Improving Exercise Performance in the Heat

Dr Caroline Sunderland's unique research has challenged and changed both academic thinking and real-world practices relating to heat acclimation and performing in hot environments.

This research has made, and is making, a significant impact across the world, improving both physical and cognitive performance across a range of sports from elite to recreational level. Examples include:

• a fitness training manual that is now used by all international hockey umpires
• acclimation and cooling strategies for international hockey players
• acclimation strategies for international athletes, international netball players and recreational and charity runners.

Heat acclimation

Dr Sunderland's research has changed international protocols and practices and so improved the performance of a wide range of sportsmen and women, from international hockey players and elite athletes, to school teams and individuals engaged in charity events.

The Great Britain hockey team has used Dr Sunderland’s acclimation process and sought her advice. The head coach of the British squad commented: "We have chosen to use Nottingham Trent for our acclimatisation training because of Dr Sunderland's expertise coupled with the unparalleled facilities. Such preparation can mean the difference between winning and losing."

Members of the England and Wales hockey squads also came to NTU to be acclimatised by Dr Sunderland prior to the Commonwealth Games in Delhi in 2010.

Neck cooling to enhance performance

Dr Sunderland was the first to demonstrate that neck cooling improves performance. Her work attracted worldwide attention from both researchers and the media. The field hockey coach at Indiana University highlights the value and impact of her work: "Our pre-season is exceptionally hot. By following Dr Sunderland's very specific recommendations regarding neck cooling and the timing of technique / skill and acclimation sessions, we were able to safely and efficiently make the greatest performance gains ever for the coming season."

Improving hockey performance

Dr Sunderland's research changed and continues to influence the performance of international hockey players and umpires during competitions in hot climates, such as the Beijing Olympics, 2008. The maintenance of hydration status, euhydration rather than hypohydration (the excessive loss of body water), or hyperhydration (where the body has significantly too much water), is imperative to both physical and skill performance improvement and therefore success.

Having been commissioned to assess the activity profile and therefore physical demands of hockey umpiring, Dr Sunderland's research led to the production of a training manual in 2010, which is now used by international umpires from around the world. The officials manager of the International Hockey Federation, confirms: "The research undertaken by Dr Caroline Sunderland and her team at Nottingham Trent University into the distances, types and intensities of running that International Umpires perform in individual matches and at Tournaments, led to the creation of the first ever fitness training programme for Umpires."

Dr Sunderland's research has improved exercise performance in the heat for both elite and recreational athletes across a range of sports. The head coach of Wales Hockey sums up the value of her work: "Dr Caroline Sunderland's research has had significant impact across many sports but particularly in elite international hockey. She is the world's leading authority on acclimation for team sports."

Dr Caroline Sunderland's research incorporates three inter-related topics:

Heat acclimation

Dr Sunderland's research challenged the accepted view, derived mainly from studies focussing on cycling, that heat acclimation could be best achieved through a programme of sub-maximal, steady state exercise. Her research grew out of her theoretical and practical understanding that, for heat acclimation protocols to be both effective and efficient, it is essential to create a high body temperature (Sunderland & Tyler, 2005, Journal of Physiology, 565P. PC6). It proved her hypothesis that high-intensity intermittent acclimation improved games type activity by 33% (Sunderland, Morris & Nevill, 2008, British Journal of Sports Medicine, 42. 327-333) and enhanced field hockey skill performance (Sunderland, Marwood & Nevill, 2003, Journal of Sports Science, 21. 290).

Neck cooling

Dr Sunderland's research was the first to prove that neck cooling improves running performance in the heat (Tyler, Wild & Sunderland, 2010, European Journal of Applied Physiology 110. 1,063-1,074; Tyler & Sunderland, 2011, Journal of Athletics Training 46(1). 61-68; Tyler & Sunderland, 2011, Medicine & Science in Sports & Exercise 43(12). 2,388-2,395).

The research assessed the effect of the cooling collar on the rate of perceived exertion, affect, thermal sensation and running performance in the heat. Findings indicated that the cooling collar may improve performance, but not necessarily feel good, which has important implications for application (Minniti, Tyler & Sunderland. European Journal of Sports Science 11(6). 419-429). Previous research had focused on pre-cooling or non-practical cooling during exercise. Based on her understanding of how the brain regulates exercise performance in the heat, Dr Sunderland hypothesised that cooling the neck region, which has high alliesthesial thermosensitivity, would provide the basis for a practical approach to improving performance. Her hypothesis was proven, leading to the development of a neck-cooling collar which has been adopted and used by other researchers, attracting media attention worldwide.

Improving hockey performance

Dr Sunderland's research demonstrated that:

• field hockey skill and decision-making in international hockey players competing in hot environments is diminished with approximately 2% hypohydration. It also proved that if players remain euhydrated hockey performance is maintained (MacLeod & Sunderland, 2012, Scandinavian Journal of Med & Science in Sports, 22(3). 430-438).
• the hydration status of female international players shows considerable inter-individual variation (MacLeod & Sunderland, 2009, Journal of Strength and Conditioning Research 23(4). 1,245-1,251).
• hockey umpires cover over 6km during a match, with 2.7% of the time spent running at high-speed, although there is large inter-individual variation (Sunderland et al., 2011, European Journal of Sports Science 11(6). 411-417).

There have been articles about the impact of neck cooling on performance inThe New York Times, SHAPE magazine and women's health magazines, bringing the benefits of neck cooling to the recreational audience.

• MacLeod, H. and Sunderland, C., 2012. Previous-day hypohydration impairs skill performance in elite female field hockey players. Scandinavian Journal of Medicine and Science in Sports, 22(3). 430-438.
• Tyler, C.J. and Sunderland, C., 2011. Neck cooling and running performance in the heat: single versus repeated application. Medicine and Science in Sports and Exercise, 43(12). 2,388-2,395.
• Sunderland, C., Pearce, E., Taylor, E. and Spice, C., 2011. Activity profile and physical demands of male field hockey umpires in international matches. European Journal of Sports Sciences, 11(6), 411-417.
• Tyler, C.J., Wild, P. and Sunderland, C., 2010. Practical neck cooling and time-trial running performance in a hot environment. European Journal of Applied Physiology, 110. 1,063-1,074.
• Sunderland, C., Morris, J.G. and Nevill, M.E., 2008. A heat acclimation protocol for team sports. British Journal of Sports Medicine, 42, 327-333.
• Sunderland, C., Marwood, S. and Nevill, M., 2003. Effect of heat acclimatization on field hockey skill performance. Journal of Sports Sciences, 21. 290.