Push Harder, Live Better: Why High-Intensity Training Needs To Be In Your Training

We all know exercise is good for us—but research shows that pushing harder through high intensity intervals offers benefits that go far beyond just getting in shape. These advantages touch every part of our lives: how long we live, how clearly we think, and even how resilient our bodies are to disease. That’s why it’s essential to incorporate high-intensity interval training (HIIT) into a balanced program. At Black Flag, we make this a priority, building VO₂ max–based work into our training to ensure our members experience the full spectrum of these benefits.

When scientists talk about “vigorous” activity, they mean exercise that pushes you beyond a comfortable conversation pace—where your body begins producing noticeable amounts of lactate, the byproduct of high-intensity efforts. Training here is key because it raises your lactate threshold—the point where lactate and hydrogen ions accumulate in muscle, impairing force production and making contractions harder to sustain. This is why performance drops so quickly during hard efforts. Sprinting, tough bike intervals, or barbell cycling all fit into this category. While moderate-intensity work is crucial for heart health and recovery, the magic happens when you combine it with structured high-intensity sessions.

 One of the most consistent findings in exercise science is the link between vigorous training and VO₂ max, the gold-standard measure of how efficiently your body uses oxygen. A higher VO₂ max—paired with strength and lean muscle—has been strongly associated with longer life expectancy and lower risk of chronic disease (Ross et al., Progress in Cardiovascular Diseases, 2016). Intervals performed at high intensity, whether through cardio, mixed-modal, or load-bearing work, have even been shown to improve cardiovascular structure and reverse age-related stiffness in the heart (Levinger et al., Journal of Applied Physiology, 2020).

 The brain benefits too. Lactate isn’t just a “burning” waste product—it’s an energy source and signaling molecule. High-intensity training triggers the release of brain-derived neurotrophic factor (BDNF), which supports learning, memory, and mood regulation (Dinoff et al., Neuroscience & Biobehavioral Reviews, 2017). This means regular exposure to intensity sharpens attention, boosts focus, and helps preserve brain health as we age (Ahlskog et al., Mayo Clinic Proceedings, 2011).

 Emerging evidence also links vigorous exercise to reduced cancer risk. Beyond bolstering immune function and lowering inflammation, intense blood flow during hard sessions may help the body eliminate circulating tumor cells (Hojman, Nature Reviews Endocrinology, 2017). On a cellular level, these workouts enhance glucose metabolism, stimulate mitochondrial growth, and improve the repair and removal of damaged cells—core mechanisms tied to slowing the aging process (Larsen et al., Journal of Physiology, 2012).

 Here’s the exciting part: improvements in cellular health, lactate clearance, and metabolic efficiency don’t just come from cardio. We can achieve them through high-intensity mixed-modality training and strength work, making the body more resilient at both a systemic and local level.

 The best news? You don’t need endless hours to see results. Well-researched protocols like the Norwegian 4×4—four intervals of about four minutes at high intensity with active recovery—are highly effective. But so are shorter and longer high-intensity pieces (Gibala & Little, Journal of Physiology, 2010). What matters most is consistency over time. Weeks and months of layering vigorous efforts into your training tilt the odds toward longer healthspan and sharper brain function.

Of course, intensity only works when paired with recovery which in turn drives adaptation (increased fitness). Balanced, gradual progression, and lower-intensity aerobic work are essential, whether you’re new to training or experienced. “Intensity” is relative—what’s tough for one person may be manageable for another—so progression based on individual fitness level, training age and lifestyle factors all matter in determining intensity of training.

The bottom line: if you want more than fitness—if you want to age well, think clearly, and protect against chronic disease—vigorous exercise is one of the most powerful tools at your disposal. It’s not about grinding yourself into the ground. It’s about giving your body and brain the signals they need to adapt, repair, and thrive through a balanced blend of strength, quality muscle building, and VO₂ max training.