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Dynamic flexibility

Dynamic flexibility

Static stretching is out. Nick Grantham examines the case for the new pretender

Flexibility components are often included in training programmes as a key aspect of preparation for physical activity, with the goals of decreased injury risk and improved performance (1, 2) . Exercises and drills to improve flexibility have traditionally been classified as either static or ballistic (see Table 1, overleaf).

Ballistic stretching, with its focus on end-of-range movement, has long been the black sheep of the flexibility family. This stretch technique uses momentum to get the body or limb to forcibly increase its range of movement, an approach that can cause soreness and injury. Critics also say that ballistic stretching fails to provide adequate time for tissue adaptation to the stretch, and that it increases muscular tension, which makes it more difficult to stretch connective tissue.

By contrast, the inclusion of static stretching within warm-ups or training programmes has long been accepted without any scientific proof of its effectiveness. Of late, however, it seems that static stretching has also fallen out of favour, with critics arguing that it does not prepare the body for the movements employed later in training or in sports performance (3) .

Much of this recent backlash can be attributed to a growing body of research suggesting that static stretching has a detrimental effect on the subsequent performance of speed, power and strength work (4) . Studies have shown that static stretching can negatively affect the performance of a skill that demands high power outputs such as sprinting and jumping, even when preceded by a dynamic warm-up protocol (4) . While the underlying mechanisms for this adverse effect are still not fully understood, the negative effects reported in the literature have left coaches and athletes looking for an alternative. So, new ‘dynamic stretching’ protocols have been gaining a lot of attention (see summary box, opposite) as an apparently effective alternative way to enhance athletic performance, provide a safe warm-up and prevent injury (5, 6,7, 8, 9) .

Haven’t we been here before?

If you spend long enough working in the sports, exercise or rehabilitation industries, you will start to realise that everything is cyclical. Training techniques that you used 10 years ago will reappear under a new name to become the latest performance-boosting or rehab sensation. That, I believe, is what is happening with the current trend favouring dynamic flexibility work.

It seems to me that dynamic stretching is nothing more or less than a more ‘friendly’ version of ballistic stretching: it requires muscles to be moved through a range into some tension and then back out again. The main difference is that with dynamic flexibility, actions are supposedly controlled through a full range of movement, unlike the emphasis on small movements at the end of range used in ballistic work. Dynamic stretching can be performed slowly or quickly; actively (as in swinging an arm or leg under its own control); or passively, by someone else (10) . Research has demonstrated that both ballistic and dynamic stretching enhance flexibility; however, dynamic stretching develops optimum dynamic flexibility, essential for all sports.

Why are we only just starting to appreciate the benefits of dynamic stretching? In 1990 Zachazewski recommended a ‘progressive velocity flexibility programme’ (PVFP). This programme involved a series of dynamic (ballistic) stretches preceded by a warm-up. The speed and range of lengthening was combined and controlled on a progressive basis (3, 11) , as follows:

‘The athlete progresses from an environment of control to activity simulation, from slow-velocity methodical activity to high-velocity functional activity.

* After static-stretching, slow short end range (SSER) ballistic stretching is initiated.

* The athlete then progresses to slow full range stretching (SFR), fast short end range (FSER) and fast full range (FFR) stretching.

* Control and range are the responsibility of the athlete. No outside force is exerted by anyone else.’

While no controlled clinical studies or research have been published on PVFP, the principle of progressively moving from static to a more dynamic programme of stretching seems sensible.

Dynamic stretching in rehab

While the literature would seem to support the benefits of dynamic flexibility warm-ups over static stretching in performance terms, at the moment there is no comparable evidence base for its use in rehab or for longer term flexibility gains.

But, backed by research or not, the good practitioner will always consider the requirements of each individual when deciding on the most appropriate rehab tools. As a coach working with athletes and clients every day of the week, I’m amazed that people still seem to think there is a single right or wrong way to stretch. The right way will always be the approach that works best to meet the specific client and their rehab goals. You can’t fix everything with a hammer: sometimes you need to use a screwdriver.

Both methods of stretching have their place. Dynamic stretches may well be more appropriate for a warm-up. Static stretches, on the other hand, may be more appropriate at the end of a workout to help relax the muscles and facilitate an improvement over time in maximum range of motion (12) (ie, developmental stretching).

Whilst evidence increasingly suggests that static stretching may indeed adversely affect subsequent powerand strengthbased activities such as maximal lifts, sprinting and jumping (4) , this effect may be limited simply by reducing the length of hold for each static stretch (ie, 10 to 20 seconds is fine; it is from 30 seconds and longer that you are going to experience a drop in performance) (13) .

It will not surprise you to learn that I like to take an approach that combines these different techniques to suit the circumstances. If a client is found to have poor hamstring flexibility and this is a limiting factor for their training, my main focus will be on developing the hamstring range of movement. To improve ROM we will include a greater proportion of static stretches, we will probably even prescribe specific stretching sessions. We will then follow with some dynamic movements to prepare the body for sporting or training activity. If the client doesn’t present any limiting flexibility issues, we will skip the static stretches and simply include a range of dynamic stretches in preparation for the subsequent training session.

[077-TABLE1]

Warm-up moves

Here are my top five dynamic stretches that can be used as part of a typical dynamic warm-up (adapted from Boyle, 2004) (14) .

High knee walk

A great way to start the warm-up, it hits all the key muscles of the posterior chain (most importantly, the glutes):

* Step forward and grasp the shin of the opposite leg, pulling the knee in towards the chest.

* Concentrate on extending the stepping leg to get up onto the toes. This takes the body through triple extension (ankle, knee, hip), which is important for all running and jumping sports.

* Progress this movement into a high knee skip and then a high knee run.

Straight-leg deadlift walk

Gives a great active hamstring stretch plus a proprioceptive and balance workout:

* Reach both arms out to the side while attempting to lift one leg straight back and up to waist height.

* The stretch is felt through the hamstrings of the supporting leg, simultaneously activating the hamstrings of the moving leg, which will be working as a hip extensor.

[077-DYNAMICSTRETCHING]

Forward lunge walks

Works the anterior hip and warms up all of the leg and hip extensors. A tough drill which should only be included once the client has completed at least one week of single-leg strength work:

* Use a basic lunge pattern incorporating a step forward after each lunge (walking lunge).

* For an extra challenge, do the stepping lunges backwards.

Caterpillars

A total body warm-up drill. Tough but well worth the effort:

* Begin in a push up position.

* Drop the hips to stretch the abdominal area and then walk feet up as close as possible to the hands, keeping the legs straight (take baby steps and keep legs straight).

* Walk forward to take the hands away from the stationary feet, finishing again with the hips down to stretch the abdominals. This portion of the drill works the upper body, particularly the scapulothoracic region. Stationary spiderman

A great warm-up drill for any sport requiring lateral movement:

* Start in a push up position and step the right foot forward to just outside the right hand.

* Drop the right elbow to the ground.

* Return the foot to its original position and switch sides.

* Remember this is a dynamic stretch, so it should move from right to left leg in a rhythmical manner with no holds at the end position.

References

1. Bazett-Jones DM, Gibson MH, McBride, JM. ‘Sprint and vertical jump performances are not affected by six weeks of static hamstring stretching’. Journal of Strength and Conditioning Research 2008 ; 22 (1): 25-31.

2. Little T, Williams A. ‘Effects of differential stretching protocols during warm-ups on high speed motor capacities in professional soccer players’. Journal of Strength and Conditioning Research. 2006; 20 (1) 203-207.

3. Atler MJ. ‘Science of Flexibility’. Human Kinetics 2004.

4. Winchester JB, Nelson AG et al. ‘Static stretching impairs sprint performance in collegiate track and field athletes’. Journal of Strength and Conditioning Research. 2008; 22 (1): 13-18.

5. Burkett LN, Phillips WT, Ziuratis J. ‘The best warm-up for the vertical jump in college-age athletic men’. Journal of Strength and Conditioning Research. 2005 ; 19: 673-676.

6. Fletcher IM, Jones B. ‘The effect of different warm-up stretch protocols on 20m sprint performance in trained rugby union players’. Journal of Strength and Conditioning Research. 2004; 18: 885-888.

7. Stewart D, Macalus A and De Vito G. ‘The effect of an active warm-up on surface EMG and muscle performance in healthy humans’. European Journal of Applied Physiology. 2003; 89: 509-513.

8. Trimble MH and Harp SS. ‘Postexercise potentiation of the H-reflex in humans’. Medicine and Science in Sports and Exercise. 1988; 30: 933-941.

9. Young WB, Behm DG. ‘Effects of running, static stretching and practice jumps on explosive force production and jumping performance’. Journal of Sports Medicine and Physical Fitness. 2003; 43: 21-27.

10. Castella R, Clews W. Smart Sport: The Ultimate Reference Manual For Sports People. 1996; RWM Publishing.

11. Zachazewski JE. ‘Flexibility for sports’. In Sports Physical Therapy ed B Sanders, 201-238 . 1990 ; Norwalk CT. Appleton and Lange.

12. McNair, PJ, Dombroski, EW et al. ‘Stretching at the ankle joint: viscoelastic responses to holds and continuous passive motion’. Medicine and Science in Sport and Exercise. 2000; 33 (3): 354-358.

13. Siatras, TA, Mittas, VP et al. ‘The duration of the inhibitory effects of static stretching on quadriceps peak torque production’. Journal of Strength and Conditioning Research. 2008; 22 (1): 40-46.

14. Boyle M. Linear and Lateral Warm-up. In Functional Training For Sports. 29-53 2004; Champaign Il, Human Kinetics.

15. Yamaguchi T, Ishi, K et al. ‘Acute effects of dynamic stretching exercise on power output during concentric dynamic constant external resistance leg extension’. Journal of Strength and Conditioning Research. 2007; 21(4): 1238-1244.

16. Yamaguchi T, Ishi K. ‘Effects of static stretching for 30 seconds and dynamic stretching on leg extension power’. Journal of Strength and Conditioning Research. 2005 , 19(3): 677-683. Lange.

17. McMillian DJ, Moore, et al. ‘Dynamic vs. Static stretching warm-up: the effect on power and agility performance’. Journal of Strength and Conditioning Research. 2006; 20 (3):492-499.
 

Dynamic flexibility