June 17, 2019

Plyometrics and High-intensity Interval Training (HIIT): What’s the big deal?

Author: Dr. Erin Babineau

I often say to patients that strengthening can be whatever it means to them. This could be free weights, yoga based strength, machines, body weight strengthening (Calisthenics), all the way to a Cross Fit or organized strengthening class that involves High Intensity-interval training – otherwise known as HIIT workouts. My job as a physical therapist by the end of a patient’s care is to prep them to manage their bodies independently. This means that I help my patients decide what strength means to them and how they can efficiently integrate some sort of strengthening and body maintenance routine into their daily habits or work out. I strongly feel that this is patient specific and a team effort to decide what this looks like for a person. It can be corny, but I call it a person’s “body resilience plan” – a routine that keeps you out of my office and doing activities that you love.


Saying that, I frequently talk about HIIT workouts and plyometric exercise as a form of efficient exercise and therefore injury prevention to my patients. HIIT work-outs are defined as “a form of interval training, a cardiovascular exercise strategy alternating short periods of intense anaerobic exercise [60-80% of a person’s effort] with less intense recovery periods”. As most people know, they are super popular because they are efficient. There are tons of studies out there that show we can work out for shorter, more intense periods, and still get similar results to longer workouts. HIIT workouts and plyometrics have been used with athletes for a long period of time, but they can be easily added into anyone’s workout routine.

Davies, a renowned sports medicine physical therapist and professor at Georgia Southern University, states that “Plyometric training is often considered the missing link between strength and return to performance”. Further, he describes what plyometrics physiologically does in our bodies as it changes what types of muscle fibers we recruit: “Slow twitch (ST) fibers are typically recruited at submaximal intensity efforts [walking, biking, casual lifting], and then as the intensity increases, the fast twitch IIa fibers are recruited at approximately 30 percent up to about 80 percent of maximal intensity [effort]. At approximately 70‐80 percent intensity [effort], the fast twitch IIa, IIb fibers are then recruited. Thus, plyometrics need to be performed with high intensity efforts, above 80 percent, to recruit the fast twitch fibers that are crucial to power development”. When we exert higher level efforts during a workout, even for a shorter amount of time, we see that these type II muscle fibers are stressed in particular. These type II muscle fibers allow us to stay healthy and respond to events that involve quicker reaction times. For example, especially in MN, these fast twist muscle fibers are what help prevent us from injury when we need to respond quickly when we slip on ice. Our muscles now are equipped with adequate power and a speed component to react and recruit these type II muscle fibers that keep us injury free.  


Overall, adding some sort of speed component improves our neural efficiency by enhancing coordination of our nervous system and recruitment of these Type II muscle fibers. Plyometric training increases performance of our neuromuscular system by improving our reaction times if we simply have to move quickly – things we do on a daily basis that aren’t just specific to athletes.


Check in with your physical therapist to see how you can safely progress into some basic speed work. A lot of times this is something we often forget about, and at the same time keeps you out of my office, which is ultimately the end goal for all of my patients throughout the rehab process. Some basic plyometric work can help all of us active and continue to participate in the things we enjoy.




Davies et al. Current concepts of Plyometric Exercise. Int J Sports Phys Ther. 2015 Nov; 10(6): 760–786.


Gibala et al. High-intensity Interval Training: A Time-efficient Strategy for Health Promotion?. Current Sports Med Rep. 2007; 6 (4): 211–13.