Some injuries refuse to follow the usual script.
A shin splint settles down, then returns. A tendon improves for three weeks and stalls. A stress fracture heals — only for another one to appear somewhere else eight months later. When that pattern keeps showing up in someone who trains, the problem often isn’t the tissue itself. It’s whether the body is getting enough fuel and nutrients to rebuild what training breaks down.
Researchers call this Relative Energy Deficiency in Sport, or RED-S. And it is far more common than most athletes, parents, and coaches realize.
The pattern that starts this conversation
Most people who walk into Performance Sport Care in Walnut Creek have already been somewhere else. They’ve tried the adjustments, the red-light therapy, the rest, the electrical stimulation. Something helped for a while. Then the same problem returned — or a new one showed up nearby.
When a complaint keeps coming back in someone who trains hard, the useful question changes. It stops being “What’s wrong with this body part?” and becomes “What’s preventing this tissue from adapting?”
Tissue only heals and gets stronger when the body has the resources available to spend on the project. If those resources are missing, no amount of well-aimed local treatment can finish the job.
Energy availability is one of the items on that list — and one of the easiest to miss. Nothing about it shows up on an X-ray, an MRI, or a standard orthopedic exam. You only find it when the investigation is wide enough to look for it.
What RED-S actually is
Here’s the simple version.
Your body spends energy on two jobs: the training you do, and the ordinary work of staying alive and repairing itself — building bone, making hormones, replacing muscle protein, running your immune system, digesting food, keeping you warm.
Whatever is left after training pays for all of that. Researchers call the leftover “energy availability.”
When training goes up and eating does not go up with it, that leftover shrinks. Push the shortage far enough, for long enough, and the body starts economizing.
It does not economize by sending you a clear warning. It economizes by quietly defunding the departments that will not complain right away.
The International Olympic Committee once described a rough numerical threshold for concern. Its 2023 consensus, and the 2025 update to the Female Athlete Triad guidelines, both moved away from treating any single number as a hard line.
Energy availability is better understood as a range. Some shortfall is normal and the body can adapt. It becomes a problem depending on how deep it goes, how long it lasts, and who it is happening to.
The bone problem — and why the same athlete keeps breaking down
Healthy bone is constantly being torn down and rebuilt. It is a construction site that never closes. That ongoing process is how bone adapts to training in the first place: you load it, and it responds by building denser and stronger in the places that took the stress.
Under-fueling breaks that cycle in a specific and damaging way. A 2025 analysis of 82 elite athletes found that RED-S is marked by bone-breakdown markers rising at the same time bone-building markers fall.
Demolition continues.
Construction stops.
That is the mechanical answer to a question many athletes eventually ask: Why does this keep happening to me?
The skeleton is being asked to adapt to a training load while it is being denied the resources to do it.
Among 458 recreational female runners, those with two or more lifetime stress fractures screened at risk for low energy availability 85% of the time — compared with 49% of those who had one or none.
In a study of more than 3,000 British servicewomen, those at high risk had markedly higher odds of a bone stress injury in the previous year — and markedly higher odds of any injury that cost them training time.
It is not only bones.
A 2026 study followed adolescent female athletes across a nine-week season. Those who screened at risk beforehand were injured more often, and 93% of those injuries were ordinary musculoskeletal ones: knee strains, ankle sprains.
Not exotic.
Exactly the kind of thing that walks into a sports chiropractic office on a Tuesday afternoon.
This is not rare — and it is not only a women’s issue
A 2024 systematic review pooled 6,118 athletes across 46 studies. Nearly 45% met criteria for low energy availability.
The split by sex is the part most people get wrong:
- 44.2% of female athletes
- 49.4% of male athletes
Male athletes are affected at least as often — and they are screened for it far less. One practical reason: the most widely used screening questionnaire cannot be used in men at all, because roughly half its questions concern menstrual function. There is no equally obvious signal in male athletes.
Among 50 competitive male road cyclists, 28% had low energy availability and 44% had low bone density in the lumbar spine. Energy availability was the single strongest predictor of that bone density.
Awareness is also low. In one elite group of 260 athletes, fewer than 10% had even heard of RED-S.
Most affected athletes are not dieting
This is the finding that should change how the conversation is framed at home.
Researchers screened 464 female adolescent athletes. Thirty met clinical indicators of low energy availability. Of those thirty, 80% showed no signs of disordered eating and did not even report wanting to lose weight. They still had significantly lower bone density than their peers.
In other words, the dominant pathway into this problem is not restriction. It is arithmetic. Training went up — a new season, a second sport, a club team, a growth spurt — and eating stayed where it was, because nobody mentioned that the number moves when the schedule changes.
That reframes the whole issue. For most affected athletes this is a math problem, not a psychological one. The indicated fix is education about fueling.
In California, nutritional and dietary counseling is explicitly within a chiropractor’s scope of practice. At Performance Sport Care this is not a topic left for someone else to eventually discover. It is part of the evaluation and part of the ongoing plan.
The growth window: why the stakes are highest for teenagers
Roughly 90% of a person’s peak bone mass is built by age 18. The teenage years are the deposit window. What gets banked there is one of the strongest predictors of fracture risk decades later. Miss the deposit and there is no comparable second chance to make it up.
Here is the part that should get a parent’s attention.
Researchers followed elite adolescent male endurance athletes for three years. Most of them failed to accumulate the bone they should have been accumulating during puberty — even while their aerobic capacity and strength numbers were going up.
Nothing in the athlete’s experience of training would have signaled a problem.
The performance was improving.
The skeleton was not.
A three-year longitudinal study of adolescent endurance athletes found that under-fueled years produce less accrual than expected during the exact window when most of that bone should be deposited — while training performance continued to improve.
The lesson generalizes past teenagers. Improving performance is not evidence that fueling is adequate.
A 2025 review makes the related point clear: dropping body mass does not reliably improve performance either. Short-term severe energy restriction impaired power, sprinting, and endurance — even as the weight came off.
And the IOC’s own working group on body composition found no body-fat cut-off that predicts a performance advantage.
What this changes about the examination
None of the above is visible on a regional orthopedic exam. It is visible in the history — if the history goes looking for it.
For a recurring or non-resolving complaint in someone who trains, the intake at Performance Sport Care extends past the painful area to the factors that determine whether that tissue can actually rebuild:
- What is actually being eaten, including carbohydrate specifically as well as protein. A controlled trial in 28 elite racewalkers found that short-term carbohydrate restriction suppressed bone-building markers more severely than energy restriction did. An athlete eating “clean” and low-carb while training hard can be a live risk case even at reasonable total calories.
- Training load and how recently it changed. Twelve or more hours a week of purposeful exercise is by itself a significant risk factor for bone stress injury.
- Sleep. Women with a history of high-risk bone stress injury were far more likely to average under seven hours on weeknights (80% versus 33%).
- Work and life energy demand. The formula researchers use has no line item for a framing carpenter’s day or a nurse’s twelve-hour shift. Intake that looks fine on paper may not be.
- Injury history and pattern — particularly repeat bone stress injuries, and injuries at sites rich in the spongy inner bone that turns over fastest: pelvis, sacrum, hip, heel.
- Menstrual history where it applies, plus unexplained fatigue, frequent illness, digestive complaints, iron status, and changes in mood or irritability in athletes of any sex.
- Weight history. The gap between an athlete’s lowest and highest weight at current height distinguished the high-risk group in one study.
There is precedent for this kind of catch coming from a chiropractic office. When four chiropractic clinics screened their chronic back-pain patients for a systemic inflammatory arthritis, more than 10% of those referred turned out to have an undiagnosed case. That condition otherwise averages about ten months from back-pain diagnosis to specialist referral, after which the diagnosis usually follows within a month.
The structure of the RED-S problem is the same: a long quiet runway, generic early symptoms, a musculoskeletal complaint at the front door, and a treating clinician positioned to notice early if the history is wide enough to include it.
What treatment looks like
Restoring energy availability comes first
Every consensus document agrees on this: eat more for the load being trained, moderate the load where that is appropriate, or both. Everything else runs alongside it rather than instead of it.
The results here are encouraging and reasonably fast. Multiple intervention studies over three to nine months restored menstrual function in athletes with exercise-related menstrual disturbance using only modest increases in intake.
Bone is slower than hormones
Bone recovery takes longer, and that is exactly why the loading work matters.
A twelve-month randomized trial increased energy intake in 76 exercising women with menstrual disturbance. Menstrual frequency improved. Bone density did not change within the study window. The authors concluded that a year was too short and the increase in intake too small. Bone recovery is a multi-year project.
Supervised strength work is a named part of RED-S recovery
A 2024 commentary in the International Journal of Sports Physiology and Performance set out the practical guidance for musculoskeletal training during recovery from RED-S. Its recommendation is specific: training should be supervised, prescribed, and gradually progressed. It should combine resistance training with high-impact work, starting with movement competency and progressing toward higher intensities for the greatest long-term effect on bone and strength — assuming energy needs are being met as part of recovery.
That is a description of a treatment component, not an optional add-on. It is also a precise description of what happens at Performance Sport Care: progressive resistance and impact work delivered under Dr. Cancel’s on-site clinical supervision, built around what the examination found, and adjusted as the athlete’s capacity changes.
A separate review examined high-impact loading specifically as a bone countermeasure in endurance athletes with low energy availability. The logic is straightforward: high-impact work is both strongly bone-building and relatively cheap in energy terms — important when raising intake or reducing training volume is difficult.
An athlete who restores fueling and then sits still has done only half the work. The skeleton rebuilds in response to load. It needs both.
The complaint they came in with still gets treated
Nobody books an appointment because of a bone marker. They book because something hurts. That complaint is real and it is addressed on its own terms — manual therapy, joint and soft-tissue work, and activity modification to bring irritability down far enough that the loading phase can actually proceed.
The evidence supports that combination rather than any single technique used alone. A network meta-analysis of 119 randomized trials covering nearly 12,500 patients with chronic neck pain found that combined active and passive care (exercise together with manual therapy) produced clinically meaningful improvements versus inactive treatment. An umbrella review of shoulder pain research reached a similar conclusion: exercise as first-line care, with manual therapy strongly recommended as an added therapy in the early phase.
The pattern across this literature is consistent, and it is the sequence used here: hands-on work earns its place early and in combination; progressive loading carries the durable result. In a RED-S case, that loading phase does double duty — it is also the bone intervention.
Coordination when the case is bigger than one office
Where the findings call for it, Dr. Cancel moves quickly to get the medical side of the case started. In practice that usually means directing the patient to their primary care physician with a specific request for the studies the picture warrants — vitamin D, a complete blood count, and an iron panel with ferritin at minimum, with bone-density imaging and expanded testing where indicated.
Knowing which tests to ask for is often what turns a vague concern into an actual medical workup, and it puts the results in front of the physician who will manage them.
Recognizing the problem early and moving quickly to appropriate medical care is the point. It is entirely compatible with continuing to treat what the patient came in for.
When an injury keeps coming back, or progress stalls despite the work, it deserves an evaluation that looks past the painful area.
For parents: what to watch for and what to do
Here is the whole thing in one sentence: If your teenager’s training has gone up and their eating has not gone up with it, the body starts economizing — and the first accounts it cuts are the ones with no immediate symptoms: bone, hormones, immune function, and recovery.
Signals you can notice at home
In training and performance
- Training volume is up, but performance has flattened or is going backwards
- Recovery between sessions takes longer; soreness lingers more than it used to
- Strength or power has stopped progressing despite consistent work
- Coordination or focus falls apart late in sessions and games
Physical signals
- A second stress injury — or the same site failing again
- Injuries that do not resolve on the usual timeline
- Getting sick more often, or missing more training to illness than teammates
- Feeling cold much of the time
- Fatigue that sleep does not fix
- Digestive complaints that have become routine
- In female athletes: periods becoming irregular, lighter, or stopping — or never starting by mid-teens
- In male athletes there is no equivalent visible signal, which is precisely why they get missed. Watch the performance, illness, and injury columns instead.
Logistics — which is usually what this actually is
- Skipping breakfast before morning practice
- A long gap between the last meal and a hard evening session
- Weight-loss messaging reaching the athlete from any adult in their life
- Cutting out a food group — especially carbohydrate — without replacing the energy
- Under seven to eight hours of sleep on training nights
- Adding a second sport, a club season, or a job on top of the existing schedule without changing anything about food
Seven things worth acting on this week
- Reset the fueling when the load changes. Preseason, a new club team, a growth spurt, a second sport — each one moves the number. Food should change at the same time, not after something breaks.
- Fuel before, not only after. Training fasted before school practice is a recurring pattern in this group. So is the four-hour gap between lunch and a six o’clock session.
- Do not cut carbohydrate. The racewalker trial found carbohydrate restriction suppressed bone-building markers more than energy restriction did. In a growing athlete, carbohydrate is not optional.
- Treat sleep as part of the training plan. Averaging under seven hours on weeknights tracked strongly with high-risk bone stress injury history. It is a recovery input, not a lifestyle preference.
- Take a second stress injury seriously as a signal, not just an event. Two or more is the pattern most consistently associated with low energy availability across multiple runner cohorts.
- Pay attention to where the leanness talk is coming from. In one adolescent cohort, 66% of female athletes reported being asked to lose weight by coaching staff. Body composition is one variable among many, and a poor predictor of talent — the IOC’s own review found no cut-off that signals a performance advantage.
- Do not read improving performance as proof of adequate fueling. The adolescent male endurance cohort improved aerobic capacity and strength across three years while failing to bank the bone they needed.
If it helps to have a picture for it: think of a household that took a pay cut nobody announced. Income falls, and the household quietly stops funding the departments that will not complain this month. Building maintenance goes first. The lights stay on and everyone keeps going to work, so from the outside nothing looks wrong — until something structural fails.
The correction is unglamorous and it works. Eat for the load actually being trained, protect the sleep, and keep loading the skeleton progressively so it has a reason to rebuild.
What the research is still arguing about
Worth saying plainly, because it is part of reading this literature honestly.
Energy availability cannot be measured accurately outside a laboratory — the IOC’s own consensus says so. The screening questionnaires are reasonably good at catching intentional restriction and considerably weaker at catching the more common pathway: the failure to scale intake up as training rises.
A 2024 critical review went further and questioned whether RED-S is even separable as a single syndrome. It argued that the symptoms are generic and the causes are almost certainly multiple. Not every study finds the expected injury association either. In one group of 22 elite male volleyball players, 36% showed signs of low energy availability, yet there was no link to bone stress injury or patellar tendinopathy.
The practical conclusion those critics reach is a good one, and it happens to describe how cases are handled here. You do not have to prove that low energy availability is the cause, because every contributing area should be identified and addressed regardless. Incomplete evidence is the ordinary working condition of clinical practice — in this field and every other. What it calls for is a wide differential, honest reassessment, and a plan that gets adjusted as the picture clarifies.
Where this leaves the athlete who keeps breaking down
Dr. Cancel competed as a national-level bodybuilder. That is a sport in which deliberate under-fueling is structural — a planned, finite, closely watched phase with a date on the calendar. Having lived that is part of why the distinction matters to him: a short, supervised deficit with a defined end is a different animal from a teenager or a recreational runner sitting in an accidental one for two years with nobody counting.
No single technique is being sold here as a cure-all. The research does not support that for any provider. What it does support is combining the right approaches in the right order for the presentation in front of you, and being willing to look past the sore spot when the sore spot keeps coming back.
That is what the initial evaluation is for.
Bone, tendon, and muscle are built to rebuild. That is what they do when they are given what they need. When they stop doing that, it is worth finding out why.
Common questions
What is RED-S?
RED-S stands for Relative Energy Deficiency in Sport. It describes what happens when an athlete takes in less energy from food than their training and daily life require, leaving too little for the body’s ordinary maintenance work — building bone, producing hormones, repairing muscle, and running the immune system. The International Olympic Committee now writes it as REDs. It replaced and broadened the older term “Female Athlete Triad,” which described a similar pattern in women only.
Does RED-S only affect female athletes?
No. A 2024 review pooling more than 6,000 athletes found low energy availability in 44.2% of female athletes and 49.4% of male athletes. Male athletes are affected at least as often and are screened far less, partly because the most widely used screening questionnaire relies heavily on menstrual questions and cannot be used in men.
Can you have RED-S without having an eating disorder?
Yes — and that is the more common route. Among 464 adolescent female athletes studied, 80% of those with clinical indicators of low energy availability showed no signs of disordered eating and did not report wanting to lose weight. For most affected athletes this is under-fueling relative to a training load that went up: an arithmetic problem rather than a psychological one.
What are the earliest signs in a teenage athlete?
Usually the unremarkable ones: recovery taking longer, performance flattening despite consistent training, getting sick more often, persistent fatigue, feeling cold, or routine digestive complaints. In female athletes, periods becoming irregular or stopping is a significant signal. A second stress injury is one of the strongest single indicators at any age.
Why would a sports chiropractor like Dr. Cancel ask about my diet, sleep, and training schedule?
Because a recurring musculoskeletal complaint in someone who trains has a differential that extends past the tissue. Injuries heal and tissues adapt only when the body has resources to spend on the project. Diet, carbohydrate intake, training hours, sleep, work demands, injury history, and weight history all bear on that. Nutritional and dietary counseling is within the scope of practice for a Doctor of Chiropractic in California, so it is a working part of the evaluation and the plan.
I keep getting stress fractures. Does that mean I have RED-S?
Not by itself, but it is a strong enough signal to warrant a proper look. Across several runner cohorts, athletes with two or more lifetime stress fractures screened at risk for low energy availability far more often than those with one or none — 85% versus 49% in one study of 458 recreational female runners. Bone stress injuries also have other contributors, including training progression, footwear and surfaces, mechanics, vitamin D and iron status, and bone health issues unrelated to fueling.
Can strength training help if an athlete is under-fueled?
Yes, when it runs alongside restored fueling rather than instead of it. A 2024 clinical commentary describes supervised, prescribed, gradually progressed resistance training combined with high-impact work as an effective non-drug component of RED-S treatment — starting with movement competency and progressing to higher intensities for the greatest long-term effect on bone and strength. That recommendation assumes energy needs are being met as part of recovery.
How long does recovery take?
It depends on how deep and how long the shortfall has been, and different systems recover on different clocks. Menstrual function has been restored in several studies within three to nine months of increased intake. Bone is slower — a twelve-month trial that improved menstrual frequency did not show measurable bone density change within the study window, which the authors attributed to the time frame being too short. Bone recovery is realistically a multi-year project, and progressive loading is a substantial part of it.
Where is Performance Sport Care located?
Performance Sport Care is located at 1776 Ygnacio Valley Rd #106, Walnut Creek, CA 94598, serving Walnut Creek and the surrounding Contra Costa County communities. You can reach the clinic at (925) 945-1155.
Selected references
Mountjoy M, et al. 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine. 2023. — Consensus statement; definition, clinical assessment tool, prevention and treatment principles.
Burke LM, et al. Mapping the complexities of Relative Energy Deficiency in Sport (REDs): development of a physiological model. British Journal of Sports Medicine. 2023. — IOC consensus subgroup; models exposure characteristics alongside individual moderating factors.
Gallant TL, et al. Low Energy Availability and Relative Energy Deficiency in Sport: A Systematic Review and Meta-analysis. Sports Medicine. 2024. — Systematic review and meta-analysis, 59 studies; prevalence by sex, performance impact, injury risk.
Ackerman KE, et al. Low energy availability surrogates correlate with health and performance consequences of Relative Energy Deficiency in Sport. British Journal of Sports Medicine. 2018. — Cross-sectional clinical study, 1,000 female athletes aged 15–30.
Holtzman B, et al. Low energy availability surrogates are associated with Relative Energy Deficiency in Sport outcomes in male athletes. British Journal of Sports Medicine. 2024. — Cross-sectional clinical study in adolescent and young adult male athletes.
Barrack MT, et al. Support for inadvertent undereating in female adolescent athletes with clinical indicators of low energy availability. Journal of Science and Medicine in Sport. 2023. — Cross-sectional study, 464 female adolescent athletes; 80% of those with clinical indicators met no disordered-eating criteria.
Williams NI, et al. 2025 Update to the Female Athlete Triad Coalition Consensus Statement, Part 2: Clinical Guidelines for Screening, Diagnosis, Treatment, and Return to Play. Sports Medicine. 2025. — Graded clinical guidelines; moves away from a fixed energy-availability threshold.
Blagrove R, et al. The Role of Musculoskeletal Training During Return to Performance Following Relative Energy Deficiency in Sport. International Journal of Sports Physiology and Performance. 2024. — Clinical commentary; supervised, progressive resistance and impact training as a treatment component, conditional on energy needs being met.
Hutson MJ, et al. Effects of Low Energy Availability on Bone Health in Endurance Athletes and High-Impact Exercise as a Potential Countermeasure. Sports Medicine. 2020. — Narrative review; impact loading as an energy-efficient bone stimulus under low energy availability.
Stenqvist TB, et al. Relative Energy Deficiency in Sport (REDs) Indicators in Male Adolescent Endurance Athletes: A 3-Year Longitudinal Study. Nutrients. 2023. — Three-year longitudinal study; failure of expected pubertal bone accrual despite improving performance.
Ahmed I, et al. The metabolic crossroad of the adolescent athlete: achieving peak bone mass during athletic development. British Journal of Sports Medicine. 2022. — Perspective; the peak bone mass window and lifetime fracture risk.
Fensham NC, et al. Short-Term Carbohydrate Restriction Impairs Bone Formation at Rest and During Prolonged Exercise to a Greater Degree than Low Energy Availability. Journal of Bone and Mineral Research. 2022. — Controlled dietary intervention, 28 elite racewalkers; isolates carbohydrate restriction from energy restriction.
De Souza MJ, et al. Bone mineral density in response to increased energy intake in exercising women with oligo/amenorrhea: the REFUEL randomized controlled trial. American Journal of Clinical Nutrition. 2022. — Twelve-month randomized controlled trial, n=76; menstrual frequency improved, areal bone density did not within the study window.
Keay N, et al. Low energy availability assessed by a sport-specific questionnaire and clinical interview indicative of bone health, endocrine profile and cycling performance in competitive male cyclists. BMJ Open Sport & Exercise Medicine. 2018. — Cross-sectional study with bone densitometry and endocrine markers, 50 male road cyclists.
Mathisen TF, et al. Best practice recommendations for body composition considerations in sport to reduce health and performance risks. British Journal of Sports Medicine. 2023. — IOC consensus subgroup; no body-composition cut-off signals a performance advantage.
Jeppesen JS, et al. Short-Term Severe Low Energy Availability in Athletes: Molecular Mechanisms, Endocrine Responses, and Performance Outcomes. Scandinavian Journal of Medicine & Science in Sports. 2025. — Narrative review; challenges the assumption that reduced body mass reliably improves performance.
Jeukendrup A, et al. Does Relative Energy Deficiency in Sport (REDs) Syndrome Exist? Sports Medicine. 2024. — Critical review; questions the causal isolation of low energy availability and proposes a multi-category checklist approach.
Sesbreno E, et al. Signs of low energy availability in elite male volleyball athletes but no association with risk of bone stress injury and patellar tendinopathy. European Journal of Sport Science. 2022. — Cross-sectional study, 22 elite male volleyball players; null finding on the injury association.
Castellini G, et al. Some conservative interventions are more effective than others for people with chronic non-specific neck pain: a systematic review and network meta-analysis. Journal of Physiotherapy. 2022. — Network meta-analysis, 119 randomized trials, 12,496 patients; combined multimodal care versus inert treatment.
Pieters L, et al. An Update of Systematic Reviews Examining the Effectiveness of Conservative Physiotherapy Interventions for Subacromial Shoulder Pain. Journal of Orthopaedic & Sports Physical Therapy. 2019. — Umbrella review of 16 systematic reviews; exercise first-line with manual therapy recommended as additional therapy.
Kiwalkar S, et al. Prevalence of axSpA in patients treated for chronic back pain in chiropractic clinics: the Oregon Chiropractic Axial Spondyloarthritis Study (ORCAS). Annals of the Rheumatic Diseases. 2022. — Prospective referral study across four chiropractic clinics; more than 10% of referred patients had undiagnosed spondyloarthritis.
This article is educational and not a substitute for personal advice from a licensed health care provider. Exercises or recommendations that are appropriate for one person may not be appropriate for another, particularly if a history of pain or injury exists.
If you have persistent or worsening pain, pain that radiates into an extremity, pain that is accompanied by fever, or any other unusual symptoms please consult a qualified provider for an individual evaluation or dial 911 in case of emergency.
