Prompt Title: Workout

Good afternoon! Here's a workout protocol designed to meet your criteria. This program consists of 4 workouts per week, with each session lasting under 60 minutes. It emphasizes functional movements to optimize lean body mass.

Warm-up (10 minutes) Perform each of these exercises for 30 seconds, followed by a 30-second rest. Repeat the circuit twice.

1. Jumping jacks
2. Bodyweight squats
3. High knees
4. Arm circles
5. Hip circles

Workout (4 Days per Week)

Day 1: Vertical Push/Pull

1. Pull-ups: 4 sets of 8-10 reps
2. Push-ups: 4 sets of 10-12 reps
3. Dips: 3 sets of 8-10 reps
4. Inverted rows: 3 sets of 8-10 reps
5. Standing dumbbell shoulder press: 3 sets of 10-12 reps
6. Lat pulldown: 3 sets of 10-12 reps

Day 2: Squat/Hinge

1. Goblet squats: 4 sets of 10-12 reps
2. Romanian deadlifts: 4 sets of 10-12 reps
3. Walking lunges: 3 sets of 12-14 reps (each leg)
4. Glute bridges: 3 sets of 12-15 reps
5. Bulgarian split squats: 3 sets of 8-10 reps (each leg)
6. Plank: 3 sets, hold for 60 seconds

Day 3: Rest

Day 4: Horizontal Push/Pull

1. Bench press: 4 sets of 8-10 reps
2. Bent-over rows: 4 sets of 8-10 reps
3. Push-ups: 3 sets of 10-12 reps
4. Seated cable row: 3 sets of 10-12 reps
5. Dumbbell chest fly: 3 sets of 10-12 reps
6. Face pulls: 3 sets of 12-15 reps

Day 5: Squat/Hinge

1. Front squats: 4 sets of 8-10 reps
2. Single-leg deadlifts: 4 sets of 10-12 reps (each leg)
3. Step-ups: 3 sets of 12-14 reps (each leg)
4. Kettlebell swings: 3 sets of 12-15 reps
5. Leg curls: 3 sets of 10-12 reps
6. Side plank: 3 sets, hold for 45 seconds (each side)

Days 6-7: Rest

Cooldown (5 minutes) Finish each workout session with gentle stretching and deep breathing exercises to help your body recover.

Remember to adjust the weights and intensity according to your fitness level. Progressively increase the resistance and/or reps as you get stronger. Make sure to maintain proper form and consult with a fitness professional if you're unsure about any exercise.