Overtraining Is a Hormonal Event – Here’s What Happens to T, Cortisol, and IGF-1 When You Don’t Recover

• Overtraining isn’t a training problem — it’s a hormonal problem. T drops, cortisol climbs, IGF-1 crashes, and the bloodwork change is measurable before you ever feel “overtrained.”
• The earliest reliable signal isn’t joint pain or performance decline. It’s HRV dropping consistently for 10 or more days. By the time a client feels overtrained, they’ve been hormonally suppressed for weeks.
• The HPA axis doesn’t distinguish between training stress and life stress. If you’re already running high cortisol from work, relationship strain, or poor sleep, the threshold for training-induced suppression is much lower than it looks on paper.
• Recovery deficit is cumulative. Two weeks of under-recovery doesn’t just pause your progress — it starts reversing it. The hormonal cost compounds in a direction you don’t want.
• The 6-12-25 Method structured at three days per week has been my primary tool for clients who’ve overtrained into suppression. The intensity is sufficient. The recovery window is the whole point.

Greg Massimino owns a CrossFit-style gym in Tampa. He’s 38, has been training five days a week for 18 consecutive years, and when he came to me his total T was 460 ng/dL — not clinically low, but low for a 38-year-old who lifts for a living, eats well, and doesn’t drink. His shoulder had been hurting for six months. He hadn’t had a genuine recovery day in longer than he could remember.

His first question was what supplement to add. My answer was that we needed to talk about what he needed to take away.

What Overtraining Actually Does to Your Hormones

Overtraining — technically called “overreaching” (a prolonged state of accumulated training stress that exceeds recovery capacity, distinct from normal short-term fatigue) when it becomes chronic — produces a specific and predictable hormonal signature. Understanding it makes the recovery strategy obvious.

The HPA axis (hypothalamic-pituitary-adrenal axis — the hormonal cascade that manages your stress response, releasing cortisol from the adrenal glands) responds to training stress the same way it responds to any other stressor: cortisol goes up. Short-term, post-training cortisol elevation is normal and appropriate — it’s part of the acute hormonal response that drives supercompensation. The problem is chronic elevation. When training load consistently exceeds recovery capacity, cortisol stops returning to baseline between sessions. It drifts up. And elevated cortisol competes with testosterone at the receptor level, directly suppresses the HPTA, and progressively blunts the GnRH signal that drives LH and testosterone production.

The IGF-1 side of this is less discussed but equally important. Growth hormone pulses — and therefore IGF-1 production from the liver — are heavily dependent on slow-wave sleep. When CNS fatigue accumulates from chronic overtraining, sleep architecture degrades: less deep sleep, more nighttime waking, worse recovery per hour of sleep. The result is reduced GH pulsatility during sleep, and IGF-1 tracks accordingly. Clients who have been overtraining for six months often have IGF-1 readings 30–50 points lower than their training age would predict, with sleep fragmentation as a primary driver.

Greg’s bloodwork when we started: T 460, IGF-1 142 ng/mL, morning cortisol 24.8 mcg/dL (elevated — normal morning cortisol is 10–20). His IGF-1 should have been closer to 180–200 for a man his age who trains as hard as he does. The gap between where he was and where he should have been was entirely explained by the cortisol pattern.

How the Cortisol-to-Testosterone Ratio Tells the Story

Single bloodwork snapshots don’t always catch overtraining early. The more useful signal is the cortisol-to-testosterone ratio tracked over time — not a single high cortisol reading, but a trend where cortisol climbs and T drifts down in parallel.

In functionally healthy men who train correctly, morning cortisol should run 10–18 mcg/dL and testosterone should be stable or improving over a training block. When I see morning cortisol consistently above 20 alongside declining T — even if T is technically “in range” — that pattern tells me the training load is outrunning the recovery capacity.

Nick Tashiro is the case I use to make this point. Nick is a 35-year-old accountant from Minneapolis who was training for an Ironman when he came to me. T was 290 ng/dL — genuinely low, not just suboptimal. His body fat was 9%. He was eating well, sleeping adequately, and in arguably the best cardiovascular shape of his life. The Ironman training was the problem.

High-volume endurance work produces prolonged cortisol elevation that compound-movement-focused strength training generally doesn’t. Ironman training in particular runs 15–25 hours of weekly training load, often without structured deload weeks. Nick’s cortisol-to-testosterone ratio, tracked over four months, showed a clear pattern: as training volume increased toward the race, T dropped. After I pulled up the trend with him, he acknowledged what he’d been ignoring — that he’d felt “flat” for three months and had written it off as race preparation stress.

Nick and I had an honest conversation about the Ironman. He wasn’t willing to pull out. I respected that and didn’t push. We completed the race, then ran four months of zero cardio — only compound strength training, three days per week. T climbed from 290 to 590 in that window. He now does triathlons at significantly reduced volume, and his T has held in the 600s. The T suppression wasn’t age or genetics — it was volume without recovery.

The CNS Fatigue Problem

CNS fatigue is the less-understood dimension of overtraining. Peripheral fatigue — muscle soreness, glycogen depletion, local inflammation — recovers in 24–72 hours for most people. Central nervous system fatigue from high-frequency, high-intensity training takes 5–10 days to clear. If you’re training intensely five or six days per week without ever giving the CNS a real recovery window, you accumulate a deficit that never clears.

The practical consequence: your 1RM drops, your working weight at 5RM drops, your bar speed drops — not from muscle weakness, but from impaired neural drive. Force production requires a motor neuron signal that a fatigued CNS can’t generate at full capacity. Clients who wonder why their compound lifts have been stagnant for three months despite consistent training are often experiencing CNS suppression, not a training problem that needs more training to fix.

Cameron Falk demonstrated this clearly without ever reaching clinical overtraining. Cameron is 25, an engineer in Phoenix, was training six days a week when he found me. His total T was 520, free T low end of normal, and he’d been stuck on the same working weights for four months despite training harder. He slept six hours a night and ate around 140 grams of protein at 195 lbs — under both for his training volume.

We cut his training to four days, pushed protein to 200g, and enforced 7.5+ hours of sleep. T hit 740 in 11 weeks. His strength numbers moved immediately once the CNS had a genuine recovery window — not because we changed his programming structure, but because we gave his nervous system time to actually regenerate between sessions. The additional recovery days were the training stimulus he needed.

The 6-12-25 Method as a Recovery-Compatible Intensity Protocol

One of the most common objections I hear from overtrained clients is that reducing training days means giving up intensity, which means giving up progress. This is wrong, but it’s a reasonable assumption if your mental model of training is “more sessions equals more stimulus.”

The 6-12-25 Method is my primary tool for addressing this objection. Three exercises per triset — six reps of a heavy compound movement, twelve reps of a moderate compound, twenty-five reps of an isolation finisher — performed with minimal rest between movements in the triset. The lactate accumulation from the 12-rep and 25-rep sets drives a significant acute GH response. The 6-rep set maintains strength stimulus and neural drive. Done correctly at three days per week, you’re generating a hormonal response from the training session that five-day programs at lower per-session intensity rarely match.

Greg fought me on this for three weeks before agreeing to try it. He was convinced that cutting to three training days would make him weaker and softer. What actually happened: his shoulder pain resolved in week two of the reduced frequency. His T climbed to 610 by month five — 150 points up from 460. His body composition improved despite training fewer days. By month six, Greg had restructured his clients’ programming to three days per week as well.

His words at the six-month mark were something close to: “I spent 18 years making this more complicated than it needed to be.” That’s the common thread across every overtraining case I’ve worked with. The solution is almost always less volume, better recovery, and higher per-session intensity — not the other way around.

How to Identify Overtraining Before the Bloodwork Catches It

Bloodwork runs quarterly at best for most people. You need early-warning signals that don’t require a lab. These are the ones I track with clients:

• HRV trend over 10+ days: A single low-HRV morning is noise. Ten consecutive low-HRV mornings is signal. If your wearable is showing a downward HRV trend of 10+ days and you haven’t been sick, overtraining is the first thing to rule out.
• Morning resting heart rate elevation: A resting HR 4–6 beats above your recent baseline for several consecutive days, without illness, is a CNS recovery signal.
• Motivation loss around training sessions: Most dedicated lifters don’t dread their workouts. When clients start finding reasons to shorten sessions or skip accessory work, it’s often CNS fatigue expressing itself as psychological resistance, not laziness.
• Strength plateau over 6+ weeks: Stagnant 5RM numbers despite consistent eating and training almost always indicate one of three things — insufficient protein, insufficient sleep, or insufficient recovery time between sessions.

The cortisol article covers the hormonal mechanism in more depth — specifically how chronic cortisol elevation from any source suppresses the HPTA. Training stress is one input. Work stress, poor sleep, and relationship strain are all inputs the HPA axis treats identically. If life is stressful, your training load threshold for hormonal suppression is lower than it would be otherwise. This is the part most training programs don’t account for and most clients don’t factor in.

The prescription, once overtraining has been identified, is not complicated: reduce training frequency to three days per week for a minimum of four weeks, enforce protein above 1g/lb bodyweight, enforce sleep above 7.5 hours. Add HRV monitoring if not already in place. Retest bloodwork at 8 weeks. The hormonal recovery is reliable if the recovery inputs are there. In my experience, T typically recovers 80–120 ng/dL within 8 weeks of a genuine recovery phase, and IGF-1 follows within 10–12 weeks.

The reason the three-day training week works isn’t philosophical — it’s mechanical. Supercompensation (the adaptation process where the body rebuilds stronger than baseline after a training stimulus — but only if recovery is sufficient) requires the recovery window to actually close before the next stimulus arrives. Three days per week allows that window to close. Five days per week, for most non-elite athletes, doesn’t.

Greg trained five days a week for 18 years and his T was 460. He switched to three days per week and his T hit 610 in five months. That data point is worth sitting with for a minute.