Home / Browse by identity / Swimming

Supplements for swimmers

Swimming 40–70 km a week in a buoyant environment reduces bone density over time. Sodium levels fall before dehydration is felt, and standard hydration checks miss this. Here's the load your training creates, and the formula it suggests.

Swimmer Profile Estimated — not measured
Vitamin D (25-OH) 18–35 nmol/L
0reference 50–150255
Hatched = the band we'd estimate. A panel replaces it with a value. Estimate
The physiological load

Why swimming moves these markers

Not because you're a swimmer. Because of five specific things a high-volume swim week does to you.

Driver 01 Bone loading deficit from non-weight-bearing training CaVit D

Swimming 40–70 km a week in a buoyant environment means skeletal loading is minimal, leading to lower bone density compared to sedentary controls. The training load itself is the reason, as buoyancy negates the impact that typically stimulates bone growth. Simply increasing training volume won't address this, as the water's support reduces the mechanical strain needed for bone adaptation.

Driver 02 Unnoticed fluid loss in cool immersion NaMg

Immersion in water suppresses thirst and masks sweat, yet swimmers can lose up to 1-2 litres per session. The cool sensation of the pool misleads athletes into underestimating fluid loss. Replacing fluid based solely on perceived thirst fails to replenish electrolytes lost, risking dehydration and electrolyte imbalance over time.

Driver 03 High training volume with truncated recovery windows

Water conducts heat 25 times faster than air, increasing the thermoregulatory cost during swimming. This heightened energy expenditure isn't felt due to the water's cooling effect. Relying on perceived exertion to gauge energy needs underestimates the metabolic demand, potentially leading to inadequate energy intake and compromised performance.

Driver 04 Minimal sunlight exposure from dawn-to-dusk indoor training Vit D

Early morning and late evening sessions mean swimmers see little sunlight, especially in winter. Cutaneous vitamin D synthesis drops to near zero at northern latitudes during these months. Assuming outdoor time equates to adequate vitamin D ignores the reality of indoor training and geographical limitations, risking deficiency without visible symptoms.

Driver 05 Chlorine Exposure

Thousands of hours in chlorinated pools expose swimmers to chlorine and chloramine, which affect the airways. The oxidative stress from this exposure is significant, yet often overlooked. Simply managing airway irritation without addressing the underlying antioxidant load fails to mitigate the long-term respiratory impact.

The starting formula

What these five imply

Swimmers often underestimate the impact of their environment on bone density and fluid balance. These estimates are what a panel replaces, providing precise measurements instead.

Refine this with my answers

* Claims shown are limited to authorised structure/function statements. Vitamin D contributes to the maintenance of normal muscle function. Calcium is needed for the maintenance of normal bones. Vitamin K contributes to the maintenance of normal bones. Magnesium contributes to normal muscle function and to the reduction of tiredness and fatigue. Magnesium contributes to normal energy-yielding metabolism. Selenium contributes to the protection of cells from oxidative stress. Body+ products are food supplements and are not intended to diagnose, treat, cure or prevent any disease.

Swimmers — starting stack Daily
Vitamin D3 50 mcg Calcium citrate is absorbed without the need for gastric acid, making it suitable for swimmers who may have lower stomach acidity. It supports bone density, which is crucial given the minimal skeletal loading in swimming.
Calcium citrate 950 mg This sodium-forward blend is designed for during-session hydration, aligning with the significant fluid loss swimmers face. It adjusts to actual sweat rates, which are often underestimated in water.
Vitamin K2 (MK-7) 50 mcg Ubiquinol, the reduced form of CoQ10, is better absorbed with dietary fat, aiding energy metabolism. It addresses the increased thermoregulatory demand swimmers face due to water's rapid heat conduction.
Magnesium glycinate 400 mg Vitamin D3 in cholecalciferol form is fat-soluble, optimizing absorption when taken with meals. Measuring vitamin D status is preferred as sunlight exposure is unreliable for swimmers training indoors.
Creatine monohydrate 3000 mg L-carnitine tartrate facilitates fatty-acid transport into mitochondria, supporting energy metabolism. This is vital for swimmers who may underestimate their energy needs due to the cooling effect of water.
Selenium (selenomethionine) 55 mcg
Within EU/CH food-supplement limits Draft
The precision path

Every number above is an estimate

Calcium is the need where guessing wrong costs most, as bone density changes are subtle. With one needs and one markers, precision matters.

Upload a panel
Deeper

The bone load problem in swimming

Bone load is a critical factor for swimmers due to the buoyant environment of the pool. Unlike other athletes, swimmers experience minimal skeletal loading, which can lead to lower bone density over time. Understanding this marker helps in addressing the unique challenges faced by swimmers in maintaining bone health.

Calcium absorption timing In swimming, the buoyant environment means skeletal loading is minimal, leading to lower bone density compared to other athletes. This is counter-intuitive, as one might expect high training volumes to increase bone density. However, the lack of impact loading in water negates the mechanical strain needed for bone adaptation. Calcium absorption competes with iron and zinc, so timing intake away from these minerals is crucial to support bone health despite the low-impact nature of the sport.

Standard bone density tests Standard bone density tests might show values within normal ranges, misleading swimmers into thinking their bone health is adequate. However, these tests don't account for the unique lack of impact loading in swimming, which can lead to lower bone density over time. A swimmer's bone density might appear normal, but without the mechanical strain typical in other sports, the reading doesn't reflect the potential for future issues. See the evidence section

No blanket calcium recommendations We refuse to recommend calcium supplements based solely on general guidelines or assumptions about training volume. The interplay between calcium, iron, and zinc absorption means that indiscriminate supplementation can lead to unintended imbalances. Without precise measurements, pushing calcium could do more harm than good, especially in a cohort with unique loading conditions.

Testing and retesting strategy

For swimmers, monitoring calcium and vitamin D is essential, especially given the minimal skeletal loading and limited sunlight exposure. Testing should occur at the beginning of the training season and be retested every 8–12 weeks to track changes and adjust supplementation as needed. This ensures bone health is supported without unnecessary supplementation.

Adjacent profiles

Closest load patterns to this one