Long-Term Effects of NASM-OPT Periodized Training on Lower-Limb Strength, Explosive Power, and Stretch-Shortening Cycle Function in Adolescent Athletes

Table 2. Lower-limb strength training protocols for OPT and CON groups.

Tier	Phase	OPT		CON
Tier	Phase	Content	Load	Content	Load
Stabilization	Stabilization Endurance (4 wks)	Single-leg balance extension Single-leg deadlift Single-leg calf raise Lunge squat	BW, 3×30s 15%, 3×10	Barbell back squat Barbell deadlift Barbell high pull	30%, 3×15
Strength	Strength Endurance (6 wks)	Dumbbell Lunge Dumbbell Squat Dumbbell Single-leg deadlift	30%, 3×15	Barbell back squat Barbell deadlift Barbell power clean	60%, 3×15
	Hypertrophy (6 wks)	Barbell Squat Seated Leg Extension Seated Leg Curl	60%, TF×2	Barbell back squat Barbell deadlift Barbell power clean	80%, 5×10
	Maximal Strength (6 wks)	Barbell Squat Barbell Deadlift Barbell Hip Thrust	100%/95%/90% 3×1/2/3	Barbell back squat Barbell deadlift Barbell power clean	90%, 3×6
Power	Power (4 wks)	Squat Jump (5 Vertical Jumps) Lunge Jump (5 Vertical Jumps) Barbell Power Clean (5 Vertical Jumps*)	75%, 3×6	Barbell back squat (5 Vertical jumps) Barbell deadlift (5 Vertical jumps) Barbell power clean (5 Vertical jumps*)	80%, 3×10

BW = Body weight; TF = to failure. Complex training: Each set of heavy resistance exercise was immediately followed by 5 plyometric repetitions with 30-second rest interval between exercises.