Brooks Adrenaline GTS 23 VS Glycerin 21: What Should I Buy?

If you’re a runner looking for a comfortable, supportive daily trainer from Brooks, you may be trying to decide between two of their most popular options – the Adrenaline GTS 23 and the Glycerin 21.

Both deliver the signature Brooks fit and feel, but there are some key differences when it comes to stability, cushioning, and weight. Read on for a detailed comparison to help you choose the best Brooks trainer for your needs.

Similarities And Differences Between Brooks Adrenaline GTS 23 And Glycerin 21:

FeatureAdrenaline GTS 23Glycerin 21
Launched In20232024
StabilityModerateSupportive
FlexibilityModerateModerately flexible
SizingMen’s 7-15, 17 / Women’s 5-12Men’s 7-13, 14, 15, 17 / Women’s 5-12
WeightMen’s 10.6 oz / Women’s 9.2 oz9.30-10.50 oz
CushioningModerate DNA Loft v2 foamPlush DNA Loft
OutsoleSegmented rubberDurable rubber
MidsoleDNA Loft v2 foamDNA Loft
UpperEngineered 3D Fit Print meshEngineered mesh
Retail Price$140$160

Features Comparison:

Materials:

The Adrenaline GTS 23 uses an engineered 3D Fit Print mesh upper that provides a flexible, breathable fit to keep feet cool and dry even during long runs. The upper material is designed to adapt to the foot’s shape for a contoured, personalized feel.

In the midsole, Brooks utilizes their DNA Loft v2 foam which offers an optimal blend of soft cushioning and energetic responsiveness for a smooth, stable ride.

This proprietary midsole foam provides the right amount of compression without losing resiliency and durability over time. For the outsole, a segmented rubber design helps facilitate flexibility in key areas while also delivering traction and high abrasion resistance for lasting wear.

Brooks Adrenaline GTS 23
ADRENALINE GTS 23

GLYCERIN 21
GLYCERIN 21

The Glycerin 21 features an engineered mesh upper made of tightly knit fabrics for targeted breathability and support. The foot is able to move naturally within the upper without it feeling restrictive.

In the midsole, DNA Loft foam delivers plush, marshmallow-soft cushioning from heel to toe to keep feet protected from impact. This proprietary foam has an optimal blend of softness and responsiveness for all-day comfort.

On the outsole, durable rubber covers high-wear areas for traction and extended durability mile after mile. The outsole rubber also works to stabilize the foot during the gait cycle.

Durability:

The Adrenaline GTS 23’s durable outsole rubber and DNA Loft v2 midsole foam give it excellent durability for a high-mileage trainer. The sturdy rubber in the outsole shows minimal signs of wear even after 150+ miles of use based on initial wear-testers.

The full-length DNA Loft v2 midsole also maintains its cushioning and bounce over prolonged use, with no noticeable packing out or flattening. Many runners report getting well over 300-400 miles in the Adrenaline before any real decrease in cushioning or outsole tread life. This makes the shoe a great value for runners who want a long-lasting workhorse trainer.

The Glycerin 21 is also known for its high level of durability thanks to the sturdy outsole rubber and DNA Loft cushioning in the midsole. The durable rubber outsole has a thickness of 6mm which allows it to handle hundreds of miles of road running with minimal wear and tear.

The full-length DNA Loft foam is also designed to resist packing out or losing its plush step-in feel over time. Most runners can expect to get between 300-500 miles in the Glycerin 21 before signs of midsole breakdown or outsole abrasion. The laces may be less durable than the rest of the shoe based on some user reviews noting fraying.

Fit:

The Adrenaline GTS 23 fits true to size for most runners. The engineered 3D Fit Print upper provides a flexible, accommodating fit. It runs true for both narrow and wide-footed runners.

Brooks Adrenaline GTS 23 Top View
ADRENALINE GTS 23 TOP VIEW

GLYCERIN 21 TOP VIEW
GLYCERIN 21 TOP VIEW

The Glycerin 21 runs true to size but has a more generous, spacious fit compared to the GTS 23. It can comfortably accommodate wider feet but some narrow-footed runners find it too roomy unless sizing down.

Stability:

With its GuideRails support system, the Adrenaline GTS 23 provides moderate stability for overpronators. It is not as stable as a motion-control shoe but gives a good balance of cushioning and support.

The Glycerin 21 offers a stable platform without being overly controlling. It is not specifically designed for overpronators but provides support through its full-length DNA Loft midsole.

Cushioning:

The Adrenaline GTS 23 offers a medium level of cushioning with its DNA Loft v2 foam. It has soft cushioning underfoot but with some responsiveness for a lively ride. It is more cushioned compared to previous versions.

The Glycerin 21 provides an ultra-plush, marshmallow-like ride. Its DNA Loft foam delivers cloud-like softness for maximum shock absorption. It offers the most cushioning in the Brooks lineup.

Value for Money:

The Adrenaline GTS 23 is very competitively priced at $140. The durable materials allow runners to rack up high mileage. Most can expect 300-400 miles before replacing them, making it a great value stability trainer.

The Glycerin 21 justifies its $160 price tag with its plush DNA Loft cushioning and durable rubber outsole. However, the substantial cushioning may feel unstable at faster paces. It excels for easy mileage days and delivers comfort for many miles.

Performance Comparision:

Walking:

The Adrenaline GTS 23 performs well for walking thanks to its cushioned yet responsive midsole. The GuideRails system provides support on longer walks while the roomy forefoot allows natural toe splay.

With its DNA Loft cushioning, the Glycerin 21 offers incredible shock absorption on walks. The plush midsole keeps feet comfortable mile after mile. Some may find it slightly less responsive.

Running:

For medium to high-mileage running, the Adrenaline GTS 23 provides a good balance of responsiveness and cushioning. It has enough cushion for longer distances while still being nimble enough for tempo runs.

The Glycerin 21 excels at slow to moderate-paced running where runners can appreciate its soft, lush cushioning. The shoe provides great shock absorption for high mileage. It is less ideal for fast running.

Plantar Fasciitis:

The Adrenaline GTS 23 adequately supports runners with plantar fasciitis thanks to its stability features and supportive sole unit. However, runners with severe pain may benefit more from a shoe with additional arch support.

With its well-cushioned midsole, the Glycerin 21 helps absorb shock and impact for runners with plantar fasciitis. However, its wide fit may not properly cradle and support sore arches.

Standing All Day:

The Adrenaline GTS 23’s comfortable upper and responsive cushioning make it a good option for standing all day. Features like the GuideRails help fight fatigue in the feet, knees, and hips.

The Glycerin 21 is excellent for standing and walking for prolonged periods. Its plush DNA Loft midsole softens impact and keeps feet comfortable even after hours of wear.

Final Verdict:

For runners needing light stability, the Adrenaline GTS 23 is the better choice between the two. It offers a supportive ride without excessive control or weight. However, for neutral runners seeking maximum cushioning, the Glycerin 21 delivers an ultra-plush soft ride.


Both are durable, comfortable trainers. Choose the Adrenaline GTS 23 if you prefer a livelier, more responsive feel, or size down in the Glycerin 21 for a truly cloud-like run experience. Ultimately, choosing between these two quality shoes comes down to your specific fit and performance preferences.

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