Most people treat ab training like an afterthought.
They rush through a few crunches at the end of their workout and wonder why their midsection never changes.
But legendary bodybuilding coach Charles Glass, with over 40 years of training experience, has a different approach—one that transforms cores from flat to defined in just 20 minutes, three times per week.
In a recent training demonstration, Glass revealed his complete ab routine that targets everything from upper abs to obliques to that stubborn lower section most people can’t seem to crack.
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Why Most Ab Workouts Fail
Glass has witnessed the same mistake countless times throughout his decades coaching elite athletes and everyday gym-goers alike.
Most people leave abs for last. They rush through it, do a few crunches, and wonder why their midsection never changes.
The problem isn’t effort—it’s intention. Movement without purpose builds nothing.
Glass emphasizes that building a defined six-pack requires controlled, precise exercises that tighten, define, and build real strength. No fancy machines needed, just proper technique and consistency.
The Complete 20-Minute Ab Routine
Glass structures his ab training around three fundamental exercises that cover every critical area of the midsection.
Standing Cable Crunches: Upper Ab Definition
This exercise specifically targets the rectus abdominis—the muscle responsible for that coveted six-pack appearance.
Proper execution is everything:
- Grab the rope attachment with both hands, positioning it above your head
- Engage your core before initiating movement
- Bend at the waist, bringing elbows toward thighs while keeping hips completely stationary
- Squeeze hard at the bottom for maximum contraction
- Return slowly to starting position with complete control
The key is using abs to power the movement, not momentum or body weight. Control beats speed every single time.
Hanging Leg Raises: Lower Ab Activation
Lower abs remain notoriously difficult to develop, but Glass has refined his technique over four decades to eliminate common mistakes.
The biggest issue? Excessive swinging that removes tension from the target muscle.
You lift, you lean forward. When you let your legs down, you lean back. Why? It stops the swing.
Glass teaches a counterbalance technique: lean slightly forward as legs rise, then lean back as they descend. This simple adjustment eliminates momentum and keeps constant tension on lower abs.
Another critical detail—keep legs relaxed. When demonstrating proper form, Glass noted that stiffening legs increases swing and reduces ab engagement. Relaxed legs allow for smoother, more controlled movement with better muscle connection.
Seated Knee Raises: Isolated Lower Ab Work
For those who struggle with hanging exercises or want additional lower ab volume, Glass recommends seated knee raises on a bench.
That’s all lower ab right there. Now you can put a weight between her feet to get more pressure on the lower ab.
This exercise allows precise control and easy progression by adding weight between feet as strength improves.
Russian Twists and Windshield Wipers: Oblique Development
Complete core development requires targeting obliques—the muscles along your sides that create that coveted V-taper and complete the six-pack look.
Glass teaches two variations depending on fitness level.
Floor version (beginner to intermediate):
- Lie on floor with legs straight up
- Swing legs side to side, moving only from hips
- Pause at center position
- Never let feet touch floor—maintain constant tension
- Focus on hip movement, not torso rotation
Hanging version (advanced):
- Position body at 45-degree angle while hanging
- Move legs side to side with same controlled motion
- Keep torso stable—movement comes exclusively from hips
- Contract obliques hard at each side
The distinction Glass makes is crucial: this isn’t twisting your torso, it’s isolating hip movement while keeping everything else locked in position.
Training Frequency That Actually Works
When asked about optimal training frequency, Glass’s answer surprises many who believe abs need daily work.
I do at least three times a week. And I do abs for like a half hour.
Three 30-minute sessions per week provides sufficient stimulus for growth while allowing adequate recovery. Glass notes that on off days, he focuses on cardiovascular training instead.
This approach—intense, focused sessions with recovery built in—produces far better results than daily half-hearted attempts.
The Difference Between Training and Effective Training
Glass distinguishes between simply moving through exercises and actually transforming your physique.
A lot of people think they know how to train until they actually join the site and start to do the program. Anyone can train. Everyone knows how to train. But to actually hone in on those muscle groups that you need to hone in on to make your body look different.
His methodology emphasizes muscle awareness—developing the mind-muscle connection that separates mediocre results from dramatic transformation.
Whether working with professional bodybuilders or complete beginners, Glass applies the same principle: quality execution targeting specific muscle groups produces visible change.
Progressive Overload for Continuous Results
As with any muscle group, abs require progressive challenge to continue developing.
Glass recommends several progression methods:
- Add weight to cable crunches and seated raises
- Increase time under tension by slowing tempo
- Progress from floor to hanging variations of exercises
- Extend pause duration at peak contraction points
The beauty of this system is its scalability. Beginners can start with bodyweight floor exercises, while advanced trainees can add significant resistance and progress to challenging hanging variations.
What Makes This Approach Different
After 40 years coaching everyone from elite bodybuilders to everyday fitness enthusiasts, Glass has refined his approach to what actually produces results.
His system works because it addresses the real problems:
- Eliminates momentum that steals tension from target muscles
- Focuses on controlled movement over meaningless repetitions
- Targets all three ab regions instead of just upper abs
- Provides clear progression paths from beginner to advanced
- Requires minimal equipment that’s available in any gym
Most importantly, Glass emphasizes that this routine works for everyone—male or female, young or experienced.
My program is especially for every person. I don’t care who it is, male or female, because we can bring it out. So it’s designed for everyone.
Three focused 20-minute sessions per week following Glass’s precise techniques will tighten your waistline, define your six-pack, and build genuine core strength. No rushing, no afterthought training—just purposeful movement that transforms your midsection.
