A profile of glenohumeral internal and external rotation motion in the uninjured high school baseball pitcher, part II: strength.

CONTEXT

A database describing the range of normal rotator cuff strength values in uninjured high school pitchers has not been established. Chronologic factors that contribute to adaptations in strength also have not been established.

OBJECTIVES

To establish a normative profile of rotator cuff strength in uninjured high school baseball pitchers and to determine whether bilateral differences in rotator cuff strength are normal findings in this age group.

DESIGN

Cohort study.

SETTING

Baseball playing field.

PATIENTS OR OTHER PARTICIPANTS

A total of 165 uninjured male high school baseball pitchers (age = 16 ± 1 years, height=1.8±0.1 m, mass=76.8±10.1 kg, pitching experience =7±2 years).

MAIN OUTCOME MEASURE(S): Isometric rotator cuff strength was measured bilaterally with a handheld dynamometer. We calculated side-to-side differences in strength (external rotation [ER], internal rotation [IR], and the ratio of ER:IR at 90° of abduction), differences in strength by age, and the influence of chronologic factors (participant age, years of pitching experience) on limb strength.

RESULTS

Side-to-side differences in strength were found for ER, IR, and ER:IR ratio at 90° of abduction. Age at the time of testing was a significant but weak predictor of both ER strength (R(2)=0.032, P = .02) and the ER:IR ratio (R(2)=0.051 , P = .004) at 90° of abduction.

CONCLUSIONS

We established a normative profile of rotator cuff strength for the uninjured high school baseball pitcher that might be used to assist clinicians and researchers in the interpretation of muscle strength performance in this population. These data further suggested that dominant-limb adaptations in rotator cuff strength are a normal finding in this age group and did not demonstrate that these adaptations were a consequence of the age at the time of testing or the number of years of pitching experience.