Bone Stress Injury + Recovery Risk Screening
How to use
- Tick all that apply over the last 2–4 weeks
- Higher score = higher risk of impaired bone health and stress injury risk
- Focus is not bodyweight alone, but fuel + training mismatch
SECTION 1: ENERGY AVAILABILITY WARNING SIGNS
These reflect RED-S low energy availability (LEA)
- Frequent training but “not eating much more than usual”
- Skipping breakfast or post-training meals ≥3 times per week
- Long gaps (>5 hours) between meals on training/work days
- Regular calorie restriction while maintaining or increasing training
- Feeling “fine” during training but crashing later in the day
- Unintentional weight loss or difficulty maintaining weight
- Persistent fatigue not explained by sleep
Why it matters (science link)
Low energy availability reduces bone formation marker (P1NP ↓ ~14%) and increases bone resorption (CTX ↑ ~30%) during exercise exposure (Fensham et al., 2022).
SECTION 2: CARBOHYDRATE LOW AVAILABILITY SIGNS (HIGH IMPACT FOR BONE)
These are particularly important because low carbohydrate was shown to suppress bone formation more than energy restriction alone.
- Training in a fasted state more than 2x/week
- Regular low-carb dieting while doing resistance or endurance training
- Avoiding carbs around training sessions “to stay lean”
- Feeling flat, slow, or underpowered in workouts
- Poor recovery between sessions despite adequate protein intake
- Cravings for sugar or carbs in the evening after training
Why it matters
Low carbohydrate availability:
- ↓ P1NP (bone formation) up to ~26%
- ↓ osteocalcin up to ~40%
- ↑ exercise-related CTX response (bone breakdown signal)
(Carbohydrate restriction has a stronger negative effect on bone formation than low energy alone in short-term controlled studies.)
SECTION 3: TRAINING LOAD + STRESS OVERLAP
Bone stress injuries are driven by mechanical load + poor recovery capacity
- Increasing training volume or intensity without increasing food intake
- 3+ high-impact training days per week (running, jumping, heavy lifting)
- Repeated sessions without full recovery days
- “Double stress days” (hard workout + long workday + low food intake)
- Pain in shins, feet, hips, or lower back that worsens with impact
Why it matters
Exercise increases bone turnover (both CTX and P1NP), but without adequate carbohydrate/energy:
- bone formation does not keep up
- net balance becomes negative over time
SECTION 4: EARLY BONE STRESS WARNING SIGNS
These may indicate early stress injury development
- Localised bone pain (not muscle soreness)
- Pain that starts during exercise and lingers after
- Pain that becomes more specific over time (pinpoint location)
- Pain when hopping, running, or loading a limb
- Morning stiffness in a specific bone region
- Pain that improves with rest but returns with impact
SECTION 5: RECOVERY AND ADAPTATION SIGNALS
These reflect whether bone is recovering properly
- Persistent soreness >48 hours after training
- Declining performance despite consistent training
- Poor sleep quality during heavy training weeks
- Feeling “wired but tired”
- Increased resting heart rate or perceived effort
- Frequent minor niggles accumulating over time
SECTION 6: WORK + LIFESTYLE ENERGY DRAIN (OFTEN IGNORED)
Important in gym populations with jobs
- Physically active job + training on same day
- Long work shifts without planned meals/snacks
- High cognitive stress days combined with training
- Reliance on caffeine instead of food during workdays
- “I forget to eat when busy” pattern
Why it matters
Work stress + training stress reduces effective energy availability even if calorie intake looks “normal”.
SCORING SYSTEM (SIMPLE RISK STRATIFICATION)
LOW RISK (0–3 ticks)
- Adequate fueling pattern
- Stable recovery
- Low likelihood of bone stress imbalance
MODERATE RISK (4–7 ticks)
- Likely intermittent low energy availability
- Possible reduced bone formation response
- Early warning zone for RED-S drift
Action:
- Add structured carbohydrate around training
- Avoid fasted training
- Ensure regular meals every 3–4 hours
HIGH RISK (8+ ticks)
- Strong indication of RED-S physiology pattern
- High risk of impaired bone remodelling balance
- Increased risk of bone stress injury
Action:
- Immediate increase in energy + carbohydrate availability
- Remove low-carb training periods
- Fuel every training session and work block
- Consider professional sports dietitian or clinician review
SIMPLE INTERVENTION RULES (BASED ON THE SCIENCE)
Rule 1: Carbs protect bone during training
Feeding before exercise reduces bone resorption response (CTX reduction up to ~30–50%)
Rule 2: Low carbohydrate is a bone formation suppressor
Short-term low carb exposure reduces:
- P1NP (bone formation)
- osteocalcin (bone turnover regulation)
Rule 3: Energy + carbohydrate mismatch is the real risk
Not just “not eating enough”, but:
training hard + low carbohydrate availability = worst bone scenario
Rule 4: Bone stress injuries are cumulative
Each day of low fuel + high load = small negative bone balance that accumulates over weeks
PRACTICAL TAKEAWAY FOR GYM USERS
Bone stress injuries are rarely caused by one workout. They are caused by repeated training with insufficient carbohydrate and energy to support bone rebuilding.
