High-Intensity Training: How Much Is Too Much?

Insanity and P90X are all the rage, and Tabata has infiltrated every gym across the country. Everywhere you turn, high-intensity interval training (HIIT) is being touted as the best way to get — and stay — in amazing shape. But at what cost? Turns out, going pedal to the metal in every workout can diminish returns on your training investment, increasing your risk of burnout, illness and injury.

Many recently published studies have proven the protocol can burn 15–20% more calories and increase endurance in a relatively short amount of workout time, which in our time-crunch society is appealing. And while high-intensity training itself isn’t harmful, overtraining can lead to inadequate or incomplete recovery, which at best can impede your training goals and at worst, can lead to injuries.

It’s not just newbies who are overdoing it. A lot of experienced exercisers are looking for the latest, greatest thing — a way to raise the bar — and end up thinking more high intensity training must be better. Not the case. According to experts, HIIT should be performed no more than three times per week for 20–30 minutes max. If you’re pushing hard, muscles fatigue quickly, and eventually quality of movement is compromised.

Your body doesn’t get stronger or leaner while you’re working out; allowing your body to recover, and getting enough rest allows your body to repair damaged muscle fibers and restore glycogen stores and hormone levels. Giving your body a break is essential.

You can safely include HIIT in your weekly training, just make sure to follow these guidelines:

• Have a solid fitness baseline before engaging in any type of HIIT program.
• Employ proper rest periods between sets. If your heart rate doesn’t come down between sets, you’re not doing a true interval.
• Maintain good form the entire workout.
• Balance your exercise program with lower intensity training.