By Claire Shull, Thomas Robertson, Blake Doane

Hypothesis

•The researchers hypothesized that 8 weeks of biweekly plyometric training would enhance leg peak power, jump height, and sprint running velocity relative to players who maintained their normal in-season regimen.

Variables

•Independent Variable – lower limb plyometric training▫Hurdle and depth jump

•Dependent Variable – completive potential▫Peak Power output, jump force, jump

height, and lower limb muscle volume

Participants

•23 males•Single regional soccer team•All 19 years old•Randomly assigned to two groups

▫Control▫Experimental

•Experimental Group had 2 weeks prior to testing to familiarize with circuit

MethodsControl Group:

• January – March

• 5day/wk, 90 min practice

• 1 game per week

Experimental Group:

• Regular training (same as control group) PLUS;

• Additional plyometric training • 15 min warm-up + 30 minute workout

Methods

•Pre test, weekly testing, post test▫Data only collected on pre and post test

•2 day testing▫Day 1

Squat Jump (SJ) Countermovement Jumps (CMJ) Force-Velocity test

▫Day 2 Anthropometry Sprint performance

Experimental Plyometric Training:8 weeks (Jan– Mar) - 15 minute warm up + 30 minute workout

• Force velocity test ▫Evaluates leg PP (peak power output)

• Maximal pedaling velocity Vo

• Squat Jump and Countermovement Jump• 40-m sprint

▫Evaluates velocity during first step• 5-m velocity and maximal running velocity• Anthropometric assessments of lower limb

muscles

Results

External Validity• Generalizing to all junior soccer players during

in-season training

• They only chose one team

• Generalized to men only

• This is a strong validity but one way to strengthen it would be to test more in-season soccer teams in a variety of areas as well as testing women.

Construct Validity

•The face validity was strong because they measured what they wanted to measure. They didn’t get any measurements that would have changed the outcome of the tests.

•They didn’t have mono-methods testing because they tested in a variety of ways.

•Overall, the construct validity was strong. They new what they wanted to test and the results supported the hypothesis.

Internal Validity

•There is both covariance and temporal precedence which along with random assignment leaves only social interaction threats.▫R O X O▫R O O

•Possible threats could come up like diffusion or imitation or resentful demoralization but based on the results nothing seemed like it came into effect.

Discussion

•Some threats that could have happened were the control groups weren’t doing as well as the experimental groups because maybe the control groups weren’t getting the same playing time as the experimental group as a result of the experimental group is faster and stronger than the control group.