The Effect of a High Pitch Volume on Musculoskeletal Adaptations in High School Baseball Pitchers.
Shoulder range of motion and strength adaptations occur at an early age in baseball pitchers.



The purpose of this study was to examine the effect of pitch volume on in-season and year-to-year range of motion (ROM) and strength adaptations in high school baseball pitchers. The hypothesis was that a high pitch volume will not affect range of motion asymmetries but will impair supraspinatus strength.



Cohort study; Level of evidence, 2.



Pre- and postseason ROM and strength measures were performed on pitchers from 3 high schools for 4 consecutive seasons, for a total of 95 player-seasons (mean ± SD participant age, 16 ± 1 years). Preseason measures were repeated the next year on players returning to the teams, for a total of 71 consecutive player-seasons. ROM tests included internal-external rotation and posterior shoulder flexibility. Strength tests (hand-held dynamometer) included internal-external rotation, supraspinatus, and scapular retraction. Pitchers were categorized by pitch count for the season (high, >400; moderate, 180-400; low, <180). ROM and strength changes in the dominant versus nondominant arm were assessed by analysis of variance.



Dominant versus nondominant ROM differences did not change from pre- to postseason (P = .36-.99) or from one year to the next (P = .46-.86), with no effect of pitch volume (P = .23-.87). Supraspinatus strength decreased in the dominant arm during the season, with 13% loss in high-volume pitchers (P < .001) and insignificant losses in moderate- (6%) and low-volume pitchers (2%). Strength in other tests was unaffected by pitch volume. Consistent with physical development, strength increased bilaterally from one year to the next (supraspinatus, 12%; external rotation, 15%; internal rotation, 14%; scapular retraction, 23%; P < .001). Supraspinatus strength gain in the dominant arm was affected by prior pitch volume (P = .02): 24% in low-volume pitchers (P < .01), with no significant change in moderate-volume (0%; P = .99) or high-volume (5%; P = .99) pitchers.



Dominant versus nondominant ROM differences did not progress during the season, or from one year to the next, and were unaffected by pitch volume. A high pitch volume was associated with in-season supraspinatus weakness and diminished strength gains from one year to the next. In conclusion, a high pitch volume appeared to have a catabolic effect on supraspinatus strength.
Nicholas Institute of Sports Medicine and Athletic Trauma, Lenox Hill Hospital, New York, New York, USA mchugh@nismat.org.
Malachy P
MP
McHugh
Nicholas Institute of Sports Medicine and Athletic Trauma, Lenox Hill Hospital, New York, New York, USA Pro Sports Physical Therapy, Scarsdale, New York, USA.
Timothy F
TF
Tyler
Nicholas Institute of Sports Medicine and Athletic Trauma, Lenox Hill Hospital, New York, New York, USA.
Michael J
MJ
Mullaney
Pro Sports Physical Therapy, Scarsdale, New York, USA.
Michael R
MR
Mirabella
Nicholas Institute of Sports Medicine and Athletic Trauma, Lenox Hill Hospital, New York, New York, USA.
Stephen J
SJ
Nicholas
D000222:Adaptation, Physiological; D000293:Adolescent; D001484:Baseball; D015331:Cohort Studies; D006801:Humans; D016059:Range of Motion, Articular; D012399:Rotation; D017006:Rotator Cuff / Q000502:physiology; D012540:Scapula; D012574:Schools; D012621:Seasons; D012785:Shoulder Joint / Q000502:physiology*
empty-can test; glenohumeral range of motion; hand-held dynamometer; posterior shoulder tightness; supraspinatus