Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players
# BACKGROUND Despite increased awareness of factors related to athletic performance and injury prevention, youth and adolescent baseball players continue to report injuries at alarming rates. Upper extremity muscle strength is an integral part of physical assessment and injury prevention in basebal...
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| Format: | Article |
| Language: | English |
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North American Sports Medicine Institute
2022-02-01
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| Series: | International Journal of Sports Physical Therapy |
| Online Access: | https://doi.org/10.26603/001c.31045 |
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| _version_ | 1825197119654330368 |
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| author | Amanda J Arnold Charles A Thigpen Paul F Beattie Stacy L Fritz Michael J Kissenberth John M Tokish Ellen Shanley |
| author_facet | Amanda J Arnold Charles A Thigpen Paul F Beattie Stacy L Fritz Michael J Kissenberth John M Tokish Ellen Shanley |
| author_sort | Amanda J Arnold |
| collection | DOAJ |
| description | # BACKGROUND
Despite increased awareness of factors related to athletic performance and injury prevention, youth and adolescent baseball players continue to report injuries at alarming rates. Upper extremity muscle strength is an integral part of physical assessment and injury prevention in baseball players, however minimal data exists in youth populations. Changes in anthropometric measures, inherent in physically developing athletes, have been shown to impact strength measures, however normalization methodology is rarely reported.
# PURPOSE
The purposes of this study were to 1) compare the measurement properties of five potential methods for normalizing isometric shoulder strength in a cohort of 9-12 year old male baseball players and 2) examine the relationship between normalized isometric shoulder strength and ball velocity in a cohort of 9-12 year old male baseball players.
# STUDY DESIGN
Prospective cohort study (n=159)
# METHODS
Baseline and follow up height, weight and bilateral ulnar length measurements were assessed followed by isometric strength in both the dominant and non-dominant shoulders. Strength measures included scapular plane abduction (scaption), external rotation (ER) at 0°, ER and internal rotation (IR) at 90°. Ball velocity was assessed as a measure of throwing performance. Intraclass correlation coefficients (ICC2,1), standard errors of measurement (SEM) and minimal detectable change (MDC95) were calculated for all strength measures. Repeated measures ANOVA were conducted comparing changes in normalized strength using five separate anthropometric measures: weight, height, body mass index, ulnar length and % of non-dominant shoulder strength. Linear regression models were used to examine the relationships between normalized isometric shoulder strength and ball velocity. Statistical significance was set a priori at α=0.05.
# RESULTS
Shoulder strength normalized using ulnar length was the only method that demonstrated excellent reliability (ICC2,1 0.98-0.99) and detected significant changes between strength in each of the four measures tested (SEM 0.39-0.69 Nm). Modest but significant correlations were observed between scaption and ball velocity (r2 = 0.27, p < 0.001) and ER at 0° and ball velocity (r2 = 0.23, p < 0.001).
# CONCLUSION
Ulnar length was the most stable and reliable normalization method for assessing isometric shoulder strength in youth baseball players. In addition, normalized scaption strength was the most significant predictor of ball velocity, followed by ER at 0° strength in this population.
# LEVEL OF EVIDENCE
Level 2b (etiology) |
| format | Article |
| id | doaj-art-c10d447ddbbd475382c4f754825a81e8 |
| institution | Kabale University |
| issn | 2159-2896 |
| language | English |
| publishDate | 2022-02-01 |
| publisher | North American Sports Medicine Institute |
| record_format | Article |
| series | International Journal of Sports Physical Therapy |
| spelling | doaj-art-c10d447ddbbd475382c4f754825a81e82025-02-11T20:27:05ZengNorth American Sports Medicine InstituteInternational Journal of Sports Physical Therapy2159-28962022-02-01172Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball PlayersAmanda J ArnoldCharles A ThigpenPaul F BeattieStacy L FritzMichael J KissenberthJohn M TokishEllen Shanley# BACKGROUND Despite increased awareness of factors related to athletic performance and injury prevention, youth and adolescent baseball players continue to report injuries at alarming rates. Upper extremity muscle strength is an integral part of physical assessment and injury prevention in baseball players, however minimal data exists in youth populations. Changes in anthropometric measures, inherent in physically developing athletes, have been shown to impact strength measures, however normalization methodology is rarely reported. # PURPOSE The purposes of this study were to 1) compare the measurement properties of five potential methods for normalizing isometric shoulder strength in a cohort of 9-12 year old male baseball players and 2) examine the relationship between normalized isometric shoulder strength and ball velocity in a cohort of 9-12 year old male baseball players. # STUDY DESIGN Prospective cohort study (n=159) # METHODS Baseline and follow up height, weight and bilateral ulnar length measurements were assessed followed by isometric strength in both the dominant and non-dominant shoulders. Strength measures included scapular plane abduction (scaption), external rotation (ER) at 0°, ER and internal rotation (IR) at 90°. Ball velocity was assessed as a measure of throwing performance. Intraclass correlation coefficients (ICC2,1), standard errors of measurement (SEM) and minimal detectable change (MDC95) were calculated for all strength measures. Repeated measures ANOVA were conducted comparing changes in normalized strength using five separate anthropometric measures: weight, height, body mass index, ulnar length and % of non-dominant shoulder strength. Linear regression models were used to examine the relationships between normalized isometric shoulder strength and ball velocity. Statistical significance was set a priori at α=0.05. # RESULTS Shoulder strength normalized using ulnar length was the only method that demonstrated excellent reliability (ICC2,1 0.98-0.99) and detected significant changes between strength in each of the four measures tested (SEM 0.39-0.69 Nm). Modest but significant correlations were observed between scaption and ball velocity (r2 = 0.27, p < 0.001) and ER at 0° and ball velocity (r2 = 0.23, p < 0.001). # CONCLUSION Ulnar length was the most stable and reliable normalization method for assessing isometric shoulder strength in youth baseball players. In addition, normalized scaption strength was the most significant predictor of ball velocity, followed by ER at 0° strength in this population. # LEVEL OF EVIDENCE Level 2b (etiology)https://doi.org/10.26603/001c.31045 |
| spellingShingle | Amanda J Arnold Charles A Thigpen Paul F Beattie Stacy L Fritz Michael J Kissenberth John M Tokish Ellen Shanley Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players International Journal of Sports Physical Therapy |
| title | Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players |
| title_full | Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players |
| title_fullStr | Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players |
| title_full_unstemmed | Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players |
| title_short | Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players |
| title_sort | normalized isometric shoulder strength as a predictor of ball velocity in youth baseball players |
| url | https://doi.org/10.26603/001c.31045 |
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