Exercise and the Adrenal Glands: Understanding the HPA Stress Axis—Cortisol Is Not Your Enemy but Your Training Partner

Opening: The Trainee Who Always “Tried Hard” but Got Slower

I once coached a trainee who left a deep impression on me—let’s call him A-Kai. He was 38, a tech-industry engineer, living in Hsinchu during the week and returning to Taipei on weekends. He was the type who would complete every workout on the plan and even secretly add extra volume. But for three months, his power output didn’t rise—it fell. His 20-minute test, which he could previously hold steadily at 220 watts, dropped to the point where 200 watts felt exhausting; his sleep became shallower, he woke up before his alarm, felt groggy in the afternoon, and felt nauseous whenever he rode up Wuling on weekends. The first thing he said when he came to me was: “Coach, am I not working hard enough? Should I add more training?”

I just asked him one question in return: “In the 30 minutes after you wake up, do you feel your energy gradually improving, or is your heart pounding while your mind feels blank?” He froze and said it was the latter. At that moment, I roughly knew the problem wasn’t a lack of effort—it was that his stress axis—the HPA axis—had been pushed to the point of losing its flexibility. This article is my attempt to explain to you, properly, the same framework I explained to A-Kai back then.

Many people frown the moment they hear “cortisol,” treating it as the enemy of fat loss, the culprit behind burnout, a “bad hormone” to be suppressed. But after years of coaching athletes and general fitness populations, I’m increasingly convinced of one thing: cortisol is not the enemy—it’s the key partner that determines whether you can get stronger from training. What actually harms you is never cortisol itself, but your failure to read it and your refusal to give it room to recover.

Conceptual Foundation: What Exactly Is the HPA Axis

A Relay Race of Three Organs

The HPA axis is the acronym for Hypothalamus—Pituitary—Adrenal, three structures often referred to in Chinese as the “hypothalamic-pituitary-adrenal axis.” You can think of it as the body’s command chain for handling “stress”:

1. The hypothalamus detects stress (which could be a high-intensity interval session, an exam, a sleepless night, or even a cold) and secretes CRH (corticotropin-releasing hormone).
2. CRH signals the pituitary gland, which releases ACTH (adrenocorticotropic hormone) into the bloodstream.
3. ACTH travels through the blood to the adrenal glands atop the kidneys, commanding them to secrete cortisol.

Once cortisol rises, it “feeds back” to tell the hypothalamus and pituitary: “Message received, you can stop now.” This is called negative feedback. A healthy HPA axis is like a responsive system that presses the accelerator when needed and the brake when needed. The problem is that when stress is chronic and unrelenting, and the brake is constantly pressed, this feedback mechanism becomes blunted—this is the core physiological issue behind overtraining and chronic stress.

What “Good Things” Cortisol Does During Exercise

Let me first defend cortisol. When you start a serious ride or run, the rise in cortisol is actually helping you:

• Mobilizing energy: Promoting glycogen breakdown and gluconeogenesis to raise blood glucose and fuel your muscles.
• Releasing fatty acids: Helping your body use more fat during prolonged exercise.
• Suppressing unnecessary inflammation and immune responses, concentrating resources on “finishing this workout right now.”
• Enhancing alertness and focus, helping you push through that final stretch of a steep climb.

Research generally observes that moderate-to-high-intensity exercise causes a transient rise in ACTH and cortisol, which typically returns to baseline within about an hour after exercise ends (see the EROS study and related reviews at the end of this article). The key words are “transient” and “comes back down.” A single workout raises cortisol, proper recovery brings it back down, and the body grows stronger through this rise and fall—this is what’s called “adaptation.” The acute rise in cortisol is part of the training stimulus, not a side effect. You could even say that without this surge, training couldn’t effectively tell the body “it’s time to get stronger”—it’s one link in the chain that translates stimulus into adaptation.

Cortisol’s Circadian Rhythm: Your Body Already Has a Curve

Here’s a crucial yet often overlooked concept: cortisol is supposed to be high and low, and it follows the day-night cycle.

In healthy people, cortisol is highest in the early morning, gradually declines through the day, and reaches its lowest point during deep sleep. Notably, about 30 to 45 minutes after waking, there’s a distinct peak called the Cortisol Awakening Response (CAR). In the literature, free cortisol rises by roughly 50% in healthy adults during those first 30 to 45 minutes after waking (studies report ranges from about 38% to over 150%), and roughly 70% or more of healthy adults show this typical curve (see the CAR review at the end of this article).

This awakening peak is the body’s way of “booting up”: raising blood sugar, boosting alertness, and preparing you for the day. Research also indicates that this awakening curve is regulated by the body’s internal circadian clock (the “master clock” in the brain’s suprachiasmatic nucleus) and by morning light exposure—in other words, regular routines and moderate morning sunlight are themselves ways of maintaining the rhythm of your stress axis (see the CAR-related studies at the end of this article). Conversely, chronic shift work, staying up late, and reversed day-night schedules directly disrupt this curve—another reason I pay special attention to my trainees’ sleep regularity.

The problem isn’t that cortisol is high in the morning; it’s when it fails to rise when it should, or fails to drop when it should. A-Kai’s issue was the latter—he didn’t feel gradually more alert in the morning; instead, his heart pounded while his mind felt blank, and at night he was tired yet couldn’t sleep deeply. This “flattened” or “squashed” rhythm often reflects HPA axis health better than any single number.

A Double-Edged Sword: Acutely Beneficial vs. Chronically Harmful

Separating acute from chronic is, in my view, the single most important thing to remember from this entire article. The same hormone, on different timescales, acts almost in opposite ways.

Aspect	Acute Elevation (during a single workout)	Chronic Elevation/Dysregulation (long-term stress accumulation)
Energy	Mobilizes glycogen and fat to fuel exercise	Continuously breaks down muscle protein; strength gains stall
Immunity	Temporarily suppresses inflammation, concentrates resources	Immune suppression; frequent colds, slow wound healing
Sleep	Returns to baseline after exercise; sleeps well at night	Fails to drop at night; difficulty falling asleep, early waking
Mood	Enhances focus and motivation	Irritability, low mood, loss of interest in training
Adaptation	Promotes supercompensation and getting stronger	Adaptation plateaus or even regresses
Recovery	Feels good and motivated the next day	Increasingly tired despite sleep; elevated morning heart rate

The keyword is comes back down. Acute elevation is beneficial because it returns to baseline; once the body is chronically in a state of “too much training, too little sleep, irregular meals from eating out, work stress, and commute fatigue” stacked on top of each other, cortisol’s rhythm flattens, negative feedback blunts, and you slide from “getting stronger after stimulus” to “getting weaker from depletion.”

Worth noting: chronic dysregulation doesn’t always manifest as “cortisol staying high.” In more severe, prolonged overtraining syndrome, research actually observes that these athletes show lower cortisol and ACTH responses to stress tests compared to healthy, active individuals (see the EROS-HPA study at the end of this article)—meaning the system has been pushed to the point where it “can’t be called into action” anymore. That’s why I never recommend that people self-diagnose based on a single blood cortisol reading—it’s far too easy to misread.

Cortisol and Testosterone: A Pair of Levers Pulling Against Each Other

To understand the difference between “getting stronger” and “getting drained,” we can also look at another hormonal tug-of-war. Cortisol leans toward catabolic processes—breaking down muscle protein and mobilizing energy; testosterone leans toward anabolic processes—repairing and building tissue. Training itself temporarily raises cortisol and diverts synthetic resources for immediate needs, which is normal; but during recovery, the balance needs to swing back toward the anabolic end for muscles to repair and grow stronger.

Sports science therefore often uses the “testosterone/cortisol ratio” as a rough indicator of whether the body is in an “anabolic-dominant (recovering well)” or “catabolic-dominant (accumulating fatigue)” state. I want to emphasize: this ratio varies between individuals, and blood draw timing has a major impact—it’s not something where a single reading determines your fate, and the general athletic population absolutely does not need to get frequent blood draws for this. But it gives us a very useful mental model: what you need to do is not “minimize” cortisol, but rather ensure there’s enough time for anabolism—meaning enough recovery. If there’s only breakdown and no repair over the long term, the balance gets stuck on the catabolic end, and that’s the real problem.

Why Chronically Elevated Levels Make You “Weaker Despite Training Harder”

Connecting the threads above, the pathway by which chronic cortisol dysregulation harms performance roughly goes: poorer sleep → nighttime cortisol doesn’t drop → tissue repair time is compressed → immunity is suppressed (easy to catch minor colds, slow wound healing) → inflammatory control becomes imbalanced → subjective fatigue rises, training motivation drops → the same intensity feels harder → you train more to “make up for it” → the stress account gets even more overdrawn. This is a self-reinforcing downward spiral, and it often creeps in quietly—by the time you notice “why am I getting slower despite training,” it’s often already been weeks. This is why I emphasize so strongly identifying signals early and proactively hitting the brakes, rather than waiting until you crash to deal with it.

Practical Methods: How to Structure Training and Recovery to Keep the Stress Axis Flexible

Principle One: Training Is “Stress,” Life Is Also “Stress”—They Share One Account

This is the concept I most want to instill in every athlete. Your HPA axis can’t tell whether the stress comes from 5 x 4-minute FTP intervals, an endless project deadline, or only 5 hours of sleep last night. They all draw from the same “stress account.”

So when A-Kai enters a work sprint phase and is working late every day, the first thing I do isn’t add more training—it’s cut training volume by 30%. Many people think this is “wasteful,” but during weeks when life stress is through the roof, forcing high-intensity sessions is just swiping a card on an account that’s already nearly maxed out.

Principle Two: Structure with Peaks and Valleys, Not Daily Moderate-High Intensity

The training pattern most damaging to the HPA axis isn’t “too heavy”—it’s “moderately heavy every day, never light enough and never hard enough.” This “grey zone” training gives your body a little stress every day but never gives it a full chance to drop back to baseline.

A healthier approach is polarization (make easy days truly easy, hard days truly hard), and ensure easy days are genuinely easy. Here’s a weekly example I give amateur cyclists (training about 6–8 hours per week); you can scale it to your own schedule:

Day	Session	Intensity Focus	Purpose
Monday	Rest or 20-minute walk	Very light	Let cortisol fully drop, clear fatigue
Tuesday	90-minute Zone 2 aerobic	Easy (conversational)	Build aerobic base, low stress
Wednesday	Intervals: 5×4 minutes near FTP	High	Main stimulus, spike acute cortisol
Thursday	60-minute Zone 2	Easy	Active recovery
Friday	Rest	Very light	Recovery
Saturday	3-hour long ride with some climbing	Low-moderate	Aerobic and endurance
Sunday	Intervals or group ride	Moderate-high	Second stimulus

The point isn’t this specific table—it’s the rhythm: hard days must be sandwiched between genuinely easy days or rest days. Aim for 2–3 high-intensity stimuli per week, and let the body decompress and supercompensate the rest of the time.

Principle Three: Schedule a Deload Week Every 3–5 Weeks

Even with good weekly planning, training stress still accumulates slowly. I typically have athletes progress for 3–4 consecutive weeks, then insert a deload week: cut training volume to 50–60% of normal, taper intensity as well, letting the HPA axis “reboot,” anabolic hormones replenish, and heart rate variability (HRV) recover.

Week	Training Volume (relative to normal)	High-Intensity Sessions	Feeling Goal
Week 1	100%	2–3	Slightly tired but manageable
Week 2	105–110%	3	Starting to feel accumulating fatigue
Week 3	110–115%	3	Clearly fatigued, looking forward to rest
Week 4 (Deload)	55–65%	1 (and not to failure)	Getting easier as the week goes, energy returning

The most common deload week mistake is “cutting volume but not wanting to cut intensity,” which leaves the body thinking it’s still grinding. The goal of a deload week is to make you feel like you’ve gotten stronger by the weekend and want to go all out—that restless eagerness is the signal that the HPA axis has regained its flexibility.

Principle Four: Sleep Is the Highest-Leverage Intervention

If you can only change one thing, change your sleep. Cortisol and sleep have a bidirectional relationship: elevated cortisol disrupts sleep, and poor sleep pushes cortisol higher, creating a vicious cycle (see the related review at the end of this article). This is why I rank sleep as the number one recovery priority, far above any supplement.

In practice, I ask athletes to: keep consistent bed and wake times (try not to vary too much even on weekends), avoid bright lights and phones for the hour before bed, and avoid doing high-intensity training too late (especially in Taiwan’s summer—finishing a ride drenched in sweat with elevated core body temperature makes it even harder to fall asleep).

Principle Five: Stabilize Blood Sugar with Nutrition and Fueling—Don’t Let “Hunger” Become Extra Stress

Many people overlook this: large swings in blood sugar are themselves a stressor that stimulates cortisol. Prolonged fasting, not taking in carbs during training, and delaying eating long after a session all put the body in an “energy deficit” alarm state, forcing the HPA axis to secrete more cortisol to rescue blood sugar. For someone trying to recover from training, this is shooting yourself in the foot.

Here’s a rough fueling timeline reference I give athletes. All values are ranges—adjust based on your body weight, intensity, and tolerance, and those with sensitive stomachs or chronic conditions (such as diabetes) should consult a physician or dietitian first:

Time Period	Goal	Rough Suggestion (Range)
1–3 hours before training	Top off glycogen, stabilize blood sugar	A carb-focused meal, avoid overly greasy or spicy foods that burden digestion
During training (if over ~90 minutes)	Maintain blood sugar, delay fading	About 30–60 grams of carbs per hour (more at higher intensity), with water and electrolytes
Within 1–2 hours after training	Replenish glycogen, kickstart repair	Carbs plus protein; common protein recommendation is about 20–40 grams per serving
Before bed	Avoid excessive nighttime hunger	If very hungry, a small snack—don’t go to bed starving, but don’t eat until stuffed either

The point isn’t obsessing over grams—it’s not letting the body stay in a state of “hunger” and “blood sugar chaos” for extended periods. Taiwan’s summers mean heavy sweating, so don’t forget electrolytes (especially sodium)—dehydration and electrolyte deficiency are also additional stressors.

Second Case: The Runner with “Great Data but Constantly Sick”

Let me share a different kind of case. Xiao-Ting was a dedicated recreational runner preparing for the Taipei Marathon. Her GPS watch data looked great, and her pace was steadily improving, but that season she caught a cold once a month and often complained, “I slept 7 hours but I’m still tired.” She initially thought she just had a weak immune system.

I asked her to lay out her daily routine, and the problem wasn’t training volume—it was the stacking and timing of stress: she habitually scheduled her hardest intervals on Wednesday nights, when she worked overtime the most, finished training at 11 PM, ate dinner afterward, went to bed around 12:30 AM after showering, and got up at 7 AM the next day. Training, sleep deprivation, late-night eating, and work stress were all crammed into the same day—like making four charges on the same overdrawn account. Her cortisol rhythm was disrupted by this arrangement, failing to drop at night—her immunity was chronically suppressed, making her naturally prone to getting sick.

We made only three adjustments: moved the hard workout from Wednesday night to Saturday morning (when her stress was lower on weekends), made sure she ate carbs and protein soon after training instead of delaying it until late at night, and pushed her bedtime earlier. Total training volume didn’t change—we just redistributed the timing of stress and added recovery. A little over a month later, she didn’t get sick for the rest of that season, her subjective fatigue dropped, and she finished the race successfully. This is the case I especially want you to remember: sometimes the problem isn’t “training too much,” but stress all piled together with no room left for recovery.

Taiwan-Specific Context: Climate, Eating Out, and Healthcare

These are the points I specifically emphasize when coaching athletes in Taiwan:

• Summer heat and humidity: Taiwan’s summers are hot and muggy, and the physiological stress (including the HPA response) during high-intensity training is greater. I recommend moving hard sessions to early morning or evening, avoiding midday; for long rides, be sure to hydrate and replace electrolytes—dehydration itself is an additional stressor.
• Eating out and irregular routines: Eating out in Taiwan is convenient but often means high oil, heavy salt, and refined carbs, plus busy work schedules that lead to “skipping meals here and there.” Big swings in blood sugar can also stimulate cortisol. I usually recommend fixed meal times, protein and vegetables at every meal, and getting carbs and protein within 1 to 2 hours after training—don’t keep your body in a constant state of “hunger” stress.
• Commuting and prolonged sitting: The Hsinchu–Taipei commuters and long-hour engineers are the highest-risk group for HPA dysregulation I’ve seen. These people need to be even more disciplined about leaving “blank space” for training.
• Healthcare access: Taiwan’s National Health Insurance makes seeing a doctor easy. If you have long-term fatigue, serious sleep disturbances, unexplained weight changes, or persistent low mood, don’t self-diagnose adrenal-related diseases online—see a physician for evaluation. Many symptoms overlap with thyroid issues, anemia, depression, sleep apnea, and more, and need professional differential diagnosis. Don’t draw your own conclusions or buy medications or supplements on your own.

Common Mistakes and Corrections

Mistake 1: Treating “being exhausted” as “getting a good workout” and “easy” as “slacking off”

Many hardworking people (like A-Kai) carry a moral burden: if they don’t finish a session feeling wrecked, it feels worthless. But adaptation happens during recovery, not during the workout itself. The fix: schedule rest days and deload weeks into your plan and treat them as “required training sessions,” not optional blank space.

Mistake 2: Living in the “gray zone” long-term

Every ride is neither here nor there—a bit breathless but never truly pushing. The fix: on easy days, wear a heart rate monitor or watch power, and force yourself to go genuinely easy (able to hold a smooth conversation); on hard days, actually go hard. Widen the gap between high and low.

Mistake 3: Scaring yourself with a single number

Panicking over one blood test showing elevated cortisol, or buying up “cortisol-lowering” supplements. The fix: cortisol has circadian fluctuations and is heavily influenced by the time of blood draw and current stress levels—a single point is of limited value. Instead of staring at numbers, observe trends and function—morning energy, sleep quality, resting heart rate, HRV, and training motivation.

Mistake 4: Pushing through with caffeine and sleep deprivation

Chugging coffee when fatigued and sacrificing sleep to fit in training. The fix: caffeine prolongs cortisol clearance and can interfere with sleep; when you’re already running on empty, this is pouring fuel on the fire. When you’re tired, sleeping is often more productive than squeezing in another session.

Mistake 5: Ignoring “non-training stress”

Managing only the workout plan while ignoring work, family, and emotional stress. The fix: remember the “shared account” analogy. In high-stress phases of life, proactively dialing back training isn’t regression—it’s smart.

Self-Observation: Signals You Can Track Without Blood Tests

I often ask athletes to spend 30 seconds each morning rating a few items on a 1-to-5 scale, building a trend over time:

Observation Item	Good (Recovered)	Warning Sign (Possibly Overloaded)
Morning energy	Gradually alert and energetic after waking	Racing heart, foggy head, forcing yourself out of bed
Sleep	Falls asleep easily, few night awakenings	Difficulty falling asleep, waking up too early
Resting heart rate	Stable or on the low side	Elevated for several consecutive days
Training motivation	Want to move, look forward to sessions	Resistant, can’t muster the energy
Mood	Steady	Irritable, low
Performance	Same intensity feels easier	Same intensity feels harder

A single day isn’t reliable—the key is the trend over 3 to 5 consecutive days. If multiple items flash warning signs at once, your body is asking you to hit the brakes. A-Kai later used this exact table to learn how to reduce his volume on his own before things fell apart.

The Three Stages of Fatigue: Not All Fatigue Is the Same

In sports science, training-induced fatigue is often categorized into several levels. Understanding this spectrum helps you judge “should I push or back off right now”:

Stage	Plain-Language Explanation	Recovery Required	What to Do
Functional Overreaching	The brief dip after deliberately stacking several hard days—part of the training process	A few days to about a week	Follow the plan and deload; a rebound in performance usually follows
Non-Functional Overreaching	Fatigue piled on too heavily; performance stalls and condition worsens	Several weeks	Significantly reduce volume, fill up recovery, stop pushing
Overtraining Syndrome	Long-term HPA dysregulation; performance, mood, and systems decline across the board	Several months	Substantial rest, and see a doctor to rule out other issues

The key message here: a short-term dip (Stage 1) is normal and useful. It typically appears after a deliberately intensified training block, and as long as you deload properly afterward, it often yields a wave of progress. The real trouble is when you don’t notice it and keep pushing, sliding from Stage 1 into Stages 2 and 3. The further right you go, the higher the time cost of recovery—from days, to weeks, to months. So “backing off a little earlier” is almost always cheaper than “crashing a little later.” The EROS research mentioned earlier also reminds us that by the time you reach overtraining syndrome, the HPA axis becomes blunted in its response to stress—this state can’t be fixed with one good night’s sleep.

A Simple “Total Stress Load” Self-Checklist

Before planning the next week’s training, I often ask athletes to spend one minute asking themselves these five questions. If any answer is “not great,” reduce the intensity or volume for the week:

• How is work/family stress this week? (High → reduce volume)
• How many hours did you sleep on average over the past few nights, and how deep was it? (Poor → reduce volume)
• Do you wake up feeling fresh, or is your heart pounding? (The latter → reduce volume)
• Any scratchy throat or feeling like you’re coming down with something lately? (Yes → reduce volume)
• Thinking about today’s session—are you looking forward to it or dreading it? (Dreading → reduce volume)

These five questions require no equipment or blood tests, yet they help you place “training stress” back into the context of “total life stress.” This is the most practical daily practice for managing the HPA axis.

Actionable Advice for Readers at Different Levels

Beginners (less than one year of regular exercise)

• Prioritize consistency first: a fixed routine and fixed training times matter more than a fancy workout plan.
• One to two high-intensity sessions per week is more than enough; the rest should be easy aerobic work.
• Don’t chase daily tangible fatigue—learn to distinguish between “good tired” and “wrong tired.”
• Getting enough sleep is the fastest shortcut to progress at this stage.

Advanced Athletes (clear goals, 6+ hours of training per week)

• Introduce polarized training and deload weeks; proactively deload every 3 to 5 weeks.
• Start tracking HRV and resting heart rate trends, but treat them as tools, not masters.
• Proactively reduce volume during high-life-stress periods; keep the “shared account” in mind.
• Pay special attention around race season: the event itself is a massive stressor—give yourself ample recovery afterward.

People Who May Already Be Overtrained

• Rest genuinely first: schedule a significant reduction in training for several consecutive days up to one to two weeks. Don’t rush to “adjust the training plan.”
• Get sleep and nutrition fully dialed in.
• If symptoms persist for more than a few weeks, or are accompanied by significant sleep disorders, mood issues, or abnormal weight, seek medical attention to rule out other conditions.
• Don’t buy supplements claiming to “regulate the adrenal glands” as a solution on your own.

Frequently Asked Questions (FAQ)

Q: If my cortisol is high in the morning, does that mean I shouldn’t train in the morning?
A: No. The natural rise in morning cortisol is a normal awakening response, and most people have no problem training in the morning. The key is overall recovery, not avoiding a specific time of day.

Q: So, is “adrenal fatigue” real?
A: “Adrenal fatigue” is not a formal diagnosis in mainstream medicine. The fatigue you feel is real, but it’s more likely the combined result of training overload, insufficient sleep, nutrition, or other medical issues, rather than something as simple as your adrenal glands being “worn out.” Instead of labeling it, it’s better to address the total stress load behind it and consult a doctor for clarity.

Q: Do I need to get my cortisol tested?
A: For the general athletic population, daily self-observation (sleep, morning state, heart rate, training motivation) is usually more useful than a one-time blood test. If there are specific medical concerns, the decision to test and interpret the results should be made by a physician.

Q: Can supplements “lower cortisol”?
A: Many products on the market make this claim, but their effectiveness and safety vary, and they may mask the real problem. Getting sleep, nutrition, and training rhythm right is far more practical than supplements. If needed, consult a doctor or nutritionist.

Q: Will fasted training (training in the morning without eating) cause cortisol to get too high and be counterproductive?
A: Short-duration, low-to-moderate intensity fasted cardio is feasible for most healthy people, and a small rise in cortisol is within the normal range. But if you’re doing long-duration or high-intensity training fasted, insufficient energy can amplify the stress response and slow recovery. The principle is: the higher the intensity and the longer the duration, the more you should consume some carbohydrates beforehand. Those with blood sugar-related conditions should consult a doctor first.

Q: If my HRV (Heart Rate Variability) drops, does that mean my cortisol is too high and I need to rest?
A: HRV is a window into your autonomic nervous system and overall stress state. A downward trend is often associated with accumulated fatigue, poor sleep, or early signs of illness, and is worth paying attention to. However, it can be influenced by alcohol, sleep, and measurement timing, and a single day’s reading isn’t reliable. Treat it as a trend tool, use it alongside your morning self-assessment, and don’t let one number dictate your training emotions.

Q: Is moderate stress actually good for the body?
A: Yes, this is the key point. Training makes you stronger precisely because it is a form of “recoverable stress”—the body is stimulated, and then supercompensates during recovery. What we should avoid is never stress itself, but rather total stress exceeding recovery capacity for too long. Learn to pair stress with adequate recovery, and you turn stress into fuel for progress.

Q: So, should I spend money on cortisol testing or stress hormone panels?
A: For the vast majority of general athletes aiming for health and performance, my answer is “not for now.” Daily signals like sleep, morning state, resting heart rate, and training motivation—free and immediate—often guide your next step better than one expensive test. If you have specific medical symptoms, it’s more reliable to let your doctor decide what tests are needed and how to interpret them.

Conclusion: Learn to Work with Cortisol, Not Against It

Back to A-Kai. We didn’t give him any magic supplements, nor did we add more training. All we did was: cut volume by 30%, make easy days truly easy, deload every fourth week, prioritize sleep above all, and proactively scale back during work crunch periods. After about six weeks, his mornings started to feel “gradually better” instead of “heart pounding,” and his 20-minute power slowly climbed back, even surpassing previous levels. He later told me, “So getting stronger is about knowing how to rest.” I was very pleased to hear that, because it meant he truly internalized the concept, not just followed the training plan mechanically.

This is the one takeaway I most want to leave you with. Cortisol is not an enemy to be eliminated, and the HPA axis is not a system that gets better the more you push it. It’s a mechanism that requires balance between tension and release—give it stimulus when it’s time to press the gas, and give it recovery when it’s time to hit the brakes. The better you learn to work with it, the more it will convert every bit of your effort into real progress.

Finally, let me share an image I often use with my athletes: think of a week as one breath. A hard workout is the “inhale”—you apply stress and raise cortisol; a recovery day is the “exhale”—letting it drop and allowing anabolism to take over. Inhaling without exhaling leads to oxygen debt; exhaling without inhaling provides no stimulus. Those who know how to breathe go the distance. The art of training, in the end, is mastering this rhythm of inhale and exhale.

Read your stress axis, and take good care of it. Your body will repay you with better performance and a fresher feeling every morning.

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This article is for educational purposes and does not replace individual diagnosis and treatment advice from a physician, physical therapist, or nutritionist. If you have a chronic condition (such as diabetes, hypertension, heart disease) or long-term fatigue, sleep issues, or emotional distress, please seek medical attention for individualized assessment from a professional.

References

• Hypothalamic-Pituitary-Adrenal (HPA) Axis Functioning in Overtraining Syndrome (EROS-HPA Axis), PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC5722782/
• Exercise and the Cortisol Awakening Response: A Systematic Review, PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC5635140/
• Cortisol Awakening Response: Regulation and Functional Significance, Endocrine Reviews (Oxford Academic): https://academic.oup.com/edrv/article/46/1/43/7739741
• Endocrine responses of the stress system to different types of exercise, Springer: https://link.springer.com/article/10.1007/s11154-022-09758-1
• Physical activity and cortisol regulation: A meta-analysis: https://midus.wisc.edu/findings/pdfs/2669.pdf

Related Reading

• Pre-Race Stress Hormone Cortisol: Peak Times and 5 Evidence-Based Tips for Downregulation
• Swimming and Stress Hormones: Balancing Training Load and Cortisol
• A Complete Guide to Exercise and Hormones: Testosterone, Cortisol, and Growth Hormone—Understanding Your Endocrine Signals
• Hormonal Responses to Running: Cortisol, Testosterone, and Training Adaptations