Achieving peak performance/health is a balancing act. Among other things, it requires balancing mostly low-intensity training with a prudent amount of high-intensity efforts. This approach, usually called "polarized training", advocates for an 80/20 split between low (Zone 1 or 2) and high-intensity (Zone 4 or 5) efforts. It has emerged as a highly effective strategy for runners, cyclists, and others interested in maximizing their physiological adaptations.
Over the past few months, we have published an extensive discussion on the importance of low heart rate training, as well as our most recent posts on the importance of pushing harder every now and then. It is now time to get into the practical aspects of integrating high-intensity sessions into your regimen. We provide strategies, training tips, and some sample workouts to enhance performance without succumbing to overtraining or injury.
This is the first of a two-part series. In this part we explain polarized training, and in the next part we get specific with ideas and tips.
Understanding Polarized Training
Polarized training is a concept where roughly 80% of our runs/rides are low-intensity efforts (Zones 1 or 2), and 20% are high-intensity efforts (Zones 4 or 5). But that second number isn't somehow magical: the physiological adaptations that occur with high-intensity work often don't require much time. The idea, as the name suggests, is you want to focus on the poles of the intensity distribution and spend as little training time as possible in that middle area.
Fundamentally, the polarized model is built around two, paired ideas:
- Low-intensity training builds endurance, resilience, and aerobic capacity,
- High-intensity workouts are crucial for improving speed, strength, performance, and numerous advantageous physiological cardiovascular adaptations.
The key is to find a balance that maximizes benefits while minimizing risks. But the goal is, as ever, to get healthier as simply and straightforwardly as possible, and do it while keeping the likelihood of injury as low as possible.
Injury prevention and recovery
High-intensity training increases the risk of injury if not approached carefully. Focus on proper warm-up routines, incorporate strength training to build muscle resilience, and never underestimate the power of rest and recovery.
- You push
- You get tired
- You rest
- You adapt
Without a proper recovery... there is little adaptation.
Type 2 fibers and loss of muscle mass
Another often overlooked benefit of high-intensity training is its effects on type 2 or fast-twitch fibers. These type 2 fibers are recruited during high-intensity efforts in the gym or the trail. Most muscle atrophy or loss of muscle mass is due to the loss of these type 2 fibers. The loss of these fibers leads to issues such as sarcopenia but also causes us to lose our explosive potential. That makes everyday activities like going up a set of stairs challenging.
The role of high-intensity workouts
High-intensity training sessions are critical for pushing the body's aerobic and anaerobic limits. These workouts include interval training, hill repeats, and tempo runs, each designed to improve aspects like VO2 max and lactate threshold. For instance, Zone 4 workouts focus on sustained efforts at a hard pace (threshold run), while Zone 5 is about short, all-out bursts (sprints) that train your body to handle extreme intensities.
Cardiovascular Adaptations from High-Intensity Training
High-intensity training (HIT) has a role in enhancing cardiovascular fitness. This type of training induces various adaptations within the cardiovascular system, improving heart health, endurance, and athletic performance. Due to its role in improving VO2 max, exercise in the high-intensity domain also offers longevity benefits.
For our premium subscribers, we now go on to discuss many of the adaptations that take place. And then we discuss how you can think in broad strokes about planning to be more polarized.