Tuesday, July 29, 2014

Psychological and physiological demands of F1

Dr Robert Child - Elite Sport Group, United Kingdom
Grand Prix motor racing represents the pinnacle of engineering, applying space age materials and technology to the design and construction of Formula 1 cars. Despite the huge focus on the cars, which costs hundred of millions of pounds to develop, improving the performance of the driver provides a frequently overlooked opportunity to enhance the performance of driver-car package.

Superficially competing in a Grand Prix is a much less physiologically challenging than riding a stage of the Tour de France, but closer analysis reveals this is not the case. Completing in a Grand Prix places extreme requirements for strength, fitness and mental concentration, which can push even the fittest drivers to the limits of their physical capacity.

Loads on the body

One of the most obvious challenges for the modern Formula 1 driver is coping with the huge forces applied to the body. These are usually expressed relative to the force of gravity (g) and at rest a force of 1g acts on the body. Acceleration, deceleration and cornering all apply loads to the body and high performance road cars such as the Porsche 911 generate around 0.7g accelerating, 1g braking and 1g cornering. In contrast, a 2014 F1 car generates up to 1.2g accelerating, 5g braking and 6g cornering. These forces are applied to the whole body, but particularly affect the head as this is only supported by the neck. In fast corners such as Silverstone's Copse corner, or turn 8 at Istanbul Park the lateral load on the neck is equivalent to half the drivers body-weight. Even under braking the forces applied to the body are similar to those experienced by fighter pilots. The application of high g forces results in large fluid shifts within the body, which even in the physically fit causes blacking out at around 6g (ref. 5). Modern day fighter pilots can safely be exposed to 10g by minimizing fluid shifts with pressurized suits, however these are too heavy and cumbersome for use in Formula 1.

Figure 1 relative maximum g force for road and Formula 1 cars

The exceptionally high loads generated by modern Formula 1 cars, require drivers generate high muscle forces. These typically involve isometric muscle activation (where muscle length is constant); and eccentric muscle activation, where muscles are forced to lengthen under load. Both types of muscle activation generate very high muscle forces on fast or bumpy tracks. It is the generation of high muscle forces rather than lactic acid, which actually produces muscle damage (ref. 2). This is accompanied by soreness and weakness 3 and impairments in neuromuscular feedback, resulting incorrect perceptions of limb position and muscle force generation (ref. 11). This means that as a Grand Prix progresses it becomes increasingly difficult for drivers to apply the correct level of throttle to get optimal drive out of corners and apply the correct braking force to have the ideal corner entry speed. One overt manifestation of impaired neuromuscular feedback is driver errors. These can result in excessive throttle when exiting corners, causing the back end to slide and lock ups under braking.

The need to keep cool

The accumulation of heat is another challenge faced by Grand Prix 1 drivers, which can significantly impair driving performance. The engines powering 2014 Formula 1 cars are around 40% efficient at converting the chemical energy in fuel to mechanical energy. This means that when an engine produces 750 horsepower more than 300,000 Watts of heat must be dissipated to stop the engine overheating. This is equivalent to neutralising the heat output of 150 electric ovens cooking a Sunday roast dinner ! Engine heat is radiated to the driver, adding to his thermal load. This can be a problem even in cool weather because the driver himself generates a significant amount of heat. Humans are much less efficient that Formula one engines and rarely convert more than 25% of the energy available to mechanical work. This means 75% of the energy available from carbohydrates and fat that could be used to generate muscle force actually gets converted into heat.

The energy demands of Grand Prix racing have not been directly calculated, but estimates have been made using heartrate data. These suggest an average power requirement of around 150 Watts over a 90-minute race, which is significantly lower than power outputs observed in professional cyclists. For example Tour De France riders routinely generate in excess of 400 Watts over the same time period as a Grand Prix. Despite the comparatively low energy demand, the Formula 1 driver still needs to dissipate around 500 Watts of heat to stay cool, about a quarter the heat output of a domestic oven. This can easily be achieved when cycling, as the exposed arms, legs chest and face all provide effective body cooling. In contrast, an F1 driver’s body is completely covered by a fire retardant Nomex® race suit and helmet; which greatly reduces body cooling even with air speeds of 200mph! This makes staying cool a major challenge for the driver, both because of his own heat generation and the heat radiated to him by the car. Racing in hot weather, especially on physically demanding circuits such as Austin Texas, is likely to result in body temperatures in excess of 40C. Such hyperthermia (overheating) can result in heat illness, which elevates brain temperature and compromises normal brain function (ref. 6). For F1 drivers even tiny decrements in cognitive performance have serious consequences. For example being late of the brakes at the end of a straight provides a key on track overtaking opportunity. At 200mph out-braking by one car length equates to being just 50 milliseconds later on the brake pedal; less than a quarter of the time needed to blink. So even small judgement errors can have disastrous consequences!

Sweating is the body’s key response to minimize overheating and with appropriate physical training sweat rates of 2 to 2.5 liters per hour, can be achieved. This means that over a typical 90 minute Grand Prix drivers can potentially lose 3 to 3.75 liters of sweat, which around 5% of body weight. The ability of drivers to take on fluid during a Grand Prix is often limited to 500ml; which is just a fraction of their sweat losses. This means Formula 1 drivers can finish Grand Prix more dehydrated than professional cyclists who have ridden a 200km mountain stage of the Tour De France. Dehydration of this magnitude is associated with compromised body cooling, higher temperatures of blood flowing to the brain, as well as elevated brain temperatures (ref. 6, 9). When the brain gets too hot its metabolism is altered 8 and its function is impaired which may ultimately resulting in brain injury (ref. 9, 10, 12). Laboratory studies report dehydration of just 2% (less than 1.5 liters of fluid) is sufficient to impair tasks requiring visual-motor tracking, short-term memory and attention (ref. 7). These tasks have some commonality with the mental demands of racing a Grand Prix car. Therefore the combination of high sweat losses and brain temperature suggest cognitive performance may be impaired in the latter phases of a Grand Prix. Driver errors may be a manifestation of this; such as missing an apex. Serious judgment errors can have a direct impact on the race outcome; such as flat spotting tyres, failing to engage the speed limiter, overshooting the pit box and off track excursions.

Figure 2 Sweat losses, fluid intake and dehydration at hot Grand Prix and a mountain stage of the Tour de France
Cool dry weather conditions greatly reduce the physiological demands of Grand Prix racing as the forces applied to the driver are lower and there is less heat for the driver to dissipate. However, when rain falls there are additional psychological demands for the driver. Poor visibility caused by spray makes the sighting cues used by the driver for braking and track position more difficult to spot, creating even higher demands for sustained concentration. Similarly rain produces rapidly changing track characteristics, which increase concentration demands particularly when drivers are trying to maximize performance on every lap.

Understanding the physiological demands of Grand Prix racing is of more than just of academic interest to Formula 1 teams. With understanding of the limiting factors to human performance, it is possible to increase the overall effectiveness of the driver-car package. Every Formula 1 team employs fitness trainers to improve the physical condition of the drivers. Invariably they focus on resistance training (typically with weights) to increase muscle strength, which over time greatly reduces susceptibility to muscle injury 1. Endurance work is also included to improve cardiovascular fitness and sweating responses, so that drivers can cope with long hot races more easily. However physical conditioning only provides a limited level of adaptation to the demands of Grand Prix racing. More advanced Formula 1 teams have invested in giving their drivers advantages far beyond simply improving driver fitness and providing a competitive car.

One such team is McLaren, who were one of the first Formula 1 teams to experiment with a driver cooling system. This was specifically designed to be lightweight, and as consequence was only suitable for cooling the head (http://elitesportgroup.org/clients-endurance-training/mclaren-f1-nutrition/). Despite this, it still provided an effective strategy for minimizing the risk of brain hyperthermia.

Formula 1 teams give their drivers carbohydrate electrolyte drinks prior to and during Grand Prix races. This practice has become popular to help maintain blood glucose levels (essential for brain function) and to replace some of the fluids and electrolytes lost as sweat. Many sports drinks such as Red Bull also contain caffeine, which is the primary ingredient responsible for improved alertness and reaction times (ref. 4). Caffeine can have adverse effects such as being a mild diuretic, so potentially contributing to dehydration. Caffeine can also reduce response accuracy in tasks with high cognitive demands, which could be detrimental to performance.

Food supplements are now available which provide the same benefits for mental performance as caffeine, but with fewer side effects. They have the potential to improve pre race hydration and cognitive performance in mentally demanding tasks, particularly in stressful environments. Recent research trials have also identified a spectrum of ingredients, which are useful for reducing dehydration and decreasing muscle damage. Although some of these nutrients are included in commercial supplements, they are present at too low a level to actually be effective. Provision of nutrients at efficacious levels can provide significant advantages regarding hydration, muscle performance and mental functioning. To overcome these issues many professional teams source scientifically formulated non-commercial products. Such products have already been used in successfully in competition at events such as Tour de France and some are undergoing evaluation by the military.

Dr. Robert Child is a specialist in performance biochemistry and human physiology. He is currently consultant to MTN-Qhubeka professional cycling team and the UK military. He previously worked with McLaren Formula 1, was Head of Nutrition for the Cervelo Test Team and was Head of Research for the sports nutrition company Maximuscle. His experience in top-level sport is extensive having worked with World Champion and Olympic medalists from British Sailing, Olympic Boxing and Olympic Swimming. He can be contacted via the Elite Sport Group (http://elitesportgroup.org/contact-the-elite-sport-group/).

1) Brown SJ, Child RB, Day SH, Donnelly AE. Exercise-induced skeletal muscle damage and adaptation following repeated bouts of eccentric muscle contractions. J Sports Sci. 1997 Apr;15(2):215-22

2) Child RB, Brown SJ, Day SH, Saxton JM, Donnelly AE. Manipulation of knee extensor force using percutaneous electrical myostimulation during eccentric actions: effects on indices of muscle damage in humans. Int J Sports Med. 1998 Oct;19(7):468-73.

3) Child R, Brown S, Day S, Donnelly A, Saxton J (1999) Changes in indices of antioxidant status, lipid peroxidation and inflammation in human skeletal muscle after eccentric muscle actions. Clinical Science (1999) 96, 105–115.

4) Giles G, Mahoney C, Brunyé T, Gardony A, Taylor H, Kanarek R. Differential cognitive effects of energy drink ingredients: caffeine, taurine and glucose. Pharmacology Biochemistry and Behavior. Volume 102, Issue 4, October 2012, Pages 569–577.

5) Henry J. Gauer O, Kety S. Kramer K. Factors maintaining cerebral circulation during gravitational stress. J Clin Invest. Mar 1951; 30(3): 292–300.

6) Kanaya N, Kobayashi Y, Yamakage M, Tsuchida H, Watanabe A, Namiki A Cerebral blood flow velocity and electroencephalogram for the evaluation of intraoperative brain function during intrathoracic hyperthermia]. Masui. 1993 Mar;42(3):450-4.

7) Lieberman HR. Hydration and cognition: a critical review and recommendations for future research. J Am Coll Nutr. 2007 Oct;26(5 Suppl):555S-561S.

8) Nybo L, Møller K, Volianitis S, Nielsen B, Secher N. Effects of hyperthermia on cerebral blood flow and metabolism during prolonged exercise in humans. J Appl Physiol (1985). 2002 Jul;93(1):58-64.

9) Nybo L, Secher N, Nielsen B. Inadequate heat release from the human brain during prolonged exercise with hyperthermia. Journal of Physiology (2002), 545.2, pp. 697–704.

10) Nybo L. Brain temperature and exercise performance. Exp Physiol 97.3 (2012) pp 333–339

11) Saxton JM, Clarkson PM, James R, Miles M, Westerfer M, Clark S, Donnelly AE. (1995) Neuromuscular dysfunction following eccentric exercise. Med Sci Sports Exerc. 27, 1185-93.

12) Yarmolenko PS, Moon EJ, Landon C, Manzoor A, Hochman DW, Viglianti BL, Dewhirst MW. Thresholds for thermal damage to normal tissues: an update. Int J Hyperthermia. 2011;27(4):320-43.