Muscle, Strength & Survival

“The only reason the body adapts is because there’s a threat to its survival,” says Brad Schoenfeld, PhD, an exercise science professor at Lehman College.

From an evolutionary standpoint, your body doesn’t know the difference between a barbell and a boulder. When you lift something heavy or sprint up a hill, it treats it as a survival test—and adapts accordingly to handle future threats.

Schoenfeld, a former competitive bodybuilder, explains that strength training, like interval training, works because it’s intermittent but intense.

You can measure strength intensity in two ways:

• Intensity of load: The percentage of your one-rep max (1RM).
• Intensity of effort: How close you get to muscular failure in a set.

Even lifting light weights to failure (near-zero “reps in reserve” or RIR) can boost muscle growth—proving it’s not about the weight alone but how hard you work.

Intensity Isn’t Just for Lifters or Athletes

If you’re not chasing bigger biceps or new squat PRs, is intensity still worth it? Absolutely.

Most of the general health benefits—like better metabolic function, balance, mobility, and lower all-cause mortality—are linked to both aerobic and resistance training. But the best results come when you combine the two.

“Lifelong exercisers who only focus on one approach—either endurance or strength—aren’t fully optimized,” says Andy Galpin, PhD, of Parker University.

Galpin cites the case of identical twins: one a lifelong endurance athlete, the other sedentary. Despite the endurance athlete’s superior cardiovascular fitness, his sedentary brother actually had more muscle strength and size.

The takeaway? To thrive long-term, you need both. And intensity can help you get there faster—especially if you’re short on time.

You Don’t Need Much to Benefit

How little time are we talking?

• 11 minutes, 3x per week of bodyweight circuits improved cardiovascular fitness in inactive adults (2021 study).
• Just one high-intensity workout per week slashed mortality risk by up to 60% (2006 Norwegian study).
• “Weekend warriors” who trained 1–2 days/week reduced their risk of death by 30% (2017 study).

You can even try “exercise snacking”—a few 1-minute high-intensity bouts spaced throughout the day. It not only boosts fitness but helps break up long periods of sitting.

The Bottom Line: Intensity Pays Off

You don’t need to love intense exercise. You don’t need to do it for hours. You don’t even need a gym.

But if you’re willing to work hard for just a few focused minutes a day, your body will thank you—with more energy, better health, and possibly a longer life.

Because in the end, consistency matters more than anything. And for many people, quick and intense is the most realistic way to stay consistent.