By Musculoskeletal Physiotherapist |
Proprioceptive Neuromuscular Facilitation stretching, or PNF, is an extremely effective stretching technique designed to rapidly increase the length of sarcomeres within targeted muscles.
Although the name makes the technique sound complicated, it is relatively easy to put into practice and can bring about significant benefits in both rehabilitative and competitive settings.
What is PNF Stretching?
Muscles are plastic by nature, meaning that they can change length and size dependent on the demands placed upon them. A muscle that is repeatedly pumped without any real stretching can become chronically shortened, leading to a feeling of tightness and increased likelihood of being pulled during rapid movements. Think: hamstring injuries and footballers.
However, adding in just several minutes of PNF stretching each week for muscle groups susceptible to tightness can reduce this side effect of hard training and allow suppleness to be maintained whilst also reducing the risk of future injuries.
There is also evidence to show that, if performed after exercise, PNF stretching has the potential to increase power output and athletic performance (Bradley et al., 2007; Marek et al., 2005; Mikolajec et al., 2012), and this benefit can be maintained with just 2 sets of PNF stretching each week.
How Does PNF Stretching Work?
There are several proposed mechanisms as to how PNF stretching helps to increase flexibility. One of these is termed autogenic inhibition, and this is the process by which a prolonged muscular contraction in the PNF technique causes inhibition to the excitability of the nerves supplying the target muscle, which causes the target muscle to relax and allow a greater stretch (Hindle et al., 2012).
It is also worth noting that although there are some claims in the literature suggesting that stretching pre-exercise slightly decreases power output (Marek et al., 2005), the reported power deficits returned to normal levels 15 minutes after stretching (Bradley et al., 2007) and there has been shown to be absolutely no long-term decrease in strength from this stretching technique (Yuktasir et al., 2009). So in summary, avoid this stretching technique 15 minutes prior to exercise or an athletic event but otherwise, you’re good to go!
PNF Stretching Exercises
For this article, I will describe one type of PNF stretching (called contract-relax PNF) for 4 muscle groups that I find are often tight in the athletic population. These muscle groups are the hamstrings, quadriceps, calves and pectorals.
You’ll need a partner for this one!
Lie on your back on a bench or bed and have your partner raise the leg to be stretched upon their shoulder. Make sure the knee remains locked straight. Have your partner slowly lift the leg up to the point where you feel tightness in the hamstrings. Hold this position for 20-seconds to allow your muscles to relax into the stretch.
✓ Then, with around 50% of your maximum effort, press your leg down into your partners shoulder. They are to keep the leg in a static position while you press down for 7 seconds.
✓ At the end of the 7 second contraction, relax your leg, take a deep breath, and allow your partner to (gently!) increase the stretch on your leg by a few centimetres.
✓ Hold this new position for 20 seconds, then repeat the process up to 4 times.
Lay on your front with a pillow under the knee of the leg to be stretched. Pulling on a towel around your ankle to help increase the stretch, bend your knee as far as you can. When you feel the stretch on the front of your thigh, hold this position for 20 seconds.
✓ Then, at 50% of your effort, attempt to straighten your leg for 7 seconds. Make sure your leg doesn’t change position by resisting the motion by pulling the towel.
✓ At the end of 7 seconds, relax, take a deep breath, and increase the stretch. Hold this new position for 20 seconds, and repeat up to 4 times.
You can perform this one either with a partner or by using a strong towel or belt.
Remember there is a lot of power in your calf so if you’re using a partner make sure they brace themselves.
You can perform this action either with the knee straight (emphasis on gastrocnemius) or with the knee slightly bent (emphasis on soleus).
✓ Sit with your knee in the chosen position.
Option if you can’t reach your toes: Wrap a towel around your forefoot and pull back as if you were trying to pull your toes up towards you. When you feel a stretch in the calf, hold for 20 seconds.
✓ Then, at 50% of your max effort, push against the towel with your foot and hold for 7 seconds. At the end of the 7 seconds, relax, and increase the stretch.
✓ Hold this new position for 20 seconds, then repeat up to 4 times.
You’ll need a partner for this one too!
✓ Sit upright on a bench and clasp your fingers behind your head. Have your partner stand close behind you and pull your elbows back by locking their elbows over yours as shown in the picture. Hold this stretch for 20 seconds.
✓ Then, at 50% of your effort, contract as if you were trying to bring your elbows together and hold for 7 seconds. At the end of the 7 seconds, relax, take a deep breath, and breathe out as your partner increases the stretch.
✓ Hold this new position for 20 seconds and then repeat up to 4 times.
Take Home Message
So that’s a basic idea as to how to perform one kind of PNF stretching on several muscle groups that are commonly tight in the training population.
With these basic principles and a bit of creativity, this method can be applied to just about any muscle group in the body. Now go and stretch yourself!