Early Morning Training: A Runner’s Guide to Making It Work

Many recreational runners have no choice but to train in the early morning. If that sounds like you, you’ve probably felt the frustration of trying to squeeze in a quality session before sunrise.

Due to work and family commitments, I do 95% of my own training immediately after waking up in the early morning. There have been stretches where the effort didn’t seem to translate into results, and I genuinely felt I had hit a ceiling with early morning training.

However, once you clearly understand the drawbacks of early morning training, you can work around them — and still perform on par with runners who train at more favorable times of day.

This article draws on over three years of early-morning-only training. I’ll explain the key disadvantages — and the practical strategies I’ve used to overcome them.

By the end, you’ll have a clear roadmap for improving your running performance even when life limits your training window to the early hours.

Pros and Cons of Early Morning Training

Here is a summary of the pros and cons of early morning training.

I wake up at 4:00 a.m. every morning to run. Most people are surprised by that, but once you build the habit, getting up early stops feeling like a hardship.

Early morning runs typically happen in a fasted state, which is advantageous from a fat metabolism standpoint. A meta-analysis by Vieira AF et al. (2016)※1 confirmed that fasted cardio produces significantly higher fat oxidation rates than exercise performed after eating.

De Bock K et al. (2008)※2 found that six weeks of fasted training increased the expression of fat oxidation-related genes in skeletal muscle, including FABP and CPT1.

Impey SG et al. (2018)※3 proposed the “glycogen threshold hypothesis,” which holds that training in a low-glycogen state stimulates mitochondrial biogenesis via the AMPK pathway — further supporting the metabolic adaptation benefits of early morning fasted training.

When I say “unable to reach target VO2 max intensity,” I mean that you simply can’t push hard enough to hit the intensity required for effective high-intensity training. In other words, it becomes difficult to achieve a quality session.

While early morning training offers real advantages, the inability to reach target VO2 max intensity is a significant drawback. In my view, relying solely on early morning training creates a ceiling you simply can’t break through.

Why High-Intensity Training Matters

High-intensity training is essential for improving running performance.

If your only goal is to finish a full marathon, low-intensity jogging may be enough. But if you’re targeting a sub-3:30, sub-3:00, or faster, high-intensity training — particularly interval training — becomes critical.

The reasons are twofold: high-intensity training is more time-efficient, and some physiological adaptations can only be achieved at high intensities.

Here is how I define high-intensity training.

Training intensity is typically divided into five zones. High-intensity training corresponds to Zone 4 and above — specifically Zone 5 and higher.

Why Early Morning Training Makes High-Intensity Runs Harder

I define high-intensity training as exercise performed at 88% of max heart rate or higher (≥85% VO2 max).

One of the primary goals of high-intensity training is to improve VO2 max. It’s generally accepted that you need to reach at least 90% of max heart rate (≥88% VO2 max) to drive meaningful VO2 max gains.

Helgerud J et al. (2007)※4 compared four groups training at different intensities in an RCT. The group running at 90–95% max heart rate achieved the largest VO2 max increase — up to +13% — directly demonstrating the importance of this intensity threshold.

For runners whose training is primarily in the early morning, the barrier they hit is this: even when you’re trying to run hard, you can’t reach the oxygen uptake levels required for effective high-intensity training.

And even when you do manage to push to the target intensity, it feels significantly harder than it would at other times of day.

Here are the reasons I believe oxygen uptake is harder to raise in early morning training.

Right after waking, the parasympathetic nervous system is still dominant, making it difficult for heart rate to rise.

This isn’t just anecdotal — research backs it up. Chtourou H & Souissi N (2012)※5 conducted a comprehensive review of time-of-day effects on exercise performance and reported a clear circadian pattern: anaerobic performance is at its lowest in the early morning and peaks in the late afternoon or evening.

Yamanaka Y et al. (2015)※6 measured autonomic nervous system responses after morning and evening exercise. They found that morning exercise elevated parasympathetic activity during subsequent sleep (the HF component), while evening exercise increased sympathetic activity — confirming that the sympathetic nervous system is harder to activate in the morning.

A 2024 study (※7) found that after 12 weeks of aerobic training, only the evening exercise group showed significant improvements in sympathetic activity — the morning group showed no such improvement.

In winter, low temperatures cause vasoconstriction throughout the body, making it harder to deliver oxygen to working muscles.

Cortisol — specifically the cortisol awakening response (CAR) — peaks roughly 30–45 minutes after waking. Contrary to the common belief that cortisol “blocks glucose metabolism,” it actually promotes gluconeogenesis, releasing blood glucose from the liver.

While cortisol has been associated with reduced insulin sensitivity and increased muscle protein catabolism, clear evidence that the post-waking CAR directly impairs glucose utilization during high-intensity exercise is limited.

What we can say with confidence is that the low sympathetic activity immediately after waking impairs high-intensity performance. Zinman B et al. (1986)※8 demonstrated that catecholamines (including adrenaline) are essential for maintaining blood glucose during exercise — suggesting that if catecholamine output is insufficient right after waking, glucose mobilization may not keep up with the demands of high-intensity effort.

Taken together, these factors explain why early morning training and high-intensity training are a poor match.

When I attempt VO2 max training (targeting ~95% max heart rate) on cold winter mornings, my heart rate simply won’t climb — even at the same pace I’d run in the afternoon.

Yet despite the lower heart rate, the perceived effort is actually higher than it would be at midday. In cold conditions, the body burns extra energy through shivering and muscle tension to maintain core temperature — driving up oxygen consumption (VO2) even as heart rate stays suppressed.

Meanwhile, peripheral vasoconstriction keeps heart rate from rising. The result is a paradox: a low heart rate reading alongside a high actual physiological load — a dissociation noted by Doubt (1991)※9.

Claremont et al. (1975)※10 compared running at 0°C and 35°C and confirmed that oxygen consumption is higher in cold conditions. This is a critical reminder: if you’re using only a heart rate monitor to gauge intensity in the cold, your session will appear easier than it actually is.

How to Combine Early Morning Training with High-Intensity Workouts

That said, high-intensity training remains essential for improving your running. Even if nearly all your sessions happen before dawn, you still need to find a way to incorporate it.

Here are the specific strategies I’ve used to make high-intensity training work within an early morning schedule.

Build Consistency — Let Your Body Adapt

The more consistently you train early, the more your body adapts. Over time, you’ll find you can achieve high enough oxygen uptake to complete quality high-intensity sessions right after waking up.

With daily repetition, your circadian rhythm shifts, hormonal secretion patterns change, and the switch between parasympathetic and sympathetic nervous systems adapts. This isn’t speculation — it’s confirmed by research.

Chtourou H & Souissi N (2012)※5 reported that consistently training in the morning produces a “time-of-day-specific adaptation” — meaning morning performance progressively approaches the peak levels typically seen in the evening.

Facer-Childs ER et al. (2019)※11 showed that shifting the sleep phase forward by approximately two hours altered the timing of the cortisol awakening response and improved morning performance — directly supporting the idea that adjusting your circadian rhythm enhances early morning exercise capacity.

That said, no matter how well-adapted you become to morning training, pushing oxygen uptake in the depths of winter remains genuinely difficult. The effect of cold temperatures is simply too significant to overcome with adaptation alone.

Target Warmer Months for High-Intensity Sessions

If you can’t hit high-intensity targets on cold winter mornings, one option is to accept that winter isn’t the season for high-intensity training — and plan accordingly.

From December through February, shift the focus to low-intensity jogging, moderate runs, and light strides — skipping the hard sessions entirely.

From March through November, reintroduce high-intensity training aggressively.

By periodizing your training this way, you can sidestep the limitations of winter morning training altogether.

The complication, of course, is that many full marathons fall in February and March — which means December and January are exactly when you need high-intensity sessions.

Depending on your race calendar, this seasonal periodization approach may not always be feasible.

Schedule One Daytime High-Intensity Session Per Week

Another option is to reserve just one session per week for the daytime.

Work and family obligations make this difficult, I know — but even squeezing in a Saturday or Sunday afternoon run can make a meaningful difference.

In my own situation, this hasn’t always been possible. If you’re in the same boat, the strategies below — all doable before dawn — may be more practical.

Use Short Races as High-Intensity Training Substitutes

One highly effective strategy is to substitute short races for high-intensity training sessions.

Races of 10K or shorter provide enough intensity to count as a genuine high-intensity stimulus. Longer races create too much damage and compromise training continuity.

Racing also reduces perceived effort compared to solo hard efforts, allowing you to sustain a high pace for longer. As a result, races at distances from 3,000m to 10K — paces that push your VO2 max — become extremely effective training sessions.

Framing it as a “race” also tends to be easier to justify to family — which makes this one of the more accessible strategies for recreational runners.

Use Progression Runs to Reach Peak Effort

Even on cold mornings, structuring your run as a progression run — gradually increasing pace from start to finish — gives your body time to warm up. By the final portion of the session, you’re much more likely to reach the oxygen uptake levels needed for high-intensity adaptation.

Progression runs are well-established for marathon training. They effectively combine a warm-up and a high-intensity stimulus in a single, continuous effort.

The downside is that progression runs rely heavily on feel — for pacing and perceived effort — which means the training stimulus depends on the runner’s experience and intuition. This makes them better suited to intermediate and advanced runners.

If your goal is VO2 max improvement through a progression run, the final portion of the session needs to reach at least 90% of your max heart rate.

If you’re not yet at a level where you can accurately self-regulate by feel, use a heart rate monitor to confirm you’re hitting the required intensity.

Leveraging the Strengths of Morning Running

Early morning training may not be ideal for high-intensity work, but it offers genuine advantages that daytime runners don’t have.

By understanding the limitations and strategically compensating for them — while making the most of the unique benefits — you can improve your running performance efficiently.

In fact, a 12-week RCT by Shen B et al. (2025)※12 found that morning exercise (6–8 a.m.) outperformed evening exercise in reducing body fat and advancing sleep phase. Running in a fasted state in the early morning enhances fat metabolism (※1, ※2), and training in a low-glycogen state promotes mitochondrial adaptations (※3) — both of which are real advantages for dedicated morning runners.

Even Eliud Kipchoge, who trains in Kenya, is said to perform high-intensity sessions in the early morning.

At altitude, yes — but with temperatures above 10°C (50°F) and the ability to train in a group, his conditions allow for sufficient intensity even in the early hours. Those environmental factors matter.

Runners in cold Nordic countries are known to use treadmills extensively during winter. Even when snow or extreme cold makes high-intensity outdoor running impossible, understanding the underlying principles and adapting your approach dramatically increases the chances of effective training.

It’s precisely because recreational runners face so many constraints that understanding the principles behind performance gains matters most. Work with what you have — and make it count.

References

※1 Vieira AF, Costa RR, Macedo RCO et al. (2016) “Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis” British Journal of Nutrition

※2 De Bock K, Derave W, Eijnde BO et al. (2008) “Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake” Journal of Applied Physiology

※3 Impey SG, Hearris MA, Hammond KM et al. (2018) “Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis” Sports Medicine

※4 Helgerud J, Hoydal K, Wang E et al. (2007) “Aerobic high-intensity intervals improve VO2max more than moderate training” Medicine & Science in Sports & Exercise

※5 Chtourou H, Souissi N (2012) “The effect of training at a specific time of day: a review” Journal of Strength and Conditioning Research

※6 Yamanaka Y, Hashimoto S, Takasu NN et al. (2015) “Morning and evening physical exercise differentially regulate the autonomic nervous system during nocturnal sleep in humans” American Journal of Physiology

※7 (See PMID: 38377223) (2024) “Evening but not morning aerobic training improves sympathetic activity and baroreflex sensitivity in elderly patients with treated hypertension” The Journal of Physiology

※8 Zinman B, Murray FT, Vranic M et al. (1986) “Glucoregulation during exercise: hypoglycemia is prevented by redundant glucoregulatory systems, sympathochromaffin activation, and changes in islet hormone secretion” The Journal of Clinical Investigation

※9 Doubt TJ (1991) “Physiology of exercise in the cold” Sports Medicine

※10 Claremont AD, Nagle F, Reddan WD, Brooks GA (1975) “Comparison of metabolic, temperature, heart rate and ventilatory responses to exercise at extreme ambient temperatures (0C and 35C)” Medicine and Science in Sports

※11 Facer-Childs ER, Middleton B, Skene DJ, Bagshaw AP (2019) “Resetting the late timing of night owls has a positive impact on mental health and performance” Sleep Medicine

※12 Shen B, Zheng H, Liu H, Chen L, Yang G (2025) “Differential benefits of 12-week morning vs. evening aerobic exercise on sleep and cardiometabolic health: a randomized controlled trial” Scientific Reports