Focusing on building and maintaining lean muscle should be a main concern in any fitness routine—not just for how you look. Once you hit 30, you begin to lose about 3% to 8% of your muscle mass every ten years in a process known as sarcopenia. If you ignore this, it might lead to issues with balance, increased chances of falling, and struggling with everyday tasks like climbing stairs. The upside is, with a solid strategy, you can tackle muscle loss effectively.

To enhance your workout strategy, we consulted with Mr. America Jason Kozma, CPT, a personal trainer based in Los Angeles, who reveals his effective 21-day bodyweight challenge designed to help build lean muscle. Best of all, you don’t need any high-end gym equipment to get started.

Kozma explains that the key to muscle building with bodyweight exercises lies in several crucial principles: progressive overload, time under tension, mechanical tension and volume, proper muscle recovery, and establishing a mind-muscle connection.

“Challenge muscles over time by increasing reps, time under tension (e.g., slower reps), or advancing the move (progress from regular to decline push-up),” Kozma explains. “Slow, controlled movements stimulate hypertrophy. Add pauses or extend the lowering phase to increase difficulty.”

Kozma recommends blending intensity—training near failure—with sufficient volume. Aim for 3 to 4 sets of 8 to 15 reps per exercise. In addition, weave in recovery days “so the body can rebuild stronger.”

Below, Kozma breaks down the ultimate 21-day bodyweight challenge to fast-track muscle growth.

The 21-Day Bodyweight Challenge to Build Muscle

The structure Kozma recommends is outlined below:

• 3 Strength Days
• 2 Accessory Days
• 2 Active Recovery or Rest Days

5 Strength Tests Every Woman Over 45 Should Be Able to Ace

Weekly Schedule (Repeat Weekly)

• Day 1: Full-Body Strength A
• Day 2: Core + Mobility
• Day 3: Lower-Body Focus
• Day 4: Active Recovery
• Day 5: Full-Body Strength B
• Day 6: Upper Body + Core
• Day 7: Rest

These 6 Bodyweight Moves Build Core Strength Faster Than Planks After 40

Full-Body Strength A

• Jump Squats: 3 sets of 12 reps
• Pushups (feet elevated for advanced level): 3 sets of 10–15 reps
• Glute Bridges (single-leg for advanced level): 3 sets of 10 reps per leg
• Forearm Plank Shoulder Taps: 3 sets of 20 taps
• Slow Bodyweight Rows (use a table or TRX, if available): 3 sets of 8–10 reps

4 Fitness Challenges Every Man After 40 Should Master

Core + Mobility

• Dead Bug: 3 sets of 10 reps
• Side Plank with Leg Raise: 3 sets of 10 sec + 5 leg lifts
• Cat-Cow: 2 sets of 10 reps
• World’s Greatest Stretch: 2 rounds per side
• Hollow Hold: 3 sets of 20 seconds

Lower-Body Focus

• Bulgarian Split Squats: 3 sets of 8–10 reps per leg
• Step-ups: 3 sets of 10 reps per leg
• Wall Sit: 3 sets of 30–45 seconds
• Calf Raises: 3 sets of 20 reps
• Glute March: 2 sets of 15 reps per side

Active Recovery

• 30—45 minutes of a low-intensity walk, bike ride, or swim
• Optional: foam rolling or 10–15 minutes of yoga

Full-Body Strength B

• Tempo Squats (3 seconds down, 1 second pause): 3 sets of 10 reps
• Pike Pushups: 3 sets of 8–10 reps
• Hamstring Walkouts: 2 sets of 10 reps
• Bear Crawl (Forward/Back): 3 rounds of 20 seconds
• Supermans: 3 sets of 15 reps

Upper Body + Core

• Diamond Pushups: 3 sets of 8–12 reps
• Inverted Rows or Towel Rows: 3 sets of 8–10 reps
• Plank to Elbow Tap: 3 sets of 20 taps
• Leg Raises: 3 sets of 10–15 reps
• Wall Walk: 3 sets of 15–30 seconds

Alexa Mellardo