The Only Supplements That Actually Improve Athletic Performance

The supplement industry sells you 10,000 products. The research supports about four of them.

If you’re an active woman over 35 — lifting, running, training consistently — you’ve probably spent money on supplements that did nothing. BCAAs that tasted like regret. Pre-workouts that just made you itchy. Fat burners that burned your money.

Here’s what the actual science says works, why it works, and what matters more for your demographic than the generic “bro science” advice you’ll find everywhere else.

What’s actually happening

Athletic performance supplements fall into three categories: things that increase energy output, things that speed recovery, and things that prevent decline. Most products on the shelf promise all three and deliver none.

A comprehensive review in Nutrients identified the top five supplements with consistent evidence across multiple studies: creatine monohydrate, caffeine, beta-alanine, sodium bicarbonate, and nitrate/beetroot juice (Antonio J et al., 2024). Everything else — BCAAs, glutamine, testosterone boosters, fat burners — either lacks sufficient evidence or shows effects so small they don’t matter in practice.

For women specifically, the picture is more nuanced. The International Society of Sports Nutrition published a position stand on nutritional concerns of the female athlete that highlights how hormonal fluctuations across the menstrual cycle and perimenopause affect nutrient needs, recovery capacity, and supplement metabolism (Sims ST et al., 2023).

What this means: the supplements that work for a 25-year-old male powerlifter and the supplements that work for a 42-year-old woman doing strength training aren’t identical. The mechanisms are the same, but the dosing, timing, and additional considerations differ.

Why this is happening to you specifically

If you’re training hard and not seeing performance improvements, the bottleneck probably isn’t willpower or programming. It’s one of three things: insufficient creatine stores, poor recovery nutrition, or hormonal shifts that change how your body uses the supplements you’re already taking.

Here’s what most women don’t realize: your baseline creatine stores are 20–30% lower than men’s — a gap that widens during perimenopause as estrogen declines. That’s not a fitness issue — it’s a metabolic fact. Women also tend to have lower intramuscular carnosine levels, which directly affects high-intensity exercise capacity.

When you add perimenopause to the equation, estrogen decline reduces your body’s ability to synthesize creatine from amino acids. You’re not just dealing with less creatine storage — you’re dealing with less efficient production. This is one reason women in their 40s often feel like training “stopped working” even when they haven’t changed anything.

A review on post-exercise recovery confirmed that nutrient timing and specific supplement choices have measurable effects on subsequent exercise performance — but only when the fundamentals (sleep, protein intake, training consistency) are already dialed in (Naderi A et al., 2025).

What you can do today

1. Creatine monohydrate — 3–5g daily, every day. This is the single most researched and effective sports supplement in existence. It increases phosphocreatine stores in muscle, allowing you to produce more ATP during high-intensity efforts. The co-supplementation research on creatine and beta-alanine showed that creatine alone improves strength and power output, while the combination adds endurance benefits (Ashtary-Larky D et al., 2025).

For women: take 5g daily if you weigh over 140 lbs, 3g if under. No loading phase needed — that’s outdated advice. Take it at any time of day. It doesn’t cause bloating in most women at these doses, despite what you may have read.

2. Beta-alanine — 3.2–6.4g daily, split into doses. Beta-alanine increases intramuscular carnosine, which buffers hydrogen ions during high-intensity exercise. Translation: you can push harder for longer before your muscles “burn out.” The tingling sensation (paresthesia) is harmless and decreases with consistent use.

Split your dose into 2–3 servings throughout the day to minimize tingling. It takes 2–4 weeks of consistent use to see effects — this isn’t an acute performance enhancer.

3. Electrolytes — sodium, potassium, magnesium — during and after training. This isn’t about fancy branded packets. It’s about replacing what you lose in sweat. The position stand on nutrient timing emphasized that post-exercise sodium and potassium intake significantly affects rehydration and subsequent exercise performance (Kerksick CM et al., 2017).

Magnesium Glycinate with Zinc (Organics Ocean) — I recommend this specific form because glycinate is better absorbed than oxide, and the zinc supports the hormone cofactor pathways that matter for women in perimenopause.

4. Protein timing — 20–40g within 2 hours post-training. Not a supplement in the traditional sense, but worth stating explicitly. The American College of Sports Medicine position stand on nutrition and athletic performance confirmed that protein intake around training supports muscle protein synthesis — but the effect is modest if total daily protein is already adequate (Med Sci Sports Exerc, 2009).

For women 35+, aim for 1.4–1.6g protein per kg bodyweight daily. If you’re 150 lbs, that’s roughly 95–110g per day. Most women eating “healthy” are getting half that.

What to stop doing

Stop taking BCAAs. If you’re eating adequate protein (which includes all essential amino acids), BCAAs provide no additional benefit. Multiple systematic reviews have confirmed this. You’re paying for flavored water.

Stop cycling creatine. There’s no benefit to “loading, then cycling off.” Creatine works by saturating muscle stores. If you stop taking it, stores decline within 4–6 weeks. Just take 3–5g daily, forever.

Stop buying pre-workouts with proprietary blends. If the label doesn’t list exact amounts of each ingredient, you’re buying a mystery box. The only proven ergogenic aids in most pre-workouts are caffeine (which you can buy for $0.05) and possibly citrulline malate (which most blends underdose anyway).

Stop ignoring iron. If you’re a menstruating woman who trains, your iron needs are significantly higher than sedentary women. Low ferritin (even within “normal” range) directly impairs endurance performance. The same pattern shows up in magnesium deficiency — standard blood work misses functional deficiency. Get your ferritin tested — not just hemoglobin.

The supplement / product question

Beyond the magnesium recommendation above, one other supplement deserves attention for active women:

Nordic Naturals Ultimate Omega — High Potency Fish Oil — Omega-3s reduce exercise-induced inflammation — the same mechanism we covered in our deep dive on omega-3s and support the recovery process. For women in perimenopause, they also support the estrobolome — the gut bacteria that metabolize estrogen — which indirectly affects training recovery and body composition.

Do not take more than 3g of combined EPA/DHA daily without medical supervision. More is not better with omega-3s — it can thin your blood and interact with medications.

If you’re already taking omega-3s for general health, the athletic benefit is a bonus. Don’t double-dose.

What we still don’t know

Why women respond differently to creatine dosing than men. The standard 3–5g recommendation comes primarily from male-dominated studies. Emerging research suggests women may benefit from slightly different protocols — particularly around menstrual cycle timing — but the evidence isn’t strong enough yet to make specific recommendations.

This matters because the “take 5g daily” advice assumes a 180-lb male baseline. If you’re a 135-lb woman, the pharmacokinetics are different. The research is catching up, but it’s not there yet.

Save for later — send to someone who’s tired of buying supplements that don’t work.