Biological Rhythms and Training Timing: Matching Optimal Workout Windows for Morning vs. Evening Types

Why Some People Are Superb in the Morning and Others Only Peak in the Evening

Everyone has a different “chronotype.” According to the Horne-Östberg scale, humans can be classified into 4 types:

• Strong Morning: 20% of the population
• Moderate Morning: 30% of the population
• Moderate Evening: 30% of the population
• Strong Evening: 20% of the population

Different chronotypes have distinct daily rhythms in body temperature, cortisol, testosterone, and reaction time, which directly affect the optimal training window.

4 Physiological Rhythms and Athletic Performance

1. Body Temperature Rhythm

Core body temperature fluctuates about 0.5–1°C daily:

• Morning types: low point at 4–5 AM, high point at 4–5 PM
• Evening types: low point at 6–7 AM, high point at 6–7 PM

When body temperature is at its peak, muscle strength is roughly 5–10% greater, nerve conduction is 7% faster, and flexibility increases. This is the “optimal physical performance window.”

2. Cortisol Curve

Cortisol helps enhance alertness and energy mobilization:

• Morning types: peak at 6–7 AM, begins declining at 14:00
• Evening types: peak at 8–9 AM, only begins declining at 16:00

If a morning type trains at 6 AM, they ride right along their cortisol peak; an evening type training at 6 AM is “flying against the wind.”

3. Testosterone (Males)

• Morning types: peak at 6–8 AM
• Evening types: peak at 7–9 AM
• Both have a second smaller peak at 18:00

The optimal window for strength training usually coincides with the testosterone peak.

4. Reaction Time

• 8–10 AM: best for technical sports
• 4–6 PM: best for explosive power and maximal strength
• After 8 PM: reaction time slows down, injury risk increases

Optimal Training Windows for the 4 Personality Types

Strong Morning (naturally awake at 5 AM)

• 5–7 AM: Long Zone 2 aerobic work (morning cortisol is high, fat-burning efficiency is good)
• 7–10 AM: Technical sessions (pedaling drills, intervals)
• 4–6 PM: Strength training + short VO2max intervals
• Avoid: High intensity after 7 PM (it will affect sleep)

Moderate Morning (alert when waking at 7 AM)

• 6–9 AM: Aerobic and technical training
• 5–7 PM: FTP, strength training
• Avoid: After 8 PM

Moderate Evening (still tired when waking at 8 AM)

• 2–4 PM: Aerobic training
• 5–7 PM: High intensity, strength training (this is the golden window for evening types)
• Avoid: High intensity before 7 AM

Strong Evening (only alert at 10 AM)

• 3–5 PM: Technical training
• 6–8 PM: High intensity, strength training (second testosterone peak + body temperature peak)
• Avoid: All training before 9 AM

Most Races Are in the Morning—What Should Evening Types Do?

The problem: the vast majority of road races and cycling challenges start at 6–8 AM. Are evening types at a disadvantage?

Biological clock shifting strategy (starting 14 days before the race):

1. Wake up 15 minutes earlier each day (for 14 consecutive days)
2. From 14 days before the race, finish breakfast 1 hour earlier
3. From 7 days before the race, do 30 minutes of easy riding/running at 6 AM daily (to get morning light exposure)
4. From 3 days before the race, move all training to the morning

Research shows that 14 days of early-morning training can shift the biological clock by about 1.5–2 hours. While it cannot completely eliminate the evening-type disadvantage, it can narrow the performance gap from 8% to 3%.

Coping with Cross-Time-Zone Races

Racing abroad (e.g., Tokyo, Chiang Mai, Singapore):

• Each time zone crossed requires about 1 day of jet-lag recovery
• Start gradually adjusting sleep time 1 week before the race
• Get morning light exposure immediately upon arrival
• Align the first meal with the local time zone
• Supplement with melatonin (0.5–3 mg) to help adjust quickly

Self-Assessment of Your Chronotype

The simplest method: ask yourself 3 questions

1. Without an alarm clock, what time would you naturally wake up?
2. During which part of the day do you feel most energetic?
3. How much later do you go to bed on weekends compared to weekdays?

Answers:

• 5–6 AM, morning, < 1 hour → Strong Morning
• 6–7 AM, morning, 1–2 hours → Moderate Morning
• 7–8 AM, afternoon, 2–3 hours → Moderate Evening
• After 8 AM, evening, > 3 hours → Strong Evening

Alternatively, search online for the “MEQ Chronotype test”—it takes 5 minutes to quantify your type.

Conclusion

Biological rhythms are not superstition; they are real physiological curves. Forcing morning types to train in the evening and evening types to train at dawn diminishes results. Understanding your chronotype and scheduling high-intensity training during the triple peak of body temperature, cortisol, and testosterone can increase effective stimulus by 5–10% without adding training volume. The prerequisite is allowing flexibility in your daily routine; if you are locked into work hours, at least schedule your weekend long rides during your own “golden window.”

Related Reading

• Chronobiology and Athletic Performance: Your Fitness Has a Daily Peak
• Circadian Rhythm and Athletic Performance: Research on Optimal Training Times
• Circadian Rhythms in Athletic Performance: What Time Is Best for Training?
• Chronobiology and Athletic Performance: Your Strongest Moment of the Day