1. By Claire Shull, Thomas Robertson, Blake Doane

2. 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.

3. 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

4. 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

5. Methods Control 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

6. 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

7. 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 V o 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

8. Results

9. 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.

10. 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.

11. 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.

12. 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.