Isn’t Strength Training just for Weight-Lifting and Strength/Power-Based Athletes?
Nope! I have written a lot on strength training in previous posts of mine, but a recent study has me excited as it is one of the first studies to take a look at how a long-term strength training program impacts exercise economy specifically in triathletes. There have been numerous studies done showing that exercise economy is improved in cyclists and runners that undertake a regular, heavy-load strength-training program (1); however, this research has largely been done in single-sport athletes. Son, in theory, the effects of strength training on exercise economy in triathletes is not precisely known as this research has not been done.
It is no surprise that triathlon is different from its’ single-sport counterparts that undertake stand-alone swimming, cycling, and running. One of the biggest differences is that each discipline of triathlon has a cumulative fatiguing effect on the subsequent discipline, reducing exercise economy in the process. For example, runners participating in a stand-alone marathon undertake this endeavor fresh, whereas in triathlon, an Ironman-distance triathlete would undertake the marathon portion of the event carrying significant fatigue from the swim and bike, and these previous two disciplines have a negative impact on running economy compared to a marathon that was done when fresh and not preceded by a swim and bike.
Strength training, however, is known to improve exercise economy, particularly in cycling and running (1). Exercise economy is typically defined as the energetic cost (oxygen consumption) associated with a sustained power or pace output (2). Exercise economy is thought to be improved through strength training by the following mechanisms:
Improved ability to store and release elastic energy from increased musculotendinous stiffness. This primarily impacts running which is a sport that requires the utilization of storing and releasing elastic energy with every stride
Improved rate of force development (RFD) of musculature. This is primarily a neural improvement of the musculature’s ability to generate force quickly
Increased maximal strength. This allows for a greater recruitment of less fatigable, type 1 slow-twitch muscle fibers during submaximal cycling and running
These improvements described above ultimately improve exercise economy, which means a reduction in the oxygen demand during submaximal exercise, thereby improving performance. Exercise economy has been well-established as a valid marker or predictor of endurance performance, with a greater exercise economy predicting better endurance performance (1,2).
However, no research has been done to date examining strength training’s impact on triathletes during successive swimming, cycling, and running. Luckin-Baldwin and colleagues (2) attempted to change this by conducting the first study of its kind in which strength training and its impact on exercise economy was examined in triathletes during a simulated long-distance triathlon. Let’s take a look at this study and the findings.
Strength Training for Triathletes
This study took 25 well-trained, long-distance triathletes and randomly assigned them to 26 weeks of concurrent strength training and endurance training (n=14) or just endurance training (n=11). The concurrent strength/endurance group performed 26 weeks of progressive strength training in addition to their usual endurance training, whereas the endurance only group simply performed their usual endurance training. The strength training program consisted of two sessions per week, with weeks 0-12 consisting of moderate loads (8-12 repetitions @ <75% of one rep maximum) and weeks 14-26 consisting of heavy loads (1-6 repetitions @ >85% one rep maximum). There was a two-week break in the middle of the strength training program to allow recovery. All study participants completed a simulated triathlon consisting of a 1500-meter swim, a 60-minute cycle, and a 20-minute run at weeks 0, 14, and 26 while researchers collected exercise economy data and other measures.
The concurrent strength/endurance group saw improvements in maximum strength over the entire 26 weeks as well as improvements in cycling economy at week 14 and running economy at week 26 with no changes in total body mass. The endurance-only group did not see any improvements in cycling nor running economy at any time points.
These findings are about what we would expect given the published literature documenting the beneficial effects of strength training on cyclists and runners, but this is the first study of its kind to demonstrate these improvements in triathletes. Interestingly, cycling economy improved after only 12 weeks of moderate-load strength training while running economy only improved after the heavy-load strength training phase at week 26. Typically, very heavy loads and/or explosive strength training elicit improvements in exercise economy, but there has been some research showing that moderate loads can improve exercise economy during cycling, and this might explain why these improvements in exercise economy were only seen in cycling at week 14 whereas running economy didn’t improve until week 26 (2).
Another important finding was that these improvements in maximum strength and exercise economy occurred without an increase in body weight. This is important as some endurance athletes worry that engaging in strength training will lead to an increase in muscle mass, and therefore an increase in total body mass, and lead to a reduction in endurance performance. However, this is typically not the case as it is pretty well-documented that concurrent endurance and strength exercise prioritizes endurance adaptation over muscle hypertrophy adaptations. Endurance exercise is known to inhibit intracellular signaling pathways important for muscle protein synthesis and growth, which likely explains why concurrent endurance and strength training typically does not yield significant increases in muscle size, particularly in endurance athletes that engage in large amounts of endurance training (2).
You might be wondering why swimming economy was not improved? Well, first of all, it was not measured, but strength training is also not known to typically improve swimming economy even though strength training for swimmers is still recommended.
Finally, this study did not measure objective performance outcomes, so it was not possible to extrapolate the improvements in exercise economy to any improvements in objective performance during the simulated triathlon. However, exercise economy is such a strong predictor of endurance performance, that it is very likely that improvements in exercise economy would translate to some form of measurable objective performance during a triathlon (1). However, further work will of course be needed to demonstrate this.
While the general findings of this study are not groundbreaking in and of themselves, these findings are the first of their kind in triathletes specifically. It is exciting to see that a concurrent strength/endurance program can positively impact cycling and running economy while improving maximum strength in triathletes without an increase in body mass. The findings add further justification for the recommendation for triathletes to engage in long-term strength training, not only for general injury prevention, but for improved exercise economy.
Bazyler CD, Abbott HA, Bellon CR, Taber CB, Stone MH. Strength training for endurance athletes: theory to practice. Strength & Conditioning Journal. 2015 Apr 1;37(2):1-2.
Luckin-Baldwin KM, Badenhorst CE, Cripps AJ, Landers GJ, Merrells RJ, Bulsara MK, Hoyne GF. Strength Training Improves Exercise Economy in Triathletes During a Simulated Triathlon. International Journal of Sports Physiology and Performance. 2021 Feb 11;16(5):663-73.
Happy training and racing!
-Ryan Eckert, MS, CSCS
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