Anti-Aging: Fatigue Resistance Research



By Coach John Hughes


Several weeks ago I wrote about Anti-Aging: Mastering Fatigue. The bottom line is your perceived exertion of how hard you are working controls how far / fast you can ride, not the physiological workload of your body. Matt Fitzgerald in How Badly Do You Want It uses multiple case studies to illustrate this point. In that column I drew on the book and added my own suggestions of how you can change your perceived exertion.Several studies looked at other factors about why we fatigue.  Good news! Some of these causes are within your control as you age.


Stage Racing

study published in August 2021 looked at Power Profiling and Race Performance of professional and U23 racers during the five-day Tour of the Alps. U23 riders were under 23 and competed in the developmental Continental tier of cycling competition. Nine U23 and eight professional cyclists participated in the study. The researchers looked at power and heart rate data from the five-day Tour of the Alps. They concluded the best predictor of race performance wasn’t raw power or heart-rate. It was fatigue resistance.


 The researchers collected power data during two editions of the stage race.  Then they constructed power profiles for each cyclist and compared the profiles to race performances. To construct the profiles the researchers searched through each rider’s data for the entire five-day race to find the five-second window with the highest average power. They did the same analysis for ten seconds, 15 seconds, and so on up to 30 minutes.


There were no significant differences in the power profiles of the pro and U23 racers up to 30 minutes of racing except the U23s had a higher five-second power than the pros! There also weren’t major differences when they compared power profiles of different types of cyclists like climbers and all-rounders.


But races are longer than 30 minutes.


Researchers then constructed a separate profile of peak power for five seconds, ten seconds and so on for each rider after 40 minutes, 1:00, 1:20, 1:40 and 2:00 hours of racing.


The power profiles of each pro and U23 rider declined from 40 minutes to two hours. The U23 riders’ curves declined more than the pros. (No surprise.) However, the power curves of the individual pros stayed bunched together, indicating very similar performance. The individual U23 power curves were more spread out. The pros had better fatigue resistance.


Quantifying fatigue by declining power output per unit of time is a gross measure. A rider might cruise at a steady 250 watts for an hour.  Or the rider could ride for an hour at 230 watts with a couple of one-minute surges at 600 watts. Although the average power for the hour is the same the latter is more fatiguing. Pro stage races aren’t steady state: intensities range from low to high. Coaches use normalized power rather than average power to measure total workload for a ride. Normalized power takes into account the difference between a steady workout and a fluctuating workout.


The study only involved a small number of cyclists all of whom were elite. The data were collected during a race and an individual’s power curves reflect a team’s tactics and the rider’s job.


Nike’s Breaking2 Project

In 2017 Nike launched a project to have a runner break the two-hour barrier in the marathon. Nike tested at least 16 of its sponsored elite runners to pick a team of three who potentially could run a sub-two-hour marathon. (Nike didn’t reveal the exact number and identities of the tested runners.) Eliud Kipchoge won the eventual race in 2:00:25


Physiologists and coaches have a mathematical model to forecast a runner’s performance in a marathon. The model has three variables to predict a runner performance: 1) VO2 max, 2) running economy, and 3) what fraction of VO2 max a runner can sustain over the course of a marathon. Lactate threshold is often a proxy for the third variable.


Nike published the data on each the runners. In this group of elite runners none of these three variables were extraordinary. After studying the data researchers suggested a fourth variable is also critical, which they called fatigue resistance, representing “the extent of the deterioration of the three [other variables] over time.” 


Improving fatigue resistance

Fatigue results from many factors including the metabolism in your muscles, how much glycogen you still have, changing signals in your nervous system between your muscles and your brain, deteriorating economy of effort, dwindling motivation, etc. The interplay of these factors is different in each athlete.


1. Carbohydrates. Running low on glycogen seems to make fatigue resistance worse. Your muscles burn glucose for energy. The glucose is stored as glycogen until needed.  The glycogen comes from carbs. Data from the Breaking2 project showed that consuming 60 grams of carbohydrates per hour improved fatigue resistance. 60 grams of carbs per hours is what the American College of Sports Medicine recommends. Even if you don’t bonk – run out of carbs completely – your muscles don’t perform as well when you start to deplete your glycogen.  I’ve written two related columns:

3. Economy. A study in the  British Journal of Sports Medicine suggested economy of effort is a key to performance. Your muscle fibers don’t naturally all fire at the same time so some of each pedal stroke is wasted effort, i.e., lower economy. You can improve your economy — the firing pattern of your muscle fibers — by sprinting. You don’t have to your buddies to a stop sign. In your longer rides include two or three 30- to 60-second sprints spaced far enough apart you recover fully.  You could sprint every five minutes, every couple of hours, etc. and get the same benefits.  This is analogous to dialing in the timing of your car’s engine. I wrote this column on how to improve your economy:

4. Motivation. Motivation during a ride keeps you turning the cranks even though you’re getting very tired. The column on Mastering Fatigue explained how to maintain your motivation by changing your perceived exertion of your fatigue.  Consistency of exercise is critical for older riders.  As we age, we lose fitness faster if we don’t exercise regularly.  This column explains:

5. Boredom. We don’t feel as fatigued if we’re riding with others talking and having a good time. However, if we’re bored, we feel the fatigue sooner.  I’ve written two columns on:

You can improve your fatigue resistance by working on each of the five factors.

Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris.


He has written nearly 40 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John’s full bio.  


My eBook Anti-Aging: 12 Ways You Can Slow the Aging Process includes chapters on how to meet the American College of Sports Medicine’s recommendations on aerobic, high intensity aerobic, strength training, weight-bearing exercises, balance and flexibility. I include sample weeks and months for different types and amounts of exercise. I give you plans to build up to 100 km and 100 mile rides. I include a plan to increase over two years your annual riding from around 4,000 miles (6,500 km) to over 5,000 miles (8,000 km) per year. You can easily modify the plans for different annual amounts of riding. I discuss the importance of recovery and how to gauge if you are getting enough recovery. I combine the different kinds of training into programs that balance training and recovery. The 106-page eBook is available here Anti-Aging: 12 Ways You Can Slow the Aging Process