EVIDENCE-BASED PRACTICE: Warm up methods and protocols
The benefits or otherwise of warming up before physical activity are much debated. So what does the science say is the best way to prepare clients for sessions?
There is ongoing discussion around the value and type of warm up suited to different types of training activity. The typical aerobic activity warm up has been the mainstay of this process for years, but has recently been considered less effective than previously thought. As training activities continue to evolve, so too have the warm ups associated with them. While it has always been accepted as best practice, the warm up must be progressive and develop the intensity and movements to create a change in the human physiology that prepares it for the actual training to follow.
Over the past ten years a more diverse approach to warming up has developed across the multiple training environments, but is often based on opinion rather than evidence.
Warming up via aerobic activity for a stretching session appears to have little or no value, with several studies showing a warm up did not increase effectiveness of static stretching and range of motion (ROM) (de Weijer 2003). Long-duration low-intensity (15 minutes at 40 per cent VO2 max) general warm up improved 1RM performance in strength-trained individuals by 3 per cent, but the long-duration moderate-intensity condition (15 minutes at 60 per cent VO2 max) reduced 1RM values on average by 4 per cent (Barosso et al. 2013).
An aerobic warm up has been shown to improve performance by reducing the anaerobic contribution to sprint cycling max performance (Wittekind et al. 2012). Similarly, a warm up of lower intensity and shorter duration was shown to elicit less physiological strain and produce higher power in initial stages of max rowing trial (Mujika et al. 2012).
The current evidence surrounding stretching pre or post-exercise is that it does not provide any reduction in muscle soreness or injury occurrence. Herbert and Gabriel in a systematic review (2006) question the value and quality of most research in this field, and most research has focused solely on the acute stretching protocols rather than the chronic effect of stretching and its value on injury prevention. Thacker et al. (2004) also concluded that there was not sufficient evidence in the current literature to endorse or continue routine stretching before or after exercise to prevent injury. Another systematic review by Small et al. (2008) clouds the issue further by concluding there was ‘moderate to strong evidence that routine application of static stretching does not reduce overall injury rates’ and yet there was ‘preliminary evidence, that static stretching may reduce musculotendinous injuries’. Several individual studies suggest aerobic warm up may assist in improving flexibility, for example, static stretching has been shown to be the most effective type of stretching to improve hamstring flexibility (O’Sullivan et al. 2009).
Many studies have also compared the types of stretching and the effect they have on performance. Samson et al. (2012) found no difference between the effects of static and dynamic stretching on sprint or countermovement jump height. A review by Kay et al. (2012) showed that a short-duration acute static stretch held for less than 30 seconds had no detrimental effect on maximal strength, but that stretches held for more than 60 seconds may affect eccentric strength. This has been supported by other research showing short-duration static stretching warm up has also had no effect on power outcomes (Ackermann et al. 2015). Finally, a review by Kallerud (2013) on static stretching reported detrimental effect on stretch shortening cycle performance, whereas dynamic stretching showed no negative effects. All effects were very low and the value or differences between outcomes were small.
Myofascial release techniques
One of the newer warm up techniques to become popular is the use of foam rollers and trigger balls for myofascial release. A broad body of research has provided good evidence to support the use of these tools. A warm up routine consisting of both a dynamic warm up and a self-myofascial release, total-body foam rolling session resulted in overall improvements in athletic performance testing (Peacock et al. 2014). Foam rolling, while found to reduce quadriceps DOMS, was also associated with reduced outcomes in performance tests related to speed, power, T-Test, and dynamic strength endurance (Pearcey et al. 2015). A foam roller used on the hamstrings was shown to increase sit and reach ROM (4.3 per cent) within five to ten seconds without any additional performance impairments (Sullivan et al. 2013). But, as always, there is conflicting evidence, as shown by Evans (2014) which found self-myofascial release to be no more effective than passive rest in increasing ROM or isokinetic force production of the hamstring muscle group. But, generally, most research is showing myofascial release appears to have a range of potentially valuable effects for both athletes and the general population, including increased flexibility and enhanced recovery (Beardsley 2015).
Neuromuscular training programs have been promoted as a more ideal warm up because they improve joint position sense, enhance joint stability and develop protective joint reflexes, ultimately preventing lower limb injuries. Neuromuscular training activities used as a warm up may include stretching, bodyweight strengthening, plyometrics or jumping drills, core stability, agility drills, and balance activities.
A systematic review by Hübscher et al. (2010) on neuromuscular training programs for sports injury prevention indicated that multi-intervention programs may reduce lower limb, acute knee and ankle injuries. The follow on review by Herman et al. (2012) supported the value of these types of activities prior to sports-specific training and agreed that they may reduce risk of lower limb injuries if completed for a period of at least three months.
High-load movement-specific dynamic warm ups have been shown to enhance power and strength performance. For example, warm up swings with a standard weight baseball bat are most effective for enhancing bat speed (Ackermann et al. 2015) and ballistic exercises may enhance performance in jumps and sprints (Maloney et al. 2014).
Overall value of warming up
Fradkin et al. (2010) performed a systematic review on the effects of warming up on physical performance. The majority of the 92 different warm up combinations (79 per cent) in the review showed that performance was improved after a warm up, 3 per cent showed no change and 17 per cent found warming up had a detrimental effect on performance. While the style of warm ups varied, from aerobic activity and stretching to strength exercises and circuits, the review also noted that where performance was negatively influenced, 64 per cent of the warm ups weren’t suited to the actual training activity, weren’t specific enough to the activity in question, or weren’t of long enough duration to change muscle temperature. The review concluded that there is still value in warming up, but that the warm up should focus on the body segments that will be used in the subsequent performance and should not be so intense in nature as to fatigue the participant.
Current evidence shows that warm ups may impact on the effectiveness of the training session conducted. It has also shown that there is not really a single warm up style that suits all activities. As a trainer your goal should be to develop a warm up routine that is not only specific to your proposed activity, but relevant to the individual client, while still managing any time restraints. Significantly greater research is required to assess the specifics of the varied styles of warm ups and their value to the desired training outcomes. What we can say for certain is that the traditional model of a five-minute cardio warm up and static stretch may not be ideal, and there are certainly better options available that will be of greater value to your clients.
Dr Mark McKean PhD AEP CSCS is a sport and exercise scientist and Level 3 Master Coach with ASCA. He is Adjunct Senior Research Fellow at USC and editor in chief for Journal of Fitness Research.