Including strength training in endurance (running, triathlon) training programs is something I’ve been doing for a while now.
I had initially included it mainly based on sport performance research, but also because I saw the performance benefits in athletes I worked with.
There are typically 2 areas of strength training endurance athletes should be focused on, and they are both critical for performance:
Type 1: strength/power.
Type 2: muscular endurance.
This new study from the University of Oklahoma studied the impact of 8 weeks of High Volume Resistance Training (Type 2) on trained cyclists.
Specifically, they were looking at how quickly lactate builds up in the muscles (commonly incorrectly referred to as lactic acid) in trained cyclists after 8 weeks of Type 2 training.
The result: athletes who trained 2x per week for 8 weeks saw a significant delay in the onset of lactate. In other words, their muscles were able to function hard for a longer period of time before the accumulation of lactate caused them to fatigue.
What is Type 2 training? In the programs I design for athletes, I called it Work Capacity: a high volume of work, with high repetitions, minimal to no rest, low weight, for a long-ish duration (30-45min).
In the study mentioned above, they had athletes do a high number of reps using gym machines (leg press, leg curl, leg extension).
Bottom line: this study demonstrates that Type 2 training delays onset of muscle fatigue in endurance athletes. So if you are such an athlete, make sure to incorporate such training in your regimen.