Considerations in the Triathlon Suit Design Process

Considerations in the Triathlon Suit Design Process
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07th March 2023

The tri-suit is unique in the world of sport. In the design and testing stage of a tri-suit, consideration is given to the challenges triathletes face when competing in three disciplines (swimming, cycling and running).

  • The same tri-suit is worn though out an event and is required to be optimised for the 3 different disciplines (S/B/R).
  • A tri-suit has to perform in 2 types of media - water (swimming) and air (cycling and running) and differing velocity of travel in each of the disciplines.
  • Consideration should be given to the distances the tri-suit will be worn for (sprint/Olympic/ironman) in each of the three disciplines.

The tri-suit design influences the physiological comfort needs of wellbeing and performance for an athlete.


The tri-suit needs to be a tight fit to the body, but not so tight to restrict the movement of arms and legs in any of the three disciplines. A tri-suit needs to fit like a second skin to reduce DRAG. Any loose clothing, rippled, or torn will increase drag through the water when swimming or cycling/running in air.

Swimming:- Features possibly used in tri-suits for reducing the drag in the water

  • Fabrics which provide a tight fit/cling to the body – reducing the wetted area.
  • Fabrics that compress the muscles and mould the shape of the body.
  • Improve the laminar flow by reducing turbulent flow around the tri-suit.
  • Fabrics with vortex generators to reduce flow separation by using protuberances on the tri-suit.
  • Hydrophobic fabric which means very little water is absorbed by the fibers which make up the fabric.
  • Sewn, bonded, welded seams that follow the direction of the water flow.

Cycling:- Wind drag on a flat road can be 70%- 90% of the total resistance a rider may experience while pedaling. The drag force increases with the square of the wind speed. Drag is always present and is dependent on different parameters (i.e., speed of travel, helmet design, positioning on the bike, clothing worn, bike aerodynamics). Features used in tri-suits for reducing the drag in air

  • Fabrics which provide a tight fit/cling to the body to decrease the flow separation.
  • Fabrics with vortex generators to reduce flow separation by using protuberances on the tri-suit.
  • The design of the tri-suit and fabric type chosen, positioning to gain maximum drag reduction.
    • Seam positioning
    • Coatings applied to materials
    • Coverage – shoulders, upper arms, down to knee (as required by ITU rules).

Running:- Due to the relative slow speed attained while doing the run discipline (compared to cycling speeds) the drag force is much lower. Introducing any drag force reducing features so that any triathlete could gain an advantage is impossible. Triathletes come in all shapes and sizes.

This leads onto another consideration in tri-suit design which is more related to cycling and running – Thermoregulatory evaluation. What is thermoregulatory? How does it affect a triathlete?


Thermoregulation is a process that allows your body to maintain its core internal temperature. All thermoregulation mechanisms are designed to return your body to homeostasis. This is a state of equilibrium. A healthy internal body temperature falls within a narrow window. The average person has a baseline temperature between 98°F (37°C) and 100°F (37.8°C). Your body has some flexibility with temperature. However, if you get to the extremes of body temperature, it can affect your body’s ability to function if your body temperature falls to 95°F (35°C) or lower, you have “hypothermia.”  If your body temperature rises as high as 107.6°F (42 °C), you can suffer brain damage or even death.

Tri_Suit Design v Thermoregulation

Helping a triathlete control his internal body temperature is an important aspect of designing a tri-suit for comfort. Ignoring the thermo requirements, can influence wellbeing, efficiency, and performance. The mechanical, thermal and moisture interactions of the body with the tri-suit, influence the athlete’s thermoregulatory responses within varied range of environmental climates and physical activities.

A study conducted by Olga Troynikov, Elnaz Ashyer in “Thermoregulatory evaluation of triathlon suits in regards to their physiological comfort properties” [2] stated

 “This study demonstrated that the physiological comfort properties of triathlon suits are determined by both the fabrics and materials used and also the design and construction of the garments. It is possible by altering the design of the garment and, most importantly, by selection of the materials with relevant performance attributes, to engineer the garments with optimal performance.”

The study [2] mentions several factors which can affect the performance of a tri-suit on a triathlete.

  • Fabric - thickness and density of the fabric.
  • Total garment weight.
  • Fabric with open mock-mesh construction allowed the mesh openings in the surface of the fabric to be open to the environment and thus to effectively transfer heat generated by the body of an athlete to the environment.
  • Fabric thickness has a critical impact on the thermal insulation of the suits.

Tenola tri suits are available to buy here >


1.) Joseph C. Mollendorf, Albert C. Termin Ii , Eric Oppenheim , And David R. Pendergast, in Effect of Swim Suit Design on Passive Drag, 2004

2.) Olga Troynikov* , Elnaz Ashyeri in Thermoregulatory evaluation of triathlon suits in regards to their physiological comfort properties.



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