Those four moves cover a lot. You get a push pattern, a knee-dominant squat, some anterior core work, and light conditioning. But a full, resilient body also needs pulling, hip hinging, overhead control, lateral and rotational strength, and small stabilizers. Here is what would be undertrained or missed.

1) Pulling muscles of the upper body

• Lats, mid and lower traps, rhomboids, rear delts, and biceps get little stimulus.
• Likely outcomes: rounded shoulders, cranky neck, elbow aches from push dominance, weaker posture under load.

2) Hip hinge and the true posterior chain

• Hamstrings, glute max in hip extension, and spinal erectors are not challenged by squats alone.
• Likely outcomes: low back tightness from fatigue rather than strength, quad-dominant patterning, slower sprinting and jumping power.

3) Overhead strength and scapular upward rotation

• Delts overhead, lower traps, and serratus in upward rotation receive minimal work.
• Likely outcomes: sticky shoulders overhead, limited range, higher risk of impingement during daily reaching.

4) Rotator cuff external rotation and scapular stability

• Infraspinatus and teres minor, plus precise scapular control, are not targeted by standard push ups.
• Likely outcomes: shoulder discomfort, poor throwing or pressing mechanics.

5) Lateral chain and single-leg stability

• Glute medius, adductors, and the quadratus lumborum stabilize side-to-side movement. Jumping jacks touch abduction, but not loaded or single-leg control.
• Likely outcomes: knee cave in squats, hip drop while walking or running, IT band irritation.

6) Rotational and anti-rotation core

• Sit ups bias spinal flexion and the rectus abdominis. Obliques and transverse abdominis need rotation, anti-rotation, and bracing.
• Likely outcomes: weaker force transfer from legs to arms, back discomfort during twisting tasks.

7) Lower leg balance, especially the front of the shin

• Calves get some work with jumping jacks, but tibialis anterior and intrinsic foot muscles are mostly skipped.
• Likely outcomes: shin splints tendency, poor deceleration, less ankle resilience.

8) Neck and grip

• Deep neck flexors and extensors, along with forearm flexors and extensors, get little direct work.
• Likely outcomes: tech-neck fatigue, limited grip endurance that carries over to sports and work.

9) End-range mobility and joint variety

• Hips, thoracic spine, and ankles do not see enough varied ranges of motion with those four alone.
• Likely outcomes: plateaus in squat depth, stiff mid-back, limited ankle dorsiflexion.

10) Power, elasticity, and planes of motion

• Power in horizontal or rotational planes and elastic qualities beyond simple jumping are undertrained.
• Likely outcomes: good general fitness but poor change-of-direction pop and rotational athleticism.

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Simple add-ons to cover the gaps

No gym required. Sprinkle these into your week to round things out.

• Pulling
  • Table rows or low bar body rows
  • Doorway towel isometric rows
  • If available, hang and do assisted pull ups
• Hip hinge
  • Hip hinge drill against a wall
  • Glute bridge and single-leg bridge
  • Sliding hamstring curls on socks or towels
• Overhead control and scapula
  • Wall slides
  • Pike handstand holds or elevated pike push ups
  • Push up plus for serratus
• Lateral and single-leg
  • Side lunges or Cossack squats
  • Single-leg balance holds and single-leg reaches
• Rotation and anti-rotation
  • Side plank and hard-style plank
  • Dead bug and bird dog
  • Tall-kneeling or half-kneeling anti-rotation press if you have a band, otherwise long-lever side plank variations
• Lower leg and feet
  • Standing calf raises and bent-knee calf raises
  • Wall tibialis raises
  • Short-foot drills and barefoot balance work on a safe surface
• Neck and grip
  • Chin tucks and prone neck extensions with light range
  • Timed hangs or farmer carries with water jugs or tote bags
• Mobility
  • Ankle rocks, couch stretch, thoracic rotations, shoulder CARs

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A minimal weekly template

Use your four staples as the base, then add one gap-fixer each day.

• Day 1: Push ups, squats, sit ups, jumping jacks, plus table rows
• Day 2: Push ups, squats, sit ups, jumping jacks, plus glute bridges and hamstring slides
• Day 3: Push ups, squats, sit ups, jumping jacks, plus side lunges and side plank
• Day 4: Push ups, squats, sit ups, jumping jacks, plus wall slides and push up plus
• Day 5: Push ups, squats, sit ups, jumping jacks, plus calf raises and tibialis raises

Short sessions still work. Two or three sets per add-on is enough to close most gaps.

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Bottom line

Push ups, sit ups, squats, and jumping jacks can build a decent base. Without pulls, hinges, overhead control, lateral and rotational work, and small stabilizers, you will develop imbalances. Add a few simple patterns each week and you will keep the engine while maintaining the chassis that lets you move well, stay pain free, and keep progressing.