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/100 by , posted on .

I've been known to acquire a pair of running shoes with a specific race in mind, as with Helios SR.

TP100 is a 100-mile foot race along the river Thames in England, from the Richmond suburb of London to Oxford, with a cut-off time of 30 hours.

Helios SR is La Sportiva's lightest, most minimal offering. The flat, mostly dirt track and often paved nature of the route made this an ideal match between the task at hand and the tool. As things turned out, I wasn't far off the mark but the shoes fell short of being a masterpiece that they could have been.


Typical terrain on the Thames Path

La Sportiva Helios SR Specifications

Out of the box, the shoes surprised with their lightness (480 grams per pair of Men's US 9) and their flexibility. The plushness of upper and forefoot height of 23mm belied their low drop of 2mm. They looked and felt comfortable, just sitting in my hands.


La Sportiva Helios SR- The Looks 


Initial shorter runs with the shoes were promising too. True to specs, the shoes were light, flexible, well-cushioned, and comfortable, with a slipper-like fit.

Much like Bushido, the other La Sportiva shoe I had experience with, the shoes sized small and I needed to go up a full size from the usual for other brands. (For reference, I am UK10 in Salomon, Adidas, and New Balance, and 9.5 in Brooks and Asics. The Helios SR I needed was 10.5.) 

Flexibility & The Wave Sole

One feature which provides the shoes with the lightness and flexibility is the "wave" sole, with 9 crests. The dips consist of an exposed midsole and in my view the biggest "sole" reason for the shoe's downfall – I'll explain.


Midsole is composed of responsive injected EVA


According to La Sportiva, the injected midsole (as opposed to standard compression molded EVA) provide for a higher degree of cushioning and better elasticity. I can attest to the fact that the feel is definitely more "springiness" than "mushiness," and that to me is a good thing, particularly on the drier, harder surfaces.

I can attest to the fact that the feel is definitely more "springiness" than "mushiness," and that to me is a good thing, particularly on the drier, harder surfaces.


The wave sole


I did my longest run, 30 miles, along with an earlier section of the race route a month out from the race, and came away with no doubt that these will be the shoes I'll use on race day.

The shoes felt comfortable, and aside from the usual discomfort that comes from a long run and many hours out, no obvious alarm bells. Such was my confidence that I opted not to pack a back-up for either the 50-mile or 80-mile drop bags.

Comfort & the Upper

A big contributor to the comfort is the gusseted tongue, which works somewhat like the Endo-sock feature in some of the higher-end Salomons and serves to provide a wrap-around fit as well as keeping debris out.


The Gusseted Tongue

The Rockplate or Lack Thereof

The one immediate point I did notice about the shoe, however, was the lack of a rock-plate or similar forefoot protection, as would have pretty much been the norm in off-road shoes, particularly since La Sportiva markets these as their "sky running" model. 

This was ostensibly to allow for maximum flexibility and lightness but nevertheless was surprising given the mountain running heritage of La Sportiva, which is based in the Italian Dolomites region.

As things were, every once in a while, even on well-groomed dirt track and grass that I was predominantly running on, I'd trod on a small stone right on the groove where the only thing separating my foot from the object was mere millimeters of midsole material and sockliner, and the sharp resulting pain was certainly noticeable. 

I made a mental note to not take these out on technical trails where there was a high likelihood of debris and sharp rocks.


Frixion XT dual-compound outsole

Durability & the Outsole 

The other point to note is the use of sticky rubber compound in the outsole.

La Sportiva actually has 4 different rubber compounds ranging from very "sticky" as in grippy (and non-durable) to very durable (and non-sticky) and combinations of the compounds are used in various parts of the outsole to maximize traction and durability. 

What it amounts to is that the Helios SR employs a dual compound outsole where the black section in the fore- and mid-foot is the sticky rubber (explaining the SR part of the name) and a harder wearing yellow compound is used on the heel.

It's a great idea but, ultimately I was left wondering the point of it all since the lack of a rock-plate meant I was unlikely to be using the shoes on highly technical terrain where the grippy sole compound would really have come into their own.

As things stood, the sticky rubber just meant a quicker wearing outsole with no tangible benefits for the type of terrain that in my view the shoes were best suited for.


Nice Italian design touch


In summary, I liked the Helios SR for their lightness and flexibility which was conducive for "natural" running while at the same time providing decent cushion and responsiveness.

The shoes are very comfortable, breathe well, and the 4mm Ortholite sockliner adds to the plushness. They were well-suited for the non-technical, dry trails that I used them on, and served me well on the 100-miler along the Thames River. 

I won't hesitate to reach for them next time I do a long run on a well-groomed single track. The lack of a rock-plate, however, is to me a major oversight for a trail shoe, particularly if it is being marketed as sticky-soled and for mountain running, and one should seriously be considered for the updated version, even if it comes at a slight cost to weight and flexibility.

As for the upper, nothing needs to be changed there. As things stand, the shoe is a near-masterpiece, which is a great shame.

| Level 4 expert Verified
I am a runner. Running shoes are my tools of trade, and I take my tools seriously. I believe in the right tool for the right job and find joy in both the search for, and when matters come together to result in an enjoyable outing. Trail, road, 5k to 100 milers and everything in between- I've done them all!

Updates to La Sportiva Helios SR

  • La Sportiva brings to the fore an ultra-aggressive and strikingly lightweight trail shoe that can tackle technical terrains, rocky areas, steep inclines, or downhill bombs with aplomb in the Helios SR. As the SR stands for Sticky Rubber, La Sportiva uses a new compound in the Frixion XT to deliver all-around traction that most trail runners would dearly love to have in their trail shoes. For comparison, the Merrell Trail Glove 5 has similar functionality. The shoe has enough stickiness that it can very well be a rock climbing footwear, instead of just a trail version.
  • The fully gusseted and stretchable upper keeps debris off while it continues to make breathability such a huge feature in this shoe. Because it adapts quite well to the runner’s foot, the upper accommodates different foot dimensions and eases off the constrictive feeling from a company that normally produces shoes that tends towards being narrow.
  • The signature part of the Helios SR is the wave pattern in the outsole, which adds more flexibility to the shoe and helps keep the weight of the shoe down despite the excellent cushioning and underfoot protection coming from a lightweight package.

Size and fit

The fit runs on the narrow side like most La Sportiva shoes. As mentioned, the decent stretch coming from the upper helps the Helios SR accommodate runners with slightly wider feet. It also eases off the constrictive feel if worn right out of the box. The volume and width of the toe box are just about enough for the runner to be comfortable. Available widths are the standard D for the men’s and B for the women’s. Sizing is a bit off since it is half a size smaller than regular measurement. Again, most of La Sportiva’s shoes are built this way. Sizes are from 6 to 15 for the men’s and 5 to 11 for the women’s.


The outsole of the La Sportiva Helios SR is identified by the wave pattern. This is designed to add maximum flexibility as befitting of a lightweight shoe with minimalist tendencies. The lugs in the outsole are super aggressive and are covered by a new rubber compound in the Frixion XT that substantially increase its traction on a multitude of trail surfaces, even in wet conditions.


La Sportiva uses a full-length Morpho Dynamic EVA for consistent cushioning and shock dispersal. An Endurance Platform EVA Insert works in the midfoot to provide torsional rigidity and a little arch support. While the shoe is without a rock protection plate, it relies on a flexible, compressed EVA in the forefoot to protect the foot from sharp objects on the trail.


The upper is largely made of the Hydrain Nylon Mesh for impressive durability and breathability. It has decent stretch to really mold itself to the runner’s foot. La Sportiva strategically placed the synthetic overlays to provide excellent support and structure without adding weight to the shoe. An Ortholite Sockliner with anti-microbial and moisture wicking features adds to the wraparound feel and step-in comfort. The tongue is well-padded, fully gusseted, and stays in place all through the run. A TPU material that covers the eyelets to the midfoot help deliver a snug fit without being overbearing.


The current trend of La Sportiva Helios SR.
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Jens Jakob Andersen
Jens Jakob Andersen

Jens Jakob is a fan of short distances with a 5K PR at 15:58 minutes. Based on 35 million race results, he's among the fastest 0.2% runners. Jens Jakob previously owned a running store, when he was also a competitive runner. His work is regularly featured in The New York Times, Washington Post, BBC and the likes as well as peer-reviewed journals. Finally, he has been a guest on +30 podcasts on running.