Physical characteristics of experienced and junior open-wheel car drivers

Prompted hands-free drinking improves simulated race car driving in a hot environment

Race car drivers are often hypohydrated during a race. The FluidLogic drink system is a hands-free, prompted drinking system that is hypothesized to increase the likeliness of drivers' consuming fluids and thereby mitigating hypohydration. To test the hypothesis, 20 elite professional race car drivers participated in a 2-day cross-over study in which they drove on a race simulator in an environmental chamber that was heated to regulation cockpit temperature (38°C). Drivers used either the FluidLogic drink system or a standard in-car water bottle system (Control) on one of each testing day. The results indicated that there was consistent fluid consumption with the FluidLogic system, while the Control condition elicited fluid consumption in bolus doses. The Control condition was associated with moderate (0.5%) increased core body temperature (P < 0.05) and substantial (3.3%) increased urine-specific gravity (P < 0.001) as compared to the FluidLogic condition. Driving performance metrics indicated that lap times during the Control Condition were 5.1 ± 1.4 (4.1%) seconds slower (P < 0.05) than the FluidLogic Condition, due to driving errors that occurred in the high-speed corners. Based on these results, prompted hands-free drinking can mitigate hypohydration and performance loss in automobile racing drivers.

Responses of Driver-Athletes to Repeated Driving Stints

PURPOSE

The purpose of this study was to examine and quantify the effect of repeated driving stints on the physiologic, metabolic, and hormonal responses of three professional endurance driver-athletes.

METHODS

Core body temperature, HR, and physiological strain index were recorded during the Rolex 24 Hours of Daytona endurance race using the Equivital Life Monitor system. Blood glucose was monitored continuously during the event using a FreeStyle Libre Pro (Abbott, Alameda, CA). Alpha-amylase and cortisol were sampled immediately before the beginning of a stint and immediately after.

RESULTS

First-stint overall and individual driver-athlete responses were similar to those reported in the literature. Later-stint responses diverged from the literature. Reductions in initial core temperature, absence of increases in HR and physiological strain index, and altered glucose and hormonal responses were each observed in the later stint.

CONCLUSION

The data support previous research showing that motorsports has a measurable physiological, metabolic, and hormonal effect on the driver-athlete. This study also shows that multiple stints elicit responses that deviate from the published literature on single-stint events. This study is also particularly interesting in that it represents one of the first times that longitudinal data have been gathered on endurance racing driver-athletes.

The Physiology of Auto Racing

INTRODUCTION

Auto racing poses a unique set of physiologic challenges for athletes who compete in this sport. These challenges are not widely recognized due to the limited amount of original research in this field and the diffuse nature of this literature. The purpose of this article is to review the major physiologic challenges of auto racing and summarize what is currently known about athletes in this sport.

CONCLUSIONS

The physical stressors of either driving or servicing the race car are overlaid with particular environmental challenges associated with racing (e.g., thermal, noise, carbon monoxide exposure) that increase the physiological stress on motorsport athletes. Physical stress reflects the muscular work required for car control and control of posture during high gravitational (g) loads: factors that predispose athletes to fatigue. The physiologic effects of these stressors include cardiovascular stress as reflected by prolonged elevation of heart rate, cardiac output, and oxygen consumption in both driver and pit athletes during competition. Psychological stress is evident in autonomic and endocrine responses of athletes during competition. The thermal stress of having to compete wearing multilayer fire suits and closed helmets in ambient temperatures of 50°C to 60°C results in the ubiquitous risk of dehydration. Published data show that both drivers and pit crew members are accomplished athletes with distinct challenges and abilities. There are gaps in the literature, especially in regard to female, older adult, and child participants. Additionally, minimal literature is available on appropriate training programs to offset the physiological challenges of auto racing.

V˙O2peak, Body Composition, and Neck Strength of Elite Motor Racing Drivers

PURPOSE

Automobile racing is widely known to be physically demanding; however, there is no published information comparing the physical fitness variables of elite-level race car drivers across various competitive championships.

METHODS

We documented the body composition, peak oxygen consumption (V˙O2peak), and isometric neck strength in a sample of elite race car drivers currently competing in Formula 1, IndyCar, NASCAR, and International Motor Sports Association sports car racing (IMSA GTD), to determine current human performance benchmarks and establish goals for drivers wishing to compete in these series.

RESULTS

Percent body fat was significantly (P < 0.001) lower in Formula 1 drivers (8.1% ± 1.7%) as compared with the other series, with IndyCar (17.4% ± 1.7%) and NASCAR (17.3% ± 4.6%) being less than IMSA GTD (24.9% ± 1.8%). Percent lean mass followed the same trend as percent body fat. IMSA GTD had not only the highest percent body fat but also the lowest (P = 0.001) V˙O2peak (45.2 ± 2.1 mL·kg·mL) compared with Formula 1 (62.0 ± 6.0 mL·kg·mL), IndyCar (58.05 ± 6.40 mL·kg·mL), and NASCAR (53.2 ± 4.1 mL·kg·mL). Isometric neck strength was the highest in Formula 1 and IndyCar drivers as compared with IMSA GTD and NASCAR drivers.

CONCLUSION

These results support the hypothesis that the varying physical demands of each competition series require different physical fitness levels of drivers. These benchmarks can be used by exercise professionals to better prepare athletes for competition.

Is the cross-over effect of a unilateral high-intensity leg extension influenced by the sex of the participants?

Background

While performing a unilateral muscle contraction, electrical muscle activity also arises in the contralateral homologous muscle, muscle group, or limb. When the muscle contraction induces muscle fatigue, females show not only a greater resistance than males but also a reduced contralateral muscle activation. The study aimed at investigating whether, during a high-intensity 30-s unilateral maximal effort isometric leg extension exercise, the contralateral non-exercising limb (NEL) knee extensor muscle activation would differ between females and males.

Methods

Twenty participants, 11 females (23.80 ± 2.15 years old) and 9 males (26.50 ± 2.45 years old), performed a unilateral 30-s exercise while surface electromyography (sEMG) was measured from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) on both limbs. The maximal voluntary contraction (MVC) was measured for both the exercising limb (EL) and the NEL before (MVC PRE) and after (MVC POST) the 30-s exercise to assess muscle fatigue.

Results

While both females and males exhibited muscle fatigue in the EL (p = 0.015), females exhibited a lower MVC reduction than males (p = 0.042), suggesting that females were less fatigued than males. Although no muscle fatigue, i.e., no MVC force reduction was found in the NEL for either group before and after the 30-s exercise, the muscle activity of the VL was found to be of greater magnitude during the MVC POST only for females (p = 0.047) while it remained unchanged for males. During the 30-s exercise, the force output of the EL decreased only for males (p = 0.029) while females showed a preservation of the force output (p > 0.05). The sEMG activity of the NEL during the 30-s unilateral exercise increased for both groups in all measured muscles (all p-values < 0.03).

Conclusions

Likely, different underlying muscle fatigue mechanisms occurred in the EL between females and males. Yet, our findings suggest that the cross-over effect to the NEL during the 30-s exercise occurred in a similar fashion in both groups. The current study suggests that the contralateral muscle activation seen with a unilateral exercise is independent of the sex of individuals. Therefore, unilateral training or rehabilitation-based protocols would similarly impact females and males.

Bioenergetical and Cardiac Adaptations of Pilots to a 24-Hour Team Kart Race

This study aimed to evaluate energy expenditure (EE) and heart rate (HR) response in kart pilots to successive driving bouts during a 24-hour team race. Eight adult male pilots (22.8 ± 4.1 years) participated to a team 24-hour speedway kart race in Le Mans (France). They alternatively piloted a 390 cm kart. Each relay was 45 minutes long and each pilot performed 4 relays. For each pilot, mean speeds were calculated from lap-to-lap duration recordings using a telemetric infrared timing device. Heart rate values were recorded continuously on 5-second intervals using a portable cardiometric device. Total energy expenditure (EET) and physical activity ratio (PAR) were determined by accelerometry. To pilot a kart during 45 minutes at a mean speed around 62 km·h induces a 300-kcal EET, corresponding to a 5.6-Mets PAR. This effort is responsive for a 73 b·min increase in HR, from 84.1 ± 7.6 to 157.4 ± 11.0 b·min (82% maximal heart rate intensity). However, during this relay period, HR values seemed independent to mean speed performance and bioenergetical values. Thus, in the context of the 24-hour team race, the variability in effort made during each relay and relay succession did not alter bioenergetical adaptation of pilots to kart driving. The high EE and HR values would be better explained by both emotional stress and environmental constraints such as speedway configuration and vibrations. The way how these factors specifically influence bioenergetical demand, and their relative importance, has to be specified to optimize training procedure and recommendations.