The Science Behind GYMGRL: Creatine, Collagen & BCAAs Explained

Creatine is the most researched performance supplement in existence. The International Society of Sports Nutrition (ISSN) position stand — one of the most comprehensive reviews of creatine research ever published — concluded that creatine monohydrate is "the most effective ergogenic nutritional supplement currently available to athletes" (Kreider et al., 2017).

How it works

Your muscles use adenosine triphosphate (ATP) as their primary energy currency. During high-intensity exercise, ATP is depleted rapidly. Creatine — stored in muscle cells as phosphocreatine — donates a phosphate group to regenerate ATP from ADP, enabling you to sustain effort for longer before fatigue sets in. The result is more reps, more power, more volume — and the accumulated training stimulus that drives long-term strength and body composition change.

Why women specifically benefit

What makes creatine particularly significant for women is baseline levels. Research has established that women naturally have lower muscle creatine stores than men (Harris et al., 1992) — meaning the relative benefit of supplementation is arguably greater. Studies show women supplementing with 3–5g of creatine daily see significant increases in muscle phosphocreatine levels, with performance gains across strength, power, and high-intensity endurance (Smith-Ryan et al., 2021).

Emerging research is also exploring creatine's role in cognitive function and mood regulation — areas of particular relevance to women, given creatine's involvement in brain energy metabolism (Allen, 2012). Some early evidence suggests creatine may help mitigate symptoms of depression and cognitive fatigue, particularly during hormonally active phases of the menstrual cycle.

Collagen is the most abundant protein in the human body — making up approximately 30% of total protein mass. It forms the structural scaffold of skin, bones, tendons, ligaments and cartilage. From our mid-twenties, the body's natural collagen production begins to decline at roughly 1% per year (Shuster et al., 1975). By our thirties and forties, this decline becomes both visible and felt: in the quality of skin, the resilience of joints, and the pace of recovery from training.

Why hydrolysed makes the difference

Not all collagen supplements are created equal. Hydrolysed collagen peptides — the form used in GYMGRL — have been enzymatically broken down into short-chain amino acids (primarily glycine, proline and hydroxyproline) that are absorbed rapidly into the bloodstream. A landmark study by Shaw et al. (2017) demonstrated that collagen peptide supplementation significantly increased collagen synthesis in connective tissue, particularly when taken alongside vitamin C before exercise — which is precisely why GYMGRL's formulation includes vitamin C.

The joint health evidence

For athletes and active women, collagen's most compelling evidence lies in joint integrity. A randomised, double-blind, placebo-controlled study by Clark et al. (2008) followed 147 athletes over 24 weeks and found that collagen peptide supplementation significantly reduced joint pain during activity compared to placebo. A more recent study by Dressler et al. (2018) found improvements in ankle joint stability following collagen supplementation — a meaningful finding for women who train at high frequency.

Skin, hair and the visible dimension

Multiple clinical trials have demonstrated that collagen peptide supplementation improves skin elasticity, hydration and the reduction of fine lines. Proksch et al. (2014) showed statistically significant improvements in skin elasticity after just 8 weeks of supplementation in women aged 35–55. This isn't a vanity add-on — it's a clinically evidenced outcome of the same mechanism that supports joint health.

Branched-chain amino acids — leucine, isoleucine and valine — are three of the nine essential amino acids your body cannot synthesise and must obtain from diet or supplementation. They are unique among amino acids in that they are metabolised directly in muscle tissue rather than the liver, making them particularly relevant to muscle performance and recovery.

Leucine and the mTOR switch

Leucine is the key driver. It directly activates the mTOR (mechanistic target of rapamycin) pathway — the principal regulator of muscle protein synthesis (Norton & Layman, 2006). Think of mTOR as the switch that tells your muscles to rebuild and grow stronger after training. Leucine flips it. Isoleucine and valine support glucose uptake into muscle cells and serve as a metabolic fuel source during prolonged exercise.

Recovery and DOMS reduction

The clinical evidence for BCAA supplementation in reducing exercise-induced muscle damage and delayed onset muscle soreness (DOMS) is robust. A meta-analysis by Rahimi et al. (2017) found that BCAA supplementation significantly decreased muscle soreness and markers of muscle damage compared to placebo across multiple studies. For women training 4–6 times per week, faster recovery means the ability to maintain training quality across every session.

Sports nutrition research has been conducted predominantly in young men. The result is a supplement landscape filled with products that fail to account for how female physiology, hormonal cycles and specific nutrient demands differ. Here is what the evidence tells us about women specifically.