Baseball's lower-body focus has legs

When one thinks of baseball injuries, one naturally thinks of the upper extremities: the torn rotator cuff or ulnar collateral ligament, subacromial impingement, glenohumeral instability. But some of the biggest moments in the sport's history have involved injuries below the strike zone.

The drama of Kirk Gibson's pinch-hit home run to end game one of the 1988 World Series was heightened by the fact that it was a walk-off shot by a man who could barely walk; Gibson had sat out the entire game to that point with a hamstring strain in his left leg and an extremely painful sprained ligament in his right knee. Many Red Sox fans believe it was Bill Buckner's bad ankles, not bad luck, that cost the Red Sox game six of the 1986 World Series when a ground ball scooted through the first baseman's legs. An unprecedented procedure to temporarily stabilize the dislocated peroneal tendon in Curt Schilling's right ankle allowed the Sox ace to win game six of the 2004 American League Championship Series, from which Schilling's famous blood-soaked sock is now in the Hall of Fame.

It's true that baseball's most basic actions of throwing and hitting are performed using the upper extremities, and that the majority of baseball injuries occur in the upper body. But as any student of biomechanics knows, upper extremity motion rarely occurs in isolation from the rest of the body, and baseball is no exception. The lower extremities and trunk provide extra momentum and power during hitting and throwing, as well as stability and agility during fielding and base running.

It's taken a while for these concepts to make their way into research on the biomechanics of baseball and into the training and conditioning drills performed by players. But, slowly, the idea is gaining legs.

“It's funny how people don't really talk about the lower extremities in baseball, but the upper and lower body are so interrelated. There's that transfer of force up the trunk and out the upper extremities, so all of that kinetic linking comes into play,” said Sue Falsone, PT, ATC, physical therapist for the Los Angeles Dodgers and director of performance physical therapy at Athletes' Performance in Tempe, AZ. “But I think maybe in the last five to ten years more people have been looking at that kind of thing. Athletes and clinicians alike are coming around to the fact that it's a bigger picture than just the shoulder and elbow.”

Falsone was a guest speaker in January at the annual “Injuries in Baseball” course held by the American Sports Medicine Institute (ASMI), the Birmingham-based research organization that is affiliated with surgeon-to-the-stars James Andrews, MD, and a number of major league players. Although the proceedings of the three-day course were heavily weighted toward the upper body, they did include nine different presentations on lower extremity topics ranging from ankle tendinitis to hamstring strains.

Not surprisingly, ASMI has been at the forefront of the recent wave of research examining the total-body mechanics of baseball movements, in particular the pitching motion. Two 2001 papers^1,2 from the institute identified lead knee extension velocity and pelvis angle at the time of ball release were significantly related to ball velocity, as was pelvic angular velocity from front foot contact to maximum shoulder external rotation. A 2005 study³ of within-pitcher variations in velocity found that increased trunk tilt at ball release was associated with higher velocities.

From the mound up

More recently, a January 2007 ASMI study⁴ again pointed to trunk tilt as a key element of pitching, this time with regard to muscle fatigue. The investigators analyzed 10 collegiate pitchers who threw 15 pitches per inning for seven to nine innings during a simulated baseball game, and found that ball velocity in the final two innings pitches was significantly lower than in the first two innings. The only kinematic variable that corresponded to this drop in velocity was that the trunk position was significantly closer to vertical in the later innings. Although the change in knee flexion angle at the time of ball release was not significant (41±13º in the first innings vs 39±16º in the later innings), these results and those of the 2001 research suggest that knee extensor fatigue may contribute to the change in trunk position.

“For a baseball pitcher, one of most important things is having good endurance and strength in the legs,” said Rafael F. Escamilla, PT, PhD, a professor of physical therapy at Cal State University in Sacramento and lead author of the 2007 study. “Once your legs go, your ability to distribute the energy is diminished.”

That isn't news to Hall of Famer pitchers Gaylord Perry and Nolan Ryan, both of whom pitched into their forties but have said their legs gave out before their arms did. And later generations of pitchers are taking that lesson to heart. Regardless of the extent to which Roger Clemens' success was or was not aided by performance enhancing drugs, pitchers and biomechanists alike respect the dedication with which Clemens has strengthened his trunk and lower body. Two-time Cy Young award winner Johan Santana, who doesn't have the massive leg musculature of Clemens or other power pitchers, nonetheless last season would devote the first of his four days between starts to lower body strengthening under the direction of Minnesota Twins strength and conditioning coordinator Perry Castellano (Santana was traded to the New York Mets in the off season).

“If you looked at Major League Baseball 25 years ago, you saw very little weight training, and now these guys are lifting year round,” said Robert Mangine, PT, ATC, director of the sports residency program for NovaCare Rehabilitation and head football athletic trainer for the University of Cincinnati, who presented on ACL and hamstring injuries in baseball at the ASMI course. “Part of it is that they feel they're getting a competitive edge, and another aspect is that they want to increase the length of their careers. Players today are smarter than they used to be, asking the right questions about what happens if I get hurt and finding the best options to stay competitive.”

Setting up the rotation

Additional research from ASMI presented in February at the American Physical Therapy Association's Combined Sections Meeting suggests that, as with a golf swing, range of motion in the lower body may be as important to pitching as strength or power. Investigators measured passive ROM at the hips and shoulders in 43 major league pitchers from the Tampa Bay Rays organization during spring training and found that hip external rotation on the dominant side (ipsilateral to the pitching arm) correlated with shoulder internal rotation on the same side, suggesting that the ability to externally rotate the hip allows for more power generation, which carries over into the shoulder motion and theoretically results in greater ball velocity. The researchers also found that hip adduction on the non-dominant side correlated with shoulder external rotation on the dominant side, suggesting that pitchers with a longer stride length give themselves more time to cock the throwing arm.

“The more we break down the throwing motion, the more we see the importance of the legs, in the push off and rotational component that's also part of most sports,” said Lenny Macrina, PT, CSCS, a physical therapist at Champion Sports Medicine in Birmingham, who presented the findings at the Combined Sections Meeting. “We're recognizing that what is causing the torso to turn is the muscles, so we have to work on the obliques, the core itself, and hip stability. If you can't maintain that stability then larger muscles like the glutes aren't going to be able to produce the force you need.”

Although pitching is typically thought of as a one-sided action, Macrina and colleagues found significant differences in passive ROM between the shoulders of each pitcher, but not between the hips. Seemingly counterintuitive, this finding actually corroborates that of an August study from Scottsdale, AZ, which reported no bilateral differences in mean active hip internal or external rotation in 147 elite tennis players and 101 male baseball pitchers.⁵ Clinically, the results suggest that asymmetrical hip ROM should be considered a red flag, and pitchers demonstrating this type of asymmetry would benefit from exercises to improve ROM on the tighter side.

It isn't only pitchers who are becoming leg men, however. Baltimore Orioles third baseman Melvin Mora credits his dramatic increase in offensive power between the 2001 and 2002 seasons (in which his season home run total jumped from seven to 19) to a conversation he had with former Mets teammate John Olerud about the importance of leg strength in hitting.⁶ Including leg work in his regular off-season conditioning routine helped Mora earn a starting job with the O's and earn All-Star accolades in 2003 and 2005.

“The energy's going to start from the ground, and if you don't have a good solid base for the trunk and upper extremities to rotate about then you're not going to be able to hit as effectively,” Escamilla said.

Although researchers are only beginning to examine the role of the lower extremities in the biomechanics of hitting, early results suggest that Olerud and Mora were very much on the right track.

In a study presented at the 2005 meeting of the American Society of Biomechanics,⁷ researchers from Miyagi, Japan, analyzed the batting motions of eight right-handed collegiate hitters and found that the legs and trunk accounted for the majority of angular momentum transferred in the early (single support) phase of hitting and for half of the angular momentum transfer in the first half of the double support phase. (In the last half of the double support phase, most of the angular momentum was generated by the arms and bat.)

At last year's ASB meeting, investigators from Toyota, Japan reported that the moment of the ground reaction forces acting on the legs of a batter is primarily responsible for the rotation of the body during hitting.⁸ In the study of 20 collegiate baseball players hitting balls tossed from three meters away, the largest ground reaction force was produced by the front leg, which in turn produced the largest moment arm and had the greatest rotational effect on the body.

Legging it out

And then there are baseball's more conventional applications of lower extremity mechanics, such as running the bases or making plays in the field—plays that, gone awry, can lead to ACL tears, hamstring strains, or ankle sprains.

To improve those speed and agility skills over a period of several weeks, as during spring training or in the weeks leading to the playoffs, a November study from Arizona State University⁹ suggests that a simultaneous combination of heavy resistance training and plyometrics (known as “complex training”) is more effective than either resistance or plyometric training alone. In a study of 45 junior college baseball position players randomized to one of the three interventions, complex training was associated with the greatest improvements in sprint speed, standing broad jump (which the authors say corresponds to baseball's horizontal movements such as taking off from a base or moving laterally to field a ball) and a T-agility test that involves multi-directional running.

Another advantage of complex training is that it takes less time than other explosive training modalities, at about 35 minutes per session compared to 50-60 minutes, said first author Dan Dodd, MS, CSCS, head strength and conditioning coach at Chandler-Gilbert Community College and a doctoral student in exercise and wellness at ASU.

“Our players usually start practice at 1 pm and go until 5:00 or 5:30 at night, so the last thing we want to do is fatigue them a lot more,” Dodd said. “This option helps keeps them fresh, and you still get the results you want.”

Touching them all

At baseball's most elite levels, practitioners say incorporating the lower extremities in conditioning and rehabilitation is a natural byproduct of an overall approach that is as tailored as possible, specific not just to a sport but to a position and to the individual needs of the athlete who plays that position.

“The simple take home message is know your anatomy, know how things fit together, know your sport and know your position,” Falsone said. “Everything else is really a bonus.”

To achieve that degree of specificity, she says, it helps to remember that there is strength in numbers.

“I'm not a baseball coach, so I try to look more at the movement patterns and then work with the skills coaches to focus on the sport-specific elements that will help the athlete on the field,” Falsone said. “It's got to be an athlete-centered model, a team approach, rather than one person feeling like they need to do everything.”

References

1.Stodden DF, Fleisig GS, McLean SP, et al. Relationship of pelvis and upper torso kinematics to pitched baseball velocity. J Appl Biomech 2001;17(2):164-172.

2.Matsuo T, Escamilla RF, Fleisig GS, et al. Comparison of kinematic and temporal parameters between different pitch velocity groups. J Appl Biomech 2001;17(1):1-13.

3.Stodden DF, Fleisig GS, McLean SP, Andrews JR. Relationship of biomechanical factors to baseball pitching velocity: within-pitcher variation. J Appl Biomech 2005;21(1):44-56.

4.Escamilla RF, Barrentine SW, Fleisig GS, et al. Pitching biomechanics as a pitcher approaches muscular fatigue during a simulated baseball game. Am J Sports Med 2007;35(1):23-33.

5.Ellenbecker TS, Ellenbecker GA, Roetert EP, et al. Descriptive profile of hip rotation range of motion in elite tennis players and professional baseball pitchers. Am J Sports Med 2007;35(8):1371-1376.

6.Berney, L. Mora Mora Mora: As power develops, Melvin Mora becomes everyday player. Outside Pitch, August 2002.

7.Miyanishi T. Transfer of angular momentum in the baseball batting. Presented at annual meeting of American Society of Biomechanics, Cleveland, OH; August 2005.

8.Yanai T. A mechanical cause of body rotation about the vertical axis in baseball batting. Presented at annual meeting of American Society of Biomechanics, Palo Alto, CA; August 2007.

9.Dodd DJ, Alvar BA. Analysis of acute explosive training modalities to improve lower-body power in baseball players. J Strength Cond Res 2007;21(4):1177-1182.