Heyo,

It's time for another instalment of the Vitamin––the weekly fitness newsletter that helps you be healthier, stronger, and leaner while navigating fitness bullshit.

Building glutes with home workouts?

It depends.

Muscle growth comes down to progressive tension overload and the intensity of your training–are you progressing the amount of reps or weight lifted, and is each set getting you close to failure?

If you can answer yes to both of those, then it doesn't matter if you're using dumbbells, barbells, or just your body weight.

That said, training at home has some obvious practical limitations. Your glutes are a large, powerful muscle group, and while body weight lunges or hip thrusts might be sufficiently challenging if you're an absolute beginner, they won't be as effective the stronger you get.

At this stage, you will need some form of equipment that lets you keep progressing without needing a bazillion reps before the exercise is challenging enough.

Unfortunately, the majority of home workouts I see online are fucking dumb. Performing endless bodyweight booty kickbacks isn't doing anything for muscle growth. Neither is lifting super-light weights that don't provide any challenge.

If you do intend to train at home, then investing in equipment like resistance bands or adjustable dumbbells is always a good idea. Sure, adjustable dumbbells aren't exactly inexpensive, but if you're going to be training consistently for years, they pay for themselves.

What's the deal with collagen?

Collagen supplements have exploded in popularity over the last few years, and you'll hear claims that collagen can make your tendons stronger, protect your joints, and even help you build muscle.

But how much of this is actually true and how much is just marketing bullshit? Let's find out.

Is collagen useful for tendons?

While some evidence suggests that collagen can enhance tendon adaptation, not all studies agree.

For example, a 2024 systematic review and meta-analysis by Bischof et al. found that collagen peptides combined with training produced a small improvement in maximal strength and a moderate improvement in fat-free mass, but tendon outcomes were the least certain. [1]

The inconsistency likely stems from what researchers are measuring and how they measure it.

Some studies assess muscle stiffness or indirect performance outcomes, while others look for structural tendon changes, such as cross-sectional area or mechanical stiffness—adaptations that occur slowly and are harder to detect.

For example, a recent study by Miyamoto and colleagues found that collagen supplementation increased muscle stiffness, but did not increase tendon size, which is what most people picture when they hear "stronger tendons." [2]

In short, collagen + training can slightly improve strength and lean mass, but it does not reliably improve tendon strength or stiffness. Any tendon benefit appears small and inconsistent; certainly not enough to justify the “bulletproof tendon” claims.

One reason collagen’s real-world effects look underwhelming is that simply consuming collagen doesn’t seem to increase how fast your body actually builds connective tissue.

In a tightly controlled study, Kirmse and colleagues had young men lift weights for a week while supplementing with a hefty dose of collagen peptides (30 g per day). [3]

Even though collagen supplementation clearly increased blood levels of collagen-specific amino acids, it did not increase muscle or connective tissue protein synthesis beyond that already stimulated by training alone.

In other words, resistance training itself was doing the heavy lifting (ha ha) for connective tissue remodelling, and adding collagen on top didn’t do much.

This helps explain why larger reviews consistently find little to no reliable improvement in tendon stiffness or mechanical strength with collagen supplementation. Tendons primarily adapt to mechanical loading, not simply to having more collagen floating around in the system.

What about for joint health and pain?

There are a handful of studies reporting improved joint health and pain outcomes [4-6], and a systematic review that described collagen protein as a “promising” avenue for these outcomes [7].

However, these are in the context of osteoarthritis or rheumatoid arthritis, and the benefit is likely small.

The quality of these studies is variable, too, and a high-quality meta-analysis (i.e., a statistical analysis incorporating multiple studies) will be needed in the future.

For now, it’s unknown whether this small benefit persists in people without these conditions, so don’t put your wallet on the line for this one yet.

What about for muscle building?

The problem with collagen is that it has a pretty terrible amino acid profile–it’s rich in non-essential amino acids like proline and glycine but low in essential amino acids like methionine and leucine, and completely lacks tryptophan.

For example, collagen has a Digestible Indispensable Amino Acid Score (DIAAS)–– a method used to rank the quality of different protein sources––of zero. Compare this to milk protein, which has a DIAAS above 1.0. [8]

The studies that have found a benefit of collagen supplementation for muscle gain have compared it to a placebo [9-11].

But this is hardly surprising. If one group receives protein while the other doesn’t, you can expect the protein group to gain muscle.

However, when collagen protein is pitted against a complete protein source, like whey, it underperforms. This holds true even when researchers add extra leucine to the collagen supplement [12] and even when comparing collagen to plant proteins. [13]

So from a muscle growth or retention standpoint, you're better served opting for high-quality protein sources like whey, meat, fish, and eggs.

Recovery and soreness?

The Bischof meta-analysis mentioned earlier [1] also examined recovery and soreness and found that collagen supplementation had no meaningful effect on soreness or strength recovery, with only a very small (and low-certainty) effect on jump performance recovery.

Bottom line

I won't go so far as to say collagen is useless, but it's also nowhere near the miracle supplement it's often sold as.

Taken alongside training, collagen may produce small improvements in strength and modest increases in lean mass, especially compared to doing nothing. But if muscle gain is the goal, you’re far better off prioritising high-quality protein rather than relying on collagen.

As for the joint and tendon claims, the evidence is pretty weak and inconsistent. Increases in tendon size have been reported in some studies, but there’s no reliable improvement in tendon stiffness or mechanical strength, which is what actually matters for performance and injury risk.

And when it comes to recovery and soreness, the evidence is just as underwhelming: soreness doesn’t reliably improve, and any recovery benefits are small and uncertain.

Overall, collagen can be a reasonable “nice to have” if you’ve got the budget and want to experiment, but it certainly doesn't live up to some of the claims circulating online.

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–Aa

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