Sciatica – lower back pain caused by an irritation or compression of the sciatic nerve at the top of the buttocks

Second Wind – returning breathe and energy, generally after 15-20 minutes intense working out

Shin Splints – microscopic tears in the muscles attached to the shin bones, often due to improper running form, can be prevented/treated with stretching or shin muscle exercise, can cause stress fractures 

Singlet – a sleeveless shirt often favored by runners for its light weight and breathability
Skinfold Calipers – an instrument used to grip folds of skin to measure “Body Composition”

Slow Twitch – muscle fibers that contract slower than “Fast Twitch” fibers but are more efficient and effective using energy on longer distance runs 

Speed Work – quick intervals of sprinting alternated with slower-paced “Recovery Runs” 

Split Time – the difference in the amount of time a runner takes to complete a certain distance within a longer race compared to an equal distance in the same race; for example, a runner in a two mile race might run the first mile in seven minutes and the second mile in five for a one minute split time

Stability – a running shoe’s structural integrity and ability to guide the foot’s form and resist unwanted movement during the run

Stamina – the power to continue running

Strength Training – workouts designed to build muscle, usually refers to weight lifting

Stretching – extending the muscles to their maximum length in an effort to increase flexibility and reduce injury and soreness 

Stride – the length of each step; while a lengthy stride can increase running speed, an elongated stride in which the leading leg extends to nearly straight, can lead to injuries

Supination -- a running form lacking the natural inward roll of the foot (See “Pronation”), can lead to injuries and muscle strain, can be corrected by flexible, properly cushioned shoes; also called “Under Pronation”

Supplex -- a patented nylon fabric manufactured by DuPont, known for its soft cotton feel, moisture absorption and quick drying abilities