What is the Best Time to Work Out: Morning or Afternoon?

Fitness enthusiasts often debate whether workouts should be scheduled bright and early or whether evening sessions are more effective. Surprisingly, science suggests that there isn't a one-size-fits-all answer. Instead, our bodies are guided by internal biological clocks known as circadian rhythms, which influence everything from hormone production and metabolism to muscle readiness and mental alertness.

Understanding these rhythms can help you align your workouts for better performance, recovery, and health.

In this article, we’ll explore the pros and cons of workout timings and how to identify the best time to work out to maximize your fitness gains.

How do circadian rhythms and hormones affect your workout?

Our bodies follow a roughly 24-hour cycle governed by a “central clock” in the brain and various peripheral clocks in organs and muscles. These clocks cause physiological factors like hormone levels, core body temperature, and energy metabolism to rise and fall at different times of the day. Let’s discuss each of these.

1. Core body temperature

Your internal temperature is lowest in the early morning (making muscles stiffer) and peaks by late afternoon or early evening. A higher core temperature warms up your muscles and improves muscle fiber contractility and power output. This partly explains why people often feel strongest and fastest later in the day.

2. Hormones: Cortisol and Testosterone

• Cortisol (a stress hormone) surges shortly after waking and then declines to its lowest late at night. Although it has a bad reputation, in moderate amounts, it mobilizes energy (converting glycogen to glucose) and increases alertness, which is helpful for fueling a morning workout.

• Testosterone is important for muscle growth and recovery. It is highest in the early morning and lowest in the evening. Higher testosterone in the morning might aid muscle protein synthesis and post-exercise muscle repair, although the effect on immediate performance is negligible.

3. Energy and alertness

Many people naturally feel groggiest upon waking and more alert by midday. Mental alertness and reaction time improve as the day progresses, peaking later in the afternoon alongside physical performance markers.

Your chronotype (whether you’re a “morning lark” or “night owl”) also matters. Early birds feel energetic sooner, while night owls may hit their stride later in the day. Each person has different chronotypes.

4. Sleep-wake cycle

Exercise timing can influence your sleep cycle. Morning or early afternoon workouts tend to shift your circadian rhythm earlier (meaning you feel sleepy earlier at night), whereas late-evening exercise can push your internal clock later.

For example, exercising at 7 a.m. or 1 p.m. has been shown to nudge people to an earlier sleep schedule, while a 7–10 p.m. workout can delay melatonin release and bedtime, especially if you go straight from workout to bed.

Muscle performance is usually highest later in the day. The body is least warm (and possibly least prepared) in the early morning and hormones like cortisol and testosterone peak in the morning. Keep these factors in mind as we examine specific workout times.

Morning Workouts:

Time: 5 a.m to 10 a.m

Morning workouts can feel invigorating once you get moving. Many people find a sunrise run or early gym session boosts their mood and consistency.

Benefits of morning exercise

1. Enhanced fat burning

Morning workouts, especially before breakfast (fasted), may have an edge in burning fat. In the early hours, levels of hormones that mobilize fat (like cortisol and growth hormone) are elevated, priming your body to use fat for fuel.

Early in the morning, your hormonal profile predisposes you to a better fat metabolism, which can aid in weight loss. Some research even suggests that morning exercise can reduce appetite during the day, helping to prevent overeating.

Disadvantages of morning workouts

Morning workouts come with several challenges, especially for those who are not naturally early risers. Waking up early to exercise requires discipline and may cut into sleep if bedtime is not adjusted.

Lack of sleep can negatively affect performance, recovery, and overall health. Additionally, your body temperature and muscle flexibility are lower in the early hours, which can increase the risk of injury if you skip a proper warm-up.

Afternoon Workouts:

Time: 12 p.m. to 5 p.m.

Our body temperature and reaction time naturally reach a high point in the afternoon, and many people feel a surge of energy after a midday meal. Science often points to late afternoon as the peak performance window for exercise.

Benefits of afternoon exercise:

1. Peak physical performance

Multiple studies show strength, power, and endurance tend to peak in the late afternoon or early evening. Athletes have been found to lift more weight, jump higher, and run faster later in the day compared to morning.

In fact, a review of world records and maximal efforts found they’re disproportionately achieved in the late afternoon/early evening. This performance edge is linked to higher body temperature, warming your muscles, and greater nervous system activation as the day goes on.

The afternoon is advantageous if you’re aiming for personal bests in strength or speed.

Disadvantages of afternoon exercise

Many people who are busy with work or school find afternoon workouts difficult to schedule. Most do not have enough time for a long lunch break, and by the time they are free, it is often early evening.

Another issue is the common energy dip that occurs between 3 and 4 p.m. If you feel sleepy or sluggish after lunch, it can be hard to get motivated to exercise, even though light movement might help improve alertness once you begin.

In many regions, the afternoon is the hottest part of the day, which increases the risk of overheating and dehydration during outdoor workouts. It is vital to stay hydrated or move your training indoors.

If your schedule only allows for exercise after work, you may have to deal with crowded gyms during peak hours and will have to battle the traffic.

Timing your lunch is also essential. Exercising immediately after a heavy meal can make you feel slow or uncomfortable. Eating a lighter lunch or waiting at least one to two hours before working out is better.

Evening workouts:

Time: after 6 p.m

Evening workouts are typical for those who can’t squeeze in exercise earlier. Many people head to the gym after work or run in the evening.

Benefits of evening exercise

1. Perfect time for strength training if you are a night owl

An early evening workout session is particularly great for a night owl. If you hit the gym around 6–7 p.m., your core temperature is still elevated from the day, and your muscles remain primed.

You can often perform nearly as well as at 4 p.m. If you are a night owl chronotype, you might feel even stronger in the early evening.

Disadvantages of evening workout

Exercising in the evening has potential downsides, especially if the session is intense or ends too close to bedtime. Vigorous workouts increase adrenaline, cortisol, and core body temperature, all of which can interfere with sleep.

High-intensity training late at night can delay the natural cooling and calming of the nervous system, making it harder to fall asleep and stay asleep. Studies have shown that workouts lasting over 90 minutes in the late evening are linked to poorer sleep quality and more nighttime awakenings.

Experts recommend finishing intense exercise at least 2 to 3 hours before bed to allow the body to wind down. Late workouts can also shift your internal clock. Exercising under bright lights between 7 and 10 p.m. may delay melatonin release and push your sleep schedule later. This effect is more pronounced in early sleepers and may make it harder to maintain an early bedtime.

Additionally, by nighttime, muscle-building hormones like testosterone levels are at their lowest for the day. While this does not prevent gains, it may reduce the body’s short-term anabolic environment.