Table 3.

Studies that investigated the effects of plyometric training programs on strength performance.

Study	Sex	Age (Mean) and Competitive Level	n	Design	Training Protocol	Main Results
Martel, Harmer [42]	Women	Aquatic group: 14 yo control group: 15 yo	19	Randomized controlled trial; 6-week period intervention	Aquatic plyometric training (APT): 2 × week; 45 min. Power skips, spike approaches, single- and double-leg bounding, and squat jumps progressively increased from two times per session to five times per session. Bouts increased from 10 s to 30 s of maximal jump during the period. Depth jumps were performed involving three submerged boxes also progressively increasing the number of times session during the period. Control group (CG): A flexibility supervised program was conducted twice a week, consisting of three sets of 8–10 static stretches for 30 s each.	There were no significant differences in concentric peak torque in either the dominant or nondominant leg between the APT and traditional volleyball training groups at baseline. Similar significant improvements in concentric peak torque were observed in the dominant leg of both groups when comparing baseline values with those obtained after 6 weeks. The improvements in both groups were similar for knee extension and flexion at both 60º and 180º.
Hewett, Stroupe [44]	Women	15 yo	20	Case reports; 6-week period intervention	Experimental group had three sessions per week. The program followed three phases: technique phase (two first weeks), fundamentals phase (using a proper technique to build strength and power), and performance phase (focusing on achieving maximal jumping).	Isokinetic peak torque increased 26% in the non-dominant leg and 13% in the dominant leg. The hamstring-to-quadriceps muscle peak torque ratio increased 13% on the dominant side and 26% on the non-dominant side.
Mroczek, Superlak [53]	Men	21 yo 2nd league	16	Case reports; 6-week period intervention	Measuring muscle stiffness: Three measurements performed once per week over 6 consecutive weeks of plyometric training (before the warm-up): In week 0, week 4 (the effects of the training completed in week 3) and week 6 (the effects of the training carried out in week 5). Individual assessments lasted up to 4 min, and the participants underwent them in a random order.	The analysis of stiffness levels in the posterior parts of the thigh revealed significant differences between the points in the left and right limbs only in the posterior muscles. Significant differences were observed for the semitendinosus immediately before the experiment started, whereas the differences were insignificant in the fourth and sixth training sessions.
Bashir, SulehHayyat [55]	Men	N. R.	45 G1—plyometric training (15); G2—weight and plyometric (15); G3—control group (15)	Randomized controlled trial; 12-week period intervention	Group I and II underwent respective training programs for 3 days per week for 12 weeks under the instruction and supervision of the investigator. Group-I performed plyometric training with a training intensity of 65%–80% of their 1RM and the subjects of experimental Group-II performed a combination of weight and plyometric training with a training intensity of 65%–80% of their 1RM.	Differences in muscular strength between plyometric training and control groups were significant at the 0.05 level of confidence. No significant difference between plyometric and combination of weight and plyometric training groups (0.37) in muscular strength after the training program. Differences in muscular endurance between plyometric training and control groups and a combination of weight and plyometric training and control group were significant. No significant difference between plyometric and combination of weight and plyometric training groups on muscular endurance after the training program.

Yo: years old.