Effects of resistance exercise, collagen ingestion and circulating oestrogen concentration on collagen synthesis in a female athlete: A case report

We investigated the effects of resistance exercise (RE), hydrolysed collagen (HC) ingestion and circulating oestrogen concentration on collagen synthesis in a naturally menstruating female CrossFit athlete. In a double-blind, randomised cross-over design, the participant (36 years; height 1.61 m; mass 82.6 kg) consumed 0 or 30 g HC prior to performing back-squat RE when endogenous circulating oestrogen concentration was low (onset of menses, OM) and high (late follicular phase, LF) during two consecutive menstrual cycles. Ten 5-mL blood samples were collected during each of the four interventions to analyse concentrations of serum 17β-oestradiol, and biomarkers of type I collagen turnover, that is serum procollagen type I N-terminal propeptide (PINP, a biomarker of collagen synthesis) and plasma β-isomerised C-terminal telopeptide of type I collagen (β-CTX, a biomarker of collagen breakdown), as well as the serum concentration of 18 collagen amino acids. 17β-Oestradiol concentration was 5-fold higher at LF (891 ± 116 pmol L ⁻¹) than OM (180 ± 13 pmol L ⁻¹). The PINP concentration × time area under the curve (AUC) was higher in the 30 g HC OM intervention (201 μg L ⁻¹ h) than the 30 g HC LF (144 μg L ⁻¹ h), 0 g HC OM (151 μg L ⁻¹ h) and 0 g HC LF (122 μg L ⁻¹ h) interventions. β-CTX concentration decreased 1.4-fold from pre-RE to 6 h post-RE in all interventions. Thus, high circulating oestrogen concentration was associated with lower collagen synthesis following RE in this female athlete. Ingesting 30 g HC, however, augmented the collagen synthesis response at LF and particularly at OM.