Iron Engine: Squat & VO₂ Hybrid System

Program Description

This 7-week hybrid programme is designed to improve VO₂ max, rebuild running capacity, and maintain strong squat performance while protecting knee health. It uses a sustainable structure of three sessions per week (Monday, Wednesday, Friday or Saturday) and is built to be repeated year-round with gradual progression. The weekly structure is consistent throughout the cycle: Day 1 – Squat + VO₂ max intervals + reverse sled drags Day 2 – Zone 2 aerobic base + accessories Day 3 – Tempo/threshold run + posterior chain + sled work Every session begins with a structured warm-up to reduce injury risk and improve output. This should include 5–10 minutes of incline treadmill walking, easy cycling, or rowing, followed by dynamic mobility for hips, ankles, and hamstrings, then 2–3 short easy jog intervals to prepare for impact. This is especially important when combining running with heavy lower body strength work. Weeks 1–2 are the adaptation phase. Running volume and intensity are conservative to allow joints and connective tissue to readjust. VO₂ work is primarily low impact (bike, rower, or controlled treadmill intervals), squats are moderate intensity, and reverse sled drags are introduced at light to moderate loads to build knee resilience, quad strength, and work capacity without excessive joint stress. Zone 2 cardio is kept conversational to establish a strong aerobic base. Weeks 3–4 transition into performance development. VO₂ intervals become more structured on the treadmill with a slight incline to reduce joint impact. Squat intensity increases moderately while volume remains controlled to manage fatigue. Continuous tempo running is introduced to improve lactate threshold and cardiovascular efficiency. Reverse sled drags progress in load or distance and serve both as knee prehab and low-impact conditioning. Weeks 5–6 are the peak training phase. VO₂ max intervals become longer and more demanding, driving the largest cardiovascular adaptations. Squats move into heavier but submaximal ranges to maintain strength without compromising recovery. Zone 2 duration increases to 45–50 minutes, and tempo efforts extend to longer sustained runs. Heavier reverse sled drags are emphasised for knee durability, muscular endurance, and hybrid conditioning support. Week 7 is a mandatory deload to consolidate gains and reduce accumulated fatigue. Intensity and volume are reduced across all sessions, with lighter squats, easy aerobic work, and optional very light sled drags for recovery and blood flow. No maximal lifting or hard intervals are performed. After the deload, the programme is repeated from a slightly higher base. Progression is achieved by gradually increasing squat loads, extending Zone 2 duration (up to around 60 minutes), slightly increasing interval speed, or adding sled load or distance. Only one primary variable should be progressed per cycle to maintain recovery and joint health.

Program Overview