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.
CURRENT CONCEPTS OF PLYOMETRIC EXERCISE – NOTES for blog post
“Plyometric training is often considered the missing link between strength and return to performance.”
The eccentric pre‐stretch phase has also been described as the readiness, pre‐loading, pre‐setting, preparatory, facilitatory, readiness, potentiation, counter‐force, or counter‐movement phase.
Amortization Phase (Time to Rebound)
The amortization phase is the time delay between overcoming the negative work of the eccentric pre‐stretch to generating the force production and accelerating the muscle contraction and the elastic recoil in the direction of the plyometric movement pattern.
Concentric Shortening Phase
The concentric phase can also be referred to as the resultant power production performance phase. This phase has also been described as the facilitated or enhancement phase of plyometrics
BASEBALL: For example, overhead throwing produces angular velocities that exceed 5000‐7000 degrees per second
KICKING, RUNNING, HOPPING: The angular velocities of the knee have been recorded at around 1,000 degrees/second
PHYSIOLOGIC GOAL: “The plyometric movement uses the pre‐stretch of the muscle‐tendon unit physiological length‐tension curve in order to enhance the ability of the muscle fibers to generate more tension and resultant force production. Biomechanically “priming” the muscle is supported by the work of Elftman.”
***The Elftman proposal simply states that the force production of muscle is arranged in a predictable hierarchy. This orderly format is that eccentric muscle contractions create the most force, followed by isometric contractions and then concentric contractions. Concentric muscle contractions therefore, are actually the weakest of the three modes of muscle actions. However, plyometrics create the greatest forces during the concentric power production phase. It is for this reason that the eccentric pre‐stretch and the short amortization phases are so critical for the optimum power development in a muscle.
DOMS: how do we educate and how do we avoid? It is critical to explain to the athlete that DOMS is a self‐limiting conditioning and usually resolves in approximately 7‐10 days. If the participant is a highly trained athlete, due to a repeated bout effect, they will not usually experience a DOMS response
REVIEW OF RECRUITMENT:
Slow twitch (ST) fibers are typically recruited at submaximal intensity efforts, and then as the intensity increases, the fast twitch (FT) IIa fibers are recruited at approximately 30 percent up to about 80 percent of maximal intensity. At approximately 70‐80 percent intensity, 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.
How are people gauging this? I use RPE – 60-80% fatigued. Should we have these signs in clinic?
There are generally three ways to recruit FT fibers:
1) maximum intensity effort,
2) electrical stimulation, and
3) fast movement patterns like plyometric exercises.
Explosive plyometric exercises may improve the neural efficiency through enhancement of neuromuscular coordination. Therefore, plyometric training increases neuromuscular performance by increasing the set speed in which the muscles may act. Ultimately this mechanism results in the enhancement of the neurologic system to allow neuromuscular coordination to become more automatic
SO WHO ARE WE APPLYING THIS TO?
Davies and Matheson indicate clinicians should make the training specific to the individual goals of each patient.
- Patient goals:
- Ex: gardening?
- Are they doing deadlift position?
- Ex: gardening?
- Falls risk prevention
- Drop squats
- Patient goals:
- Sport specific
- Education component to the athlete on pounds of force to get buy in
- The plyometric program should use the principles of progression and overload. This can be accomplished by manipulating the volume dosage (reps, sets, weight, etc.) of many different variables. The quality of the work is more important with plyometrics than the quantity of the work. In order to recruit the fast twitch fibers, the intensity of the work should be performed at high levels of intensity 80‐100% maximum volitional contraction (MVC)
- Additionally the rate of the muscle stretch is more important than the length of the stretch.
- We work manually and then are we loading into this tissue to reinforce?
- 48‐72 hours between sessions
- In the case of plyometric training, volume is often measured by calculating the load, counting the number of repetitions, sets, etc. of the specific activity (number of throws, jumps, etc.)
- Patients or subjects that need explosive powerful movements for their recreational or competitive athletic activities really need to train using plyometric exercises.
- Before initiating a plyometric exercise program, there should be a systematic functional testing algorithm developed to screen the subject or patient for the ability to participate with LE plyometrics