Plyometrics

Overview

Plyometric training (also called "jump training" or "plyos") uses explosive movements that employ the stretch-shortening cycle (SSC) — a rapid eccentric (lengthening) muscle action immediately followed by a concentric (shortening) contraction. Examples include countermovement jumps, box jumps, hopping, bounding, and step-up jumps. While traditionally associated with athletic performance, age-adapted plyometric training has emerged as a safe and effective intervention for older adults and cardiac patients, specifically targeting the rapid force production capacity that declines faster than maximal strength with aging. For the over-50 cardiac patient, plyometrics — when properly regressed — addresses a critical functional need: the ability to recover balance after tripping, which depends on power (not just strength). ^[raw/cardiac-recovery-fitness-protocol-deep-research.md]

Key Facts

Modality type: Power / explosive resistance
Impact classification: Moderate-to-high impact (can be regressed to low-impact)
Primary mechanism: Stretch-shortening cycle (SSC) — elastic energy storage and rapid force development
Key outcome: Muscle power (force × velocity), which declines 3–4% per decade after age 50 vs. 1–2% per decade for maximal strength
Evidence in older adults: A 2018 systematic review in Sports Medicine (Vetrovsky et al.) found plyometric training safe and effective in adults ≥60 years; a 2020 RCT (Van Roie et al.) showed age-adapted plyometrics improved power and functional capacity more than traditional RT in men aged 65–80
Phase applicability: Phase III (low-intensity drills) through Phase IV (progressive loading)
Evidence grade: Medium — growing evidence base in older adults; limited direct data in cardiac-specific populations

How Plyometrics Work: The Stretch-Shortening Cycle

Eccentric phase (loading): The muscle-tendon unit is rapidly stretched (e.g., lowering into a squat before a jump). Elastic energy is stored in the series elastic component.
Amortization phase (transition): The brief pause between eccentric and concentric phases. Shorter = more power output.
Concentric phase (unloading): The muscle contracts explosively, releasing stored elastic energy plus active contraction force.

The SSC allows the muscle to produce more force than a purely concentric contraction — this is the mechanism that makes plyometrics uniquely effective for power development.

Cardiac Application and Dosage

Age-Adapted Protocol (Based on Van Roie et al., 2020)

The key principle for cardiac patients is progressive exposure to impact and speed: ^[raw/cardiac-recovery-fitness-protocol-deep-research.md]

Stage	Weeks	Exercises	Intensity	Rest Between Reps
1 — Introduction	1–3	Step-ups (no jump), partial squats, wall-supported hops	Regular speed, no jump	5 sec
2 — Submaximal	4–6	Forward step-up jumps, lateral step-up jumps	Fast eccentric → submaximal jump	5 sec
3 — Maximal	7–9	Countermovement jumps, consecutive step-up jumps	Fast eccentric → maximal jump	5 sec
4 — Advanced	10–12	CMJ with pre-hops, single-leg hops, low box jumps	Maximal effort, minimal rest	No rest between reps

Frequency: 3×/week, non-consecutive days (48–72h recovery between sessions) Sets × Reps: 2–4 sets × 6–20 reps (progress from high-rep/low-intensity to low-rep/maximal)

Phase-Based Integration

Phase	Plyometric Load	Supervision	Notes
Phase II	Not recommended	—	Focus on aerobic base and basic RT first
Phase III	Stage 1–2 only (no impact)	Spot-check	Step-ups, supported hops; RPE ≤13
Phase IV	Stage 3–4 (progressive impact)	Self-monitored with periodic reassessment	Full progression; RPE ≤15

Hemodynamic Safety

BP spike on landing: The deceleration phase of a jump produces a brief BP spike. This is transient but can be significant in patients with uncontrolled hypertension. Ensure BP is well-controlled (<140/90) before initiating plyometrics.
Valsalva risk: High — the explosive nature of plyometric movements frequently triggers involuntary breath-holding. Explicit coaching: "exhale on the jump, inhale on the landing."
Ground reaction forces: Countermovement jumps produce 2–3× bodyweight in ground reaction forces. Begin with low-amplitude movements (small hops) and progress gradually.
Stopping criteria: Standard CR criteria apply — discontinue if SBP > 200 mmHg, DBP > 110 mmHg, or if exertional symptoms appear.

Benefits for the Over-50 Cardiac Patient

Fall prevention: Rapid force production is the primary determinant of whether a person can recover balance after tripping. Plyometric training specifically targets this capacity — maximal strength alone does not.
Bone density: The impact forces from jumping provide osteogenic stimulus, counteracting the bone loss that accelerates after age 50 (particularly relevant for patients on long-term corticosteroids).
Functional power: Chair rising, stair climbing, and walking speed all depend on muscle power more than maximal strength. Plyometrics improve these functional outcomes more than slow-speed resistance training.
Neuromuscular activation: Plyometric training improves the rate of motor unit recruitment, enhancing the speed and coordination of muscle responses.

Contraindications and Precautions

Uncontrolled hypertension (SBP >160 or DBP >100): BP spikes on landing may be dangerous. Stabilize BP before initiating plyometrics.
Severe osteoarthritis (knees, hips, ankles): Impact forces may aggravate joint pain. Substitute with non-impact power training (rapid step-ups without leaving the ground).
Severe osteoporosis (T-score < -3.0): Fracture risk from impact. Use only Stage 1–2 (no jumping) exercises.
Balance impairment: Patients who cannot stand on one leg for 10 seconds should not perform unilateral plyometric drills.
Recent cardiac event (<3 months): Plyometrics are not appropriate in early Phase II. Build aerobic and basic RT foundations first.
Beta-blocker patients: Blunted HR response means RPE is the sole intensity guide. Patients may not feel their HR climbing — emphasize "stop if you cannot maintain maximal quality on each rep."

[[resistance-training-entry-timeline]] — Clinical timelines for starting power-type exercise post-MI/PCI/CABG
[[calisthenics]] — Bodyweight resistance training; plyometric progressions using bodyweight
[[valsalva-maneuver]] — Breath-holding risk during explosive movements
[[aerobic-exercise-prescription]] — RPE-based intensity prescription for high-effort exercise
[[low-impact-cardio-modalities]] — Low-impact alternatives for patients who cannot tolerate plyometric impact