An easy-to-understand guide to living bone, low energy availability, RED-S, collagen research and the nutrition active women need before bone loss becomes visible

Bone-health conversations often begin around menopause, when calcium, vitamin D, osteoporosis and bone-density scans suddenly move into focus. But the skeleton does not wait until midlife to become important. Much of the reserve carried into later life is built during childhood, adolescence and early adulthood, then maintained through the premenopausal years.

For female athletes, this creates both an opportunity and a vulnerability. Running, jumping and resistance training can provide valuable mechanical signals to bone. Yet training is only the instruction. The body still needs enough energy, protein, carbohydrate, fat, vitamins, minerals and recovery time to carry out the adaptation.

A 2026 pilot study in premenopausal female distance runners has added an intriguing question: could collagen peptides influence short-term markers of bone remodelling during endurance training? The findings are worth understanding—but they do not overturn the basic hierarchy. Collagen cannot compensate for chronic under-fuelling, menstrual disruption or excessive training load.

 

Bone Health Starts Decades Before Menopause

Peak bone mass is generally reached by late adolescence or early adulthood. Genetics influences the ceiling, but nutrition, hormones, physical activity and health during growth help determine how much skeletal reserve is built. The years that follow are not a “free pass”: active women continue repairing microdamage and maintaining tissue long before menopause begins.

 

The earlier-life perspective is explored in Why Female Athletes Need to Think About Bone Health Earlier.

Bone Is Living, Metabolic Tissue

Bone may feel solid, but it is vascular, innervated and biologically active. It participates in movement, mineral homeostasis and blood-cell production. It also renews itself through remodelling: old or damaged tissue is removed and new matrix is formed.

 

Healthy remodelling is not “formation good, resorption bad”. Both are required. The long-term question is whether rebuilding keeps pace with removal and repeated mechanical stress.

For the deeper biology, read Bone Isn't Solid—It's Living Tissue.

Bone Is More Than Calcium

Most people picture bone as mineral, but bone is a composite material. Its organic matrix is predominantly Type I collagen, together with non-collagenous proteins. Mineral crystals are then organised within this framework.

 

This is why calcium matters without being the whole answer. Vitamin D helps regulate calcium and phosphate biology. Protein provides amino acids for cells and matrix. Magnesium and vitamin K participate in bone-related processes. Energy keeps the cellular work possible. Mechanical loading supplies the signal.

The complete construction model is explained in Why Strong Bones Need More Than Calcium.

Training Is a Signal, Not the Building Material

Running places repeated load through the skeleton. Resistance training asks bone and muscle to tolerate progressively greater force. Jumping and multidirectional sport can supply other loading patterns. These signals can be beneficial because bone adapts to the forces it experiences.

But adaptation has a cost. Exercise creates microscopic strain and uses energy. In a well-supported system, recovery allows repair and strengthening. When load repeatedly exceeds the capacity to recover, microdamage can accumulate faster than it is repaired, increasing the risk of a bone stress injury.

 

The formula is not “more training equals more bone”. It is appropriate load plus sufficient resources plus recovery.

What Is Low Energy Availability?

Energy availability describes the dietary energy left for normal physiological functions after subtracting the energy used in exercise. Low energy availability occurs when too little remains to support the body’s wider needs. It can result from intentional restriction, but it can also happen accidentally when training volume rises, appetite is low, schedules are busy or an athlete underestimates how much fuel her programme requires.

Being lean does not prove that an athlete is well fuelled, and stable weight does not rule low energy availability out. The body can adapt by reducing energy spent on functions that are not immediately essential to survival. Reproductive hormones, thyroid-related physiology, bone turnover, immunity, gastrointestinal function, recovery and mood may all be affected.

 

The practical warning signs and broader RED-S context are covered in Female Athletes, Low Energy Availability & Bone Health: Why Eating Enough Is Part of Injury Prevention.

The Female Athlete Triad and RED-S

The Female Athlete Triad originally described the relationship among low energy availability, menstrual dysfunction and impaired bone health. Relative Energy Deficiency in Sport, or RED-S, expands the model to recognise wider health and performance effects and that athletes of any sex can be affected.

Menstrual function is an important health signal. Missing or increasingly irregular periods are not proof of athletic fitness. They can have many causes and require appropriate assessment, but in an athlete they may indicate that energy availability and reproductive hormone signalling need attention. Lower oestrogen associated with functional hypothalamic amenorrhoea can shift bone remodelling in an unfavourable direction.

Other clues may include persistent fatigue, declining performance, recurrent injuries, frequent illness, poor recovery, mood changes, cold intolerance or gastrointestinal symptoms. None is diagnostic on its own. RED-S assessment is clinical and should consider training, nutrition, menstrual history, injuries, health and psychological factors together.

Bone Stress Injuries Are Not Just “Sore Bones”

Bone stress injuries occur along a continuum from stress reaction to stress fracture when repetitive loading outpaces repair. Common sites in runners include the tibia, metatarsals, pelvis, femoral neck and sacrum, although risk and urgency differ by site.

Localised bone pain that worsens with impact, persists, causes limping or occurs at rest should not be trained through. Early assessment matters because continuing to load an injury can allow it to progress. A history of repeated bone stress injury should also prompt a wider look at energy availability, menstrual function, bone health and training load—not simply a change of shoes.

What the 2026 Collagen Study Actually Tested

The randomised, double-blind pilot trial enrolled endurance-trained premenopausal women aged 18–35 who ran at least 56 kilometres per week. Participants received either 20 g/day of a specific collagen-peptide product or an energy-matched maltodextrin control for four weeks. Assessments included blood markers related to bone formation, bone resorption, osteoclast signalling and inflammation.

 

Researchers reported a group-by-time interaction for P1NP, a marker associated with bone formation, with an increase in the collagen group. CTX-1, a marker of bone resorption, did not show a significant group interaction. Changes were also reported in selected osteoclast-related and inflammatory measures, including IL-6. The study was small, short and designed to detect biomarker signals—not clinical outcomes.

 

Why Biomarkers Are Useful—and Limited

Bone turnover markers can change more quickly than bone density, making them useful for early research. P1NP reflects aspects of Type I collagen formation; CTX reflects breakdown of Type I collagen. They can help researchers see whether biology is moving, but they are surrogate outcomes.

 

The new trial adds to the biomarker level. Larger and longer studies are needed before moving up the ladder.

A 20 g Bone Study Is Not a Universal Collagen Dose

The dose matters because collagen products are often marketed as though “collagen is collagen”. Research uses specific preparations, doses, populations, timing and outcomes. A dose studied for skin hydration is not automatically a bone dose, and a result from one product cannot be assigned to every collagen powder.

Twenty grams of collagen also does not replace complete dietary protein. Collagen has a specialised amino-acid profile rich in glycine, proline and hydroxyproline, but it is not a complete protein and is relatively low in leucine. Female athletes still need complete or complementary proteins supplying all essential amino acids for muscle repair and whole-body protein needs.

For the broader evidence and format comparison, read Collagen Peptides: Benefits for Skin, Joints, Recovery, Gut Health & Healthy Ageing.

The Complete Nutrition Strategy for Active Women

Energy Comes First

A nutrient-dense diet can still be too small. Calcium, vitamin D or collagen cannot compensate when total energy availability is chronically inadequate. Fuel needs rise with training volume, intensity, growth, injury recovery and other life demands.

Protein Supports Bone and Muscle

Bone-forming cells need amino acids, and muscle adapts to training through protein remodelling. Spread complete or complementary protein across meals and snacks instead of relying on one large evening serve. Collagen peptides, if used, should be added to this foundation rather than counted as the athlete’s only protein strategy.

For food sources and practical meal building, explore High-Protein Foods: The Foundation of Muscle, Healthy Ageing & Recovery Nutrition.

Carbohydrate Supports the Work

Carbohydrate helps fuel endurance and high-intensity work, replenishes glycogen and reduces the need to use dietary protein as an energy source. Chronically restricting carbohydrate while maintaining high training volume can make adequate energy availability harder to achieve.

Dietary Fat Supports the System

Fat contributes energy, essential fatty acids and absorption of fat-soluble vitamins. Extremely low-fat eating can be another route into inadequate energy intake and poor dietary variety.

Calcium and Vitamin D Still Matter

Calcium is required for mineralisation and many physiological functions. Useful sources include dairy foods, calcium-set tofu, fortified alternatives, canned fish with edible bones, tahini and selected greens. Vitamin D supports calcium and phosphate regulation; status depends on sun exposure, skin, season, diet and individual factors. Supplement decisions are best guided by need rather than assumption.

The Weekly Pattern Matters

One strong post-training meal cannot repair a week of chronic under-fuelling. Bone responds to the repeated pattern of load, food and recovery. Athletes need enough nutrition on easy days too because remodelling continues between sessions.

The Muscle–Bone Unit

Muscle and bone are mechanically and biologically connected. Muscle pulls on bone, producing strain that bone cells can sense. Stronger muscles also support balance, movement control and protection from falls later in life. Resistance training therefore offers a stimulus that endurance running alone may not fully provide.

More running is not always the answer to better bone health. Training programmes benefit from progressive strength work, variation in loading, adequate recovery and individualisation. Rest is not the absence of training; it is where the body completes the response to training.

See this lifelong partnership in The Muscle–Bone Connection: How Strong Muscles Help Build Strong Bones Throughout Life.

Does Collagen Need to Be Taken Before Training?

The idea is biologically appealing: consume collagen-derived amino acids before a session that mechanically loads bone or connective tissue, so absorbed nutrients are available around the signal. Some connective-tissue studies use pre-exercise timing, often with vitamin C. The 2026 runner pilot, however, standardised intake within one hour of waking rather than testing pre-training timing.

There is not enough evidence to claim that collagen must be taken at an exact minute to support bone. Consistency, the studied dose, total dietary adequacy and the training programme matter more than chasing a perfect clock time.

Vitamin C is required for normal collagen formation, but more does not create unlimited collagen. Regular vitamin C-rich foods such as citrus, kiwifruit, berries, capsicum, broccoli and tomatoes can contribute across the day.

Timing is put in perspective in Protein Timing for Health, Performance & Recovery.

A Practical Bone-Health Framework

Fuel the Athlete

·       Match total food intake to training and life demands.

·       Use carbohydrate before and after demanding sessions according to tolerance and duration.

·       Include complete or complementary protein across meals and snacks.

·       Do not treat low body weight or missed periods as performance achievements.

Train the Skeleton

·       Include progressive resistance training alongside endurance work.

·       Vary load and terrain appropriately rather than repeating one stress endlessly.

·       Increase training gradually and allow tissues time to adapt.

·       Respond early to focal bone pain or repeated stress injuries.

Support the Biology

·       Meet calcium needs through food and fortified options where possible.

·       Assess vitamin D when risk factors or clinical concerns make it relevant.

·       Include dietary fat and a varied range of whole foods.

·       Prioritise sleep and recovery days as part of the programme.

Use Collagen in the Right Place

·       Treat collagen peptides as an optional specialised layer, not the foundation.

·       Match claims to the specific preparation, dose, population and outcome studied.

·       Do not assume a smaller skin-focused serve reproduces a 20 g bone-turnover study.

·       Do not use collagen to mask under-fuelling, menstrual dysfunction or excessive load.

 

A Simple Training-Day Pattern

Before Training

·       Eat a meal or snack containing carbohydrate and some protein according to session timing and tolerance.

·       Arrive hydrated and avoid beginning demanding sessions chronically under-fuelled.

·       If using collagen peptides, follow the selected product and evidence context rather than treating timing as magic.

After Training

·       Replace energy with a proper meal or substantial snack.

·       Include complete protein and carbohydrate.

·       Continue eating normally across the day; recovery is not completed by one shake.

Across the Week

·       Fuel easier days because tissue repair continues.

·       Include resistance training and genuine recovery.

·       Track performance, menstrual function, injury patterns, mood and fatigue—not weight alone.

Try the Recipes

Practical meals make adequate fuelling easier to repeat. These collections provide protein, carbohydrate, fibre and everyday variety for active routines.

12 Easy Recipes for Active Bodies: Protein, Collagen & Everyday Joint-Supporting Nutrition

15 High-Protein, High-Fibre Recipes for Blood Sugar & Metabolic Health

Frequently Asked Questions

Can collagen peptides build stronger bones?

Early research suggests possible effects on selected bone-turnover markers, but evidence is not sufficient to claim that collagen peptides increase bone strength or prevent fractures in female athletes.

What did the 2026 female-runner study find?

After four weeks of 20 g/day collagen peptides, researchers reported changes in P1NP and selected inflammatory or osteoclast-related markers. The small pilot did not test long-term structural or injury outcomes.

Does the study prove collagen prevents stress fractures?

No. Stress-fracture incidence was not measured.

Is 20 g the recommended collagen dose for every woman?

No. It was the dose used in one specific pilot study. Appropriate use depends on the product, purpose and wider diet.

Can collagen replace complete protein?

No. Collagen has a specialised amino-acid profile and does not supply the complete essential amino-acid pattern athletes need.

What is low energy availability?

It is a state in which too little dietary energy remains after exercise to support the body’s normal physiological functions.

Can low energy availability happen without weight loss?

Yes. Weight may remain stable while the body adapts by reducing investment in reproductive, bone, recovery or other functions.

Are missed periods normal for athletes?

No. Menstrual changes have several possible causes and deserve assessment; they should not be dismissed as proof of fitness.

Is running enough for bone health?

Running provides impact loading, but resistance training, varied load, adequate nutrition and recovery add important support.

Does collagen have to be taken before exercise?

There is not enough evidence to require an exact timing window for bone health. Consistency and total nutrition matter more.

Is calcium the most important bone nutrient?

Calcium is essential, but bone also depends on energy, protein, vitamin D, other micronutrients, hormones, loading and recovery.

When should an athlete seek assessment?

Persistent focal bone pain, repeated stress injuries, menstrual changes, substantial fatigue, declining performance or suspected under-fuelling warrant timely professional assessment.

Final Thoughts

The most important lesson from emerging collagen research is not that every female athlete needs another supplement. It is that bone is biologically active, mechanically responsive and nutritionally demanding. A training signal only becomes adaptation when the body has the resources and time to respond.

Collagen peptides may become a useful specialised tool in this field. The 2026 pilot provides an interesting biomarker signal, not proof of stronger bones or fewer injuries. Energy availability, menstrual health, complete protein, carbohydrate, fat, calcium, vitamin D, resistance training and recovery remain the larger story.

Bone health before menopause is not preparation for ageing in some distant future. It is part of performance, recovery and health now—and every well-fuelled training year helps write the skeletal story carried forward.

References and Further Reading

·       Collagen peptides and bone-turnover markers in female distance runners — randomised pilot study

·       2023 IOC consensus statement on Relative Energy Deficiency in Sport

·       Low energy availability in female athletes: from the laboratory to the field — review

·       Energy deficiency, menstrual disorders and low bone mineral density in female athletes — systematic review

·       Reduced energy availability and bone health in physically active populations — review