Emily Matijevich

50 free online copies: tandfonline.com/eprint/BZGNPWW… @UCalgary @uofcknes @ScienceFootwear @sportsbiomechj

Summarized poetically

TAKE AWAY #2: To further improve Advanced Footwear, should we delay the transition from footwear energy storage to return? We speculate the timing of foot + footwear energy return (~40% stance) may be earlier than optimal – given that positive ankle work begins at ~60% stance.

MORE SIMPLY: Runners who received greater magnitudes of energy return from the shoe (or more optimally timed energy return?) had a greater reduction in ankle demand. Would these have also been the athletes that achieved the greatest metabolic energy savings when running in AFT?

TAKE AWAY #1: A post hoc qualitative analysis revealed an exciting trend - runners who had the greatest relative increase in positive foot + footwear work in the Advanced Shoe compared to a Traditional Shoe, also had the greatest decrease in positive ankle work.

FINDING #3: The approximate timing of footwear energy return (estimated as the transition of negative to positive foot + footwear power) varied only slightly across footwear conditions.

FINDING #2: Positive ankle work was ⬇️ in the Advanced Shoe (consistent with prior research), with no significant changes at the knee and hip. Current Advanced Footwear designs primarily modulate the mechanical demand on muscles spanning the ankle joint.

🚨NEW PUBLICATION ALERT🚨 “Greater Foot and Footwear Mechanical Work Associated with Less Ankle Joint Work During Running” tandfonline.com/doi/full/10.10… cc @EricHonert @BennoNigg

FINDING #1: Both negative and positive foot + footwear work were ⬆️ in the Advanced Shoe. However, this was not a linear transitional of the relative mechanical benefit of the shoe observed during benchtop testing – and there was significant variability across runners!

THE HOW: 15 male runners ran overground in three footwear conditions – one Advanced Shoe and two Traditional Shoes. “Foot + footwear” and lower limb joint powers were compared.

STUDY PURPOSE: To evaluate the MAGNITUDE and TIMING of foot, footwear and lower limb joint powers and work while running in “Advanced” and “Traditional” running shoes.

“Foot + footwear” power is a specific application of unified deformable segment analyses methodology. "Foot + footwear" power quantifies the combined energetics of all the rigid and deformable foot and footwear structures.

Fortunately, existing methodologies can support! Unified deformable segment analyses can be harnessed to quantify the net power of complex and non-rigid devices (i.e., prostheses, shoes, body soft tissues, etc.) during locomotion.

This lack of mechanistic understanding may be due to limitations of benchtop energy return material testing – the controlled loading does not replicate the magnitude and timing of shoe material loading and rebound (i.e., mechanical power/work) during actual under foot running.

Despite the large volume of running biomechanics research focused on Advance Footwear Tech (compliant, resilient, and longitudinally stiff running shoes), there is a lack of mechanistic understanding of HOW footwear energy return facilitates changes in running performance.

THE WHY: Sporting equipment often leverages energy storage & return to help athletes run faster, jump higher, and move better. While E return is intuitively good for “propelling athletes”, the magnitude/timing of E return influences the products capacity to enhance performance.

I am hiring PhD students in the Movement Bioengineering Lab at the University of Utah. Please share or apply by January 1! Join us at the intersection of movement biomechanics, computer vision, machine learning, and wearables as we create tools that improve human mobility.

(Implication #2 cont.) "This may give users a false sense of energy (calorie) expenditure. This may be an important area of consideration for consumer physical activity monitor developers.” ⌚ 🤔

Implication #2: “Many physical activity monitors likely consider HR to calculate energy expenditure… during yoga/exercise performed in hot environment, when HR is artificially higher because of the added circulatory demands, energy expenditure may also be artificially inflated"

Implication #1: “Participants may be inclined to reduce their effort during hot yoga, intentionally or unintentionally, as they perceive it to be harder than it actually is, resulting in reduced exercise intensity and consequently minimizing potential fitness adaptions” 🤯

Finding #3: However, identical yoga sessions performed in a thermo-neutral and hot environment result in similar energy expenditure because of similar rates of oxygen consumption VO2 (hot = 30.9% ± 2.3% vs. thermo-neutral = 30.5% ± 1.8%, p = 0.68)