different baseball positions during childhood on humeral retroversion remains unknown. The purpose of this study was to investigate the following: (1) the relationship between humeral retroversion and baseball positions played during elementary and junior-high schools; (2) the association between humeral retroversion and the prevalence of pain during the medical checkup and self-reported history of injuries in the dominant shoulder or elbow. We enrolled 149 male high-school baseball players who started playing baseball in elementary school. The subjects were classified into 3 groups according to their baseball positions in elementary and junior-high schools. All participants completed questionnaires regarding their current and past positions, current incidence and history of injuries in their shoulder or elbow joints, and the age they started playing baseball. Shoulder range of motion, humeral retroversion on ultrasonographic-assisted measurement, and the association between humeral retroversion and shoulder and elbow pain were evaluated. Humeral retroversion was significantly greater in the dominant shoulder than in the nondominant shoulder in all groups (P < .001). In addition, humeral retroversion in the dominant shoulder was significantly greater in players who were pitchers in both elementary and junior-high schools than in those who were fielders during both periods (96.2° and 89.4°, respectively; P = .02). Humeral retroversion in the dominant shoulder was positively correlated (P = .005, r = 0.23) with the length of career as a pitcher during elementary and junior-high schools. Humeral retroversion was not correlated with the prevalence of pain during the medical checkup or self-reported history of injuries in the dominant shoulder or elbow (P values ranging from 0.09-0.99). These results suggest that playing baseball as a pitcher during elementary school and junior-high school affects the increase in humeral retroversion in the dominant shoulder. Increased humeral retroversion in the dominant shoulder by repetitive throwing motion is an adaptive change, rather than a pathologic change.

Functional movement screen comparison between the preparative period and competitive period in high school baseball players

Background/ObjectiveAlthough the functional movement screen (FMS) has been widely applied for screening athletes, no previous study has used FMS scores to examine the association between distinct training seasons in high school baseball players. The aims of this study were to ascertain the functional movement screen (FMS) scores differences between the preparative period (PPP) and the competitive period (CPP) among high school baseball players and further determine whether FMS can be used as a tool to predict injuries during two major periods. MethodsFifty-five male high school baseball players (age 15.3 ± 1.7 years; height 1.7 ± 0.8 m; weight 64.6 ± 11.5 kg) volunteered. Athletic injuries were reported through a self-report questionnaire. Players performed the FMS during the PPP and the CPP. A receiver operator characteristic (ROC) curve to calculate a cutoff total composite score ≤ 14 for the relationship between the FMS score and injury. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and an area under the curve (AUC) were calculated. ResultsFMS individual task score and total composite score were significantly lower in the CPP than in the PPP. However, a cutoff total composite score ≤14 for risk of injury, determined through a ROC curve, represented a low sensitivity of 58%, NPV of 66%, an AUC of 69%, specificity of 79%, and PPV of 71%. ConclusionAlthough the low sensitivity and NPV and AUC scores indicated that the FMS does not accurately predict the risk of injury, the FMS individual task and total composite scores differed significantly between the PPP and CPP. Therefore, FMS could be used as a tool to identify physical deficiencies between distinct training seasons; however, utilizing the FMS as a screening tool for injury prediction in particular during the CPP in this population would not be recommended.

The effect of glenohumeral internal rotation deficit on the isokinetic strength, pain, and quality of life in male high school baseball players.

ObjectiveTo investigate the effects of glenohumeral internal rotation deficit (GIRD) on the isokinetic strength, body pain, and the quality of life in male high school baseball players of Korea.MethodsFifty-six male high school baseball players were divided into either group A (GIRD≥20°, n=12) or group B (GIRD<20°, n=44). The range of motion in the shoulder and the isokinetic strength were measured. Questionnaires were administered regarding the body pain location by using the visual analogue scale, and the quality of life was measured by using the SF-36 Form.ResultsAll subjects had increased external rotation range of motion and decreased internal rotation in the throwing shoulder. The incidence of GIRD (≥20°) was 21.43% in the present study. In the isokinetic strength test, a significantly weaker muscular state at an angular velocity of 180°/s was observed in group A, compared to group B. For the comparison of the pain, the frequency of shoulder pain was higher (33.93%) than other body pain, among the study subjects.ConclusionGIRD is one of the main risk factors of glenohumeral joint damage, and it is correlated with reduced isokinetic strength and quality of life. High school baseball players will need appropriate shoulder rehabilitation programs for the improvement in their quality of life and performance.

Effects of 16-week functional movement screen training program on strength and flexibility of elite high school baseball players.

Functional Movement Screen (FMS) is a way to pretest functional movement. This study examined the effects of the FMS training program on the strength and flexibility of 62 elite male high school baseball players (31 in the training group, 31 in the control group). All players who received less than two points on each FMS test item had to join the 16-week, three times weekly FMS training program. To analyze results among the FMS participants, measures including intraclass correlation coefficient (ICC) and repeated measure ANOVA were utilized. The Kappa coefficient was 0.805 when the intraclass correlation coefficient of the three participants was inspected. Strength showed a significant interaction depending on time and group (hand grip strength: P=0.011, bench press and squat both for one-repetition maximum (1RM): P=0.001 and P=0.008, respectively). Back muscle strength did not show a significant difference (P=0.660). Trunk forward flexion showed no interaction depending on time and groups (P=0.983) but trunk extension backward showed significant differences depending on groups (P=0.004) and time (P=0.001). Splits showed a significant difference depending on time and groups (P=0.004). The FMS training program improved the strength and flexibility of elite high school baseball players.

The Effect of Glenohumeral Internal Rotation Deficit Improving Rehabilitation Program in the Male High-School Baseball Players

To investigate the effect of the glenohumeral internal rotation deficit (GIRD) improving rehabilitation program in high school baseball players on the change in muscle strength balance and pain of their shoulders. Seventy-six players (35 control group, 41 experimental group) participated in this 6-month study, from April, 2012 to September, 2012. The rehabilitation program (sleeper stretch) was carried out by coaches of experimental group. The experimental group showed a significant decrease, while the control group didn't show significant change in GIRD. The shoulder flexion-extension isokinetic strength ratio of experimental group changed only slightly, while that of control group experienced a bigger change. Experimental group players initially had high frequency of shoulder pain, but decreased to 53% at the end. Also, the Short Form-36 Health Survey showed the increase of total score. GIRD improving rehabilitation program helps to maintain the balance of shoulder extension-flexion strength ratio and relieve shoulder pain in the baseball players.

Relationship Between Upper-Body Strength and Bat Swing Speed in High-School Baseball Players

This study aimed to clarify the relationship between upper-body strength and bat swing speed in high-school baseball players and to examine the physical characteristics of home run hitters (sluggers). The subjects were 30 male high-school baseball players with national tournament experience at the Koshien Stadium. Bat swing speed exerted by full effort was measured with a microwave-type speed-measuring instrument. One-repetition maximum (1RM) of a bench press (BP), BP power (bench power) using a light load (30 kg), and isokinetic chest press (0.4, 0.8, 1.2 m·s(-1)) were measured as upper-body strength. The relationships between bat swing speed and upper-body strength values were examined. Additionally, the t-test was used to reveal the mean differences between 14 home run hitters (group A) and 16 mediocre hitters (group B) for each measurement value. The bat swing speed showed significant and middle correlations with the 1RM BP (r = 0.59), bench power (0.41), and isokinetic chest press (0.48-0.55). Group A had significantly higher values in bench power and isokinetic chest press (high-speed) per kilogram of body weight than did group B. The swing speed showed significant correlations (r = 0.62) with the 1RM BP in group B but not in group A. In conclusion, to improve the hitting power of high-school baseball players, it may also be important to develop bench power with light loads in addition to 1RM BP.

投球動作の肩最大外旋角度に相関する要因

The magnitude of mechanical stress at the shoulder and elbow appears to be directly correlated with the degree of maximum shoulder external rotation (MER) during throwing. Therefore, it is very important to prevent excessive MER to minimize the risk of throwing injuries. The purpose of this study was to investigate the relationships between MER during throwing and the kinematic parameters of throwing mechanics, shoulder muscle strength, and shoulder range of motion in high school baseball players. The subjects were 40 male high school baseball players with no elbow or shoulder joint problems. Three-dimensional analysis was performed to calculate the MER angle. Then, the shoulder and elbow angles at initial foot contact (IFC) were computed. ROM and muscle strength of shoulder joint were also measured in each subject. Multiple linear regression analysis was used to relate the MER angle to these factors. Significant correlations were observed between the MER angle and the external rotation (ER) angle (r=−0.51, p<0.001) at IFC, and the ER range of motion (r=0.84, p<0.01). The MER angle significantly correlated with shoulder internal rotation (IR) at IFC. This finding suggests that stress on the shoulder and elbow could be increased by the degree of shoulder IR angle at the moment of IFC. Further, excessive ER range of motion may also be a risk factor.

Changes in the concentrations of urinary proteins after physical exercise.

The influence of physical exercise on the urinary excretion of proteins was examined in 17 male high school baseball players. Their urine was collected before and after exercise to determine the concentrations of total protein, albumin, beta 2-microglobulin and creatinine along with the activity of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30). Concentrations of total protein, albumin, beta 2-microglobulin and creatinine increased significantly (p less than 0.01) after exercise, while N-acetyl-beta-D-glucosaminidase activity did not increase. Similar results were obtained when the concentrations of these urinary components were calculated on the basis of a urinary density of 1.024, and when they were expressed relative to the amount of creatinine. Positive correlations were seen among total protein, albumin, beta 2-microglobulin and creatinine concentrations, but not between the beta 2-microglobulin concentration and N-acetyl-beta-D-glucosaminidase activity. Isoenzyme activities of N-acetyl-beta-D-glucosaminidase in the urine were determined by electrophoresis on cellulose acetate plates. After exercise, the A-form increased slightly, and the B-form decreased slightly, but these changes were not statistically significant.