3 Day Ultra

Case Study

Introduction

In September 2017 Malc Kent traveled to Golden, BC to perform a 3 day outdoor gait analysis on veteran marathoner and ultra runner Martin Parnell. Martin’s stated objective was to complete the challenging 85km 3 stage course within the time limits and without injury. The nature of the event and the environment provided a unique opportunity for Malc to test the latest wearable technology solutions in terms of battery life, reliability and durability.

Method

Martin was kitted out with the following sensors from his wrists to his feet: Garmin 310XT watch, Garmin 735XT watch, Garmin chest heart rate monitor, LumoRun sensor, dorsaVi ViMove sensors, Stryd power meter and RunScribe footpods. All the sensors were tested during training runs at west Bragg Creek in the 2 weeks leading up to the race and all sensors were checked for calibration immediately before the start of stage 1 of the event. At the finish line of each stage Malc stopped the recording, retrieved the sensors, downloaded the data and recharged the batteries.

The data plots presented below represent simplified summaries of the entire dataset collected in order to emphasize the critical trends. Overall across the 3 days 22 different parameters were measured by 7 sensor sets.

Day 1: 5km mountain ascent

Day 1 was a 5km long climb up Kicking Horse Mountain with a total elevation gain of 1000m on a mix of dirt trail, grass and gravel (elevation profile in green).

Terms: Left leg and right leg (L and R), ground reaction force (GRF), initial peak acceleration (IPA), ground contact time (GCT), absolute symmetry index (ASI). Load rate and power are also presented in N/min and W respectively. For more see definitions section below.

Day 2: 60km mountain trail run

Day 2 was an extended loop incorporating a major mountain summit ascent and descent on a mix of dirt trail, grass and gravel (elevation profile in green).

Terms: Left leg and right leg (L and R), ground reaction force (GRF), initial peak acceleration (IPA), ground contact time (GCT), absolute symmetry index (ASI). Load rate and power are also presented in N/min and W respectively. For more see definitions section below.

Day 3: 20km trail run

Day 3 was a hilly out and back trail course on a mix of dirt trail and asphalt pathway (elevation profile in green).

Terms: Left leg and right leg (L and R), ground reaction force (GRF), initial peak acceleration (IPA), ground contact time (GCT), absolute symmetry index (ASI). Load rate and power are also presented in N/min and W respectively. For more see definitions section below.

Definitions:

GRF>> the force or load returned from the ground back into the body.

IPA>> the peak acceleration or impact felt by the body at footstrike.

GCT>> the length of time the foot is on the ground.

ASI>> the percentage asymmetry between the left and right values.

Load Rate/Power>> the speed at which the force is applied and returned to the body.

3

DAYS

17

HOURS

85

KM

92311

FOOTSTRIKES

Discussion

Firstly it is worth commenting on the durability and reliability of the technology used. All of the watches and sensors were intact and fully functioning at the end of the event. A testament to their smart design and secure fitting. Some of the sensors such as the LumoRun struggled to keep recording each day and registered large data gaps of several hours. The most reliable and long lasting sensors were the dorsaVi ViMove and the RunScribe footpods. Both lasted to the finish line of each day and recorded huge quantities of data. The RunScribe pods in particular had extremely few data gaps (less than 20min across the 3 days).

 

controlled effort throughout

 

Overall Martin’s data reflects a brilliant execution of controlled effort throughout. On day 1 his dataset shows that he was still maintaining consistent power output at the top of the climb and that his left-right symmetry was very good throughout. Even his cadence was well maintained no matter the incline, terrain and fatigue. On day 2 Martin’s data shows very high levels of control with symmetrical values throughout and consistent cadence, impact and power output no matter whether ascending or descending mountainous terrain. On day 3 the fatigue was clearly a major factor after so much challenging running and Martin’s symmetry began to change to more asymmetric values. However the data still highlights a very controlled approach that ultimately was enough to get him safely to the event finish line. With Martin’s asymmetry metric becoming more and more pronounced at the end of day 3 it is probably a good thing that this was his last day running.

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Published on malckent.run  25 March 2018

Malc Kent M.Sc, MSci, B.Sc, CSCS

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