Fitness and weight can be difficult for anyone to maintain. That's further complicated when your job involves travelling around the world -- across different time zones, cuisines and cultures -- for 24 weeks of the year. That's the baseline challenge facing every Formula 1 driver.
And then there are the races themselves, all of which are physically demanding, but some more so than others. Take Sunday's Singapore Grand Prix, for example, where oppressive heat and humidity will push competitors to their physical limits.
Drivers' bodies are managing an intricate balancing act: they must be strong enough to withstand gravitational forces of up to about 6 G's, while still light enough so as not to be additional ballast in the car. And that balancing act must be performed for the entirety of an F1 season of nine-plus months.
During a typical grand prix, drivers can lose 2 to 3 kilograms (4.4-6.6 pounds) in sweat alone, depending on their weight and height, and as much as 4 kg (8.8 pounds) in Singapore for taller drivers. That's approximately 3% to 4% of their bodyweight.
With such emphasis on drivers' weights, one of the biggest difficulties is maintaining muscle mass throughout the course of the season. So how do they do it?
"You take small opportunities throughout the season to push a bit more," Aleix Casanovas, George Russell's trainer, told ESPN. "So it goes back to having data from previous years. When there's an easier race weekend, you push a bit more thinking about the future."
For example, he says, from the start of the season at the Bahrain Grand Prix heading into the Saudi Arabian Grand Prix, the latter is much hotter and more physically taxing, so drivers can push the training harder in the buildup to the season opener. Monza is similar. There are "not that many corners, a lot of straights, so you can actually push a bit more that week. Thinking about the future and race week like Singapore, which you know is going to be heavy, you need to taper down exercise, so you will train a little bit less then."
Each driver is different, but taller drivers such as Esteban Ocon and Alex Albon, both of whom are 1.86 meters (6-foot-1), tend to have more difficulty maintaining the sweet spot compared with shorter drivers such as Yuki Tsunoda, who is 1.67m (5-6). Next year, drivers' minimum weight is increasing from 80 kg (176 pounds) to 82 kg (181), which should help taller drivers' overall health and help them avoid illness.
Most drivers will train heavily in preseason, building their strength and fitness to start in the best possible shape, and then look for opportunities to push again over the course of the season depending on the upcoming race. Ferrari's Charles Leclerc said there are three key training moments.
"There is preseason, where you see the most improvement because that is when we have the most time to train," he said. "Within the season, when it's all about maintaining that fitness level and it's less intense training and all about maintaining your strength. And then you've got the break in August, when it's good to take a complete break and not really train anymore and just slow down, and then maintain until the end of the season, when I can push again at the gym."
If you find yourself smuggling exercise equipment in your luggage and choosing hotels because of their gym facilities, so you can stay fit while away, you might relate. Considering F1 is a travelling circus, you work with what you've got.
Casanovas has been with Russell for eight years, so the hotels are familiar to him. If there is a new hotel, though, he says: "I call them before and ask them to send me pictures of what equipment they have, but I travel always with a bit of kit. There are a few things we use everywhere in the world."
He refers to a dynamometer, which is a device that measures force, and is used for leg, neck and arm strength, but no resistance bands as he says they don't provide a stimulus big enough to create a stress that will improve strength. While the workouts might vary from week to week depending on the demands on a driver, a typical grand prix weekend has a familiar cadence.
"From Thursday, we might do a bit of cardiorespiratory training, and it depends on where we are in the world, sometimes we do a little bit of high-intensity strength training but low volume," Casanovas says. That means "a few reps of neck training at high intensity but with many repetitions; that means there's not a lot of fatigue, and it's isometric, so there's even less fatigue. Depending on the race, you will always do some cardiorespiratory training and strength training, but ... you'll prioritise one or the other."
Naturally, fatigue, jet lag and emotional wellbeing come into the picture, too, and there's a lot of adjustment based on how the drivers are feeling.
"You have to programme smartly, but you need to adapt as well," Casanovas says. "If a race weekend doesn't go well, it's really hard for a driver to go hard on a Tuesday, just mentally. Emotionally, you are not there, but also maybe sleep, and there's a million factors there.
"When you cross around six hours west [like to the U.S.], we know it takes four or five days to go back to normal strength levels, and we've seen that in many sports. For those type of races, you prioritise more cardiorespiratory training, so it feels better and easier, and you don't want to hit a [personal best] in neck strength when you go to the U.S."
The 24 races on the calendar can be enough training on their own.
"You try to prepare yourself as much as you can before the season starts, just because you know you're going to be fighting through jet lag and so many races," Stake F1's Zhou Guanyu said. "On the physical side, I think you get into a point that you're racing fit. You're doing so many races every single weekend and you're constantly in your seat, that really makes life a lot easier because the moment you step in the car, start the season, everything just gets very consistent through into the summer break."
The three-week summer break is not a complete break, as it is possible to lose fitness, and more importantly, lose the adaptation to heat exposure. Casanovas says, "In six days, you lose a lot [of fitness] already. You lose a lot of adaptations to heat as well, which is very important for us -- around 2.5% every day ... when you're not exposed to heat."
In Singapore, that heat adaptation is crucial, as is going into the cockpit for two hours properly fuelled and hydrated and with a stable core temperature.
It's not all bad, though. Although the drivers' nutrition is carefully planned -- Casanovas tells the Mercedes chefs what's on the menu for Russell, and they prepare it -- for Singapore they will eat more than usual to build up the energy in the days prior.
Carbohydrates are the priority for energy, a whopping 5g to 6g per kilo of bodyweight (about 0.08 to 0.1 ounce per pound), as well as protein, macronutrients and fats for recovery.
"Eating that much carbohydrate is not that easy," Casanovas says, "so don't be surprised if you see an athlete before a match or a race eating dessert because you need to top up those carbohydrate stores."