The physiology of endurance performance changes meaningfully after 40 — and the nutritional strategy that supported training at 28 may need significant revision to remain effective at 48. The most consequential age-related changes from a nutrition perspective are: reduced anabolic sensitivity to protein (requiring higher protein doses to achieve equivalent muscle protein synthesis); declining bone density (requiring strategic calcium, vitamin D, and collagen support); slower glycogen resynthesis rates after exercise; and reduced recovery capacity that compresses the window between productive training sessions. None of these changes are inevitable performance limiters — they are adaptable realities that respond to specific nutritional interventions.
Masters athletes face a paradox: the populations with the most to gain from evidence-based sports nutrition are often the least represented in sports nutrition research, which overwhelmingly studies athletes aged 18–30. Applying findings directly is not always valid. This guide synthesises the growing body of masters-specific research alongside first principles to give practical guidance for athletes competing beyond 40.
Protein: The Most Critical Adjustment
Anabolic resistance — the reduced sensitivity of aging muscle to the muscle protein synthesis stimulus from protein ingestion — is the most consistently documented age-related change in sports nutrition research. In young athletes, 20–25g of leucine-rich protein produces a near-maximal muscle protein synthesis response. In masters athletes (40–60+), the threshold shifts to 35–40g per meal — and some research suggests even higher doses (40–50g) may be required to maximally stimulate MPS in athletes over 55.
- Daily protein target: 1.8–2.2g/kg body weight for masters endurance athletes — approximately 20% above the recommendation for younger athletes. For a 75kg masters runner, this is 135–165g daily.
- Per-meal distribution: 35–45g high-quality protein per meal (4 meals or 3 meals plus a recovery shake). Spreading protein in smaller doses of 20g each produces lower total MPS than larger, less frequent doses in masters athletes.
- Pre-sleep protein: 40g casein protein before sleep enhances overnight MPS and reduces the muscle protein breakdown that occurs during the extended overnight fasting window. More potent in masters athletes than younger ones due to greater overnight catabolic sensitivity.
- Leucine prioritisation: Prioritise whey, eggs, milk, and lean meat as primary protein sources — highest leucine content. If using plant proteins, the 35–45g target per meal accounts for the lower leucine density of plant sources.
Bone Health: Calcium, Vitamin D, and Collagen
Bone mineral density decreases at approximately 1% per year after peak bone mass (reached in the early 30s), accelerating in women post-menopause (1.5–3% per year in the first 5–10 years). Masters endurance athletes face a specific paradox: running generates bone-loading stimuli that preserve density, but high training volume — particularly without adequate energy availability — can paradoxically accelerate bone loss through hormonal suppression (low energy availability syndrome, previously known as RED-S):
- Calcium: 1,000mg daily (men 40–70, pre-menopausal women); 1,200mg daily (women post-menopause, men 70+). Prioritise dairy, fortified plant milks, canned salmon with bones, and leafy greens. Supplement if dietary calcium consistently falls below target.
- Vitamin D: 25(OH)D levels of 40–60 ng/mL recommended. Most masters athletes require 2,000–4,000 IU D3 daily to maintain sufficiency — test and dose accordingly. Vitamin D is critical for calcium absorption and bone mineralisation, and insufficiency significantly elevates fracture risk in masters athletes.
- Collagen: 15g hydrolysed collagen + 50mg vitamin C daily before weight-bearing exercise to support connective tissue synthesis. The slower collagen turnover in masters athletes (compared to younger athletes) makes this supplementation increasingly relevant above age 40.
Carbohydrate Timing and Glycogen Dynamics
Glycogen resynthesis rates decline modestly with age — not enough to require dramatic dietary changes, but enough to make timing precision more important. Masters athletes benefit more from immediate post-exercise carbohydrate consumption (within 30 minutes) compared to younger athletes who have more metabolic flexibility in the timing window. Target 60–80g carbohydrate within 30 minutes of any session exceeding 60 minutes. The insulin response to carbohydrate is slightly blunted with age, which paradoxically means the post-exercise window — when muscle GLUT4 transporters are upregulated independently of insulin — is relatively more important for glycogen repletion.
Anti-Inflammatory Nutrition Strategy
Chronic low-grade inflammation ("inflammaging") is a hallmark of biological aging that impairs recovery, muscle repair, and training adaptation in masters athletes. Nutritional anti-inflammatory strategies are more impactful in masters athletes than younger ones:
- Omega-3 fatty acids: 2–4g EPA+DHA daily (higher than the standard 1–2g recommendation) for masters athletes. Attenuates post-exercise inflammation and muscle protein breakdown. Evidence for improved muscle protein synthesis in masters athletes specifically.
- Tart cherry concentrate: 30mL twice daily around training blocks. Anti-inflammatory anthocyanins reduce post-exercise DOMS duration and muscle damage markers — consistently effective in masters athlete studies.
- Polyphenol-rich diet: Berries, dark leafy greens, olive oil, and dark chocolate all contain polyphenols that modulate NF-κB inflammatory signalling. These are diet patterns, not supplements — the totality of dietary quality matters more than any single food. Use the NorthLine Magnesium Intake Estimator to check if your current diet is meeting the elevated magnesium requirements that accompany higher protein and training volume in masters athletes — magnesium deficiency worsens sleep quality, muscle function, and bone health simultaneously.