John Schaeffer (born March 14, 1951) is a renowned American sports and fitness trainer, author and nutritionist, best known as the athletic trainer of Apolo Ohno. He specializes in sports conditioning (physical exercise), nutrition and weight management. A five time World Powerlifting and Superheavyweight Kickboxing Champion, Schaeffer owns and operates the Winning Factor Sports Sciences division in Shillington, Pennsylvania, one of the top gymnasiums in the United States, a training and nutrition facility for amateur and professional athletes. He frequently travels as a seminar professor to certify personal trainers for the International Sports Sciences Association.
According to Apolo Ohno, "I was looking for someone to take me to the next level." Schaeffer is a Ph.D. candidate in nutrition and was awarded the Order of Ikkos Medallion at the 2010 Vancouver Olympic Games for his outstanding training work with Apolo Ohno, winner of eight Olympic medals, the most decorated American Winter Olympic Games athlete of all time (two Olympic Gold Medals, two Olympic Silver Medals, and four Olympic Bronze Medals) and a champion on television's Dancing With The Stars, dancing Pasodoble, hip-hop and freestyle dance with break-dancing, scoring a perfect 30 in the final. According to Schaeffer, "Every nutrient we consume has a purpose. If it doesn't have a purpose, we (the athletes) don't consume it. Strength and power are two different things. You can be extremely strong, but not convert it to power. When they bleed, you bleed. When they cry, you cry. When they rejoice, you rejoice. When they win (the athletes) you win, and it's an amazing place you're taking (them). It's indescribable. You almost have to experience it to understand."  In 2010 and 2011, Schaeffer trained U.S. cruiserweight champion Carl Davis (boxer), and in 2011 and 2012 trained former NABA and NABF light middleweight champion Angel Hernandez (boxer).
Noted athletes trained by John Schaeffer
- Allison Baver, Short track women's Olympic speed skating champion
- Gabriel 'Tito' Bracero, unbeaten NABF light welterweight champion currently ranked # 34 in the world by the World Boxing Council
- Kermit Cintron, World Boxing Organization Welterweight champion
- Carl Davis (boxer), former USBO Cruiserweight champion from Chicago.
- Shani Davis, Long track men's Olympic speed skating champion
- Esteban Gonzalez, 3 time Puerto Rican Golden Gloves finalist at 135 pounds
- Mark Fretta, the top ranked Triathlete in the world
- Angel Hernandez (boxer), former NABA and NABF Light middleweight champion
- Wayne Johnsen, super middleweight boxer, semi-finalist on television's The Contender
- Giddeon Massie, National Sprint (cycling) champion
- Julio Cesar Matthews, world ranked unbeaten cruiserweight contender.
- Jameel McCline, World Boxing Organization North American Boxing Organization and World Boxing Council Continental Americas heavyweight champion
- LeSean McCoy, Philadelphia Eagles Running Back
- Ray Mercer, World Boxing Organization Heavyweight champion
- Apolo Ohno, Short track men's Olympic speed skating champion, winner of 8 Winter Olympic Games medals, winner of Dancing With the Stars competition, best-selling author of the book 'Zero Regrets' (several chapters devoted to John Schaeffer)
- Samuel Pagan, three time New York State Golden Gloves champion at 130 pounds
- Mikhail Starov, world International Powerlifting Federation Powerlifting champion
- Stevenson Sylvester, 'Sly', Pittsburgh Steelers Linebacker
- Alexander Zolkin, World Boxing Council and World Boxing Organization Heavyweight champion
- Robert Johnson, Tennessee Titans
Noted recording artists physically conditioned by John Schaeffer
- Shiloh (singer), Canadian pop singer
- Said Abboud Massari, Lebanese Canadian pop, R&B, and hip hop singer
Apolo Ohno and John Schaeffer interviews
- Apolo Ohno on his trainer John
- John Schaeffer in the gym on WCAU TV-10 NBC Philadelphia, explaining his unique program of diet and exercise, and Apolo Ohno 
- "Apolo Ohno Sheds 16 pounds But Wins Eight Medals". People Magazine interview with John Schaeffer on His Training Work with Apolo Ohno.
Fitness books by John Schaeffer
- "John Schaeffer". Readingeagle.com. Retrieved 2011-01-12.
- "ISSA Founders, Advisors, and Course Authors". Issaonline.com. Retrieved 2011-01-12.
- "ISSA Congratulates Seminar Professor John Schaeffer - CARPINTERIA, Calif., Feb. 24 /PRNewswire/". California: Prnewswire.com. 2010-02-23. Retrieved 2011-01-12.
- Karin Mallett (2010-03-02). "Olympic Trainer Returns From Vancouver - News Story - WFMZ Allentown". Wfmz.com. Retrieved 2011-01-12.
- "Top Olympic honors go to Cumru Township man". Readingeagle.com. 2010-03-15. Retrieved 2011-01-12.
- Wang, Cynthia (2010-02-27). "Apolo Ohno Sheds 16 Lbs. But Wins Eight Medals - Page 20746986 - Winter Olympics 2010, Apolo Anton Ohno". People.com. Retrieved 2011-01-12.
- "Reading's Trainer to the "Stars"". NBC Philadelphia. 2010-03-15. Retrieved 2011-01-12.
- "Carl Davis Wins USBO Cruiserweight Title | Boxing News". Saddoboxing.com. 2010-12-18. Retrieved 2011-01-12.
- Wang, Cynthia (2010-02-27). "Apolo Ohno Sheds 16 Lbs. But Wins Eight Medals - Winter Olympics 2010, Apolo Anton Ohno". People.com. Retrieved 2011-01-12.
- "The Winning Factor (9780871318459): John Schaeffer: Books". Amazon.com. Retrieved 2011-01-12.
- "The Winning Factor for Women (9780871318718): John Schaeffer: Books". Amazon.com. Retrieved 2011-01-12.