Muscle tightness results from an increase in tension for various reasons. Passively, muscles can become shortened through postural adaptation such as reduced hip flexor length from prolonged sitting, scarring from injury such as muscle tears or post surgery. Actively, muscles can become shorter due to spasm, weakness or overuse. Regardless of the cause, tightness limits range of motion and may create a muscle imbalance increasing the susceptibility to injury. 1
Stretching exercises have traditionally been included as part of an athlete’s training and recovery program. Evidence shows that physical performance in terms of maximal strength, number of repetitions and total volume are all affected differently by the each form of stretching – static stretch (SS), dynamic stretch (DS) and Proprioceptive Neuromuscular Facilitation stretching (PNFS). 2
SS involves lengthening a muscle until either a stretch sensation or the point of slight discomfort is reached. The muscle is then held in a lengthened position for a prescribed period of time: generally greater than 60 seconds. SS is commonly used in clinical and athletic environments with the specific aims of increasing joint range of motion (ROM) and reducing risk of injury by maintaining length post activity as part of a cool down regime. 3
DS involves the performance of a controlled movement through the available ROM. For a number of reasons, DS is sometimes considered preferable to SS in the preparation for physical activity. 3
- There may be a close similarity between the stretching and exercise movement patterns such as high knees, leg swings or bottom kicks in preparation for running. 3
- DS activities can elevate core temperature, which can increase nerve conduction velocity, muscle compliance and enzymatic cycling, accelerating energy production. 3
- DS and dynamic activities tend to increase rather than decrease central drive, as may occur with prolonged SS 3
Proprioceptive Neuromuscular Facilitation Stretching
PNFS is a stretching technique used to improve muscle elasticity and has been shown to have a positive effect on active and passive ROM. Four theoretical mechanisms were identified: autogenic inhibition, reciprocal inhibition, stress relaxation, and the gate control theory. 4 Basically, instead of just passively stretching the target muscle for example the Quadriceps, the person contracts the antagonist muscle (Hamstring) or the agonist/target muscle in this case the Quadriceps. 4 The client contracts the muscle being used during the technique at 50 to 75% of maximal contraction, for three sets of 8-10 seconds, and then relaxing moving further into the new available range. Resistance can be provided by a partner, therapist or with an elastic band or strap.
Stretching, Strength and Total Volume – A Clinical Study
Twelve strength-trained men completed 8 experimental sessions testing the effect of SS, DS, PNF, or NS on maximal strength in the leg press (1 repetition maximum) and total volume (number of repetitions performed at 80% 1RM). All of the stretching protocols significantly improved the ROM in the sit-and-reach test when compared with NS.
When compared with NS all the stretching protocols significantly reduced:
- The number of repetitions (SS: 20.8%, p < 0.001; BS: 17.8%, p = 0.01; PNF: 22.7%, p < 0.001)
- Total volume (SS: 20.4%, p < 0.001; BS: 17.9%, p = 0.01; PNF: 22.4%, p < 0.001).
- However, Leg press 1RM values were decreased only after the PNF condition (5.5%, p < 0.001).
The results from this study suggest that, to avoid a decrease in both the number of repetitions and total volume, stretching exercises should not be performed before a resistance training session. 2
Stretching and Explosive Force Disciplines – A Clinical Study
One hundred voluntary male athletes participated in this study. Vertical jump performance was evaluated by countermovement jump (CMJ). Participants were divided into 3 groups according to their flexibility and pre-jump performances after warm-up. For each individual group and the whole group, after all treatments, differences in CMJ values were obtained (p ≤ 0.05).
- DS increased the vertical jump in the groups with low and average flexibility, poor pre-jumping performance, and also in the whole group (p ≤ 0.05).
- PNFS + SS decreased vertical jump in groups of participants with high flexibility, moderate, and high pre-jumping performance and in whole group (p ≤ 0.05).
Therefore it seems that DS for athletes that rely on explosive power is the most appropriate protocol as a part of warm-up period. 5
Take Home Messages
- To increase ROM, all types of stretching are effective, although PNF-type stretching may be more effective for immediate gains. 1
- Dynamic stretching is recommended for warm-up for athletes before competition or activity. As static stretching will likely decrease strength and may effect performance. 1
- Post exercise static stretching is recommended for reducing muscle injuries and increasing joint ROM. 3 Although Stretching has not been shown to be effective at reducing the incidence of overall injuries. 1
- Stretching is often included in Physiotherapy interventions for management of many kinds of clinical injuries. Despite positive outcomes, it is difficult to isolate the effectiveness of the stretching component of the total treatment plan because the protocols usually include strengthening and other interventions in addition to stretching. 1
– LOULOU NEGOESCU
Loulou is one of the Physiotherapists at 4Lane Dunsborough.
- Page P. Current concepts in muscle stretching for exercise and rehabilitation. Int J Sports Phys Ther. 2012; 7(1):109-19. Available from: http://www.ncbi.nlm.nih.gov/pubmed/22319684.
- Barroso R, Tricoli V, Santos Gil SD, Ugrinowitsch C, Roschel H. Maximal strength, number of repetitions, and total volume are differently affected by static-, ballistic-, and proprioceptive neuromuscular facilitation stretching. J Strength Cond Res. 2012; 26(9):2432-7. DOI:10.1519/JSC.0b013e31823f2b4d.
- Behm DG, Blazevich AJ, Kay AD, McHugh M. Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Appl Physiol Nutr Metab. 2016; 41(1):1-11. DOI:10.1139/apnm-2015-0235.
- Hindle KB, Whitcomb TJ, Briggs WO, Hong J. Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function. J Hum Kinet. 2012; 31:105-13. DOI:10.2478/v10078-012-0011-y.
- Kirmizigil B, Ozcaldiran B, Colakoglu M. Effects of three different stretching techniques on vertical jumping performance. J Strength Cond Res. 2014; 28(5):1263-71. DOI:10.1519/JSC.0000000000000268.