Description

Focus on Calcium

We all know that calcium is good for our bones, but have you ever considered other ways this mineral may help support your running? 

In this episode we delve into the consequences of suboptimal calcium status on running performance with a particular focus on muscle contraction. We also consider some of the risk factors for poor calcium status before highlighting several key dietary strategies to help optimise a daily intake of calcium.     

SHOW NOTES

(03:13)

Calcium is a mineral that is well known to support bone and teeth. But did you know…..

• 99% of calcium is found in bone and teeth 
• A maximum of 35% of ingested calcium is actually absorbed into the body
• Of the 35% absorbed approx. 50% is excreted via the kidneys
• Calcium is held in a reservoir within bone, from which the body draws it when required 

(07:32)

Calcium has many functions within the body including:

• Regulation of hormonal release 
• Transmission of nerve impulses
• Blood clotting

But the principle ones a runner would want to focus on include:

• Bone health
• Muscle contraction
• Vasodilation
• Vitamin D and its metabolism
• Biosynthesis of ATP (adenosine triphosphate - our energy currency) 

(09:11)

Muscle Contraction is complex but put simply; each muscle fibre (or muscle cell) is made up of smaller fibres called myofibrils. These myofibrils contain even smaller structures called actin and myosin filaments. It is these filaments (actin and myosin) that slide in and out between each other that form the muscle contraction. Calcium is crucial to activating this muscle contraction cycle. If there is insufficient calcium available then the muscle contraction cycle slows and the muscle becomes fatigued really quickly.  

(14:11)

The hormones Calcitonin and Parathyroid hormone (PTH) alongside the pro-hormone Vitamin D are very important for maintaining blood serum Calcium balance (homeostasis). 

• Calcitonin helps build born when there's sufficient calcium available
• PTH stimulates bone demineralisation when blood calcium levels are low
• Vitamin D encourages absorption of calcium from the digestive tract when directed by PTH

The kidneys are also important in maintaining Calcium balance. When stimulated by PTH, they will increase the reabsorption of Calcium, thus less is excreted.  

Calcium plays an important role in the REGULATION of the energy cycle by activating various enzymes to produce ATP and as we know ATP is important within the muscle contraction cycle.

(20:00)

Thinking about the runner; if calcium levels are insufficient then it could lead to incomplete muscle contraction and early fatiguing of muscle. It may also increase the runner’s risk of developing a stress fracture, which could remove them from running for at least 12 weeks to recover.   

(23:16)

FEMALE FACTORS:

• It is thought that a low vitamin D and Calcium status could MODESTLY increase the risk of a woman moving into early menopause….so something to bear in mind for all our listeners who are pre-menopause. 
• A low vitamin D and Calcium status is thought to be associated with female conditions such as PCOS, PMS, and Endometriosis. Studies suggest this may be because the ovaries are a target organ for Active vitamin D3 PLUS Vitamin D3 receptors are found on ALL reproductive tissue. Studies that have supplemented Ca have found a positive correlation in the reduction of early menopause. 
• Females who are vegetarian or vegan may be at an even greater risk if they are not actively monitoring their Ca AND vitamin D...