Network Magazine Summer 2016 | Page 36

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? WORDS: DR MARK MCKEAN PhD here 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. T Aerobic activity 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 longduration moderate-intensity condition (15 minutes at 60 per cent VO2 max) 36 | NETWORK SUMMER 2016 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). Stretching 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.