Improve performance by 4% - do this one simple thing.

As an S&C coach I have been fortunate to learn from many great coaches and applied sports scientists who are at the cutting edge of innovation and integration.  As such I know of a few simple interventions that can assist in athletic performance. However I feel that these aren't implemented in the manner or frequency that they should be.  I am not talking about anything complex and in fact these concepts are relatively cheap, legal and more importantly they work. So over the next few blogs I will introduce these concepts to you.

With the Winter Olympics upon us, I felt that the first performance enhancement intervention that would be of relevance to this series of blogs is the role that muscle temperature plays in performance and how passive heat maintenance can assist with performance.

Firstly to understand why passive heat maintenance can a valuable tool it is important to highlight the importance of muscle temperature to performance. Muscle temperature (T_m) has demonstrated strong associations with power output, with an approximate 4% increase in lower body power output per 1°C increase in T_m (9, Figure 1).  Increases in T_m of approximately 3° to 4°C are required for an optimal warm-up effect (4,8).  An active warm-up consisting of moderate-intensity exercise (80–100% of lactate threshold) generally produces rapid increases in T_m within 3 to 5 minutes, which reaches a relative equilibrium after approximately 10 to 20 minutes of exercise (4,8).  Therefore, it is important for coaches to consider the timings, duration, intensity and content of the warm-up to maximize its effectiveness.

Figure 1. Relationship between muscle temperature and power output across a time period before and after a warm-up.

 One such method to help maintain core temperature (T_core) and T_m during the post warm up transition phase is through passive heat maintenance (PHM) (6,7).  Passive heat maintenance involves the use of an external heat source such as heated clothing, outdoor survival jackets, and heating pads, which can be applied to the desired muscle groups to maintain post-warm-up muscle temperature and, thus, the temperature-mediated pathways that will aid performance (6).  For example, in elite bob-skeleton athletes (3), a 65% greater tympanic (ear) temperature was reported when an active warm-up was performed with using an outdoor survival jacket in between warm-up activities and during the period until testing which was also associated with an improvement in 20m sled-sprinting performance, compared with a control condition (room temperature ~20°C).  In professional rugby league players, repeated sprint performance and vertical jump performance (peak power) were greater when applying a blizzard survival (full body length) jacket during a 15-minute post-warm-up recovery period than in a control condition (room temperature ~22°C) (6, Figure 2).

My own work in this area (unpublished data) investigated the impact of different clothing attire whilst sitting passively for up to 20 minutes.  In the first study (room temperature 15°C) three different clothing options were used; t-shirt and shorts (control), fleece blanket and jumper (Blanket_normal) and fleece blanket lined with a heat-reflective emergency thermal blanket and jumper (Blanket_reflective). At 10 minutes of sittings all three conditions showed similar decrements of approximately 1-2% in tympanic temperature. However at 20 minutes of sitting, there was a remarkable difference between all three conditions where the Blanket_reflective  (− 2.5%) was the best intervention followed by Blanket_normal (− 4.1%) and then the control intervention (− 6.8%).  I have also noted similar results at 18°C.  Of particular note was how the athletes subjectively felt better using a passive heat maintenance garment compared to wearing typical clothing (including wearing tracksuits at 18°C).

Incorporating PHM into your athletes’ competition (and training) regime is very affordable.  At the entry level, heat-reflective emergency thermal blankets are very accessible and cheap to purchase.  Another option is to use heavy-duty foil insulation as a product that can be sewn into blankets and clothing to provide a more innocuous solution for the athlete (Figure 3). It is also important to consider the weather conditions that your athletes are competing in to ascertain the right times to use PHM.  Even fluctuations between day and evening temperatures are another important consideration.  At the most basic level, even ensuring your athlete has appropriate clothing attire that is worn at the correct times is a simple and practical method to assist with their performance.

Figure 3. Thermal blankets and reflective insulation are practical and affordable ways to incorporate passive heat maintenance.

In summary, it is evident that increasing body temperature efficiently during the warm-up and maintaining body temperature during the post-warm-up transition phase is vital from subsequent competitive performance. However saying this, the challenge to the coach is applying this information into applied practice.   A basic checklist that could be considered when preparing an athlete’s pre-competition routine encompasses three main areas of warm-up, transition phase and competition (Figure 4).

Figure 4. Schematic overview of considerations for implementing passive heat maintenance.

Through systematic forward planning, logging of warm-up routines and transition phases in relation to performance outcome, a more stable physiological platform for optimal performance can be established.

Please note, that if you live in warmer climates this may not have relevance for you directly. In these types of environments maintaining a cooler core temperature is a consideration (i.e. warm muscles, cool core) but that is another blog all together. However saying that, recently we had our State Athletics Championships in Brisbane.  After coming off a few weeks of warm temperatures (30-35deg C) we had a few days of rain and the temperature during the evening dropped to around 18 degree C. Furthermore the athletics track typically gets quite cool in the evenings despite how hot the day was.  Consequently despite the warmer climate of Brisbane, this was a specific example of where PHM could have been implemented (and was by 2 athletes that I work with).

Therefore my challenge to you all is to look into your own practices and see how you can implement this simple intervention.

Next week - exciting news

Please keep an eye out for my blog next week.  I will be inviting a good friend and colleague, Craig Pickering (@craig100m) along to guest blog for me.  Not only is he an Olympian, he is a well respected sports scientist specialising in performance enhancement and a regular blog writer. So I am looking forward to sharing his thoughts on another simple intervention aimed at improving performance.

For more information, this article and references is  available for download in the resource section of my website.