At Discover Strength, we often refer to our approach to resistance exercises as HIT or High Intensity Training. We have used this terminology for the last 10 years and I have employed HIT as a strength coach since 1999. Recently, the terms "High Intensity Training," "HIT", or "HIIT" (High Intensity Interval Training) have increased in popularity. Seemingly, if your heart rate is elevated or if there is sweat dripping off your nose during exercise, you are performing a variation of "HIT." This really couldn't be any further from the truth.
The acronym HIT was developed in 1975 by Dr. Ellington Darden during a presentation he was giving at Duke University. He sought to articulate the research findings and approach to strength training popularized by Arthur Jones, the founder of Nautilus Sports Medical Industries. Since 1975, scores of excellent books have been written about HIT, strength and conditioning coaches in virtually every sport have employed HIT with a variety of athletes, and body-builders have utilized HIT in their training. Only in the last five years has the term "High Intensity Training" been used to describe a multitude of training approaches ranging from P90X, to sprint interval training, to Cross
Fit. The aforementioned approaches to exercise couldn't be any further from the original definition of HIT.
What is HIT? In it's original and purest form, HIT involves the following:
- Intensity. Each set is performed to the point of momentary muscle failure; the point in which another perfect repetition cannot be performed. The preponderance of research suggests that intensity and muscle failure trump all other exercise variables.
- Brief Workouts. Rather than spend 1-2 hours during a given workout, HIT advocates for performing only 5-12 exercises; a total of 20-40 minutes of time spent in the gym. The time-intensity continuum dictates that as the length of a workout increases, the intensity must decrease. You can train hard or you can train long, but you can't do both.
- Infrequent Training. Instead of hitting the gym 3-5 days per week, HIT advocates 1-2 weekly workouts. We don't get stronger and reap the benefits of strength training while we strength train, we reap these benefits as we recover from the training stimulus.
- Perfect Form. Slow, controlled movement speeds maximize muscle tension and decrease injury risk by minimizing the forces exposed to joints and connective tissue. If you are swinging the weight, incorporating momentum, or moving the weight rapidly, you are unloading your muscles while simultaneously increasing your injury risk.
- Progression. Gradually increase either the resistance or the number of reps performed as you become stronger.
- Utilize a combination of free-weights, machines, manual resistance, band resistance, and body weight. It's not the tool, but how the tool is used that is important.
Dr. Ken Leistner, a long-time HIT advocate describes HIT as:
"High-intensity training is going all-out, not almost all out. It is taking one set to one's absolute limit, not almost to the limit. It is using whatever equipment is available, not just a machine or group of machines. It is not the words of two or three men, but a commitment to work as hard as possible while in the gym without socializing, resting excessively between sets, or falling prey to the 'this isn't going to work so I'll copy the star' attitude."