How Does Adequate Sleep Contribute To Optimal Physical Fitness And Performance?

When we think of what makes athletes exceptional, few of us would assume that sleep might play an essential role. But many of the world’s finest athletes say slumber is an essential part of their training routine and crucial in enabling them to perform well.

Serena Williams, for example, endeavors to get eight hours of sleep each night. NBA icon LeBron James strives for eight to ten hours per night, while NFL legend Tom Brady says he goes to bed early and receives at least nine hours of sleep.

It’s no wonder, since sleep plays a key role in metabolism, the growth and regeneration of tissues (such as our muscles), and ensures memory, reaction time and decision making are all functioning effectively. All these mechanisms impact sporting performance.

But it isn’t just athletes whose athletic performance can benefit from adequate sleep. Even novice gym-goers can maximise the benefits of exercise for their fitness and health by getting enough decent sleep each night.

Here are just some of the ways sleep benefits your fitness:

Aerobic fitness

Exercise is excellent for enhancing aerobic fitness. It enhances both aerobic capacity (being able to run or cycle quicker with a heavier burden) and efficacy (meaning your body requires less oxygen to run or cycle at the same tempo).

One contributing factor to enhanced aerobic fitness is the function of the body’s mitochondria. Mitochondria are tiny structures within the cells of the muscles that are responsible for creating the energy the muscle requires during exercise.

Research reveals that inadequate sleep (receiving only four hours a night for five nights) can reduce the function of mitochondria in healthy participants. High-intensity interval training was shown to mitigate these impairments in the short-term (over a five-day period). But, it’s currently unclear how these impairments would influence adaptations to exercise in the longer term, so it’s best to get a decent night’s sleep if improving aerobic fitness is one of your objectives.

Muscle expansion

Sleep is also vital if you’re seeking to build strength or musculature.

Muscle growth occurs when new proteins are added to the muscle structure – a process known as “muscle protein synthesis”. This process is stimulated by exercise and food (specifically protein) ingestion, and can last at least 24 hours after an exertion.

Research demonstrates that even just a few nights of insufficient sleep reduces the muscle protein synthesis response to nutrient intake. This suggests that inadequate sleep may make it tougher for the body to develop muscle.

Anabolic hormones

Hormones act as chemical mediators that contribute to a range of functions throughout the body, such growth and development of tissues. Hormones which are involved with these construction processes can be deemed “anabolic” hormones.

Two anabolic hormones – testosterone and growth hormone, which are released during sleep – may also be crucial for recovery from and adaptation to exercise. These hormones have multiple functions in the body, and are linked to enhanced body composition (lower body fat and higher muscle mass). A higher quantity of muscle mass and lower body fat can be beneficial for exercise and health.

When sleep is restricted to only five hours per night (similar to the quantity of sleep many working adults get), testosterone levels are reduced in healthy young men. Sleep restriction of a similar duration also alters the secretion of growth hormone during sleep. While more research is required, there’s a potential that these hormones may play a role in mediating the relationship between sleep and fitness, due to their link to enhanced body composition.

Refuelling after exercise

Exercise often utilizes glucose (sugar) as a fuel source. Muscles store glucose from the foods we consume in the form of glycogen to satisfy the demands of exercise. Replenishing glycogen stores after exercise is a critical element of the recovery process. It can take up to 24 hours to completely replenish stores, with the correct nutrient intake. The hormone insulin can be needed for muscles to absorb glucose in order to produce glycogen.

Numerous studies demonstrate that insufficient sleep reduces the effectiveness of insulin. This could impact on the body’s ability to replace glycogen stores, with one study revealing reduced muscle glycogen stores after a night of sleep deprivation.

Depleted glycogen stores can impede subsequent exercise performance in the short and long term, so it is crucial to ensure glycogen stores are replenished after exercise.

How to sleep well

Sleep is obviously essential for your fitness, so here are some methods to ensure you get adequate sleep each night:

• Develop a consistent bedtime routine: do things before bedtime that help you unwind and settle down – such as reading a book or listening to relaxing music. A heated shower or bath before bed can also be beneficial as the decrease in body temperature afterwards can help you to fall slumber speedier.
• Create a healthy slumber environment: exposure to light during the night can reduce sleep quality, so attempt to block out as much light as possible. Aim to keep the room chilly, but not too frigid. An environment that is too heated or too chilly can disrupt sleep quality.
• Be physically active during the day: research demonstrates that physical activity is beneficial for sleep quality, so aim to include some exercise or physical activity in your day.
• Keep a consistent sleep schedule: this will help to regulate your sleep-wake cycle, which has been linked to enhanced sleep quality.

If you are attempting to improve your fitness make sure you’re receiving enough high quality slumber – strive for at least seven to nine hours of sleep each night.