Old-School High-Intensity Training (HIT): Routines of Casey Viator, Mike Mentzer, and Clarence Bass

National Discount Nutrition April 21, 2025

High-Intensity Training (HIT) is making a serious comeback. Originally popularized in the 1970s and 80s by bodybuilding icons like Casey Viator, Mike Mentzer, and Clarence Bass, this old-school approach to training emphasizes brief, intense workouts that produce maximum muscle growth in minimal time.

In this article, we’ll dive into the philosophy behind HIT, break down the actual training routines of these legendary athletes, and explain why this timeless method still holds massive value for modern lifters.

What Is High-Intensity Training (HIT)?

High-Intensity Training (HIT) is a low-volume, high-effort resistance training style where each set is taken to momentary muscular failure. The concept was popularized by Arthur Jones, the inventor of Nautilus machines, and later refined by bodybuilders like Mike Mentzer and Casey Viator.

Key Principles of HIT:

Train Infrequently (2–4x per week)
Low Volume (1 working set per exercise)
High Effort (train to failure or beyond)
Slow Reps (control the weight both up and down)
Full-Body Focus or Split Routines
Progressive Overload is king

1. Casey Viator: The Colorado Experiment & Maximum Results

Casey Viator is arguably the most famous case study for HIT thanks to the legendary Colorado Experiment in 1973, supervised by Arthur Jones.

Highlights:

Gained 63 pounds of muscle in 28 days
Trained only every other day
Used Nautilus machines
Focused on full-body routines

Casey Viator’s HIT Routine (Colorado Experiment Sample):

Leg Press – 1 set to failure
Leg Extension – 1 set to failure
Leg Curl – 1 set
Pullover Machine – 1 set
Chest Press – 1 set
Lateral Raise – 1 set
Biceps Curl – 1 set
Triceps Extension – 1 set
Calf Raise – 1 set
Ab Crunch – 1 set

🕒 Total workout time? Around 30 minutes.

2. Mike Mentzer: Heavy Duty System

Mike Mentzer, a Mr. Olympia contender and intellectual powerhouse, took HIT to the extreme with his Heavy Duty system. He believed most people overtrain and under-recover.

Heavy Duty Training Features:

3–4 workouts per week max
Each muscle group trained with just 1-2 sets
Intensity-enhancing techniques like forced reps, negatives, and rest-pause

Mike Mentzer’s Chest and Back Workout:

Incline Machine Press – 1 warm-up, 1 set to failure
Flat Bench Dumbbell Fly – 1 set to failure
Pullovers (Nautilus or Dumbbell) – 1 set to failure
Pulldowns or Pull-Ups – 1 set to failure
Barbell Row – 1 set to failure

He often trained on a 2-day split:

Day 1: Chest, Back
Day 2: Legs, Shoulders, Arms
Rest 2–3 days between

3. Clarence Bass: The Lean HIT Machine

Clarence Bass, author of the “Ripped” series, wasn’t just strong—he was shredded year-round. He combined HIT with clean eating and a lifelong passion for body composition.

Unlike Mentzer, Bass used a slightly higher volume, but still trained with intensity and focus.

Clarence Bass Full-Body HIT Routine:

Squat or Deadlift – 1–2 sets
Leg Curl – 1 set
Bench Press or Dip – 1–2 sets
Pull-Up or Row – 1–2 sets
Overhead Press – 1 set
Barbell Curl – 1 set
Triceps Pushdown – 1 set

He trained 2–3 times per week, focused on perfect form, and often used slow reps to increase time under tension.

Benefits of Old-School HIT

✅ Time Efficient

HIT workouts typically last 30 minutes or less.

✅ Effective for Natural Lifters

With low volume and proper recovery, it's ideal for those not using performance-enhancers.

✅ Encourages Recovery

HIT emphasizes rest days—a crucial factor for growth.

✅ Mental Toughness

Training to true failure builds focus and grit.

Is Old-School HIT Right for You?

If you’re burnt out on high-volume training, or just want to gain muscle with less time in the gym, HIT might be your secret weapon. It’s especially powerful for busy professionals, older lifters, and those who value recovery and longevity.

Final Thoughts

Old-School High-Intensity Training isn’t just a relic of the past—it’s a timeless muscle-building method used by some of the most legendary physiques in bodybuilding history.

Whether you're following Casey Viator’s full-body blasts, Mike Mentzer’s Heavy Duty split, or Clarence Bass's disciplined approach, HIT offers a direct, no-BS path to strength and muscle.

Frequently Asked Questions (FAQ)

Q: Can HIT build muscle as effectively as traditional volume training?
A: Absolutely. For many, HIT can produce equal or better results due to better recovery and maximum effort per set.

Q: How often should I train with HIT?
A: Start with 2–3 full-body sessions per week, then adjust based on recovery and results.

Q: Do I need machines like Nautilus?
A: No. HIT principles apply with free weights, machines, or bodyweight.