Even though you sleep more, drink coffee and take vitamins, fatigue returns, especially at the end of the day. This observation also speaks to runners: during a marathon, many feel drained well before the line. Researchers have wondered why some hold on, while others collapse even though they have, on paper, the same level.
To explain it, they describe a new measure, called the
fatigue resistance : the ability to maintain the same efficiency despite the accumulated effort. It helps to understand why you sometimes end a meeting, a run or a day of work completely drained. The good news is that this resistance is growing, and science points to a very specific lever.
Resistance to fatigue: the fourth dimension of your energy
For a long time, physiologists have evaluated endurance with three numbers: VO2 max, lactate threshold and running economy, that is to say the amount of energy expended for a given pace. This vision assumed that these values remained stable. Recent work shows that they deteriorate with exercise, and much more quickly in some than in others.
In a study conducted at Loughborough University, 28 trained runners ran for 90 minutes at a steady pace while their running economy was measured every 15 minutes. Above all
bodybuildingtheir energy cost increased by 4.7% over the session. After a targeted program, the drift was only 2.1%. In other words, they kept the same stride longer for less fuel.
Why strength training changes the way you fatigue
This program included two weekly sessions ofstrength training with heavy loads (back squat, one-sided press, calf presses) and explosive plyometric exercises, repeated for ten weeks. Compared to the control group, these runners also saw their time until exhaustion at 95% of their VO2 max increase by around 35%, when the group without strength training fell by 8%. Their usable tank has increased, a sign of fatigue resistance increased.
Other studies where adults performed 45 minutes of strength training every two to four days for ten weeks led to the same findings: after 90 minutes of effort, the running economy drops less, and high intensity can be tolerated for longer. At the cellular level, experiments published in a scientific journal show that trained muscle becomes more efficient in using available energy.
Apply science to your daily fatigue, even without being sporty
In elderly people suffering from sarcopenia, three weekly sessions of gentle strengthening for twelve weeks increased strength, muscle thickness, reduced the feeling of fatigue and improved quality of life.
Research summaries associate approximately one hour of strengthening per week with a 40 to 70% reduction in cardiovascular risk and a more active metabolism.
For an adult exhausted from work, simple sessions of 30 to 40 minutes, twice a week, focused on the legs, glutes and core, are already enough to make stairs, shopping or playing with children much less exhausting.