  Within the last decade, running has become one of the most popular physical
activities in the world. Although the benefits of running are numerous, there
is a risk of Running Related Injuries (RRI) of the lower extremities.
Electromyography (EMG) techniques have previously been used to study causes of
RRIs, but the complexity of this technology limits its use to a laboratory
setting. As running is primarily an outdoors activity, this lack of technology
acts as a barrier to the study of RRIs in natural environments. This study
presents a minimally invasive wearable muscle sensing device consisting of
jogging leggings with embroidered surface EMG (sEMG) electrodes capable of
recording muscle activity data of the quadriceps group. To test the use of the
device, a proof of concept study consisting of $N=2$ runners performing a set
of $5km$ running trials is presented in which the effect of running surfaces on
muscle fatigue, a potential cause of RRIs, is evaluated. Results show that
muscle fatigue can be analysed from the sEMG data obtained through the wearable
device, and that running on soft surfaces (such as sand) may increase the
likelihood of suffering from RRIs.
