Physiological responses for Master Athletes participating in ultra-endurance events in warm climates

 

The issues surrounding extreme heat

Gordon Ramsay ‘The Ironman’ participated in Hawaii in 2015, and unfortunately couldn’t complete the race. This is due to intense heat plummeting 39C which resulted in this body shutting down due to dehydration. In this article, it informs master athletes, including Gordon Ramsay, how the body responds to endurance based exercise in heat during an Ironman triathlon and the potential risks they might face. An abnormality of ± 3.5°C from the resting temperature of 37°C can result in physiological impairments and fatality (Lim et.al, 2008).

 

In cold environments, heat production is vital and beneficial for athletes during exercise. However, exercising in warm climates can have a detrimental effect on athletes due to the metabolic heat load places a considerable burden on the mechanisms that control the body temperature (Wilmore & Costill et.al, 2004). Exercising in warmer environments places greater cardiovascular system stress, and increases heart rate which will influence performance significantly. Ironman is an ultra-endurance triathlon which is situated in Hawaii. Ironman triathlons occur all over the world but its most famous in Hawaii and where Gordon will run his Ironman, where temperatures are extremely warm and humid. The average temperature in Hawaii is 30C during October, which is when the Ironman triathlon takes place. Exercising in this type of environment produces competition between the skin and active muscle due to limited blood supply. The skin requires blood to facilitate heat loss to keep the body cool, through vasodilation. whilst oxygen is essential in the working muscles to sustain activity. Ironman enables participation from 18 years and over. A common participation group in Ironman are the Masters athletic association. Masters athletics is a class of sport of athletics for veteran athletes. Observations have shown that people aged 60 and over are amongst the worst affected by heat due to the inability to physiologically maintain body core temperature during heat, which becomes compromised with age (Kenny et.al, 2010).

 

During Ironman, body temperature will fluctuate greatly. When this occurs your normal temperature can usually be restored by the actions of four effectors: sweat glands, smooth muscle around arterioles, skeletal muscle and endocrine glands. Sweat glands are activated when your skin or blood is heated, impulses are sent to sweat glands via the hypothalamus commanding them to secrete sweat. Therefore, evaporation occurs to provide cooling for the athlete. However, research suggests that women aged 52-62 years exercising in 48C obtained a significantly higher rectal temperature through a heat-exercise session. An explanation of this suggests that women have greater heat storage due to their low whole-body sweating rate (Anderson et.al, 1987). As a result of this, evaporation does not occur, therefore keeping the body cool is less effective. In addition to increasing body temperature, oxygen intake also increases whilst exercising in heat due to the working muscles utilising more glycogen with the demand of producing more lactate compared with exercising in colder environments. A higher oxygen uptake is also required due to increased sweat production and respiration rate due to a greater demand of energy. Therefore, exercising in heat accelerates glycogen depletion and increase muscle lactate, which can result in sensations of fatigue and exhaustion (Wilmore & Costill et.al, 2004). Research has shown that there are substantial changes within the nervous system’s capacity to process information and to activate muscles are associated with age. Studies of motor unit activation have indicated that the maximal discharge in adults older than 67 years was less than in adult’s 21-33-year-old adults (Wilmore & Costill et.al, 2004). It is clearly evident that muscle wastage and weakening acerbates with age due to the result from a loss of functioning motor units.

 

An issue with older participants in Ironman is heat stress. When an individual’s age increase, adults become more susceptible to fatal heat injuries than younger people. This thermal intolerance is due to older people sustaining higher body temperatures regardless of the intensity of exercise than younger counterparts. Heat stress is not accurately reflected by air temperature alone. Other factors contributing to heat stress include humidity, air velocity and thermal radiation (Wilmore & Castell et.al, 2004). In healthy people, the body regulates its core temperature to maintain a near-constant level (about 37C), irrespective of environmental conditions. During Ironman, the increase in metabolic rate above resting levels increases the rate at which heat must be dispersed to the environment to prevent the body temperature rising to a dangerous level (Kenny et.al, 2010). However, impairments of normal thermoregulatory function are more likely to occur to athletes participating in an Ironman triathlon (especially in master athletes) as sweating and skin blood flow cannot facilitate a high rate of heat loss. This is due to core body temperature rising continuously which can lead to illness which is displayed in figure 1.2.

Following from this, hyperthermia is a common result from aerobically exercising in warm climates (Hoffman et.al, 2002). Hyperthermia occurs when body temperature is above 39C which can result in up to 50% of participants requiring medical attention for heat-related illnesses (Armstrong et.al, 1996). According to Tankersley, the older an individual gets, they become more susceptible to hyperthermia than younger people (Tankersley et.al, 1991). If body temperature is not controlled during the event, body temperature could rise to a level that places the individual in great danger, which Gordon Ramsay experienced. To prevent Ramsay feeling the sensations of extreme fatigue, dehydration and dizziness, athletes must decrease their efforts to reduce the heat production as controlling environmental conditions is extremely difficult (Wilmore & Costill et.al, 2004). To prevent heat disorders, fluids should be readily available, and athletes should be required to drink as much as they can, stopping approximately every 10 to 20 minutes in warm temperatures (Wilmore & Costill et.al, 2004). Ramsay should also take into consideration is clothing. Wearing little clothing encourages heat exchange especially when heat stress is a potential limitation to thermoregulation as extra clothing could be a burden. During exercise in heat, sweat output often exceeds water intake, resulting in hypohydraton, which is defined at a body fluid deficit (Sawka et.al, 1984). Therefore, drinking before and during exercise can greatly reduce the negative effects of exercising in heat – refer to figure 1.1 for guidelines for distance runners competing under conditions of heat stress.

 

 

The Solution

During an event such as an Ironman, sweating and water loss from respiration may reduce body water content by 6% to 10%, despite fluid intake during the event. Therefore, athletes including Ramsay need to regularly consume water before and during the race for their performance not to deteriorate. Water plays several critical roles during exercise especially when exercising in heat, which include; red blood cells carry oxygen to your active muscle via blood plasma, water facilitates the dissipation of body heat that is generated during exercise and maintains blood pressure for sufficient cardiovascular function. These factors should encourage athletes to consume more water and to avoid dehydration during exercise in warm climates. According to Miescher, older men aged (61-67yr) showed slower responses to restore plasma volume and plasma osmolality during exercise in heat. Within 30 minutes of drinking, younger males restored these factors within 30 minutes, contrasting with older men which 60 minutes to restore plasma osmolality. Despite the older men obtains a higher rectal temperature, they rated themselves as less thirsty and not significantly hotter than younger men. Miescher stated that these findings suggested that ageing results in a decreased ability to maintain rectal temperature during heat stress due to the lack of perception to keep hydrated (Miescher et.al, 1989).

Another solution for Ramsay is to adapt to a warmer climate prior to the event where physiological changes occur over short periods of time especially if he’s artificially induced in a climatic chamber. These adaptions are termed ‘heat acclimation’ (Kenny et.al, 2012). According to Lorenzo, heat acclimation increased VO2 max by 8% in warm environments and also improved time-trail performance by 8% (Lorenzo et.al, 2010). For Ramsay, reducing physiological strain during the ultra-endurance triathlon is vital, therefore, repeated bouts of low intensity exercise in heat enable rapid improvement in the ability to maintain cardiovascular function and eliminate excess body heat. In addition, after heat acclimation, Ramsay would improve his tolerance towards heat especially at the beginning of exercise where sweating is occurring quickly due to an increase is body temperature (Kenny et.al, 2012). An outcome from heat acclimation is that sweat becomes more dilute, therefore conserving more sodium which prevents heat cramps, and what Ramsay suffered during last years’ attempt.

 

This year, Gordon Ramsay is participating and hopefully completing a sub 12-hour Ironman Hawaii due to the events of last year when he collapsed due to extremely high temperatures resulting in dehydration. In ‘The Scotsman’ Scotland’s national newspaper he stated “I will be back! It’s been the hottest year since living here, making this tough, brutal race even harder.” This article informs Ramsay with the brutality and potential risks of the event, and the importance of water. Water enables the whole body to function correctly allowing performers to perform to their best ability during strenuous events like Ironman. Therefore, Ramsay needs to consider consuming more water before and during the race to complete it this year in an improved time.

Appendices

Figure 1.1

1.	Distance races should be scheduled to avoid extremely hot and humid conditions. If the WBGT is above 26C (82F), consider cancelling the race.
2.	Summer events should be scheduled early morning or evening to minimise solar radiation and unusually high air temperatures.
3.	An adequate supply of fluid must be available before the start of the race, along the racecourse, and at the end of the event. Runners should be encouraged to replace their sweat losses or consume 159 to 300ml every 15 minutes during the race.
4.	Cool or cold (ice) water immersion is the most effective means of cooling a collapsed hyperthermic runner.
5.	Runners should be aware of the early symptoms of hyperthermia, including dizziness, chilling, headache or throbbing pressure in the temporal region, and loss of coordination.
6.	Race officials should be aware of the warning signs of an impending collapse in hot environments and should warn runners to slow down or stop if they appear to be in difficulty.
7.	Organisational personnel should reserve the right to stop runners who exhibit clear signs of heat stroke or heat exhaustion.

These recommendations are based on the position stands published by the American College or Sports Medicine in 1987 and 1995 (Wilmore & Costill et.al, 2004).

Figure 1.2

 

 

 

 

 

 

 

 

 

 

 

 

(González‐Alonso et.al, 1999)

 

 

References

Anderson, R.K. and Kenney, W.L., 1987. Effect of age on heat-activated sweat gland density and flow during exercise in dry heat. Journal of applied physiology, 63(3), pp.1089-1094.

Armstrong, L.E., Epstein, Y., Greenleaf, J.E., Haymes, E.M., Hubbard, R.W., Roberts, W.O. and Thompson, P.D., 1996. Heat and cold illnesses during distance running. Med Sci Sports Exerc, 28(12), pp.377-390.

González‐Alonso, J., Crandall, C.G. and Johnson, J.M., 2008. The cardiovascular challenge of exercising in the heat. The Journal of physiology, 586(1), pp.45-53.

González-Alonso, J., Teller, C., Andersen, S.L., Jensen, F.B., Hyldig, T. and Nielsen, B., 1999. Influence of body temperature on the development of fatigue during prolonged exercise in the heat. Journal of applied physiology, 86(3), pp.1032-1039.

Hoffman, J. 2002, Physiological aspects of sport training and performance, Human Kinetics, Champaign, IL.

Inbar, O., Morris, N., Epstein, Y. and Gass, G., 2004. Comparison of thermoregulatory responses to exercise in dry heat among prepubertal boys, young adults and older males. Experimental physiology, 89(6), pp.691-700.

Kenny, G.P., Yardley, J., Brown, C., Sigal, R.J. and Jay, O., 2010. Heat stress in older individuals and patients with common chronic diseases. Canadian Medical Association Journal, 182(10), pp.1053-1060.

Kenney, W.L., Wilmore, J.H. & Costill, D.L. 2012, Physiology of sport and exercise, 5th edn, Human Kinetics, Champaign, IL.

Lim, C.L., Byrne, C. and Lee, J.K., 2008. Human thermoregulation and measurement of body temperature in exercise and clinical settings. Annals Academy of Medicine Singapore, 37(4), p.347.

Lorenzo, S., Halliwill, J.R., Sawka, M.N. and Minson, C.T., 2010. Heat acclimation improves exercise performance. Journal of Applied Physiology, 109(4), pp.1140-1147.

Miescher, E.L.I.Z.A.B.E.T.H. and Fortney, S.M., 1989. Responses to dehydration and rehydration during heat exposure in young and older men. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 257(5), pp.R1050-R1056.

Rogers, M.A., Hagberg, J.M., Martin, 3.W., Ehsani, A.A. and Holloszy, J.O., 1990. Decline in VO2max with aging in master athletes and sedentary men. Journal of Applied Physiology, 68(5), pp.2195-2199.

Sawka, M.N., Francesconi, R.P., Young, A.J. and Pandolf, K.B., 1984. Influence of hydration level and body fluids on exercise performance in the heat. Jama, 252(9), pp.1165-1169.

STUART MACDONALD. (2015). Gordon Ramsay rescued after collapsing at Ironman event. Available: http://www.scotsman.com/news/celebrity/gordon-ramsay-rescued-after-collapsing-at-ironman-event-1-3915306. Last accessed 16th May 2016.

Tankersley, C.G., Smolander, J., Kenney, W.L. and Fortney, S.M., 1991. Sweating and skin blood flow during exercise: effects of age and maximal oxygen uptake. Journal of Applied Physiology, 71(1), pp.236-242.

Wilmore, J.H. & Costill, D.L. 2004, Physiology of sport and exercise, 3rd edn, Human Kinetics, Leeds.