Our results demonstrate that the existence of a relationship between training load and injury continues to be well supported in the literature and is strongest for subjective internal training load. The directionality of this relationship appears to depend on the type and timeframe of load measured.

Muscle activation of the upper extremity limits the medial elbow joint space, suggesting that injury prevention programs for throwing athletes should incorporate exercises for the elbow, wrist, and hand to limit excessive medial elbow joint space gapping during activities that create high valgus load.

Objectives To evaluate changes in the femoral cartilage cross‐sectional area (CSA) measured with ultrasound (US) between baseline and 1000, 2000, 3000, 4000, and 5000 steps of walking on a treadmill. Methods Forty‐one healthy individuals completed a single testing session. Participants rested with their knees extended on a plinth for 45 minutes to unload the femoral cartilage. Ultrasound was used to acquire images of the femoral cartilage before the treadmill‐walking protocol. After the baseline US acquisition, participants walked on a treadmill at their preferred overground walking speed for 1000 steps, after which additional US images of the femoral cartilage were acquired. This process was repeated after 2000, 3000, 4000, and 5000 steps. A 1‐way repeated‐measures analysis of variance compared the CSA across the 6 step counts. An analysis of variance with repeated measures on time and Bonferroni corrected planned comparisons (.05/5) were used to evaluate differences in the femoral cartilage at each step count compared to baseline. Results The study included 20 male and 21 female participants (mean age ± SD, 21.5 ± 2.8 years; mean body mass index, 24.3 ± 3.4 kg/m 2 ). The CSAs were significantly greater at the 2000‐step (1.27 ± 1.75 mm 2 ; P < .001), 4000‐step (0.89 ± 1.17 mm2; P < .001), and 5000‐step (2.10 ± 1.73 mm 2 ; P < .001) points compared to baseline. The CSA was significantly less at the 3000‐step point (1.05 ± 1.29 mm 2 ; P < .001) compared to baseline. Conclusions Changes in the CSA after walking may be dependent on the number of steps. The participants had a significant decrease in the CSA after 3000 steps of normal walking and a significant increase in the CSA after 2000, 4000, and 5000 steps of normal walking.

The results of the study demonstrate infraspinatus CSA does not recover until 2 days following pitching, and IRROM does not recover until 4 days following pitching. Baseball pitching elicits damage to the posterior shoulder muscle architecture, resulting in changes to physical characteristics that last up to 4 days following pitching.

Context A baseball-specific training load may influence strength or glenohumeral range of motion, which are related to baseball injuries. Glenohumeral reach tests and grip strength are clinical assessments of shoulder range of motion and upper extremity strength, respectively. Objective To examine changes in glenohumeral reach test performance and grip strength between dominant and nondominant limbs and high, moderate, and low baseball-specific training load groups. Design Repeated-measures study. Setting University laboratory and satellite clinic. Patients or Other Participants Collegiate baseball athletes (n = 18, age = 20.1 ± 1.3 years, height = 185.0 ± 6.5 cm, mass = 90.9 ± 10.2 kg). Main Outcome Measure(s) Participants performed overhead reach tests (OHRTs), behind-the-back reach tests (BBRTs), and grip strength assessments using the dominant and nondominant limbs every 4 weeks for 16 weeks. Percentage change scores were calculated between testing times. After each training session, participants provided their duration of baseball activity, throw count, and body-specific and arm-specific ratings of perceived exertion. We classified them in the high, moderate, or low training load group based on each training load variable: body specific acute:chronic workload ratio (ACWR), arm-specific ACWR, body-specific cumulative load, and arm-specific cumulative load. Mixed models were used to compare training load groups and limbs. Results The arm-specific ACWR group demonstrated a main effect for OHRT (F = 7.70, P = .001), BBRT (F = 4.01, P = .029), and grip strength (F = 8.89, P &lt; .001). For the OHRT, the moderate training load group demonstrated a 10.8% greater increase than the high group (P = .004) and a 13.2% greater increase than the low group (P &lt; .001). For the BBRT, the low training load group had a 10.1% greater increase than the moderate group (P = .011). For grip strength, the low training load group demonstrated a 12.1% greater increase than the high group (P = .006) and a 17.7% greater increase than the moderate group (P &lt; .001). Conclusions Arm-specific ACWR was related to changes in clinical assessments of range of motion and strength. Clinicians may use arm-specific ACWR to indicate when a baseball athlete's physical health is changing.