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The True Meaning of “Using Your Legs” During Hitting

Hitting is hard, there is no question about it. It requires hitting a round object with another round object, squarely. Tell me that isn’t difficult to keep repeating!

Hitting a baseball successfully requires patience and proper timing. Previous research has utilized surface electromyographic (sEMG) technology to study the timing mechanisms during the baseball swing.

Previous research with sEMG has shown that the swing is initiated from the lower limbs. However, in that particular study, only 3 muscles of ONE lower limb were analyzed. This tells us the beginning of the story, but there are some missing parts.

In order for us as baseball coaches to truly study and understand movement, we should look at the differences between skilled and unskilled players.

In this study, there were multiple hypotheses:

  1. There will be a difference in the onset latency, peak latency, and peak amplitude of sEMG activity between skilled and unskilled players
  2. The timing of each phase during the swing motion will be different between skilled and unskilled players
  3. The variability of timing in each phase will be different. Specifically, skilled players will have less variability in their timing when compared to unskilled players

10 skilled and 10 unskilled athletes participated in this study. All of the skilled players had experience playing in college and had played baseball at least once a week once graduating from college. The unskilled players had experience swinging a baseball bat, but never received prior instruction from an outside source.

Each participant had sEMG nodes placed on both of their lower limbs (rectus femoris/upper leg, tibialis anterior/lower leg, and medial gastrocnemius/lower leg). High-speed cameras were also used during the swing to ensure proper data comparison with the sEMG.

Each participant took 60 swings. Of these 60 swings, 45 were “swing” trials, and 15 were “stopping” trials.

The swing trial required the participant to hit the ball that was tossed at them. The stopping trial required the participant to “stop” their swing as the tosser did NOT throw the ball.

In order to see “how much” each participant was using their legs, the researchers had each participant perform maximal voluntary isometric contractions after the 60-pitch trial. These data points will show their peak contraction, and then could be compared to the swing to determine a percentage of usage from the lower limbs.

For example, let’s say that my swing showed 80% amplitude compared to my maximal contraction, that would tell us that I am getting good lower-half engagement during the swing.

The swing was divided into 7 different phases:

  1. Waiting – the phase before a bodyweight shift
  2. Shifting – the initiation of bodyweight shift to the back leg
  3. Stepping – the initiation of the front leg releasing from the ground to move forward
  4. Landing – touchdown of the front foot
  5. Swing – the initiation of bat movement
  6. Impact – the time of ball contact
  7. Follow through – the time from ball contact to the finish of the swing

Results

As expected, the skilled baseball players shifted their body weight, stepped towards the ball path, and landed their front foot much earlier than the unskilled baseball players.

The start of the swing was much later in skilled players than the unskilled players. Unskilled players also had much greater variability in their swing time than the skilled players.

The peak amplitude of sEMG was much greater in skilled players than unskilled players. Interestingly, the front tibialis anterior (lower leg) had double the amount of activity.

The researchers demonstrated this as being part of a skilled player: once the front foot lands, skilled players don’t start to move forward and absorb force until they know that they are swinging at the pitch. Hence, the whole “staying back” phenomenon could be explained there.

Swinging with a PVC pipe can give a “feel” for timing and the “whip” through the zone

The unskilled players had a time latency much different than the skilled players. They did not sufficiently shift their weight to the back leg, and ultimately started their swing before the front foot even touched the ground. This could explain why there was so much variability in the swing timing.

These results do show that skilled players know how to properly time each phase of the swing motion. However, here are some limitations:

  • Timing could have been different if the thrower was throwing overhand rather than front tossing
  • Were skilled players using their “real swing” during experimental conditions?
  • If the researchers noted in their introduction how important the gluteal muscles are, how come they did not use any sEMG data?

Concluding this study, here’s what we should take away from it:

  • TAKE VIDEO! You now understand how the researchers separated the swing into 7 different phases. Are you starting your swing too early? Are you not shifting your weight properly?
  • Once you see where you are diffident, use constraint drills that FORCE you to work on one phase. For example, if you start your swing too early, work on drills that put you in front foot landing without your weight transferring (think of the Albert Pujols wide stance landing)
  • Each leg works independently of another. While bilateral strength training exercises have their place, unilateral training is more specific to the baseball swing. The back leg must be strong and stable to produce force, and the front leg must be strong and stable to absorb force as the trunk begins to rotate the bat through the hitting zone

Keep swinging,

Jarad Vollkommer, CSCS

Reference

Nakata, H., Miura, A., Yoshie, M., Kanosue, K., and Pudo, K. (2013). Electromyographic analysis of lower limbs during baseball batting. Journal of Strength and Conditioning Research 27(5), 1179-1187.

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