Identifying Red Flags

An injury doesn't appear overnight.

It builds. Slowly. Quietly. Usually while you're ignoring the warning signs.

You feel a twinge. You think, "It's nothing, just a little soreness." You keep training.

Two weeks later, the twinge becomes a persistent ache. You think, "Hmm, I should probably address this." You keep training.

Four weeks later, you can't run at your target pace. You think, "Okay, this is a real problem." You finally see someone.

By then, you've lost 6 weeks to deconditioning because you didn't address it when it was a twinge.

Learning to identify red flags—the early warning signs of injury—is how you stay healthy through 170 kilometers of training.

Cardiovascular and Structural Red Flags

There are two categories of red flags: ones that signal overtraining or inadequate recovery, and ones that signal structural problems.

Overtraining Red Flags:

These are signs that your nervous system is fried, your recovery is insufficient, or your training load is too high:

Elevated resting heart rate: Your baseline RHR is 58 bpm. If it climbs to 64+ bpm consistently over 3+ days (not just one elevated morning), this signals overtraining.
Crashed HRV: Your baseline HRV is 39. If it drops below 30 for consecutive days, your nervous system is stressed.
Persistent fatigue: You feel tired even after rest days. Your legs feel heavy. Your motivation is gone.
Elevated morning heart rate after hard workouts: After a tempo run, your morning HR should return to baseline within 24 hours. If it's still elevated on the second day, you didn't recover.
Elevated resting heart rate during runs: Your heart rate during easy runs is creeping up. What used to be 145 bpm now requires 155 bpm to maintain the same pace. This signals fatigue accumulation.
Sleep disruption: You're lying awake. You're waking up frequently. You're not sleeping deeply even though you have 8 hours in bed.
Mood changes: You're irritable. You're anxious. You're having trouble concentrating.

When I see 3+ of these signs simultaneously, I immediately reduce training intensity (not volume) and prioritize sleep and recovery.

Structural Red Flags:

These are warning signs that something is biomechanically wrong and injury is developing:

Pain that appears in the same spot consistently: Sharp pain in your left knee on descents, aching in your right shin on long runs—these are structural problems, not just soreness.
Pain that gets worse over the course of a run: You feel fine at kilometer 10, but by kilometer 25 the pain is significant. This suggests a mechanical problem that accumulates with volume.
Asymmetrical pain: One leg hurts, the other doesn't. This suggests either an injury on that side or a compensation pattern.
Pain that doesn't improve within 2 weeks of rest: Normal training soreness should resolve with 2–3 days of reduced intensity. If it persists beyond 2 weeks, it's structural.
Swelling or visible inflammation: Puffiness around your ankle, knee, or hip. Warmth in the joint. Visible bruising.
Altered running gait: You're limping slightly. You're shifting weight to one side. You're shortening stride on one leg.
Pain that wakes you at night: Sleep is usually when inflammation decreases. If pain wakes you, the inflammation is significant.

For me, the most relevant red flag is right plantar fasciitis. I experienced this after the BDG Ultra 64K in 2024, when I ran macadam downhills. The repetitive impact on descent caused heel pain.

My approach to this vulnerability:

When I feel even mild heel pain, I:

Reduce impact volume (fewer long runs on hard surfaces)
Focus on technical trail running (softer landings, better technique)
Do calf stretches and plantar fascia release work
Ice if needed

When I see structural red flags, I immediately:

Stop running if pain is sharp or worsening
Reduce volume if pain is stable but present
Get professional assessment if pain persists beyond 2 weeks
Follow rehab protocol precisely

I don't ignore it. I don't "run through it." I acknowledge it and adapt my training.

Composition Metrics: Monitoring Long-Term Physical Adaptations

Your body composition tells a story about your training and recovery.

I used to track body composition almost daily using a Xiaomi Body Composition Scale 2, which gave me measurements of body weight, muscle mass, fat percentage, water percentage, and bone mass.

This was valuable data. I could see patterns:

Normal fluctuation: ±1-2 kg based on hydration, glycogen, sleep
Red flag: Consistent weight gain of 2+ kg over 2+ weeks despite good training
Interpretation: Either you're gaining muscle (good during base phase) or retaining water (sign of overtraining/inflammation)

In August 2025, when my work crisis hit, I would have seen my weight retention increase as my stress hormone cortisol spiked. This would have confirmed what my HRV was already telling me: I was in overtraining territory.

Unfortunately, my scale broke, and I haven't replaced it yet. But this is a valuable monitoring tool if you have access to it.

What to monitor if you have a body composition scale:

Weight stability: ±1-2 kg fluctuation is normal; consistent gains over 2+ weeks suggest water retention
Muscle mass trends: During high-volume training, muscle mass should stay stable; loss suggests underfueling
Fat percentage: Minor fluctuations are normal; consistent loss during high-volume training is normal; gains suggest underfueling or overtraining

What to monitor if you don't have a scale:

How your clothes fit: Your best indicator of composition changes
Energy levels: Loss of energy despite adequate sleep suggests underfueling
Visual appearance in the mirror: Noticeable muscle loss or bloating suggests composition changes

These metrics rarely change week-to-week. But month-to-month, they reveal whether your training is building or breaking you down.

Movement Screening: Identifying Dysfunction Before It Becomes Injury

I haven't done a quarterly movement screening with a strength coach yet. This is something I should do but haven't prioritized.

However, I know what a good movement screening would assess:

Single-leg squat (assesses hip stability, knee alignment, ankle mobility)
Single-leg hop (assesses power, stability, confidence)
Lateral band walk (assesses glute activation)
Step-down test (assesses hip control and knee tracking)
Lying hip abduction (assesses glute strength)
Prone push-up position (assesses core stability)
Crawling patterns (assesses movement quality and asymmetries)

From these tests, a good coach can identify:

Which muscles are weak
Which joints are unstable
Which patterns are compensating for weakness
Which asymmetries exist between left and right

Why I haven't done this yet:

I've been focused on volume training for my three 100K races in 2025 rather than investing time in formal assessments. This was partly a trade-off—given limited time, I prioritized race experience over testing.

But for my 170K training in 2026, I'm planning to do this. It would give me objective data about whether my strength training (which I've been inconsistent with) is actually building balanced strength.

How to get a movement screening:

Ask your local running club for recommendations
Look for strength coaches with "running" or "endurance" in their specialty
Ask a physical therapist (many offer screening services)
Cost: typically $80–150 per session

It's an investment, but it's much cheaper than dealing with a 6-week injury due to a movement dysfunction you didn't know about.

Anggriawan Sugianto