Groos was born and raised in Nashville, Tennessee, where she graduated from Harpeth Hall School in 1977. As a ninth grader, she set the national record for the 880 yard run (2:10.06). As a senior, she set a state record in the 1600 meters (4:45.44) that wasn't broken for 40 years. Overall, she won state championships in the 880 yard and the mile run three times, each, while being part of a state champion mile relay and twice being part of Harpeth Hall's state championship team (and being part of their runner-up team another year).
Groos competed in the marathon at the 1988 Summer Olympics in Seoul, Korea, and was an alternate for the 1984 Olympic Games. She twice won the Pittsburgh Marathon, including in 1988, when she ran her personal best (2:29:50).
Groos is married to Paul Sloan. They have two children. Their daughter, Emma, won the Tennessee state cross country championship in 2014 (18:36.25); earlier in high school, she'd finished 4th, 3rd, and then 2nd in the state championships.
- All results regarding marathon, unless stated otherwise
|Representing United States|
|1988||Pittsburgh Marathon||Pittsburgh, United States||1st||2:29:50|
|Olympic Games||Seoul, South Korea||39th||2:40:59|
|1989||Pittsburgh Marathon||Pittsburgh, United States||1st||2:32:39|
On February 20, 1981, at Blacksburg VA Groos set a world indoor record for 5000 meters. Her time was 15:34.5.
- "Tenn.'s Rebecca Story breaks 40-year-old state record in 1,600-meter run". 16 June 2017.
- "A special fan cheers on a special record by Rebecca Story - the Knoxville Focus".
- "Groos, Margaret « Tennessee Sports Hall of Fame".
- "Well Worth a Wait".
- "Ensworth's Sloan finally wins cross country title". The Tennessean.