I have to admit, when I first saw the TRX Suspension Trainer, I was a bit skeptical. “It looks like just a bunch of straps,” I thought. “How will this improve my runners’ performances?”
Part of my skepticism came from being trained as a scientist. Neither physiological concepts related to endurance performance nor scientific research support strength training as a way to improve distance running performance. Distance running performance is limited by the cardiovascular system’s ability to deliver oxygen to the working muscles. It is also limited by the ability of the muscular and metabolic systems to extract the oxygen from the blood and use it to regenerate energy for muscle contraction. Given the anaerobic nature of resistance training, one would not expect it to improve these aerobic abilities.
Furthermore, no research has shown that strength training improves VO2max (the maximum volume of oxygen your muscles consume per minute) or lactate threshold (the fastest sustainable aerobic speed above which lactate accumulates and acidosis occurs), two important physiological variables that reflect the abilities of the cardiovascular and muscle metabolic systems that determine distance running performance. However, some research has shown that when muscular strength or power is achieved through improving the neural aspects of muscle contraction (which requires lifting very heavy weights for only a few reps per set or by training with explosive plyometrics), running economy (the amount of oxygen used to maintain specific submaximum speeds) is improved.
So where does all of that leave room for training with the TRX for oxygen-consuming distance runners? I’ve used it as part of my athletes’ supplemental, non-running training as a second workout of the day. While supplemental exercises such as resistance and flexibility training may not have a direct impact on distance running performance, they can improve the athlete’s overall fitness, increase muscular strength and reduce the chance of injury. I like to think of supplemental training as exercises and activities that prepare the runner for more formal training and to handle greater training loads. In other words, supplemental training trains runners to train.
What I have found is that the most beneficial aspects of the TRX are its versatility and functionality. You can literally use it anywhere and train many different movements. While I have yet to determine whether or not training with the TRX makes my athletes run faster for a 10K or marathon, it does seem to improve their core strength and functional movement, aspects of fitness they can’t get from their running training alone.
Dr. Jason Karp is a nationally recognized speaker, writer and exercise physiologist who coaches runners of all levels through RunCoachJason.com. He holds a PhD in exercise physiology and is founder and coach of REVO2LT Running Team. He writes for international running, coaching and fitness magazines and scientific journals and is the author of "How to Survive Your PhD" and "101 Developmental Concepts and Workouts for Cross Country Runners."