4 Workout Strategies Debunked By Science

It seems like there’s always a new “secret” workout strategy claiming to be the next big thing for muscle growth or fat loss. Some of them stick around for years, even after science steps in and points out the flaws. If you’ve ever found yourself sticking to certain workout beliefs because “that’s what everyone does,” this article might surprise you.

We’re going to dive into four popular workout strategies that have been debunked by science, so you can spend your time and energy on things that actually work. And by we, BOXROX actually means to lean on the expertise from Milo Wolf. Dr Milo Wolf shares his invaluable knowledge on a YouTube channel ranging from hypertrophy and strength training to losing fat.

So let’s clear up the confusion!

Note: all scientific literature mentioned can be accessed at the end of the page.

4 Workout Strategies Debunked By Science

1. Time Under Tension (TUT)

You’ve probably heard this one from every bodybuilder and fitness influencer: focus on how long your muscles stay under tension rather than the number of reps. Supposedly, this will give you bigger gains. For decades, people have been convinced that making every rep last longer means you’re getting more out of your workout. Sounds logical, right? Well, not entirely.

What is Time Under Tension (TUT)?

Definition: The duration your muscles are actively working during a set.
Assumption: The longer the tension, the more muscle growth.
Science says: It’s not about how long your muscles are under tension, it’s about taking the set close to failure.

Why It’s Debunked

Researchers like Brad Schoenfeld have looked into this, comparing various rep ranges, from just one rep to over 100 reps per set. Their conclusion? Whether you do 5 reps or 50, it’s all about taking the muscle to near failure. Hitting failure, rather than slowing down every rep to stretch out time under tension, is what truly stimulates growth.

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On top of that, a recent review on repetition tempo (how fast or slow you perform a rep) concluded that, although controlling the eccentric phase (lowering the weight) and being explosive on the concentric (lifting) might have some benefits, the overall time under tension doesn’t seem to matter much for muscle growth. A set duration of 20 to 70 seconds is recommended, which happens naturally if you’re working in the 5-50 rep range without trying to slow down each rep.

So, what should you focus on? Stick with a normal rep range (usually 5 to 20 reps) and work toward failure. Trying to intentionally slow down every single rep just overcomplicates things.

Key Takeaway: There’s no need to slow things down excessively. Use a reasonable rep range, focus on proper technique, and take each set close to failure. “You’ll never need to worry about time under tension ever again.”

2. Muscle Activation Through Electromyography (EMG)

Another popular technique still floating around the fitness world is using electromyography (EMG) readings to determine the best exercises for building muscle. You’ll see influencers or trainers sticking electrodes onto muscles to measure how much electrical activity occurs during certain exercises. The theory? The more muscle activation, the better the gains. This method has been around for a while, but here’s where it falls apart.

What is EMG?

Definition: A research technique that measures electrical activity in muscles during contraction.
Assumption: More activation means more growth.
Science says: Muscle activation doesn’t always correlate with muscle growth.

Why It’s Debunked

While it might sound like the future of personalized fitness, the assumptions behind EMG have been called into question by researchers. EMG measures neuromuscular excitation but doesn’t necessarily predict muscle growth. For instance, a study compared the muscle growth effects of squats and hip thrusts, even measuring EMG activity for both exercises. Despite the differences in muscle activation shown by EMG, the actual muscle growth didn’t align with those readings.

In short, just because an exercise shows higher EMG activity doesn’t mean it’s the best choice for hypertrophy. You can get caught up in shiny technology, but relying solely on EMG to pick your exercises might not give you the results you’re after.

Key Takeaway: Don’t base your exercise selection on EMG readings. Instead, choose exercises proven by research and experience to work for muscle growth—squats, deadlifts, presses, and rows—without worrying about how much the muscle “lights up” on a fancy machine.

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3. Body Part Splits

Body part splits are another classic gym strategy, popularized by bodybuilders for decades. The idea is to train one muscle group per day, typically on a 5-day rotation: chest day, back day, leg day, and so on. This approach has been a staple of bodybuilding routines, but modern research suggests there’s a better way to structure your training.

What is a Body Part Split?

Definition: Dividing your training week into days focused on individual muscle groups.
Assumption: Focusing on one muscle group per day maximizes growth.
Science says: Training each muscle more frequently leads to better gains.

Why It’s Debunked

Recent meta-analyses on training frequency suggest that hitting each muscle group at least twice per week is more effective for hypertrophy than training it just once, as body part splits do. When you train a muscle more frequently, you stimulate muscle protein synthesis (MPS) more often, leading to greater growth over time. Body part splits, which usually only hit each muscle once a week, just don’t stack up.

In fact, research has shown that muscles recover faster than we might think, and training them more frequently can lead to better results. If you can train 2-3 days a week, a full-body routine works best. If you can hit the gym 4-6 days, try an upper-lower split or push-pull-legs routine. These approaches allow you to train each muscle group at least twice a week, which is optimal for muscle growth.

Key Takeaway: If you’re still sticking with the old-school body part split, it’s time to upgrade. Aim to hit each muscle group twice a week with either full-body workouts or an upper-lower split.

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4. Resting Between Workouts

“Wait at least 48 hours before training the same muscle again.” You’ve probably heard this rule too. It’s often said that muscles need a full two days to recover between sessions, otherwise, you’ll overtrain or risk injury. But, like many old-school gym rules, this one doesn’t hold up under scrutiny.

What is the Rest Rule?

Definition: Resting 48 hours or more between working the same muscle group.
Assumption: Muscles need a full recovery period between workouts to grow.
Science says: Context matters—your muscles might not need that much rest.

Why It’s Debunked

While recovery is important, the old 48-hour rule is an oversimplification. For instance, if you do a light set of bicep curls today, would you really need two full days before doing another set? Probably not. Science has shown that the rest period needed between workouts depends on the intensity of your previous workout and your overall recovery (like sleep and nutrition).

Studies on training frequency found that training on consecutive days, even for the same muscle group, doesn’t necessarily hinder progress. In fact, training a muscle more often—even on back-to-back days—can still yield strength and growth benefits, provided you manage intensity and volume.

Key Takeaway: The amount of rest you need between workouts isn’t set in stone. If you feel recovered and your performance isn’t suffering, it’s okay to train a muscle more frequently, even on consecutive days.

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Final Thoughts

If you’ve been following these debunked strategies, don’t worry—you’re not alone. The fitness industry is full of myths and outdated practices. But as research evolves, so should our approach to training. By sticking to scientifically backed methods, you’ll not only simplify your workouts but also maximize your results. So forget about time under tension, throw out that EMG machine, ditch the body part split, and don’t stress over how much rest you’re getting. Just focus on lifting heavy, training frequently, and pushing yourself close to failure.

Your muscles will thank you!