ASICS Novablast 5 Review: Features, Specs & Ironman Ban

You’ve probably heard a running buddy rave about the Novablast. The fifth version arrived with a lighter build and softer foam, and it quickly became one of the most talked-about shoes of early 2025. But then Ironman banned it, which left a lot of runners wondering: is this the best daily trainer money can buy, or a shoe you can’t actually race in? Here’s what the data and testers actually say.

Weight (men’s size 9): 9.3 oz (264 g) ·
Heel-to-toe drop: 8 mm ·
Stack height (heel/forefoot): 40 mm / 32 mm ·
Price: $150 (USD) ·
Category: Neutral daily trainer ·
Midsole foam: FF BLAST PLUS ECO

Six key specs, one pattern: the Novablast 5 packs maximalist cushioning into a package that’s lighter and more flexible than its predecessor.

What Are Asics Novablast 5 Good For?

What type of runner is it best for?

• The Novablast 5 is built as a neutral daily trainer for road running. Its standout feature is the FF BLAST PLUS ECO foam, which ASICS reports delivers an 8.5% increase in bounce properties compared to earlier versions (The Runner Beans (running shoe review outlet)).
• This makes it a strong fit for runners who want one shoe that handles easy recovery jogs, steady long runs, and moderate tempo efforts without needing to switch pairs.
• Runners who pronate heavily should look elsewhere—the Novablast 5 lacks any medial post or guidance frame typically found in stability models.

What are its key features?

• The midsole uses FF BLAST PLUS ECO, a sustainable foam blend that retains high energy return while reducing weight compared to prior Novablast versions (The Runner Beans (running shoe review outlet)).
• Lab testing by RunRepeat (independent shoe testing lab) found the shoe requires 11.2N of force to flex 30 degrees in a bend test, compared to 17.8N for the Novablast 4—a 37% improvement in flexibility.
• The outsole features a pod-like groove in the forefoot that ASICS says is designed to propel runners forward during toe-off (The Runner Beans (running shoe review outlet)).

The implication: this shoe delivers versatility without compromise for its target audience, but overpronators must look elsewhere.

Is the Novablast 5 Good for Running Fast?

Can it handle speed work and intervals?

• The FF BLAST PLUS ECO foam is noticeably bouncier than prior Novablast iterations, which gives it a responsive feel when you pick up the pace (The Runner Beans (running shoe review outlet)).
• RunRepeat’s bend-test data shows the shoe is 37% more flexible than the Novablast 4 (RunRepeat (independent shoe testing lab)), which helps with turnover during tempo runs and strides.
• Several testers have noted that the shoe feels a touch too soft for all-out sprinting or track-repeats where a stiffer, more aggressive platform helps (The Runner Beans (running shoe review outlet)).

How does it compare to a traditional speed shoe?

• The bouncy foam provides a responsive feel at faster paces, but it lacks the carbon plate or stiff rocker geometry found in true racing flats and super-shoes.
• The Run Testers (four-runner review crew) noted the shoe’s versatility for daily training and marathon pacing, calling it a solid middle ground between a plush cruiser and a racer.
• For interval sessions at 5K pace or faster, a lighter shoe with a plate will still be the better pick—but for marathon-paced tempos, the Novablast 5 holds its own.

The pattern: the Novablast 5 is fast enough for the vast majority of runners’ speed needs, but elite-level sprinters and sub-3-hour marathoners will want a dedicated speed shoe.

Can I Run a Marathon in the Novablast 5?

Is it suitable for race day?

• Yes—many runners have used it for full marathons. The cushioning remains comfortable over 26.2 miles, and the foam doesn’t go flat even in the later stages (The Runner Beans (running shoe review outlet)).
• RunDNA (running analysis and review site) called it “the OG fun daily trainer is back,” highlighting the playful ride that makes the miles feel easier.
• However, there’s a critical catch: the shoe is banned from Ironman events and Ironman 70.3 races due to stack height regulations (The Runner Beans (running shoe review outlet)).

What do marathon runners say about it?

• Firm responses from Facebook groups and the Run Testers confirm marathon suitability—testers report the shoe feels good even after mile 20.
• The 8mm drop and 40mm heel stack provide enough protection for road marathons without feeling clunky or unstable.
• Runners targeting a Boston or New York City Marathon will find plenty of cushion for the distance—just don’t plan on wearing it to Kona.

Why Is Novablast 5 So Popular?

What makes it stand out from other daily trainers?

• The shoe is lighter, softer, and bouncier than the Novablast 4, while maintaining the same $150 price point (RunRepeat (independent shoe testing lab)).
• The FF BLAST PLUS ECO foam is a sustainable material that retains energy return, appealing to runners who care about the environmental impact of their gear (The Runner Beans (running shoe review outlet)).
• Versatility is the key: the shoe handles everything from recovery runs to marathon pace, reducing the need for a quiver of specialized trainers.

How does it improve on the Novablast 4?

• RunRepeat’s lab (independent shoe testing lab) data shows the Novablast 5 is lighter and more flexible than its predecessor, with a 37% improvement in bend-test compliance.
• The midsole is softer than the Novablast 4, which gives it a plusher feel underfoot (The Runner Beans (running shoe review outlet)).
• However, testers at The Runner Beans note that the softer foam has slightly reduced snap or energy return compared to the Novablast 4—a trade-off between plushness and pop.

The trade-off: you get a plusher, lighter shoe, but you lose some of the lively snap that made the Novablast 4 a cult favorite among runners who liked a firmer platform for faster days.

Why Did Ironman Ban the Novablast?

What are the Ironman shoe regulations?

• Ironman’s World Triathlon Corporation (WTC) enforces a maximum allowable stack height of 40 mm for shoes used in all Ironman and Ironman 70.3 events starting in 2025.
• The Novablast 5 has a heel stack height that exceeds 40 mm when measured including the insole and outsole, according to The Runner Beans (running shoe review outlet) (which reported 41.5 mm for the heel).
• RunRepeat’s measurements (independent shoe testing lab) show the forefoot stack at 33.5 mm, confirming the shoe sits above the 40 mm threshold specifically at the heel.

Will the ban affect other races?

• USAT (USA Triathlon) and the ITU (International Triathlon Union) have not yet adopted the same 40 mm stack height limit, so the Novablast 5 remains legal in those events for now.
• ASICS has not released a modified version of the Novablast 5 that complies with Ironman’s regulation.
• It’s unclear whether other race organizations will follow Ironman’s lead, leaving triathletes in a waiting pattern.

The pattern: a regulation designed for elite fairness creates an unexpected trap for age-group triathletes buying what they think is a versatile trainer.

Confirmed Facts vs. What’s Unclear

What Runners and Reviewers Say

“The Novablast 5 is lighter, softer, and bouncier than the Novablast 4.”

— RunRepeat testers (cut-in-half review)

“The shoe’s versatility for daily training and marathon pacing makes it a standout in the crowded daily trainer category.”

— The Run Testers (four-runner review crew)

“The OG fun daily trainer is back.”

— RunDNA (running analysis and review site)

Three different reviewers, three different angles, but one consistent thread: the Novablast 5 brings joy back to everyday running, even if it’s not the most aggressive speed shoe on the market.

For a detailed breakdown of how the Novablast 5 compares to its predecessor, check out this ASICS Novablast 5 review.

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