If you reach that point where you believe you've done everything right—your diet is optimized, training program seems perfect, you feel superfit—but for inexplicable reasons your sports performance isn't improving the way you expected, it's time to visit a data doctor. In recent years, a bumper crop of legitimate performance-testing laboratories have popped up to service ambitious recreational athletes. These types of facilities used to be geared exclusively toward elite pros heading to events like the Tour de France or the Ironman World Championships in Hawaii and are equipped to analyze such biomechanical factors as your lactate threshold (to determine the highest intensity your muscles can sustain), your VO2 max (to measure the aerobic load your muscles can handle at maximum effort), and your pedal cadence and running gait (to identify flaws that can hamper your power and efficiency). Reacting to your unique combination of results, trainers will then prescribe workouts to get you to the top of your game. Note that testing programs will vary between facilities (most offer individual tests and package deals) and you may need follow-up visits to confirm that your new exercise program is on target.

> Cadence Cycling and Multisport Centers, Philadelphia; $125– $225; 215-508-4300, cadencecycling.com

> National Training Center, Clermont, Florida; $75–$175; 352-241-7144, usantc.com

> Boulder Center for Sports Medicine, Boulder, Colorado; $50–$200; 303-544-5700, bch.org/sportsmedicine

> Endurance Performance Training Centers, Mill Valley, California; three-part tests for runners and cyclists, $250; 415-380-9629, enduranceptc.com