Livingston JL, Tavoukjian NM. Lower extremity strength and recovery time in youth baseball pitchers: A pilot study. J Strength Cond Res. 2018; Pub Online:1-32. doi:10.1519/JSC.0000000000002454.
Throwing with arm fatigue has been associated with decreased velocity, accuracy, arm soreness, and increased risk for injury in youth baseball players. Little League pitch count and rest day recommendations are designed to minimize the deleterious effects of throwing with fatigue. Arm strength has been shown to remain reduced for several days following a bout of pitching in teenage athletes1. A great deal of attention has been devoted to improving arm strength and endurance in overhead athletes. However, the lower body musculature is responsible for generating a large portion of the forces during pitching. Strength and the ability of lower body muscles to recover between pitching bouts may be a key factor in sustaining performance and reducing the risk for injury in youth baseball players.
The purpose of this study was to investigate changes in lower extremity force production immediately after pitching and over the subsequent days of rest in Little League baseball players.
- Male Little League pitchers age 8-11 years (n=15)
- No history of injury during the prior 2 months
The following lower body muscles were tested with a handheld dynamometer for force generating capacity: gluteus maximus, gluteus medius, piriformis, quadriceps, gastrocnemius, and hamstring. Following a dynamic warm-up, research participants performed a submaximal pitching session. Pitch count was determined based on pitching experience with consideration for Little League pitch count and rest day requirements. Immediately following throwing, participants were again tested with the handheld dynamometer. The same muscle testing procedures were followed for the next 4 days to determine each individual muscle’s ability to return to its baseline strength level.
- No player was fully recovered based on the timeline recommended by Little League baseball
- There was a significant difference (P=0.017) between the rest time required for all muscles groups to recover and the rest time prescribed by Little League baseball.
- The difference between mandated and actual rest time was significantly lower (p=0.049) for those who played multiple sports vs. those who specialized in baseball.
- When comparing pre-test to immediately post-pitching, the following muscle groups showed significantly reduced strength: gastrocnemius, quadriceps, gluteus medius, and hamstrings.
- For all muscle groups, older players demonstrated a lower percentage of baseline strength during post-testing.
- Research participants were 11 years old and younger
- Outside physical activity levels could not be controlled between testing sessions.
- The use of a handheld dynamometer for testing muscle strength is dependent on examiner skill and strength.
- 30 seconds of rest time was inserted between every 7-8 pitches in an attempt to simulate game conditions and allow for testing of average velocity and perceived exertion.
Practical Implications & Additional Thoughts
No players in the present study demonstrated fully recovered lower body musculature by the Little League approved return to pitching day. Based on these findings alone, it is not recommended that Little League baseball revise their guidelines. Further evidence showing a correlation to injury would be needed before widespread changes are made. However, the present study does suggest that adhering to these guidelines does not ensure adequate muscle recovery. Perhaps, performance and injury risk could be improved by providing pitchers with 1-2 additional days of rest between games.
The stride leg musculature showed a greater decline in strength following throwing. Also, older players showed greater decrements following the throwing session. This may indicate older players are more dependent on their lower body to generate forces during throwing. This is the period during development when young athletes could benefit from an individualized strength training program targeting the lower body, core, and upper body. Improved lower body muscular strength and endurance may improve recovery between bouts of pitching in these young athletes. Future studies should investigate the effects of a lower body strength training program on pitching mechanics and muscle recovery following throwing.
Perhaps the most important finding from the present study was the fact that athletes who specialized in baseball recovered more slowly than those who played multiple sports. Playing year-round, playing on multiple teams, specializing in a single sport, and exceeding Little League pitching guidelines should all be discouraged. With increased throwing volume comes increased arm fatigue and risk for injury2. Recovery between pitching sessions and time off from throwing during the year are critical for the health of youth baseball players. This study is one more highlighting the importance of rest and recovery for our youth athletes.
- Pei-Hsi Chou P, Huang Y-P, Gu Y-H, et al. Change in pitching biomechanics in the late-inning in Taiwanese high school baseball pitchers. J Strength Cond Res. 2015;29(6):1500-1508.
- Fleisig GS, Andrews JR, Cutter GR, et al. Risk of serious injury for young baseball pitchers: A 10-year prospective study. Am J Sports Med. 2011;39(2):253-257. doi:10.1177/0363546510384224.