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Sarcopenia Coaching Protocol

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Sarcopenia Coaching Protocol

TL;DR

A three-tier coaching system maps biometric and wearable signals to action levels: Green (monitor) for stable trends, Yellow (check-in) for concerning trajectories, and Red (refer) for clinical referral. The protocol is designed for users on or considering GLP-1 therapy, with specific attention to BIA ALM trends, grip strength trajectories, iPhone gait speed, HRV trends, and protein intake. DXA referral is the key clinical action triggered by Tier 3.

Tier 1 — Green (Monitor)

Maintain current coaching and monitoring cadence.

Criteria:

  • HRV within 20% of 90-day rolling baseline
  • iPhone gait speed ≥1.0 m/s
  • Grip strength >30 kg (male); >20 kg (female)
  • BIA ALM stable or improving (monthly trend)
  • Protein intake ≥1.6 g/kg/day
  • Resistance training ≥3 sessions/week
  • No unexplained functional decline

Action: Continue standard coaching cadence. Reinforce resistance training and protein intake as the anchors.

Tier 2 — Yellow (Check-in)

Review protein intake, training consistency, sleep quality, and recent trajectory. No clinical referral yet.

Criteria:

  • HRV drops 20–30% from baseline for 2+ weeks (combined with other yellow flags)
  • iPhone gait speed 0.8–0.9 m/s
  • Grip strength 27–30 kg (male approaching EWGSOP2 threshold) / 16–20 kg (female)
  • Grip strength drops >10% from 90-day personal baseline
  • BIA ALM decline 3–5% in 30 days during GLP-1 therapy
  • Protein intake <1.4 g/kg/day
  • Exercise sessions drop >20% from baseline

Action:

  • Vitals check-in: review protein intake, training consistency, sleep quality
  • Reinforce resistance training ≥3×/week
  • Reinforce protein 2.0–2.5 g/kg/day
  • If on GLP-1: review whether dose is appropriate relative to nutrition
  • Recheck BIA ALM in 30 days; if continued decline → escalate to DXA consideration

Tier 3 — Red (Refer)

Recommend clinical evaluation for body composition and functional assessment.

Criteria:

  • HRV drops >30% from baseline sustained 3+ weeks (combined with functional decline)
  • iPhone gait speed ≤0.8 m/s (EWGSOP2 low physical performance criterion)
  • Grip strength <27 kg (men) / <16 kg (women) — EWGSOP2 probable sarcopenia
  • BIA ALM loss >5% in 30 days during GLP-1 therapy
  • Unexplained falls or functional decline
  • BIA ALM approaches <20 kg (men) / <15 kg (women)

Action:

  • Recommend DXA for definitive body composition assessment
  • Recommend clinical grip strength evaluation (Jamar dynamometer)
  • Consider endocrinology or geriatric referral
  • Review GLP-1 therapy risks vs. benefits in context of muscle health trajectory

DXA Referral Triggers

TriggerRationale
Baseline before or early in GLP-1 therapyReference point for all future body composition interpretation
BIA ALM within 10% of EWGSOP2 cut-offsDXA needed to confirm or rule out confirmed sarcopenia
Tier 2 coaching alerts fire for 2+ consecutive monthsAccumulating evidence of concerning trajectory
BIA ALM loss >5% in 30 days during GLP-1 therapyExceeds alarm threshold; DXA needed to quantify
Every 12 months for high-risk individuals (≥65, CKD, frailty)Standard surveillance for highest-risk group
Every 6 months if prior lean mass loss detected on GLP-1 therapyActive monitoring during catabolic therapy

Note on DXA frequency: LSC is 3.85–19.4% — scanning less than every 3 months is unlikely to detect clinically meaningful individual change reliably. DXA is for baselines and Tier 3 referral, not frequent monitoring.

Practical Coaching Priorities

The following are the most actionable coaching levers, in order of evidence strength:

1. Resistance training (strongest evidence)

  • ≥3 sessions/week, major muscle groups, progressive overload
  • The anchor intervention — the only thing with consistent evidence reducing lean fraction during GLP-1 therapy
  • Resistance training + lifestyle reduces lean fraction to ~17.5% vs. ~26% with either alone

2. Protein intake

  • Target: 2.0–2.5 g/kg/day during GLP-1 therapy
  • Minimum: ≥1.2 g/kg/day
  • Split across meals: 30–40 g per meal for maximal MPS (muscle protein synthesis) stimulation
  • Appetite suppression from GLP-1 makes this non-intuitive — users need explicit guidance

3. Biomarker monitoring

  • Cystatin C every 3 months (calculate Sarcopenia Index trend)
  • IGF-1 every 6 months (morning fasting draw only)
  • Creatinine as standard GLP-1 monitoring but do not use alone for muscle inference

4. DEXA timing

  • Baseline before or early in therapy (not for frequent monitoring)
  • Triggered by BIA trajectory or clinical thresholds (see above)

Common Coaching Errors to Avoid

ErrorCorrection
Using scale weight alone to track progressAlways interpret weight in body composition context; BIA trend + grip strength trend
Using consumer foot-to-foot BIA for individual trackingErrors up to ~10 kg; use Withings Body Scan minimum
Measuring IGF-1 in afternoonDiurnal variation ~30%; only morning fasting draws are comparable
Stopping GLP-1 without a muscle preservation planWeight re-gain post-cessation is common; lean mass trajectory matters
Waiting for symptoms before acting on biomarker trendsBiomarker trajectories should trigger coaching before functional symptoms appear
Using Apple Watch for grip strength or muscle massNo validated sensor exists for either

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