ASICS GEL Four Five One Performance Review

Though I’d prefer to spell out FOUR FIVE ONE for the duration of this review as it accentuates the style factor, 451 is a more concise approach. Still, I mention this at the outset of this article as the bold lettering along the rear of the upper was one of my first observations of the 451 after removing it from the box. The 451 is an Asics racing flat, the first flat I’ve reviewed since the New Balance Hanzo S last May. According to Running Warehouse, the 451 is the new name for the beloved (and discontinued) Hyper Speed series. While the 451 retains many properties of the Hyper Speed, one major revision is likely going to be a tipping point for how it fares in the marketplace.

The Good

Like the Hanzo S, the 451 is light (6.8 ounces in a men’s nine—the Hanzo S is 6.5) and firm, ideal for race day. The shoe retains the full-length SpEVA midsole found in the Hyper Speed, a “blend of EVA and rubber ball material.” The result, according to Asics, improves rebound by 20%. At faster paces, my cadence was high in the 451, and while the shoe is firmer than most, there’s a slight softness that noticeably smooths out the ride. The outsole, comprised of AHAR (Asics High Abrasion Rubber) in the heel and DuraSponge (blown rubber) in the forefoot, delivers reliable traction without slapping.

On to that major change I referenced earlier. Unlike the Hyper Speed series, the 451 swaps shoelaces for the BOA closure system. The concept, unsurprisingly, is straightforward. Slip the shoe on, adjust the tongue, press the dial down, and rotate the knob to the desired tightness. The 451 is indeed a racing flat, but I see no reason why it can’t cross over into triathlons. The low weight, simple upper, and BOA laces provide that distinction when seconds count during transitions.

The Bad

Keep in mind that my remarks about the BOA system skew more towards observation than criticism. Overall, I like the concept, but unlike traditional shoelaces, the BOA pattern inhibits one’s ability to fine tune the fit of the midfoot in a specific spot. This is easier with laces. In his review of the New Balance 1500 T2, Thomas spoke with BOA reps at the 2018 Running Event in Austin, Texas, who believe that this closure system should be in every shoe. Though the 451 is my first BOA shoe, I haven’t arrived at that conclusion yet. To those of you who actively run with shoes that incorporate BOA, what’s your perspective on midfoot fit? Is it as simple as a turn of the dial, or are there any spots that seem loose or susceptible to pain based on where the tightness is felt?

After my second run in the 451, I noticed a small blister on my right heel (the first run produced some minor irritation). Never one to shy away from deciphering how I can lower the risk of hot spots or blisters for subsequent workouts, I changed socks for the third run and applied Run Guard to the affected area. A blister. Again. I’d like to note at this point that I intentionally wore thin socks in the first three runs as the length is close. There’s clearly a delicate dance on sizing for racing flats. They are meant to be snug and secure from forefoot to heel, but the toes still need a reasonable amount of room so the nails stay intact.

For the fourth run, I donned the Balega Hidden Contour, the thickest sock I own. I applied Run Guard again, along with a bandage for added protection. Thankfully, no blister emerged. I’d like to believe that socks factored into this outcome as they are the only variable I changed in the equation, but the increase in thickness consequently made the toes feel slightly more cramped. Which brings me back to sizing. Personally, I’d stick with your true size for 5K and 10K races, but the half-marathon and marathon distance may necessitate a half size increase based on swelling. Food for thought, you know?

ASICS GEL Four Five One Conclusion

I have mixed feelings about the 451. The low weight, breathable upper, and firm ride make it ideal for fast runs and races; however, I’m still on the fence about the BOA closure system and that pesky blister that kept surfacing on my right heel. I haven’t raced in a while, so I may pull the 451 out to see how it fares at serious speed. The price, $114.95, makes it worth a look too.